Analysis of drift-error propagation in H.264/AVC transcoder for variable bitrate streaming system

Video transcoding is one of the most essential technologies in consumer electronics server and gateway products for a variable bitrate video streaming system. Especially, for a real-time streaming system, drift-error resilient coded bitstreams that do not require high complexity transcoding processes are desired. For the generation of drift-error resilient coded bitstreams at the encoder side, an investigation on the drift-error propagation characteristic in H.264/AVC by applying different motion compensation (MC) precisions are carried out in this paper. The results show that the drift-error propagation in half-pixel MC precision increases due to the usage of six-tap filter. For quarter-pixel MC precision, the drift-error propagation decreases. Besides that, we found out that the requantization parameter and MC precision only affects the amount of error in the requantized frame but amount of error propagation depends on the MC precision and sequence of the pixel value. It is also found that drift-error propagation ratio is defined at some point regardless of MC precisions.