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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 cannot find H264 encoder

  31 juillet 2020, par Serban Stoenescu

  I am running ffmpeg from a program, and we built ffmpeg ourselves (we did not install it with package managers or pre-built stuff).
This is the command that is built :

  


  2020-07-31 12:14:11.942 INFO ffmpeg::FFTranscoder Executing: "../deps/ffmpeg/bin/ffmpeg" -y -r 26.062 -i ""/home/sstoenescu/Work/myproject/sample/myvideo.h264"" -c:v openh264 -vcodec h264 -movflags +faststart ""/home/sstoenescu/Work/myproject/sample/myvideo.mp4""


  


  The file myvideo.h264 is valid, I can play it with ffplay and I can run ffprobe on it without problems.
However, the command above gives this error :

  


  ffmpeg version N-98068-g16bdc2b541 Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 7 (Ubuntu 7.5.0-3ubuntu1~18.04)
  configuration: --arch=x86_64 --cpu=nehalem --disable-ffplay --enable-shared --enable-network --enable-gpl --enable-libx265 --enable-encoder=libx265 --disable-hwaccels --enable-hwaccel=h264_qsv --enable-hwaccel=h264_vaapi
  libavutil      56. 50.100 / 56. 50.100
  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
[h264 @ 0x5597c38defc0] error while decoding MB 86 45, bytestream -30
[h264 @ 0x5597c38defc0] concealing 2723 DC, 2723 AC, 2723 MV errors in I frame
Input #0, h264, from '/home/sstoenescu/Work/edvr/laba/gaoazar.h264':
  Duration: N/A, bitrate: N/A
    Stream #0:0: Video: h264 (High), yuv420p(progressive), 1920x1080 [SAR 1:1 DAR 16:9], 25 fps, 25 tbr, 1200k tbn, 50 tbc
Multiple -c, -codec, -acodec, -vcodec, -scodec or -dcodec options specified for stream 0, only the last option '-c:v h264' will be used.
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> h264 (h264_v4l2m2m))
Press [q] to stop, [?] for help
[h264 @ 0x5597c38e30c0] error while decoding MB 86 45, bytestream -30
[h264 @ 0x5597c38e30c0] concealing 2723 DC, 2723 AC, 2723 MV errors in I frame
[h264_v4l2m2m @ 0x5597c3905500] Could not find a valid device
[h264_v4l2m2m @ 0x5597c3905500] can't configure encoder
Error initializing output stream 0:0 -- Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height


  


  It used to work, I did not change anything in the command, so I'm assuming it's something in the way we build ffmpeg. We are using these flags : --enable-decoder=h264 --enable-encoder=h264_qsv    --enable-encoder=h264_vaapi --enable-decoder=h264 --enable-decoder=h264_qsv
Here's the full configuration :

  


  ./configure \
    --arch=x86_64 --cpu=nehalem \
    --disable-ffplay --enable-shared \
    --enable-network \
    --enable-gpl --enable-libx265 \
    --enable-encoder=libx265\
    --disable-hwaccels --enable-hwaccel=h264_qsv --enable-hwaccel=h264_vaapi \
     #--enable-encoder=libopenh264 \
     --enable-encoder=h264_qsv \
        --enable-encoder=h264_vaapi --enable-encoder=mjpeg --enable-encoder=gif \
    --enable-decoder=h264 --enable-decoder=h264_qsv \
        #--enable-decoder=libopenh264 
    --enable-libx264 \
        --enable-decoder=png \
    --enable-protocol=tcp \
    --enable-demuxer=rtsp --enable-demuxer=mov --enable-demuxer=h264 --enable-demuxer=image2 \
    --enable-muxer=mp4 --enable-muxer=h264 --enable-muxer=image2 \
    --prefix="./build"\
    --disable-doc


  


  Any ideas what could be wrong ?
Thanks.

  


  Regards,
Serban

  


• MobileFFMPeg Not converting mkv to Mp4

  7 mai 2020, par Jlee

  I'm currently running the following code on my device in order to convert all mkv files in a directory to an mp4. But for some reason no files are converted. I double checked the dir name and it is correct, is there something wrong with my syntax ?

  



  let path = self.documentsDir()
let url = URL(string: path.addingPercentEncoding(withAllowedCharacters: .urlQueryAllowed)!)
     var rc = MobileFFmpeg.execute("-i jellyfish.mkv -c:v libx264 -preset -slow -crf 22 -c:a copy youroutput.mp4")
          if (rc == RETURN_CODE_SUCCESS) {
               print("Command execution completed successfully.\n");
                } 
          else if (rc == RETURN_CODE_CANCEL) {
                print("Command execution cancelled by user.\n");
                } 
           else {
                print("Command execution failed with rc=%d and output=%@.\n", rc, MobileFFmpegConfig.getLastCommandOutput);
                }


  



  2020-05-07 13:36:02.782150-0400 WebmBrowser[8025:138754] ERROR: /Users/jlee/Library/Developer/CoreSimulator/Devices/8CD81B87-9E27-4F3C-8601-C76945FAD4D8/data/Containers/Data/Application/B7A0D956-3BAB-4203-82EE-5FDBF38B2F13/Documents/jellyfish.mkv: Invalid data found when processing input

Command execution failed with rc=%d and output=%@.