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• Transport SEI With Ffmpeg

  29 août 2016, par yuan tian

  I need to transport some data from drone through the help of Ffmpeg.The data includes frame data and some other parameters such as the timing roll/pitch/height/direction of the drone,and when I get the image of the frame,the corresponding parameters should be also pulled out,So I dicede to send these parameters as SEI.
  Then the questions coming,after sending sps pps,I send my own SEI packet，eg :

   if(pkt->size>10&&pkt->data[0] ==0
  
         &&pkt->data[1] ==0
  
         &&pkt->data[2] ==0
  
         &&pkt->data[3] ==1
  
         &&(pkt->data[4] == 103 || pkt->data[4] == 104)){
  
          i++;
  
      }
  
      AVPacket *newPacket = nullptr;
  
      // 0 0 0 1 6 8*16
  
      if(i == 2){
  
          i = 0;
  
          newPacket = (AVPacket *)av_malloc(sizeof(AVPacket));
  
          av_init_packet(newPacket);
  
          newPacket->data = new uint8_t[8];
  
          newPacket->data[0] = 0;
  
          newPacket->data[1] = 0;
  
          newPacket->data[2] = 0;
  
          newPacket->data[3] = 1;
  
          newPacket->data[4] = 6;
  
          newPacket->data[5] = 123;
  
          newPacket->data[6] = 134;
  
          newPacket->data[7] = 128;
  
          newPacket->size = 8;
  
      }
  
   av_write_frame(*it , pkt);
  
          av_free_packet(pkt);
  
          if(newPacket){
  
              av_write_frame(*it , newPacket);
  
              av_free_packet(newPacket);
  
          }

  But,At the receiving terminate,I only find the API:av_read_frame.The API just decode every complete frame from AVFormatContext.My SEI go nothing !
  Besides,I also trying to put my parameters in side_data or metadate of AVFrame,but after rtp tansporting,received AVFrame’s side_data and metadata is 0x00 again.
  Could someone give me some train of thought ?

• Extract audio from Transport Stream and preserve length

  15 décembre 2015, par yuiu

  I’m using ffmpeg to extract audio from MPEG Transport Stream file recorded by DVB-S card. The command :

  ffmpeg -i video.ts -vn audio.wav

  The source file seems to be corrupted. I noticed the corruption happens from time to time, especially for videos longer than 1 hour. I’ve got errors like these :

  [mp2 @ 0x1bb5500] Header missing
  
  Error while decoding stream #0:1
  
  [mpegts @ 0x17eaf40] Continuity check failed for pid 5261 expected 2 got 6

  The problem is that the resulting audio.wav is shorter than the source video (40m33s and 40m59s accordingly). I’m looking for the way to preserve the original length in the resulting audio file.

  I tried the recent ffmpeg under Windows and avconv under Ubuntu, output format was MP3 and WAV. For every case I’ve got the same results.

• Node Webkit-Designing Media Player support all media codec(format)

  14 décembre 2015, par Vish

  I am working on product which classify any kind of media into movies, tv shows, videos, audio and images. Node webkit with angularjs and node is its base. Now I am trying to bring local playback, which enabled this classified media to play inside this desktop app. Have done lot of research, following are feasible solution to me :

  1. Getting ffmpegsumo.dll with all codec support, hence html <audio></audio> and <video></video> able to play all this videos.
  2. All unsupported video or audio to be converted into supporting codec format and steam it to <audio></audio> and <video></video> tag.
  3. Use some third party plugin to support like WebCherima .

  Option 1 and 2 are not looking feasible to me. For option 1, we have compile Chromium 41.0.2272.76 or nw.js v0.12.3 to update ffmpegsumo.dll with more codec. On other side Option 2 looking difficult to get good performance. I have learn few limitation of third party plugins.
  Please provide some insight ? Thanks !