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• Python/FFMPEG command line issues

  5 octobre 2011, par 12hys

  I have a problem with running an FFMPEG command from within a Python script. When I run the following command from the terminal, I can stream video and audio from my attached webcam (Logitech C310) and output to file "out.avi" without any errors.

  ffmpeg -f alsa -i default -itsoffset 00:00:00 -f video4linux2 -s 1280x720 -r 25 -i /dev/video0 out.avi

  When I run the same command in a Python script below,

  def call_command(command):
  
      subprocess.Popen(command.split(' '))
  
  
  
  call_command("ffmpeg -f alsa -i default -itsoffset 00:00:00 -f video4linux2 -s 1280x720 -r 25 -i /dev/video0 out.avi")

  it gives me the error :

  Input #0, alsa, from 'default':
  
    Duration: N/A, start: 1317762562.695397, bitrate: N/A
  
    Stream #0.0: Audio: pcm_s16le, 44100 Hz, 1 channels, s16, 705 kb/s
  
  [video4linux2 @ 0x165eb10]Cannot find a proper format for codec_id 0, pix_fmt -1.
  
  /dev/video0: Input/output error

  Could anyone shed some light on what could be going on here ? I've tried using os.system() as well as subprocess.call() and it gives me the same errors. I'm not sure where to start on what could be going wrong here. I tried searching for the "video4linux2 Cannot find a proper format for codec_id 0, pix_fmt -1" error, but couldn't find anything consistent.

  I've also tried putting the "ffmpeg -f..." command in a shell script "test.sh", and giving it executable permissions. I then open terminal, and run "./test.sh", and it works. When I try calling the command "./test.sh" from within my Python script, I'm left with the original error as before. This is the Python command I tried with the test.sh script :

  subprocess.call(["./test.sh"])

• Issues mapping multiple Axis RTSP streams using FFMPEG

  26 juin 2017, par Alex R

  I have an application built in C# that leverages FFMPEG to map 3 h264 RTSP streams from Axis cameras along with a gdigrab screen recording and saves everything to a file using this command :

   -rtsp_transport tcp -i rtsp://192.168.1.200/axis-media/media.amp -rtsp_transport tcp -i rtsp://192.168.2.200/axis-media/media.amp -rtsp_transport tcp -i rtsp://192.168.3.200/axis-media/media.amp -r 30 -f gdigrab -framerate 1 -i title="MainWindow"  -c copy -map 0 -vcodec copy -map 1 -metadata title="6-26-2017-4-22-PM- TEST VIDEO" -vcodec copy -map 2 -vcodec copy -map 3 -vcodec h264 -preset ultrafast C:\Users\*USERNAME*\6-26-2017-4-22-PM-cam1comb.mkv

  The issue that I’m having is that the Axis camera streams are out of sync with each other, with approximately a 3 second delay between the three streams. When I test the FFMPEG command with all inputs changed to this stream rtsp://mpv.cdn3.bigCDN.com:554/bigCDN/_definst_/mp4:bigbuckbunnyiphone_400.mp4 as well as the screen grab however, everything works perfectly.

• How to concatenate multiple MP4 videos with FFMPEG without audio sync issues ?

  21 avril 2024, par sb3k

  I have been trying to concatenate a number of MP4 clips (h264,aac) using the FFMPEG concat protocol documented here. The clips concatenate successfully, however there are multiple errors in the logs including :

  



  

  • Non-monotonous DTS in output stream

  


  • Past duration too large

  


  



  Additionally, it seems that the audio and video go slightly out of sync as more clips are added - though it is more noticeable on certain players (Quicktime & Chrome HTML5).

  



  Here is the code I am using, any tips would be appreciated !

  



  Convert each video to temp file

  



  ffmpeg -y -i <input file="file" /> -vcodec libx264 -acodec aac -f mpegts -bsf:v h264_mp4toannexb -mpegts_copyts 1 <temp file="file"></temp>

  



  Concat temp files

  



  ffmpeg -i concat  -map 0 -vcodec copy -aprofile aac_low -acodec aac -strict experimental -cutoff 15000 -vbsf aac_adtstoasc -b:a 32k <output file="file"></output>