Transform coding scheme for a digital time-varying signal

Abstract

Decoder, encoder and method for decoding and encoding are presented. The decoder for block-wise decoding a digital time-varying signal from a data stream is configured to perform decoding of a transform of a current block from a data stream. The decoder is configured to perform the decoding of the transform by: predicting and obtaining a last-position pointer for a current block, and / or decoding an offset value decoded from the data stream, and / or selecting a binarization scheme out of a set of predefined binarization schemes, and / or decoding and determining a number of greater-than bins for each significant transform coefficient, and / or context-adaptively entropy decoding coefficients of the transform from the data stream by selecting a context set, and / or context-adaptively entropy decoding a significance flag for coefficients of the transform and syntax elements for significant coefficients and selecting a context for context-adaptively entropy decoding a currently decoded significance flag of a current coefficient.

Description

[0001] Transform Coding Scheme for a Digital Time-Varying Signal

[0002] Description

[0003] Technical Field

[0004] Embodiments according to the invention are related to apparatuses and methods for encoding or decoding a digital temporally-varying signal such as a channel of a multi-channel digital signal.

[0005] Technical Background

[0006] In biomedical waveform coding, where signals are acquired from sensors attached to the human body, data can be either stored in its raw form or compressed using simple methods such as Differential Pulse Code Modulation (DPCM). While such basic methods offer ease of implementation, applying a more advanced compression scheme can significantly reduce the required bit rate, especially when allowing for slight distortions that do not compromise the integrity or utility of the signal in its final application.

[0007] Given that biomedical signals are typically multi-channel and one-dimensional, audio compression techniques may initially appear suitable. However, they often fall short in terms of compression efficiency when compared to dedicated compression technologies, such as hybrid coding schemes. In hybrid compression, the signal is divided into chunks (referred to as blocks). Each block undergoes a series of sequential processing steps: prediction, transform, and quantization, with optional filtering applied before, during, or after these stages. The resulting quantization indices and auxiliary parameters are then encoded into a bitstream using entropy coding.

[0008] This hybrid approach is conceptually similar to architectures used in video compression. However, biomedical waveforms exhibit distinct characteristics, especially in their statistical behavior, which directly impacts the entropy coding stage. Therefore, compression techniques must be carefully adapted to these unique properties, setting biomedical waveform coding apart from conventional audio and video compression methods.

[0009] The ITU-T initiated the development of a dedicated compression technology for biomedical waveforms, recognizing the growing demand for efficient storage and transmission of FH250306PEP-2026098855. DOCX filing version PCT, rmphysiological data. The technology currently under development adopts a hybrid compression architecture, delivering significantly higher compression efficiency than conventional audio compression methods.

[0010] At its core, the architecture utilizes Context-Based Adaptive Binary Arithmetic Coding (CABAC) for entropy coding, which enables an efficient representation of encoded data. It also supports a range of prediction and transform modes, along with a flexible configuration of onedimensional block sizes, tailored to the characteristics of biomedical signals. To maximize compression performance, the encoder is designed to evaluate the available coding tools dynamically and choose the most appropriate configuration for the given input signal.

[0011] For a given block, entropy coding using CABAC proceeds as follows:

[0012] 1. Signaling the Last Significant Position:

[0013] The position pLof the last non-zero (significant) value, relative to the first position in the block, is signaled.

[0014] 2. Reverse Scanning:

[0015] Starting from the last significant position pL, the values are encoded in reverse order, moving toward the first position p0in the block.

[0016] 3. Encoding Each Level:

[0017] For each coefficient ctat pp.

[0018] • A significance flag bsigis coded to indicate whether the value is non-zero (c^O).

[0019] • If the value is non-zero:

[0020] o A truncated unary code is used, where each bin signals whether the absolute value exceeds a defined threshold (|c -1 >tj).

[0021] o If the maximum number of bins for the truncated unary code is reached and the value still exceeds the final threshold (I |-1 >t™az), the remaining absolute information (|ci|-1-t™“x) is encoded using a Oth- order Exponential-Golomb code.

[0022] o Finally, the sign bin of the non-zero value is signaled.

[0023] CABAC (Context- Based Adaptive Binary Arithmetic Coding) operates in two modes: adaptive context-based coding and bypass mode. All of the coding steps described above utilize context models, with two exceptions: the suffix of the Exponential-Golomb code and the sign bin, both of which are encoded using the bypass mode.

[0024] FH250306PEP-2026098855. DOCX filing version PCT, rmContext modeling — the process of selecting an appropriate context model for coding each binary value, or bin — is carried out as follows:

[0025] • For significance coding, the absolute levels of the three preceding positions are summed and clipped to a maximum of two. This results in three possible context model offsets ml,„.

[0026] • The computed offset is then applied relative to a context model set, a second offset m- ig, which is determined based on the current position within the block. These offsets are fixed and implemented via a lookup table (LUT). The final context model offset is then msig=m^g+ms2ig.

[0027] • A different context model set may be selected when Trellis-Coded Quantization (TCQ) is used for quantization, allowing for adaptation to the statistics of different quantizers based on the selection within TCQ.

[0028] For the truncated unary code — used to indicate whether an absolute value exceeds a specific threshold — context modeling employs a single fixed context model, while still applying the concept of context model sets, similar to what is done for significance flag coding.

[0029] If the absolute value exceeds the maximum threshold that be represented by the truncated unary code, the remaining part is encoded using a Oth-order Exponential-Golomb code with context models. In this case:

[0030] • A fixed set of context models is defined.

[0031] • Each unary bin in the prefix of the Exponential-Golomb code uses one context model from this set.

[0032] • The context model offset is incremented with each successive bin, but is capped at the last context model in the set. If there are more bins than context models, the final bins share the last context model.

[0033] The suffix of the Oth-order Exponential-Golomb code is encoded using bypass mode. Similarly, the sign information is also encoded in bypass mode.

[0034] The described design was originally developed for a coding architecture that leverages highly efficient prediction and transform modes, along with typical block sizes, resulting in residual signals with statistical properties which are close to those observed in video compression. However, the domain of biomedical waveform coding is broader and more diverse. In certain application scenarios, prediction may not be feasible, or much larger block sizes may be necessary to capture relevant signal characteristics. Under such conditions, the statistical

[0035] FH250306PEP-2026098855. DOCX filing version PCT, rmbehavior of the residual signal deviates significantly from the coding conditions which the coding itself was optimized for.

[0036] To address this, this invention introduces a level coding scheme specifically designed to accommodate the unique statistical properties of various biomedical signal types. This approach enhances compression efficiency across a wide range of coding scenarios where conventional methods perform suboptimal. By adapting the coding strategy to the actual distribution and structure of biomedical data, the proposed method achieves more robust compression suitable for diverse biomedical applications.

[0037] It is an objection of the present invention to provide improved concepts for codecs supporting biomedical waveform coding, the concepts being improved in terms of coding efficiency, such as compression rate and / or reduced bitrate overhead.

[0038] This is achieved by the subject matter of the independent claims of the present application.

[0039] Further embodiments according to the invention are defined by the subject matter of the dependent claims of the present application.

[0040] Summary of the Invention

[0041] In accordance with a first aspect, a decoder for block-wise decoding a digital time-varying signal from a data stream is provided. The decoder is configured to predict a last-position pointer for a current block of the digital time-varying signal to obtain a last-position predictor. The decoder is configured to decode a last-position residual from the data stream. The decoder is configured to correct the last-position predictor using the last-position residual to obtain a last-position pointer. The decoder is configured to decode first coefficients of a transform in an interval from a first coefficient of the transform to a coefficient of the transform pointed to by the last-position pointer from the data stream and infer that second coefficients of the transform have a predefined value. The decoder is configured to reconstruct the current block using the transform. The decoder is configured to predict the last-position pointer based on one or more last-position pointers of further transforms of previously decoded blocks of the digital timevarying signal

[0042] Therefore, the decoder performs a prediction of the last-position pointer by decoding the lastposition residual from the data stream and correcting the last-position pointer using the decoded last position residual. The prediction of the last-position pointer is carried out utilizing FH250306PEP-2026098855. DOCX filing version PCT, rminformation from previously decoded blocks of the digital time varying signal, such as one or more last-position pointers of further transforms of previously decoded blocks, and thus exploiting the statistical dependencies of the digital time-varying signal (e.g. the biomedical waveform signal), as present in different last-position pointers. By the measure of last-position pointer prediction, the decoder can utilize the information indicated by the last-position pointer, namely relating to a position of a transform coefficient which may be relevant for transform coding purposes, such as a last-significant position, among the transform coefficients and achieve an improved transform coding. This is in particular evident from the decoder decoding the first coefficients of the transform using the interval which runs from the first coefficient until, and including, the coefficient pointed at by the predicted last-position pointer. Thus, the decoder achieves cognizance of the first coefficients, which for example may be a set of coefficients which are significant (or e.g. non-zero), by utilizing its prediction of the last-position pointer, as well as of the second coefficients of the transform, by inferring that they have a predefined value. The decoder reconstructs the current block using the transform, and since the decoder is aware of the significance of the coefficients of the transform, the decoder achieves an improved coding efficiency such as in terms of an increased compression rate and / or a reduced bitrate overhead.

[0043] In accordance with a second aspect, a decoder for block-wise decoding a digital time-varying signal from a data stream is provided. The decoder is configured to decode an offset value for a current block of the digital time-varying signal from the data stream. The decoder is configured to decode a transform of the current block from the data stream. The decoder is configured to reconstruct the current block using the transform in a form offset-compensated using the offset value.

[0044] Therefore, the decoder permits decoding of the offset value (e.g. a bias value, or the offset value being related to the bias value) associated with the current block and uses it to reconstruct the current block using the decoded transform corrected, or adjusted, according to the decoded offset value. By this measure, the decoded transform is compensated for the offset value, and thus being in a form which is offset-compensated used for the reconstruction of the offset block. In this manner, the decoder provides an advantageous implementation of the idea where the offset value, such as being expressed by a large absolute DC coefficient, could be removed and signaled separately, which the decoder then decodes and takes into account after decoding of the transform (e.g. the inverse transform) for the reconstruction of the current block. Thus, the decoder handles the coding of the offset value separately from the coding of the transform, thereby reducing the inefficiencies arising from having to code the offset value together, such as inseparably, with the transform. In other words, inefficiencies in FH250306PEP-2026098855. DOCX filing version PCT, rmtransform coding are avoided, such as by bias removal from a residual signal. In particular, for the scenario where the offset value is specified by a large absolute value, the decoder of the second aspect is equipped to perform block-wise decoding in an improved manner, achieving an improved coding efficiency such as in terms of an increased compression rate and / or a reduced bitrate overhead.

[0045] In accordance with a third aspect, a decoder for block-wise decoding a digital time-varying signal from a data stream is provided. The decoder is configured to decode a transform of a current block of the digital time-varying signal from the data stream. The decoder is configured to reconstruct the current block using the transform. The decoder is configured to decode each of coefficients of the transform by decoding a bin string of one or more bins from the data stream, debinarizing the bin string to obtain a quantization level of the respective coefficient and dequantizing the respective coefficient. The decoder is configured to select a binarization scheme out of a set of predefined binarization schemes for at least one of the coefficients depending on one or more previously decoded coefficients of the transform of the current block and / or a characteristic of one or more previously decoded blocks of the digital time-varying signal.

[0046] Therefore, the decoder of the third aspect provides an adaptive binarization strategy for decoding coefficients of the transform. In this regard, the decoder has at its disposal a set of binarization schemes for at least one coefficient (e.g. one or more coefficients) of the coefficients of the transform. The decoder then permits a selection of a binarization scheme from the set of binarization schemes for the at least one coefficient (e.g. one or more coefficients) of the coefficients of the transform. The selection depends upon the one or more previously decoded coefficients of the transform block and / or a characteristic of the one or more previously decoded blocks of the digital time-varying signal. By this measure, in selecting the binarization scheme, the decoder utilizes, or exploits, the statistical dependencies in the digital time-varying signal, such as the dependencies being present for a characteristic, or property, of previously decoded blocks and / or previously decoded coefficients of the same block as the one being decoded, and thus, performs block-wise decoding in an improved manner, achieving an improved coding efficiency such as in terms of an increased compression rate and / or a reduced bitrate overhead.

[0047] In accordance with a fourth aspect, a decoder for block-wise decoding a digital time-varying signal from a data stream is provided. The decoder is configured to decode a transform of a current block of the digital time-varying signal from the data stream. The decoder is configured to reconstruct the current block using the transform. The decoder is configured to decode each FH250306PEP-2026098855. DOCX filing version PCT, rmof significant coefficients of the transform by decoding a number n of greater-than bins gtj with 0<i<n+1, indicating whether an absolute quantization level of the respective significant coefficient is greater than i, and determine n for at least one of the significant coefficients depending on one or more previously decoded coefficients of the transform of the current block and / or a characteristic of one or more previously decoded blocks of the digital time-varying signal.

[0048] Therefore, the decoder permits an adaptive, or flexible, transform coding strategy wherein, for each significant coefficient, the decoder adaptively decodes the number n of greater-than bins indicative of the magnitude of the quantization level of the respective significant relative to a predetermined threshold, e.g. i. The decoder dynamically determines the number n by utilizing or exploiting statistical dependencies of the digital time-varying signal, such as the determination depending on dependencies being present for a characteristic, or property, of previously decoded coefficients of the transform of the current block and and / or previously decoded coefficients of the same block as the one being decoded. By this measure, the decoder benefits from the dynamic determination of the number n of the greater-than bins associated with the quantization of coefficients of the transform, since the number n could be dependent on coding conditions under which the coefficients of the transform of the blocks of the digital time-varying signal were coded in the data stream. Thus, the decoder overcomes the shortcomings of a fixed number of greater-than-bins and achieves an improved coding efficiency such as in terms of an increased compression rate and / or a reduced bitrate overhead.

[0049] In accordance with a fifth aspect, a decoder for block-wise decoding a digital time-varying signal from a data stream is provided. The decoder is configured to decode a transform of a current block of the digital time-varying signal from the data stream. The decoder is configured to reconstruct the current block using the transform. The decoder is configured to, in decoding the transform from the data stream, context-adaptively entropy decode coefficients of the transform from the data stream by selecting, for a currently decoded coefficient, a context set Csei out of a collection of m context sets Cj with 0<i,sel<m+1 and entropy decoding the currently decoded coefficient using a context selected out of the selected context set Csei, and select the context set Cseiby selecting a set of m thresholds tj,swith to,s=O, tm,s=2s-1 and tj-i,s<ti,sfor all i depending on a size 2sof the current block wherein s is between smin and smax and selecting sei so that a coefficient position j of the currently decoded coefficient falls into an interval [tsei-i,s,tsei,s], wherein the thresholds tj,sare selected so that 1) tj,s-tj-i,smonotonically increases for i for all Smin— s< Smax and 2) there exists at least one Sthres with Smin— Sthres Smax and ithres with 0 < Ithres Hl, SO that tj_above,s_above"ti_above-1,s_above IS CjrOatOr than tj_above-1,s_above "ti_above-2,s_above and FH250306PEP-2026098855. DOCX filing version PCT, rmti_above,s_above"ti_ above, s_above-1 IS greater than tj_above,s_above-1_ti_above,s_above-2 fOT all m + 1 > i abOV6 — i_thres and all smax > s_above > s_thres.

[0050] Therefore, the decoder according to the fifth aspect provides for a more adaptive and scalable context-adaptive entropy decoding approach such as with respect to mapping of positions across different block sizes. This flexible and scalable approach involves a two-fold selection in the course of context-adaptive entropy decoding of the coefficients of the transform: a first selection pertaining to a selected context set Cseiand a second selection involving a context selected out of the selected context set Csei- The selection of the selected context set Cseiis carried out in a manner which pertains to selection of thresholds depending on block size, quantization step size and position of the currently decoded transform coefficients in relation to selected thresholds. Further, the nature of the selection of the selected context set Cseiinvolves selecting thresholds increasing monotonically across context sets, which permit the decoder to have a design of the quantization step size increase across block sizes as well as context sets. Thus, the decoder provides a more flexible and more efficient context-adaptive entropy decoding of transform coefficients, and achieves an improved coding efficiency such as in terms of an increased compression rate and / or a reduced bitrate overhead.

[0051] In accordance with a sixth aspect, a decoder for block-wise decoding a digital time-varying signal from a data stream is provided. The decoder is configured to decode a transform of a current block of the digital time-varying signal from the data stream. The decoder is configured to reconstruct the current block using the transform. The decoder is configured to, in decoding the transform from the data stream, context-adaptively entropy decode a significance flag for coefficients of the transform, and, for coefficients for which the significance flag indicates significance, one or more syntax elements indicative of a quantization level, wherein the decoder is configured to select a context for context-adaptively entropy decoding a currently decoded significance flag of a current coefficient by quantizing a sum of values derived from quantization levels or the significance flag and the one or more syntax elements of previously decoded coefficients within a template placed at a position of the current coefficient.

