pvrecorder/src/miniaudio/examples/simple_playback_sine.c

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/*
Demonstrates playback of a sine wave.
 
Since all this example is doing is playing back a sine wave, we can disable decoding (and encoding) which will slightly
reduce the size of the executable. This is done with the `MA_NO_DECODING` and `MA_NO_ENCODING` options.
 
The generation of sine wave is achieved via the `ma_waveform` API. A waveform is a data source which means it can be
seamlessly plugged into the `ma_data_source_*()` family of APIs as well.
 
A waveform is initialized using the standard config/init pattern used throughout all of miniaudio. Frames are read via
the `ma_waveform_read_pcm_frames()` API.
 
This example works with Emscripten.
*/
#define MA_NO_DECODING
#define MA_NO_ENCODING
#define MINIAUDIO_IMPLEMENTATION
#include "../miniaudio.h"
 
#include <stdio.h>
 
#ifdef __EMSCRIPTEN__
#include <emscripten.h>
 
void main_loop__em()
{
}
#endif
 
#define DEVICE_FORMAT       ma_format_f32
#define DEVICE_CHANNELS     2
#define DEVICE_SAMPLE_RATE  48000
 
void data_callback(ma_device* pDevice, void* pOutput, const void* pInput, ma_uint32 frameCount)
{
    ma_waveform* pSineWave;
 
    MA_ASSERT(pDevice->playback.channels == DEVICE_CHANNELS);
 
    pSineWave = (ma_waveform*)pDevice->pUserData;
    MA_ASSERT(pSineWave != NULL);
 
    ma_waveform_read_pcm_frames(pSineWave, pOutput, frameCount);
 
    (void)pInput;   /* Unused. */
}
 
int main(int argc, char** argv)
{
    ma_waveform sineWave;
    ma_device_config deviceConfig;
    ma_device device;
    ma_waveform_config sineWaveConfig;
 
    sineWaveConfig = ma_waveform_config_init(DEVICE_FORMAT, DEVICE_CHANNELS, DEVICE_SAMPLE_RATE, ma_waveform_type_sine, 0.2, 220);
    ma_waveform_init(&sineWaveConfig, &sineWave);
 
    deviceConfig = ma_device_config_init(ma_device_type_playback);
    deviceConfig.playback.format   = DEVICE_FORMAT;
    deviceConfig.playback.channels = DEVICE_CHANNELS;
    deviceConfig.sampleRate        = DEVICE_SAMPLE_RATE;
    deviceConfig.dataCallback      = data_callback;
    deviceConfig.pUserData         = &sineWave;
 
    if (ma_device_init(NULL, &deviceConfig, &device) != MA_SUCCESS) {
        printf("Failed to open playback device.\n");
        return -4;
    }
 
    printf("Device Name: %s\n", device.playback.name);
 
    if (ma_device_start(&device) != MA_SUCCESS) {
        printf("Failed to start playback device.\n");
        ma_device_uninit(&device);
        return -5;
    }
    
#ifdef __EMSCRIPTEN__
    emscripten_set_main_loop(main_loop__em, 0, 1);
#else
    printf("Press Enter to quit...\n");
    getchar();
#endif
    
    ma_device_uninit(&device);
    
    (void)argc;
    (void)argv;
    return 0;
}