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• How to properly abort av_seek_frame on FFmpeg ?

  5 mars 2021, par SuRGeoNix

  Normally, you wouldn't care aborting av_seek_frame as it would be really fast on a local file. However, in my case I use a custom AVIOContext for torrent streaming with custom read/seek functions and I'm not able to abort a single seek request !

  


  I've already tried interrupt callbacks (they will not be called at all), some timeouts (rw_timeout/timeout etc.) but by checking FFmpeg's code didn't find anything at all. My last chance was to try to return on read/seek functions an error (I've tried AVERROR_EXIT) which causes even more problems (memory leaks).

  


  The main issue is with Matroska formats that they need to resync (level-1) and they are trying to scan the whole file.

  


  Unfortunately, I'm using C# .NET with FFmpeg.Autogen bindings which means that I don't have low-level access to play around. My workaround is to re-open the whole format context in case on seek abort (to ensure that the player will continues to play at least)

  


  Hope you have a tip for me !

  


  (By the way for some http/hls web formats interrupt callbacks are supported)

  


• Have 2 blocking scripts interact with each other in linux

  18 novembre 2014, par Ortixx

  I have 2 blocking shell scripts which I want to have interact with each other. The scripts in question are peerflix (nodejs script) and ffmpeg (a simple bash script).

  What happens : Peerflix fires up, feeds data to ffmpeg bash scrip which terminates peerflix on completion.

  So once peerflix starts it outputs 2 lines and blocks immediately :

  [08:15 PM]-[vagrant@packer-virtualbox-iso]-[/var/www/test]-[git master] 
  
  $ node /var/www/test/node/node_modules/peerflix/app.js /var/www/test/flexget/torrents/test.torrent -r -q
  
  listening: http://10.0.2.15:38339/
  
  process: 9601

  I have to feed the listening address to the ffmpeg bash script :

  #!/bin/sh
  
  ffmpeg -ss 00:05:00 -i {THE_LISTENING_PORT} -frames:v 1 out1.jpg
  
  ffmpeg -ss 00:10:00 -i {THE_LISTENING_PORT} -frames:v 1 out2.jpg

  After the bash script is done I have to kill the peerflix script (hence me outputting the PID).

  My question is how do I achieve this ?

• Transcoding a Fast Video (think Snapchat, Instagram)

  4 juin 2018, par J DOe

  I am very new to the video world, but have noticed social media services.. particular snapchat and instagram do a great job of getting videos to load fast even on poorer connections. I know some of this is how the videos are transcoded.

  I have gathered some presets I think I should be using when transcoding with ffmpeg, but am not sure of what formats or other parts of it. I would love to hear what people think !

  ffmpeg()
  
      .input(remoteReadStream)
  
      .outputOptions('-preset fast')
  
      .outputOptions('-movflags +faststart')

  Other than that I am not entirely sure what else..