Analysis of Generation Loss for Wavelet-Based Compression

This article investigates the sources of generation loss, the loss of picture quality over multiple coding generations, for waveletbased mezzanine video compression using the VC-2 video codec. The theoretical mechanisms of generation loss are presented, highlighting the detrimental interaction between quantization in the encoder and otherwise reversible processes in the decoder. A novel experimental investigation of the VC-2 video codec is presented, in which the significance of different sources of generation loss are compared and the parameters that impact the propagation of generation loss are contrasted. The most significant source of generation loss examined in this article is the addition of an 'accuracy bit shift,' which improves subjective quality for a single coding generation but causes losses over subsequent generations. Of those investigated, the most significant way to mitigate the propagation of generation loss is to decrease the wavelet transform depth. This article concludes that, through careful parameter selection and signal processing design, generation loss for wavelet-based mezzanine codecs may be practically eliminated. © 2002 Society of Motion Picture and Television Engineers, Inc.