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

[Paul B Mahol]

On Sat, Jun 11, 2022 at 1:37 AM Аскар Сафин <safinaskar at gmail.com> wrote:

> Hi. I use Debian Linux. I always capture my screen. I do this using my
> own program, which takes rgb24 frames from X server and saves them
> lossless in my own format. At fps 4
> (but duplicate frames are dropped). My codec is absolutely trivial
> (and lossless), it is based on ideas from QOI (
> https://github.com/phoboslab/qoi ) and QOV (
> https://github.com/wide-video/qov ).
> First I apply something like QOV encoding (with interframe coding) and
> then compress every frame using zstd with level 8. Surprisingly such
> trivial codec performs very well on my data.
> It gives better compress ratio than all lossless ffmpeg codecs I tried
> (x264, x265, vp9, av1, ffv1, ffvhuff, flv).
>
> I write this not because I want to brag. I write this because it is
> possible that you will be interested in my ideas, that you will
> incorporate my ideas into your code.
>
> 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.
>
> Now let me show you some data. I have a test video named
> "test-video-2022-05-16-17.mkv" in lossless x264 fullhd, which was
> captured from my screen. Uncompressed PAM size is
> 208,268,339,335 bytes (208.2 G). Unfortunately I cannot share it,
> because it contains a lot of my personal info. Now let me show you how
> different codecs perform on this file. All data
> was collected with this premises: pix_fmt is rgb24, everything is
> lossless, gop is 32, everything is on aws ec2 c3.4xlarge with 16
> cores, everything on Debian sid with sid's version of ffmpeg.
>
> Codec: x264
> Command line: ffmpeg -loglevel warning -i /tmp/t.mkv -pix_fmt rgb24
> -c:v libx264rgb -preset veryslow -qp 0 -threads 16 -g 32 /tmp/out.mkv
> Size: 2506211845 (~ 2.5 G)
> Time: 1218.22
>
> Codec: ffv1
> Command line: ffmpeg -loglevel warning -i /tmp/t.mkv -c:v ffv1
> -pix_fmt rgb24 -level 3 -threads 16 -g 32 -context 1 -slices 4 -coder
> -2 /tmp/o.mkv
> Size: 9431473324 (~9.4 G)
> Time: 1125.15
>
> Codec: my codec (single threaded!)
> Command line: ffmpeg -loglevel warning -i /tmp/t.mkv -c:v pam -pix_fmt
> rgb24 -f image2pipe pipe: < /dev/null | /tmp/nrdy encode 8 32
> Size: 1860479127 (~1.8 G)
> Time: 470.88
>
> So, as you can see my codec beats ffv1 and x264 both by compress ratio
> and speed. Moreover, my single-threaded codec beats other
> multi-threads codecs by time. Are you interested?
> If yes, I can share my code. Of course, under some permissive license.
> Again: there is no any magic here, just something like QOV + zstd.
> Also, I can specially extract some sample
> from my videos, which doesn't contain personal info, and perform tests
> on this sample and publish sample
>

What about different samples? Not just single big one.


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