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• Interpreting ffmpeg output in Python

  11 juin 2020, par Luka Milivojevic

  I started working in FFmpeg and I want to create a list that will contain start and end timestamps of silence intervals. I did print out these intervals using the FFmpeg but I need to format that output so it looks a bit more readable, so that is why I want to create a list out of it and then print it using a custom function. I know that I should go with regex here but I am not sure how should I write it nor how should I read the FFmpeg console output. My function for silence detection looks like :

  



  def detect_silence_ffmpeg():
    command = r"ffmpeg -i audio.wav -af silencedetect=n=-40dB:d=0.5 -f null - "
    subprocess.call(command, shell=True)


  



  And the output of this function on a 7 second long sample video is :

  



  ffmpeg version git-2020-06-03-b6d7c4c Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 9.3.1 (GCC) 20200523
  configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libsrt --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --disable-w32threads --enable-libmfx --enable-ffnvcodec --enable-cuda-llvm --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt --enable-amf
  libavutil      56. 49.100 / 56. 49.100
  libavcodec     58. 90.100 / 58. 90.100
  libavformat    58. 44.100 / 58. 44.100
  libavdevice    58.  9.103 / 58.  9.103
  libavfilter     7. 84.100 /  7. 84.100
  libswscale      5.  6.101 /  5.  6.101
  libswresample   3.  6.100 /  3.  6.100
  libpostproc    55.  6.100 / 55.  6.100
Guessed Channel Layout for Input Stream #0.0 : stereo
Input #0, wav, from 'audio.wav':
  Metadata:
    encoder         : Lavf58.44.100
  Duration: 00:00:07.34, bitrate: 1411 kb/s
    Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 44100 Hz, stereo, s16, 1411 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (pcm_s16le (native) -> pcm_s16le (native))
Press [q] to stop, [?] for help
Output #0, null, to 'pipe:':
  Metadata:
    encoder         : Lavf58.44.100
    Stream #0:0: Audio: pcm_s16le, 44100 Hz, stereo, s16, 1411 kb/s
    Metadata:
      encoder         : Lavc58.90.100 pcm_s16le
[silencedetect @ 00000202fc71e680] silence_start: 0
[silencedetect @ 00000202fc71e680] silence_end: 1.16374 | silence_duration: 1.16374
[silencedetect @ 00000202fc71e680] silence_start: 1.94558
[silencedetect @ 00000202fc71e680] silence_end: 3.41345 | silence_duration: 1.46787
[silencedetect @ 00000202fc71e680] silence_start: 3.8578
[silencedetect @ 00000202fc71e680] silence_end: 5.84844 | silence_duration: 1.99063
[silencedetect @ 00000202fc71e680] silence_start: 6.43653
size=N/A time=00:00:07.33 bitrate=N/A speed= 308x    
video:0kB audio:1264kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
[silencedetect @ 00000202fc71e680] silence_end: 7.33868 | silence_duration: 0.902154


  



  And this code should be implemented on an hour or so long videos so I really need to find a way to format this output a bit better than this. That would be it, any help would be much appreciated :)

  



  P.S : the idea is that this should work on Windows mainly, but if the cross-platform is possible too it would be great.

  


• FFmpeg installation on Raspberry Pi Zero W : Undefined references to __atomic

  3 février 2021, par MisterGray

  I'm trying to install ffmpeg on my Raspberry Pi Zero W, but I get several error messages.

  


  OS : Raspberry Pi OS (32-bit) Lite (May 2020)

  


  I have executed the following commands :

  


  sudo apt update
sudo apt full-upgrade
sudo apt install git
git clone https://github.com/FFmpeg/FFmpeg.git
cd FFmpeg
./configure --arch=armel --target-os=linux --enable-gpl --enable-omx --enable-omx-rpi --enable-nonfree
make -j2
sudo make install


  


  Output of last command :

  


