274 results about "Transform coding" patented technology

Apparatus is described for digitally encoding an input audio signal for storage or transmission. A distinguishing parameter is measure from the input signal. It is determined from the measured distinguishing parameter whether the input signal contains an audio signal of a first type or a second type. First and second coders are provided for digitally encoding the input signal using first and second coding methods respectively and a switching arrangement directs, at any particular time, the generation of an output signal by encoding the input signal using either the first or second coders according to whether the input signal contains an audio signal of the first type or the second type at that time. A method for adaptively switching between transform audio coder and CELP coder, is presented. In a preferred embodiment, the method makes use of the superior performance of CELP coders for speech signal coding, while enjoying the benefits of transform coder for other audio signals. The combined coder is designed to handle both speech and music and achieve an improved quality.

The present invention describes a novel methodology for adjusting a bandwidth extension algorithm by adapting one or more of enhancing perception parameters (e.g., a signal level, a signal energy and/or a gain) of a high-band encoded signal based on the characteristics of the input signal and an encoding performance in a low band with a codec utilizing audio-band-split coding by separate encoders and decoders for each audio band. The adaptation is based on the low-band coding algorithm. It can be at least two types of such an algorithm: e.g., an algebraic code excitation linear prediction (ACELP) algorithm for a speech-like input signal and a transform algorithm of a non-speech-like input signal, such that when the ACELP coding is selected, the corresponding enhancing perception parameter is gradually tuned down and when the encoding algorithm is changed to the transform coding, the corresponding enhancing perception parameter is gradually tuned up.

Methods for fast generating spatially reduced-size images directly from compressed video streams supporting the coding of interlaced frames through transform coding and motion compensation. A sequence of reduced-size images are rapidly generated from compressed video streams by efficiently combining the steps of inverse transform, down-sampling and construction of each field image. The construction of reduced-size field images also allows the efficient motion compensation. The fast generation of reduced-size images is applicable to a variety of low-cost applications such as video browsing, video summary, fast thumbnail playback and video indexing.

A method and apparatus encode and decode video by determining whether to use discrete cosine transform (DCT) and DST for each of the horizontal and vertical transforms. During encoding, an intra-prediction is performed based on an intra-prediction mode determined for an M×N input image block to obtain an M×N intra-prediction residue matrix (E). Based on the intra-prediction mode, each of a horizontal transform and a vertical transform is performed using one of DCT and DST according to the intra-prediction mode. During decoding, the intra-prediction mode is determined from an incoming video bitstream. The M×N transformed coefficient matrix of the error residue is obtained from the video bitstream using an inverse quantizer. Based on the intra prediction mode, one of DCT and DST is performed for each of an inverse vertical transform and an inverse horizontal transform.

A method for embedding an entire image, audio or video watermark sequence within another image, audio or video data sequence with minimum loss of data quality is presented. The method exploits the de-correlation property of data coefficients in the orthogonal transform domain, similar to the application in data compression through transform coding. The present invention describes the usage of a Discrete Cosine Transform as the embedding domain. However, other orthogonal transforms such as Fourier, Walsh-Hadamard, Haar, Sine and Wavelet can also be used for this operation. A unique key derived adaptively from spatial locations registering the thresholds of the ac transform energies is used to unlock or de-watermark the embedded image or audio sequence. Moreover, an exponential filter has been developed to compress and expand the watermark coefficients prior to the embedding and retrieval process. The method can be used in resolving multimedia copyright protection issues arising on the Internet and in the music industry, such as the inclusion of a company's logo or an artist's recorded voice. The method can also be incorporated as a built-in feature for digital recording devices, such as still and video cameras, as well as more recent devices such as VCD and DVD players. Moreover, the method can be applied to the commercial and service sectors, where security in transmission and reception of private information in terms of speech or image is of the utmost importance.

A system for creating composite encoded video from two or more encoded video sources in the encoded domain. In response to user input, a markup language-based graphical layout is retrieved. The graphical layout includes frame locations within a composite frame for at least a first encoded source and a second encoded source. The system either retrieves or receives the first and second encoded sources. The sources include block-based transform encoded data. The system also includes a stitcher module for stitching together the first encoded source and the second encoded source according to the frame locations of the graphical layout to form an encoded frame. The system outputs an encoded video stream that is transmitted to a client device associated with the user. In response to further user input, the system updates the state of an object model and replaces all or a portion of one or more frames of the encoded video stream. The system may be used with MPEG encoded video.

