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• Determine FFmpeg codecs available for container

  19 juillet 2020, par CasualDemon

  I am looking to generate lists of supported video / audio / subtitle tracks for each type of container in a particular build of FFmpeg.

  


  For example, I want to avoid errors like Could not find tag for codec <> in stream #0, codec not currently supported in container

  


  I know I can list available codecs with ffmpeg -codecs, and find details about a muxer with ffmpeg -h muxer=<muxer></muxer> like ffmpeg -h muxer=matroska but that will only show default codecs, not all possible.

  


  Muxer matroska [Matroska]:
    Common extensions: mkv.
    Mime type: video/x-matroska.
    Default video codec: h264.
    Default audio codec: vorbis.
    Default subtitle codec: ass.


  


  Basically I want to run this command across all available muxers to build up a table like wikipedia's format comparison charts that is FFmpeg build specific. This is designed to go in a program that wraps around FFmpeg, and I need to know which formats are valid for each container / file extension per FFmpeg build.

  


  Thanks !

  


• How to determine if a ffmpeg subprocess has fallen

  9 avril 2020, par TiHan

  I have an issue

  



  I want to create a new ffmpeg process using subprocess.popen
find out his pid
and in the body of a python program to see if the process is alive or not

  



  args = shlex.split ('ffmpeg -i rtsp: //192.168.1.68: 8554 / mystream -f segment -strftime 1 -segment_time 5 13_REG1_CHANNEL3_% Y-% m-% d_% H-% M-% S-% s .mp3 ')
print (args)
proc = subprocess.Popen (args, stdout = subprocess.PIPE)
ch_pid = proc.pid
print (proc.pid)
proc.wait ()
print (proc.communicate ())
while (1):
 if (os.system (str ('kill -0 {PID}'). format (PID = ch_pid)) == 0):
   print ('proc is alive')
 else:
   break


  



  at while loop i tried to check this process pid via kill -0 pid
this command will return zero if everything is alright and process is running

  



  BUT

  



  IF ffmpeg will fall
there will be no changes

  



  kill -0 pid will continue to returning zero code that everything is good

  



  What should i do ?

  


• How do you determine the end of the file in a stream containing multiple streams ? (nodejs)

  26 décembre 2019, par Danielkent

  I would like to split an audio file into multiple segments using ffmpeg in an AWS Lambda (NodeJS) function.

  Due to the limitations of (and to optimise for) the lambda environment I would like to stream the audio into ffmpeg, perform the split on the audio file in the stream and then stream the now multiple smaller files out to s3.

  After doing some research I have found the AWS S3 SDK doesn’t support multiple file uploads in one stream. I could resolve this by finding the end of each new segment (file in the output stream) and creating a separate upload to s3.

  Is there a way to determine the end of a file in a stream (containing multiple files) ?

  (without saving it to the file system or loading it to memory).

  I have searched around and I can’t seem to find an answer.