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• what is a good way to calculate frame rate using of a video ffmpeg ?

  20 septembre 2013, par user1914692

  I find three possible ways :

  (Option 1)
  inVStruct.inVideoStream->r_frame_rate

  [comment :] correct for some videos. Not always correct.
  it is libavformats guess, not exact. (see http://ffmpeg.org/pipermail/ffmpeg-devel/2005-May/003079.html )

  (Option 2)
  (double) inVStruct.inVideoStream->r_frame_rate.num / (double) inVStruct.inVideoStream->r_frame_rate.den

  [comment :] correct for some videos. Not always correct.

  (Option 3)
  (double) inVStruct.inCodecContext->time_base.den / (double) inVStruct.inCodecContext->time_base.num / inVStruct.inCodecContext->ticks_per_frame) ;

  [comment :] correct for some videos. Not always correct.

  Please recommend one for all video files.

• what is wrong with this ffmpeg command ?

  16 juillet 2013, par kheya

  I am trying to convert 3gp movie to H264 video (mp4)
  This is what I am using :

  ffmpeg -i file8.3gp -vcodec libx264 -preset slow -vf scale="720:trunc(ow/a/2)*2" -threads 0 -acodec libvo_aacenc -b:a 128k "file8.mp4"

  The problem is original file is 28kb but after conversion I get 155kb mp4 file
  Why is the file so bloated - is that because of the size or some other option ?

  Here is what I see on 3gp input file : NOTE THE BIT RATE IS 46 KB/S

  libavutil      52. 39.100 / 52. 39.100
  
    libavcodec     55. 18.102 / 55. 18.102
  
    libavformat    55. 12.102 / 55. 12.102
  
    libavdevice    55.  3.100 / 55.  3.100
  
    libavfilter     3. 80.101 /  3. 80.101
  
    libswscale      2.  3.100 /  2.  3.100
  
    libswresample   0. 17.102 /  0. 17.102
  
    libpostproc    52.  3.100 / 52.  3.100
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'file8.3gp':
  
    Metadata:
  
      major_brand     : 3gp5
  
      minor_version   : 256
  
      compatible_brands: 3gp53gp4
  
      creation_time   : 2005-10-28 17:36:40
  
    Duration: 00:00:04.93, start: 0.000000, bitrate: 46 kb/s
  
      Stream #0:0(eng): Audio: amr_nb (samr / 0x726D6173), 8000 Hz, mono, flt, 8 k
  
  b/s
  
      Metadata:
  
        creation_time   : 2005-10-28 17:36:40
  
        handler_name    : Apple Sound Media Handler
  
      Stream #0:1(eng): Video: mpeg4 (Simple Profile) (mp4v / 0x7634706D), yuv420p
  
  , 176x144 [SAR 1:1 DAR 11:9], 35 kb/s, 15 fps, 15 tbr, 600 tbn, 1k tbc
  
      Metadata:
  
        creation_time   : 2005-10-28 17:36:40
  
        handler_name    : Apple Video Media Handler

  Here is what I see on mp4 output file : NOTE THE BIT RATE IS 243 KB/S

  libavutil      52. 39.100 / 52. 39.100
  
    libavcodec     55. 18.102 / 55. 18.102
  
    libavformat    55. 12.102 / 55. 12.102
  
    libavdevice    55.  3.100 / 55.  3.100
  
    libavfilter     3. 80.101 /  3. 80.101
  
    libswscale      2.  3.100 /  2.  3.100
  
    libswresample   0. 17.102 /  0. 17.102
  
    libpostproc    52.  3.100 / 52.  3.100
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'file8.mp4':
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2avc1mp41
  
      encoder         : Lavf55.12.102
  
    Duration: 00:00:05.20, start: 0.200000, bitrate: 243 kb/s
  
      Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 720x588 [
  
  SAR 539:540 DAR 11:9], 240 kb/s, 15 fps, 15 tbr, 15360 tbn, 30 tbc
  
      Metadata:
  
        handler_name    : VideoHandler
  
      Stream #0:1(eng): Audio: aac (mp4a / 0x6134706D), 8000 Hz, mono, fltp, 10 kb
  
  /s
  
      Metadata:
  
        handler_name    : SoundHandler
  
  At least one output file must be specified

• How to convert audio stream from PureTool/CVS video ?

  1er janvier 2013, par Mark

  I apologize if there is a better place to post this. I recently came across a couple CVS single-use video cameras that I had been using back in 2005. I still have the USB cable I made and now that I've switched to Mac I can use Puretool to extract the old videos from the cameras. The problem I'm having is that I can only hear the audio when viewing the videos with VLC media player. I read on PureTools site, a common problem is that the audio codec used is incompatible with Quicktime and the audio stream needs to be converted. There is a link on their site to a program called FixSound which is purported to fix this, but the link is dead and I've been unable to find any further information about this. If anyone could point me in the right direction, I'd be very grateful. All the videos I'm dealing with are from the first year of my son's life and I'd really like to be able to archive them in a more uniform format. I would think this would be possible to do using Adobe Audition or some other program in Adobe's CS6 Master Collection but I've only dealt with Photoshop, Illustrator, Dreamweaver, Flash & Fireworks. I have no experience with audio or video yet.

  Thanks,

  Mark