A variable block transform system, medium, and a system, medium, and method for video encoding/decoding using the variable block transform. The system includes a transform block size determination unit that determines the transform block size for components of an input video based on a format, defining the components, of the input video or characteristics of the components, and a transform coding unit that performs transform coding on each of the color components of the input video according to the determined transform block sizes and outputs transform coefficients.

In an embodiment, bitstream elements of sub-frames are encoded differentially to a global gain value so that a change of the global gain value results in an adjustment of an output level of the decoded representation of the audio content. Concurrently, the differential coding saves bits. Even further, the differential coding enables the lowering of the burden of globally adjusting the gain of an encoded bitstream. In another embodiment, a global gain control across CELP coded frames and transform coded frames is achieved by co-controlling the gain of the codebook excitation of the CELP codec, along with a level of the transform or inverse transform of the transform coded frames. In another embodiment, the gain value determination in CELP coding is performed in the weighted domain of the excitation signal.

A single-shot spectral imager or imaging system which acquires multiplexed spatial and spectral data in a single snapshot with high optical collection efficiency and with the speed limited only by the readout time of the detector circuitry. The imager uses dispersive optics together with spatial light modulators to encode a mathematical transform onto the acquired spatial-spectral data. A multitude of encoded images is recorded simultaneously on a focal plane array and subsequently decoded to produce a spectral/spatial hypercube.

A method and apparatus is disclosed herein for using an in-the-loop denoising filter for quantization noise removal for video compression. In one embodiment, the video encoder comprises a transform coder to apply a transform to a residual frame representing a difference between a current frame and a first prediction, the transform coder outputting a coded differential frame as an output of the video encoder; a transform decoder to generate a reconstructed residual frame in response to the coded differential frame; a first adder to create a reconstructed frame by adding the reconstructed residual frame to the first prediction; a non-linear denoising filter to filter the reconstructed frame by deriving expectations and performing denoising operations based on the expectations; and a prediction module to generate predictions, including the first prediction, based on previously decoded frames.

In a transform encoder for audio data, encoded data in the form of mantissas, exponents and coupling data is packed into fixed length frames in an output bitstream. The fields within the frame for carrying the different forms of data are variable in length, and apace within the frame must be allocated between them to fit all of the required information into the frame. The space required by the various data types depends on certain encoding parameters, which are calculated for a particular frame before the data is encoded, thus ensuring that the encoded data will fit into the frame before the computationally expensive encoding process is carried out. Information in relation to, for example, transform length, coupling parameters and exponent strategy are determined, which allows the space required for the coupling and exponent data to be calculated. The mantissa encoding parameters can then be iteratively determined so that the encoded mantissas will fit into the frame with the other encoded data. The determined encoding parameters are stored and the audio data is encoded according to those parameters after it has been determined that the encoded data will fit into the frame.

The embodiments of the present invention provide a method and a device for encoding and decoding videos, and relate to the communication field, and an efficient transformation matrix corresponding to features of each residual block is selected for transformation, which therefore improves encoding efficiency. The solution provided in an embodiment of the present invention is: generating a prediction residual according to input video data; selecting a set of best transformation matrixes among multiple candidate transformation matrixes according to an intra-frame prediction mode and rate-distortion criteria to perform transform-coding on the prediction residual and obtain a transformation result; and generating an encoded stream according to the transformation result and selected transformation matrix index information.

A transform coder adaptively configures window sizes for transform coding in a two-pass process to maximize coding efficiency, while achieving necessary time resolution to avoid pre-echo. In a first pass, the coder places small size windows over detected transient regions of an input signal in an open-loop window configuration process. In a second pass, the coder adjusts the window size configuration according to measurements of the achieved quality in a closed-loop window configuration process. Where quality measurement shows unacceptable quantization noise, the coder increases window size. Where pre-echo is detected, the coder reduces window size within coding bit rate constraints.

Methods, devices, and systems for coding and decoding audio are disclosed. At least two transforms are applied on an audio signal, each with different transform periods for better resolutions at both low and high frequencies. The transform coefficients are selected and combined such that the data rate remains similar as a single transform. The transform coefficients may be coded with a fast lattice vector quantizer. The quantizer has a high rate quantizer and a low rate quantizer. The high rate quantizer includes a scheme to truncate the lattice. The low rate quantizer includes a table based searching method. The low rate quantizer may also include a table based indexing scheme. The high rate quantizer may further include Huffman coding for the quantization indices of transform coefficients to improve the quantizing/coding efficiency.

