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hints: Added SDL_HINT_AUDIO_ENFORCE_MINIMUM_SPEC.

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Fixes #14426.
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2025-11-30 23:26:02 -05:00
parent ea1514ab63
commit b7c8b2f29a
2 changed files with 44 additions and 11 deletions
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30
include/SDL3/SDL_hints.h
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@@ -493,6 +493,36 @@ extern "C" {
*/
#define SDL_HINT_AUDIO_DUMMY_TIMESCALE "SDL_AUDIO_DUMMY_TIMESCALE"
/**
* A variable controlling whether SDL enforces a minimum audio device spec.
*
* By default, SDL will require devices to be opened at a minimum spec
* (at time of writing: 44100Hz, stereo, Sint16 format), so if something
* lower quality tries to open the device first, it doesn't ruin audio
* for the next thing that opens a device. For example, if a VoIP library
* wants Uint8, 8000Hz, mono output, it doesn't force the entire game to
* this state simply because it got there first.
*
* However, an app that knows it will definitely be the only thing opening
* a device, and wants to open it at a lower spec, might be able to avoid
* some otherwise-unnecessary conversions by bypassing this minimum
* requirement.
*
* Note that even without the minimum enforcement, the system might choose a
* different format/channels/frequency than requested by the app; this hint
* just removes SDL's minimum policy.
*
* The variable can be set to the following values:
*
* - "0": Audio device mimimum formats _are not_ enforced.
* - "1": Audio device minimum formats _are_ enforced. (default)
*
* This hint should be set before an audio device is opened.
*
* \since This hint is available since SDL 3.4.0.
*/
#define SDL_HINT_AUDIO_ENFORCE_MINIMUM_SPEC "SDL_AUDIO_ENFORCE_MINIMUM_SPEC"
/**
* A variable controlling the default audio format.
*

25
src/audio/SDL_audio.c
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@@ -1800,18 +1800,21 @@ static bool OpenPhysicalAudioDevice(SDL_AudioDevice *device, const SDL_AudioSpec
SDL_copyp(&spec, inspec ? inspec : &device->default_spec);
PrepareAudioFormat(device->recording, &spec);
/* We impose a simple minimum on device formats. This prevents something low quality, like an old game using S8/8000Hz audio,
from ruining a music thing playing at CD quality that tries to open later, or some VoIP library that opens for mono output
ruining your surround-sound game because it got there first.
These are just requests! The backend may change any of these values during OpenDevice method! */
if (!SDL_GetHintBoolean(SDL_HINT_AUDIO_ENFORCE_MINIMUM_SPEC, true)) {
SDL_copyp(&device->spec, &spec);
} else {
/* We impose a simple minimum on device formats. This prevents something low quality, like an old game using S8/8000Hz audio,
from ruining a music thing playing at CD quality that tries to open later, or some VoIP library that opens for mono output
ruining your surround-sound game because it got there first.
These are just requests! The backend may change any of these values during OpenDevice method! */
const SDL_AudioFormat minimum_format = device->recording ? DEFAULT_AUDIO_RECORDING_FORMAT : DEFAULT_AUDIO_PLAYBACK_FORMAT;
const int minimum_channels = device->recording ? DEFAULT_AUDIO_RECORDING_CHANNELS : DEFAULT_AUDIO_PLAYBACK_CHANNELS;
const int minimum_freq = device->recording ? DEFAULT_AUDIO_RECORDING_FREQUENCY : DEFAULT_AUDIO_PLAYBACK_FREQUENCY;
device->spec.format = (SDL_AUDIO_BITSIZE(minimum_format) >= SDL_AUDIO_BITSIZE(spec.format)) ? minimum_format : spec.format;
device->spec.channels = SDL_max(minimum_channels, spec.channels);
device->spec.freq = SDL_max(minimum_freq, spec.freq);
}
const SDL_AudioFormat minimum_format = device->recording ? DEFAULT_AUDIO_RECORDING_FORMAT : DEFAULT_AUDIO_PLAYBACK_FORMAT;
const int minimum_channels = device->recording ? DEFAULT_AUDIO_RECORDING_CHANNELS : DEFAULT_AUDIO_PLAYBACK_CHANNELS;
const int minimum_freq = device->recording ? DEFAULT_AUDIO_RECORDING_FREQUENCY : DEFAULT_AUDIO_PLAYBACK_FREQUENCY;
device->spec.format = (SDL_AUDIO_BITSIZE(minimum_format) >= SDL_AUDIO_BITSIZE(spec.format)) ? minimum_format : spec.format;
device->spec.channels = SDL_max(minimum_channels, spec.channels);
device->spec.freq = SDL_max(minimum_freq, spec.freq);
device->sample_frames = SDL_GetDefaultSampleFramesFromFreq(device->spec.freq);
SDL_UpdatedAudioDeviceFormat(device); // start this off sane.