Opened 9 months ago

#10389 new defect

av1_amf ignores most quality/bitrate settings except for b:v

Reported by: alraz Owned by:
Priority: normal Component: undetermined
Version: unspecified Keywords: av1_amf, av1, amd
Cc: Blocked By:
Blocking: Reproduced by developer: no
Analyzed by developer: no

Description

hello everyone

I'm new here. This is my first bug report, so, please bear with me if I missed anything here :)
Trying my best.

Summary of the bug:

Been trying to re-encode a bunch of existing mkv files I have that I created with OBS using H.264 VBR settings to AV1 using AMD's hardware encoder.

The encoder seems to ignore all of the following settings:

-cq 
-qp
-crf 
-qscale 
-minrate
-maxrate

No matter which combination of the above settings I use, the codec will always use a bitrate of about 2 mbps and the console will always show a "q" value of "-0.0". I tried using all the settings on their own as wall a several possible combinations of only a few of them, most of them, etc. as well as different quality values for each of them, but nothing seems to make any difference.

Example:

 ffmpeg -i "2023-05-27_17-53-42.mkv" -map 0 -c:v av1_amf -preset 0 -bufsize 192M -cq 17 -qp 17 -crf 17 -qscale 17 -minrate 15000k -maxrate 35000k -f mp4  -y "h265/2023-05-27_17-53-42.mp4"

[...]

frame=  495 fps= 54 q=-0.0 Lsize=    2480kB time=00:00:08.36 bitrate=2429.2kbits/s speed=0.919x

However, if I specify a target bitrate with "b:v", then the encoder will ignore all other settings and encode using only that target bitrate.

Example:

ffmpeg -i "2023-05-27_17-53-42.mkv" -map 0 -c:v av1_amf -b:v 15000k -preset 0 -qp 17 -minrate 15000k -maxrate 35000k -f mp4  -y "h265/2023-05-27_17-53-42.mp4"

[...]

frame=  677 fps= 65 q=-0.0 Lsize=   20876kB time=00:00:11.41 bitrate=14983.7kbits/s speed= 1.1x

More interestingly, the resulting file will be the exact same size regardless of what combination of settings I use. The only thing that seems to matter is whether or not I use "b:v".

This does not happen when I use another codec that doesn't use AMD hardware. Example:

 ffmpeg -i "2023-05-27_17-53-42.mkv" -map 0 -c:v libx264 -preset 0 -bufsize 192M -cq 17 -qp 17 -crf 17 -qscale 17 -minrate 15000k -maxrate 35000k -f mp4  -y "h265/2023-05-27_17-53-42.mp4"

[...]

frame=  401 fps= 52 q=23.0 size=   33792kB time=00:00:07.87 bitrate=35165.7kbits/s speed=1.03x

Notice that the "q" value is positive (though not exactly what I specified) and the bitrate is somewhat between the range specified.

If it helps: I noticed that the "-quality" setting DOES seem to be considered by the encoder: with higher settings, it is significantly slower and the resulting file is slightly bigger. I have not been able to evaluate if the video quality is actually any better, but I have no reason to assume it is not given the symptoms are what's expected for this setting.

My ffmpeg version:

B:\capture>ffmpeg -version
ffmpeg version N-110789-g8d662adcc9-20230527 Copyright (c) 2000-2023 the FFmpeg developers
built with gcc 12.2.0 (crosstool-NG 1.25.0.152_89671bf)
configuration: --prefix=/ffbuild/prefix --pkg-config-flags=--static --pkg-config=pkg-config --cross-prefix=x86_64-w64-mingw32- --arch=x86_64 --target-os=mingw32 --enable-gpl --enable-version3 --disable-debug --disable-w32threads --enable-pthreads --enable-iconv --enable-libxml2 --enable-zlib --enable-libfreetype --enable-libfribidi --enable-gmp --enable-lzma --enable-fontconfig --enable-libvorbis --enable-opencl --disable-libpulse --enable-libvmaf --disable-libxcb --disable-xlib --enable-amf --enable-libaom --enable-libaribb24 --enable-avisynth --enable-chromaprint --enable-libdav1d --enable-libdavs2 --disable-libfdk-aac --enable-ffnvcodec --enable-cuda-llvm --enable-frei0r --enable-libgme --enable-libkvazaar --enable-libass --enable-libbluray --enable-libjxl --enable-libmp3lame --enable-libopus --enable-librist --enable-libssh --enable-libtheora --enable-libvpx --enable-libwebp --enable-lv2 --disable-libmfx --enable-libvpl --enable-openal --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopenmpt --enable-librav1e --enable-librubberband --enable-schannel --enable-sdl2 --enable-libsoxr --enable-libsrt --enable-libsvtav1 --enable-libtwolame --enable-libuavs3d --disable-libdrm --disable-vaapi --enable-libvidstab --enable-vulkan --enable-libshaderc --enable-libplacebo --enable-libx264 --enable-libx265 --enable-libxavs2 --enable-libxvid --enable-libzimg --enable-libzvbi --extra-cflags=-DLIBTWOLAME_STATIC --extra-cxxflags= --extra-ldflags=-pthread --extra-ldexeflags= --extra-libs=-lgomp --extra-version=20230527
libavutil      58.  9.100 / 58.  9.100
libavcodec     60. 14.101 / 60. 14.101
libavformat    60.  5.100 / 60.  5.100
libavdevice    60.  2.100 / 60.  2.100
libavfilter     9.  8.101 /  9.  8.101
libswscale      7.  2.100 /  7.  2.100
libswresample   4. 11.100 /  4. 11.100
libpostproc    57.  2.100 / 57.  2.100

Patches should be submitted to the ffmpeg-devel mailing list and not this bug tracker (leaving this note here because it came as part of the template).

Change History (0)

Note: See TracTickets for help on using tickets.