80 results about "Variable bitrate" patented technology

A method of generating a parity-check matrix of a low density parity-check (LDPC) code with a variable information length and a variable code rate, an encoding/decoding method, and an apparatus using the same are provided. The method of generating a parity-check matrix of an LDPC code includes: a first parity-check matrix generation process of generating a first parity-check matrix constructed with a first information block and a parity block; and an m-th parity-check matrix generation process of generating an m-th parity-check matrix by an m-th information block to a generated (m−1)-th parity-check matrix (1<m≦M, where M is a natural number equal to or greater than two). Accordingly, it is possible to provide an LDPC code with a variable information length and a variable code rate which has a low complexity for encoding/decoding and a high quality of correction and detection of errors.

The invention relates to a network bandwidth-adaptive video stream transmission control method. In the method, a transmitter is provided with a video data buffer and a data transmission buffer, a video data input thread and a video data transmission thread which are concurrently run are set at the same time, and three main control methods for video frame loss, video code rate up-regulation and video code rate down-regulation in a video transmission process are established according to variations of a network bandwidth; a frame address array is set in the control method to realize the by-the-frame transmission and discarding of video data to avoid the occurrence of 'broken video frames' in the transmission process; and a weight accumulation method in which time is taken as a parameter is adopted by the control method to judge the variation trend of video data accumulation to ensure the regulation accuracy of a video code rate. By the method, the video code rate can be ensured to be adaptively regulated along the fluctuations of the network bandwidth or along variations of video scenes under a variable code rate; and the method can be effectively applied to real-time video monitoring in dynamic bandwidth network environments.

A control channel element detection method and apparatus is provided for detecting the Control Channel Elements (CCEs) carrying control information for a mobile station using a Channel Quality Indicator (CQI). A CCE detection method includes searching a current subframe for CCEs, and locating the CCEs carrying control information for the mobile station by decoding the current subframe with variable code rates. Searching for the CCEs includes searching the current subframe for the CCEs carrying the control information for the mobile station while changing a size type of the CCEs according to a result of a comparison between a CQI of the current subframe and a CQI of a previous subframe.

Iterative metric updating when decoding LDPC (Low Density Parity Check) coded signals and LDPC coded modulation signals. A novel approach is presented for updating the bit metrics employed when performing iterative decoding of LDPC coded signals. This bit metric updating is also applicable to decoding of signals that have been generated using combined LDPC coding and modulation encoding to generate LDPC coded modulation signals. In addition, the bit metric updating is also extendible to decoding of LDPC variable code rate and/or variable modulation signals whose code rate and/or modulation may vary as frequently as on a symbol by symbol basis. By ensuring that the bit metrics are updated during the various iterations of the iterative decoding processing, a higher performance can be achieved than when the bit metrics remain as fixed values during the iterative decoding processing.

The present invention provides a technique for supporting variable bitrate services in an OFDM environment while minimizing the impact of the variations of fading channels and interference. In general, a basic access channel (BACH) is defined by a set number of sub-carriers over multiple OFDM symbols. While the number of sub-carriers remains fixed for the BACH, the sub-carriers for any given BACH will hop from one symbol to another. Thus, the BACH is defined by a hopping pattern for a select number of sub-carriers over a sequence of symbols.

The present invention discloses a coder of LDPC code used in hierarchical quasi-cyclic expansion structure, comprising an input cache, a first depositing and caching pipeline grade, a second depositing pipeline grade, a third caching pipeline grade, a fourth depositing and caching pipeline grade and an output grade. By utilizing the character that the check matrix H is formed by connecting the quasi-cyclic sift matrix, the present invention simplifies the pipeline structure of the RU coding method, reduces the grades of the pipeline from sixth grade to fourth grade, and shortens the coding delay. Besides, the present invention decreases the largest pipeline delay and increases the coding thuoughput according to the fulfilling character of the main functional module. And the present invention also reduces the energy consumption of the coder ROM according to the operational character of the quasi-cyclic sift matrix; replaces the sparse matrixmultiply vector in the RU method with the quasi-cyclic sift unit matrix multiply vector; and replaces the non sparse matrix multiply vector in the RU method with the quasi-cyclic sift matrix multiply vector. A larger storing space can be remained in the ping pong RAM amid the grades to fit the demand of the variable length code and the VBR.

