Guided Transcoding Using Deflation and Inflation
Christopher Hollmann, Rickard Sjöberg · 2018
This paper analyzes and improves an existing guided transcoding scheme called deflation and inflation. By adding three new coding tools, required storage is reduced by 4.2 percentage points on a test set defined by the Moving Picture Experts Group. The first tool predicts coefficient signs, the second tool reorders coefficients using a dynamic scanning order, and the third tool uses new contexts for the binary coder to encode whether coefficients are non-zero or not. All three tools are based on a new method for estimating the likelihood of a coefficient being non-zero. Furthermore, the paper introduces a modified test configuration using a fast transcoder based on the x265 encoder for comparisons. Using this configuration, the three proposed tools provide a storage reduction of 4.4 percentage points with a transcoding complexity of around 5% of a transcoder based on x265.