AudioStream/Playback only exposes virtual methods

[stechyo]

Godot version

4.2

godot-cpp version

4.2

System information

Linux

Issue description

AudioStream and AudioStreamPlayback only expose virtual methods. This is sufficient for creating total overrides of existing stream/playbacks, but not for e.g. intercepting an existing stream playback's mixed audio frames and changing them. Calling a native stream playback's _mix() returns 0 mixed frames, presumably because of the GDVIRTUAL macros used in the engine code (forgive any misunderstanding, but I presume that when those macros are removed what gets generated into extension bindings is the non-virtual method, similar to what's exposed on GDScript/C#).

How feasible would it be to allow direct use of audio methods?

Thank you!

Steps to reproduce

Attempt to call _mix for a native stream playback and check that zero frames have been mixed.

// stream_playback is a Ref<AudioStreamPlaybackMP3> in this case
AudioFrame input[frames];
int mixed = stream_playback->_mix(input, rate_scale, frames);
// mixed == 0, all audio frames in `input` are zero

Minimal reproduction project

N/A

[dsnopek]

Thanks for the report!

So, you want to be able to get an instance of, say, AudioStreamPlaybackMP3 and call it's mix() method (NOTE: without the leading _ score)? I think that's doable. Someone would need make a PR changing AudioStreamPlayback::_bind_methods() to bind the mix() method. Does it make sense to bind the other non-virtual methods too?

Is that a PR that you're interested in making? It'd be a fairly simple contribution to the engine :-)

[stechyo]

Yeah, I can do that. Just wanted to understand if there wasn't any opposition to exposing the method to GDExt. I'll see if I can publish a PR today, thanks!

[dsnopek]

I don't think there'll be any opposition from the GDExtension team - the audio team may have reasons they don't want those exposed, but they don't tend to see godot-cpp issues. :-) You'll probably need their approval on the Godot PR, so you could discuss it with them there, or if you want to discuss before writing code, you could make a Godot issue or proposal.