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• aacdec : reorder multiuplications to make code safer against too large input values.

  25 octobre 2012, par Michael Niedermayer

  aacdec : reorder multiuplications to make code safer against too large input values.

• avcodec/jpeg2000dwt : Move large arrays used in the test code away from the stack

  22 juin 2015, par Michael Niedermayer

  avcodec/jpeg2000dwt : Move large arrays used in the test code away from the stack
  This should avoid problems on systems with little stack space and fix some crashes
  
  in fate
  crash found-by : jamrial
  
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavcodec/jpeg2000dwt.c

• FFmpeg splitting large files

  1er février 2016, par Yusaf Khaliq

  I need to split a large video file into multiple pieces quickly and without files with errors. The basic idea is, I have a 2GB video file which I want to change to multiple formats. I have read some encoders can not make use of more than 1 core when encoding to a different format. So I had the idea to split the large file (which is very quick) into 4/8 pieces depending on how many cores I have available on individual servers. re-encode each piece to a new format and use these to display video in sequence.

  so

  testfile.mp4

  becomes

  1. testfile_piece_1.mp4
  2. testfile_piece_2.mp4
  3. testfile_piece_3.mp4
  4. testfile_piece_4.mp4

  these can then be individually be converted.

  The solution should not be format specific. However I have found issues with mp4 files.

  I have tried the command below, which works really well and fast but creates files with errors.

  ffmpeg -i testfile.mp4 -ss 00:00:00 -t 00:20:00 -c copy testfile_piece_1.mp4

  When I play the testfile_piece_1.mp4 on VLC it works fine. An issue arises when converting the split file to a different height and width mp4 file. I would get an error similar to "moov atom not found"

  I tried adding -movflags faststart with no luck

  I then came across this library https://code.google.com/archive/p/moovrelocator/ which fixed the moov issue but I would then get an error with regards to aac "Error while opening encoder for output stream #0.0 - maybe incorrect parameters such as bit_rate, rate, width or height"

  The other way of splitting the files is useless but involved re-encoding the file. not too bad for smaller file size but the 2GB file would probably take days to complete.

  Is there a way to split the largr file quickly without producing files with errors ? I have been working on it for days with no luck.

  Console output for comment - FFmpeg splitting large files

  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/usr/share/nginx/html/uploads/testfile01.mp4':
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2avc1mp41
  
      encoder         : Lavf56.36.100
  
    Duration: 00:05:02.08, start: 302.120000, bitrate: 3254 kb/s
  
      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709)                                  , 1920x1080 [SAR 1:1 DAR 16:9], 3252 kb/s, 25 fps, 25 tbr, 12800 tbn, 50 tbc (de                                  fault)
  
      Metadata:
  
        handler_name    : VideoHandler
  
  [libx264 @ 0x165ffc0] width not divisible by 2 (853x480)
  
  Output #0, mp4, to '/usr/share/nginx/html/uploads/testfile01_480.mp4':
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2avc1mp41
  
      encoder         : Lavf56.36.100
  
      Stream #0:0(und): Video: h264, none, q=2-31, 128 kb/s, SAR 2560:2559 DAR 0:0                                  , 25 fps (default)
  
      Metadata:
  
        handler_name    : VideoHandler
  
        encoder         : Lavc56.41.100 libx264
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
  
  Error while opening encoder for output stream #0:0 - maybe incorrect parameters                                   such as bit_rate, rate, width or height

  console output 2

  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/usr/share/nginx/html/uploads/testfile.mp4':
  
    Metadata:
  
      major_brand     : dash
  
      minor_version   : 0
  
      compatible_brands: iso6avc1mp41
  
      creation_time   : 2016-01-24 04:26:37
  
    Duration: 01:15:58.08, start: 0.000000, bitrate: 3163 kb/s
  
      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709), 1920x1080 [SAR 1:1 DAR 16:9], 3161 kb/s, 25 fps, 25 tbr, 90k tbn, 50 tbc (default)
  
      Metadata:
  
        creation_time   : 2016-01-24 04:26:37
  
        handler_name    : VideoHandler
  
  [segment @ 0x1197060] Codec for stream 0 does not use global headers but container format requires global headers
  
  [mp4 @ 0x11512a0] Codec for stream 0 does not use global headers but container format requires global headers
  
  Output #0, segment, to '/usr/share/nginx/html/uploads/testfile%02d.mp4':
  
    Metadata:
  
      major_brand     : dash
  
      minor_version   : 0
  
      compatible_brands: iso6avc1mp41
  
      encoder         : Lavf56.36.100
  
      Stream #0:0(und): Video: h264 (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 3161 kb/s, 25 fps, 25 tbr, 12800 tbn, 25 tbc (default)
  
      Metadata:
  
        creation_time   : 2016-01-24 04:26:37
  
        handler_name    : VideoHandler
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)
  
  Press [q] to stop, [?] for help
  
  [mp4 @ 0x11512a0] Codec for stream 0 does not use global headers but container format requires global headers
  
  [mp4 @ 0x11512a0] Codec for stream 0 does not use global headers but container format requires global headers
  
  [mp4 @ 0x11512a0] Codec for stream 0 does not use global headers but container format requires global headers
  
  [mp4 @ 0x11512a0] Codec for stream 0 does not use global headers but container format requires global headers
  
  [mp4 @ 0x11512a0] Codec for stream 0 does not use global headers but container format requires global headers
  
  [mp4 @ 0x11512a0] Codec for stream 0 does not use global headers but container format requires global headers
  
  [mp4 @ 0x11512a0] Codec for stream 0 does not use global headers but container format requires global headers
  
  [mp4 @ 0x11512a0] Codec for stream 0 does not use global headers but container format requires global headers
  
  [mp4 @ 0x11512a0] Codec for stream 0 does not use global headers but container format requires global headers
  
  [mp4 @ 0x11512a0] Codec for stream 0 does not use global headers but container format requires global headers
  
  [mp4 @ 0x11512a0] Codec for stream 0 does not use global headers but container format requires global headers
  
  [mp4 @ 0x11512a0] Codec for stream 0 does not use global headers but container format requires global headers
  
  [mp4 @ 0x11512a0] Codec for stream 0 does not use global headers but container format requires global headers
  
  [mp4 @ 0x11512a0] Codec for stream 0 does not use global headers but container format requires global headers
  
  [mp4 @ 0x11512a0] Codec for stream 0 does not use global headers but container format requires global headers