Using mp4parser , how can I handle videos that are taken from Uri and ContentResolver?

Question

Background

We want to let the user choose a video from any app, and then trim a video to be of max of 5 seconds.

The problem

For getting a Uri to

Answer 1

Next a snipped shows how to open a MediaStore Uri with IsoFile from Mp4Parser. So, you can see how to get a FileChannel from a Uri.

public void test(@NonNull final Context context, @NonNull final Uri uri) throws IOException
{
    ParcelFileDescriptor fileDescriptor = null;

    try
    {
        final ContentResolver resolver = context.getContentResolver();
        fileDescriptor = resolver.openFileDescriptor(uri, "rw");

        if (fileDescriptor == null)
        {
            throw new IOException("Failed to open Uri.");
        }

        final FileDescriptor  fd          = fileDescriptor.getFileDescriptor();
        final FileInputStream inputStream = new FileInputStream(fd);
        final FileChannel     fileChannel = inputStream.getChannel();

        final DataSource channel = new FileDataSourceImpl(fileChannel);
        final IsoFile    isoFile = new IsoFile(channel);

        ... do what you need ....
    }
    finally
    {
        if (fileDescriptor != null)
        {
            fileDescriptor.close();
        }
    }
}