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• Decoding H.264 stream from dvr

  17 octobre 2013, par Andrew S

  I have a security DVR that uses h264 streams. I have been trying to get this to work with zoneminder. I have successfully logged into the dvr and recieved some form of data streams. The data stream is dumped to a fifo/pipe, and then zoneminder uses ffmpeg to read this in.

  Note : i know very very little about h.264 streams. just enough to be stupid.

  The video only updates about every 15 seconds in ZM. I can dump the stream to a file with ffmpeg or avconv (avconv -i /tmp/mypipe cam.mp4) but it is still not right. However, the file created by avconv is WAY WAY better than the one created by ffmpeg.

  I've included a link to the wireshark dump (I did change the PW and login info, etc...). From the data, It appears that the dvr is adding a header to the h264 data streams. I understand that the h264 stream starts with a (0x00 00 01 67) or (0x00 00 01 61). Here is an example of the header plus start of stream :

  0x33, 0x30, 0x64, 0x63, 0x48, 0x32, 0x36, 0x34, 
  
  0x3f, 0x55, 0x00, 0x00, 0x08, 0x00, 0x20, 0x00, 
  
  0xa2, 0x7a, 0xea, 0xdc, 0xcf, 0x08, 0x00, 0x00, 
  
  0x0d, 0x0a, 0x11, 0x07, 0x13, 0x20, 0x00, 0x00, 
  
  0x00, 0x00, 0x00, 0x01, 0x67, 0x42, 0xe0, 0x14, 
  
  0xdb, 0x05, 0x87, 0xc4, 0x00, 0x00, 0x00, 0x01, 
  
  0x68, 0xce, 0x30, 0xa4, 0x80, 0x00, 0x00, 0x00, 
  
  0x01, 0x06, 0xe5, 0x01, 0x51, 0x80, 0x00, 0x00, 
  
  0x00, 0x01, 0x65, 0xb8, 0x00, 0x01, 0xa8, 0xac,

  I can see that there are a few frame indicators in this message. The DVR's header appears to be 32 bytes long in this case, and in some other messages in the dump, it appears to be 24 bytes long. I am striping the header off before I dump the stream to the pipe. (I have verified the output doesn't include the dvr's headers in any way.

  What I would like help with is determining what I should be sending to the pipe. should I start with the first h.264 key ? Is there something out of order ? I'm very surprised that ffmpeg is only getting 15 second updates, but avconv is much better (lots of dropped frames, and playback is "sped up".

  using ffmpeg to read the pipe produces a file that shows it's codec as : H264 - MPEG-4 AVC (part 10) (avc1) with a Decoded format : Planar 4:2:0 YUV using vlc.

  Appreciate any help you can provide !

  Wireshark h264 dump

  edit : on Ubuntu 13.04
  ffmpeg version : 6:0.8.6-1ubuntu2
  avconv 0.8.6-6:0.8.6-1ubuntu2

• Anomalie #3069 (Nouveau) : autorisations

  2 octobre 2013, par chan kalan

  relaté dans le carnet ici http://contrib.spip.net/Autorisations-Dans-Spip
  -> On veut permettre aux administrateurs restreints de modifier le login et mot de passe des visiteurs -> voir la fonction autoriser_auteur_modifier_dist - http://core.spip.org/projects/spip/repository/entry/branches/spip-3-stable/ecrire/inc/autoriser.php#L739 et principalement à cette partie du code ligne 763 :
  

  elseif ($opt[’statut’] == ’0minirezo’ OR $opt[’restreintes’])
                          return false ;
  

  surchargée par :

  elseif ($opt[’statut’] == ’0minirezo’)
                          return false ;

  
  Pourquoi le fait de retirer
  

  OR $opt[’restreintes’]
  

  
  permet-il de modifier le login et mot de passe ?

• Playing audio file using libavcodec and libao

  21 août 2013, par sarah john

  Myself trying to play an audio file using libavcodec in qt5 .While trying to play i am unable to play the the file.
  while decoding the file using av_read_frame()
  audioStream->index=0
  and packet.stream_index is some higher nos .so avcodec_decode_audio4() is not getting executed.Why is it so ?
  I am getting output as
  My output

  ---

  File Opend

  Input #0, ogg, from '/home/tel/Downloads/desktop-login.ogg':
  
  Duration: 00:00:07.72, start: 0.000000, bitrate: 108 kb/s
  
  Stream #0:0: Audio: vorbis, 44100 Hz, stereo, fltp, 112 kb/s
  
  audioStream 0x88b3f20
  
  Stream id: 0
  
  Codec ptr: 0x88b4100
  
  Codec Opened
  
  DRIVER ID 1
  
  Sample format 3
  
  Sample format:AV_SAMPLE_FMT_FLT 32
  
  Sample format channels 0
  
  Sample format rate 0
  
  Sample format  4
  
  buffersize  192008

  This is my program. My output is also given below.Please help me in solving this.

  for(i=0; i < container->nb_streams; i++){
  
  
  
      if(container->streams[i]->codec->codec_type==AVMEDIA_TYPE_AUDIO){
  
           stream_id=i;
  
           audioStream=container->streams[i];
  
  
  
           qWarning() <<"audioStream"<streams[stream_id]->codec;
  
  qWarning() <<"Codec ptr:"<< ctx;
  
  AVCodec *codec=avcodec_find_decoder(ctx->codec_id);
  
  if(codec==NULL){
  
          die("cannot find codec!");
  
  }
  
  
  
  if(avcodec_open2(ctx,codec,NULL)<0){
  
          die("Codec cannot be opended!");
  
  }
  
  else
  
          qWarning()<<"Codec Opened";
  
  
  
  
  
          ao_initialize();
  
          driver = ao_default_driver_id();
  
          qWarning()<<"DRIVER ID" <sample_fmt;
  
          qWarning()<<"Sample format"<channels;
  
     qWarning()<<"Sample format channels"<sample_rate;
  
    qWarning()<<"Sample format rate"<codec;
  
    while(av_read_frame(container,&packet)>=0)
  
    {
  
  
  
          if(packet.stream_index==audioStream->index){
  
          len=avcodec_decode_audio4(ctx,frame,&frameFinished,&packet);
  
          qWarning()<<"Enterd if loop";
  
  
  
          if(frameFinished){
  
              qWarning()<<"PLAYING";
  
              ao_play(audio_device, (char*)frame->extended_data[0],frame->linesize[0] );
  
          }
  
    }