Decoding Encoded Audio Data (MP3s, etc) on Android Without Playing It

Question

Short version: What is the best way to get data encoded in an MP3 (and ideally in an AAC/Ogg/WMA) into a Java array or ByteBuffer that I can then manipulate?

I'm putting together a program that has slowing down and speeding up sound files as one of its features. This works fine for WAV files, which are a header plus the exact binary data that needs to be sent to the speaker, and now I need to implement it for MP3 (ideally, this would also support AAC, Ogg, and WMA, but since those are less popular formats this is not required). Android does not expose an interface to decode the MP3 without playing it, so I need to create that interface.

Three options present themselves, though I'm open to others:

1) Write my own decoder. I already have a functional frame detector that I was hoping to use for option (3), and now should only need to implement the Huffman decoding tables.

2) Use JLayer, or an equivalent Java library, to handle the decoding. I'm not entirely clear on what the license ramifications are here.

3) Connect to the libmedia library/MediaPlayerService. This is what SoundPool does, and the amount of use of that service make me believe that while it's officially unstable, that implementation isn't going anywhere. This means writing JNI code to connect to the service, but I'm finding that that's a deep rabbit hole. At the surface, I'm having trouble with the sp<> template.

Answer 1

I did that with libmad and the NDK. JLayer is way to slow and the media framework is a moving target. You can find info and source code at http://apistudios.com/hosted/marzec/badlogic/wordpress/?p=231

Answer 2

I have not tried it, but mp3transform is LGPL.