/* Get the pcm boundary value. */ static int get_boundary(snd_pcm_t *pcm, snd_pcm_uframes_t *boundary) { snd_pcm_sw_params_t *sw_params; int rc; snd_pcm_sw_params_alloca(&sw_params); rc = snd_pcm_sw_params_current(pcm, sw_params); if (rc < 0) { fprintf(stderr, "sw_params_current: %s\n", snd_strerror(rc)); return rc; } rc = snd_pcm_sw_params_get_boundary(sw_params, boundary); if (rc < 0) { fprintf(stderr, "get_boundary: %s\n", snd_strerror(rc)); return rc; } return 0; }
bool CAESinkALSA::InitializeSW(AEAudioFormat &format) { snd_pcm_sw_params_t *sw_params; snd_pcm_uframes_t boundary; snd_pcm_sw_params_alloca(&sw_params); memset(sw_params, 0, snd_pcm_sw_params_sizeof()); snd_pcm_sw_params_current (m_pcm, sw_params); snd_pcm_sw_params_set_start_threshold (m_pcm, sw_params, INT_MAX); snd_pcm_sw_params_set_silence_threshold(m_pcm, sw_params, 0); snd_pcm_sw_params_get_boundary (sw_params, &boundary); snd_pcm_sw_params_set_silence_size (m_pcm, sw_params, boundary); snd_pcm_sw_params_set_avail_min (m_pcm, sw_params, format.m_frames); if (snd_pcm_sw_params(m_pcm, sw_params) < 0) { CLog::Log(LOGERROR, "CAESinkALSA::InitializeSW - Failed to set the parameters"); return false; } return true; }
bool AudioInputALSA::PrepSwParams(void) { snd_pcm_sw_params_t* swparams; snd_pcm_sw_params_alloca(&swparams); snd_pcm_uframes_t boundary; if (AlsaBad(snd_pcm_sw_params_current(pcm_handle, swparams), "failed to get swparams")) return false; if (AlsaBad(snd_pcm_sw_params_get_boundary(swparams, &boundary), "failed to get boundary")) return false; // explicit start, not auto start if (AlsaBad(snd_pcm_sw_params_set_start_threshold(pcm_handle, swparams, boundary), "failed to set start threshold")) return false; if (AlsaBad(snd_pcm_sw_params_set_stop_threshold(pcm_handle, swparams, boundary), "failed to set stop threshold")) return false; if (AlsaBad(snd_pcm_sw_params(pcm_handle, swparams), "failed to set software parameters")) return false; return true; }
int main(int argc, char *argv[]) { const char *dev; int r, cap, count = 0; 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, last_us = 0; snd_pcm_sframes_t last_avail = 0, last_delay = 0; struct pollfd *pollfds; int n_pollfd; int64_t sample_count = 0; struct sched_param sp; r = -1; #ifdef _POSIX_PRIORITY_SCHEDULING sp.sched_priority = 5; r = pthread_setschedparam(pthread_self(), SCHED_RR, &sp); #endif if (r) printf("Could not get RT prio. :(\n"); 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); printf("Starting. Buffer size is %u frames\n", (unsigned int) buffer_size); 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); if (count++ % 50 == 0) printf("Elapsed\tCPU\tALSA\tPos\tSamples\tavail\tdelay\trevents\thandled\tstate\n"); printf("%llu\t%llu\t%llu\t%llu\t%llu\t%li\t%li\t%i\t%i\t%i\n", (unsigned long long) (now_us - last_us), (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; last_us = now_us; } return 0; }
