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• ffmpeg : adding a stream non-muxed stream with correct codec type tagging

  13 janvier 2021, par Hamish

  In common use, I believe ffmpeg requires inputs to be in a specified muxer format which contains one or more data streams which can be decoded with a codec supported by the demuxer associated with the format. I have a data stream (not audio or video) which is already encoded with a codec but is not muxed. How can I get this stream into the ffmpeg pipeline with the correct codec type assigned so that the muxer knows what to do with it ?

  


  I have tried streaming the data over UDP and specifying the data demuxer. With some combinations I get get it to say it's streaming, I can never get a player to connect, presumable because the output of mpegts is either null or invalid. Command line :

  


  ffmpeg -v verbose ^
-f flv -listen 1 -i rtmp://127.0.0.1:1101 ^
-f data -i udp://127.0.0.1:1300 ^
    -map 0:v -vcodec mpeg2video -map 1:d -f mpegts -mpegts_m2ts_mode 1  udp://localhost:1200


  


  Result (partial) :

  


  Input #0, flv, from 'rtmp://127.0.0.1:1101':
  Metadata:
    encoder         : Lavf58.29.100
  Duration: 00:00:00.00, start: 0.000000, bitrate: N/A
    Stream #0:0: Video: h264 (Constrained Baseline), 1 reference frame, yuv420p(progressive, left), 5760x1080 (5760x1088), 30 fps, 30 tbr, 1k tbn, 60 tbc
    Stream #0:1: Audio: mp3, 48000 Hz, stereo, fltp, 128 kb/s
Input #1, data, from 'udp://127.0.0.1:1300':
  Duration: N/A, start: 0.000000, bitrate: N/A
    Stream #1:0: Data: none
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> mpeg2video (native))
  Stream #1:0 -> #0:1 (copy)
Press [q] to stop, [?] for help
[h264 @ 00000180d48ae700] Reinit context to 5760x1088, pix_fmt: yuv420p
[graph 0 input from stream 0:0 @ 00000180d489dcc0] w:5760 h:1080 pixfmt:yuv420p tb:1/1000 fr:30/1 sar:0/1
[mpegts @ 00000180d5f64040] Cannot automatically assign PID for stream 1
Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument
Error initializing output stream 0:0 --
[AVIOContext @ 00000180d48b83c0] Statistics: 0 seeks, 0 writeouts
[AVIOContext @ 00000180d4882080] Statistics: 185593 bytes read, 0 seeks
[AVIOContext @ 00000180d5f469c0] Statistics: 204 bytes read, 0 seeks
Conversion failed!


  


  The codec type name is klv, which has the tag KLVA. It is only supported by the mpegts and mxf (de)muxers. I presume there must be a way of getting into the pipeline without having a valid mpegts or mxf stream in the first place otherwise we have a kind of paradox.

  


  I've tried specifying the codec on the input, but it fails validation, I guess because the data demuxer does not support it.

  


  Somehow mp4 files can be muxed from elemental streams (h264 and aac files), but I guess there must be some special case in the code to force the codec type based on the file extension.

  


  I would really love to do this from the command line with a public build but if this is absolutely not possible, I would also welcome some advice about it could be achieved from C++ code.

  


• Why does calling ffmpeg from python's popen break screen capture functionality ?

  4 mars 2016, par Jabb

  I am trying to create screen captures from mp4 files in python.
  Calling ffmpeg on the command line works fine. But as soon, as I issue the same command through python "popen", functionality breaks with an error that ffmpeg cannot find the moov atom. Can anyone explain this to me ?

  This is how I call ffmpeg from python :

  def ffmpegGetScreenshot(self,inputFilename,index,startTime):
  
      my_env = os.environ.copy()
  
      my_env.update({'PATH': '/bin:/usr/bin:/sbin:/usr/sbin:/usr/local/bin:/bin:/usr/bin:/sbin:/usr/sbin:/usr/local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin'})
  
  
  
      filename = inputFilename.split("/")[1]
  
      directory = inputFilename.split("/")[0]
  
      if os.path.isfile('videoscreenshots/'+filename+"_cs"+str(index)+".jpg"):
  
          return 'videoscreenshots/'+filename+"_cs"+str(index)+".jpg"
  
      print "get screenshots for: " + inputFilename
  
      command = [ FFMPEG_BIN,
  
                  '-y', 
  
                  '-i', inputFilename,
  
                  '-ss', str(int(startTime)),
  
                  '-vframes', '1',
  
                  #'-loglevel','quiet',
  
                  'videoscreenshots/'+filename+"_cs"+str(index)+".jpg"
  
                  ]
  
      pipe = sp.Popen(command, env=my_env,stdin = sp.PIPE,stdout = sp.PIPE, stderr=None)
  
      print command
  
  
  
      return 'videoscreenshots/'+filename+"_cs"+str(index)+".jpg"

  Result :

  ffmpeg version 2.7.2 Copyright (c) 2000-2015 the FFmpeg developers
  
    built with gcc 4.9.2 (Debian 4.9.2-10)
  
    configuration: --enable-gpl --enable-postproc --enable-swscale --enable-avfilter --enable-libmp3lame --enable-libvorbis --enable-libtheora --enable-libx264 --enable-libspeex --enable-shared --enable-pthreads --enable-libopenjpeg --enable-libfaac --enable-nonfree
  
    libavutil      54. 27.100 / 54. 27.100
  
    libavcodec     56. 41.100 / 56. 41.100
  
    libavformat    56. 36.100 / 56. 36.100
  
    libavdevice    56.  4.100 / 56.  4.100
  
    libavfilter     5. 16.101 /  5. 16.101
  
    libswscale      3.  1.101 /  3.  1.101
  
    libswresample   1.  2.100 /  1.  2.100
  
    libpostproc    53.  3.100 / 53.  3.100
  
  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x652120] moov atom not found
  
  videochunks/test.mp4: Invalid data found when processing input
  
  test.mp4

  This is the same command called on the console

  /usr/local/bin/ffmpeg -y -i videochunks/test.mp4 -ss 9 -vframes 1 videoscreenshots/test.mp4_cs2.jpg

