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• avfilter/yadif_common : Add field type tracking to help bwdif

  4 novembre 2018, par Philip Langdale

  avfilter/yadif_common : Add field type tracking to help bwdif
  The bwdif filter can use common yadif frame management if we track
  
  when a field is the first or last field in a sequence. While this
  
  information is not used by yadif, the added benefit of removing the
  
  duplicated frame management logic makes it worth tracking this state
  
  in the common code.
  

  • [DH] libavfilter/yadif.h
  • [DH] libavfilter/yadif_common.c

• php exec won't execute what is executable in console regarding audio and video

  29 novembre 2018, par FJ-web

  I have php to run a shell command to start an audio/video stream via ffmpeg. I tried the syntax in the console (as the same user as php [www-data] and from the same location as the php-script :

  pi@raspberrypi:/var/www/html/ $ sudo -H -u www-data ffmpeg {parameters}

  This works nicely. Both audio and video is visible on youtube. When I execute from php with exactly the same parameters

  $pid = exec("ffmpeg {parameters} 2> out.txt");

  the response is

  cannot open audio device hw:1,0 (No such file or directory)

  My first guess was that this had something to do with users and groups, but I can’t tell what. I even put www-data in the sudo group. Still not working.

  If I do

  exec("whoami 2> user.txt");

  the file user.txt is created (with owner www-data) but remains empty. Can anyone help me out ?

  UPDATE
  When I reboot the pi it works only one time. I think that somehow after closing the stream

  exec("kill -9 ".$pid);

  the audio is still busy. The error message is changed in

  cannot open audio device hw:1,0 (Device or resource busy)

  The video (via uv4l : localhost:port/stream/video.mjpeg) is available.

• FFMPEG - What are some recommended parameters for x265 (libx265) ?

  7 janvier 2019, par dd_code

  I am working on re-encoding some footage (x264), including some grainy footage. I am interested in CRF-only bitrate management (I want to avoid artifacts during demanding scenes).
  What are recommended parameters to be set instead of leaving them at their defaults ?

  Here is what I got so far, pretty simple :

  ffmpeg -i in.mkv -vf unsharp=3:3:1 -c:v libx265 -tune:v grain -crf 24 -c:a copy out.mkv

  (this example has grain tune as many files are grainy, and without it it washes it out and all the "detail by noise" is lost + I am applying a light sharpening filter, I find there is always a room to sharpen a bit without causing noticeable sharpening artifacts)

  If I am not mistaken all the params one does consider are ones contained in the presets, but is there some other or one of those which is a good practice to adjust manually to achieve a better result ? I was wondering specifically about P,I,B-frames and AQ (but I guess there are some other as well).