Audio capture is unsupported

[tbu-]

The isplayback parameter of SDL_OpenAudioDevice is just set to 0 instead of being taken from the user.

[Cobrand]

The audio part of SDL2 was made long ago by someone else who probably shaped sdl2_mixer however they wanted to use it at the time. I for one didn't even know you could capture anything with SDL2, that's quite the news. I don't have much time to fix that at the moment, but I'd be happy to review any PR made about this issue ! If you or anyone else would like to fix that, fell free !

[Cobrand]

Turns out that audio recording is actually quite new, SDL 2.0.5 new actually, and it was only out a few months ago ... That must be why it wasn't implemented before.

The issue stays the same, but since this crate hasn't been actively developed in a long time, no wonder why audio capture isn't supported yet !

[shybyte]

I'm thinking about working on a PR for this feature, but 2 reasons stop me:

• SDL2_audio overhaul #646 proposed by @Cobrand is about using this occasion for a bigger breaking API change and refactoring, which might be above my current rust ability
• Sdl 2.0.5 is really new and for example not available in the standard repos of the latest ubuntu LTS (https://packages.ubuntu.com/search?suite=default&section=all&arch=any&keywords=libsdl2-2.0-0&searchon=names) Therefore I wonder how to deal with such incompatibilities. Maybe time is just not ready to add it?

[Cobrand]

If you want to to a PR, go ahead! They are always welcome! My overhaul was a plan for the long term, I haven't started to look into it yet. As with everything, I'd like to look into it as soon as possible, but easier said than done. If someone did a PR implementing that, at least I could sleep on both ears knowing that audio capture is supported even before i make that big overhaul!

Don't worry about Ubuntu LTS not having 2.0.5, I think it's totally fine to implement this either way. It will not impact those not using audio capture and being in 2.0.4, and it can only improve this current crate by adding a new feature.