[0052] Therefore, the decoder according to the sixth aspect decodes the coefficients of the transform by using a context modeling approach with a template, which is more efficient at utilizing or exploiting the statistical dependencies of the digital time-varying signal (e.g. biomedical signals). This approach avoids inefficiencies of known approaches, which may overestimate or incorrectly estimate the probability of large coefficients in sparse signals, and thus improves coding efficiency. The approach involves the decoder performing a selection of the context based on quantization of a sum of values derived from at least one of: quantization values, FH250306PEP-2026098855. DOCX filing version PCT, rmsignificance flags and syntax elements associated with previously decoded coefficients within a template placed at the position of the current coefficient. By this measure, higher absolute levels in previous positions have less weight in the selection of the context model. Thus, the decoder provides a more flexible and more efficient context-adaptive entropy decoding of transform coefficients, and achieves an improved coding efficiency such as in terms of an increased compression rate and / or a reduced bitrate overhead.

[0053] According to a further aspect is provided an encoder configured to encode the data stream decodable by the decoders of the first, second, third, fourth, fifth, and sixth aspect.

[0054] According to a further aspect is provided a method for decoding or encoding as described herein. That is, methods corresponding to decoding or encoding performed by the decoder or the encoder of the first, second, third, fourth, fifth, and sixth aspect are provided.

[0055] According to a further aspect is provided a data stream encoded according to any encoding method (or by any encoder) described herein. That is, data streams corresponding to being encoding by the encoders of the first, second, third, fourth, fifth, and sixth aspect are provided.

[0056] According to a further aspect is provided a computer program product for implementing any method disclosed herein when being executed on a computer or signal processor. That is, computer programs for implementing any method of decoding or encoding corresponding to the decoders or the encoders of the first, second, third, fourth, fifth, and sixth aspect, when being executed on a computer or a signal processor, are provided.

[0057] Brief Description of the Drawings

[0058] The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. In the following description, various embodiments of the invention are described with reference to the following drawings, in which:

[0059] Fig. 1 shows an encoder for encoding a multi-channel digital signal into a data stream as well as decoder for decoding the multi-channel digital signal from the data stream;

[0060] Fig. 2 shows an embodiment of a decoder configured to determine a last-position pointer;

[0061] Fig. 3 shows an embodiment of a decoder configured to perform an offset compensation;

[0062] Fig. 4 shows an embodiment of a decoder configured to use an adaptive binarization;

[0063] FH250306PEP-2026098855. DOCX filing version PCT, rmFig. 5 shows an embodiment of a decoder configured to adaptively select a number of greater-than flags;

[0064] Fig. 6 shows an embodiment of a decoder configured to use position-dependent context model sets;

[0065] Fig. 7 shows exemplarily a context selection for coefficients at different position within current blocks of different sizes;

[0066] Fig. 8 shows exemplarily thresholds for different context model sets for current blocks of different sizes; and

[0067] Fig. 9 shows an embodiment of a decoder configured to use context modeling with template.

[0068] Detailed Description of the Drawings

[0069] The present disclosure proceeds further with some introductory remarks, followed by a short description of the concepts of the present invention before proceeding further with the detailed description of the drawings.

[0070] In the following, a general framework of a coding scheme (e.g., for a decoder and / or an encoder) will be described according to a first, second, third, fourth, fifth and sixth aspect. However, these aspects are freely combinable, e.g., wherein any one or more features of one aspect is freely combinable with any features of any other aspect. Features of these aspects are subsequently described in more detailed examples in sections, “Last Significant Position”, “Bias Removal”, “Adaptive Binarization”, “Number of “Greater Than” Flags”, “Position Dependent Context Model Sets” and “Context Modeling with Template”. A broader framework is subsequently described with reference to Fig. 1. Features described aspects, sections and the framework are freely combinable with any other embodiment disclosed herein.

[0071] In the following, different inventive embodiments and aspects will be described.

[0072] Also, further embodiments will be defined by the enclosed claims.

[0073] For example, the disclosure encompasses the following combinations of the aforementioned aspects:

[0074] FH250306PEP-2026098855. DOCX filing version PCT, rm• each aspect individually (“Last Significant Position”; “Bias Removal”; “Adaptive Binarization”; “Number of “Greater Than” Flags”; “Position Dependent Context Model Sets”; “Context Modeling with Template”),

[0075] • any combination of two aspects (e.g., “Last Significant Position”+”Bias Removal”, “Last Significant Position”+”Adaptive Binarization”, “Last Significant Position”+”Number of “Greater Than” Flags”, “Last Significant Position”+”Position Dependent Context Model Sets”, “Last Significant Position”+“Context Modeling with Template”, “Bias Removal”+”Adaptive Binarization”, “Bias Removal”+”Number of “Greater Than” Flags”, “Bias Removal”+”Position Dependent Context Model Sets”, “Bias Removal”+“Context Modeling with Template”, “Adaptive Binarization”+”Number of “Greater Than” Flags”, “Adaptive Binarization”+”Position Dependent Context Model Sets”, “Adaptive Binarization”+“Context Modeling with Template”, “Number of “Greater Than” Flags”+”Position Dependent Context Model Sets”, “Number of “Greater Than” Flags”+“Context Modeling with Template”, “Position Dependent Context Model Sets”+“Context Modeling with Template”),

[0076] • any combination of three aspects (e.g., “Last Significant Position”+”Bias Removal”+”Adaptive Binarization”, “Last Significant Position”+”Bias Removal”+”Number of “Greater Than” Flags”, “Last Significant Position”+”Bias Removal”+”Position Dependent Context Model Sets”, “Last Significant Position”+”Bias Removal”+“Context Modeling with Template”, “Last Significant Position”+” Adaptive Binarization”+”Number of “Greater Than” Flags”, “Last Significant Position”+”Adaptive Binarization”+”Position Dependent Context Model Sets”, “Last Significant Position”+” Adaptive Binarization”+“Context Modeling with Template”, “Last Significant Position”+”Number of “Greater Than” Flags”+”Position Dependent Context Model Sets”, “Last Significant Position”+”Number of “Greater Than” Flags”+“Context Modeling with Template”, “Last Significant Position”+”Position Dependent Context Model Sets”+“Context Modeling with Template”, “Bias Removal”+” Adaptive Binarization”+”Number of “Greater Than” Flags”, “Bias Removal”+”Adaptive Binarization”+”Position Dependent Context Model Sets”, “Bias Removal”+”Adaptive Binarization”+“Context Modeling with Template”, “Bias Removal”+”Number of “Greater Than” Flags”+”Position Dependent Context Model Sets”, “Bias Removal”+”Number of “Greater Than” Flags”+“Context Modeling with Template”, “Bias Removal”+”Position Dependent Context Model Sets”+“Context Modeling with Template”, “Adaptive Binarization”+”Number of “Greater Than” Flags”+”Position Dependent Context Model Sets”, “Adaptive Binarization”+”Number of “Greater Than” Flags”+“Context Modeling with Template”, “Adaptive Binarization”+”Position Dependent Context Model

[0077] FH250306PEP-2026098855. DOCX filing version PCT, rmSets”+“Context Modeling with Template”, “Number of “Greater Than” Flags”+”Position Dependent Context Model Sets”+“Context Modeling with Template”),

[0078] • any combination of four aspects (e.g., “Last Significant Position”+”Bias Removal”+”Adaptive Binarization”+”Number of “Greater Than” Flags”, “Last Significant Position”+”Bias Removal”+”Adaptive Binarization”+”Position Dependent Context Model Sets”, “Last Significant Position”+”Bias Removal”+”Adaptive Binarization”+“Context Modeling with Template”, “Last Significant Position”+”Bias Removal”+”Number of “Greater Than” Flags”+”Position Dependent Context Model Sets”, “Last Significant Position”+”Bias Removal”+”Number of “Greater Than” Flags”+“Context Modeling with Template”, “Last Significant Position”+”Bias Removal”+”Position Dependent Context Model Sets”+“Context Modeling with Template”, “Last Significant Position”+” Adaptive Binarization”+”Number of “Greater Than” Flags”+”Position Dependent Context Model Sets”, “Last Significant Position”+”Adaptive Binarization”+”Number of “Greater Than” Flags”+“Context Modeling with Template”, “Last Significant Position”+” Adaptive Binarization”+”Position Dependent Context Model Sets”+“Context Modeling with Template”, “Last Significant Position”+”Number of “Greater Than” Flags”+”Position Dependent Context Model Sets”+“Context Modeling with Template”, “Bias Removal”+” Adaptive Binarization”+”Number of “Greater Than” Flags”+”Position Dependent Context Model Sets”, “Bias Removal”+”Adaptive Binarization”+”Number of “Greater Than” Flags”+“Context Modeling with Template”, “Bias Removal”+”Adaptive Binarization”+”Position Dependent Context Model Sets”+“Context Modeling with Template”, “Bias Removal”+”Number of “Greater Than” Flags”+”Position Dependent Context Model Sets”+“Context Modeling with Template”, “Adaptive Binarization”+”Number of “Greater Than” Flags”+”Position Dependent Context Model Sets”+“Context Modeling with Template”),

[0079] • any combination of five aspects (e.g., “Last Significant Position”+”Bias Removal”+”Adaptive Binarization”+”Number of “Greater Than” Flags”+”Position Dependent Context Model Sets”, “Last Significant Position”+”Bias Removal”+”Adaptive Binarization”+”Number of “Greater Than” Flags”+“Context Modeling with Template”, “Last Significant Position”+”Bias Removal”+”Adaptive Binarization”+”Position Dependent Context Model Sets”+“Context Modeling with Template”, “Last Significant Position”+”Bias Removal”+”Number of “Greater Than” Flags”+”Position Dependent Context Model Sets”+“Context Modeling with Template”, “Last Significant Position”+”Adaptive Binarization”+”Number of “Greater Than” Flags”+”Position Dependent Context Model Sets”+“Context Modeling with Template”, “Bias

[0080] FH250306PEP-2026098855. DOCX filing version PCT, rmRemoval”+”Adaptive Binarization”+”Number of “Greater Than” Flags”+”Position Dependent Context Model Sets”+“Context Modeling with Template”), and

[0081] • the combination of all six aspects (e.g. “Last Significant Position”+”Bias Removal”+”Adaptive Binarization”+”Number of “Greater Than” Flags”+”Position Dependent Context Model Sets”+“Context Modeling with Template”).

[0082] It should be noted that any embodiments as defined by the claims can be supplemented by any of the herein described details (features and functionalities).

[0083] Also, the embodiments described can be used individually, and can also be supplemented by any of the features in another section, or by any feature included in the claims.

[0084] Also, it should be noted that individual aspects described herein can be used individually or in combination. Thus, details can be added to each of said individual aspects without adding details to another one of said aspects.

[0085] Moreover, features and functionalities disclosed herein relating to a method can also be used in an apparatus (configured to perform such functionality). Furthermore, any features and functionalities disclosed herein with respect to an apparatus can also be used in a corresponding method. In other words, the methods disclosed herein can be supplemented by any of the features and functionalities described with respect to the apparatuses.

[0086] Moreover, features and functionalities disclosed herein relating to a method, in particular an encoding method can also be used in a data stream or bitstream (e.g. defining a respective data stream or bitstream element). Furthermore, any features and functionalities disclosed herein with respect to an apparatus can also be used in a corresponding data stream, e.g. as a resulting data stream as providing by said encoder. In other words, the data streams disclosed herein can be supplemented by any of the features and functionalities described with respect to the apparatuses and methods.

[0087] Also, any of the features and functionalities described herein can be implemented in hardware or in software, or using a combination of hardware and software, as will be described in the section “Implementation alternatives”.

[0088] A short description of the present invention is first presented before a detailed description of the drawings is provided. The present invention encompasses several key aspects to the existing level coding: the coding of the last significant scanning position, the removal of the FH250306PEP-2026098855. DOCX filing version PCT, rmbias from the signal prior to transform, the use of adaptive binarization strategies tailored to varying coding conditions, the specification of the number of “greater than” flags, the positiondependent context model sets, and modifications to the context modeling template to better reflect the statistical characteristics of biomedical signals, and which in turn, result in a higher compression efficiency.

[0089] In the following description a presentation of embodiments is provided. Before this, however, the description proceeds with a presentation of a possible framework or codec into which the embodiments described further below may be built into. Many details described in this framework are, however, optional when being combined with any of the subsequently described embodiments. To be more precise, the framework is described with respect to Fig. 1 which shows an encoder for encoding a multi-channel digital signal 14 into a data stream 16 as well as a decoder 12 for decoding the multi-channel digital signal 14 from the data stream 16. This description of Fig. 1 shall be seen as a presentation of new embodiments of the present application which result when combining any of the embodiments described subsequently with the decoder 12 or encoder 10 of Fig. 1 either by adopting all details / functionalities described with respect to Fig. 1 or with leaving-out some of the details / functionalities described with respect to Fig. 1. Sometimes such “optional” features of Fig. 1 are explicitly identified as being optional with respect to the combination of the subsequently described embodiments, but the just-mentioned possible combinations of the subsequently explained embodiments with the description of Fig. 1 shall not be restricted to these explicitly identified variations of Fig. 1 in terms of leaving-out certain features.

[0090] In Fig. 1, the multi-channel digital signal 14 is illustrated byway of an array of samples with the samples being illustrated as small squares 18. Each line / row corresponds to a certain channel of the multi-channel digital signal 14. Each channel of signal 14 may have associated therewith a respective channel ID and Fig. 1 shows these channels as being ordered according to their channel ID along vertical axis 20 which, thus, corresponds to a “source” channel axis 20. The horizontal axis 22 corresponds to time so that samples 18 forming one column, or being horizontally aligned, are samples belonging to one common time instant. Such set / column of temporally co-located samples 18 is illustrated in Fig. 1 at 24.

[0091] Each channel, thus, forms a digital time-varying signal or time / amplitude or time-to-amplitude signal. The multi-channel digital signal m might have been obtained by at least one of Electrocardiography, Electroencephalography, Electromyography or seismic measurement. Differently speaking, the multi-channel digital signal might be a bio-physiological waveform data such as an electroencephalography (EEG) signal, an electrocardiogram (ECG), or an FH250306PEP-2026098855. DOCX filing version PCT, rmelectromyography (EMG) signal, or seismic waveform data. However, each channel / signal might alternatively be another sort of waveform signal data such as scalar media data such as an audio signal and the signal 14 might be a multi-channel audio signal.

[0092] Fig. 1 illustrates the option according to which signal 14 is not coded directly, i.e., in the original domain 26, but in a so-called “coded domain” 28 which might differ from the original domain 26 by one or more of 1) channel transformation, 2) channel permutation and 3) temporal mutual channel alignment. The channel transformation, if applied, transforms, per sample time instant, a set or column 24 of samples from domain 26 to domain 28. Thus, in domain 28, the sample pitch and the time axis is the same as in domain 26, but the meaning of the channels is different, i.e., the “source” channels of domain 26 become transformed channels in domain 28. Accordingly, the vertical axis in Fig. 1 for domain 28 is denoted as 32. Note that the channel transformation might leave the number of channels unchanged so that there is the same number of channels in domain 26 as well as domain 28, but different approaches are also possible. Generally, the channel transformation would aim at reducing redundancy and trying to condense the channels’ energy onto a fewer number of channels in domain 28. As said, the channel transformation is optional. Accordingly, in general terms, the channels in domain 28 are called “coded channels” in order to distinguish them from the “original” or “source” channels of digital signal 14 in domain 26. The permutation is also optional and may be used in combination with, or without, the channel transformation. If used in combination with the channel transformation, the permutation may be performed prior to and / or or subsequent to the channel transformation in order to permute / sortthe source channels prior to transformation and the coded channels subsequent to the channel transformation. The channel transformation might be a DCT, DST, FFT or any other transformation. The temporal mutual alignment is also optional and might be seen as a constant temporal alignment between the source channels or the coded channels.

[0093] The module in encoder 10 performing the one or more of channel transformation, channel permutation and temporal mutual alignment is indicated in Fig. 1 as block 34. Side information 36 might be used in order to signal information on one or more of the following: 1) The channel transformation used, 2) information on the permutation(s) among the source channels and / or coded channels and 3) information on the mutual temporal alignment / delays between the source channels or coded channels wherein the temporal mutual alignment might be restricted to full sample precision. A corresponding block 38 in decoder 12 performs the reverse step, i.e., performs one or more of: 1) a channel retransformation, 2) a re-permutation of the source channels and / or coded channels and 3) a temporal re-alignment of the source channels or coded channels. Note, that if no channel transformation takes place, the coded channels are, FH250306PEP-2026098855. DOCX filing version PCT, rmin fact, equal to the source channels except for being temporally mutually aligned or being differently sorted due to permutation. Block 38 might be controlled by the before-mentioned side information 36.

