com.googlecode.mp4parser fails for mp3 audio file?

Question

I am using the com.googlecode.mp4parser library to merge audio files. I have an external audio mp3 file which I store in raw resources. This file fails to merge due to following exception, Below is my code :

Reading a file from raw folder :

InputStream is = context.getResources().openRawResource(R.raw.my_mp3_file);
        OutputStream output = null;
        try {
            File file = new File(context.getFilesDir(), "silence.mp3");
            if(!file.exists()) {
                file.createNewFile();
            }
            output = new FileOutputStream(file);
            byte[] buffer = new byte[4 * 1024]; // or other buffer size
            int read;

            while ((read = is.read(buffer)) != -1) {
                output.write(buffer, 0, read);
            }
            output.flush();
            output.close();
            fileReference= file;
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace(); // handle exception, define IOException and others
        } finally {
            try {
                is.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

Code that reads movie ( Which is failing ) :

if(fileReference.exists()) {
                    Movie m = new MovieCreator().build(fileReference.getAbsolutePath());
                }

While getting this Movie m my code fails throwing the exception :

java.lang.NullPointerException: Attempt to invoke virtual method 'java.util.List com.coremedia.iso.boxes.MovieBox.getBoxes(java.lang.Class)' on a null object reference

It works for some mp3 files fails for raw resource files ? What's wrong here ?

Answer 1

Here are my conclusion and solution after a lot of research MP4Parser for merging audio and video only use .m4a extension

String root = Environment.getExternalStorageDirectory().toString();
            String audio = root + "/" + "tests.m4a";
            String video = root + "/" + "output.mp4";
            String output = root + "/" + "aud_vid.mp4";
            mux(video, audio, output);

and here is the method

public boolean mux(String videoFile, String audioFile, String outputFile) {
    Movie video;
    try {
        video = new MovieCreator().build(videoFile);
    } catch (RuntimeException e) {
        e.printStackTrace();
        return false;
    } catch (IOException e) {
        e.printStackTrace();
        return false;
    }

    Movie audio;
    try {
        audio = new MovieCreator().build(audioFile);
    } catch (IOException e) {
        e.printStackTrace();
        return false;
    } catch (NullPointerException e) {
        e.printStackTrace();
        return false;
    }

    Track audioTrack = audio.getTracks().get(0);
    video.addTrack(audioTrack);

    Container out = new DefaultMp4Builder().build(video);

    FileOutputStream fos;
    try {
        fos = new FileOutputStream(outputFile);
    } catch (FileNotFoundException e) {
        e.printStackTrace();
        return false;
    }
    BufferedWritableFileByteChannel byteBufferByteChannel = new BufferedWritableFileByteChannel(fos);
    try {
        out.writeContainer(byteBufferByteChannel);
        byteBufferByteChannel.close();
        fos.close();
    } catch (IOException e) {
        e.printStackTrace();
        return false;
    }
    return true;
}

private static class BufferedWritableFileByteChannel implements WritableByteChannel {
    private static final int BUFFER_CAPACITY = 1000000;

    private boolean isOpen = true;
    private final OutputStream outputStream;
    private final ByteBuffer byteBuffer;
    private final byte[] rawBuffer = new byte[BUFFER_CAPACITY];

    private BufferedWritableFileByteChannel(OutputStream outputStream) {
        this.outputStream = outputStream;
        this.byteBuffer = ByteBuffer.wrap(rawBuffer);
    }

    @Override
    public int write(ByteBuffer inputBuffer) throws IOException {
        int inputBytes = inputBuffer.remaining();

        if (inputBytes > byteBuffer.remaining()) {
            dumpToFile();
            byteBuffer.clear();

            if (inputBytes > byteBuffer.remaining()) {
                throw new BufferOverflowException();
            }
        }

        byteBuffer.put(inputBuffer);

        return inputBytes;
    }

    @Override
    public boolean isOpen() {
        return isOpen;
    }

    @Override
    public void close() throws IOException {
        dumpToFile();
        isOpen = false;
    }

    private void dumpToFile() {
        try {
            outputStream.write(rawBuffer, 0, byteBuffer.position());
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }
}

Answer 2

Seem like this issue happens because Google devs have forgotten to handle that NullPointerException case. After several hours diving into the code base, I finally found the solution and It works very fine, you can try this:

         Movie movie;         
         try{
            movie = MovieCreator.build(videoPath);
         }catch(NullPointerException e){
             Log.d("AsyncTask", "Catch null getMovieBoxes");
             FileDataSourceImpl fileDataSource = new FileDataSourceImpl(new File(videoPath));
             IsoFile isoFile = new IsoFile(fileDataSource);
             List<TrackBox> trackBoxes = isoFile.getBoxes(TrackBox.class);
             for (TrackBox trackBox : trackBoxes) {
                  SchemeTypeBox schm = Path.getPath(trackBox, "mdia[0]/minf[0]/stbl[0]/stsd[0]/enc.[0]/sinf[0]/schm[0]");
                  if (schm != null && (schm.getSchemeType().equals("cenc") || schm.getSchemeType().equals("cbc1"))) {
                                movie.addTrack(new CencMp4TrackImplImpl(fileDataSource.toString() + "[" + trackBox.getTrackHeaderBox().getTrackId() + "]", trackBox));
                  } else {
                  movie.addTrack(new Mp4TrackImpl(fileDataSource.toString() + "[" + trackBox.getTrackHeaderBox().getTrackId() + "]" , trackBox));
                  }
              }

         }