PyAV cannot find ALSA container on Debian 11

Created by: W3AXL

Overview

When attempting to use PyAV and an ASLA input device on Debian 11, PyAV claims there is no input container named alsa despite my ffmpeg installation being able to capture from the ALSA device without any issues.

Expected behavior

>>> import av
>>> container = av.open('mic1',format='alsa')
(container opens successfully)

Actual behavior

>>> import av
>>> container = av.open('mic1',format='alsa')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "av/container/core.pyx", line 355, in av.container.core.open
  File "av/container/core.pyx", line 132, in av.container.core.Container.__cinit__
  File "av/format.pyx", line 90, in av.format.ContainerFormat.__cinit__
ValueError: no container format 'alsa'

Investigation

My FFMPEG installation appears to handle the ALSA device just fine, so I'm not sure why PyAV doesn't recognize ALSA as a valid container.

Below is the console log for a successful FFPMEG recording of the audio from the mic1 device:

$ ffmpeg -f alsa -i 'mic1' output.wav
ffmpeg version 4.3.3-0+deb11u1 Copyright (c) 2000-2021 the FFmpeg developers
  built with gcc 10 (Debian 10.2.1-6)
  configuration: --prefix=/usr --extra-version=0+deb11u1 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --arch=amd64 --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --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-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-pocketsphinx --enable-libmfx --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --enable-shared
  libavutil      56. 51.100 / 56. 51.100
  libavcodec     58. 91.100 / 58. 91.100
  libavformat    58. 45.100 / 58. 45.100
  libavdevice    58. 10.100 / 58. 10.100
  libavfilter     7. 85.100 /  7. 85.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  7.100 /  5.  7.100
  libswresample   3.  7.100 /  3.  7.100
  libpostproc    55.  7.100 / 55.  7.100
Guessed Channel Layout for Input Stream #0.0 : stereo
Input #0, alsa, from 'mic1':
  Duration: N/A, start: 1648350240.490388, bitrate: 1536 kb/s
    Stream #0:0: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (pcm_s16le (native) -> pcm_s16le (native))
Press [q] to stop, [?] for help
Output #0, wav, to 'output.wav':
  Metadata:
    ISFT            : Lavf58.45.100
    Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz, stereo, s16, 1536 kb/s
    Metadata:
      encoder         : Lavc58.91.100 pcm_s16le
size=     372kB time=00:00:02.02 bitrate=1509.2kbits/s speed=0.996x
video:0kB audio:372kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.020458%
Exiting normally, received signal 2.

Reproduction

Attempt to run av.open('<device',format='alsa')

Versions

OS: Debian 11 x64
PyAV runtime:

PyAV v8.0.3
git origin: git@github.com:PyAV-Org/PyAV
git commit: v8.0.3
library configuration: --disable-doc --disable-static --enable-fontconfig --enable-gmp --enable-gnutls --enable-gpl --enable-libaom --enable-libass --enable-libbluray --enable-libdav1d --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libwavpack --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-shared --enable-version3 --enable-zlib --prefix=/tmp/vendor
library license: GPL version 3 or later
libavcodec     58. 91.100
libavdevice    58. 10.100
libavfilter     7. 85.100
libavformat    58. 45.100
libavutil      56. 51.100
libswresample   3.  7.100
libswscale      5.  7.100

PyAV build: N/A (installed via PIP)
FFmpeg: see above console output