[0094] Thus, the “actual coding” relates to the coded channels in domain 28. In the coded domain 28, the coded channels are depicted in Fig. 1 as lines or rows of samples 40, each extending along time axis 22, the coded channels being depicted one on top of the other along coded channel axis 32 - potentially ordered according to a coded channel ID they have associated therewith - so as to result into an array of samples 40. Again, although Fig. 1 depicts the case that the number of source channels equals the number of coded channels, the number might be different. Further, if channel transformation is used, while there is no longer a clear association between source channels on the one hand and coded channels on the other hand, the temporal association remains: For each temporally co-located samples 24, there is a corresponding temporally co-located set 42 of samples 40 of the coded channels, wherein the set 42 in domain 28 is a column and might be a set of horizontally mutually offset samples in case of, and according to, the mutual temporal alignment, if applied. In case of Fig. 1, it has been assumed that no such temporal alignment took place so that both sets 42 and 24 are pure columns in the time / channel representation.

[0095] The actual coding is done in units of so-called temporal blocks 30. The term “block” or “temporal block” 30 is used so as to denote both a temporal portion of the multi-channel signal in domain 28, i.e., the set of coded channels, as well as a temporal portion of a certain coded channel. That is, for each temporal block 30, each coded channel has a temporal block such as block 140 depicted for some temporal block 30c and same are mutually co-located. The coding is done sequentially along these blocks 140, by following a coding / decoding order, which traverses the blocks 140 temporal block 30 by temporal block 30 with traversing temporally co-located blocks of the coded channels along a channel order corresponding to the order of the coded channels along axis 32. This coding / decoding order is illustrated in Fig.

[0096] 1 at 60. That is, in case of temporal block 140 being the block currently to be coded / decoded, the previously decoded / encoded temporal blocks include all preceding temporal blocks of all coded channels as well as the temporally co-located temporal blocks of coded channels preceding the coded channel 92 of temporal block 140 in channel order. These previously coded / decoded temporal blocks and their samples are illustrated in Fig. 1 by way of shading. In this regard, note that in Fig. 1, merely one temporal block 140 has been illustrated explicitly in order to reduce the complexity of Fig. 1. Thus, in the specification herein, reference sign 140 is sometimes used to indicate the currently encoded / decoded temporal block or to stand representatively for all temporal blocks. Further, as depicted in Fig. 1, the partitioning of signal FH250306PEP-2026098855. DOCX filing version PCT, rm14 into temporal blocks 30 and 140, respectively, might be done in a manner so that these blocks 30 and 140, respectively, are non-overlapping.

[0097] The actual coding in units of the temporal blocks 140 is performed predictively. That is, the encoder 10 comprises a block predictor 62 which predicts the samples of the currently coded temporal block 140, thereby yielding a prediction signal 64, and the prediction residual 66 formed by a subtraction between the actual sample values of temporal block 140 and the predicted samples of prediction signal 64 formed at a subtractor 68 is coded into the data stream 16 by residual coder 70. The residual coding in residual coder 70 may, or may not, involve a coding error by means of quantization. In any case, block predictor 62 uses the reconstructable version as being available by previously coded temporal blocks in order to obtain the prediction signal 64. This reconstructable version 72 might be derived at encoder 10 by means of a residual decoder 74 which reverses, potentially under coding loss, such as quantization, e.g., by means of dequantization, the residual signal 76 as coded into data stream 16, and an adder 78 which sums-up prediction signal 64 and the reconstructable residual signal 80 as obtained by residual decoder 74. To be more precise, let’s call the channel-individual temporal blocks 140 subblocks with temporally collocated subblocks of all channels forming a temporal block 30. Then, the prediction in module 62 or, to be more precise, the prediction at encoder and decoder, is performed in units of the subblocks 140, i.e. subblock wise. The encoder is free to choose different prediction modes for the subblocks within one block 30. As explained in more detail herein, within one block 30, one subblock 140 may be predicted based on one or more subblocks previously - according to the decoding order 60 - en / decoded within this block 30, while another subblock 140 within that block 30 might be coded / decoded based on the previously en / decoded subblock 140 of the same channel (but within the previous block 30). The transform residual en / decoding is then performed subblock wise by use of a onedimensional transform signaled in the data stream as described hereinbelow.

[0098] The decoder 12 decodes the coded channels from data stream 16 in a corresponding manner, i.e., in units of the temporal blocks 30 or in temporal blocks 140, respectively, and using predictive decoding. To this end, the decoder 12 comprises a residual decoder 82, an adder 84 and a block predictor 86 which correspond to, and are mutually connected in the same manner as, elements 74, 78 and 62 of encoder 10. That is, the residual decoder 82 derives from the residual signal 76 in data stream 16 the reconstructable residual signal 80 for a currently decoded temporal block 140 which is then subject to addition with prediction signal 64 derived by block predictor 86 for temporal block 140 on the basis of the reconstructed version 72 of previously decoded temporal blocks at adder 84. The output of adder 84, thus, yields the reconstructed version 72 of the currently decoded temporal block 140 and becomes FH250306PEP-2026098855. DOCX filing version PCT, rmpart of the pool of already decoded samples of previously decoded temporal blocks when the temporal blocks of the coded channels are, in this manner, traversed along coding / decoding order 60 so as to reconstruct the coded channels in the coded domain 28.

[0099] Note that the above description concentrated on the so-called sample prediction where samples of a current block 140 are predicted based on reconstructed samples of one or more previously decoded blocks, but coding inter dependencies, namely intra-channel and interchannel coding dependencies may be exploited not only in terms of sample prediction, but also in terms of other coding tools involving, for instance, parameter prediction and / or context derivation.

[0100] In order to enable a high degree of random access capability, some of the temporal blocks 30 may be coded in a random access manner meaning that the coded channels therein are coded independent from previous temporal blocks 30. Imagine, for instance, that temporal blocks 30b and 30e are random access temporal blocks. Then, none of the temporal channel blocks 140 in temporal block 30b as well as 30e would depend on any preceding temporal block 140 and no coding dependency would cross these temporal blocks 30b and 30e, that is no temporal block 140 within any of temporal block 30b-30d would be coded depending on any block 140 temporally preceding temporal block 30b, and no temporal block 140 within any of temporal block 30e and following would be coded depending on any block 140 temporally preceding temporal block 30e.

[0101] Thus, in other words, coding dependencies are restricted so as to not reach-out beyond the border 96 of a random access temporal block 30b and 30e towards any preceding temporal block 30. Such restriction might also hold for intermediate temporal blocks 30c to 30d between random access temporal blocks 30b and 30e in that same may not depend on any temporal block preceding the leading one among the random access temporal blocks 30b and 30e, here block 30b. Accordingly, leading temporal borders 96 1of the random access temporal blocks 30b and 30e are indicated by bold lines in Fig. 1. In a variant, the restriction is not valid for all en / decoding stages. For instance, while the grouping might hold true for prediction, but the residual en / decoding dependencies might cross borders between channel groups. It might be the case, for instance, that for the entropy coding and decoding, all channels are coded jointly, i.e. using a single arithmetic coding engine, but that for the sake of prediction and reconstruction, the channels are grouped as described into independent groups such that, after entropy decoding, each such group can be reconstructed completely independently from each other group. This means that no prediction of sample values or any other information is supported between different channel groups.

[0102] FH250306PEP-2026098855. DOCX filing version PCT, rmFurther, it might be that the coding of the coded channels also interrupts or restricts interchannel dependencies. For example, one or more of the coded channels might be coded as random access coded channels so that same do not use inter-channel dependencies, but merely intra-channel dependencies. The restriction of inter-channel coding dependencies might follow the channel order 32: that is, coding of these random access coded channels and the intermediate coded channels therebetween would be restricted so as to not reach-out beyond such a random access coded channel toward any coded channel preceding that random access coded channel in channel order along axis 32. Two such random access coded channels 88a and 88b and the resulting inter-channel dependency borders are illustrated in Fig. 1. Note that the restriction of inter-channel dependencies might be differently and is illustrated here merely as an example where the definition of, along channel order 32, interspersed random access channels 88a and 88b defines channel groups covering contiguous channels along the channel order 32. Other groups of channels might be defined, which do not necessarily follow the channel order 32, and inter-channel dependencies might be restricted not to render any channel of one group dependent on a channel of any other group, and within each group the inter-channel dependencies may also by restricted or each channel might by coded inter-channel dependent on any previously coded channel within its channel group.

[0103] The block predictor 62 and 86 of encoder 10 and decoder 12, respectively, operate synchronously, i.e., they generate the same prediction signal 64 based on the previously encoded / decoded samples of previously encoded / decoded temporal blocks 140. On encoder side 10, the prediction for a certain temporal block 140 may be accompanied or determined by one or more prediction parameters. Same might be determined on encoder side based on a rate / distortion optimization. These prediction parameters 90 are coded into data stream 16 and they are decoded from data stream 16 and used by block predictor 86 so as to perform the same prediction.

[0104] It might be that encoder 10 and decoder 12 support more than one prediction mode. For instance, encoder 10 and decoder 12 may support an intra prediction mode (which mode may also be called block-copy mode) according to which the currently encoded / decoded temporal block 140 is predicted based on the reconstructed / reconstructable sample values of previously encoded / decoded temporal blocks of the same coded channel to which the currently encoded / decoded temporal block 140 belongs, which is coded channel 92 in the example of Fig. 1. Additionally or alternatively, encoder 10 and decoder 12 may support an inter-prediction mode (which mode may also be called cross-channel prediction mode) according to which the FH250306PEP-2026098855. DOCX filing version PCT, rmcurrently encoded / decoded temporal block 140 is predicted based on the reconstructed / reconstructable sample values of previously encoded / decoded temporal blocks of one or more coded channels preceding - in coding order 32 - the coded channel 92 to which the currently encoded / decoded temporal block 140 belongs. Additionally or alternatively, there may be a mixed prediction mode according to which the prediction signal 64 is obtained by both, reconstructed / reconstructable sample values of previously encoded / decoded temporal blocks of coded channel 92 itself as well as reconstructed / reconstructable sample values of one or more coded channels preceding coded channel 92 in channel order along axis 32. Beyond this, there may be temporal blocks 140 which are coded without any prediction at encoder 10 and decoded without any prediction at decoder 12 such as the first temporal blocks 140 in the tiles 94 resulting from mutually separating the temporal blocks by means of the random access borders 96 on the one hand and the random access channel borders 98 on the other hand. This corresponds to the prediction signal 64 being set to zero and this may form an additional mode which could be called bypass mode. Additionally, or alternatively, there may be other modes such as ones deriving a DC predictor or linear function predictor for block 64 based on immediately preceding samples which immediately precede block 140. The prediction parameters 90 may, thus, contain for a currently encoded / decoded temporal block 140 a prediction mode flag or prediction mode indicator indicating the prediction mode to be used for this currently encoded / decoded temporal block 140 and, optionally, one or more parameters parameterizing the prediction mode to be used for this currently encoded / decoded temporal block 140. It might also be that the prediction parameters are themselves coded predictively from already reconstructed blocks 140. In this prediction process, the laid out random-access capabilities in channel- and temporal-direction are, as an example, always maintained, i.e. the mentioned prediction of prediction parameters may never be supported across such a random access segment.

[0105] The aforementioned coding dependencies ought not to cross any of the borders 96 and 98 not only result from the just-described sample prediction capabilities of block predictor 62 and 86, respectively, but may optionally also result from other mechanisms such as parameter prediction according to which parameters such as the aforementioned prediction parameters 90 for a certain temporal block 140 are predicted based on coding parameters conveyed in the data stream 16 for any previous temporal block, or context derivation for context-adaptive entropy coding / decoding any coding parameter such as the prediction parameters 90 or any other side information such as side information 76 and 36 for temporal block 140 based on any coding parameter conveyed in the data stream 16 for any preceding temporal block.

[0106] FH250306PEP-2026098855. DOCX filing version PCT, rmThat is, summarizing, the encoder 10 encodes the multi-channel signal 14 by transferring it into the coded domain 28 and then coding the coded channels into data stream 16 in the just-described block-wise and predictive manner, wherein decoder 12 decodes the coded channels of coded domain 28 from data stream 16 and the corresponding block-wise and predictive manner with then gaining the multi-channel signal 14 in its original form 26 based on the coded channels in coded domain 28 by means of segment 38. As said, the channel transformation is optional and if not used, each sample 40 in the coded domain 28 really corresponds to one sample 18 in the original domain 26. If, further, the temporal mutual alignment is not used, each sample 40 exactly corresponds to a sample 18 in the original domain 26 at exactly the same time instant or, differently speaking, all temporally co-located samples 40 in coded domain 28 remain mutually temporally co-located in the original domain 26.

[0107] As mentioned before, Fig. 1 only represents a possible “framework” into which the embodiments described subsequently may be built into. Many modifications may be performed with respect to Fig. 1, and some of these modifications might be mentioned in the subsequent description with respect to certain ones of the subsequently described embodiments, but these modifications shall then be treated as being also applicable with respect to other ones of the subsequently described embodiments. Further, as a final note, and without being treated as forming an exclusive list of further possible amendments of the description of Fig. 1, it shall be noted that the temporal blocks 30 might, other than illustrated in Fig.1, vary in block length rather than being of a constant length as depicted in Fig. 1. For instance, encoder 10 may decide on the length of blocks 30 and signal a length parameter or the block length of blocks 30 (and the corresponding temporal blocks 140 of the coded channels) within data stream 16 and the decoder may be configured to set the length of blocks 30 based on the information provided by the data stream 16. Such signaling might be done on block level, such as for each temporal block 30 or, differently speaking for each temporally aligned bundle of blocks 140, so that the encoder may decide on the block size on the fly, or the block length might be signaled in the stream 16 on a larger scope such as for a sequence of blocks or even the whole data stream 16. According to an embodiment, the decoder 12 / encoder 10 is configured to switch between the different lengths of the temporal blocks at predetermined borders between consecutive temporal blocks according to the length parameter. Further, although not described before, it might be that residual coder and residual decoder 70 and 82 may use transform coding / decoding in order to convey the residual signal 76 in data stream 16. That is, the residual signal 80 may be conveyed in data stream 16 in transform or spectral domain by way of transform coefficients in residual signal 76. The transform domain might be a DCT, DST or an FFT. The transform may be non-overlapping, i.e. it may only transform residual signal 80 and its re-transform may only cover residual signal 76 within block 140, and / or may be non- FH250306PEP-2026098855. DOCX filing version PCT, rmwindowed, i.e. the residual signal might be transformed without any transform window used to temporally shape the residual signal 80 before the transform. The transform domain, i.e. the transformation leading from time domain to transform domain which is used by the encoder to transform the prediction residual signal 80 to be coded und the corresponding retransformation leading from transform domain to time domain which is used by the decoder to derive the prediction residual signal 80, or the transformation, might be selected from a set of available transforms including, for instance, one or more of 1) one or more DCTs, 2) one or more DSTs and 3) an identity transform according to which the prediction residual signal 80 is coded into the data stream 14 in time domain directly. The transform may be critically sampled in that the number of transform coefficients resulting from the samples of one block 140 may equal the number of samples of block 140. Again, the samples might be the residual samples or may be, in case of the bypass mode, the channel samples directly.

[0108] The transform coefficients might be encoded by quantization, i.e. they may be quantized with the quantized coefficients then being coded in the datastream 16. Dequantization may occur at decoding. For quantization, either a scalar uniform reconstruction quantizer or a low complexity vector quantizer might be used. In order to determine the quantization indices, the encoder may perform some optimization algorithm such as a rate-distortion optimized scalar quantization, or a trellis quantization with the goal to approximately minimize an approximated Lagrangian rate-distortion cost. At the decoder, the reconstruction process that yields the transform coefficients may be conducted by multiplying the coded quantization indices with a certain step-size and, in case of the use of a low-complexity vector quantizer, by additionally invoking a state-machine based on the parity of previously decoded quantization indices in order to reconstruct the current quantization index.

