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#include "PCM.h"
PCM::PCM(): m_phase(1000000)
{
// prepare the sample
std::string data_s = Reichwein::File::getFile("media/click.s16le");
m_data.resize(data_s.size() / 2); // src is in bytes
memcpy(m_data.data(), data_s.data(), data_s.size());
// non-blocking
if ((err = snd_pcm_open(&handle, device, SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK)) < 0) {
throw std::runtime_error(fmt::format("Playback open error: {}", snd_strerror(err)));
}
if ((err = snd_pcm_set_params(handle,
SND_PCM_FORMAT_S16_LE,
SND_PCM_ACCESS_RW_INTERLEAVED,
1,
f_sample,
1,
pcm_latency_us)) < 0) { // latency in us
throw std::runtime_error(fmt::format("Playback open error: {}", snd_strerror(err)));
}
generate();
npfd = snd_pcm_poll_descriptors_count(handle);
if (npfd < 0) {
throw std::runtime_error("snd_pcm_poll_descriptors_count() failed");
}
pfd = (struct pollfd *)malloc(npfd * sizeof(struct pollfd));
if (pfd == nullptr) {
throw std::runtime_error("alloca() error for PCM");
}
if (0 > snd_pcm_poll_descriptors(handle, pfd, npfd))
{
throw std::runtime_error("snd_pcm_poll_descriptors() failure");
}
if (0 > snd_pcm_start(handle))
{
throw std::runtime_error("PCM could not be started");
}
if (npfd != 1) {
std::cout << "Warning: " << std::to_string(npfd) << " poll fds for pcm" << std::endl;
} else if (fd() <= 2) {
std::cout << "Warning: Bad PCM fd: " << std::to_string(fd()) << std::endl;
}
}
PCM::~PCM()
{
// pass the remaining samples, otherwise they're dropped in close
err = snd_pcm_drain(handle);
if (err < 0)
std::cerr << fmt::format("snd_pcm_drain failed: {}", snd_strerror(err)) << std::endl;
snd_pcm_close(handle);
free(pfd);
}
// offset > 0: play earlier
// offset < 0: play later
void PCM::click(std::chrono::duration<double> offset)
{
snd_pcm_sframes_t delay;
if (0 > snd_pcm_delay(handle, &delay)) {
}
int64_t offset_frames{static_cast<int64_t>(offset.count() * f_sample)};
m_phase = - click_latency_frames + delay + offset_frames;
if (m_phase > 0) {
log_cout << fmt::format("phase = {}", m_phase) << std::endl;
}
}
// generate 1 buffer size
void PCM::generate()
{
int i;
for (i = 0; i < nframes; i++) {
if (m_phase < 0 || m_phase >= m_data.size())
{
buffer[i] = 0;
}
else
{
buffer[i] = m_data[m_phase];
}
m_phase++;
}
}
int PCM::fd()
{
return pfd->fd;
}
// write from buffer to ALSA PCM
void PCM::write()
{
snd_pcm_sframes_t written = snd_pcm_writei(handle, buffer, nframes);
if (written < 0) {
if (written == -EPIPE) {
std::cout << "Warning: PCM underrun" << std::endl;
}
std::cout << "Recovering." << std::endl;
written = snd_pcm_recover(handle, written, 0);
}
if (written < 0) {
throw std::runtime_error("snd_pcm_writei failed: "s + snd_strerror(written));
}
if (written != nframes) {
std::cout << "Warning: written " << std::to_string(written) << " frames instead of "<< std::to_string(nframes) << std::endl;
}
snd_pcm_sframes_t avail;
snd_pcm_sframes_t delay;
if (0 > snd_pcm_avail_delay(handle, &avail, &delay)) {
log_cout << "Error detecting avail and delay" << std::endl;
} else {
debug_cout << fmt::format("Delay: {}, avail. buffer; {} frames", delay, avail) << std::endl;
}
generate();
}
bool PCM::wait_for_event()
{
int result = poll(pfd, npfd, 10000);
if (result > 0)
{
// event
return true;
}
else if (result == 0) {
// timeout
return false;
} else {
throw std::runtime_error("Poll unsuccessful");
}
}
bool PCM::write_available()
{
snd_pcm_sframes_t result = snd_pcm_avail(handle);
if (0 > result) {
std::cerr << "Error: snd_pcm_avail()" << std::endl;
//throw std::runtime_error("snd_pcm_avail()");
}
return result >= nframes;
}
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