AudiobookRecorder/src/it/sauronsoftware/jave/FFMPEGExecutor.java

/*
 * JAVE - A Java Audio/Video Encoder (based on FFMPEG)
 * 
 * Copyright (C) 2008-2009 Carlo Pelliccia (www.sauronsoftware.it)
 * 
 * This program 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.
 *
 * This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package it.sauronsoftware.jave;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;

/**
 * A ffmpeg process wrapper.
 * 
 * @author Carlo Pelliccia
 */
class FFMPEGExecutor {

	/**
	 * The path of the ffmpeg executable.
	 */
	private String ffmpegExecutablePath;

	/**
	 * Arguments for the executable.
	 */
	private ArrayList<String> args = new ArrayList<String>();

	/**
	 * The process representing the ffmpeg execution.
	 */
	private Process ffmpeg = null;

	/**
	 * A process killer to kill the ffmpeg process with a shutdown hook, useful
	 * if the jvm execution is shutted down during an ongoing encoding process.
	 */
	private ProcessKiller ffmpegKiller = null;

	/**
	 * A stream reading from the ffmpeg process standard output channel.
	 */
	private InputStream inputStream = null;

	/**
	 * A stream writing in the ffmpeg process standard input channel.
	 */
	private OutputStream outputStream = null;

	/**
	 * A stream reading from the ffmpeg process standard error channel.
	 */
	private InputStream errorStream = null;

	/**
	 * It build the executor.
	 * 
	 * @param ffmpegExecutablePath
	 *            The path of the ffmpeg executable.
	 */
	public FFMPEGExecutor(String ffmpegExecutablePath) {
		this.ffmpegExecutablePath = ffmpegExecutablePath;
	}

	/**
	 * Adds an argument to the ffmpeg executable call.
	 * 
	 * @param arg
	 *            The argument.
	 */
	public void addArgument(String arg) {
		args.add(arg);
	}

	/**
	 * Executes the ffmpeg process with the previous given arguments.
	 * 
	 * @throws IOException
	 *             If the process call fails.
	 */
	public void execute() throws IOException {
		int argsSize = args.size();
		String[] cmd = new String[argsSize + 1];
		cmd[0] = ffmpegExecutablePath;
		for (int i = 0; i < argsSize; i++) {
			cmd[i + 1] = (String) args.get(i);
		}

		Runtime runtime = Runtime.getRuntime();
		ffmpeg = runtime.exec(cmd);
		ffmpegKiller = new ProcessKiller(ffmpeg);
		runtime.addShutdownHook(ffmpegKiller);
		inputStream = ffmpeg.getInputStream();
		outputStream = ffmpeg.getOutputStream();
		errorStream = ffmpeg.getErrorStream();
	}

	/**
	 * Returns a stream reading from the ffmpeg process standard output channel.
	 * 
	 * @return A stream reading from the ffmpeg process standard output channel.
	 */
	public InputStream getInputStream() {
		return inputStream;
	}

	/**
	 * Returns a stream writing in the ffmpeg process standard input channel.
	 * 
	 * @return A stream writing in the ffmpeg process standard input channel.
	 */
	public OutputStream getOutputStream() {
		return outputStream;
	}

	/**
	 * Returns a stream reading from the ffmpeg process standard error channel.
	 * 
	 * @return A stream reading from the ffmpeg process standard error channel.
	 */
	public InputStream getErrorStream() {
		return errorStream;
	}

	/**
	 * If there's a ffmpeg execution in progress, it kills it.
	 */
	public void destroy() {
		if (inputStream != null) {
			try {
				inputStream.close();
			} catch (Throwable t) {
				;
			}
			inputStream = null;
		}
		if (outputStream != null) {
			try {
				outputStream.close();
			} catch (Throwable t) {
				;
			}
			outputStream = null;
		}
		if (errorStream != null) {
			try {
				errorStream.close();
			} catch (Throwable t) {
				;
			}
			errorStream = null;
		}
		if (ffmpeg != null) {
			ffmpeg.destroy();
			ffmpeg = null;
		}
		if (ffmpegKiller != null) {
			Runtime runtime = Runtime.getRuntime();
			runtime.removeShutdownHook(ffmpegKiller);
			ffmpegKiller = null;
		}
	}

}