[0109] In order to control the quantization noise, the transform coefficients might be subject to noise shaping. Spectral noise shaping may be used to shape the quantization noise spectrally. This may be done by signaling in the data stream spectral-band scale factors, i.e. a scale factor per spectral band, which represent a transfer function of a spectral filter which approximates the spectral envelope of the signal within the current block 140 (or its prediction residual, respectively), or signaling filter coefficients defining a temporal filter having a filter transfer function which approximates the spectral envelope of the signal within the current block 140 (or its prediction residual, respectively). On encoder side, spectral noise shaping may be applied in spectral domain by multiplying an inverse of scale factors, either directly signaled in the data stream or derivable from the filter coefficients by filter-to-factor conversion, with the transform coefficients before quantization. That is, at encoder, the coefficients are shaped by the inverse of the spectral envelope. At decoder side, spectral shaping may be applied in FH250306PEP-2026098855. DOCX filing version PCT, rmspectral domain by multiplying scale factors, either directly signaled in the data stream or derived from the filter coefficients by filter-to-factor conversion, with the transform coefficients, with then. That is, at decoder, the coefficients are shaped by the spectral envelope before applying retransformation. Additionally or alternatively, temporal noise shaping might be applied. To this end, TNS filter coefficients might be determined and signaled by the encoder. The TNS filter coefficients may represent a transfer function which approximates the temporal envelope of the current block 140 (or its residual signal). The encoder may apply TNS filtering using the filter coefficients by spectrally filtering the possibly spectrally shaped transform coefficients so as to filter them with a transfer function corresponding to an inverse of the temporal envelope. The TNS filter coefficients might be derived by linear prediction analysis of the possibly spectrally shaped transform coefficients so as to derive a linear prediction filter, then used as TNS filter, which minimizes a prediction residual when spectrally applied on the possibly spectrally shaped transform coefficients. At the encoder, the TNS filtered coefficients are then quantized and entropy coded. At decoder side, the inverse takes place: the possibly spectrally shaped transform coefficients are inversely TNS filtered before applying retransformation. Additionally or alternatively, noise filling might be used. The filling may be applied to zero-quantized portions of the spectrum and controlled by the encoder via corresponding noise filling parameters.

[0110] As to the encoding / decoding the block or sequence of quantized transform coefficients of a current block into / from the data stream 16, arithmetic coding, such as context-adaptive binary arithmetic coding, CABAC, may be used. The CABAC encoding / decoding may by performed frame wise. That is, in each channel, the sequence of blocks 140 may be partitioned into immediately consecutive blocks 140, which form frames. This partitioning may be equal among the channels so that, again, a frame denotes both a temporal portion within each channel individually, as well as a temporal portion of the multi-channel signal, i.e. a collection of temporally aligned frames. Within each frame, the sequence of blocks 140 are CABAC en / decoded with once initializing the contexts and resetting the internal CABAC state at the beginning and then updating the contexts’ probabilities during en / decoding the respective frame. That is, blocks 140 are CABAC decodable merely in units of frames. The context initialization might be done independent from previous frames, or depending on the contexts as manifesting itself at the end of, of during, the en / decoding a previous frame.

[0111] Some deblocking processing might be used to avoid blocking artifacts. If, alternatively, an overlapped transform is used, an overlap-add processing with re-transforms of immediately preceding / succeeding temporal blocks of the same coded channel might be used in order to completely reconstruct the current temporal block’s 140 residual signal 76.

[0112] FH250306PEP-2026098855. DOCX filing version PCT, rmBesides such transform-(residual)-coded blocks there might be temporal blocks 140 which, additionally or alternatively, are coded using, besides the block prediction by block predictor 62 / 86 - which could be called a primary prediction - a secondary sample-wise prediction of the residual samples in residual block 66 such as by predicting a current sample’s residual sample by means of already decoded values of preceding - in sample coding order - residual samples in block 66 or 80, with then correcting same by means of a secondary-prediction-residual sample decoded from the data stream 16. The secondary-prediction-residual samples for such a block may coded into the data stream en block in a transform domain or samplewise in time domain.

[0113] Note that the afore-mentioned spectral shaping of the residual signal of a block 140 might be seen as a sample wise residual prediction, i.e. the case where filter coefficients are signaled for a block which define a temporal filter having a filter transfer function which approximates the spectral envelope of the residual signal within a current block 140. In sample wise residual prediction, the residual predictor on a current block 140 might either be chosen out of a fixed set of prediction modes, where an index to such a residual prediction mode is signaled in the bit-stream, or the residual prediction mode might be ‘signal adaptive’. In the latter case, prediction filter coefficients for the residual predictor are determined at the encoder by solving for example a linear equation, and are then quantized and transmitted to the decoder. At the decoder, the coefficients are inverse quantized and then the sample-wise prediction is conducted with these coefficients. The number of used coefficients may vary per block and might also be signaled in the bit-stream. Additionally, it might optionally (i.e. indicated by some information in the bit-stream) be supported to invoke collocated samples from a previous block for the sample wise residual prediction. Finally, the coefficients of the sample wise residual prediction might be coded predictively, i.e. be predicted from used coefficients of a previous block, where only the differences to the current coefficients are transmitted.

[0114] A final note shall be made with respect to the juxtaposition of frames, blocks 140, channels and channel groups and regarding decoding order. The description above already described the fact that the channels might be grouped into channel group with each channel group being coded independently from each other, meaning that the blocks 140 in a certain channel group are coded without dependencies from channels outside their channel group. The decoding order 60, thus, would traverse the channels channel-group individually, channel group by channel group. Within each channel group, the blocks 140 are traversed as described: all temporally aligned blocks 140 of all channels fist, then proceeding with the next blocks 140 and so forth. A frame may have a sequence of blocks of a channel group encoded thereinto FH250306PEP-2026098855. DOCX filing version PCT, rmalong the mentioned decoding order, such as n temporally consecutive blocks 140 for all channels of a channel group. IF the channel group had m channels, m*n block 140 would, thus, be coded into the frame. As mentioned, there might be dependent frames, for which the CABAC contexts are adopted from the preceding frame of the same channel group, i.e. the one having encoded the immediately preceding block 140. For such dependent frames, not only CABAC contexts may be adopted from the preceding frame, but it may also be allowed to allow for prediction from the preceding frame to the dependent frame. Prediction, and possibly also any coding dependencies, towards channels outside the channel group and, within the channel group, towards frames temporally preceding the mostly recently previously en / decoded independent frame would be disallowed. Thus, each tile shown in Fig. 1 by bold lines may represent a sequence of an independent frame flowed by zero, one or more dependent frames.

[0115] As mentioned before, Fig. 1 only represents a possible “framework” into which the previously described embodiments and the embodiments described subsequently may be built into. Many modifications may be performed with respect to Fig. 1, and some of these modifications might be mentioned in the subsequent description with respect to certain ones of the subsequently described embodiments, but these modifications shall then be treated as being also applicable with respect to other ones of the subsequently described embodiments.

[0116] The description is now resumed with respect to the announced subsequently described implementation examples and further embodiments where the digital time-varying signal is not restricted to be a channel of a multi-channel signal or to be a multi-channel signal, but where same may only be a single digital scalar signal.

[0117] Last Significant Position

[0118] Fig. 2 exemplarily depicts a schematic representation of a decoder 200 associated with coding of a last significant position, in accordance with embodiments.

[0119] As shown in Fig. 2, the decoder 200 for block-wise decoding of a digital time-varying signal, indicated by the reference numerals 28, 92 in connection to Fig. 1, from a data stream 16 is configured to predict 202 a last-position pointer 214 for a current block 140of the digital timevarying signal 28, 92 to obtain a last-position predictor 204. The decoder 200 is configured to decode 208 a last-position residual 210 from the data stream 16 and to correct 212 the lastposition predictor 204 using the last-position residual 210 to obtain a last-position pointer 214. The decoder 200 is configured to decode 234 first coefficients 218 of a transform 206 in an FH250306PEP-2026098855. DOCX filing version PCT, rminterval from a first coefficient 220 of the transform 206 to a coefficient 222 of the transform 206 pointed to by the last-position pointer 214 from the data stream 16 and infer that second coefficients 224 of the transform 206 have a predefined value 226 and to reconstruct 228 the current block 140using the transform 206. The decoder is configured to predict 20 the lastposition pointer 214 based on one or more last-position pointers 230 of further transforms 232 of previously decoded blocks 140 of the digital time-varying signal.

[0120] In regard to the prediction 202 by the decoder 200, it may be based on previously decoded last position pointers and / or it may be based on the current block 140. That is, the prediction could be based on, or depend on, merely the previously decoded last position pointers; merely the current block 140; or both the previously decoded last position pointers as well as the current block 140. The prediction 202 of the last-position pointer 214 for the current block 140is performed, or carried out, for obtaining (or, e.g. deriving, or determining) the last-position predictor 204. The last-position predictor 204 is corrected 212 using the last-position residual 210, decoded from the data stream 16, for obtaining a last-position pointer 214, for instance, by adding the last-position residual 210 to the last-position predictor 204.

[0121] For example, the first coefficients 218 (e.g. transform coefficients which may be significant) of the transform 206 may be decoded in an interval, or e.g. a set, which ranges (or e.g. spans) from a first coefficient (or, e.g. a first significant coefficient, or a first significant transform coefficient) of the transform 206 to the coefficient 222 (or, e.g. the last significant coefficient, or the last significant transform coefficient) of the transform 206 pointed to (or, e.g. indicated) by the last pointer pointer 214 from the data stream 16. That is, the set of first or significant transform coefficients 218 may comprise the first significant coefficient as well as the last significant coefficient. In this regard, the first and the last may be defined in relation to a specific decoding or scanning order to which the coefficients may be subjected, or it could be an order in terms of frequency, where the first coefficient 220 is associated with a smaller frequency compared to the coefficient 222 indicated or pointed to by the last-position pointer 214, or e.g. the last significant position. The decoder 200 infers (or e.g. determines or derives) that the second coefficients 224 (e.g. transform coefficients which may not be significant) have a predefined value 226.

[0122] For example, the transform 206 may form of (define) a (one-dimensional) sequence of coefficients (e.g., sequence of values in a transform domain, e.g., in a frequency domain), such as comprising the first 218 and the second coefficients 224. Subjecting a block to a transform function may yield a transform and subjecting a transform to a re-transformation function may yield a block. The (re-)transformation function may comprise one or more of a discrete cosine FH250306PEP-2026098855. DOCX filing version PCT, rmtransform (DCT), discrete sine transform (DST), and fast-Fourier transform (FFT).

[0123] In accordance with embodiments, the second coefficients 224 of the transform 206 may be in an interval, or e.g. a set, from a coefficient following (or e.g. subsequent to, or succeeding, or immediately subsequent to, or immediately succeeding) the coefficient 222 of the transform 206 pointed to, or e.g. indicated, by the last-position pointer 214 to a last (e.g. final) coefficient of the transform. That is, there may be no more coefficients of the transform 206 which succeed or follow the last coefficient. For example, in accordance with embodiments, the predefined value associated with the second coefficients 222 may be zero.

[0124] In accordance with embodiments, the decoder 200 may be configured to predict 202 the lastposition pointer 214 based on at least one of the following:

[0125] a) one or more last-position pointers 230 of further transforms 232 of previously decoded blocks 140 of the digital time-varying signal in a channel of the current block 140, and

[0126] b) one or more last-position pointers 230 comprising, for each of one or more channels preceding the channel of the current block 140, a last-position pointer 230 of a further transform 232 of a previously decoded block 140 of the digital time-varying signal in the respective channel preceding the channel of the current block 140.

[0127] In addition to the above, the prediction 202 of the last-position pointer 214 may be based on additionally taking into account at least one of the following: a block size of the current block 140nd one or more block sizes of the previously decoded blocks 140.

[0128] For example, in relation to the one or more last-position pointers 230 of further transforms 232 of previously decoded blocks 140 of the digital time-varying signal in a channel of the current block 140could be last-position pointers of transforms (e.g. further transforms 232) of previously decoded blocks 140, which are arranged in the same channel as the current block 140. For example, the one or more of the last-position pointers could be p1,0to p1,0, like p2,0and / or p^1,0as depicted in Fig. 2, of the channel denoted with index 0, wherein the current block 140is also positioned in channel 0. That is, the index i could indicate a previous of the last-position pointers 230 of the further transforms 232. For example, the last-position pointer 214 of the transform 206 of the current block 140may be denoted p '°.

[0129] For example, in relation to the one or more last-position pointers 230 comprising, for each of one or more channels preceding, or previous to, the channel of the current block 140, the lastposition pointer 230 of the further transform 232 of the previously decoded block 140 of the FH250306PEP-2026098855. DOCX filing version PCT, rmdigital time-varying signal in the respective channel preceding the channel of the current block 140, the one or more of the last-position pointers could

[0130]

[0131] be to p '-1, like p '-1as depicted in Fig. 2, of the channel denoted with index -1, wherein the current block 140is positioned in channel 0. For example, the last-position pointer 214 of the transform 206 of the current block 140may be denoted p '°. Additionally, in accordance with embodiments, the previously decoded block 140 of the digital time-varying signal in the respective channel preceding the channel of the current block 140may represents a co-located block of the current block, for example which could be a temporally co-located block. For example, the previously decoded block 140 may refer to a block in a previously decoded channel that corresponds to the same temporal position as the current block 140in the current channel (i.e. the channel of the current block). Thus, the previously decoded block 140 in the respective channel preceding the channel of the current block 140may be mutually co-located, such as temporally, with the current block 140. For example, the previously decoded block 140 and the current block 140may be temporally aligned.

[0132] In accordance with embodiments, the decoder 200 may be configured to predict 202 the lastposition pointer 214 based on one or more last-position pointers 230 of further transforms 232 of previously decoded blocks 140 of the digital time-varying signal by filtering the one or more last-position pointers 230 of the further transforms 232 of the previously decoded blocks 140 of the digital time-varying signal. That is, for example, the decoder 200 may subject the one or more last-position pointers 2320 of the further transform 232 to a filter, and thus the filtered pointers, such as among the one or more last-position pointers which meet a filtering criterion associated with the filtering of the one or more last-position pointers, may be used for prediction 202 of the last-position pointer 214. In accordance with embodiments, the filtering of the one or more last-position pointers 230 of the further transforms 232 of the previously decoded blocks 140 of the digital time-varying signal could depend on, or e.g. be based on or contingent on, at least one of the following:

[0133] a) a prediction mode for predicting the last-position pointer 214 for the current block 140of the digital time varying signal, and

[0134] b) a transform mode associated with the transform 206.

[0135] That is, the filtering could be subjected to depend on merely the prediction mode, or merely the transform mode, or both the prediction mode and the transform mode.

[0136] In accordance with embodiments, the decoder 200 may be configured to decode 208 the lastposition residual 210 from the data stream 16 using delta decoding. For example, in accordance with embodiments, the last-position residual 210 may be delta decoded, i.e. decoded 208 in accordance with delta-decoding, relative to last-position residuals of the one FH250306PEP-2026098855. DOCX filing version PCT, rmor more last-position pointers 230 of the further transforms 232 of the previously decoded 140 of the digital time-varying signal. For example, in accordance with embodiments, the lastposition residual 210 may comprise a magnitude as well as a sign.

[0137] In accordance with embodiments, the decoder 200 may be configured to check whether the data stream 16 comprises, or contains, any indications (e.g. one or more indications) pertaining to, or for, suppression of prediction 202 of the last-position pointer 214 for the current block 140of the digital time varying signal 28, 92 from the data stream to obtain the last-position predictor 204. Additionally, in accordance with embodiments, if (or, e.g. when) the data stream 16 comprises, or contains, any indications (e.g. one or more indications) pertaining to, or for, the suppression of prediction 202 of the last-position pointer 214, the decoder may be configured to infer (or e.g. derive or determine) that the last-position predictor 204 may be zero and to not predict 202 (e.g. forbid prediction 202) of the last-position pointer 214 for the current block 140of the digital time varying signal 28, 92 from the data stream 16 to obtain the lastposition predictor 204. That is, depending on the presence of indications for suppression of prediction 202 of the last-position pointer 214 for the current block, the decoder may infer the last-position predictor 204 to be zero and to skip prediction 202 of the last-position pointer 214.

[0138] Additionally, in accordance with embodiments, in case (e.g. if or when) the data stream 16 may indicate, i.e. or comprise indications, to suppress predicting 202 the last-position pointer 214, the last-position residual comprises a magnitude and no sign. That is, for example, when the prediction of the last-position pointer 214 may be skipped or suppressed, the corresponding last-position residual may comprise only a magnitude without a sign.

[0139] In accordance with embodiments, the decoder 200 may be configured to decode 208 the lastposition residual 210 from a data stream 16 using context-adaptive entropy decoding. Additionally, in accordance with embodiments, a context model for the context-adaptive entropy decoding may depend on statistical properties of the last-position pointer. For example, the statistical properties of the last-position pointer may be related to the statistical properties of a digital time-varying signal coded in the data stream. For example, the statistical properties of the last-position pointer may be, or may comprise, statistical properties of a biomedical waveform signal.

