[FFmpeg-devel] Trivial codec based on QOI and zstd compresses better than all lossless ffmpeg codecs on my data from screen

[Martijn van Beurden]

Op za 11 jun. 2022 01:37 schreef Аскар Сафин <safinaskar at gmail.com>:

> ffv1 spec reads: "FFV1 is designed to support a wide range of lossless
> video applications such as... screen recording..." Unfortunately, ffv1
> turned out to be bad compared to my codec
> on screen recording data, so it is possible ffv1 could benefit from my
> ideas.
>

While the spec indeed mentions screen recording, it seems the kind of
screen recording you do is probably not a use where ffv1 shines.

The spec abstract starts with "This document defines FFV1, a lossless,
intra-frame video encoding format." Notice "intra-frame". ffv1 does not do
inter-frame decorrelation like most other codecs do. So, when compressing
data with high inter-frame correlation, ffv1 doesn't do well.

ffv1 does very well on for example film scans, when the presence of film
grain makes inter-frame decorrelation of relatively little use. In screen
captures where > 95% of the frame stays exactly the same, this approach
doesn't work well indeed.