ALAC support

[inflation]

Hi, I’m really excited to see this project! I have some experiences on ALAC codec and am eager to help. What would be best for the collaboration?

[pdeljanov]

Hi @inflation,

Thanks for your interest!

Coincidentally enough, ALAC is something I've been working on. So far, I've made some progress on extending the IsoMp4Reader to support demuxing ALAC (among other) bitstreams and have not gotten to the decoder yet. If the decoder is something you'd like to write, then it's not too late to jump in.

There is no specification for the ALAC codec. We only have Apple's official reference implementation to work with. This means that for the most part, we just need to port the reference implementation over to Rust, and make it idiomatic (i.e., use iterators instead of for loops, etc.).

A good starting point would be to look at the PCM decoder to understand how a Symphonia decoder is structured (the Decoder trait). Then check out the FLAC decoder to see how a similar lossless audio decoder is implemented.

If this is something you're interested in working on, you can jump right in.

Since this is something I was planning to include in v0.5 (next release), please keep me posted occasionally on your progress, and let me know if you won't be able to complete it for whatever reason.

Of course, please feel free to reach out and ask if you have any questions or are getting stuck.

[pdeljanov]

To give you a head start, I pushed the stubbed out AlacDecoder I had previously implemented to the alac branch.

[inflation]

Sure, I will read the source and start on porting the reference implementation.

[inflation]

I'll need more time on this because of personal issues. Feel free to take it over. Sorry.

[pdeljanov]

Hey @inflation, I hope you are doing okay.

I'm not in a rush to push a new release, so if you are still interested in it after things settle down, feel free to jump back in if the ticket is still open.