static int ao_alsa_init(dtaudio_output_t *aout, dtaudio_para_t *para) { memcpy(&wrapper->para, para, sizeof(dtaudio_para_t)); snd_pcm_t *alsa_handle; snd_pcm_hw_params_t *alsa_hwparams; snd_pcm_sw_params_t *alsa_swparams; snd_pcm_uframes_t size; snd_pcm_uframes_t boundary; alsa_ctx_t *ctx = (alsa_ctx_t *)malloc(sizeof(*ctx)); if (!ctx) { return -1; } wrapper->ao_priv = ctx; int afmt = format_to_alsa(wrapper->para.bps); uint32_t channels = wrapper->para.dst_channels; uint32_t sr = wrapper->para.dst_samplerate; int bytes_per_sample = snd_pcm_format_physical_width(afmt) * channels / 8; int err = 0; err = snd_pcm_open(&alsa_handle, "default", SND_PCM_STREAM_PLAYBACK, 0); if (err < 0) { dt_error(TAG, "%s,%d: %s\n", __func__, __LINE__, snd_strerror(err)); free(ctx); wrapper->ao_priv = NULL; return -1; } snd_pcm_hw_params_alloca(&alsa_hwparams); snd_pcm_sw_params_alloca(&alsa_swparams); err = snd_pcm_hw_params_any(alsa_handle, alsa_hwparams); if (err < 0) { dt_error(TAG, "%s,%d: %s\n", __func__, __LINE__, snd_strerror(err)); return -1; } err = snd_pcm_hw_params_set_access(alsa_handle, alsa_hwparams, SND_PCM_ACCESS_RW_INTERLEAVED); if (err < 0) { dt_error(TAG, "%s,%d: %s\n", __func__, __LINE__, snd_strerror(err)); return -1; } err = snd_pcm_hw_params_set_format(alsa_handle, alsa_hwparams, afmt); if (err < 0) { dt_error(TAG, "%s,%d: %s\n", __func__, __LINE__, snd_strerror(err)); return -1; } err = snd_pcm_hw_params_set_channels_near(alsa_handle, alsa_hwparams, &channels); if (err < 0) { dt_error(TAG, "%s,%d: %s\n", __func__, __LINE__, snd_strerror(err)); return -1; } err = snd_pcm_hw_params_set_rate_near(alsa_handle, alsa_hwparams, &sr, NULL); if (err < 0) { dt_error(TAG, "%s,%d: %s\n", __func__, __LINE__, snd_strerror(err)); return -1; } err = snd_pcm_hw_params(alsa_handle, alsa_hwparams); if (err < 0) { dt_error(TAG, "%s,%d: %s\n", __func__, __LINE__, snd_strerror(err)); return -1; } /****************************************************************** * Set HW Params Finish ******************************************************************/ /* buffer size means the entire size of alsa pcm buffer size*/ err = snd_pcm_hw_params_get_buffer_size(alsa_hwparams, &size); if (err < 0) { dt_error(TAG, "%s,%d: %s\n", __func__, __LINE__, snd_strerror(err)); return -1; } ctx->buf_size = size * bytes_per_sample; /*period size means count processed every interrupt*/ err = snd_pcm_hw_params_get_period_size(alsa_hwparams, &size, NULL); if (err < 0) { dt_error(TAG, "%s,%d: %s\n", __func__, __LINE__, snd_strerror(err)); return -1; } ctx->trunk_size = size * bytes_per_sample; dt_info(TAG, "outburst: %d, bytes_per_sample: %d, buffersize: %d\n", ctx->trunk_size, bytes_per_sample, ctx->buf_size); /****************************************************************** * set sw params ******************************************************************/ err = snd_pcm_sw_params_current(alsa_handle, alsa_swparams); if (err < 0) { dt_error(TAG, "%s,%d: %s\n", __func__, __LINE__, snd_strerror(err)); return -1; } #if SND_LIB_VERSION >= 0x000901 err = snd_pcm_sw_params_get_boundary(alsa_swparams, &boundary); #else boundary = 0x7fffffff; #endif err = snd_pcm_sw_params_set_start_threshold(alsa_handle, alsa_swparams, size); if (err < 0) { dt_error(TAG, "%s,%d: %s\n", __func__, __LINE__, snd_strerror(err)); return -1; } err = snd_pcm_sw_params_set_stop_threshold(alsa_handle, alsa_swparams, boundary); if (err < 0) { dt_error(TAG, "%s,%d: %s\n", __func__, __LINE__, snd_strerror(err)); return -1; } #if SND_LIB_VERSION >= 0x000901 err = snd_pcm_sw_params_set_silence_size(alsa_handle, alsa_swparams, boundary); if (err < 0) { dt_error(TAG, "%s,%d: %s\n", __func__, __LINE__, snd_strerror(err)); return -1; } #endif err = snd_pcm_sw_params(alsa_handle, alsa_swparams); if (err < 0) { dt_error(TAG, "%s,%d: %s\n", __func__, __LINE__, snd_strerror(err)); return -1; } ctx->pause_support = snd_pcm_hw_params_can_pause(alsa_hwparams); //buf size limit ctx->buf_threshold = bytes_per_sample * sr * DEFAULT_TIME_SIZE / 1000; dt_info(TAG, "alsa audio init ok! outburst:%d thres:%d \n", ctx->trunk_size, ctx->buf_threshold); ctx->handle = alsa_handle; ctx->channels = wrapper->para.dst_channels; ctx->bps = wrapper->para.bps; ctx->samplerate = wrapper->para.dst_samplerate; return 0; }
static int initialize_device(struct audio_info_struct *ai) { snd_pcm_hw_params_t *hw; int i; snd_pcm_format_t format; unsigned int rate; snd_pcm_uframes_t buffer_size; snd_pcm_uframes_t period_size; snd_pcm_sw_params_t *sw; snd_pcm_uframes_t boundary; snd_pcm_hw_params_alloca(&hw); if (snd_pcm_hw_params_any(ai->handle, hw) < 0) { fprintf(stderr, "initialize_device(): no configuration available\n"); return -1; } if (snd_pcm_hw_params_set_access(ai->handle, hw, SND_PCM_ACCESS_RW_INTERLEAVED) < 0) { fprintf(stderr, "initialize_device(): device does not support interleaved access\n"); return -1; } format = SND_PCM_FORMAT_UNKNOWN; for (i = 0; i < NUM_FORMATS; ++i) { if (ai->format == format_map[i].mpg123) { format = format_map[i].alsa; break; } } if (format == SND_PCM_FORMAT_UNKNOWN) { fprintf(stderr, "initialize_device(): invalid sample format %d\n", ai->format); errno = EINVAL; return -1; } if (snd_pcm_hw_params_set_format(ai->handle, hw, format) < 0) { fprintf(stderr, "initialize_device(): cannot set format %s\n", snd_pcm_format_name(format)); return -1; } if (snd_pcm_hw_params_set_channels(ai->handle, hw, ai->channels) < 0) { fprintf(stderr, "initialize_device(): cannot set %d channels\n", ai->channels); return -1; } rate = ai->rate; if (snd_pcm_hw_params_set_rate_near(ai->handle, hw, &rate, NULL) < 0) { fprintf(stderr, "initialize_device(): cannot set rate %u\n", rate); return -1; } if (!rates_match(ai->rate, rate)) { fprintf(stderr, "initialize_device(): rate %ld not available, using %u\n", ai->rate, rate); /* return -1; */ } buffer_size = rate * BUFFER_LENGTH; if (snd_pcm_hw_params_set_buffer_size_near(ai->handle, hw, &buffer_size) < 0) { fprintf(stderr, "initialize_device(): cannot set buffer size\n"); return -1; } period_size = buffer_size / 4; if (snd_pcm_hw_params_set_period_size_near(ai->handle, hw, &period_size, NULL) < 0) { fprintf(stderr, "initialize_device(): cannot set period size\n"); return -1; } if (snd_pcm_hw_params(ai->handle, hw) < 0) { fprintf(stderr, "initialize_device(): cannot set hw params\n"); return -1; } snd_pcm_sw_params_alloca(&sw); if (snd_pcm_sw_params_current(ai->handle, sw) < 0) { fprintf(stderr, "initialize_device(): cannot get sw params\n"); return -1; } /* start playing after the first write */ if (snd_pcm_sw_params_set_start_threshold(ai->handle, sw, 1) < 0) { fprintf(stderr, "initialize_device(): cannot set start threshold\n"); return -1; } if (snd_pcm_sw_params_get_boundary(sw, &boundary) < 0) { fprintf(stderr, "initialize_device(): cannot get boundary\n"); return -1; } /* never stop on underruns */ if (snd_pcm_sw_params_set_stop_threshold(ai->handle, sw, boundary) < 0) { fprintf(stderr, "initialize_device(): cannot set stop threshold\n"); return -1; } /* wake up on every interrupt */ if (snd_pcm_sw_params_set_avail_min(ai->handle, sw, 1) < 0) { fprintf(stderr, "initialize_device(): cannot set min avail\n"); return -1; } #if 0 /* always write as many frames as possible */ if (snd_pcm_sw_params_set_xfer_align(ai->handle, sw, 1) < 0) { fprintf(stderr, "initialize_device(): cannot set transfer alignment\n"); return -1; } #endif /* play silence when there is an underrun */ if (snd_pcm_sw_params_set_silence_size(ai->handle, sw, boundary) < 0) { fprintf(stderr, "initialize_device(): cannot set silence size\n"); return -1; } if (snd_pcm_sw_params(ai->handle, sw) < 0) { fprintf(stderr, "initialize_device(): cannot set sw params\n"); return -1; } return 0; }
bool setParameters (unsigned int sampleRate, int numChannels, int bufferSize) { if (handle == nullptr) return false; JUCE_ALSA_LOG ("ALSADevice::setParameters(" << deviceID << ", " << (int) sampleRate << ", " << numChannels << ", " << bufferSize << ")"); snd_pcm_hw_params_t* hwParams; snd_pcm_hw_params_alloca (&hwParams); if (snd_pcm_hw_params_any (handle, hwParams) < 0) { // this is the error message that aplay returns when an error happens here, // it is a bit more explicit that "Invalid parameter" error = "Broken configuration for this PCM: no configurations available"; return false; } if (snd_pcm_hw_params_set_access (handle, hwParams, SND_PCM_ACCESS_RW_INTERLEAVED) >= 0) // works better for plughw.. isInterleaved = true; else if (snd_pcm_hw_params_set_access (handle, hwParams, SND_PCM_ACCESS_RW_NONINTERLEAVED) >= 0) isInterleaved = false; else { jassertfalse; return false; } enum { isFloatBit = 1 << 16, isLittleEndianBit = 1 << 17, onlyUseLower24Bits = 1 << 18 }; const int formatsToTry[] = { SND_PCM_FORMAT_FLOAT_LE, 32 | isFloatBit | isLittleEndianBit, SND_PCM_FORMAT_FLOAT_BE, 32 | isFloatBit, SND_PCM_FORMAT_S32_LE, 32 | isLittleEndianBit, SND_PCM_FORMAT_S32_BE, 32, SND_PCM_FORMAT_S24_3LE, 24 | isLittleEndianBit, SND_PCM_FORMAT_S24_3BE, 24, SND_PCM_FORMAT_S24_LE, 32 | isLittleEndianBit | onlyUseLower24Bits, SND_PCM_FORMAT_S16_LE, 16 | isLittleEndianBit, SND_PCM_FORMAT_S16_BE, 16 }; bitDepth = 0; for (int i = 0; i < numElementsInArray (formatsToTry); i += 2) { if (snd_pcm_hw_params_set_format (handle, hwParams, (_snd_pcm_format) formatsToTry [i]) >= 0) { const int type = formatsToTry [i + 1]; bitDepth = type & 255; converter.reset (createConverter (isInput, bitDepth, (type & isFloatBit) != 0, (type & isLittleEndianBit) != 0, (type & onlyUseLower24Bits) != 0, numChannels, isInterleaved)); break; } } if (bitDepth == 0) { error = "device doesn't support a compatible PCM format"; JUCE_ALSA_LOG ("Error: " + error); return false; } int dir = 0; unsigned int periods = 4; snd_pcm_uframes_t samplesPerPeriod = (snd_pcm_uframes_t) bufferSize; if (JUCE_ALSA_FAILED (snd_pcm_hw_params_set_rate_near (handle, hwParams, &sampleRate, 0)) || JUCE_ALSA_FAILED (snd_pcm_hw_params_set_channels (handle, hwParams, (unsigned int ) numChannels)) || JUCE_ALSA_FAILED (snd_pcm_hw_params_set_periods_near (handle, hwParams, &periods, &dir)) || JUCE_ALSA_FAILED (snd_pcm_hw_params_set_period_size_near (handle, hwParams, &samplesPerPeriod, &dir)) || JUCE_ALSA_FAILED (snd_pcm_hw_params (handle, hwParams))) { return false; } snd_pcm_uframes_t frames = 0; if (JUCE_ALSA_FAILED (snd_pcm_hw_params_get_period_size (hwParams, &frames, &dir)) || JUCE_ALSA_FAILED (snd_pcm_hw_params_get_periods (hwParams, &periods, &dir))) latency = 0; else latency = (int) frames * ((int) periods - 1); // (this is the method JACK uses to guess the latency..) JUCE_ALSA_LOG ("frames: " << (int) frames << ", periods: " << (int) periods << ", samplesPerPeriod: " << (int) samplesPerPeriod); snd_pcm_sw_params_t* swParams; snd_pcm_sw_params_alloca (&swParams); snd_pcm_uframes_t boundary; if (JUCE_ALSA_FAILED (snd_pcm_sw_params_current (handle, swParams)) || JUCE_ALSA_FAILED (snd_pcm_sw_params_get_boundary (swParams, &boundary)) || JUCE_ALSA_FAILED (snd_pcm_sw_params_set_silence_threshold (handle, swParams, 0)) || JUCE_ALSA_FAILED (snd_pcm_sw_params_set_silence_size (handle, swParams, boundary)) || JUCE_ALSA_FAILED (snd_pcm_sw_params_set_start_threshold (handle, swParams, samplesPerPeriod)) || JUCE_ALSA_FAILED (snd_pcm_sw_params_set_stop_threshold (handle, swParams, boundary)) || JUCE_ALSA_FAILED (snd_pcm_sw_params (handle, swParams))) { return false; } #if JUCE_ALSA_LOGGING // enable this to dump the config of the devices that get opened snd_output_t* out; snd_output_stdio_attach (&out, stderr, 0); snd_pcm_hw_params_dump (hwParams, out); snd_pcm_sw_params_dump (swParams, out); #endif numChannelsRunning = numChannels; return true; }
/** * Allocate the memory-mapped buffer for direct sound, and set up the * callback. */ static int DSDB_CreateMMAP(IDsDriverBufferImpl* pdbi) { snd_pcm_t *pcm = pdbi->pcm; snd_pcm_format_t format; snd_pcm_uframes_t frames, ofs, avail, psize, boundary; unsigned int channels, bits_per_sample, bits_per_frame; int err, mmap_mode; const snd_pcm_channel_area_t *areas; snd_pcm_hw_params_t *hw_params = pdbi->hw_params; snd_pcm_sw_params_t *sw_params = pdbi->sw_params; void *buf; mmap_mode = snd_pcm_type(pcm); if (mmap_mode == SND_PCM_TYPE_HW) TRACE("mmap'd buffer is a direct hardware buffer.