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• ffmpeg extend (not resize) video size by adding box or border

  23 juin 2023, par RocketNuts

  Say I have a video of a peculiar resolution such as 1280x718 and I want to change this to 1280x720.

  



  But instead of interpolating 718 pixels vertically to 720, I'd rather just add one line at the top and bottom.

  



  So basically, I'm looking for a way to tell ffmpeg to create an output video of 1280x720, where input video of 1280x718 covers up the center, and all uncovered area is black or whatever.

  



  I guess we could call this the opposite of cropping. I know how to resize a video (with interpolation) but in this case I don't want to rescale or mess with the original content, just add a small border.

  


• avformat/hlsenc : correctly compute target duration

  7 juillet 2014, par Nicolas Martyanoff

  avformat/hlsenc : correctly compute target duration
  With HLS, the duration of all segments must be lower or equal to the target
  
  duration. Therefore floor(duration + 0.5) yields incorrect results.
  For example, for duration = 1.35, floor(duration + 0.5) yields 1.0, but the
  
  correct result is 2.0.
  Signed-off-by : Anssi Hannula <anssi.hannula@iki.fi>
  

  • [DH] libavformat/hlsenc.c

• Why this simple video streaming scheme does not work ?

  8 août 2014, par Vi.

  I’ve tried setting up simple webm video streaming scheme, based on ffserver and <video></video> element :

  # relevant part of ffserver.conf
  
  <stream>
  
      Feed feed1.ffm
  
  
  
      Format webm
  
      VideoFrameRate 15
  
      AVOptionVideo flags +global_header
  
      VideoSize 640x480
  
      VideoCodec libvpx
  
      VideoBitRate 800
  
  NoAudio
  
  </stream>
  
  
  
  # ffmpeg command line
  
  ffmpeg -f rawvideo -s 640x480 -i /dev/zero -vb 100000  http://vsodo.vi-server.org:8090/feed1.ffm
  
  
  
  # video element
  
  <video controls="controls" autoplay="autoplay">
  
      <source src="http://vsodo.vi-server.org:8090/feed1.webm" type="video/webm"></source>
  
      Your browser does not support the video tag.
  
  </video> 

  But it works only in few cases :

  • luakit - works (uses GStreamer) ;
  • uzbl - works ;
  • Firefox - fails (at least in versions 17, 24 and 26 and 31) ;
  • Chromium 31.0.1650.63 - fails ;
  • Google Chrome 27.0.1453.93 - fails ;
  • Built-in browser in Android 2.3 - fails.

  Failing browsers usually show the video length and the fact that there’s no audio track, but the video area stays black, not green as expected.

  This page lists "Partial support" or "Supported" for webm and video element. Usual players like VLC or mplayer work if specify http://vsodo.vi-server.org:8090/feed1.webm to them. Example video page also works (except of on Android 2.3).

  Why it can fail ? How do I troubleshoot browser-specific the <video></video> problems ?