#ifndef _GNU_SOURCE #define _GNU_SOURCE #endif #include #include #include #include static uint64_t timespec_us(const struct timespec *ts) { return ts->tv_sec * 1000000LLU + ts->tv_nsec / 1000LLU; } int main(int argc, char *argv[]) { const char *dev; int r, cap; snd_pcm_hw_params_t *hwparams; snd_pcm_sw_params_t *swparams; snd_pcm_status_t *status; snd_pcm_t *pcm; unsigned rate = 44100; unsigned periods = 2; snd_pcm_uframes_t boundary, buffer_size = 44100/10; /* 100s */ int dir = 1; struct timespec start, last_timestamp = { 0, 0 }; uint64_t start_us; snd_pcm_sframes_t last_avail = 0, last_delay = 0; struct pollfd *pollfds; int n_pollfd; int64_t sample_count = 0; snd_pcm_hw_params_alloca(&hwparams); snd_pcm_sw_params_alloca(&swparams); snd_pcm_status_alloca(&status); r = clock_gettime(CLOCK_MONOTONIC, &start); assert(r == 0); start_us = timespec_us(&start); dev = argc > 1 ? argv[1] : "front:AudioPCI"; cap = argc > 2 ? atoi(argv[2]) : 0; if (cap == 0) r = snd_pcm_open(&pcm, dev, SND_PCM_STREAM_PLAYBACK, 0); else r = snd_pcm_open(&pcm, dev, SND_PCM_STREAM_CAPTURE, 0); assert(r == 0); r = snd_pcm_hw_params_any(pcm, hwparams); assert(r == 0); r = snd_pcm_hw_params_set_rate_resample(pcm, hwparams, 0); assert(r == 0); r = snd_pcm_hw_params_set_access(pcm, hwparams, SND_PCM_ACCESS_RW_INTERLEAVED); assert(r == 0); r = snd_pcm_hw_params_set_format(pcm, hwparams, SND_PCM_FORMAT_S16_LE); assert(r == 0); r = snd_pcm_hw_params_set_rate_near(pcm, hwparams, &rate, NULL); assert(r == 0); r = snd_pcm_hw_params_set_channels(pcm, hwparams, 2); assert(r == 0); r = snd_pcm_hw_params_set_periods_integer(pcm, hwparams); assert(r == 0); r = snd_pcm_hw_params_set_periods_near(pcm, hwparams, &periods, &dir); assert(r == 0); r = snd_pcm_hw_params_set_buffer_size_near(pcm, hwparams, &buffer_size); assert(r == 0); r = snd_pcm_hw_params(pcm, hwparams); assert(r == 0); r = snd_pcm_hw_params_current(pcm, hwparams); assert(r == 0); r = snd_pcm_sw_params_current(pcm, swparams); assert(r == 0); if (cap == 0) r = snd_pcm_sw_params_set_avail_min(pcm, swparams, 1); else r = snd_pcm_sw_params_set_avail_min(pcm, swparams, 0); assert(r == 0); r = snd_pcm_sw_params_set_period_event(pcm, swparams, 0); assert(r == 0); r = snd_pcm_hw_params_get_buffer_size(hwparams, &buffer_size); assert(r == 0); r = snd_pcm_sw_params_set_start_threshold(pcm, swparams, buffer_size); assert(r == 0); r = snd_pcm_sw_params_get_boundary(swparams, &boundary); assert(r == 0); r = snd_pcm_sw_params_set_stop_threshold(pcm, swparams, boundary); assert(r == 0); r = snd_pcm_sw_params_set_tstamp_mode(pcm, swparams, SND_PCM_TSTAMP_ENABLE); assert(r == 0); r = snd_pcm_sw_params(pcm, swparams); assert(r == 0); r = snd_pcm_prepare(pcm); assert(r == 0); r = snd_pcm_sw_params_current(pcm, swparams); assert(r == 0); /* assert(snd_pcm_hw_params_is_monotonic(hwparams) > 0); */ n_pollfd = snd_pcm_poll_descriptors_count(pcm); assert(n_pollfd > 0); pollfds = malloc(sizeof(struct pollfd) * n_pollfd); assert(pollfds); r = snd_pcm_poll_descriptors(pcm, pollfds, n_pollfd); assert(r == n_pollfd); if (cap) { r = snd_pcm_start(pcm); assert(r == 0); } for (;;) { snd_pcm_sframes_t avail, delay; struct timespec now, timestamp; unsigned short revents; int handled = 0; uint64_t now_us, timestamp_us; snd_pcm_state_t state; unsigned long long pos; r = poll(pollfds, n_pollfd, 0); assert(r >= 0); r = snd_pcm_poll_descriptors_revents(pcm, pollfds, n_pollfd, &revents); assert(r == 0); if (cap == 0) assert((revents & ~POLLOUT) == 0); else assert((revents & ~POLLIN) == 0); avail = snd_pcm_avail(pcm); assert(avail >= 0); r = snd_pcm_status(pcm, status); assert(r == 0); /* This assertion fails from time to time. ALSA seems to be broken */ /* assert(avail == (snd_pcm_sframes_t) snd_pcm_status_get_avail(status)); */ /* printf("%lu %lu\n", (unsigned long) avail, (unsigned long) snd_pcm_status_get_avail(status)); */ snd_pcm_status_get_htstamp(status, ×tamp); delay = snd_pcm_status_get_delay(status); state = snd_pcm_status_get_state(status); r = clock_gettime(CLOCK_MONOTONIC, &now); assert(r == 0); assert(!revents || avail > 0); if ((!cap && avail) || (cap && (unsigned)avail >= buffer_size)) { snd_pcm_sframes_t sframes; static const uint16_t psamples[2] = { 0, 0 }; uint16_t csamples[2]; if (cap == 0) sframes = snd_pcm_writei(pcm, psamples, 1); else sframes = snd_pcm_readi(pcm, csamples, 1); assert(sframes == 1); handled = 1; sample_count++; } if (!handled && memcmp(×tamp, &last_timestamp, sizeof(timestamp)) == 0 && avail == last_avail && delay == last_delay) { /* This is boring */ continue; } now_us = timespec_us(&now); timestamp_us = timespec_us(×tamp); if (cap == 0) pos = (unsigned long long) ((sample_count - handled - delay) * 1000000LU / 44100); else pos = (unsigned long long) ((sample_count - handled + delay) * 1000000LU / 44100); printf("%llu\t%llu\t%llu\t%llu\t%li\t%li\t%i\t%i\t%i\n", (unsigned long long) (now_us - start_us), (unsigned long long) (timestamp_us ? timestamp_us - start_us : 0), pos, (unsigned long long) sample_count, (signed long) avail, (signed long) delay, revents, handled, state); if (cap == 0) /** When this assert is hit, most likely something bad * happened, i.e. the avail jumped suddenly. */ assert((unsigned) avail <= buffer_size); last_avail = avail; last_delay = delay; last_timestamp = timestamp; } return 0; }