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• Segmentation Fault error when trying to compare two videos with pHash library and its ruby bindings

  10 juillet 2014, par anado1771

  I have set up my system with the latest ffmpeg and pHash libraries (ffmpeg-2.2.1 and pHash-0.9.6) as well as the pHash ruby gem (https://github.com/toy/pHash).

  I am using ruby and attempting to compare two video files like this :

  require 'phash/video'
  
  
  
  video1 = Phash::Video.new('video1.mp4')
  
  video2 = Phash::Video.new('video2.mp4')
  
  
  
  video1 % video2

  Executing this script results in a Segmentation fault :

  ..../gems/pHash-1.1.4/lib/phash/video.rb:20: [BUG] Segmentation fault
  
  ruby 1.9.3p545 (2014-02-24 revision 45159) [x86_64-darwin13.1.0]
  
  
  
  -- Control frame information -----------------------------------------------
  
  c:0008 p:---- s:0029 b:0029 l:000028 d:000028 CFUNC  :ph_dct_videohash
  
  c:0007 p:0042 s:0024 b:0024 l:000023 d:000023 METHOD .../gems/pHash-1.1.4/lib/phash/video.rb:20
  
  c:0006 p:0038 s:0017 b:0017 l:000016 d:000016 METHOD .../gems/pHash-1.1.4/lib/phash.rb:43
  
  c:0005 p:0025 s:0014 b:0014 l:000013 d:000013 METHOD .../gems/pHash-1.1.4/lib/phash.rb:39
  
  c:0004 p:0011 s:0011 b:0011 l:000010 d:000010 METHOD .../gems/pHash-1.1.4/lib/phash.rb:48
  
  c:0003 p:0050 s:0006 b:0006 l:000128 d:0011b8 EVAL   video_test_phash.rb:3
  
  c:0002 p:---- s:0004 b:0004 l:000003 d:000003 FINISH
  
  c:0001 p:0000 s:0002 b:0002 l:000128 d:000128 TOP   
  
  
  
  -- Ruby level backtrace information ----------------------------------------
  
  video_test_phash.rb:3:in `<main>'
  
  .../gems/pHash-1.1.4/lib/phash.rb:48:in `similarity'
  
  .../gems/pHash-1.1.4/lib/phash.rb:39:in `phash'
  
  .../gems/pHash-1.1.4/lib/phash.rb:43:in `compute_phash'
  
  .../gems/pHash-1.1.4/lib/phash/video.rb:20:in `video_hash'
  
  .../gems/pHash-1.1.4/lib/phash/video.rb:20:in `ph_dct_videohash'
  
  
  
  ...
  
  
  
  Abort trap: 6
  
  </main>

  It appears that the crash happens in the ph_dct_videohash function which is part of the pHash library. The function is in file pHash.cpp. I am copying it here in case it would make sense to someone :

  ulong64* ph_dct_videohash(const char *filename, int &Length){
  
  
  
      CImgList *keyframes = ph_getKeyFramesFromVideo(filename);
  
      if (keyframes == NULL)
  
      return NULL;
  
  
  
      Length = keyframes->size();
  
  
  
      ulong64 *hash = (ulong64*)malloc(sizeof(ulong64)*Length);
  
      CImg<float> *C = ph_dct_matrix(32);
  
      CImg<float> Ctransp = C->get_transpose();
  
      CImg<float> dctImage;
  
      CImg<float> subsec;
  
      CImg currentframe;
  
  
  
      for (unsigned int i=0;i &lt; keyframes->size(); i++){
  
      currentframe = keyframes->at(i);
  
      currentframe.blur(1.0);
  
      dctImage = (*C)*(currentframe)*Ctransp;
  
      subsec = dctImage.crop(1,1,8,8).unroll('x');
  
      float med = subsec.median();
  
      hash[i] =     0x0000000000000000;
  
      ulong64 one = 0x0000000000000001;
  
      for (int j=0;j&lt;64;j++){
  
          if (subsec(j) > med)
  
          hash[i] |= one;
  
          one = one &lt;&lt; 1;
  
      }
  
      }
  
  
  
      keyframes->clear();
  
      delete keyframes;
  
      keyframes = NULL;
  
      delete C;
  
      C = NULL;
  
      return hash;
  
  }
  
  </float></float></float></float>

  Any help is very much appreciated !

• ffmpeg static build produces huge files

  3 mai 2014, par user3581244

  I’ve recently managed to get a static build of ffmpeg installed on an EC2 instance :

  http://ffmpeg.gusari.org/static/64bit/ffmpeg.static.64bit.2014-03-05.tar.gz

  But when I perform this command on a video file :

  ffmpeg -ss 00:00:00 -i VIDEO0031.mp4 -r 8 -vframes 32 -vbsf remove_extra -an -vcodec pam -f rawvideo -y test_002.pam

  It produces a file that is 190MB which is huge and then it messes up the other commands I use to convert it into a gif file.

  Does anyone know if this is just an issue with using a static build ? I didn’t experience this issue using an older ffmpeg install ( v0.6 I believe ) so am tempted to go back to the old install but I also need to have ffprobe installed so am worried this would cause issues.

  A bit of a random question but I thought it was worth asking just in case someone had come across a similar thing.

  Thanks !

• Command work, but have a error when used by sh [on hold]

  6 mai 2014, par DrakaSAN

  I have this script :

  extract.sh :

  ffmpeg –i $1 –ss $2 –t $3 –c:v copy –c:a copy $4

  If I type

  ffmpeg –i full.mp4 –ss 114 –t 30 –c:v copy –c:a copy out.mp4

  All go well. But if I try

  sh extract.sh full.mp4 114 30 out.mp4

  I get :

  ffmpeg version 2.1 Copyright (c) 2000-2013 the FFmpeg developers
  
    built on May  5 2014 11:41:48 with gcc 4.6 (Ubuntu/Linaro 4.6.3-1ubuntu5)
  
    configuration: --enable-gpl
  
    libavutil      52. 48.100 / 52. 48.100
  
    libavcodec     55. 39.100 / 55. 39.100
  
    libavformat    55. 19.104 / 55. 19.104
  
    libavdevice    55.  5.100 / 55.  5.100
  
    libavfilter     3. 90.100 /  3. 90.100
  
    libswscale      2.  5.101 /  2.  5.101
  
    libswresample   0. 17.104 /  0. 17.104
  
    libpostproc    52.  3.100 / 52.  3.100
  
  [NULL @ 0x2a20b00] Unable to find a suitable output format for '–i'
  
  –i: Invalid argument

  What does sh do to the argument to make it unreadable in the script ?

  EDIT :

  user@domain:~/test$ sh extract.sh cdr.mp4 0 7 generique.mp4
  
  ffmpeg –i cdr.mp4 –ss 0 –t 7 –c:v copy –c:a copy generique.mp4