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• 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 ?

• ffmpeg "Requested output format 'decklink is not a suitable format'"

  9 février 2018, par user3104363

  I am trying to play a video using ffmpeg and decklink.
  I compiled ffmpeg from ffmpeg repo.
  I am working in ubuntu 16.04 lts.

  Here is my command :

  ./ffmpeg -err_detect ignore_err -threads 0 -re -i ./sample_1080_50i.ts -bufsize 1M -vf yadif -format_code Hi50 -f decklink -preroll 0.7 -pix_fmt uyvy422 'DeckLink Studio 4K'

  The result is :

  ffmpeg version N-89978-gcb97400 Copyright (c) 2000-2018 the FFmpeg developers
  
    built with gcc 5.1.1 (Ubuntu 5.1.0-0ubuntu11~10.04.2)
  
    configuration: --prefix=/home/sarslan/ffmpeg_build --pkg-config-flags=--static --extra-cflags='-I/home/sarslan/ffmpeg_build/include -I/home/sarslan/ffmpeg_sources/Blackmagic_DeckLink_SDK_10.9.5/Linux/include' --extra-ldflags=-L/home/sarslan/ffmpeg_build/lib --extra-libs='-lpthread -lm' --bindir=/home/sarslan/bin --enable-gpl --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-nonfree --enable-static --disable-shared --enable-decklink --enable-ffplay
  
    libavutil      56.  7.100 / 56.  7.100
  
    libavcodec     58. 10.100 / 58. 10.100
  
    libavformat    58.  9.100 / 58.  9.100
  
    libavdevice    58.  1.100 / 58.  1.100
  
    libavfilter     7. 11.101 /  7. 11.101
  
    libswscale      5.  0.101 /  5.  0.101
  
    libswresample   3.  0.101 /  3.  0.101
  
    libpostproc    55.  0.100 / 55.  0.100
  
  Input #0, mpegts, from './sample_1080_50i.ts':
  
    Duration: 00:05:00.08, start: 1.437333, bitrate: 4675 kb/s
  
    Program 1 
  
      Metadata:
  
        service_name    : Service01
  
        service_provider: FFmpeg
  
      Stream #0:0[0x100]: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p(top first), 1920x1080 [SAR 1:1 DAR 16:9], 25 fps, 25 tbr, 90k tbn, 50 tbc
  
      Stream #0:1[0x101](eng): Audio: aac (LC) ([15][0][0][0] / 0x000F), 48000 Hz, stereo, fltp, 123 kb/s
  
  [NULL @ 0xb2ed180] Requested output format 'decklink' is not a suitable output format
  
  DeckLink Studio 4K: Invalid argument

  I think, this error is weird.
  I enabled decklink support with —enable-decklink, and I also check ffmpeg documentation decklink part.’decklink’ is used with -f option in every example.

  Then I check the command line, and I can’t find any error with the command.
  Do you have any idea what the problem is ?

  Thanks and best regards,

• Facebook live video can only be previewed while streaming my Mac screen

  24 janvier 2017, par iownthegame

  I use the following ffmpeg command to share my screen streaming to Facebook.

  

  ffmpeg -f avfoundation -r 10 -video_size 352x288 -i "0" -c:v h264 -f flv 
  
  "rtmp://rtmp-api.facebook.com:80/rtmp/1269140699772419?ds=1&a=AaYsXcYcdHQrrrUF"

  then I can see the video preview scenes
  

  however, once I press the ’Go Live’ button, and go to my facebook page, I can find a post said I am Live Now. When I press the ’play button’, there are only black scenes that last for 1 2 seconds, and the video ends.

  

  And there is also a weird thing, the video can be played when I end up the live stream. When refreshing the page, I can find a post said I was Live, the video of this post can be played successfully.

  Anyone knows why the video can be watched when previewing and finishing live but not the exact live moment ?

  [updated]

  During the live streaming period, if I press the play button, there are only 1 2 seconds black scenes and the live stream ends.
  

  However if I press the video frame again, another modal pops up then I can see the live streaming. Is it a facebook bug ?