uk.co.caprica.vlcj.media.callback.DefaultCallbackMedia Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of vlcj Show documentation
Java Framework for the vlc Media Player.
There is a newer version: 5.0.0-M1
/*
 * This file is part of VLCJ.
 *
 * VLCJ 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.
 *
 * VLCJ 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 VLCJ.  If not, see .
 *
 * Copyright 2009-2019 Caprica Software Limited.
 */

package uk.co.caprica.vlcj.media.callback;

import java.io.IOException;

import com.sun.jna.Pointer;

/**
 * Implementation of a {@link CallbackMedia} media that uses a Java byte array for an IO buffer when reading media data.
 * 
 * A sub-class need only provide an implementation for {@link #onRead(byte[], int)}.
 * 

 * This implementation uses a Java byte array, you can instead get direct access to the native buffer by sub-classing
 * {@link AbstractCallbackMedia} directly.
 */
public abstract class DefaultCallbackMedia extends AbstractCallbackMedia {

    /**
     * Default IO buffer size.
     */
    private static final int DEFAULT_BUFFER_SIZE = 10240;

    /**
     * IO buffer.
     */
    private final byte[] ioBuffer;

    /**
     * Create a new media instance with a default IO buffer size.
     *
     * @param seekable true if the media is seekable; false if it is not
     */
    public DefaultCallbackMedia(boolean seekable) {
        this(seekable, DEFAULT_BUFFER_SIZE);
    }

    /**
     * Create a new media instance.
     *
     * @param seekable true if the media is seekable; false if it is not
     * @param ioBufferSize IO buffer size
     */
    public DefaultCallbackMedia(boolean seekable, int ioBufferSize) {
        super(seekable);
        this.ioBuffer = new byte[ioBufferSize];
    }

    @Override
    protected final int onRead(Pointer buffer, int bufferSize) throws IOException {
        int bytesRead = onRead(ioBuffer, Math.min(ioBuffer.length, bufferSize));
        if (bytesRead > 0) {
            buffer.write(0, ioBuffer, 0, bytesRead);
        }
        return bytesRead;
    }

    /**
     * Template method used by sub-classes to populate the buffer with media data.
     * 
     * It is allowable for implementations to block in this method waiting for IO, but care must be taken not
     * to block indefinitely otherwise the native media player can not be stopped.
     *
     * @param buffer IO buffer
     * @param bufferSize maximum number of bytes to fill
     * @return number of bytes read, or -1 if the end of the media was reached
     * @throws IOException if an error occurs
     */
    protected abstract int onRead(byte[] buffer, int bufferSize) throws IOException;

}