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• libav :0: : cabac decode of qscale diff failed at 4 26 ? While UDP Streaming in Gstreamer

  28 juin 2016, par Prasanth Kumar Arisetti

  I would like to stream the webcam data over UDP in mpegts format.

  At Sending End: :

  gst-launch-1.0 -v v4l2src device=/dev/video1 ! videoconvert ! video/x-raw,width=720,height=576,framerate=25/1,format=I420 ! videoparse width=720 height=576 framerate=25/1 ! x264enc bitrate=2048 ref=4 key-int-max=20 byte-stream=true tune=zerolatency speed-preset=3 sliced-threads=true threads=4  ! video/x-h264,stream-format=byte-stream,profile=main ! queue ! mpegtsmux ! rtpmp2tpay ! udpsink host=192.168.2.149 port=8888 sync=true async=false qos=true qos-dscp=46

  At Receiving End: :

  GST_DEBUG=4 gst-launch-1.0 -v udpsrc port=8888 caps=application/x-rtp,media=video,encoding-name=MP2T buffer-size=524288 ! rtpmp2tdepay ! tsdemux name=demuxer  demuxer. !  queue max-size-buffers=0 max-size-time=0 ! h264parse ! avdec_h264 ! videoconvert ! xvimagesink qos=true sync=true async=false 

  For few seconds, video is coming good, but after that it is getting disturbed, and not at all coming, struck at single frame.

  And when i used GST_DEBUG=4, i observed below error :

  0:00.000000000, position 0:00:10.397114020, duration 99:99:99.999999999
  
  0:00:10.396195300   536 0x7f1328001300 ERROR                  libav :0:: cabac decode of qscale diff failed at 4 26
  
  0:00:10.396212221   536 0x7f1328001300 ERROR                  libav :0:: error while decoding MB 4 26, bytestream -1
  
  0:00:10.396255836   536       0xe03320 INFO                   libav :0:: concealing 1215 DC, 1215 AC, 1215 MV errors

  But, if I stream the Data to localhost, then it is perfectly working.

  After setting cabac=false on x264enc,

  0:00.000000000, position 0:00:14.796602703, duration 99:99:99.999999999
  
  0:00:15.020440888 15449 0x7f69dc4fe2c0 ERROR                  libav :0:: out of range intra chroma pred mode at 18 14
  
  0:00:15.020464168 15449 0x7f69dc4fe2c0 ERROR                  libav :0:: error while decoding MB 18 14
  
  0:00:15.020694828 15449      0x2513320 INFO                   libav :0:: concealing 1215 DC, 1215 AC, 1215 MV errors

  What is the problem here ? is this because of network bandwidth or any other else ? And how to solve this problem ?

• Streaming FFMPEG RTSP in C#

  1er mars 2015, par Andrew Simpson

  I wish to stream an RTSP feed from my camera through my C# client app and eventually recieve it on my server.

  To test it I decided to stream it through my client and then recieve the jpeg frames from it as well.

  I 1st tested my command line arguments in a DOS window.

  It worked in that it stream to an output file without incident.

  So, now I ported it over to my C# app and used the Process Class.

  This is the code :

     Task.Run(() =>
  
      {
  
          try
  
          {
  
              process.Start();
  
              byte[] buffer = new byte[200000];
  
              baseStream = process.StandardOutput.BaseStream as FileStream;
  
              bool gotHeader = false;
  
              bool imgFound = false;
  
              int counter = 0;
  
              while (true)
  
              {
  
                  byte bit1 = (byte)baseStream.ReadByte();
  
                  buffer[counter] = bit1;
  
                  if (bit1 == 217 && gotHeader)
  
                  {
  
                      if (buffer[counter - 1] == 255)
  
                      {
  
                          byte[] jpeg = new byte[counter];
  
                          Buffer.BlockCopy(buffer, 0, jpeg, 0, counter);
  
                          using (MemoryStream ms = new MemoryStream(jpeg))
  
                          {
  
                              pictureBox1.Image = Image.FromStream(ms);
  
                              ms.Close();
  
                          }
  
                          imgFound = true;
  
                      }
  
                  }
  
                  else if (bit1 == 216)
  
                  {
  
                      if (buffer[counter - 1] == 255)
  
                      {
  
                          gotHeader = true;
  
                      }
  
                  }
  
                  if (imgFound)
  
                  {
  
                      counter = 0;
  
                      buffer = new byte[200000];
  
                      imgFound = false;
  
                      gotHeader = false;
  
                  }
  
                  else
  
                  {
  
                      counter++;
  
                  }
  
              }
  
          }
  
          catch (Exception ex2)
  
          {
  
              //log error here
  
          }
  
      });

  But I do not get any images I just get the byte value of 255 at this line :

  buffer[counter] = bit1;

  So.. what am I doing wrong please ?

  Thanks

• Convert wma stream to mp3 stream with C# and ffmpeg

  24 septembre 2012, par user1363468

  Is it possible to convert a wma stream to an mp3 stream real time ?

  I have tried doing something like this but not having any luck :

      WebRequest request = WebRequest.Create(wmaUrl);
  
      HttpWebResponse response = (HttpWebResponse)request.GetResponse();
  
      int block = 32768;
  
      byte[] buffer = new byte[block];
  
  
  
      Process p = new Process();
  
      p.StartInfo.UseShellExecute = false;
  
      p.StartInfo.ErrorDialog = false;
  
      p.StartInfo.RedirectStandardInput = true;
  
      p.StartInfo.RedirectStandardOutput = true;
  
      p.StartInfo.RedirectStandardError = true;
  
      p.StartInfo.FileName = "c:\\ffmpeg.exe";
  
      p.StartInfo.Arguments = "-i - -y -vn -acodec libspeex -ac 1 -ar 16000 -f mp3 ";
  
  
  
      StringBuilder output = new StringBuilder();
  
  
  
      p.OutputDataReceived += (sender, e) =>
  
      {
  
        if (e.Data != null)
  
        {
  
          output.AppendLine(e.Data);
  
          //eventually replace this with response.write code for a web request
  
        }
  
      };
  
  
  
      p.Start();
  
      StreamWriter ffmpegInput = p.StandardInput;
  
  
  
      p.BeginOutputReadLine();
  
  
  
      using (Stream dataStream = response.GetResponseStream())
  
      {
  
         int read = dataStream.Read(buffer, 0, block);
  
  
  
         while (read > 0)
  
         {
  
            ffmpegInput.Write(buffer);
  
            ffmpegInput.Flush();
  
            read = dataStream.Read(buffer, 0, block);
  
         }
  
      }
  
  
  
      ffmpegInput.Close();
  
  
  
      var getErrors = p.StandardError.ReadToEnd();

  Just wondering if what I am trying to do is even possible (Convert byte blocks of wma to byte blocks of mp3). Open to any other possible C# solutions if they exist.

  Thanks