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• Issue while opening a .mp4 file - CPU shoots up 100%

  16 juillet 2014, par AnilJ

  I am using IMediaWriter, to write out about 20 video frames into an independent .mp4 file and creating a new writer to write a new file. This is a logic (not so efficient one), I’ve used to chunk the web-cam feed into chunks. I am able to successfully able to create multiple .mp4 video files and when opened then in a VLC player, they can be played back.

  However, when I try to open one of the chunked file into a new IContainer object (see below code snippet), my program :

  • Gets stuck at the container.open() call ( see * below), and the CPU
    utilization shoots above 100%.
  • Sometimes it throws an error "moov atom not found", and hence can not open the file.

  In both the cases, my program does not work.

  <code snippet="snippet">
  
          String file = BASE_PATH + File.separator + "output" + File.separator + "output.mp4";  // This is one of the chunk.
  
          IContainer container = IContainer.make();
  
          FileChannel channel = null;
  
  
  
          try {
  
              @SuppressWarnings("resource")
  
              RandomAccessFile inFile = new RandomAccessFile(chunkFile, "r");
  
              channel = inFile.getChannel();
  
          } catch (FileNotFoundException e) {
  
              e.printStackTrace();
  
          }
  
  
  
          // Open up the container
  
  ***        int retval = container.open(channel, IContainer.Type.READ, null);
  
          if (retval &lt; 0) {
  
              // This little trick converts the non friendly integer return value into 
  
              // a slightly more friendly object to get a human-readable error name
  
              IError error = IError.make(retval);
  
              throw new IllegalArgumentException("could not open file: " + mInputFileChannel + "; Error: " + error.getDescription());
  
          }
  
  <code snippet="snippet">
  
  

  Subsequently, I ran the AtomicParsley tool to dump the file content, and it prints following. I am not aware of video file internals and seeking help to know the issue here and potential solution.

  Atom ftyp @ 0 of size: 28, ends @ 28
  
  Atom free @ 28 of size: 8, ends @ 36
  
  Atom mdat @ 36 of size: 45175, ends @ 45211
  
  Atom moov @ 45211 of size: 1052, ends @ 46263
  
       Atom mvhd @ 45219 of size: 108, ends @ 45327
  
       Atom trak @ 45327 of size: 839, ends @ 46166
  
           Atom tkhd @ 45335 of size: 92, ends @ 45427
  
           Atom edts @ 45427 of size: 36, ends @ 45463
  
               Atom elst @ 45435 of size: 28, ends @ 45463
  
           Atom mdia @ 45463 of size: 703, ends @ 46166
  
               Atom mdhd @ 45471 of size: 32, ends @ 45503
  
               Atom hdlr @ 45503 of size: 45, ends @ 45548
  
               Atom minf @ 45548 of size: 618, ends @ 46166
  
                   Atom vmhd @ 45556 of size: 20, ends @ 45576
  
                   Atom dinf @ 45576 of size: 36, ends @ 45612
  
                       Atom dref @ 45584 of size: 28, ends @ 45612
  
                           Atom url  @ 45600 of size: 12, ends @ 45612
  
                   Atom stbl @ 45612 of size: 554, ends @ 46166
  
                       Atom stsd @ 45620 of size: 198, ends @ 45818
  
                           Atom mp4v @ 45636 of size: 182, ends @ 45818
  
                               Atom esds @ 45722 of size: 96, ends @ 45818
  
                       Atom stts @ 45818 of size: 176, ends @ 45994
  
                       Atom stss @ 45994 of size: 24, ends @ 46018
  
                       Atom stsc @ 46018 of size: 28, ends @ 46046
  
                       Atom stsz @ 46046 of size: 100, ends @ 46146
  
                       Atom stco @ 46146 of size: 20, ends @ 46166
  
       Atom udta @ 46166 of size: 97, ends @ 46263
  
           Atom meta @ 46174 of size: 89, ends @ 46263
  
               Atom hdlr @ 46186 of size: 33, ends @ 46219
  
               Atom ilst @ 46219 of size: 44, ends @ 46263
  
                   Atom ©too @ 46227 of size: 36, ends @ 46263
  
                       Atom data @ 46235 of size: 28, ends @ 46263
  
  ------------------------------------------------------
  
  Total size: 46263 bytes; 31 atoms total. AtomicParsley from svn built on Jul 15 2014 (utf8)
  
  Media data: 45175 bytes; 1088 bytes all other atoms (2.352% atom overhead).
  
  Total free atom space: 8 bytes; 0.017% waste.
  
  ------------------------------------------------------

  I am not sure if there is anything wrong with the file itself. Can you please help me understand this ?

• Problem with FFMPEG and PHP

  10 septembre 2014, par ziritrion

  I know this isn’t exactly a programming question per se, but rather a settings question, but still :

  I’m trying to convert video with FFMPEG with a PHP script, following this tutorial :

  http://vexxhost.com/blog/2007/05/20/how-to-convertencode-files-to-flv-using-ffmpeg-php/

  FFMPEG works perfectly and I’ve used it from the command line a number of times. PHP also seems to work fine. I’ve also installed ffmpeg-php and it seems to be loading file.

  The problem lies when I try to do the following in PHP :

  $srcFile = "p1.avi" ;

  $ffmpegObj = new ffmpeg_movie($srcFile) ;

  No matter what, PHP will return this :

  Warning : can’t open movie file p1.avi in /var/www/converter.php on line xx

  Obviously, whatever call I do afterwards with $ffmpegObj will throw a fatal error. I’m absolutely stuck and extensive googling hasn’t helped much.

  If you must know, I’m using Ubuntu 9.04 with the default LAMP server packages as well as php5-ffmpeg, and I’ve compiled ffmpeg following a tutorial I found on Ubuntuforums (I’d link to it but stackoverflow won’t let me)

  Thanks !

• ffmpeg include issue - some functions are missing

  9 septembre 2014, par Thomas

  I try to follow and adapt this example to convert a video thanks to FFMPEG but some function seems to be missing like :

  int avcodec_open ( AVCodecContext * avctx, AVCodec * codec)     

  When I go in the doc to see where it come from, I find it in the file libavcodec/avcodec.h which is included in my program #include "libavcodec/avcodec.h" (in the top of my .h file).

  Given this, I don’t understand why Qt throw me this error :

  ../../Dev/Joker/libs/PhVideo/PhVideoEncoder.cpp:360:6: error: use of undeclared identifier 'avcodec_open'
  
      if (avcodec_open(c, codec) < 0) {