  Result :

  root@3:/app# /usr/local/bin/ffmpeg -y -i videochunks/test.mp4 -ss 9 -vframes 1 videoscreenshots/test.mp4_cs2.jpg
  
  ffmpeg version 2.7.2 Copyright (c) 2000-2015 the FFmpeg developers
  
    built with gcc 4.9.2 (Debian 4.9.2-10)
  
    configuration: --enable-gpl --enable-postproc --enable-swscale --enable-avfilter --enable-libmp3lame --enable-libvorbis --enable-libtheora --enable-libx264 --enable-libspeex --enable-shared --enable-pthreads --enable-libopenjpeg --enable-libfaac --enable-nonfree
  
    libavutil      54. 27.100 / 54. 27.100
  
    libavcodec     56. 41.100 / 56. 41.100
  
    libavformat    56. 36.100 / 56. 36.100
  
    libavdevice    56.  4.100 / 56.  4.100
  
    libavfilter     5. 16.101 /  5. 16.101
  
    libswscale      3.  1.101 /  3.  1.101
  
    libswresample   1.  2.100 /  1.  2.100
  
    libpostproc    53.  3.100 / 53.  3.100
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'videochunks/test.mp4':
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2avc1mp41
  
      title           : Test
  
      composer        : Test
  
      album           : Test
  
      encoder         : Lavf56.36.100
  
    Duration: 00:00:10.01, start: 0.000000, bitrate: 520 kb/s
  
      Stream #0:0(und): Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p, 320x240 [SAR 4:3 DAR 16:9], 436 kb/s, 25 fps, 25 tbr, 25k tbn, 50 tbc (default)
  
      Metadata:
  
        handler_name    : VideoHandler
  
      Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 97 kb/s (default)
  
      Metadata:
  
        handler_name    : SoundHandler
  
  [swscaler @ 0x648260] deprecated pixel format used, make sure you did set range correctly
  
  Output #0, image2, to 'videoscreenshots/test_cs2.jpg':
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2avc1mp41
  
      title           : Test
  
      composer        : Test
  
      album           : Test
  
      encoder         : Lavf56.36.100
  
      Stream #0:0(und): Video: mjpeg, yuvj420p(pc), 320x240 [SAR 4:3 DAR 16:9], q=2-31, 200 kb/s, 25 fps, 25 tbn, 25 tbc (default)
  
      Metadata:
  
        handler_name    : VideoHandler
  
        encoder         : Lavc56.41.100 mjpeg
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (h264 (native) -> mjpeg (native))
  
  Press [q] to stop, [?] for help
  
  frame=    1 fps=0.0 q=3.9 Lsize=N/A time=00:00:00.04 bitrate=N/A
  
  video:11kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown

• ffmpeg detects a videofile path when it does not exist

  17 novembre 2020, par Nejc Kejzar

  this is boggling my mind. I am using ffmpeg to compress videos within the following python script :

  


  import re
import os

kage = 'MH5'
year = '2020'
month = '11'
day = '10'

# Set output dir; create it if it doesn't exist yet
downsampled_video_dir = home_data_dir + f'piCamera/downsampled_videos/{kage}/{year}/{month}/{day}/'
Path(downsampled_video_dir).mkdir(parents=True, exist_ok=True)
    
for i, video in enumerate(videos):
        # Set ffmpeg video compression terminal command and output directory for downsampled videos
        video_name = re.findall('\d+_\d+.mp4', video)[0]
        ds_output = downsampled_video_dir + video_name
        compress_command = f"ffmpeg -i {video} -vf scale={video_res[0]}:-2 {ds_output}"
        
        # Run ffmpeg video compression
        os.system(compress_command)


  


  videos is a list of full video paths of the videos that I wish to compress, and ds_output is a full path of where to write the compressed video. video_res[0] contains the desired height of the video with the following -2 automatically calculating the width so that the aspect ratio is preserved.

  


  For some reason when running this, ffmpeg detects some of the videos in the output directory as already existing and asks if I wish to overwrite them. The videos of course aren't there yet, so when I pass y, ffmpeg complains that no such file exists. Here is an example output for one of the problematic videos :

  


  ffmpeg -y -i '/home/piCamera/MH4/2020/11/10/20201110_085451.mp4' -vf scale=400:300  '/home/piCamera/downsampled_videos/MH4/2020/11/10/20201110_085451.mp4'
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
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/home/piCamera/MH4/2020/11/10/20201110_085451.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.20.100
  Duration: 00:03:58.84, start: 0.000000, bitrate: 1190 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 960x720, 1190 kb/s, 5 fps, 5 tbr, 10240 tbn, 20480 tbc (default)
    Metadata:
      handler_name    : VideoHandler
/home/piCamera/downsampled_videos/MH4/2020/11/10/20201110_085451.mp4: No such file or directory


  


  This happens with about 3 videos out of 53, the rest run normally. I've tried restarting the terminal, deleted the whole created downsampled_video_dir and run again, but no matter how many times I restart, the same videos are the problem. The only thing that appears to help is if I change the output directory name. Any ideas of why this strange error is happening ?

  


  This is being run on Ubuntu20 with python3.7.9 in a Jupyter Notebook.

  


  Many, many thanks for all the insights !