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• ffmpeg - extract subtitles (which are unencrypted) when video is encrypted

  15 octobre 2015, par Alastair

  I have a .wtv file, recorded from Windows Media Center, that I’d like to extract the subtitles from. The video is encrypted, but the subtitles are not (something I’ve been able to verify by using CCExtractor with it). FFMpeg lists the video as such :

  Duration: 00:07:01.72, start: 2.214551, bitrate: 9154 kb/s
  
  Stream #0:0[0xcc](eng): Audio: ac3, 48000 Hz, 5.1(side), fltp, 384 kb/s
  
  Stream #0:1[0xcd]: Video: mpeg2video (Main), yuv420p(tv), 1920x1080 [SAR 1:1 DAR 16:9], Closed Captions, max. 25000 kb/s, 29.97 fps, 29.97 tbr, 10000k tbn, 59.94 tbc
  
  Stream #0:2[0xce]: Subtitle: eia_608

  When I try to run

  ffmpeg -i myvideofile.wtv -an -vn -map 0:2 -c:s:0 srt test.srt

  I see a lot of the following errors :

  [wtv @ 0x7fef79806e00] encrypted stream detected (st:1), decoding will likely fail
  
  Last message repeated 8 times
  
  [Closed caption Decoder @ 0x7fef7982cc00] Data Ignored since exceeding screen width

  and eventually :

  Output file is empty, nothing was encoded (check -ss / -t / -frames parameters if used)

  I don’t mind it being able to decode the video stream, but is that causing the closed caption error ? If it can’t decode the video it doesn’t know the screen width, perhaps ? Is it possible to set the closed caption decoder to ignore such errors and output anyway (it’s just in text format after all) ?

• Issue in displaying Large Video Files in MedisElement using ASP.NET JQuery

  13 novembre 2015, par SarahN

  There are some large .Mp4 files encoded with FFmpeg in another
  project .

  I use MediaElement.js to display the video for user (look after the video name in another server, copy it into a Webserver location , and play it) .
  for larger video files, they Cant be played . Does it mean MediaElement load whole Video file , and then play them ?
  What should I do for buffering separate section , to avoid this issue ?

  This is the code I use :

     if ($('#player1')) {
  
          player = new MediaElementPlayer("#player1",
  
                {
  
                  //...
  
                  alwaysShowControls: true,
  
                  success: function(mediaElement, domObject) {
  
                         mediaElement.play();
  
                                                             }
  
                });
  
          }

  I found this link MediaElement.js - Flash Video Wont Play Until Fully Loaded , I ’m not sure if its useful for me or not ?

  Please let me know if any solution comes into your mind, Thanks .

• Uploading & Processing Videos in Rails app on Heroku

  8 octobre 2015, par scientiffic

  In my Rails app, users can upload videos. The videos need to get converted to mp4s to ensure they can play across browsers, and they are hosted on AWS S3.

  If the video conversion (using ffmpeg) happens quickly, the resulting mp4 is rendered directly on the page so the user can immediately view the uploaded video. Sometimes, though the conversion takes long enough that I get Heroku H12 errors (request timeout), which prevents the video preview from appearing.

  Is there a recommended workflow for dealing with processing larger files in a Rails app using Heroku ?

  The option that immediately comes to mind is processing in a background task using something like Sidekiq, but then the user doesn’t receive feedback when the upload is complete.