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Accumulated low density parity check (LDPCA) codec is proposed for DISCOVER project in distributed video coding (DVC),which offers flexible coding rate.Although it can use feedback channel to adapt the rate to the correlation of the video,but in real applications,using feedback channel can not always be possible.To solve this problem,some researchers proposed estimating the code rate at the encoder but the performance was not very good.Based on their researches,this paper considers the impact of convergence rate for iteration on rate estimate,which can be calculated using its check matrix.As a pilot study,this paper pays attention to the regular LDPCA codec.At the same time,it considers the impact of deviation in the estimated crossover probability,which gives some constraints to rate estimate.In the experiment,the proposed algorithm can improve the rate-distortion performance by up to 1 dB-1.2 dB.
Accumulated low density parity check (LDPCA) codec is proposed for DISCOVER project in distributed video coding (DVC), which offers flexible coding rate. Although it can use feedback channel to adapt the rate to the correlation of the video, but in real applications, using feedback channel can not always be possible.To solve this problem, some researchers proposed estimating the code rate at the encoder but the performance was not very good.Based on their researches, this paper considers the impact of convergence rate for iteration on rate estimate , which can be calculated using its check matrix. As a pilot study, this paper pays attention to the regular LDPCA codec. At the same time, it considers the impact of deviation in the estimated crossover probability, which gives some constraints to rate estimate. In the experiment, the proposed algorithm can improve the rate-distortion performance by up to 1 dB-1.2 dB.