RTPAudioFormat.java

/*
 * RTPAudioFormat.java
 *
 * Mobicents Media Gateway
 *
 * The source code contained in this file is in in the public domain.
 * It can be used in any project or product without prior permission,
 * license or royalty payments. There is  NO WARRANTY OF ANY KIND,
 * EXPRESS, IMPLIED OR STATUTORY, INCLUDING, WITHOUT LIMITATION,
 * THE IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE,
 * AND DATA ACCURACY.  We do not warrant or make any representations
 * regarding the use of the software or the  results thereof, including
 * but not limited to the correctness, accuracy, reliability or
 * usefulness of the software.
 */
package org.mobicents.media.server.impl.rtp.sdp;

import java.util.Collection;
import java.util.Vector;
import javax.sdp.Attribute;
import javax.sdp.SdpFactory;
import org.mobicents.media.format.AudioFormat;

/**
 * This represents the RTP Audio Format. The difference being RTPAudioFormat
 * also carries the pay-load. For example look at SDP <br/>
 * <p>
 * <blockquote>
 * 
 * <pre>
 * m=audio 8010 RTP/AVP 0 8 97 
 * a=rtpmap:0 PCMU/8000 
 * a=rtpmap:8 PCMA/8000
 * a=rtpmap:97 speex/8000 
 * a=ptime:20 	
 * </pre>
 * 
 * </blockquote>
 * </p>
 * 
 * <br/>
 * 
 * here pay-load is 0 for PCMU, 8 for PCMA and 97 for speex
 * 
 */
public class RTPAudioFormat extends AudioFormat implements RTPFormat {

    private int payloadType;
    private final static SdpFactory sdpFactory = SdpFactory.getInstance();

    /** Creates a new instance of RTPAudioFormat */
    public RTPAudioFormat(int payload, String encodingName) {
        super(encodingName);
        this.payloadType = payload;
    }

    public RTPAudioFormat(int payload, String encodingName, double sampleRate, int bits, int chans) {
        super(encodingName, sampleRate, bits, chans);
        this.payloadType = payload;
    }

    public RTPAudioFormat(int payload, String encodingName, double sampleRate, int bits, int chans, int endian, int signed) {
        super(encodingName, sampleRate, bits, chans, endian, signed);
        this.payloadType = payload;
    }

    public int getPayloadType() {
        return payloadType;
    }

    public void setPayloadType(int payload) {
        this.payloadType = payload;
    }

    private static int getBits(String enc) {
        if (enc.equals("pcm")) {
            return 8;
        } else if (enc.equals("gsm")) {
            return 8;
        } else if (enc.equals("dvi")) {
            return 4;
        } else {
            return 8;
        }
    }


    public static RTPAudioFormat parseFormat(String rtpmap) {
        String tokens[] = rtpmap.toLowerCase().split(" ");

        // split params
        int p = Integer.parseInt(tokens[0]);
        tokens = tokens[1].split("/");

        String encodingName = tokens[0];
        double clockRate = Double.parseDouble(tokens[1]);

        int chans = 1;
        if (tokens.length == 3) {
            chans = Integer.parseInt(tokens[2]);
        }

        if (encodingName.equals("pcmu")) {
            return new RTPAudioFormat(p, AudioFormat.ULAW, clockRate, 8, chans);
        } else if (encodingName.equals("pcma")) {
            return new RTPAudioFormat(p, AudioFormat.ALAW, clockRate, 8, chans);
        } else if (encodingName.equals("speex")) {
            return new RTPAudioFormat(p, AudioFormat.SPEEX, clockRate, AudioFormat.NOT_SPECIFIED, chans);
        } else if (encodingName.equals("telephone-event")) {
            return new RTPAudioFormat(p, "telephone-event", clockRate, AudioFormat.NOT_SPECIFIED, AudioFormat.NOT_SPECIFIED);
        } else if (encodingName.equals("g729")) {
            return new RTPAudioFormat(p, AudioFormat.G729, clockRate, AudioFormat.NOT_SPECIFIED, chans);
        } else if (encodingName.equals("gsm")) {
            return new RTPAudioFormat(p, AudioFormat.GSM, clockRate, AudioFormat.NOT_SPECIFIED, chans);
        } else if (encodingName.equals("l16")){
            return new RTPAudioFormat(p, AudioFormat.LINEAR, clockRate, 16, chans, 
                    AudioFormat.LITTLE_ENDIAN, AudioFormat.SIGNED);
        } else {
            return null;
        }
    }

    public Collection<Attribute> encode() {
        Vector<Attribute> list = new Vector();
        list.add(sdpFactory.createAttribute("rtpmap", toSdp()));
        if (getEncoding().equalsIgnoreCase("telephone-event")) {
            list.add(sdpFactory.createAttribute("fmtp", payloadType + " 0-15"));
        } else if (getEncoding().equalsIgnoreCase("g729")) {
            list.add(sdpFactory.createAttribute("fmtp", payloadType + " annex=b"));
        }
        return list;
    }

    public String toSdp() {
        String encName = this.getEncoding().toLowerCase();
        StringBuffer buff = new StringBuffer();
        buff.append(payloadType);
        buff.append(" ");

        if (encName.equals("alaw")) {
            buff.append("pcma");
        } else if (encName.equals("ulaw")) {
            buff.append("pcmu");
        } else if (encName.equals("linear")) {
            buff.append("l" + this.sampleSizeInBits);
        } else {
            buff.append(encName);
        } 
        
        double sr = getSampleRate();
        if (sr > 0) {
            buff.append("/");

            if ((sr - (int) sr) < 1E-6) {
                buff.append((int) sr);
            } else {
                buff.append(sr);
            }
        }
        if (getChannels() > 1) {
            buff.append("/" + getChannels());
        }

        return buff.toString();
    }
}