I haven't tried it yet, but seems Java MP4 Parser library is what I've been looking for. It is able to read and edit metadata, cross platform and seems to be light in file size.
Java MP4 Parser
A Java API to read, write and create MP4 container. Manipulating
containers is different from encoding and decoding videos and audio.
Using the library
The library is published to Maven repositories. Each release is pushed
to a staging repository which is published on the release page. On
request specific releases can be pushed to maven central.
com.googlecode.mp4parser
isoparser
1.1.7
For projects that do not use a dependency management tool each
release's artifacts (jar, javadoc-jar, source-jar) are attached to the
release page. Please be aware that the project requires the
aspectj-rt.jar library.
What can you do?
Typical tasks for the MP4 Parser are:
- Muxing audio/video into an MP4 file
- Append recordings that use same encode settings
- Adding/Changing metadata
- Shorten recordings by omitting frames My examples will all use H264 and AAC as these two codecs are most typical for MP4 files. AC-3 is
also not uncommon as the codec is well known from DVD. There are also
MP4 files with H263/MPEG-2 video tracks but they are no longer used
widespread as most android phones. You can also
Muxing Audio/Video
The API and the process is straight-forward:
You wrap each raw format file into an appropriate Track object.
H264TrackImpl h264Track = new H264TrackImpl(new
FileDataSourceImpl("video.h264")); AACTrackImpl aacTrack = new
AACTrackImpl(new FileDataSourceImpl("audio.aac"));
These Track object are then added to a Movie object
Movie movie = new Movie();
movie.addTrack(h264Track);
movie.addTrack(aacTrack);
The Movie object is fed into an MP4Builder to create the container.
Container mp4file = new DefaultMp4Builder().build(movie);
Write the container to an appropriate sink.
FileChannel fc = new FileOutputStream(new
File("output.mp4")).getChannel(); mp4file.writeContainer(fc);
fc.close(); There are cases where the frame rate is signalled out of
band or is known in advance so that the H264 doesn't contain it
literally. In this case you will have to supply it to the constructor.
There are Track implementations for the following formats:
and additionally two subtitle tracks that do not directly wrap a raw
format but they are conceptually similar.
Typical Issues
Audio and video are not in sync. Whenever there are problems with
timing possible make sure to start
Audio starts before video
In AAC there are always samplerate/1024 sample/s so each sample's
duration is 1000 * 1024 / samplerate milliseconds.
- 48KHz => ~21.3ms
- 44.1KHz => ~23.2ms
By omitting samples from the start you can easily shorten the audio
track. Remove as many as you need. You will not be able to match audio
and video exactly with that but the human perception is more sensible
to early audio than to late audio.
Remember: If someone is only 10 meters away the delay between audio
and video is >30ms. The brain is used to that!
AACTrackImpl aacTrackOriginal = new AACTrackImpl(new
FileDataSourceImpl("audio.aac")); // removes the first sample and
shortens the AAC track by ~22ms CroppedTrack aacTrackShort = new
CroppedTrack(aacTrackOriginal, 1, aacTrack.getSamples().size());
Append Recordings with Same Encode Settings
It is important to emphasize that you cannot append any two tracks
with:
- Different resolutions
- Different frame-rates
What can't you do?
Create JPEGs from a movie. No - this is no decoder. The MP4 Parser
doesn't know how to do that. Create a movie from JPEGs