[0140] In accordance with embodiments, for example, the decoder may be configured to choose, or e.g. select, a context model for the context-adaptive entropy decoding dependent on the one or more last-position pointers 230 of the further transforms 232 of the previously decoded blocks 140 of the digital time-varying signal.

[0141] FH250306PEP-2026098855. DOCX filing version PCT, rmIn accordance with embodiments, the coding of the last significant position pL, such as the coefficient 222 pointed to or indicated by the last-position pointer 214, is performed using delta coding, relative either to the previous block, such as previously decoded block 140, in the same channel pl, such as a same channel as the current block 140, and / or the corresponding block, e.g. which could be a temporally co-located block as the current block 140, in a previous channel p, such as a channel preceding or being previous to the channel of the current block. Alternatively, the position, such as the last-position pointer 214, can be predicted by filtering a set of previously observed last significant positions (f pl, pl, pl,...)), e.g. one or more lastposition pointers 230 of further transforms 232 of previously decoded blocks 140, potentially depending on the current prediction and / or transform mode. As a fallback, a default prediction value may be used to indicate that no predictor is applied, in which case the position is signaled using the state-of-the-art method, i.e., without including a sign when no predictor is active. Another configuration for the usage of a predictor is the current block size, e.g., the predictor is only employed when the block size is greater than a defined (e.g. predetermined) limit.

[0142] Regardless of the prediction method — or even when no prediction is used — the coding process itself may follow an approach similar to level coding, but with dedicated context models specifically designed for last position prediction. Alternatively, the existing context modeling is employed for signaling the last significant position, while when coding as a delta value, an additional sign bin is signaled using the bypass mode.

[0143] Bias Removal

[0144] Fig. 3 exemplarily depicts a schematic representation of a decoder 300 associated with bias removal coding, in accordance with embodiments.

[0145] As shown in Fig. 3, the decoder 300 for block-wise decoding of a digital time-varying signal, indicated by the reference numerals 28, 92 in connection to Fig. 1, from a data stream 16 is configured to decode 302 an offset value 304 for a current block 140of the digital time-varying signal 28, 92 from the data stream 16, to decode 306 a transform 206 of the current block 140from the data stream 16 and to reconstruct 228 the current block 140using the transform 206 in a form offset-compensated 308 using the offset value 304.

[0146] For example, the offset value 304 for the current block 140may be associated with a bias of a residual signal decoded from the data stream 16, or with a bias of one or more transform coefficients associated with a residual signal decoded from the data stream. Therefore, the FH250306PEP-2026098855. DOCX filing version PCT, rmreconstruction of the current block 140by the decoder is performed in a manner which uses the transform 206 in a form which is offset-compensated using the offset value. By offset-compensated, it is meant that the decoder 300 may adapt, or adjust, or modify the transform 206, such as a block, or as a block of transform coefficients constituting the transform 206, based on the decoded offset value 304. By this measure, the transform 206 is brought into an offset-compensated form 308 by using the offset value in the course of reconstructing the current block 140. That is, the transform 206 may be suitably modified or adjusted or scaled so as to compensate for the decoded offset value 304.

[0147] Additionally, in accordance with embodiments, the decoder 300 may be configured to read an offset present flag, e.g. an indicator for indicating a presence of the offset value 304 in the data stream 16, from the data stream 16. In the case that (or, e.g. if, or when) the offset present flag indicates that the offset value 304 is present for the current block 140, the decoder may be configured to decode 302 the offset value 304 for the current block 140of the digital timevarying signal 28, 92 from the data stream 16. Additionally, in the case that (or, e.g., if, or when) the offset present flag indicates that the offset value 304 is not present for the current block 140, the decoder may be configured to infer (or, e.g. derive, or determine) that the offset value 304 for the current block 140of the digital time-varying signal 28, 92 is zero. That is, for example, when the offset present flag indicates an absence of the offset value 304 for the current block 140, the decoder may infer that the offset value 304 for the current block has a default value, which, for example, could be zero, but could also be a pre-defined or a predetermined value. For instance, this pre-defined or predetermined value may be zero in accordance with some embodiments but could also be a non-zero value in accordance with alternative embodiments.

[0148] In accordance with embodiments, for example, in the case that (or, e.g., if, or when) the offset present flag indicates that the offset value 304 is indeed present for the current block, the decoder 300 may be configured to decode the offset value 304 for the current block of the digital time varying signal 28, 92 from the data stream 16 using a 0th-order Exponential-Golomb code. That is, for example, the offset value 304 may be coded into the data stream using the 0th-order Exponential-Golomb code.

[0149] In accordance with embodiments, for example, in the case that (or, e.g., if, or when) the offset present flag indicates that the offset value 304 is indeed present for the current block, the decoder 300 may be configured to decode the offset value 304 for the current block of the digital time varying signal 28, 92 from the data stream 16 using an equiprobability mode. For example, the equiprobability mode may be a bypass mode. For example, in regard to the FH250306PEP-2026098855. DOCX filing version PCT, rmequiprobability mode, the plurality of bins associated with the binarization of the 0th-order Exponential-Golomb mode may each be assigned equal probability.

[0150] Further, in accordance with embodiments, the decoder 300 may be configured to read, or e.g. decode, the offset present flag from the data stream 16 using context-adaptive entropy decoding.

[0151] In accordance with embodiments, in the course of decoding 302 the offset value 304 for the current block 140of the digital time varying signal 28, 92 from the data stream 16, the decoder 300 may be configured to read a quantized offset value from the data stream and dequantize the quantized offset value. That is, for example, the offset value 304 may be decoded from the data stream in a quantized form in accordance with a quantization scheme, information pertaining to which may be available or derivable from the data stream for the decoder. This quantized form of the offset value 304 may be subject to a dequantization, or an inverse quantization operation, in harmony with the quantization to which the quantized offset value was subjected to.

[0152] In accordance with embodiments, the decoder 300 may be configured to decode 306 the transform 206 of the current block 140from the data stream 16 by decoding 234 coefficients 216 of the transform 206. The decoder 300 may be configured to combine the offset value 304 and the coefficient 216 of the transform, such as by using a combiner. For example, the decoder 300 may be configured to add, or perform an addition of, the offset value 304 to the coefficients 216 of the transform 206 after applying an inverse transformation, being inverse in relation to the transform 206, to the transform 206 to obtain the transform 206 in a form which is offset-compensated 308. By this measure, the offset value can be taken into account in obtaining the transform for the decoder side 300, and bias removal may be achieved. For example, the inverse transform may be an inverse lifting-based Discrete Cosine Transform. That is, in accordance with embodiments, in course of decoding the transform 206 of the current block 140, the decoder 300 may be configured to apply an inverse lifting-based Discrete Cosine Transform to the transform 206 (e.g. onto the block of transform described by the transform 206) before adding the offset value 304 to obtain the transform 206 in a form which is offset-compensated 308.

[0153] In accordance with embodiments, for example, the offset value 304 may be associated with a mean, or e.g. an average value, of the current block 140. In this regard, for example, the mean or the average value may be a mean or an average value in frequency space / domain. For instance, the mean or the average value may be a mean or an average value of a whole of the FH250306PEP-2026098855. DOCX filing version PCT, rmset of the transform coefficients described the transform block 206. That is, for example, the offset value may be associated with, or related to, a DC component of the current block, which for example may be an encoded block.

[0154] In connection with the above described embodiments described using the depiction of Fig. 3, details are now provided which explain the advantages of the above described embodiments. The use of a lifting-based Discrete Cosine Transform (DCT) approximation may become inefficient in scenarios where no prediction is applied or where the prediction is suboptimal. This may lead to a significant bias in the residual signal, which is expressed by a huge absolute DC coefficient. In such cases, it is advantageous to remove the mean (DC component), such as the offset value 304 being or being related to the mean or DC component, from the signal, e.g. the digital time-varying signal 28, 92 in the data stream 16, in the spatial domain prior to transform 206, and to add it back after the inverse transform. This removed bias value, e.g. offset value 304 for a current block 140, is quantized and signaled separately in the bitstream, e.g. data stream 16.

[0155] The coding of the bias is handled using dedicated context models. For instance, one configuration uses a single context model to signal whether the mean is non-zero. If it is nonzero, the remaining value is encoded using a Oth-order Exponential-Golomb code, with all bins in this binarization encoded in bypass mode. Similar to the coding of the last significant position described in connection to Fig. 2, the bias removal may be active only for certain prediction modes, e.g., when there is no prediction at all, and / or for a given block size. That is, for example, the offset value coding may depend on at least one of: a prediction mode or a block size of the current block 140or block sizes of the previously decoded blocks.

[0156] Adaptive Binarization

[0157] Fig. 4 exemplarily depicts a schematic representation of a decoder 400 associated with adaptive binarization, in accordance with embodiments.

[0158] As shown in Fig. 4, the decoder 400 for block-wise decoding of a digital time-varying signal, indicated by the reference numerals 28, 92 in connection to Fig. 1, from a data stream 16 is configured to decode 306 a transform 206 of a current block 140of the digital time-varying signal 28, 92 from the data stream 16 and to reconstruct 228 the current block 140using the transform 206. The decoder 400 is configured to decode 401 each of coefficients 402 of the transform 206 by decoding 404 a bin string 406 of one or more bins from the data stream 16, by debinarizing 408 the bin string 406 to obtain a quantization level 410 of the respective FH250306PEP-2026098855. DOCX filing version PCT, rmcoefficient 402 and by dequantizing 412 the respective coefficient 402. The decoder 400 is configured to select 414 a binarization scheme 416 out of a set 418 of predefined binarization schemes 420 for at least one of the coefficients 402 depending on one or more previously decoded coefficients 424 of the transform of the current block and / or on a characteristic 422 of one or more previously decoded blocks of the digital time-varying signal 28, 92. In other words, the selection 414 of the binarization scheme 416 out of the set 418 of predefined binarization schemes 420 may be performed for the at least one of the coefficients 402 merely based on one or more previously decoded coefficients 424 of the transform 206 of the current block 140, or merely based on the characteristic 422 of the one or more previously decoded blocks of the digital time varying signal 28, 92 or being based on both the one or more previously decoded coefficients 424 of the transform 206 of the current block 140nd the characteristic 422 of the one or more previously decoded blocks of the digital time varying signal 28, 92.

[0159] For example, the decoder 400 may decode coefficients 218 of the transform 206 of the current block 140. The transform 206 may, for example, represent the current block in the transform domain, such as in the frequency domain.

[0160] For example, the set of predefined, or predetermined, binarization schemes 420 for at least one of the coefficients 402 out of which the binarization scheme 416 is selected may be coded in the data stream 16. The selection of the binarization scheme 416 is carried out for the at least one of the coefficients 402 which depends on one or more previously decoded coefficients 424 of the transform 206 of the current block. Additionally, or alternatively, the selection of the binarization scheme 416 is carried out for the at least one of the coefficients 402 which depends on a characteristic 422 of one or more previously decoded blocks of the digital time-varying signal 28, 92 in the data stream 16.

[0161] Additionally, in accordance with embodiments, the decoder 400 may be configured to decode a last-position pointer 214, as exemplarily described in connection to Fig. 2, for a current block 140of the digital time-varying signal 28, 92 from the data stream 16. The coefficients 402 of the transform 206 may be positioned within an interval from a first coefficient 220 of the transform 206 to a coefficient 222 of the transform 206 pointed to by the last-position pointer 214. Since details relating to first coefficient 220, the coefficient 222 and the last position pointer 214 have already been described in detail in connection to Fig. 2, such details and explanations are not repeated here for the sake and brevity of this disclosure. Rather, such details and explanations are to be configured so as to apply onto the decoder 400 associated with adaptive binarization in connection to Fig. 4, as described already.

[0162] FH250306PEP-2026098855. DOCX filing version PCT, rmIn accordance with embodiments, for example, the predefined binarization schemes 420 may comprise a first binarization scheme 419i and a second binarization scheme 4192, as exemplarily depicted as comprised in the block 418 denoting the set of pre-defined binarization schemes. For example, the first binarization scheme 419i may be composed of a significance flag 425 indicating whether coefficient significance applies followed by, in case of coefficient significance applies, a level bin string indicative of a coefficient’s absolute value. For example, the second binarization scheme 4192 may be composed of a significance flag 425 indicating whether coefficient significance applies followed by, in case of coefficient significance applies, a parity bit 427 indicative of a coefficient’s parity and a level bin string indicative of a remainder of the coefficient’s absolute value divided by two.

[0163] Additionally, in accordance with embodiments, the decoder 400 may be configured to decode the last-position pointer 214 for the current block 140of the digital time-varying signal 28, 92 from the data stream 16, wherein the coefficients 402 of the transform 206 are positioned within an interval from a first coefficient 220 of the transform 206 to a coefficient 222 of the transform 206 pointed to by the last-position pointer 214, and may infer, or e.g. derive or determine, that the significance flag 425 indicates significance for the coefficient 222 of the transform 206 pointed to by the last-position pointer 214.

[0164] In accordance with embodiments, the decoder 400 may be configured to switch from the first binarization scheme 419i to a second binarization scheme 4192 of the predefined binarization schemes 420 for coefficients 402 of the transform 206 of the current block 140 yet to be decoded when a currently decoded coefficient whose quantization level 410 is obtained using the first binarization scheme exceeds a predetermined threshold. That is, for example, the decoder 400 may configured to switch or change from one binarization scheme to other binarization scheme among the binarization schemes 419i, 4192for those coefficients of the transform 206 which have not yet been decoded based upon or subject to the condition or the constraint that the quantization level of the currently decoded coefficient, whose quantization level has been obtained using one (e.g. one being the first 419i) of the binarization schemes out of the set 418 of the binarization schemes 420, exceeds, or is greater, than a predetermined threshold (e.g. a predetermined quantization level threshold). That is, the decoder 400 may switch from the first binarization scheme 419i to the second binarization scheme 4192 provided the quantization level of the currently decoded coefficient, obtained using the first binarization scheme 419i, is larger than a predefined or predetermined threshold. In alternative scenarios, for example, the switch may be carried out from the second

[0165] FH250306PEP-2026098855. DOCX filing version PCT, rm4192 to the first 419i when the quantization level exceeding a predetermined threshold has been obtained using the second binarization scheme 4192.

[0166] Additionally, or alternatively, the decoder 400 may be configured to select among the predefined binarization schemes 420 for a current coefficient depending on a sum value derived (or e.g. calculated, or computed) based on, or, e.g. using, one or more previously decoded coefficients of the transform 206 of the current block 140or bins decoded so far (e.g. already decoded bins or previously decoded bins) for the one or more previously decoded coefficients of the transform 206 of the current block 140.

[0167] In connection with the above described embodiments described using the depiction of Fig. 4, advantages resulting from implementations of the decoder 400 are now described. The statistical characteristics of biomedical signals differ markedly from those of natural video or audio. Notably, the distribution of absolute levels in biomedical data is often highly skewed, closely resembling a geometric distribution with a parameter near 1, if one considers the geometrical distribution is still an appropriate fit of the empirical data. This presents challenges for conventional entropy coding methods, which typically assume more balanced or less sparse distributions.

[0168] A key observation when analyzing absolute level distributions within a block is the presence of a sparse tail — a large portion of the block, contains mostly zero-valued coefficients. In contrast, the beginning of the block tends to exhibit levels with high absolute magnitudes.

[0169] To effectively handle this distribution, this invention, as described in connection to Fig. 4, introduces an adaptive binarization strategy. Specifically, a secondary binarization scheme, such as indicated by reference numeral 419, is employed under certain conditions. After coding the significance flag, such as indicated by reference numeral 425, a parity flag, such as indicated by reference numeral 427, is signaled only for each significant position in the alternative binarization. This enables the remaining absolute level value to be halved, thereby reducing the magnitude range that has to be coded and improving overall compression efficiency.

[0170] The condition that triggers this switch in binarization can be based on either:

[0171] • The magnitude of a coded absolute value exceeding a predefined threshold (with the switch maintained thereafter), or

[0172] • The template sum used in context modeling exceeding a certain threshold.

[0173] FH250306PEP-2026098855. DOCX filing version PCT, rmThis adaptive approach allows the coding process to better match the actual statistics of biomedical signals, thereby improving compression efficiency. A dedicated set of context models may be employed for the coding of the parity flag and the bins belonging to the second binarization scheme. Note that the position-dependent context model sets, applied to the coding of the significance flag and the bins belonging to the truncated unary code may also employ context models different than those used for the first binarization scheme.

[0174] Number of “Greater Than” Flags

[0175] Fig. 5 exemplarily depicts a schematic representation of a decoder 500 associated with coding of a number of “greater than” flags, in accordance with embodiments.

