Torchvision Python Setup Script Does not handle FFMPEG Version Properly

🐛 Bug

When building torchvision from source with ffmpeg support (I wanted to use torchvision.io.VideoReader class which needs the torchvisoin package installed from source with ffmpeg support), it seems that the setup script does not handle the version of ffmpeg correctly. In fact, the intsalled version of ffmpeg in my case was an ubuntu revision of ffmpeg (the exact version was 4.2.4-1ubuntu0.1) and with this version the setup.py scripts crashes.

To Reproduce

Steps to reproduce the behavior:

1. Install the ffmpeg library:

sudo apt-get update
sudo apt-get install ffmpeg

1. Build the torchvision package from source with FFMpeg supoprt:

export NO_FFMPEG=false
python setup.py install

The first few lines of the output are as follows:

Building wheel torchvision-0.11.0a0+8d54022
PNG found: True
libpng version: 1.6.37
Building torchvision with PNG image support
libpng include path: /usr/include/libpng16
Running build on conda-build: False
Running build on conda: False
JPEG found: True
Building torchvision with JPEG image support
NVJPEG found: True
Building torchvision with NVJPEG image support
Error fetching ffmpeg version, ignoring ffmpeg.
FFmpeg found: False

1. Although ffmpeg is already installed, the script cannot recognize its version. After some inspection, I found that the following try-catch block in setup.py raises the exception (lines 351-362 of setup.py on the master branch):

if has_ffmpeg:
    try:
        ffmpeg_version = subprocess.run(
            'ffmpeg -version | head -n1', shell=True,
            stdout=subprocess.PIPE).stdout.decode('utf-8')
        ffmpeg_version = ffmpeg_version.split('version')[-1].split()[0]
        if StrictVersion(ffmpeg_version) >= StrictVersion('4.3'):
            print(f'ffmpeg {ffmpeg_version} not supported yet, please use ffmpeg 4.2.')
            has_ffmpeg = False
    except (IndexError, ValueError):
        print('Error fetching ffmpeg version, ignoring ffmpeg.')
        has_ffmpeg = False

1. This block simply tries to extract the ffmpeg version by running the ffmpeg -version command. When I run this command in my shell environment I get the following output:

ffmpeg version 4.2.4-1ubuntu0.1 Copyright (c) 2000-2020 the FFmpeg developers
built with gcc 9 (Ubuntu 9.3.0-10ubuntu2)
configuration: --prefix=/usr --extra-version=1ubuntu0.1 --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-avisynth --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --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-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --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-libdc1394 --enable-libdrm --enable-libiec61883 --enable-nvenc --enable-chromaprint --enable-frei0r --enable-libx264 --enable-shared
libavutil      56. 31.100 / 56. 31.100
libavcodec     58. 54.100 / 58. 54.100
libavformat    58. 29.100 / 58. 29.100
libavdevice    58.  8.100 / 58.  8.100
libavfilter     7. 57.100 /  7. 57.100
libavresample   4.  0.  0 /  4.  0.  0
libswscale      5.  5.100 /  5.  5.100
libswresample   3.  5.100 /  3.  5.100
libpostproc    55.  5.100 / 55.  5.100

With this output from the version command, it is easy to check that the ffmpeg_version variable in the try-catch block becomes “4.2.4-1ubuntu0.1”. Therefore, StrictVersion does not recognize this string as a valid input and raises a ValueError exception.

Expected behavior

When I removed the try-catch block from setup script, torchvision was built successfully and I could use the io.VideoReader class without any problems. Regarding the installed version of ffmpeg, the only restriction that I saw was that versions 4.3 and higher are not supported. Nothing was mentioned about the ubuntu revision package which was installed on my machine as the default.

Environment

Please copy and paste the output from our environment collection script (or fill out the checklist below manually).

You can get the script and run it with:

wget https://raw.githubusercontent.com/pytorch/pytorch/master/torch/utils/collect_env.py
# For security purposes, please check the contents of collect_env.py before running it.
python collect_env.py

PyTorch version: 1.9.0+cu111 Is debug build: False CUDA used to build PyTorch: 11.1 ROCM used to build PyTorch: N/A

OS: Ubuntu 20.04.2 LTS (x86_64) GCC version: (Ubuntu 9.3.0-17ubuntu1~20.04) 9.3.0 Clang version: 10.0.0-4ubuntu1 CMake version: version 3.16.3 Libc version: glibc-2.31

Python version: 3.8.10 (default, Jun 2 2021, 10:49:15) [GCC 9.4.0] (64-bit runtime) Python platform: Linux-5.8.0-63-generic-x86_64-with-glibc2.29 Is CUDA available: True CUDA runtime version: 11.1.74 GPU models and configuration: GPU 0: Quadro P400 Nvidia driver version: 455.23.05 cuDNN version: Could not collect HIP runtime version: N/A MIOpen runtime version: N/A

Versions of relevant libraries: [pip3] numpy==1.21.0 [pip3] torch==1.9.0+cu111 [pip3] torchaudio==0.9.0 [pip3] torchvision==0.11.0a0+8d54022 [conda] Could not collect

Additional context

[mrsalehi]

@NicolasHug Yes, it works perfectly fine!

[NicolasHug]

@mrsalehi we recently merged https://github.com/pytorch/vision/pull/4254 which should fix this issue. Would you mind checking that it’s working properly now?