WASAPI driver doesn't use the audio/output_latency parameter

[Chlipouni]

Godot version:

Godot 3.2
Godot 4.0

OS/device including version:

Windows 10

Issue description:

The file "godot/drivers/wasapi/audio_driver_wasapi.cpp" does not contain any reference to the audio/output_latency parameter in order to compute the audio buffer size.

As an example, the audio_driver_alsa.cpp uses the following lines :

	unsigned int periods = 2;
	int latency = GLOBAL_GET("audio/output_latency");
	buffer_frames = closest_power_of_2(latency * mix_rate / 1000);
	buffer_size = buffer_frames * periods;

The audio_driver_wasapi.cpp uses the following logic :

	UINT32 max_frames;
	HRESULT hr = audio_output.audio_client->GetBufferSize(&max_frames);
	ERR_FAIL_COND_V(hr != S_OK, ERR_CANT_OPEN);
	// Due to WASAPI Shared Mode we have no control of the buffer size
	buffer_frames = max_frames;

As a test, I tried to force the buffer_frames value with these modified lines of code (in both init_render_device and init_capture_device methods) :

	UINT32 max_frames = 1024;
	//HRESULT hr = audio_output.audio_client->GetBufferSize(&max_frames);
	//ERR_FAIL_COND_V(hr != S_OK, ERR_CANT_OPEN);
	// Due to WASAPI Shared Mode we have no control of the buffer size
	buffer_frames = max_frames;

With these modifications, I obtain a lower latency on Windows 10 even in shared mode.

Steps to reproduce:
Changing the value of audio/output parameter has no effect on the audio latency.
In my case I am using a Guitar USB controller and the record audio effect in Godot.
The default latency for Windows is too high and not acceptable for a guitar input.

Minimal reproduction project:

No project.
Reading the source code is enough to understand this issue.

[ts-50]

First you mentioned, "audio_driver_wasapi.cpp", then you mentioned, "audio_wasapi_driver.cpp", are these the same file?

[Calinou]

Duplicate of #30562. This will be fixed by #38210 once it's merged.