  ...
LD      ffmpeg_g
/usr/bin/ld: libavformat/libavformat.a(fifo.o): in function `fifo_init':
/home/pi/FFmpeg/libavformat/fifo.c:519: undefined reference to `__atomic_store_8'
/usr/bin/ld: libavformat/libavformat.a(fifo.o): in function `fifo_write_trailer':
/home/pi/FFmpeg/libavformat/fifo.c:624: undefined reference to `__atomic_fetch_add_8'
/usr/bin/ld: /home/pi/FFmpeg/libavformat/fifo.c:631: undefined reference to `__atomic_store_8'
/usr/bin/ld: libavformat/libavformat.a(fifo.o): in function `fifo_thread_write_packet':
/home/pi/FFmpeg/libavformat/fifo.c:188: undefined reference to `__atomic_fetch_sub_8'
/usr/bin/ld: libavformat/libavformat.a(fifo.o): in function `fifo_consumer_thread':
/home/pi/FFmpeg/libavformat/fifo.c:457: undefined reference to `__atomic_load_8'
/usr/bin/ld: libavformat/libavformat.a(fifo.o): in function `fifo_write_packet':
/home/pi/FFmpeg/libavformat/fifo.c:597: undefined reference to `__atomic_fetch_add_8'
collect2: error: ld returned 1 exit status
make: *** [Makefile:114: ffmpeg_g] Error 1


  


  Maybe another package is missing ? Do I have to change anything in the config ?

  


• Why are there vaapi filters that exist in libavfilter but do not exist in my compiled version of ffmpeg ?

  13 juin 2020, par John Allard

  I've compiled the most recent snapshot of ffmpeg with vaapi enabled

  



  $ ffmpeg -hwaccesls
ffmpeg version N-98129-g0b182ff Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.12) 20160609
  configuration: --disable-debug --disable-doc --disable-ffplay --enable-shared --enable-avresample --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-gpl --enable-libass --enable-fontconfig --enable-libfreetype --enable-libvidstab --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx265 --enable-libxvid --enable-libx264 --enable-nonfree --enable-openssl --enable-libfdk_aac --enable-postproc --enable-small --enable-version3 --enable-libzmq --extra-libs=-ldl --prefix=/opt/ffmpeg --enable-libopenjpeg --enable-libkvazaar --enable-libaom --extra-libs=-lpthread --enable-libsrt --enable-vaapi --extra-cflags=-I/opt/ffmpeg/include --extra-ldflags=-L/opt/ffmpeg/lib
  libavutil      56. 54.100 / 56. 54.100
  libavcodec     58. 92.100 / 58. 92.100
  libavformat    58. 46.101 / 58. 46.101
  libavdevice    58. 11.100 / 58. 11.100
  libavfilter     7. 86.100 /  7. 86.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  8.100 /  5.  8.100
  libswresample   3.  8.100 /  3.  8.100
  libpostproc    55.  8.100 / 55.  8.100
Hardware acceleration methods:
vaapi


  



  I know that vaapi is working because I can use it for hardware decoding and encoding of h264 videos. I can see some vaapi filters as well

  



  $ ffmpeg -filters | grep vaapi
 ... deinterlace_vaapi V->V       (null)
 ... denoise_vaapi     V->V       (null)
 ... procamp_vaapi     V->V       (null)
 ... scale_vaapi       V->V       (null)
 ... sharpness_vaapi   V->V       (null)


  



  However, I notice that this list is missing the filter that I'm specifically looking for, namely , transpose_vaapi. If you look in the libavfilter source code you'll see the following

  



  This shows the transpose_vaapi filter defined in the allfilters.c file
https://github.com/FFmpeg/FFmpeg/blob/master/libavfilter/allfilters.c#L414

  



  This shows the transpose_vaapi filter source code
https://github.com/FFmpeg/FFmpeg/blob/master/libavfilter/vf_transpose_vaapi.c

  



  If the filter is defined in source code, it's defined in allfilters.c, and I've compiled ffmpeg from this source with vaapi enabled, why can I not use this filter with ffmpeg ?

  



  $ ffmpeg -y -hide_banner -nostats -loglevel error \
    -hwaccel vaapi -hwaccel_device /dev/dri/renderD128 -hwaccel_output_format vaapi \
    -i ./test_video.mp4 \
    -vf 'format=nv12,transpose_vaapi=2' \
    -c:v h264_vaapi \
    /tmp/rotated_video.mp4
[AVFilterGraph @ 0xf14000] No such filter: 'transpose_vaapi'
Error reinitializing filters!
Failed to inject frame into filter network: Invalid argument


  



  EDIT -

  



  Looking through the source code for vf_transpose_vaapi.c I see the following logic

  



      if (!pipeline_caps.rotation_flags) {
        av_log(avctx, AV_LOG_ERROR, "VAAPI driver doesn't support transpose\n");
        return AVERROR(EINVAL);
    }


  



  that's inside of the transpose_vaapi_build_filter_params function which is part of the filter initialization process. I guess it's possible that, if that call failed, the filter would fail to be built and it would not be registered as a valid filter ? This seems like something that would happen at runtime when I attempt to run the filter rather than something that would happen at compile time when setting which filters are defined.