Ich möchte MP3-Videos in MP3-Audiodateien auf einer Android-Plattform konvertieren? Wie kann ich es tun? Eigentlich teste ich etwas JAR. Erstens kann die JAAD-Bibliothek zum Testen verwendet werden.

import java.io.File;
import java.io.RandomAccessFile;
import java.util.List;

import net.sourceforge.jaad.aac.Decoder;
import net.sourceforge.jaad.aac.SampleBuffer;
import net.sourceforge.jaad.mp4.MP4Container;
import net.sourceforge.jaad.mp4.api.AudioTrack;
import net.sourceforge.jaad.mp4.api.Frame;
import net.sourceforge.jaad.mp4.api.Movie;
import net.sourceforge.jaad.mp4.api.Track;
import net.sourceforge.jaad.util.wav.WaveFileWriter;

public class Main2 {
    public static void main(String[] args) {
    System.out.println("dfd");
    try {
        decodeMP4("C:/a/input.mp4","./out.wav");
    } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    System.out.println("over");

}
private static void decodeMP4(String in, String out) throws Exception {
    WaveFileWriter wav = null;
    try {
        final MP4Container cont = new MP4Container(new RandomAccessFile(in, "r"));
        final Movie movie = cont.getMovie();
        final List<Track> tracks = movie.getTracks(AudioTrack.AudioCodec.AAC);
        if(tracks.isEmpty()) throw new Exception("movie does not contain any AAC track");
        final AudioTrack track = (AudioTrack) tracks.get(0);

        wav = new WaveFileWriter(new File(out), track.getSampleRate(), track.getChannelCount(), track.getSampleSize());

        final Decoder dec = new Decoder(track.getDecoderSpecificInfo());

        Frame frame;
        final SampleBuffer buf = new SampleBuffer();
        while(track.hasMoreFrames()) {
            frame = track.readNextFrame();
            dec.decodeFrame(frame.getData(), buf);
            wav.write(buf.getData());
        }
    }
    finally {
        if(wav!=null) wav.close();
    }
}
}

aber es wirft einen Fehler

"java.lang.ClassCastException: net.sourceforge.jaad.mp4.boxes.impl.PixelAspectRatioBox cannot be cast to net.sourceforge.jaad.mp4.boxes.impl.sampleentries.codec.CodecSpecificBox
    at net.sourceforge.jaad.mp4.api.VideoTrack.<init>(VideoTrack.java:62)
    at net.sourceforge.jaad.mp4.api.Movie.createTrack(Movie.java:65)
    at net.sourceforge.jaad.mp4.api.Movie.<init>(Movie.java:46)
    at net.sourceforge.jaad.mp4.MP4Container.getMovie(MP4Container.java:134)
    at Main2.decodeMP4(Main2.java:30)
    at Main2.main(Main2.java:18)"