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• FFMPEG and Mencoder building screenshot returns 0 size images

  12 avril 2014, par Genus

  I have a script and it used to work fine but suddenly it stopped working and giving me zero size images as screenshot after video convert.

  here is the command for video screenshot.

  $cmd = $GLOBALS["paths"]["ffmpeg"]." -y -i ".$file." -f mjpeg -r 1 -ss ".$time." -vframes 1 -an ".$tmpdir."/00000001.jpg 2>&1";
  
      exec($cmd,$results);

  Debug :

  -----------------------------------------------------
  
  
  
  ------------mencoder_and_fmpeg.php SCREENSHOT -------
  
  
  
  -----------------------------------------------------
  
  
  
    COMMAND: ffmpeg -y -i /home/TESTING/public_html/vid/6d/ad/29/6dad2946a2ba102.flv -f mjpeg -r 1 -ss 14.48 -vframes 1 -an /home/TESTING/public_html/scr/42/3a/92/00000001.jpg 2>&1
  
  
  
    FFmpeg version SVN-r16244, Copyright (c) 2000-2008 Fabrice Bellard, et al.
  
  
  
    configuration: --disable-mmx --enable-shared --enable-libvorbis --enable-gpl --enable-swscale --enable-pthreads --disable-static --disable-demuxer=v4l --disable-demuxer=v4l2 --enable-libtheora --enable-gpl --enable-libspeex --enable-libmp3lame --enable-libfaac --enable-libfaad --enable-libfaadbin --enable-libamr-nb --enable-libamr-wb --enable-nonfree --enable-libxvid
  
    libavutil     49.12. 0 / 49.12. 0
  
    libavcodec    52. 7. 0 / 52.108. 0
  
    libavformat   52.23. 1 / 52.92. 0
  
    libavdevice   52. 1. 0 / 52. 2. 3
  
    libswscale     0. 6. 1 /  0.12. 0
  
  
  
    built on Apr  9 2011 22:48:41, gcc: 4.1.2 20080704 (Red Hat 4.1.2-50)
  
    built by Admin-Ahead Server Technologies FFmpeg installer v5.0.6b
  
    Seems stream 0 codec frame rate differs from container frame rate: 1000.00 (1000/1) -> 10.92 (131/12)
  
    Stream mapping:
  
    Stream #0.0 -> #0.0
  
  
  
    Press [q] to stop encoding
  
    ffmpeg: symbol lookup error: ffmpeg: undefined symbol: frame_hook_process

• why type casting on non-pointer struct give syntax error

  31 mars 2016, par Sany Liew

  I am using Visual C++ express 2008 try to compile code similar to below :

  no problem

  {
  
    ...
  
    AVRational test = {1, 1000};
  
    ...
  
  }

  but has problem when it is as below :

  {
  
    ...
  
    AVRational test = (AVRational){1, 1000};
  
    ...
  
  }

  gave errors :

  1>..\..\..\projects\test\xyz.cpp(1139) : error C2059: syntax error : '{'
  
  1>..\..\..\projects\test\xyz.cpp(1139) : error C2143: syntax error : missing   ';' before '{'
  
  1>..\..\..\projects\test\xyz.cpp(1139) : error C2143: syntax error : missing ';' before '}'

  where AVRational (ffmpeg.org library) is defined as :

  typedef struct AVRational{
  
      int num; ///< numerator
  
      int den; ///< denominator
  
  } AVRational;

  FFmpeg come with some pre-define value such as

  #define AV_TIME_BASE_Q (AVRational){1, AV_TIME_BASE}

  which is used as below

  av_rescale_q(seek_target, AV_TIME_BASE_Q, pFormatCtx->streams[stream_index]->time_base);

  will failed to compile on Visual C++ express 2008

  It seem like the same code will be compiled with no error/warning on gcc compiler. Why I get this error on VC++ ? Is it a C/C++ standard way to do casting on struct value ? Anyway I can avoid this error while still able to use the defined AV_TIME_BASE_Q ?

• X264 : How to access NAL units from encoder ?

  18 avril 2014, par user1884325

  When I call

  frame_size = x264_encoder_encode(encoder, &nals, &i_nals, &pic_in, &pic_out);

  and subsequently write each NAL to a file like this :

       if (frame_size >= 0)
  
       {
  
          int i;
  
          int j;
  
  
  
          for (i = 0; i < i_nals; i++)
  
          {
  
             printf("******************* NAL %d (%d bytes) *******************\n", i, nals[i].i_payload);
  
             fwrite(&(nals[i].p_payload[0]), 1, nals[i].i_payload, fid);
  
          }
  
       }

  then I get this

  

  My questions are :

  1) Is it normal that there’s readable parameters in the beginning of the file ?

  2) How do I configure the X264 encoder so that the encoder returns frames that I can send via UDP without the packet getting fragmented (size must be below 1390 or somewhere around that).

  3) With the x264.exe I pass in these options :

  "--threads 1 --profile baseline --level 3.2 --preset ultrafast --bframes 0 --force-cfr --no-mbtree --sync-lookahead 0 --rc-lookahead 0 --keyint 1000 --intra-refresh" 

  How do I map those to the settings in the X264 parameters structure ? (x264_param_t)

  4) I have been told that the x264 static library doesn’t support bitmap input to the encoder and that I have to use libswscale for conversion of the 24bit RGB input bitmap to YUV2. The encoder, supposedly, only takes YUV2 as input ? Is this true ? If so, how do I build libswscale for the x264 static library ?