tree 8ef2284aed593a6a446bb08e32f81baa2ae3ab6c
parent e47fbcab31b13549f5df45687091bea39f407e29
author Cheng Chen <chengchen@google.com> 1671756302 -0800
committer Cheng Chen <chengchen@google.com> 1675184774 +0000

Allintra: guided adaptive quantization

In this CL, we introduce a new adaptive quantization scheme.
We read an external rate distribution map and use it to determine
quantizers for each superblock.

These following steps apply:
(1). Read rate distribution from file
(2). Estimate rate cost for each 16x16 block in preprocess stage
(3). Determine quantizer for each super block based on the relation
between two rate distributions.

This mode requires --deltaq-mode=3, since it makes use of its
information in the preprocess stage to determine quantizer.

We add two command line options (need both):
(1). --enable-rate-guide-deltaq=1. It turns on the new feature.
(2). --rate-distortion-info=input. It reads the rate distribution
from the input file.

This new scheme aims to improve perceptual quality. The quality of
the rate distribution map guides the adaptive quantization.

The perceptual quality of the final encoded image could be substantially
improved if the input rate distrbution map is well designed.

Change-Id: I44c424ba5221daa568dd072d16b3eb14adf2704b