Android Open Source - spydroid-ipcamera A M R N B Packetizer

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License

The source code is released under:

GNU General Public License

Java Source Code

/*
 * Copyright (C) 2011-2014 GUIGUI Simon, fyhertz@gmail.com
 * /*ww w.  j  av a  2 s  .  c  om*/
 * This file is part of libstreaming (https://github.com/fyhertz/libstreaming)
 * 
 * Spydroid is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This source code is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this source code; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package net.majorkernelpanic.streaming.rtp;

import java.io.IOException;

import android.util.Log;

/**
 * 
 *   RFC 3267.
 *   
 *   AMR Streaming over RTP.
 *   
 *   Must be fed with an InputStream containing raw amr nb
 *   Stream must begin with a 6 bytes long header: "#!AMR\n", it will be skipped
 *   
 */
public class AMRNBPacketizer extends AbstractPacketizer implements Runnable {

  public final static String TAG = "AMRNBPacketizer";

  private final int AMR_HEADER_LENGTH = 6; // "#!AMR\n"
  private static final int AMR_FRAME_HEADER_LENGTH = 1; // Each frame has a short header
  private static final int[] sFrameBits = {95, 103, 118, 134, 148, 159, 204, 244};
  private int samplingRate = 8000;

  private Thread t;

  public AMRNBPacketizer() {
    super();
    socket.setClockFrequency(samplingRate);
  }

  public void start() {
    if (t==null) {
      t = new Thread(this);
      t.start();
    }
  }

  public void stop() {
    if (t != null) {
      try {
        is.close();
      } catch (IOException ignore) {}
      t.interrupt();
      try {
        t.join();
      } catch (InterruptedException e) {}
      t = null;
    }
  }

  public void run() {

    int frameLength, frameType;
    long now = System.nanoTime(), oldtime = now;
    byte[] header = new byte[AMR_HEADER_LENGTH];

    try {

      // Skip raw amr header
      fill(header,0,AMR_HEADER_LENGTH);
      
      if (header[5] != '\n') {
        Log.e(TAG,"Bad header ! AMR not correcty supported by the phone !");
        return;
      }

      while (!Thread.interrupted()) {

        buffer = socket.requestBuffer();
        buffer[rtphl] = (byte) 0xF0;
        
        // First we read the frame header
        fill(buffer, rtphl+1,AMR_FRAME_HEADER_LENGTH);

        // Then we calculate the frame payload length
        frameType = (Math.abs(buffer[rtphl + 1]) >> 3) & 0x0f;
        frameLength = (sFrameBits[frameType]+7)/8;

        // And we read the payload
        fill(buffer, rtphl+2,frameLength);

        //Log.d(TAG,"Frame length: "+frameLength+" frameType: "+frameType);

        // RFC 3267 Page 14: "For AMR, the sampling frequency is 8 kHz"
        // FIXME: Is this really always the case ??
        ts += 160L*1000000000L/samplingRate; //stats.average();
        socket.updateTimestamp(ts);
        socket.markNextPacket();

        //Log.d(TAG,"expected: "+ expected + " measured: "+measured);
        
        send(rtphl+1+AMR_FRAME_HEADER_LENGTH+frameLength);
        
      }

    } catch (IOException e) { 
    } catch (InterruptedException e) {}

    Log.d(TAG,"AMR packetizer stopped !");

  }

  private int fill(byte[] buffer, int offset,int length) throws IOException {
    int sum = 0, len;
    while (sum<length) {
      len = is.read(buffer, offset+sum, length-sum);
      if (len<0) {
        throw new IOException("End of stream");
      }
      else sum+=len;
    }
    return sum;
  }


}

Java Source Code List

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