[0176] As shown in Fig. 5, the decoder 500 for block-wise decoding of a digital time-varying signal, indicated by the reference numerals 28, 92 in connection to Fig. 1, from a data stream 16 is configured to decode 306 a transform 206 of a current block 140of the digital time-varying signal 28; 92 from the data stream 16 and to reconstruct 228 the current block 140using the transform 206. The decoder 500 is configured to decode 401 each of significant coefficients 502 of the transform 206 by decoding 504 a number n of greater-than bins (e.g. greater-than flags) gtj with 0<i<n+1, indicating whether an absolute quantization level of the respective significant coefficient 502 is greater than i, and determine n for at least one of the significant coefficients 502 depending on one or more previously decoded coefficients 524 of the transform of the current block and / or a characteristic 522 of one or more previously decoded blocks of the digital time-varying signal 28, 92.

[0177] That is, for example, the decoder 500, in course of decoding 401 each of the significant coefficients 502 of the transform 206, decodes 504 a number n, e.g. a count or an enumeration, of greater-than bins, denoted by gtj, wherein i may range from being greater than 0 to being less than n+1. The greater-than bins indicated whether, or if, the absolute quantization level of the significant coefficient associated with the respective bin is greater, or larger, than i. The decoder 500 determines the enumeration, or the count, or the number n of such greater-than-bins. This determination is carried out at least one of the significant coefficients 502 based on merely the at least one significant coefficient depending on the one or more previously decoded coefficients (e.g. already decoded coefficients) of the transform block 206, or merely the at least one significant coefficient depending on the characteristic 522 of one or more previously decoded blocks of the digital time-varying signal 28, 92, or being based on both the at least one significant coefficient depending on the one or more previously decoded coefficients (e.g. already decoded coefficients) of the transform block 206 and the at least one significant FH250306PEP-2026098855. DOCX filing version PCT, rmcoefficient depending on the characteristic 522 of one or more previously decoded blocks of the digital time-varying signal 28, 92.

[0178] For example, the decoder 500 may decode the number n of greater-than bins for at least one of the significant coefficients depending on a block size of the current block 140nd / or the prediction mode used to generate or predict the residual signal.

[0179] For example, the decoder 500 may decode coefficients 218 of the transform 206 of the current block 140. The transform 206 may, for example, represent the current block in the transform domain, such as in the frequency domain.

[0180] By this measure, a dynamic determination of a number of threshold, such as defined by the number of greater-than bins, is achieved. Further, an adaptive coding of the number of thresholds is also achieved.

[0181] In connection with the above described embodiments described using the depiction of Fig. 5, advantages resulting from implementations of the decoder 500 are now described. The number of thresholds, defined by the number of greater-than flags used in the truncated unary binarization of absolute levels, is typically fixed and optimized for high coding efficiency. However, this parameter is highly dependent on the coding conditions under which the encoder operates, and therefore, it can be more effective if adaptively selected based on signal statistics. In the embodiments described in connection with Fig. 5, the actual number of thresholds may be determined dynamically based on the template sum calculated during context modeling for the significance flag. Alternatively, the thresholds may depend on the current block size and / or the prediction mode used to generate the residual signal.

[0182] Position-Dependent Context Model Sets

[0183] Fig. 6 exemplarily depicts a schematic representation of a decoder 600 associated with position dependent context sets, in accordance with embodiments. Fig. 7 exemplarily depicts a schematic representation of an implementation of position dependent context selection for coefficients at different positions within current blocks of different sizes, in accordance with embodiments. Fig. 8 exemplarily depicts a schematic representation of implementations of threshold for context model sets for current blocks of different sizes, in accordance with embodiments.

[0184] As shown in Fig. 6, the decoder 600 for block-wise decoding of a digital time-varying signal 28, 92 from a data stream 16 is configured to decode a transform 206 of a current block 140of the FH250306PEP-2026098855. DOCX filing version PCT, rmdigital time-varying signal 28, 92 from the data stream 16 and reconstruct 228 the current block 140using the transform 206. The decoder 600 is configured to, in decoding the transform 206 from the data stream 16, context-adaptively entropy decode coefficients 602 of the transform 206 from the data stream 16 and select 606 the context set Cseifor the context-adaptive entropy decoding of the coefficients 602 of the transform 206 from the data stream 16.

[0185] For example, the decoder 600 may decode coefficients 218 of the transform 206 of the current block 140. The transform 206 may, for example, represent the current block in the transform domain, such as in the frequency domain.

[0186] As depicted in Fig. 6, the context-adaptive entropy decoding may be carried out based on selecting 606 the context set Cseifrom, or out of, a collection 604 of a plurality of context sets. A number of the plurality of different context sets is denoted by m and the index sei denotes a specific selected context set. Since the number of context sets is m, the selection index sei may range from 0 to m+1. That is, the context set Cseiis selected out of the collection 604 of m context sets Ci with 0<i,sel<m+1. Here is i is an index to generically describe the ith context set of the set of m context sets. Thus, the decoder 600 entropy decodes 608 the currently decoded coefficient 610 using a context selected 612, or chosen, out of, from, the selected context set Csei. The selection 606 of the selected context set Cseifrom the m context set is now further described in connection to Fig. 7.

[0187] The decoder 600 is configured to select 606 the context set Csei by selecting a set of m thresholds, denoted by tj,s, wherein the index i is associated with the context set Ci and the index s is associated with the block size s. The threshold values for a block size s, are defined as follows: to,s=O and tm,s=2s-1. The threshold values are further selected to be monotonically increasing for all i, i.e. tj-i,s<ti,sfor all i depending on a size 2sof the current block 140. The block size s is between smin and smax- That is, the block size s may range from smin to smax, where both Smin and smax are included in the range of block size s, i.e. e.g., both inclusive, smin2s<smax. In addition to the selection of the set of m thresholds tiiS, the selection 606 of the context set Csei comprises selection of sei such that a coefficient position j of the currently decoded coefficient falls into an interval [tsei-i,s,tSei,s]- This is exemplarily depicted in Fig. 7, where the number of context sets m is exemplarily set equal to g.

[0188] In the three exemplary scenarios depicted in Fig. 7, context set selection for different block sizes s1, s2, s3 is shown with in an ascending order in increase of block sizes, i.e. Si< S2< S3. For example, sei = 4 is selected where the block size is Si in a manner where the coefficient position j of the currently decoded coefficient falls into the interval [t3,si,t4,si]. For example, sei FH250306PEP-2026098855. DOCX filing version PCT, rm= 8 is selected where the block size is S2 in a manner where the coefficient position j of the currently decoded coefficient falls into the interval [t7,s2,t8,s2]. For example, sei = 9 is selected where the block size is S3 in a manner where the coefficient position j of the currently decoded coefficient falls into the interval [ts,s3,t9,s3].

[0189] The selection of thresholds is now described in connection to Fig. 8. The thresholds tj,sare selected so that:

[0190] 1) ti,s-tj-i,smonotonically increases for i for all smin s s < smax, and

[0191] 2) there exists at least one Sthres with smin^ Sthres < smax and ithres with 0 < ithres < m, so that:

[0192] • ti_above,s_above-ti_above-1,s_above iS greater than ti_above-1,s_above -ti_above-2,s_above, and

[0193] • ti_above,s_above-ti_above,s_above-1 iS greater than ti_above,s_above-1-ti_above,s_above-2 for all m+1 > iabove — ithres and all Smax — Sabove — Sthres-

[0194] An exemplary choice of Sthres being equal to 9 and ithres being equal to 3 is depicted in Fig. 8. The configuration of the thresholds as shown in Fig. 8 fulfill the selection criterion 1) and 2) as detailed above. With smin = 2 and smax=14, the configuration of Fig. 8 depicts a monotonic increase of tj,s-tj-i,s, i.e. for a specific block size s, the difference between a current threshold tj,sand the immediately previous threshold tj-i,sincreases monotonically for i for all s belonging to the set [Smin, smax]. Further, the existence of at least one Sthres and at least one ithres fulfilling the conditions specified in 2) above are shown in Fig. 8.

[0195] Further, in accordance with embodiments, the decoder 600 may be configured to context-adaptively entropy decode coefficients 602 of the transform 206 at least with respect to a significant flag of the coefficients 602. That is, the significance flag of the coefficients 602 may be taken into account by the decoder 600 in context-adaptive entropy decoding of the coefficients 602.

[0196] For example, in accordance with embodiments, each of the context sets Ci may have the same number of contexts. That is, for example, each context set of the context sets Ci may be mutually disjoint with respect to each other.

[0197] For example, in accordance with embodiments, the decoder 600 may be configured to select the context out of the selected context set Cseibased on the sum t of previously decoded coefficients in a template.

[0198] FH250306PEP-2026098855. DOCX filing version PCT, rmIn conventional designs, context model classes based on position are fixed and optimized for a single block size, yet applied universally across all block sizes. In the embodiments described in connection with Fig. 8, the quantization of positions remains consistent with the state-of-the-art approach, allowing for nine context model sets, as traditionally used. However, the step size in position quantization is redesigned such that it doubles at each step, providing a more adaptive and scalable mapping of positions across different block sizes.

[0199] An example configuration as shown below and in Fig. 8, where each line corresponds to the log2of the block size and each entry a threshold that enables the switch to a next higher context model set is shown.

[0200] { 0, 1, 2, 3, 4, 5, 6, 7 },

[0201] { 0, 1, 2, 3, 4, 5, 6, 7 },

[0202] { 0, 1, 2, 3, 4, 5, 6, 7 },

[0203] { 0, 1, 2, 3, 4, 5, 6, 7 },

[0204] { 0, 1, 2, 3, 4, 5, 6, 8 },

[0205] { 0, 1, 2, 3, 4, 5, 8, 16 },

[0206] { 0, 1, 2, 3, 4, 8, 16, 32 },

[0207] { 0, 1, 2, 4, 8, 16, 32, 64 },

[0208] { i, 2, 4, 8, 16, 32, 64, 128 },

[0209] { 2, 4, 8, 16, 32, 64, 128, 256 },

[0210] { 4, 8, 16, 32, 64, 128, 256, 512 },

[0211] { 8, 16, 32, 64, 128, 256, 512, 1024 },

[0212] { 16, 32, 64, 128, 256, 512, 1024, 2048 },

[0213] Context Modeling with Template

[0214] Fig. 9 exemplarily depicts a schematic representation of a decoder 900 associated with coding of context modeling with template, in accordance with embodiments.

[0215] As depicted in Fig. 9, decoder 900 for block-wise decoding of a digital time-varying signal 28, 92 from a data stream 16 is configured to decode a transform 206 of a current block 140of the digital time-varying signal 28, 92 from the data stream 16 and to reconstruct 228 the current block 140using the transform 206. The decoder 900 is configured to, in decoding the transform 206 from the data stream 16, context-adaptively entropy decode 720 a significance flag 704 for coefficients 702 of the transform 206, and, for coefficients for which the significance flag indicates significance, one or more syntax elements 706 indicative of a quantization level. The decoder 900 is configured to select a context 718 for context-adaptively entropy decoding a currently decoded significance flag 708 of a current coefficient 710 by quantizing 712 a sum 714 of values derived from quantization levels or the significance flag and the one or more

[0216] FH250306PEP-2026098855. DOCX filing version PCT, rmsyntax elements of previously decoded coefficients within a template 716 placed at a position of the current coefficient 710.

[0217] That is, the decoder 900 decodes the significance flag 704 for the coefficients 702 in a context-adaptive entropy decoding manner. For example, the significance flag 704 may be an indicator indicating for indicating the significance of the coefficients 702 of the transform 206. That is, the significance flag 704 as an indicator may indicate whether the coefficients 702 are nonzero or not. For example, there may be a significance flag 704 for, or corresponding to, each coefficient in the coefficients 702 of the transform 206. In the case where the significance flag 704 indicates significance (e.g. indicative of the corresponding coefficient being non-zero), the decoder 909 is configured to decode one or more syntax elements 706 indicative of, or indicating, the quantization level of the corresponding coefficient for which the significance flag indicates significance.

[0218] The selection of the context 718 is performed, for the context-adaptive entropy decoding of the currently decoded significance flag 708 of a current coefficient 710, by quantizing 712 the sum 714 of values derived from the quantization levels of previously decoded coefficients within a template 716 placed at a position of the current coefficient 710 or values derived from the significance flag of previously decoded coefficients within a template 716 placed at a position of the current coefficient 710 and values derived from the one or more syntax elements of previously decoded coefficients within a template 716 placed at a position of the current coefficient 710. That is, the sum 714 may be formed using a combination of the values derived from the quantization levels and the one or more syntax elements, the quantization levels and the one or more syntax elements being those of previously decoded coefficients within a template 716 placed at a position of the current coefficient 710, or alternatively, the sum 714 may be formed using a combination of the values derived from the significance flags and the the one or more syntax elements, the significance flags and the one or more syntax elements being those of previously decoded coefficients within a template 716 placed at a position of the current coefficient 710.

[0219] For example, the decoder 900 may decode coefficients 218 of the transform 206 of the current block 140. The transform 206 may, for example, represent the current block in the transform domain, such as in the frequency domain.

[0220] In connection with the above described embodiments described using the depiction of Fig. 9, advantages resulting from implementations of the decoder 900 are now described. In the state-of-the-art configuration, the template T = |ci+1| + \ci+21 + |ci+3| used for context modeling FH250306PEP-2026098855. DOCX filing version PCT, rmprimarily considers the significance information of neighboring coefficients. Particularly, the context offset x is derived by x = min (2, T). However, given the statistical characteristics of biomedical signals, the context modeling with the template is modified, in the embodiments described in connection with Fig. 9, to x = min (2, (T + 1) » 1) to better reflect the nature of the data. Specifically, higher absolute levels in the preceding scanning positions are given less influence in the context modeling decision. In other words, the threshold for switching to a higher context model is increased, making the context model selection less sensitive to large preceding values. This adjustment helps avoid overestimating the probability of large coefficients in sparse signals, thereby improving entropy coding efficiency.

[0221] Implementation alternatives

[0222] Although some aspects have been described in the context of an apparatus, it is clear that these aspects also represent a description of the corresponding method, where a block or device corresponds to a method step or a feature of a method step. Analogously, aspects described in the context of a method step also represent a description of a corresponding block or item or feature of a corresponding apparatus. Some or all of the method steps may be executed by (or using) a hardware apparatus, like for example, a microprocessor, a programmable computer or an electronic circuit. In some embodiments, one or more of the most important method steps may be executed by such an apparatus.

[0223] Depending on certain implementation requirements, embodiments of the invention can be implemented in hardware or in software. The implementation can be performed using a digital storage medium, for example a floppy disk, a DVD, a Blu-Ray, a CD, a ROM, a PROM, an EPROM, an EEPROM or a FLASH memory, having electronically readable control signals stored thereon, which cooperate (or are capable of cooperating) with a programmable computer system such that the respective method is performed. Therefore, the digital storage medium may be computer readable.

[0224] Some embodiments according to the invention comprise a data carrier having electronically readable control signals, which are capable of cooperating with a programmable computer system, such that one of the methods described herein is performed.

[0225] Generally, embodiments of the present invention can be implemented as a computer program product with a program code, the program code being operative for performing one of the methods when the computer program product runs on a computer. The program code may for example be stored on a machine readable carrier.

[0226] FH250306PEP-2026098855. DOCX filing version PCT, rmOther embodiments comprise the computer program for performing one of the methods described herein, stored on a machine readable carrier.

[0227] In other words, an embodiment of the inventive method is, therefore, a computer program having a program code for performing one of the methods described herein, when the computer program runs on a computer.

[0228] A further embodiment of the inventive methods is, therefore, a data carrier (or a digital storage medium, or a computer-readable medium) comprising, recorded thereon, the computer program for performing one of the methods described herein. The data carrier, the digital storage medium or the recorded medium are typically tangible and / or non-transitionary.

[0229] A further embodiment of the inventive method is, therefore, a data stream or a sequence of signals representing the computer program for performing one of the methods described herein. The data stream or the sequence of signals may for example be configured to be transferred via a data communication connection, for example via the Internet.

[0230] A further embodiment comprises a processing means, for example a computer, or a programmable logic device, configured to or adapted to perform one of the methods described herein.

[0231] A further embodiment comprises a computer having installed thereon the computer program for performing one of the methods described herein.

[0232] A further embodiment according to the invention comprises an apparatus or a system configured to transfer (for example, electronically or optically) a computer program for performing one of the methods described herein to a receiver. The receiver may, for example, be a computer, a mobile device, a memory device or the like. The apparatus or system may, for example, comprise a file server for transferring the computer program to the receiver.

