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• FFMPEG : Extracting 20 images from a video of variable length

  12 novembre 2013, par Vapire

  I've browsed the internet for this very intensively, but I didn't find what I needed, only variations of it which are not quite the thing I want to use.

  I've got several videos in different lengths and I want to extract 20 images out of every video from start to the end, to show the broadest impression of the video.

  So one video is 16m 47s long => 1007s in total => I have to make one snapshot of the video every 50 seconds.

  So I figured using the -r switch of ffmpeg with the value of 0.019860973 (eq 20/1007) but ffmpeg tells me that the framerate is too small for it...

  The only way I figured out to do it would be to write a script which calls ffmpeg with a manipulated -ss switch and using -vframes 1 but this is quite slow and a little bit off for me since ffmpegs numerates the images itself...

  Any suggestions or directions ?

  Thanks,
  Vapire

• When converting .mov to .flv video plays horizontally

  2 janvier 2014, par user291247

  When I record a video (.mov) through my iPhone it display vertically which is right.
  But after converting the .mov to .flv(using ffmpeg) it displays horizontally.

  My code :

  function convert_flv($vidtime,$infile, $outfile, $w = 0, $h = 0, $extra_infile = '', $extra_outfile = '') {
  
      $parms = '';
  
      if($w == 0 && $h == 0) {
  
          //$parms .= '-sameq ';
  
      } else {
  
          $parms = '-s {$w}x{$h} ';
  
      }
  
  
  
      if($vidtime==60) {
  
          $cmd = ffmpeg($infile, $outfile, $parms.' '.$extra_infile, '-t 00:01:00 -ar 22050 -r 15 -f flv  '.$extra_outfile);
  
      } else {
  
          $cmd = ffmpeg($infile, $outfile, $parms.' '.$extra_infile, '-t 00:04:00 -ar 22050 -r 15 -f flv  '.$extra_outfile);
  
      }
  
  
  
      print_r($cmd);
  
      return $cmd;
  
  }

• Missing audio and problems playing FLV video converted from 720p .mov file with FFMPEG

  18 novembre 2011, par undefined

  I have some .mov video files recorded from a JVC GC-FM1 HD video camera in 720p mode. I have FFMPEG running on a Linux box that I upload files to for encoding into FLV format. The video appears to be encoding ok, but there is no audio in the resulting FLV file. Also, when I play it back in Flash Player, in a browser or on Adobe Media Player, the video pauses at the start. It appears that Adobe Media Player waits for the progress bar to reach the end of the video before starting the playback - i.e. the video will load, the picture pauses, the progress bar seeks to the end as if the video were playing, then when it reaches the end the video picture starts. There is no audio on the video. I am noticing this in the video player I have built with Flash 8 using an FLVPlayback component and attached seekBar. The seek bar will start moving as if the video is playing but the picture remains paused.

  Here are some outputs from my FFMPEG log and the command I am using to encode the video.

  My FFMPEG command called from PHP :

  $cmd = 'ffmpeg -i ' . $sourcelocation.$filename.".".$fileext . '  -ab 96k -b 700k \
  
  -ar 44100 -s ' . $target['width'] . 'x' . $target['height'] . ' -ac 1 \
  
  -acodec libfaac ' . $destlocation.$filename.$ext_trans .' 2>&1';

  The output from my error log :

  FFmpeg version UNKNOWN, Copyright (c) 2000-2010 Fabrice Bellard, et al.
  
  built on Jan 22 2010 11:31:03 with gcc 4.1.2 20070925 (Red Hat 4.1.2-33)
  
  configuration: --prefix=/usr --enable-static --enable-shared --enable-gpl \
  
  --enable-nonfree --enable-postproc --enable-avfilter --enable-avfilter-lavf \
  
  --enable-libfaac --enable-libfaad --enable-libfaadbin --enable-libgsm \
  
  --enable-libmp3lame --enable-libvorbis --enable-libx264
  
  libavutil     50. 7. 0 / 50. 7. 0
  
  libavcodec    52.48. 0 / 52.48. 0
  
  libavformat   52.47. 0 / 52.47. 0
  
  libavdevice   52. 2. 0 / 52. 2. 0
  
  libavfilter    1.17. 0 /  1.17. 0
  
  libswscale     0. 9. 0 /  0. 9. 0
  
  libpostproc   51. 2. 0 / 51. 2. 0
  
  
  
  Seems stream 0 codec frame rate differs from container frame rate: 119.88 (120000/1001) -> 59.94 (60000/1001)
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'uploads/video/60974_v1.mov':
  
    Metadata:
  
      major_brand     : qt  
  
      minor_version   : 0
  
      compatible_brands: qt  
  
      comment         : JVC GC-FM1
  
      comment-eng     : JVC GC-FM1
  
    Duration: 00:00:30.41, start: 0.000000, bitrate: 4158 kb/s
  
      Stream #0.0(eng): Video: h264, yuv420p, 640x480 [PAR 1:1 DAR 4:3], 4017 kb/s, 59.94 fps, 59.94 tbr, 90k tbn, 119.88 tbc
  
      Stream #0.1(eng): Audio: aac, 48000 Hz, stereo, s16, 128 kb/s
  
  Output #0, rawvideo, to 'uploads/video/60974_v1.jpg':
  
      Stream #0.0(eng): Video: mjpeg, yuvj420p, 320x240 [PAR 1:1 DAR 4:3], q=2-31, 200 kb/s, 90k tbn, 59.94 tbc
  
  Stream mapping:
  
    Stream #0.0 -> #0.0
  
  Press [q] to stop encoding
  
  [h264 @ 0x8e67930]B picture before any references, skipping
  
  [h264 @ 0x8e67930]decode_slice_header error
  
  [h264 @ 0x8e67930]no frame!
  
  Error while decoding stream #0.0
  
  [h264 @ 0x8e67930]B picture before any references, skipping
  
  [h264 @ 0x8e67930]decode_slice_header error
  
  [h264 @ 0x8e67930]no frame!
  
  Error while decoding stream #0.0
  
  frame=    1 fps=  0 q=3.8 Lsize=      15kB time=0.02 bitrate=7271.4kbits/s dup=482 drop=0    
  
  video:15kB audio:0kB global headers:0kB muxing overhead 0.000000%

  Which are the important errors here ?

  B picture before any references, skipping ?
  decode_slice_header error ?
  no frame ?
  or
  Seems stream 0 codec frame rate differs from container frame rate : 119.88 (120000/1001) -> 59.94 (60000/1001)