Error accumulation in hybrid DPCM/DCT video coding

摘要

This paper studies the problem of error accumulation with the hybrid DPCM/DCT video coding. It is shown that the error accumulation results from quantization of the temporal prediction errors in the DCT domain. When the temporal prediction error for a coefficient is smaller than the quantization dead zone for a number of successive frames, error accumulates for the coefficient. This is particularly the case for the high order DCT coefficients which, in general, exhibit small amplitude and low temporal correlation. To alleviate the error accumulation, it is proposed that a loop filter be inserted in the hybrid coding loop to remove the temporal prediction for the coefficients whose temporal prediction errors contain more information than the coefficients themselves.