Rate-controlled requantization transcodingfor H.264/AVC video streams

摘要

Nowadays, most video material is coded using a non-scalable format. When transmitting these single-layer videobitstreams, there may be a problem for connection links with limited capacity. In order to solve this problem,requantization transcoding is often used. The requantization transcoder applies coarser quantization in orderto reduce the amount of residual information in the compressed video bitstream. In this paper, we extend arequantization transcoder for H.264/AVC video bitstreams with a rate-control algorithm. A simple algorithm isproposed which limits the computational complexity. The bit allocation is based on the bit distribution in theoriginal video bitstream. Using the bit budget and a linear model between rate and quantizer, the new quantizeris calculated. The target bit rate is attained with an average deviation lower than 6%, while the rate-distortionperformance shows small improvements over transcoding without rate control.