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• android chromecast mp4 by ffmpeg - shorter files play, some longer ones buffer but dont play

  20 octobre 2014, par Robert Rowntree

  Using Android SDK for CC, CCL, and ’styled receiver’ CC app.

  Video Files created by a heroku/ffmpeg bin that will play on any other client i tried (VLC ubuntu... ) and that will even play in chrome on a tab that’s being cast to chromecast will NOT PLAY natively on chromecast apps. They will appear as normal load in the UI of the app. CCL logs will show them buffering OK , but they never enter a play state from the buffering state. Debugging the receiver shows nothing unusual ( network tab, or Console ). They just buffer and dont play.

  If a slightly shorter version of the same , 2 ffmpeg input files is prepared and hosted, it seems to play fine in shorter versions under about 14 seconds long but will not play if a 16 second version is created.

  I used a number of chromecast apps including Allcast to test this. always got same result.

  2 dropbox mp4 links created with the ffmpeg cli here are below. A 14 second version of the output mp4 file plays fine on several Chromecast/android apps and a 16 second version fails.

  file len 14s

  file len 16s Wont play in CC apps

  ffprobe output on the files at :

  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'tst-nonplay-shorter_14s.mp4':
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2avc1mp41
  
      encoder         : Lavf54.29.105
  
    Duration: 00:00:14.07, start: 0.046440, bitrate: 311 kb/s
  
      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuvj420p, 1080x614 [SAR 1535:1539 DAR 100:57], 199 kb/s, 1 fps, 1 tbr, 16384 tbn, 2 tbc
  
      Metadata:
  
        handler_name    : VideoHandler
  
      Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 22050 Hz, mono, s16, 110 kb/s
  
      Metadata:
  
        handler_name    : SoundHandler

  and the file 2 seconds longer that wont play

  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'tst-nonplay-shorter_16s.mp4':
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2avc1mp41
  
      encoder         : Lavf54.29.105
  
    Duration: 00:00:16.06, start: 0.046440, bitrate: 286 kb/s
  
      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuvj420p, 1080x614 [SAR 1535:1539 DAR 100:57], 174 kb/s, 1 fps, 1 tbr, 16384 tbn, 2 tbc
  
      Metadata:
  
        handler_name    : VideoHandler
  
      Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 22050 Hz, mono, s16, 110 kb/s
  
      Metadata:
  
        handler_name    : SoundHandler

  Used ’qtfaststart’ and checked for MOOV ATOM issues and dont think that’s relevant.

  I think i can limit recordings in my app to 14 seconds and avoid problems that way, but I would like to understand what is up with the chromecast GETS on MP4’s generated by ffmpeg.

• ffmpeg encoding for 3.0 and 3.1 channels in Dolby Digital format (.ac3)

  4 novembre 2019, par CC2023

  I was able to encode .wav to .ac3 (Dolby Digital) via.zz ffmpeg for channel 2.0, 2.1, 4.0, 4.1, 5.0, 5.1, but not channel 3.0 and 3.1.

  When I played back .ac3 files on Onkyo 7.2 receiver, error on channel 3.0 and 3.1 was :

  3.0 channels :

  right channel ok

  left channel ok

  center channel played back at subwoofer

  3.1 channels :

  right channel ok

  left channel ok

  lfe channel ok

  center channel played back at surround left speaker (sL)

  This is command I used :

  ffmpeg -i 3_channel.wav -c:a ac3 3_channel.ac3    
  
  ffmpeg -i 3_1_channel.wav -c:a ac3 3_1_channel.ac3

  My ffmpeg version git-2019-10-28-68f623d

  Why I have successful encoding on channel 2.x, 4.x, 5.x, but not 3.x ? thanks ahead for any comments.

• FFMPEG : Output tiles onto a black background [closed]

  14 juin 2013, par MollyRazor

  I have the following command, which converts a video and also generates a 10x9
  tileset. Currently it gets the longer side and either generate a 90px wide or
  45px tall tiles. My problem is that each tile has to be 90x45 large, so in
  essence what I need is a properly resized and centered tile inside a black
  bounding box. How can I achieve this ?

  The resulting tile

  

  What I would like to achieve

  

  Actual command line

  ffmpeg -i K/vertical.mp4 .... vertical.out.mp4
  
  ffmpeg -i K/vertical.mp4 -an -vsync vfr \
  
  -vf select="isnan(prev_selected_t)+gte(t-prev_selected_t\,2)",scale="'if(gt(iw,ih),90,-1)':'if(gt(iw,ih),-1,45)'",tile="10x9" \
  
  -qscale:v 3 './f/f%03d.jpg'