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Support float32 output in SDL2 audio backend (with int16 fallback)

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This commit is contained in:
Nikita Lisitsa 2025-10-23 18:40:30 +03:00
parent 64ffe27c2a
commit e23455356d
1 changed files with 34 additions and 15 deletions
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35
libs/sdl2/source/audio_engine.cpp
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@ -8,10 +8,7 @@
#include <SDL2/SDL.h> #include <SDL2/SDL.h>
#include <mutex>
#include <atomic>
#include <vector> #include <vector>
#include <optional>
#include <cmath> #include <cmath>
#include <iomanip> #include <iomanip>
@ -39,6 +36,7 @@ namespace psemek::sdl2
audio::channel_ptr output_; audio::channel_ptr output_;
template <typename SampleType>
static void callback(void * userdata, std::uint8_t * stream, int len); static void callback(void * userdata, std::uint8_t * stream, int len);
}; };
@ -48,14 +46,23 @@ namespace psemek::sdl2
SDL_AudioSpec desired, obtained; SDL_AudioSpec desired, obtained;
desired.freq = audio::frequency; desired.freq = audio::frequency;
desired.channels = 2; desired.channels = 2;
desired.format = AUDIO_S16SYS; desired.format = AUDIO_F32SYS;
desired.samples = 256; desired.samples = 256;
desired.callback = &callback; desired.callback = &callback<float>;
desired.userdata = this; desired.userdata = this;
if (device_ = SDL_OpenAudioDevice(nullptr, 0, &desired, &obtained, 0); device_ == 0) if (device_ = SDL_OpenAudioDevice(nullptr, 0, &desired, &obtained, 0); device_ == 0)
{
log::error() << "SDL_OpenAudioDevice failed: " << SDL_GetError();
log::error() << "Fallback to int16 audio output";
desired.format = AUDIO_S16SYS;
desired.callback = &callback<std::int16_t>;
if (device_ = SDL_OpenAudioDevice(nullptr, 0, &desired, &obtained, 0); device_ == 0)
{
fail("SDL_OpenAudioDevice failed:"); fail("SDL_OpenAudioDevice failed:");
}
}
log::info() << "Initialized audio: " << static_cast<int>(obtained.channels) << " channels, " << obtained.freq << " Hz, " << obtained.samples << " samples"; log::info() << "Initialized audio: " << static_cast<int>(obtained.channels) << " channels, " << obtained.freq << " Hz, " << obtained.samples << " samples " << (desired.format == AUDIO_F32SYS ? "f32" : "i16");
buffer_.resize(obtained.samples * obtained.channels); buffer_.resize(obtained.samples * obtained.channels);
output_ = std::make_shared<audio::channel>(); output_ = std::make_shared<audio::channel>();
@ -67,6 +74,7 @@ namespace psemek::sdl2
SDL_CloseAudioDevice(device_); SDL_CloseAudioDevice(device_);
} }
template <typename SampleType>
void audio_engine_impl::callback(void * userdata, std::uint8_t * dst_u8, int len) void audio_engine_impl::callback(void * userdata, std::uint8_t * dst_u8, int len)
{ {
static std::string const profiler_str = "audio"; static std::string const profiler_str = "audio";
@ -74,7 +82,7 @@ namespace psemek::sdl2
auto self = static_cast<audio_engine_impl *>(userdata); auto self = static_cast<audio_engine_impl *>(userdata);
auto stream = self->output()->stream(); auto stream = self->output()->stream();
std::int16_t * dst = reinterpret_cast<std::int16_t *>(dst_u8); SampleType * dst = reinterpret_cast<SampleType *>(dst_u8);
if (!self->thread_registered_) if (!self->thread_registered_)
{ {
@ -82,7 +90,10 @@ namespace psemek::sdl2
self->thread_registered_ = true; self->thread_registered_ = true;
} }
std::size_t const size = len / 2; std::size_t const size = len / sizeof(SampleType);
if constexpr (std::is_same_v<SampleType, std::int16_t>)
{
std::size_t read = 0; std::size_t read = 0;
if (stream) if (stream)
read = stream->read({self->buffer_.data(), size}); read = stream->read({self->buffer_.data(), size});
@ -90,6 +101,14 @@ namespace psemek::sdl2
for (auto s : self->buffer_) for (auto s : self->buffer_)
*dst++ = static_cast<std::int16_t>(std::max(std::min((65535.f * s - 1.f) / 2.f, 32767.f), -32768.f)); *dst++ = static_cast<std::int16_t>(std::max(std::min((65535.f * s - 1.f) / 2.f, 32767.f), -32768.f));
}
else
{
std::size_t read = 0;
if (stream)
read = stream->read({dst, size});
std::fill(dst + read, dst + size, 0.f);
}
if (auto duration = prof.duration(); duration > (size * audio::inv_frequency / 2)) if (auto duration = prof.duration(); duration > (size * audio::inv_frequency / 2))
log::warning() << "Audio can't keep up, callback took " << std::setprecision(5) << (1000.0 * duration) << " ms"; log::warning() << "Audio can't keep up, callback took " << std::setprecision(5) << (1000.0 * duration) << " ms";