[Libav-user] No such filter: 'feedback'

[James Insell]

Hi,

I've been attempting to use the 'feedback' video filter, which is 
documented here: https://ffmpeg.org/ffmpeg-filters.html#feedback

Unfortunately I get the following error message :

"[AVFilterGraph @ 0x55e551121ec0] No such filter: 'feedback'
Error initializing complex filters.
Invalid argument
pipe:: Invalid data found when processing input"

I updated my ffmpeg installation, from FFmpeg 4.4.2 "Rao", to FFmpeg 
5.0.1 "Lorentz", as I gathered from elsewhere that 'feedback' was a new 
filter, but I still got the same error message.

Is 'feedback' actually present in the 5.0.1 release?  I believe I have 
the correct libavfilter library enabled/installed.

I've found reference to the filter in patchwork.ffmpeg.org ( 
https://patchwork.ffmpeg.org/project/ffmpeg/patch/20220410230243.87094-1-onemda@gmail.com/ 
), but do I really have to go to the effort of downloading the source 
code, adding the patch, and building ffmpeg from scratch? If so, I 
suggest that the inclusion of the filter in the online documentation is 
premature, and only filters present in full ffmpeg releases should be 
listed.

Would it not at least help to have a note in the documentation of each 
filter stating the release version that the filter was available from?

The header I get from running 'ffmpeg -version' is below :

ffmpeg version 5.0.1-1+18.04.sav1 Copyright (c) 2000-2022 the FFmpeg 
developers
built with gcc 7 (Ubuntu 7.5.0-3ubuntu1~18.04)
configuration: --prefix=/usr --extra-version=1+18.04.sav1 
--toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu 
--incdir=/usr/include/x86_64-linux-gnu --arch=amd64 --enable-gpl 
--disable-stripping --enable-gnutls --enable-ladspa --enable-libaom 
--enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca 
--enable-libcdio --enable-libcodec2 --enable-libdav1d --enable-libflite 
--enable-libfontconfig --enable-libfreetype --enable-libfribidi 
--enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame 
--enable-libmysofa --enable-libopenjpeg --enable-libopenmpt 
--enable-libopus --enable-libpulse --enable-librabbitmq --enable-librist 
--enable-librubberband --enable-libshine --enable-libsnappy 
--enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh 
--enable-libtheora --enable-libtwolame --enable-libvidstab 
--enable-libvmaf --enable-libvorbis --enable-libvpx --enable-libwebp 
--enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzimg 
--enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx 
--enable-openal --enable-opencl --enable-opengl --enable-sdl2 
--enable-pocketsphinx --enable-librsvg --enable-crystalhd 
--enable-libmfx --enable-libsvtav1 --enable-libdc1394 --enable-libdrm 
--enable-libiec61883 --enable-chromaprint --enable-frei0r 
--enable-libplacebo --enable-libx264 --enable-shared
libavutil      57. 17.100 / 57. 17.100
libavcodec     59. 18.100 / 59. 18.100
libavformat    59. 16.100 / 59. 16.100
libavdevice    59.  4.100 / 59.  4.100
libavfilter     8. 24.100 /  8. 24.100
libswscale      6.  4.100 /  6.  4.100
libswresample   4.  3.100 /  4.  3.100
libpostproc    56.  3.100 / 56.  3.100

Any help much appreciated.

Thanks.

James.