void AudioHandler::_audio_task() {
std::array<int16_t, 512> audioBuffer;
while(true) {
while(currentCassettes.empty())
xTaskNotifyWait(0, 0, nullptr, portMAX_DELAY);
audioBuffer.fill(0);
for(uint16_t i=0; i<audioBuffer.size(); i++) {
for(auto &c : currentCassettes)
audioBuffer[i] += c.get_chunk();
}
size_t written_samples = 0;
i2s_write(i2s_port, audioBuffer.data(), 1024, &written_samples, portMAX_DELAY);
for(auto i=currentCassettes.begin(); i<currentCassettes.end(); i++) {
if(i->is_done())
currentCassettes.erase(i);
}
if(currentCassettes.empty())
i2s_zero_dma_buffer(i2s_port);
}
}
static void setup_triangle_sine_waves(int bits)
{
int *samples_data = malloc(((bits+8)/16)*SAMPLE_PER_CYCLE*4);
unsigned int i, sample_val;
double sin_float, triangle_float, triangle_step = (double) pow(2, bits) / SAMPLE_PER_CYCLE;
size_t i2s_bytes_write = 0;
printf("\r\nTest bits=%d free mem=%d, written data=%d\n", bits, esp_get_free_heap_size(), ((bits+8)/16)*SAMPLE_PER_CYCLE*4);
triangle_float = -(pow(2, bits)/2 - 1);
for(i = 0; i < SAMPLE_PER_CYCLE; i++) {
sin_float = sin(i * PI / 180.0);
if(sin_float >= 0)
triangle_float += triangle_step;
else
triangle_float -= triangle_step;
sin_float *= (pow(2, bits)/2 - 1);
if (bits == 16) {
sample_val = 0;
sample_val += (short)triangle_float;
sample_val = sample_val << 16;
sample_val += (short) sin_float;
samples_data[i] = sample_val;
} else if (bits == 24) { //1-bytes unused
samples_data[i*2] = ((int) triangle_float) << 8;
samples_data[i*2 + 1] = ((int) sin_float) << 8;
} else {
samples_data[i*2] = ((int) triangle_float);
samples_data[i*2 + 1] = ((int) sin_float);
}
}
i2s_set_clk(I2S_NUM, SAMPLE_RATE, bits, 2);
//Using push
// for(i = 0; i < SAMPLE_PER_CYCLE; i++) {
// if (bits == 16)
// i2s_push_sample(0, &samples_data[i], 100);
// else
// i2s_push_sample(0, &samples_data[i*2], 100);
// }
// or write
i2s_write(I2S_NUM, samples_data, ((bits+8)/16)*SAMPLE_PER_CYCLE*4, &i2s_bytes_write, 100);
free(samples_data);
}
