generalinputstream.java

项目描述: Fluid is a server daemon for streaming media. The latest release is built as an API for buil

package streams.general;

import streams.MediaInputStream;
import common.Configuration;
import common.Delay;
import java.io.*;

/**
 * A general media input stream with fixed delay and 
 * packet size.
 * <P>
 * This class can be used to handle possibly most medias
 * that have a fixed frame size and bitrate. It can also
 * be used in conjunction with other media input streams.
 *
 * @author Lars Samuelsson
 */
public class GeneralInputStream extends MediaInputStream {
    private byte[] packet;
    private Delay delay;
    private int packetSize;
    /**
     * Creates a general input stream.
     */
    public GeneralInputStream() {
	super();
    }
    /**
     * Configures the general input stream.
     * <P>
     * The properties that are read from the configuration
     * are: 
     * <P>
     * <UL>
     * <LI> <B> generalinputstream.packetsize </B><BR>
     *      The size of packets to be read
     * <LI> <B> generalinputstream.delay </B><BR>
     *      The delay before next packet should
     *      be fetched
     * </UL>
     * 
     * @param conf A configuration from which 
     *             parameters can be read
     */
    public void configure(Configuration conf) {
	try {
	    packetSize = Integer.parseInt(conf.getProperty("generalinputstream.packetsize"));
	    long millis = Long.parseLong(conf.getProperty("generalinputstream.delay"));
	    delay = new Delay(millis);
	}
	catch(Exception e) {
	    System.err.println("The MP3InputStream could not be configured");
	    e.printStackTrace();
	    System.exit(1);
	}
    }
    /**
     * Returns the fixed delay for this kind of media input.
     *
     * @return the delay as specified in the configuration
     */
    public Delay getDelay() {
	return delay;
    }
    /**
     * Reads a packet from the underlying input stream and 
     * returns it.
     * 
     * Uses a fixed size packet for reading and will block
     * until that packet is filled with data. 
     * 
     * @return A packet read from the underlying input stream
     */
    public byte[] read() throws IOException {
	packet = new byte[packetSize];
	if(getInputStream().read(packet) == -1) 
	    return null;
	return packet;
    }
    /**
     * The general input stream can handle any type of 
     * media.
     * 
     * @param type A media type
     * @return     true if this type is "*"
     */
    public boolean handlesMedia(String type) {
	return type.equals("*");
    }
}