AVIOContext.java

/*
 * Copyright (c) 2001 Fabrice Bellard
 * Copyright (c) 2011 Michael Zucchi
 *
 * This file is part of jjmpeg, a java binding to ffmpeg's libraries.
 *
 * jjmpeg is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * jjmpeg 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with jjmpeg.  If not, see <http://www.gnu.org/licenses/>.
 */
package au.notzed.jjmpeg;

import au.notzed.jjmpeg.exception.AVIOException;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;

/**
 * Wrapper for AVIOContext - allows custom streams to
 * be implemented from java.
 * 
 * @author notzed
 */
public abstract class AVIOContext extends AVIOContextAbstract {

	public static final int AVSEEK_SIZE = 0x10000;
	//
	public static final int SEEK_SET = 0;
	public static final int SEEK_CUR = 1;
	public static final int SEEK_END = 2;
	//
	public static final int ALLOC_WRITE = 1;
	public static final int ALLOC_STREAMED = 2;
	// flags for open
	public static final int URL_RDONLY;
	public static final int URL_WRONLY;
	public static final int URL_RDWR;

	static {
		// These flags changed at version 53

		// TODO: should be done at build time as part of genjjmpeg.pl
		int[] vers = AVNative.getVersions();
		if (vers[AVNative.LIBAVFORMAT_VERSION] >= 53) {
			URL_RDONLY = 1;
			URL_WRONLY = 2;
			URL_RDWR = 3;
		} else {
			URL_RDONLY = 0;
			URL_WRONLY = 1;
			URL_RDWR = 2;
		}
	}

	protected AVIOContext(ByteBuffer p) {
		setNative(new AVIOContextNative(this, p, 0));
	}

	static AVIOContext create(ByteBuffer p) {
		// These could call back to the C versions
		return new AVIOContext(p) {

			@Override
			public int readPacket(ByteBuffer dst) {
				throw new UnsupportedOperationException("Not supported yet.");
			}

			@Override
			public int writePacket(ByteBuffer src) {
				throw new UnsupportedOperationException("Not supported yet.");
			}

			@Override
			public long seek(long offset, int whence) {
				throw new UnsupportedOperationException("Not supported yet.");
			}
		};
	}

	public static AVIOContext open(String url, int flags) throws AVIOException {
		ByteBuffer res = ByteBuffer.allocateDirect(4).order(ByteOrder.nativeOrder());
		ByteBuffer context;

		System.out.println("open url " + url + " flags " + flags);
		context = AVIOContextNative.open(url, flags, res);

		if (context == null) {
			throw new AVIOException(res.asIntBuffer().get(0), "Failed to open " + url);
		}

		return create(context);
	}

	/**
	 * Initialise the aviocontext.
	 * @param size
	 * @param flags Taken from ALLOC_* flags
	 */
	protected AVIOContext(int size, int flags) {
		this(AVIOContextNative.allocContext(size, flags));
		AVIOContextNative.bind(this, n.p);
	}

	/**
	 * Call av_probe_input_buffer() on this stream
	 * @param filename
	 * @param offset
	 * @param max_probe_size
	 * @return 
	 */
	public AVInputFormat probeInput(String filename, int offset, int max_probe_size) {
		ByteBuffer b = AVIOContextNative.probeInput(n.p, filename, offset, max_probe_size);

		if (b != null) {
			return AVInputFormat.create(b);
		}

		return null;
	}

	/**
	 * Release resources.  This must be called otherwise the object
	 * will not be garbage collected.
	 *
	 * TODO: still thinking of how to implement the lifecycle.
	 */
	public abstract int readPacket(ByteBuffer dst);

	public abstract int writePacket(ByteBuffer src);

	public abstract long seek(long offset, int whence);
}

class AVIOContextNative extends AVIOContextNativeAbstract {

	private final int type;

	AVIOContextNative(AVObject o, ByteBuffer p, int type) {
		super(o, p);

		this.type = type;
	}

	@Override
	public void dispose() {
		if (p != null) {
			if (type == 1) {
				AVIOContextNative.unbind((AVIOContext) this.get(), p);
			}
			super.dispose();
		}
	}

	static native ByteBuffer allocContext(int size, int flags);

	static native ByteBuffer probeInput(ByteBuffer p, String filename, int offset, int max_probe_size);

	static native ByteBuffer open(String url, int flags, ByteBuffer error_ptr);

	/**
	 * Bind AVIOContext to java instance
	 */
	static native void bind(AVIOContext self, ByteBuffer p);

	/**
	 * Unbind AVIOContext from java instance, and free memory too.
	 */
	static native void unbind(AVIOContext self, ByteBuffer p);
}