WASAPI Exclusive mode distorted audio playback #1022

Rapandrasmus · 2025-07-28T21:53:47Z

Rapandrasmus
Jul 28, 2025

For context I am making a general purpose audio engine built with miniaudio with the intent of being used in rhythm games or other games that need fast responsive audio. That's why I want to give the option to use exclusive mode.
However testing on my devices (some headphones and some monitors) with WASAPI on Windows 11, the engine succesfully initialises but the audio is horribly distorted, I'd describe it as "noise-y" and as-if the bit depth has been reduced. When I use shared mode the audio plays back as it should.

I am curious if any of you have experienced this, have found the cause and/or have found a way to fix it? I'm hoping this is a fault on my part and not miniaudio or my devices. I'll update this discussion if I end up finding the solution on my own.

Extra note: I tested exclusive mode in a different application that has its own WASAPI implementation and it threw an error and disabled exclusive mode, so I have a hunch there's something wrong with my devices that miniaudio might not be detecting. Otherwise the other application might be doing something wrong 🤷

Answered by mackron

Jul 29, 2025

I'm assuming you are calling ma_engine_read_pcm_frames() in your data callback? If so, this is your problem:

device_config.playback.format = ma_format_unknown;

ma_engine is always ma_format_f32. Change that line to this:

device_config.playback.format = ma_format_f32;

View full answer

mackron · 2025-07-29T08:23:32Z

mackron
Jul 29, 2025
Maintainer

How are you initializing your ma_device object? Are you using ma_engine at all?

0 replies

Rapandrasmus · 2025-07-29T08:44:14Z

Rapandrasmus
Jul 29, 2025
Author

I am using ma_engine.
I set everything, the sounds, the resource manager and the engine to match the data format of the device
ma_device is initialised like this:
`

ma_device_config device_config = ma_device_config_init(ma_device_type_playback);

// Datacallback delegates

Miniaudio::
Miniaudio::

if ( NULL &&  NULL)
{
	device_config.dataCallback = DataCallbackNoDelegate;
}
else if (onDataCallback != NULL && onPreDataCallback != NULL)
{
	device_config.dataCallback = DataCallbackBothDelegate;
}
else if (onDataCallback != NULL)
{
	device_config.dataCallback = DataCallbackPostDelegate;
}
else
{
	device_config.dataCallback = DataCallbackPreDelegate;
}

device_config.playback.format = ma_format_unknown; // Set to unknown to use native format
device_config.playback.channels = 0; // Set to 0 to use native channels
device_config.sampleRate = 0; // Set to 0 to use native sampleRate
device_config.playback.shareMode = exclusive ? ma_share_mode_exclusive : ma_share_mode_shared;
device_config.performanceProfile = ma_performance_profile_low_latency;
device_config.wasapi.noAutoConvertSRC = true; // Neccesary to allow WASAPI low latency mode
device_config.wasapi.usage = ma_wasapi_usage_pro_audio;
device_config.periodSizeInFrames = prefBufferSizeFrames;
device_config.noFixedSizedCallback = noFixedSizeCallback;
device_config.noPreSilencedOutputBuffer = true;
device_config.noClip = true;

if (!defaultDevice)
{
	ma_uint32 deviceCount;

	ma_device_info* pDeviceInfos;

	result = GetDeviceInfos(&pDeviceInfos, &deviceCount);
	if (result != MA_SUCCESS || deviceIndex >= deviceCount) defaultDevice = true;

	if (!defaultDevice) device_config.playback.pDeviceID = &pDeviceInfos[deviceIndex].id;
}

result = ma_device_init(&context, &device_config, &device);
if (result != MA_SUCCESS)
{
	ma_context_uninit(&context);
	contextInitialised = false;
	return result;
}

result = ma_device_start(&device);
if (result != MA_SUCCESS) 
{
	ma_context_uninit(&context);
	contextInitialised = false;
	ma_device_uninit(&device);
	return result;
}`

4 replies

mackron Jul 29, 2025
Maintainer

I'm assuming you are calling ma_engine_read_pcm_frames() in your data callback? If so, this is your problem:

device_config.playback.format = ma_format_unknown;

ma_engine is always ma_format_f32. Change that line to this:

device_config.playback.format = ma_format_f32;

Answer selected by Rapandrasmus

Rapandrasmus Jul 29, 2025
Author

Thanks, that worked like it should
However I'm curious as to why ma_engine is always ma_format_f32? Wouldn't matching the device format be more efficient since conversion can be avoided for devices that dont use f32?

mackron Jul 29, 2025
Maintainer

It's totally unpractical because then I would need to have mixing and effect processing implementations for every format: f32, s16, s32, s24 and u8. Also need to consider custom effect nodes - you can't expect effect nodes to implement every supported sample format. Just simpler to do everything as f32 and then do a single post-processing data conversion.

Rapandrasmus Jul 29, 2025
Author

Understandable

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