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#include "audio.h"
#include <FAudio.h>
#include <SDL3/SDL.h>
#include <math.h>
struct AudioContext
{
FAudio *faudio;
FAudioMasteringVoice *mastering_voice;
};
struct AudioVoice
{
AudioContext *context;
FAudioSourceVoice *voice;
};
struct AudioFilter
{
AudioContext *context;
FAudioFilterParameters params;
};
void faudio_destroy_context(AudioContext *p_context)
{
FAudioVoice_DestroyVoice(p_context->mastering_voice);
FAudio_Release(p_context->faudio);
delete p_context;
}
AudioVoice *faudio_create_voice(AudioContext *p_context, float *p_buffer, size_t p_buffer_size, int p_sample_rate, int p_num_channels)
{
// create a source voice
FAudioWaveFormatEx waveFormat;
waveFormat.wFormatTag = 3;
waveFormat.nChannels = p_num_channels;
waveFormat.nSamplesPerSec = p_sample_rate;
waveFormat.nAvgBytesPerSec = p_sample_rate * 4;
waveFormat.nBlockAlign = p_num_channels * 4;
waveFormat.wBitsPerSample = 32;
waveFormat.cbSize = 0;
FAudioSourceVoice *voice;
FAudioSendDescriptor send;
FAudioVoiceSends sends;
sends.SendCount = 1;
sends.pSends = &send;
send.Flags = FAUDIO_SEND_USEFILTER;
send.pOutputVoice = p_context->mastering_voice;
uint32_t hr = FAudio_CreateSourceVoice(p_context->faudio, &voice, &waveFormat, FAUDIO_VOICE_USEFILTER, FAUDIO_DEFAULT_FREQ_RATIO, NULL, &sends, NULL);
if (hr != 0) {
return NULL;
}
FAudioVoice_SetVolume(voice, 0.0f, FAUDIO_COMMIT_NOW);
// submit the array
FAudioBuffer buffer = { 0 };
buffer.AudioBytes = 4 * p_buffer_size * p_num_channels;
buffer.pAudioData = (uint8_t *)p_buffer;
buffer.Flags = FAUDIO_END_OF_STREAM;
buffer.PlayBegin = 0;
buffer.PlayLength = p_buffer_size;
buffer.LoopBegin = 0;
buffer.LoopLength = p_buffer_size;
buffer.LoopCount = FAUDIO_LOOP_INFINITE;
FAudioSourceVoice_SubmitSourceBuffer(voice, &buffer, NULL);
// start the voice playing
FAudioSourceVoice_Start(voice, 0, FAUDIO_COMMIT_NOW);
// return a voice struct
AudioVoice *result = new AudioVoice();
result->context = p_context;
result->voice = voice;
return result;
}
void faudio_voice_destroy(AudioVoice *p_voice)
{
FAudioVoice_DestroyVoice(p_voice->voice);
}
void faudio_voice_set_volume(AudioVoice *p_voice, float p_volume)
{
FAudioVoice_SetVolume(p_voice->voice, p_volume, FAUDIO_COMMIT_NOW);
}
void faudio_voice_set_frequency(AudioVoice *p_voice, float p_frequency)
{
FAudioSourceVoice_SetFrequencyRatio(p_voice->voice, p_frequency, FAUDIO_COMMIT_NOW);
}
AudioFilter *faudio_create_filter(AudioContext *p_context)
{
AudioFilter *filter = new AudioFilter();
filter->context = p_context;
return filter;
}
void faudio_filter_update(AudioFilter *p_filter, int p_type, float p_cutoff_frequency, float p_q)
{
if (p_type != -1)
{
p_filter->params.Type = FAudioFilterType(p_type);
p_filter->params.Frequency = (float) (2 * sin(PI * p_cutoff_frequency / 44100));
p_filter->params.OneOverQ = (float)(1.0 / p_q);
}
else
{
// documentation of XAUDIO2_FILTER_PARAMETERS:
// Setting XAUDIO2_FILTER_PARAMETERS with the following values is acoustically equivalent to the filter being fully bypassed.
p_filter->params.Type = FAudioLowPassFilter;
p_filter->params.Frequency = 1.0f;
p_filter->params.OneOverQ = 1.0f;
}
}
void faudio_filter_apply(AudioFilter *p_filter, AudioVoice *p_voice)
{
FAudioVoice_SetFilterParameters(p_voice->voice, &p_filter->params, FAUDIO_COMMIT_NOW);
}
void faudio_output_filter_apply(AudioFilter *p_filter, AudioVoice *p_voice)
{
FAudioVoice_SetOutputFilterParameters(p_voice->voice, p_voice->context->mastering_voice, &p_filter->params, FAUDIO_COMMIT_NOW);
}
AudioContext *faudio_create_context()
{
// setup function pointers
audio_destroy_context = faudio_destroy_context;
audio_create_voice = faudio_create_voice;
audio_voice_destroy = faudio_voice_destroy;
audio_voice_set_volume = faudio_voice_set_volume;
audio_voice_set_frequency = faudio_voice_set_frequency;
audio_create_filter = faudio_create_filter;
audio_filter_update = faudio_filter_update;
audio_filter_apply = faudio_filter_apply;
audio_output_filter_apply = faudio_output_filter_apply;
// create Faudio object
FAudio *faudio;
uint32_t hr = FAudioCreate(&faudio, 0, FAUDIO_DEFAULT_PROCESSOR);
if (hr != 0)
return NULL;
// create a mastering voice
FAudioMasteringVoice *mastering_voice;
hr = FAudio_CreateMasteringVoice(faudio, &mastering_voice, FAUDIO_DEFAULT_CHANNELS, FAUDIO_DEFAULT_SAMPLERATE, 0, 0, NULL);
if (hr != 0)
return NULL;
// return a context object
AudioContext *context = new AudioContext();
context->faudio = faudio;
context->mastering_voice = mastering_voice;
return context;
}
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