FFV1 seems badly broken

[Andrew]

Summary of the bug: Trying to use FFV1 as a lossless codec for no-recoding stream-copy work, or any other purpose, seems pointless. Blues and reds are getting mulched.

How to reproduce: I've created a simple color bars diagnostic image. By doing quick encodes to four different "lossless" codecs it is very obvious that ffv1 is not working correctly.

ffmpeg -framerate 60 -loop 1 -i colorbar.png -t 10.0 -c:v ffv1 -pix_fmt yuv444p test-ffv1.mkv

ffmpeg -framerate 60 -loop 1 -i colorbar.png -t 10.0 -c:v h264 -crf 0 -pix_fmt yuv444p test-h264-lossless.mkv

ffmpeg -framerate 60 -loop 1 -i colorbar.png -t 10.0 -c:v hevc -x265-params lossless=1 -pix_fmt yuv444p test-h265-lossless.mkv

ffmpeg -framerate 60 -loop 1 -i colorbar.png -t 10.0 -c:v vp9 -lossless 1 -row-mt 1  -pix_fmt yuv444p test-vp9-lossless.mkv

ffmpeg version 2023-04-10-git-b18a9c2971-full_build-www.gyan.dev Copyright (c) 2000-2023 the FFmpeg developers
built with gcc 12.2.0 (Rev10, Built by MSYS2 project)
configuration: --enable-gpl --enable-version3 --enable-static --disable-w32threads --disable-autodetect --enable-fontconfig --enable-iconv --enable-gnutls --enable-libxml2 --enable-gmp --enable-bzlib --enable-lzma --enable-libsnappy --enable-zlib --enable-librist --enable-libsrt --enable-libssh --enable-libzmq --enable-avisynth --enable-libbluray --enable-libcaca --enable-sdl2 --enable-libaribb24 --enable-libdav1d --enable-libdavs2 --enable-libuavs3d --enable-libzvbi --enable-librav1e --enable-libsvtav1 --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs2 --enable-libxvid --enable-libaom --enable-libjxl --enable-libopenjpeg --enable-libvpx --enable-mediafoundation --enable-libass --enable-frei0r --enable-libfreetype --enable-libfribidi --enable-liblensfun --enable-libvidstab --enable-libvmaf --enable-libzimg --enable-amf --enable-cuda-llvm --enable-cuvid --enable-ffnvcodec --enable-nvdec --enable-nvenc --enable-d3d11va --enable-dxva2 --enable-libvpl --enable-libshaderc --enable-vulkan --enable-libplacebo --enable-opencl --enable-libcdio --enable-libgme --enable-libmodplug --enable-libopenmpt --enable-libopencore-amrwb --enable-libmp3lame --enable-libshine --enable-libtheora --enable-libtwolame --enable-libvo-amrwbenc --enable-libcodec2 --enable-libilbc --enable-libgsm --enable-libopencore-amrnb --enable-libopus --enable-libspeex --enable-libvorbis --enable-ladspa --enable-libbs2b --enable-libflite --enable-libmysofa --enable-librubberband --enable-libsoxr --enable-chromaprint
libavutil      58.  6.100 / 58.  6.100
libavcodec     60.  9.100 / 60.  9.100
libavformat    60.  4.101 / 60.  4.101
libavdevice    60.  2.100 / 60.  2.100
libavfilter     9.  5.100 /  9.  5.100
libswscale      7.  2.100 /  7.  2.100
libswresample   4. 11.100 /  4. 11.100
libpostproc    57.  2.100 / 57.  2.100

[Andrew]

Testing colorbar image

[Andrew]

FFV1 playback

[Andrew]

h264-lossless playback

[Andrew]

h265-lossless playback

[Andrew]

VP9-lossless playback

[Elon Musk]

Doing rgb-yuv-rgb conversion is not lossless.

Fix your colorbars image if you can.