The present invention relates to a H.264 interested region coding method, specifically to a method of using code rate to control the coding of interested region, including coding methods at three levels of group-level, image-level and basic unit-level. The invention has advantages of using code rate control algorithm to performing the coding of interested region without adding extra information in the code stream, without limitation to the number and shapes of the interested region, and without adding the complexity of coding algorithm. The invention is a more flexible interested region coding method, which can be applied in all Profile of H.264, and has important application value in video monitoring, and the like fields having high requirement to the integral compression ratio; experiments show that the method is an effective H.264 interested region coding method, is suitable for constant code rate control algorithm and variable code rate control algorithm.

A method and apparatus for managing both link and disk bandwidth utilization within the context of a multiple subscriber or user information distribution system by selectively providing variable bitrate and constant low bitrate information streams to one or more subscribers.

A novel method and apparatus for efficiently coding and decoding data in a data transmission system is described. A concatenated coding scheme is presented that is easily implemented, and that provides acceptable coding performance characteristics for use in data transmission systems. The inventive concatenated channel coding technique is well suited for small or variable size packet data transmission systems. The technique may also be adapted for use in a continuous mode data transmission system. The method and apparatus reduces the complexity, cost, size and power consumption typically associated with the prior art channel coding methods and apparatuses, while still achieving acceptable coding performance. The present invention advantageously performs concatenated channel coding without the necessity of a symbol interleaver. In addition, the present invention is simple to implement and thereby consumes much less space and power that do the prior art approaches. The present invention not only eliminates the need for a symbol interleaver between the outer and inner codes, but it also enjoys a drastically reduced implementation complexity of the inner code Viterbi decoder. The preferred embodiment of the present invention comprises an inner code having short length block codes derived from short constraint length convolutional codes utilizing trellis tailbiting and a decoder comprising four four-state Viterbi decoders having a short corresponding maximum length. The inner code preferably comprises short block codes derived from four-state (i.e., constraint length 3), nonsystematic, punctured and unpunctured convolutional code. One significant advantage of the preferred embodiment of the present concatenated coding technique is that packet data transmission systems can be designed to have variable coding gains and coding rates.

An audio producing device includes a receiver for wirelessly receiving a digital audio signal from an audio source device. The audio source device may transmit the digital audio signal at a variable bitrate. A logic device determines whether the bitrate at which the audio signal is received is below a predetermined threshold. A first indicator provides an indication to a user of the system when the bitrate is below the threshold. An electro-acoustic transducer utilizes information in the digital audio signal to produce audio out loud.

A method is provided for tagging a quality metric in adaptive bitrate (ABR) streaming, which allows a client to intelligently select a variant bitrate stream using the tagged quality metric. The method includes encoding multiple streams of video data at variant bitrates, each bitrate stream having a plurality of chunks, computing a quality metric for each chunk of each stream, and tagging the quality metric with each chunk of each stream.

The invention provides an efficient superspeed effective load data transmission system for a remote sensing satellite. The efficient superspeed effective load data transmission system comprises a variable bit rate coding module, a data modulation multiplexing module, a microwave signal transmitting module and a system control module; the system control module calculates an encoding rate of a low-density parity-check code, a modulation order of amplitude phase shift keying and a turntable angle of a bearing antenna according to the relative positions of a satellite and a ground station; the variable bit rate coding module finishes channel coding of effective load data, and constitutes a data transmission frame; the data modulation multiplexing module realizes amplitude phase shift keying modulation of the data transmission frame, and performs orthogonal frequency division multiplexing on a transmission code element signal on a plurality of sub channels, after that, the transmission code element signal becomes a data modulated carrier signal; and the microwave signal transmitting module converts the data modulated carrier signal into a data modulated radio frequency signal through frequency spectrum shifting, outputs a space electromagnetic wave of a certain power, and keeps an antennae beam to automatically track the ground station; and therefore, a transmission bit rate of a Gbps magnitude can be realized.