[0233] In some embodiments, a programmable logic device (for example a field programmable gate array) may be used to perform some or all of the functionalities of the methods described herein. In some embodiments, a field programmable gate array may cooperate with a microprocessor in order to perform one of the methods described herein. Generally, the methods are preferably performed by any hardware apparatus.

[0234] FH250306PEP-2026098855. DOCX filing version PCT, rmThe apparatus described herein may be implemented using a hardware apparatus, or using a computer, or using a combination of a hardware apparatus and a computer.

[0235] The apparatus described herein, or any components of the apparatus described herein, may be implemented at least partially in hardware and / or in software.

[0236] The methods described herein may be performed using a hardware apparatus, or using a computer, or using a combination of a hardware apparatus and a computer.

[0237] The methods described herein, or any components of the apparatus described herein, may be performed at least partially by hardware and / or by software.

[0238] The above described embodiments are merely illustrative for the principles of the present invention. It is understood that modifications and variations of the arrangements and the details described herein will be apparent to others skilled in the art. It is the intent, therefore, to be limited only by the scope of the impending patent claims and not by the specific details presented by way of description and explanation of the embodiments herein.

[0239] FH250306PEP-2026098855. DOCX filing version PCT, rm

Claims

Claims1. Decoder for block-wise decoding a digital time-varying signal (28; 92) from a data stream (16), configured topredict (202) a last-position pointer (214) for a current block (140) of the digital timevarying signal (28; 92) to obtain a last-position predictor (204), anddecode (208) a last-position residual (210) from the data stream (16),correct (212) the last-position predictor (204) using the last-position residual (210) to obtain a last-position pointer (214),decode (234) first coefficients (218) of a transform (206) in an interval from a first coefficient (220) of the transform (206) to a coefficient (222) of the transform (206) pointed to by the last-position pointer (214) from the data stream (16) and infer that second coefficients (224) of the transform (206) have a predefined value (226);reconstruct (228) the current block (140) using the transform (206),wherein the decoder is configured to predict (20) the last-position pointer (214) based on one or more last-position pointers (230) of further transforms (232) of previously decoded blocks (140) of the digital time-varying signal.

2. Decoder according to claim 1, wherein the second coefficients (224) of the transform (206) are in an interval from a coefficient following the coefficient (222) of the transform (206) pointed to by the last-position pointer (214) to a last coefficient of the transform (206).

3. Decoder according to claim 1 or 2, wherein the predefined value is zero.

4. Decoder according to any of claims 1 to 3, wherein the decoder is configured to predict (202) the last-position pointer (214) based on:one or more last-position pointers (230) of further transforms (232) of previously decoded blocks (140) of the digital time-varying signal in a channel of the current block (140)140140140140, and / orFH250306PEP-2026098855. DOCX filing version PCT, rmone or more last-position pointers (230) comprising, for each of one or more channels preceding the channel of the current block (140), a last-position pointer (230) of a further transform (232) of a previously decoded block (140) of the digital time-varying signal in the respective channel preceding the channel of the current block (140)140140140140.

5. Decoder according to any of claims 1 to 3, wherein the decoder is configured to predict (202) the last-position pointer (214) based on:one or more last-position pointers (230) of further transforms (232) of previously decoded blocks (140) of the digital time-varying signal in a channel of the current block (140)140140140140, and / orone or more last-position pointers (230) comprising, for each of one or more channels preceding the channel of the current block (140), a last-position pointer (230) of a further transform (232) of a previously decoded block (140) of the digital time-varying signal in the respective channel preceding the channel of the current block (140)140140140140, wherein previously decoded block (140) of the digital time-varying signal in the respective channel preceding the channel of the current block (140) represents a co-located block of the current block140140140140.

6. Decoder according to any of claims 1 to 6, wherein the decoder is configured to predict (20) the last-position pointer (214) based on one or more last-position pointers (230) of further transforms (232) of previously decoded blocks (140) of the digital time-varying signal by filtering the one or more last-position pointers (230) of the further transforms (232) of the previously decoded blocks (140) of the digital time-varying signal.

7. Decoder according to any of claims 1 to 6, wherein the decoder is configured to predict (20) the last-position pointer (214) based on one or more last-position pointers (230) of further transforms (232) of previously decoded blocks (140) of the digital time-varying signal by filtering the one or more last-position pointers (230) of the further transforms (232) of the previously decoded blocks (140) of the digital time-varying signal depending ona prediction mode for predicting the last-position pointer (214) for the current block (140) of the digital time-varying signal (28; 92), and / ora transform mode associated with the transform (206).FH250306PEP-2026098855. DOCX filing version PCT, rm8. Decoder according to any of claims 1 to 7, wherein the decoder is configured to decode (208) the last-position residual (210) from the data stream (16) using delta decoding.

9. Decoder according to any of claims 1 to 7, wherein the decoder is configured to decode (208) the last-position residual (210) from the data stream (16) delta decoded relative to last-position residuals of the on one or more last-position pointers (230) of the further transforms (232) of the previously decoded blocks (140) of the digital time-varying signal.

10. Decoder according to any of claims 1 to 9, wherein the last-position residual (210) comprises a magnitude and a sign.

11. Decoder according to any of claims 1 to 9, wherein the decoder checks, whether the data stream indicates to suppress predicting (202) the last-position pointer (214) for the current block (140) of the digital time-varying signal (28; 92) from the data stream (16) to obtain the last-position predictor (204), and if the data stream indicates to suppress predicting (202) the last-position pointer, the decoder is configured to infer that the lastposition predictor (204) is zero and to not predict (202) the last-position pointer (214) for the current block (140) of the digital time-varying signal (28; 92) from the data stream (16) to obtain the last-position predictor (204)12. Decoder according to claim 11, wherein, if the data stream indicates to suppress predicting (202) the last-position pointer, the last-position residual (210) comprises a magnitude and no sign.

13. Decoder according to any of claims 1 to 12, wherein the decoder is configured to decode (208) the last-position residual (210) from a data stream (16) using context- adaptive entropy decoding.

14. Decoder according to claim 13, wherein a context model for the context-adaptive entropy decoding depends on statistical properties of the last-position pointer.

15. Decoder according to claim 13 or 14, wherein the decoder is configured to choose a context model for the context-adaptive entropy decoding dependent on the one or more last-position pointers (230) of the further transforms (232) of the previously decoded blocks (140) of the digital time-varying signal.FH250306PEP-2026098855. DOCX filing version PCT, rm16. Decoder according to any of claims 1 to 15, wherein the decoder comprises any of the features described with regard to any of claims 22 to 31, 37 to 43, 49 to 50, 56 to 60, 66 to 67.

17. Encoder for block-wise encoding a digital time-varying signal (28; 92) into a data stream (16), configured topredict (202) a last-position pointer (214) for a current block (140) of the digital timevarying signal (28; 92) to obtain a last-position predictor (204), anddetermine a last-position residual (210) based on the last-position predictor (204) and a last-position pointer (214),encode (208) the last-position residual (210) into the data stream (16),encode (234) first coefficients (218) of a transform (206) in an interval from a first coefficient (220) of the transform (206) to a coefficient (222) of the transform (206) pointed to by the last-position pointer (214) into the data stream (16) and omit encoding second coefficients (224) of the transform (206) into the data stream;wherein the encoder is configured to predict (20) the last-position pointer (214) based on one or more last-position pointers (230) of further transforms (232) of previously encoded blocks (140) of the digital time-varying signal.

18. Method for block-wise decoding a digital time-varying signal (28; 92) from a data stream (16), comprisingpredicting (202) a last-position pointer (214) for a current block (140) of the digital timevarying signal (28; 92) from the data stream (16) to obtain a last-position predictor (204), anddecoding (208) a last-position residual (210) from the data stream (16),correcting (212) the last-position predictor (204) using the last-position residual (210) to obtain a last-position pointer (214),FH250306PEP-2026098855. DOCX filing version PCT, rmdecoding (234) first coefficients (218) of a transform (206) in an interval from a first coefficient (220) of the transform (206) to a coefficient (222) of the transform (206) pointed to by the last-position pointer (214) from the data stream (16) and inferring that second coefficients (224) of the transform (206) have a predefined value (226);reconstructing (228) the current block (140) using the transform (206),wherein the method comprises predicting (20) the last-position pointer (214) based on one or more last-position pointers (230) of further transforms (232) of previously decoded blocks (140) of the digital time-varying signal.

19. Method for block-wise encoding a digital time-varying signal (28; 92) into a data stream (16), comprisingpredicting (202) a last-position pointer (214) for a current block (140) of the digital timevarying signal (28; 92) to obtain a last-position predictor (204), anddetermining a last-position residual (210) based on the last-position predictor (204) and a last-position pointer (214),encoding (208) the last-position residual (210) into the data stream (16),encoding (234) first coefficients (218) of a transform (206) in an interval from a first coefficient (220) of the transform (206) to a coefficient (222) of the transform (206) pointed to by the last-position pointer (214) into the data stream (16) and omitting encoding second coefficients (224) of the transform (206) into the data stream;wherein the method comprises predicting (20) the last-position pointer (214) based on one or more last-position pointers (230) of further transforms (232) of previously encoded blocks (140) of the digital time-varying signal.

20. Data stream (16) generated by an encoder according to claim 17.

21. A computer program for implementing the method of claim 18 or of claim 19 when being executed on a computer or signal processor.FH250306PEP-2026098855. DOCX filing version PCT, rm22. Decoder for block-wise decoding a digital time-varying signal (28; 92) from a data stream (16), configured todecode (302) an offset value (304) for a current block (140) of the digital time-varying signal (28; 92) from the data stream (16),decode (306) a transform (206) of the current block (140) from the data stream (16)140;reconstruct (228) the current block (140) using the transform (206) in a form offset- compensated (308) using the offset value (304).

23. Decoder of claim 22, wherein the decoder is configured to read an offset present flag from the data stream,if the offset present flag indicates that the offset value (304) is present for the current block (140), the decoder is configured to decode (302) the offset value (304) for the current block (140) of the digital time-varying signal (28; 92) from the data stream (16), andif the offset present flag indicates that the offset value (304) is not present for the current block (140), the decoder is configured to infer that the offset value (304) for the current block (140) of the digital time-varying signal (28; 92) is zero.

24. Decoder of claim 23, wherein the decoder is configured to, if the offset present flag indicates that the offset value (304) is present for the current block (140), decode (302) the offset value (304) for the current block (140) of the digital time-varying signal (28; 92) from the data stream (16) using a Oth-order Exponential-Golomb code.

25. Decoder of claim 23 or 24, wherein the decoder is configured to, if the offset present flag indicates that the offset value (304) is present for the current block (140), decode (302) the offset value (304) for the current block (140) of the digital time-varying signal (28; 92) from the data stream (16) using an equiprobability mode.

26. Decoder of any of claims 23 to 25, wherein the decoder is configured to read the offset present flag from the data stream using context-adaptive entropy decoding.

27. Decoder of any of claims 22 to 26, wherein the decoder is configured to, in decoding (302) the offset value (304) for the current block (140) of the digital time-varying signalFH250306PEP-2026098855. DOCX filing version PCT, rm(28; 92) from the data stream (16), read a quantized offset value from the data stream and dequantize the quantized offset value.

28. Decoder of any of claims 22 to 27, wherein the decoder is configured to decode (306) the transform (206) of the current block (140) from the data stream (16) by decoding (234) coefficients (218) of the transform (206), andwherein the decoder is configured to add the offset value (304) to the coefficients (218) of the transform (206) after applying an inverse transformation to the transform (206) to obtain the transform (206) in a form offset-compensated (308).

29. Decoder of any of claims 22 to 27, wherein the decoder is configured to decode (306) the transform (206) of the current block (140) from the data stream (16) by decoding (234) coefficients (218) of the transform (206), andwherein the decoder is configured to apply an inverse lifting-based Discrete Cosine Transform to the transform (206) before adding the offset value (304) to obtain the transform (206) in a form offset-compensated (308).

30. Decoder of any of claims 22 to 29, wherein the offset value (304) is associated with a mean of the current block.

31. Decoder according to any of claims 22 to 30, wherein the decoder comprises any of the features described with regard to any of claims 1 to 15, 37 to 43, 49 to 50, 56 to 60, 66 to 67.

32. Encoder for block-wise encoding a digital time-varying signal (28; 92) into a data stream (16), configured toencode (302) an offset value (304) for a current block (140) of the digital time-varying signal (28; 92) into the data stream (16),encode (306) a transform (206) of the current block (140) into the data stream (16)140;wherein the current block (140) is reconstructable using the transform (206) in a form offset-compensated (308) using the offset value (304).FH250306PEP-2026098855. DOCX filing version PCT, rm33. Method for block-wise decoding a digital time-varying signal (28; 92) from a data stream (16), comprisingdecoding (302) an offset value (304) for a current block (140) of the digital time-varying signal (28; 92) from the data stream (16),decoding (306) a transform (206) of the current block (140) from the data stream (16)140;reconstructing (228) the current block (140) using the transform (206) in a form offset- compensated (308) using the offset value (304).

34. Method for block-wise encoding a digital time-varying signal (28; 92) into a data stream (16), comprisingencoding (302) an offset value (304) for a current block (140) of the digital time-varying signal (28; 92) into the data stream (16),encoding (306) a transform (206) of the current block (140) into the data stream (16)140;wherein the current block (140) is reconstructable using the transform (206) in a form offset-compensated (308) using the offset value (304).

35. Data stream (16) generated by an encoder according to one of claims 32.

36. A computer program for implementing the method of claim 33 or of claim 34 when being executed on a computer or signal processor.

37. Decoder for block-wise decoding a digital time-varying signal (28; 92) from a data stream (16), configured todecode (306) a transform (206) of a current block (140) of the digital time-varying signal (28; 92) from the data stream (16)140;reconstruct (228) the current block (140) using the transform (206), FH250306PEP-2026098855. DOCX filing version PCT, rmwherein the decoder is configured todecode (401) each of coefficients (402) of the transform (206) by decoding (404) a bin string (406) of one or more bins from the data stream (16), debinarizing (408) the bin string (406) to obtain a quantization level (410) of the respective coefficient (402) and dequantizing (412) the respective coefficient (402), andselect (414) a binarization scheme (416) out of a set (418) of predefined binarization schemes (420) for at least one of the coefficients (402) depending on one or more previously decoded coefficients (424) of the transform of the current block and / or a characteristic (422) of one or more previously decoded blocks of the digital time-varying signal (28; 92).

38. Decoder of claim 37, configured todecode a last-position pointer (214) for a current block (140) of the digital time-varying signal (28; 92) from the data stream (16),wherein the coefficients (402) of the transform (20) are positioned within an interval from a first coefficient (220) of the transform (206) to a coefficient (222) of the transform (206) pointed to by the last-position pointer (214).

39. Decoder of any of previous claims 37 or 38, wherein the predefined binarization schemes (420) comprisea first binarization scheme composed of a significance flag indicating whether coefficient significance applies followed by, in case of coefficient significance applying, a level bin string indicative of a coefficient’s absolute value, anda second binarization scheme composed of a significance flag indicating whether coefficient significance applies followed by, in case of coefficient significance applying, a parity bit indicative of a coefficient’s parity and a level bin string indicative of a remainder of the coefficient’s absolute value divided by two.

40. Decoder of any of previous claims 39, configured toFH250306PEP-2026098855. DOCX filing version PCT, rmdecode a last-position pointer (214) for a current block (140) of the digital time-varying signal (28; 92) from the data stream (16),wherein the coefficients (402) of the transform (20) are positioned within an interval from a first coefficient (220) of the transform (206) to a coefficient (222) of the transform (206) pointed to by the last-position pointer (214), andinfer that the significance flag indicates significance for the coefficient (222) of the transform (206) pointed to by the last-position pointer (214).

41. Decoder of any of previous claims 37 to 40, configured to switch from a first binarization scheme to a second binarization scheme of the predefined binarization schemes (420) for coefficients of the transform of the current block yet to be decoded upon a currently decoded coefficient whose quantization level (410) is obtained using the first binarization scheme exceeding a predetermined threshold.

42. Decoder of any of previous claims 37 to 41, configured to select among the predefined binarization schemes (420) for a current coefficient depending on a sum value derived based on one or more previously decoded coefficients of the transform of the current block or bins decoded so far for the one or more previously decoded coefficients of the transform of the current block.

43. Decoder according to any of claims 37 to 42, wherein the decoder comprises any of the features described with regard to any of claims 1 to 15, 22 to 31, 49 to 50, 56 to 60, 66 to 67.

