Adaptation of H.264/AVC Predictions for enabling Fast Transrating

摘要

Fast video transrating algorithms for DCT-based video coding standards have proven their efficiency in many applications and are widely used in the industry. However, they cannot be re-used for H.264/AVC because they introduce an unacceptable level of drift. To settle this issue, this paper proposes to adapt the H.264/AVC predictions by separately processing the DC component from the other AC coefficients. This allows the drift to be removed from the re-quantization transrating algorithms. Experimental results show the amount of bits in our prediction scheme is only increased by 2.46 % for CIF and 1.87% for 720p in Intra in comparison with the H.264/AVC codec under the same PSNR. The performance of the fast transrating algorithms applied on streams generated with our method are improved dramatically, allowing to directly compete with the best in class, but computation load demanding Cascaded Pixel Domain decode and recode Transcoding (CPDT) architecture. Additionally, one potential application induced by this new prediction principle is the partial decoding of video streams to obtain reduced size images.