A method and apparatus for generating a low density parity check (LDPC) code having a variable code rate, the method of generating the LDPC code having a variable code rate including: generating a first parity check matrix by combining a parity matrix or a parity check matrix and a first information word matrix; and generating a second parity check matrix by combining the first parity check matrix and a second information word matrix. According to the method and apparatus, error correction performance is enhanced.

A method for controlling the bit-rate of a bitstream of encoded video signals at a variable bitrate, the bitstream being generated by compressing a video sequence of moving pictures, wherein each picture comprises a plurality of macroblocks of pixels compressed by any of transform coding, temporal prediction, bi-dimensional motion compensated interpolation or combinations thereof, to produce any of I and/or P and/or B frames, the method involving quantization of said macroblocks effected as a function of a quantization parameter. The method includes defining a target bit-rate as well as maximum positive and negative error values between the target bit-rate and an average value of the current bit-rate of the bitstream, controlling the current bit-rate in order to constrain it between said maximum positive and negative error values, and defining an allowed range of variation for updating at least one reference parameter representative of the average value of the quantization parameter over each picture, wherein said allowed range is determined as a function of the target bit-rate and the maximum positive and negative error values.

The invention relates to a multi-channel video unicode rate control method, which comprises the following steps: collecting code statistics information, allocating multi-channel bit, allocating single-channel variable code rate bit, and calculating quantization parameter. The method not only can allocate bit to each channel according to the complexity of the video source image content, ensure that the final multiplexing bit stream of each channel, satisfy the requirement of the band width, reduce the difference of the video quality of each channel, and can ensure the stability of the mage quality inside the channel since each channel by adopting the variable code rate technology. In addition, the method is completely based on the feedback way, the analysis of the image complexity is basedon the statistics information produced during the coding process, so an additional image complexity analysis module is not required, and the cost can be reduced.

The invention discloses a direct broadcast satellite variable coding modulation and self-adaptive coding modulation hybrid working method, which comprises: a step A, in which a front-end system changes the modulation mode and code rate of a frame of data dynamically during program transmission according to program content transmission needs and thus a variable code rate modulation working mode is realized; and a step B, in which the front-end system, in the variable code rate modulation working mode, changes the variable code rate modulation working mode into a self-adaptive coding modulation working mode when acquiring the current system signal-to-noise ratio of a user. In the invention, based on the real-time variable characteristic of a transmission frame structure in a direct broadcast satellite system and the combination of the respective advantages of both the variable code rate modulation working mode and the self-adaptive coding modulation working mode, the utilization of satellite frequency resources is further optimized, the coverage requirements of the satellite broadcast systems are detailed, and the transmission effectiveness of the direct broadcast satellite system is improved.

The embodiment of the invention provides a generalized frequency division multiplexing system, an optical fiber signal generation method and an optical fiber signal generation device. The method comprises the following steps: acquiring an original signal sent by a signal source; performing probability shaping processing on the original signal, and determining an output sequence; layering the output sequence to obtain a plurality of layered output sequences; carrying out lDPC coding processing on each layered output sequence to obtain an information sequence corresponding to each layered outputsequence; and mapping the information sequence corresponding to each layered output sequence to a constellation diagram according to a preset probability distribution rule to obtain an optical fibersignal of the GFDM system. By applying the technical scheme provided by the embodiment of the invention, the GFDM system optical fiber signal can be obtained through probability forming and a variablecode rate LDPC coding technology, the energy loss of signal transmission is reduced, the coding efficiency is improved, and the error code performance and the channel capacity are improved.