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• Get PID of process in one line

  17 décembre 2017, par Dovid Bender

  I have a bash script that is called by a phone system that gets some audio from a URL and (using ffmpeg, mplayer etc.) then pipes it back to the application. The file can have several URL’s that are called so if the first one say goes off line or gives a 404 it will go to the next line.

  I have an issue where some times the server will produce content however there is no audio. In such a case I want to kill the current PID of ffmpeg, mplayer etc. so that the script should move on.

  I can’t foreground it and get the last PID since once it’s ran in the foreground the media is no longer being piped to the application calling it. I can’t use exec in the beginning since if I then issue a kill to the PID the script dies which I don’t want.

  The script looks something like this :

  #!/bin/bash
  
  
  
  /usr/bin/ffmpeg  -i 'http://1.1.1.1/soft_music' -vn -ar 8000 -ac 1 -f s16le -
  
  /usr/bin/ffmpeg  -i 'http://2.2.2.2/soft_music' -vn -ar 8000 -ac 1 -f s16le -

  I assume I need to add something that will allow me to log the pid of the current ffmpeg command running so my external script can get it and kill it. Once that’s done it will go to the next line and try the next stream from 2.2.2.2

• FFMPEG Stdout Line

  23 janvier 2023, par ai manifest

  I'm just wondering why Google Colab doesn't show FFMPEG's STDOUT line, showing the frame progress, fps, duration, time elapsed, etc. Jupyter notebooks and jupyter lab shows it, so I'm not sure why colab doens't. Thanks in advance.

  


  When running the ffmpeg command, (!ffmpeg -i input.mp4 output.mp4), there is no stdout line in google colab, but if run in jupyter notebooks, the stdout lines show. Just curious why this is.

  


• avcodec/jpeglsenc : Only use one line at a time as spare buffer

  3 septembre 2020, par Andreas Rheinhardt

  avcodec/jpeglsenc : Only use one line at a time as spare buffer
  ls_encode_line() encodes one line of input from left to right and
  
  to do so it uses the values of the left, upper left, upper and upper
  
  right pixels for prediction (i.e. the values that a decoder gets when it
  
  decodes the already encoded part of the picture). So a simple algorithm
  
  would use a buffer that can hold two lines, namely the current line as
  
  well as the last line and swap the pointers to the two lines after
  
  decoding each line. Yet if one is currently encoding the pixel with
  
  index k of a line, one doesn't need any pixel with index < k - 1 of the
  
  last line at all and similarly, no pixels with index >= k have been
  
  written yet. So the overlap in the effective lifetime is pretty limited
  
  and since the last patch (which stopped reading the upper left pixel and
  
  instead reused the value of the upper pixel from the last iteration of
  
  the loop) it is inexistent. Ergo one only needs one line and doesn't
  
  need to swap the lines out.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
  

  • [DH] libavcodec/jpeglsenc.c