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• mpegvideo : allocate sufficiently large scratch buffer for interlaced vid

  16 mai 2013, par Jindrich Makovicka

  mpegvideo : allocate sufficiently large scratch buffer for interlaced vid
  MPV_decode_mb_internal needs 3 * 16 * linesize bytes of scratch buffer
  For interlaced content, linesize is multiplied by two after the allocation
  
  of the scratch buffer, and the dest_cr pointer ends past the buffer.
  This patch makes ff_mpv_frame_size_alloc allocate a total of
  
  (aligned line_size) * 2 * 16 * 3 bytes, which suffices even for the
  
  interlaced case.
  CC:libav-stable@libav.org
  Signed-off-by : Jindrich Makovicka <makovick@gmail.com>
  
  Signed-off-by : Anton Khirnov <anton@khirnov.net>
  

  • [DH] libavcodec/mpegvideo.c

• know exactly the size of the converted video

  19 septembre 2014, par moderadorkl25

  I’m trying to know the size more accurately converted video using ffmpeg, I’m getting the actual size of the original video and output video
  and dividing the size of 2, the logic when I get the size of another video will multiply the value to know the result.

  the purpose of this is because I want to make a progress bar using php and ajax, so by my logic would be.

  <?
  
  $total = $select_result;// total original file
  
  $video = 'test.mp4';
  
  
  
  
  
  //loop ajax
  
  $getID3 = new getID3;
  
  $file = $getID3->analyze($video);
  
  $current = $file['filesize'];
  
  
  
  
  
  $a = $total / $current;
  
  $b = $a * 100;
  
  print number_format($b,0).'%';
  
  ?>

  ffmpeg command will always be this

  exec("ffmpeg -i $video -ar 22050 -ab 32 -f mp4 -s 320x240 teste1.mp4")

  but by my logic does not work, each video is a different value, it is possible to do this calculation ?

• Segmenting only specific parts of a video file

  30 mai 2013, par Christian P.

  I have some video files that I wish to serve up "dynamically", given the following workflow :

  1. Convert video from MP4 container to segmented .ts files with accompanying .m3u8 playlist
  2. Delete .ts files
  3. On request, generate .ts files (but only those requested, not for the entire video)

  I can generate .ts files for the entire video using ffmpeg using this command

  ffmpeg -y -i video.mp4 -c:a copy -bsf:a aac_adtstoasc -c:v copy -bsf:v h264_mp4toannexb -flags -global_header -map 0 -f segment -segment_time 10 -segment_list playlist.m3u8 -segment_format mpegts chunk_%03d.ts

  This is what I do in step 1 and it works just fine, video is playing fine. Due to disk constraints, I do not want to have two copies of every video (the original MP4 and the segmented .ts fies), so what I am trying to achieve is to find a command that will allow me to produce only the segments I need, on a per-request basis.

  Given the command above we may produce a sample playlist like this :

  #EXTM3U
  
  #EXT-X-VERSION:3
  
  #EXT-X-MEDIA-SEQUENCE:0
  
  #EXT-X-ALLOW-CACHE:YES
  
  #EXT-X-TARGETDURATION:12
  
  #EXTINF:11.261267,
  
  chunk_000.ts
  
  #EXTINF:11.261256,
  
  chunk_001.ts
  
  #EXTINF:7.507511,
  
  chunk_002.ts
  
  #EXTINF:11.261256,
  
  chunk_003.ts
  
  #EXTINF:11.261267,
  
  chunk_004.ts
  
  #EXTINF:7.507511,
  
  chunk_005.ts

  I have tried, using the -ss and -t flags available in ffmpeg, to create only a specific segments. For instance I might skip the first to segments by adding -ss 22.522523 (the total length of the two first segments), but this produces chunks that are not byte-for-byte identical to the original chunks and as such unusable (the video playback just stops). Is there a way to have ffmpeg (or another program) reproduce the same exact chunks, without producing all of them ?

  Short version : If I produce a playlist with chunks of an entire video (and accompanying .ts files), can I later reproduce a specific interval of those chunks that are byte-for-byte identical to the original chunks ?