Methods and apparatus to process multimedia data enabling efficient partial decoding of transform coded data are described. A decoder device receives transform coefficients, where the transform coefficients are associated with multimedia data. The decoder device determines a set of multimedia samples to be reconstructed. In one aspect, the set of samples to be reconstructed is a subset of a matrix of transformed multimedia samples. The decoder device determines a set of transform coefficients to be used to reconstruct the multimedia samples. In one aspect, the transform coefficients are used to scale partial basis images associated with the encoding method used to generate the transform coefficients, resulting in reconstructed multimedia samples.

The present invention provides a method for compensating transient effects in transform coding and decoding of a combined speech and audio in electronic devices by using a transform based time-frequency domain codec. The method can combine, e.g., a CELP (code excited linear prediction) type speech codec and a transform type audio codec. The invention describes a compensation method to handle the transient (e.g., from the CELP coding to the transform coding) in transform coding when the number of quantized transform coding coefficients is lower than in the output of the transform.

A processed representation of an audio signal having a sequence of frames is generated by sampling the audio signal within first and second frames of the sequence of frames, the second frame following the first frame, the sampling using information on a pitch contour of the first and second frames to derive a first sampled representation. The audio signal is sampled within the second and third frames, the third frame following the second frame in the sequence of frames. The sampling uses the information on the pitch contour of the second frame and information on a pitch contour of the third frame to derive a second sampled representation. A first scaling window is derived for the first sampled representation, and a second scaling window is derived for the second sampled representation, the scaling windows depending on the samplings applied to derive the first sampled representations or the second sampled representation.

A transform coder leading to reduction of degradation of perceptual sound quality even if an adequate number of bits is not assigned. Candidates of a correction scale factor stored in a correction scale factor codebook (123) are outputted one by one, and an error signal is generated by subjecting the candidate and scale factors outputted from scale factor computing sections (121, 122) to a predetermined operation. A judging section (126) determines a weight vector given to a weighted error computing section (127) depending on the sign of the error signal. The weighted error computing section (127) computes the square of the error signal, multiplies the square of the error signal by the weight vector given from the judging section (126), and computes a weighted squared error E. A search section (128) determines the candidates of the correction scale factor which minimizes the weighted squared error E by a closed loop processing.

The present invention relates to a method which can selectively skip a transform to alleviate problems of deterioration in compression rate and image quality which are mainly generated when applying the motion compensation-transform encoding image compression technique which is mainly used currently, to an image having a drastic spatial change in a pixel value such as a computer image, and can skip the transform by comparing a transform size of a current block and the size of a maximum transform skip block with each other, and provides an efficient signaling technique therefor. The method includes the steps of: comparing the size of a current transform unit (TU) with the size of a maximum transform skip block when determining whether to transform a residual signal corresponding to difference between the current block and a prediction block; and determining whether to perform the transform on the basis of the comparison information on the size of the TU and the size of the maximum transform skip block.

A codec supporting switching between time-domain aliasing cancellation transform coding mode and time-domain coding mode is made less liable to frame loss by adding a further syntax portion to the frames, depending on which the parser of the decoder may select between a first action of expecting the current frame to have, and thus reading forward aliasing cancellation data from the current frame and a second action of not-expecting the current frame to have, and thus not reading forward aliasing cancellation data from the current frame. In other words, while a bit of coding efficiency is lost due to the provision of the new syntax portion, it is merely the new syntax portion which provides for the ability to use the codec in case of a communication channel with frame loss. Without the new syntax portion, the decoder would not be capable of decoding any data stream portion after a loss and will crash in trying to resume parsing. Thus, in an error prone environment, the coding efficiency is prevented from vanishing by the introduction of the new syntax portion.

Methods and apparatus for coding system incorporating AMT (adaptive multiple core transform) for the chroma transform blocks (TBs) are disclosed. According to one method, one or more flags are signaled to indicate whether AMT can be applied for the chroma TBs. If the one or more flags indicate that AMT can be applied for the chroma TBs, the chroma TBs can use the same or separate AMT selection information as the corresponding Luma TB. According to another method, when AMT and the transform skip mode are both available for use for a transform block, the on/off signaling of AMT is coded before the on/off signaling of the transform skip mode. The on/off signaling of the transform skip mode is not coded if the coded AMT on/off flag is true. The on/off signaling of the transform skip mode can be inferred to be false if not coded.