基本思想是访问 .mp3 文件并通过 RTP 流将其发送给其他想要播放该歌曲的客户端。
这是 RTPServer.java，我在网上找到并根据自己的喜好对其进行了修改。
package server;
import java.net.InetAddress;
import javax.media.rtp.*;
import javax.media.rtp.rtcp.*;
import javax.media.*;
import javax.media.protocol.*;
import javax.media.control.*;
public class RTPServer implements ControllerListener, Runnable {
private boolean realized = false;
private boolean configured = false;
private String ipAddress;
Processor p;
MediaLocator src;
public static void main (String[] args) {
RTPServer rtp = new RTPServer("192.168.1.101", "04 - Blue.mp3");
Thread t = new Thread(rtp);
t.start();
}
public RTPServer(String ip, String song) {
ipAddress = ip;
String srcFile = "Muzika\\" + song;
src = new MediaLocator("file:" + srcFile);
}
private void setTrackFormat(Processor p) {
// Get the tracks from the processor
TrackControl [] tracks = p.getTrackControls();
// Do we have atleast one track?
if (tracks == null || tracks.length < 1) {
System.out.println("Couldn't find tracks in processor");
System.exit(1);
}
// Set the output content descriptor to RAW_RTP
// This will limit the supported formats reported from
// Track.getSupportedFormats to only valid RTP formats.
ContentDescriptor cd = new ContentDescriptor(ContentDescriptor.RAW_RTP);
p.setContentDescriptor(cd);
Format supported[];
Format chosen;
boolean atLeastOneTrack = false;
// Program the tracks.
for (int i = 0; i < tracks.length; i++) {
Format format = tracks[i].getFormat();
System.out.println("Trenutni format je " +format.getEncoding());
if (tracks[i].isEnabled()) {
supported = tracks[i].getSupportedFormats();
for (int n = 0; n < supported.length; n++)
System.out.println("Supported format: " + supported[n]);
// We've set the output content to the RAW_RTP.
// So all the supported formats should work with RTP.
// We'll just pick the first one.
if (supported.length > 0) {
chosen = supported[0]; // this is where I tried changing formats
tracks[i].setFormat(chosen);
System.err.println("Track " + i + " is set to transmit as: " +chosen);
atLeastOneTrack = true;
} else
tracks[i].setEnabled(false);
} else
tracks[i].setEnabled(false);
}
}
private void transmit(Processor p) {
try {
DataSource output = p.getDataOutput();
PushBufferDataSource pbds = (PushBufferDataSource) output;
RTPManager rtpMgr = RTPManager.newInstance();
SessionAddress localAddr, destAddr;
SendStream sendStream;
int port = 42050;
SourceDescription srcDesList[];
localAddr = new SessionAddress( InetAddress.getLocalHost(), port);
InetAddress ipAddr = InetAddress.getByName(ipAddress);
destAddr = new SessionAddress( ipAddr, port);
rtpMgr.initialize(localAddr);
rtpMgr.addTarget(destAddr);
sendStream = rtpMgr.createSendStream(output, 0);
sendStream.start();
System.err.println( "Created RTP session: " + ipAddress + " " + port);
p.start();
} catch(Exception e) {
e.printStackTrace();
}
}
public synchronized void controllerUpdate(ControllerEvent evt) {
if (evt instanceof RealizeCompleteEvent) {
realized = true;
} else if (evt instanceof ConfigureCompleteEvent) {
configured = true;
} else if (evt instanceof EndOfMediaEvent) {
System.exit(0);
} else {
// System.out.println(evt.toString());
}
}
public void run() {
try {
p = Manager.createProcessor(src);
p.addControllerListener(this);
p.configure();
while (! configured) {
try {
Thread.currentThread().sleep(100L);;
} catch (InterruptedException e) {
// ignore
}
}
setTrackFormat(p);
p.setContentDescriptor(new ContentDescriptor(ContentDescriptor.RAW_RTP));
p.realize();
while (! realized) {
try {
Thread.currentThread().sleep(100L);;
} catch (InterruptedException e) {
// ignore
}
}
transmit(p);
} catch(Exception e) {
e.printStackTrace();
System.exit(1);
}
}
}
And here is receiving end, RTPClient:
package client;
import javax.media.*;
public class RTPClient implements ControllerListener, Runnable {
Player p;
MediaLocator src;
public static void main(String[] args) {
RTPClient rtp = new RTPClient("192.168.1.100");
Thread t = new Thread(rtp);
t.start();
}
public RTPClient(String ip) {
String srcUrl = "rtp://" + ip + ":42050/audio/1";
DataSink sink;
src = new MediaLocator(srcUrl);
}
public void run() {
try {
p = Manager.createPlayer(src);
p.addControllerListener(this);
p.start();
} catch(Exception e) {
e.printStackTrace();
System.exit(1);
}
}
public synchronized void controllerUpdate(ControllerEvent evt) {
if (evt instanceof EndOfMediaEvent) {
System.exit(0);
} else {
System.out.println(evt.toString());
}
}
}
I figured, it successfully sends the whatever file I choose, but when I send .mp3, Client won't play it. I get:
RTP Handler internal error:
javax.media.ControllerErrorEvent[source=com.sun.media.content.unknown.Handler@9ed927,message=Internal
module com.sun.media.BasicRendererModule@1386000: failed to handle a data
format change!]
Interesting thing is, .wav is sent perfectly. So my guess was is the format set prior to sending. And I tried changing format to some other supported format, but then I get bunch of other errors.
Failed to build a graph for the given custom options.
Failed to realize: com.sun.media.ProcessEngine@eee36c
Cannot build a flow graph with the customized options:
Unable to transcode format: mpegaudio, 48000.0 Hz, 16-bit, Stereo, LittleEndian, Signed, 20000.0 frame rate, FrameSize=11264 bits
to: ULAW/rtp, 8000.0 Hz, 8-bit, Stereo
outputting to: RAW/RTP
Error: Unable to realize com.sun.media.ProcessEngine@eee36c
最后，我打开了 JMStudio（用于在 JMF 中发送/接收媒体流的内置应用程序），当我尝试流式传输 .mp3 时，我得到与运行我的应用程序时完全相同的错误。JMF 设置得很好，我检查了 PATH 和 CLASSPATH，我还安装了 mp3plugin，它也设置得很好。一切似乎都很好，但它就是行不通！至少 .mp3 不是。那么，我怎样才能让 .mp3 “走到另一端”呢？