44. Encoder for block-wise encoding a digital time-varying signal (28; 92) into a data stream (16), configured toencode (306) a transform (206) of a current block (140) of the digital time-varying signal (28; 92) into the data stream (16)140, wherein the current block (140) is reconstructable using the transform (206),wherein the encoder is configured toencode (401) each of coefficients (402) of the transform (206) by quantizing (412) the respective coefficient (402), binarizing (408) a quantization level (410) of the respectiveFH250306PEP-2026098855. DOCX filing version PCT, rmcoefficient (402) to obtain a bin string (406) and encoding (404) the bin string (406) of one or more bins into the data stream (16),select (414) a binarization scheme (416) out of a set (418) of predefined binarization schemes (420) for at least one of the coefficients (402) depending on one or more previously encoded coefficients (424) of the transform of the current block and / or a characteristic (422) of one or more previously encoded blocks of the digital time-varying signal (28; 92).

45. Method for block-wise decoding a digital time-varying signal (28; 92) from a data stream (16), comprisingdecoding (306) a transform (206) of a current block (140) of the digital time-varying signal (28; 92) from the data stream (16)140;reconstructing (228) the current block (140) using the transform (206),wherein the method comprisesdecoding (401) each of coefficients (402) of the transform (206) by decoding (404) a bin string (406) of one or more bins from the data stream (16), debinarizing (408) the bin string (406) to obtain a quantization level (410) of the respective coefficient (402) and dequantizing (412) the respective coefficient (402), andselecting (414) a binarization scheme (416) out of a set (418) of predefined binarization schemes (420) for at least one of the coefficients (402) depending on one or more previously decoded coefficients (424) of the transform of the current block and / or a characteristic (422) of one or more previously decoded blocks of the digital time-varying signal (28; 92).

46. Method for block-wise encoding a digital time-varying signal (28; 92) into a data stream (16), comprisingencoding (306) a transform (206) of a current block (140) of the digital time-varying signal (28; 92) into the data stream (16)140, wherein the current block (140) is reconstructable using the transform (206),wherein the method comprisesFH250306PEP-2026098855. DOCX filing version PCT, rmencoding (401) each of coefficients (402) of the transform (206) by quantizing (412) the respective coefficient (402), binarizing (408) a quantization level (410) of the respective coefficient (402) to obtain a bin string (406) and encoding (404) the bin string (406) of one or more bins into the data stream (16),selecting (414) a binarization scheme (416) out of a set (418) of predefined binarization schemes (420) for at least one of the coefficients (402) depending on one or more previously encoded coefficients (424) of the transform of the current block and / or a characteristic (422) of one or more previously encoded blocks of the digital time-varying signal (28; 92).

47. Data stream (16) generated by an encoder according to one of claims 44.

48. A computer program for implementing the method of claim 45 or of claim 46 when being executed on a computer or signal processor.

49. Decoder for block-wise decoding a digital time-varying signal (28; 92) from a data stream (16), configured todecode (306) a transform (206) of a current block (140) of the digital time-varying signal (28; 92) from the data stream (16)140;reconstruct (228) the current block (140) using the transform (206),wherein the decoder is configured todecode (401) each of significant coefficients (502) of the transform (20) by decoding (504) a number n of greater-than bins gtj with 0<i<n+1, indicating whether an absolute quantization level of the respective significant coefficient (502) is greater than i, anddetermine n for at least one of the significant coefficients (502) depending on one or more previously decoded coefficients (524) of the transform of the current block and / or a characteristic (522) of one or more previously decoded blocks of the digital timevarying signal (28; 92).

50. Decoder according to claim 49, wherein the decoder comprises any of the features described with regard to any of claims 1 to 15, 22 to 31, 37 to 43, 56 to 60, 66 to 67. FH250306PEP-2026098855. DOCX filing version PCT, rm51. Encoder for block-wise encoding a digital time-varying signal (28; 92) into a data stream (16), configured toencode (306) a transform (206) of a current block (140) of the digital time-varying signal (28; 92) into the data stream (16)140, wherein the current block (140) is reconstructable using the transform (206),wherein the encoder is configured toencode (401) each of significant coefficients (502) of the transform (20) by encoding (504) a number n of greater-than bins gtj with 0<i<n+1, indicating whether an absolute quantization level of the respective significant coefficient (502) is greater than i, anddetermine n for at least one of the significant coefficients (502) depending on one or more previously encoded coefficients (524) of the transform of the current block and / or a characteristic (522) of one or more previously encoded blocks of the digital timevarying signal (28; 92).

52. Method for block-wise decoding a digital time-varying signal (28; 92) from a data stream (16), comprisingdecoding (306) a transform (206) of a current block (140) of the digital time-varying signal (28; 92) from the data stream (16)140;reconstructing (228) the current block (140) using the transform (206),wherein the method comprisesdecoding (401) each of significant coefficients (502) of the transform (20) by decoding (504) a number n of greater-than bins gtj with 0<i<n+1, indicating whether an absolute quantization level of the respective significant coefficient (502) is greater than i, anddetermining n for at least one of the significant coefficients (502) depending on one or more previously decoded coefficients (524) of the transform of the current block and / or a characteristic (522) of one or more previously decoded blocks of the digital timevarying signal (28; 92).FH250306PEP-2026098855. DOCX filing version PCT, rm53. Method for block-wise encoding a digital time-varying signal (28; 92) into a data stream (16), comprisingencoding (306) a transform (206) of a current block (140) of the digital time-varying signal (28; 92) into the data stream (16)140, wherein the current block (140) is reconstructable using the transform (206),wherein the method comprisesencoding (401) each of significant coefficients (502) of the transform (20) by encoding (504) a number n of greater-than bins gtj with 0<i<n+1, indicating whether an absolute quantization level of the respective significant coefficient (502) is greater than i, anddetermining n for at least one of the significant coefficients (502) depending on one or more previously encoded coefficients (524) of the transform of the current block and / or a characteristic (522) of one or more previously encoded blocks of the digital timevarying signal (28; 92).

54. Data stream (16) generated by an encoder according to one of claims 51.

55. A computer program for implementing the method of claim 52 or of claim 53 when being executed on a computer or signal processor.

56. Decoder for block-wise decoding a digital time-varying signal (28; 92) from a data stream (16), configured todecode a transform (206) of a current block (140) of the digital time-varying signal (28; 92) from the data stream (16)140;reconstruct (228) the current block (140) using the transform (206),wherein the decoder is configured to, in decoding the transform (206) from the data stream (16),context-adaptively entropy decode coefficients (602) of the transform from the data stream by selecting (606), for a currently decoded coefficient (610), a context set Cseiout of a collection (604) of m context sets Ci with 0<i,sel<m+1 and entropy decodingFH250306PEP-2026098855. DOCX filing version PCT, rm(608) the currently decoded coefficient (610) using a context selected (612) out of the selected context set Csei, andselect (606) the context set Cseiby selecting a set of m thresholds tj,swith to,s=O, tm,s=2s-1 and tj-i,s<tj,s for all i depending on a size 2sof the current block wherein s is between smin and Smax and selecting sei so that a coefficient position j of the currently decoded coefficient falls into an interval [tsei-i,s,tsei,s],wherein the thresholds tiiSare selected so that 1) tj,s-tj.i,smonotonically increases for i for all smin— S— smax and 2) there exists at least one sthres with smin^ sthres < smax and ithres With 0 — ithres fT), SO that tj_above,s_above_tj_above-1,s_above iS greater than tj above-1,s_above "tj above- 2,s_above and tj_above,s_above_tj_ above, s_above-1 IS greater than tj_above,s_above-1_ti_above,s_above-2 fOT all m+1 > i above > i thres and all smax > s above > s thres.

57. Decoder according to claim 56, wherein the decoder is configured to context-adaptively entropy decode coefficients (602) of the transform at least with respect to a significant flag of the coefficients (602).

58. Decoder according to claim 56 or 57, wherein each of context sets Ct has the same number of contexts.

59. Decoder according to any of claims 56 to 58, wherein the decoder is configured to select the context out of the selected context set Cseibased on the sum t of previously decoded coefficients in a template.

60. Decoder according to any of claims 56 to 59, wherein the decoder comprises any of the features described with regard to any of claims 1 to 15, 22 to 31, 37 to 43, 49 to 50, 66 to 67.

61. Encoder for block-wise encoding a digital time-varying signal (28; 92) into a data stream (16), configured toencode a transform (206) of a current block (140) of the digital time-varying signal (28; 92) into the data stream (16)140, wherein the current block (140) is reconstructable using the transform (206);FH250306PEP-2026098855. DOCX filing version PCT, rmwherein the encoder is configured to, in encoding the transform (206) into the data stream (16),context-adaptively entropy encode coefficients (602) of the transform into the data stream by selecting (606), for a currently decoded coefficient (610), a context set Cseiout of a collection (604) of m context sets Ci with 0<i,sel<m+1 and entropy decoding (608) the currently decoded coefficient (610) using a context selected (612) out of the selected context set Csei, andselect (606) the context set Cseiby selecting a set of m thresholds tiiSwith t0,s=0, tm,s=2s-1 and tj.i,s<tj,sfor all i depending on a size 2sof the current block wherein s is between smin and Smax and selecting sei so that a coefficient position j of the currently decoded coefficient falls into an interval [tsei-i,s,tsei,s],wherein the thresholds tj,sare selected so that 1) tj,s-tj-i,smonotonically increases for i for all Smin— s< Smax and 2) there exists at least one Sthres with smin^ Sthres < smax and ithres With 0 — ithres < Hl, SO that ti_above,s_above"ti_above-1,s_above iS greater than tj above-1,s_above "tj above- 2,s_above and ti_above,s_above"ti_ above, s_above-1 iS greater than ti_above,s_above-1"ti_above,s_above-2 fOT all m+1 > i_above > i_thres and all smax > s_above > s_thres.

62. Method for block-wise decoding a digital time-varying signal (28; 92) from a data stream (16), comprisingdecoding a transform (206) of a current block (140) of the digital time-varying signal (28; 92) from the data stream (16)140;reconstructing (228) the current block (140) using the transform (206),wherein the method comprises, in decoding the transform (206) from the data stream (16),context-adaptively entropy decoding coefficients (602) of the transform from the data stream by selecting (606), for a currently decoded coefficient (610), a context set Cseiout of a collection (604) of m context sets Ci with 0<i,sel<m+1 and entropy decoding (608) the currently decoded coefficient (610) using a context selected (612) out of the selected context set Csei, andFH250306PEP-2026098855. DOCX filing version PCT, rmselecting (606) the context set Cseiby selecting a set of m thresholds tj,swith to,s=O, tm,s=2s-1 and tj-i,s<tj,sfor all i depending on a size 2sof the current block wherein s is between smin and smax and selecting sei so that a coefficient position j of the currently decoded coefficient falls into an interval [tsei-i,s,tSei.s],wherein the thresholds tj,sare selected so that 1) tj,s-tj-i,smonotonically increases for i for all Smin^s< Smax and 2) there exists at least one Sthres with smin^ Sthres < smax and ithres With 0 — ithres < Hl, SO that tj_above,s_above-ti_above-1,s_above iS greater than tj above-1,s_above "tj above- 2,s_above and tj_above,s_above"ti_ above, s_above-1 IS greater than tj_above,s_above-1_ti_above,s_above-2 fOT all m+1 > i above > i thres and all smax > s above > s thres.

63. Method for block-wise encoding a digital time-varying signal (28; 92) into a data stream (16), comprisingencoding a transform (206) of a current block (140) of the digital time-varying signal (28; 92) into the data stream (16)140, wherein the current block (140) is reconstructable using the transform (206);wherein the method comprises, in encoding the transform (206) into the data stream (16),context-adaptively entropy encoding coefficients (602) of the transform into the data stream by selecting (606), for a currently decoded coefficient (610), a context set Cseiout of a collection (604) of m context sets Ci with 0<i,sel<m+1 and entropy decoding (608) the currently decoded coefficient (610) using a context selected (612) out of the selected context set Csei, andselecting (606) the context set Cseiby selecting a set of m thresholds tiiSwith t0,s=0, tm,s=2s-1 and ti-i,s<tijSfor all i depending on a size 2sof the current block wherein s is between smin and smax and selecting sei so that a coefficient position j of the currently decoded coefficient falls into an interval [tSei-i,s,tSei,s],wherein the thresholds tj,sare selected so that 1) tj,s-tj-i,smonotonically increases for i for all Smin— s< Smax and 2) there exists at least one Sthres with smin^ Sthres < smax and ithres With 0 — ithres < Hl, SO that tj_above,s_above-tj_above-1,s_above iS greater than tj above-1,s_above "tj above- 2,s_above and tj_above,s_above-tj_ above, s above-1 iS greater than tj_above,s_above-1-tj_above,s_above-2 fOT all m+1 > i above > i thres and all smax > s above > s thres.FH250306PEP-2026098855. DOCX filing version PCT, rm64. Data stream (16) generated by an encoder according to one of claims 61.

65. A computer program for implementing the method of claim 62 or of claim 63 when being executed on a computer or signal processor.

66. Decoder for block-wise decoding a digital time-varying signal (28; 92) from a data stream (16), configured todecode a transform (206) of a current block (140) of the digital time-varying signal (28; 92) from the data stream (16)140;reconstruct (228) the current block (140) using the transform (206),wherein the decoder is configured to, in decoding the transform (206) from the data stream (16),context-adaptively entropy decode (720) a significance flag (704) for coefficients (702) of the transform (206), and, for coefficients for which the significance flag indicates significance, one or more syntax elements (706) indicative of a quantization level, wherein the decoder is configured to select a context (718) for context-adaptively entropy decoding a currently decoded significance flag (708) of a current coefficient (710) by quantizing (712) a sum (714) of values derived from quantization levels or the significance flag and the one or more syntax elements of previously decoded coefficients within a template (716) placed at a position of the current coefficient (710).

67. Decoder according to claim 66, wherein the decoder comprises any of the features described with regard to any of claims 1 to 15, 22 to 31, 37 to 43, 49 to 50, 56 to 60.

68. Encoder for block-wise encoding a digital time-varying signal (28; 92) into a data stream (16), configured toencode a transform (206) of a current block (140) of the digital time-varying signal (28; 92) into the data stream (16)140, wherein the current block (140) is reconstructable using the transform (206);FH250306PEP-2026098855. DOCX filing version PCT, rmwherein the encoder is configured to, in encoding the transform (206) into the data stream (16),context-adaptively entropy encode (720) a significance flag (704) for coefficients (702) of the transform (206), and, for coefficients for which the significance flag indicates significance, one or more syntax elements (706) indicative of a quantization level, wherein the encoder is configured to select a context (718) for context-adaptively entropy encoding a currently encoded significance flag (708) of a current coefficient (710) by quantizing (712) a sum (714) of values derived from quantization levels or the significance flag and the one or more syntax elements of previously encoded coefficients within a template (716) placed at a position of the current coefficient (710).

69. Method for block-wise decoding a digital time-varying signal (28; 92) from a data stream (16), comprisingdecoding a transform (206) of a current block (140) of the digital time-varying signal (28; 92) from the data stream (16)140;reconstructing (228) the current block (140) using the transform (206),wherein the method comprises, in decoding the transform (206) from the data stream (16),context-adaptively entropy decoding (720) a significance flag (704) for coefficients (702) of the transform (206), and, for coefficients for which the significance flag indicates significance, one or more syntax elements (706) indicative of a quantization level, wherein the method comprises selecting a context (718) for context-adaptively entropy decoding a currently decoded significance flag (708) of a current coefficient (710) by quantizing (712) a sum (714) of values derived from quantization levels or the significance flag and the one or more syntax elements of previously decoded coefficients within a template (716) placed at a position of the current coefficient (710).

70. Method for block-wise encoding a digital time-varying signal (28; 92) into a data stream (16), comprisingFH250306PEP-2026098855. DOCX filing version PCT, rmencoding a transform (206) of a current block (140) of the digital time-varying signal (28; 92) into the data stream (16)140, wherein the current block (140) is reconstructable using the transform (206);wherein the method comprises, in encoding the transform (206) into the data stream (16),context-adaptively entropy encoding (720) a significance flag (704) for coefficients (702) of the transform (206), and, for coefficients for which the significance flag indicates significance, one or more syntax elements (706) indicative of a quantization level, wherein the method comprises selecting a context (718) for context-adaptively entropy encoding a currently encoded significance flag (708) of a current coefficient (710) by quantizing (712) a sum (714) of values derived from quantization levels or the significance flag and the one or more syntax elements of previously encoded coefficients within a template (716) placed at a position of the current coefficient (710).

71. Data stream (16) generated by an encoder according to claim 68.

72. A computer program for implementing the method of claim 69 or of claim 70 when being executed on a computer or signal processor.FH250306PEP-2026098855. DOCX filing version PCT, rm

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