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 args = new ArrayList();

    /**
     * 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 ) {
        if ( ffmpegExecutablePath.contains( " " ) ) {
            this.ffmpegExecutablePath = "\"" + ffmpegExecutablePath + "\"";
        }
        else {
            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 ) {
                t.printStackTrace();

            }
            inputStream = null;
        }
        if ( outputStream != null ) {
            try {
                outputStream.close();
            }
            catch ( Throwable t ) {
                t.printStackTrace();

            }
            outputStream = null;
        }
        if ( errorStream != null ) {
            try {
                errorStream.close();
            }
            catch ( Throwable t ) {
                t.printStackTrace();

            }
            errorStream = null;
        }
        if ( ffmpeg != null ) {
            ffmpeg.destroy();
            ffmpeg = null;
        }
        if ( ffmpegKiller != null ) {

            Runtime runtime = Runtime.getRuntime();
            runtime.removeShutdownHook( ffmpegKiller );
            ffmpegKiller = null;
        }
    }

}