How to write metadata to mp4 file using mp4parser?

Question

I'm using mp4parser to mux h264 and aac file which are re-encoded from orginal video file,how can I write the metadata of the original video to the new mp4 file? Or is there a common method to write metadata to mp4 file?

Answer 1

It seems that the 'mp4parser' library (https://code.google.com/p/mp4parser/), supports writing Metadata to mp4 files in Android. However, I've found there's little-to-no documentation on how to do this, beyond a few examples in their codebase. I've had some luck with the following example, which writes XML metadata into the 'moov/udta/meta' box:

https://github.com/copiousfreetime/mp4parser/blob/master/examples/src/main/java/com/googlecode/mp4parser/stuff/ChangeMetaData.java

Answer 2

If you consider the alternatives you might want to look at JCodec for this purpose. It now has the org.jcodec.movtool.MetadataEditor API (and a matching CLI org.jcodec.movtool.MetadataEditorMain).

Their documentation contains many samples: http://jcodec.org/docs/working_with_mp4_metadata.html

So basically when you want to add some metadata you need to know what key(s) it corresponds to. One way to find out is to inspect a sample file that already has the metadata you need. For this you can run the JCodec's CLI tool that will just print out all the existing metadata fields (keys with values):

./metaedit <file.mp4>

Then when you know the key you want to work with you can either use the same CLI tool:

# Changes the author of the movie
./metaedit -f -si ©ART=New\ value file.mov

or the same thing via the Java API:

MetadataEditor mediaMeta = MetadataEditor.createFrom(new
    File("file.mp4"));
Map<Integer, MetaValue> meta = mediaMeta.getItunesMeta();
meta.put(0xa9415254, MetaValue.createString("New value")); // fourcc for '©ART'
mediaMeta.save(false); // fast mode is off

To delete a metadata field from a file:

MetadataEditor mediaMeta = MetadataEditor.createFrom(new
    File("file.mp4"));
Map<Integer, MetaValue> meta = mediaMeta.getItunesMeta();
meta.remove(0xa9415254); // removes the '©ART'
mediaMeta.save(false); // fast mode is off

To convert string to integer fourcc you can use something like:

byte[] bytes = "©ART".getBytes("iso8859-1");
int fourcc =
    ByteBuffer.wrap(bytes).order(ByteOrder.BIG_ENDIAN).getInt();

If you want to edit/delete the android metadata you'll need to use a different set of fucntion (because it's stored differently than iTunes metadata):

./metaedit -sk com.android.capture.fps,float=25.0 file.mp4

OR alternatively the same through the API:

MetadataEditor mediaMeta = MetadataEditor.createFrom(new
    File("file.mp4"));
Map<String, MetaValue> meta = mediaMeta.getKeyedMeta();
meta.put("com.android.capture.fps", MetaValue.createFloat(25.));
mediaMeta.save(false); // fast mode is off

Answer 3

metadata and MP4 is a really problem. There is no generally supported specification. But this is only one part of the problem.

• Prob (1): When to write metadata
• Prob (2): What to write

Prob (1) is relatively easy to solve: Just extend the DefaultMp4Builder or the FragmentedMp4Builder on your own and override the

protected ParsableBox createUdta(Movie movie) {
    return null;
}

with something meaningful. E.g.:

protected ParsableBox createUdta(Movie movie) {
    UserDataBox udta = new UserDataBox();
    CopyrightBox copyrightBox = new CopyrightBox();
    copyrightBox.setCopyright("All Rights Reserved, me, myself and I, 2015");
    copyrightBox.setLanguage("eng");
    udta.addBox(copyrightBox);
    return udta;
}

some people used that to write apple compatible metadata but even though there are some classes in my code I never really figured out what works and what not. You might want to have a look into Apple's specification here

And yes: I'm posting this a year to late.