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• How do you set up carrierwave-video with ffmpeg ?

  24 septembre 2013, par Maleckai

  This has been doing my head in for the past 2 days, and I just cannot seem to get it working.

  I am building a simple Rails app with the sole purpose of uploading & processing images and videos. I'm working on Ubuntu Linux.

  Here's the relevant gems in my Gemfile :

  gem 'delayed_job_active_record'
  
  gem 'carrierwave'
  
  gem 'carrierwave-video'
  
  gem 'carrierwave_backgrounder'
  
  gem 'mini_magick'
  
  gem 'streamio-ffmpeg'

  At first I was having problems with ffmpeg complaining about certain arguments (I determined this by taking the command the rails app attempted to run when it was to convert a video, and running it manually outside rails), which I discovered was because the version of ffmpeg I was using was 'too new'. So I downgraded to 1.2.1, which is what streamio-ffmpeg says is the only version of ffmpeg they're tested against.

  After that, I could run the command manually, fine. But whenever I tried to convert through the app, I'd get the error :

  Failed to transcode with FFmpeg. Check ffmpeg install and verify video is not corrupt or cut short. Original error: nil is not a symbol

  I did a bit of Googling on the error, and only came up with one relevant result, but nothing in there has helped my situation.

  I'm at a total loss at this point, and am not sure where I can go from here. I assume many of people have tried this before, so I'm hoping someone can guide me on the exact steps they took to get carrierwave-video & ffmpeg working together.

• Tools for investigating video corruption — ffmpeg / libavcodec

  11 juillet 2013, par Gopherkhan

  In my current work I'm trying to encode some images to h264 video using the FFMPEG's C library. The resulting video plays fine in VLC, but has no preview image. The video can play in VLC and Mplayer on ubuntu, but won't play on Mac or PC (in fact, it causes a "VTDecoderXPCService quit unexpectedly" error on Mac).

  If I run the resulting file through FFMPEG using the command line, the resulting file has a preview image, and plays correctly everywhere.

  Apparently the file that I get out of the program is corrupt in some weird place, but I don't have any output during my compilation or run to indicate where. I can't share my code at the moment (work code isn't open source yet :-( ), but I have tried a number of things :

  1. Writing only header and trailer data (av_write_trailer) and no frames
  2. writing frames only minus the trailer (using avcodec_encode_video2 and av_write_frame)
  3. Adjusting our time_base and frame pts values to encode only one frame per second
  4. Removing all variable frame rate code
  5. Numerous other variants that I won't bother you with here

  In creating my project, I've also followed the following tutorials :

  • Dr. Anger's FFMPEG tutorial
  • FFmpeg's Own Tutorials
  • An older tutorial from FFmpeg

  And consulted the deprecated ffmpeg functions list

  And compiled FFMPEG on ubuntu according to the official doc

  But every run of the program runs into the exact same problem.

  My question is, is there anything obvious that causes a programmatic run of FFMpeg to differ from a console run (e.g., an incomplete finalization, some threading issues, etc.) ? Like some obvious reason that a console run could repair a corrupted file ? Or is there a decent tool/method for inspecting a video file and finding the point of corruption ?

• Revision 7d9da93a97 : VP8D_GET_FRAME_CORRUPTED : check frame pointer if the decode of the first frame

  10 août 2014, par James Zern

  Changed Paths :
   Modify /test/decode_api_test.cc

  
   Modify /vp8/vp8_dx_iface.c

  
   Modify /vp9/vp9_dx_iface.c

  
  
  VP8D_GET_FRAME_CORRUPTED : check frame pointer

  if the decode of the first frame fails, frame_to_show may not be set.
  fixes a crash in vpxdec with corrupt data.

  Change-Id : I5ab9476d005778a13fd42a39d05876bb6c90a93c