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• Python complex string interpolation on shell command

  2 mai 2018, par Rex Low

  I have a shell command that I would like to execute, with a python script. It’s a combination of ffmpeg, grep, gawk and several other ffmpeg options.

  The command

  ffmpeg -i http://0.0.0.0:8080/stream/video.mjpeg -vcodec copy -map 0 -f segment -segment_time 2 -loglevel 40 -segment_format mp4 capture-%05d.mp4 2>&1 | grep --line-buffered -Eo "segment:.+ended" | gawk -F "'" '{print $2; system("")}'

  If you run this command on terminal, it should return a string

  capture-00001.mp4

  Now, my objective is to run this with subprocess on Python3. Since the command is rather complex with mixed single and double quotes, it needs to be treated correctly otherwise it will complain EOL while scanning string literal, invalid syntax, etc, etc.

  I have tried several string formating methods but none work. Below is one of the ways I’ve tried.

  Script

  import os
  
  import datetime
  
  import subprocess
  
  
  
  first = "segment:.+ended"
  
  second = "'"
  
  third = '{print $2; system("")}'
  
  
  
  if __name__ == "__main__":
  
      fScript = "ffmpeg -i http://0.0.0.0:8080/stream/video.mjpeg -vcodec copy -map 0 -f segment -segment_time 2 -loglevel 40 -segment_format mp4 capture-%05d.mp4 2>&1 | grep --line-buffered -Eo {} | gawk -F {} {}".format(first, second, third)
  
      try:
  
          result = subprocess.check_output(fScript, shell=True).decode('utf-8')
  
          print(result)
  
      except subprocess.CalledProcessError as e:
  
          print(e.output)

• ffmpeg - Error initializing complex filters

  11 mai 2019, par jinglei

  I’m trying to find out how to put two videos side-by-side and frame-by-frame and found this.

  However when I ran the command

  ffmpeg.exe -i test.avi -i test2.avi -r 60 -filter_complex "[0:v]scale=640:480, setpts=PTS-STARTPTS, pad=1280:720:0:120[left]; [1:v]scale=640:480, setpts=PTS-STARTPTS, pad=640:720:0:120[right]; [left][right]overlay=w; amerge,pan=stereo:c0code>

  I got the below errors

  [Parsed_pan_8 @ 000001b533e5fb00] This syntax is deprecated. Use '|' to separate the list items ('stereo|c0code>

  Can anyone help ?

• configure, avcodec/Makefile : Add new mpeg4audio CONFIG_EXTRA group

  14 décembre 2021, par Andreas Rheinhardt

  configure, avcodec/Makefile : Add new mpeg4audio CONFIG_EXTRA group
  This group is mainly for the users of *_mpeg4audio_get_config2() ;
  
  it is not for those who only use avpriv_mpeg4audio_sample_rates.
  
  This is in preparation for splitting the latter into a file of its own ;
  
  if there were no CONFIG_EXTRA group for *_mpeg4audio_get_config2()
  
  users, one would have to add a dependency to the new file for all
  
  these users on top of the existing dependency on mpeg4audio.o.
  Adding a new CONFIG_EXTRA group only takes effect after a reconfigure ;
  
  so in order to force a reconfigure some unnecessary headers from
  
  libavdevice/alldevices.c have been removed.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] configure
  • [DH] libavcodec/Makefile
  • [DH] libavdevice/alldevices.c