\n"); else if (mmap_mode == SND_PCM_TYPE_DMIX) TRACE("mmap'd buffer is an ALSA dmix buffer\n"); else TRACE("mmap'd buffer is an ALSA type %d buffer\n", mmap_mode); err = snd_pcm_hw_params_get_period_size(hw_params, &psize, NULL); err = snd_pcm_hw_params_get_format(hw_params, &format); err = snd_pcm_hw_params_get_buffer_size(hw_params, &frames); err = snd_pcm_hw_params_get_channels(hw_params, &channels); bits_per_sample = snd_pcm_format_physical_width(format); bits_per_frame = bits_per_sample * channels; if (TRACE_ON(dsalsa)) ALSA_TraceParameters(hw_params, NULL, FALSE); TRACE("format=%s frames=%ld channels=%d bits_per_sample=%d bits_per_frame=%d\n", snd_pcm_format_name(format), frames, channels, bits_per_sample, bits_per_frame); pdbi->mmap_buflen_frames = frames; pdbi->mmap_buflen_bytes = snd_pcm_frames_to_bytes( pcm, frames ); snd_pcm_sw_params_current(pcm, sw_params); snd_pcm_sw_params_set_start_threshold(pcm, sw_params, 0); snd_pcm_sw_params_get_boundary(sw_params, &boundary); snd_pcm_sw_params_set_stop_threshold(pcm, sw_params, boundary); snd_pcm_sw_params_set_silence_threshold(pcm, sw_params, boundary); snd_pcm_sw_params_set_silence_size(pcm, sw_params, 0); snd_pcm_sw_params_set_avail_min(pcm, sw_params, 0); err = snd_pcm_sw_params(pcm, sw_params); avail = snd_pcm_avail_update(pcm); if ((snd_pcm_sframes_t)avail < 0) { ERR("No buffer is available: %s.\n", snd_strerror(avail)); return DSERR_GENERIC; } if (!pdbi->mmap) { buf = pdbi->mmap_buffer = HeapAlloc(GetProcessHeap(), 0, pdbi->mmap_buflen_bytes); if (!buf) return DSERR_OUTOFMEMORY; snd_pcm_format_set_silence(format, buf, pdbi->mmap_buflen_frames); pdbi->mmap_pos = 0; } else { err = snd_pcm_mmap_begin(pcm, &areas, &ofs, &avail); if ( err < 0 ) { ERR("Can't map sound device for direct access: %s/%d\n", snd_strerror(err), err); return DSERR_GENERIC; } snd_pcm_format_set_silence(format, areas->addr, pdbi->mmap_buflen_frames); pdbi->mmap_pos = ofs + snd_pcm_mmap_commit(pcm, ofs, 0); pdbi->mmap_buffer = areas->addr; } TRACE("created mmap buffer of %ld frames (%d bytes) at %p\n", frames, pdbi->mmap_buflen_bytes, pdbi->mmap_buffer); return DS_OK; }
/* open & setup audio device return: 1=success 0=fail */ static int init(int rate_hz, int channels, int format, int flags) { unsigned int alsa_buffer_time = 500000; /* 0.5 s */ unsigned int alsa_fragcount = 16; int err; int block; strarg_t device; snd_pcm_uframes_t chunk_size; snd_pcm_uframes_t bufsize; snd_pcm_uframes_t boundary; const opt_t subopts[] = { {"block", OPT_ARG_BOOL, &block, NULL}, {"device", OPT_ARG_STR, &device, str_maxlen}, {NULL} }; char alsa_device[ALSA_DEVICE_SIZE + 1]; // make sure alsa_device is null-terminated even when using strncpy etc. memset(alsa_device, 0, ALSA_DEVICE_SIZE + 1); mp_msg(MSGT_AO,MSGL_V,"alsa-init: requested format: %d Hz, %d channels, %x\n", rate_hz, channels, format); alsa_handler = NULL; #if SND_LIB_VERSION >= 0x010005 mp_msg(MSGT_AO,MSGL_V,"alsa-init: using ALSA %s\n", snd_asoundlib_version()); #else mp_msg(MSGT_AO,MSGL_V,"alsa-init: compiled for ALSA-%s\n", SND_LIB_VERSION_STR); #endif snd_lib_error_set_handler(alsa_error_handler); ao_data.samplerate = rate_hz; ao_data.format = format; ao_data.channels = channels; switch (format) { case AF_FORMAT_S8: alsa_format = SND_PCM_FORMAT_S8; break; case AF_FORMAT_U8: alsa_format = SND_PCM_FORMAT_U8; break; case AF_FORMAT_U16_LE: alsa_format = SND_PCM_FORMAT_U16_LE; break; case AF_FORMAT_U16_BE: alsa_format = SND_PCM_FORMAT_U16_BE; break; case AF_FORMAT_AC3_LE: case AF_FORMAT_S16_LE: case AF_FORMAT_IEC61937_LE: alsa_format = SND_PCM_FORMAT_S16_LE; break; case AF_FORMAT_AC3_BE: case AF_FORMAT_S16_BE: case AF_FORMAT_IEC61937_BE: alsa_format = SND_PCM_FORMAT_S16_BE; break; case AF_FORMAT_U32_LE: alsa_format = SND_PCM_FORMAT_U32_LE; break; case AF_FORMAT_U32_BE: alsa_format = SND_PCM_FORMAT_U32_BE; break; case AF_FORMAT_S32_LE: alsa_format = SND_PCM_FORMAT_S32_LE; break; case AF_FORMAT_S32_BE: alsa_format = SND_PCM_FORMAT_S32_BE; break; case AF_FORMAT_U24_LE: alsa_format = SND_PCM_FORMAT_U24_3LE; break; case AF_FORMAT_U24_BE: alsa_format = SND_PCM_FORMAT_U24_3BE; break; case AF_FORMAT_S24_LE: alsa_format = SND_PCM_FORMAT_S24_3LE; break; case AF_FORMAT_S24_BE: alsa_format = SND_PCM_FORMAT_S24_3BE; break; case AF_FORMAT_FLOAT_LE: alsa_format = SND_PCM_FORMAT_FLOAT_LE; break; case AF_FORMAT_FLOAT_BE: alsa_format = SND_PCM_FORMAT_FLOAT_BE; break; case AF_FORMAT_MU_LAW: alsa_format = SND_PCM_FORMAT_MU_LAW; break; case AF_FORMAT_A_LAW: alsa_format = SND_PCM_FORMAT_A_LAW; break; default: alsa_format = SND_PCM_FORMAT_MPEG; //? default should be -1 break; } //subdevice parsing // set defaults block = 1; /* switch for spdif * sets opening sequence for SPDIF * sets also the playback and other switches 'on the fly' * while opening the abstract alias for the spdif subdevice * 'iec958' */ if (AF_FORMAT_IS_IEC61937(format)) { device.str = "iec958"; mp_msg(MSGT_AO,MSGL_V,"alsa-spdif-init: playing AC3/iec61937/iec958, %i channels\n", channels); } else /* in any case for multichannel playback we should select * appropriate device */ switch (channels) { case 1: case 2: device.str = "default"; mp_msg(MSGT_AO,MSGL_V,"alsa-init: setup for 1/2 channel(s)\n"); break; case 4: if (alsa_format == SND_PCM_FORMAT_FLOAT_LE) // hack - use the converter plugin device.str = "plug:surround40"; else device.str = "surround40"; mp_msg(MSGT_AO,MSGL_V,"alsa-init: device set to surround40\n"); break; case 6: if (alsa_format == SND_PCM_FORMAT_FLOAT_LE) device.str = "plug:surround51"; else device.str = "surround51"; mp_msg(MSGT_AO,MSGL_V,"alsa-init: device set to surround51\n"); break; case 8: if (alsa_format == SND_PCM_FORMAT_FLOAT_LE) device.str = "plug:surround71"; else device.str = "surround71"; mp_msg(MSGT_AO,MSGL_V,"alsa-init: device set to surround71\n"); break; default: device.str = "default"; mp_msg(MSGT_AO,MSGL_ERR,MSGTR_AO_ALSA_ChannelsNotSupported,channels); } device.len = strlen(device.str); if (subopt_parse(ao_subdevice, subopts) != 0) { print_help(); return 0; } parse_device(alsa_device, device.str, device.len); mp_msg(MSGT_AO,MSGL_V,"alsa-init: using device %s\n", alsa_device); if (!alsa_handler) { int open_mode = block ? 0 : SND_PCM_NONBLOCK; int isac3 = AF_FORMAT_IS_IEC61937(format); //modes = 0, SND_PCM_NONBLOCK, SND_PCM_ASYNC mp_msg(MSGT_AO,MSGL_V,"alsa-init: opening device in %sblocking mode\n", block ? "" : "non-"); if ((err = try_open_device(alsa_device, open_mode, isac3)) < 0) { if (err != -EBUSY && !block) { mp_msg(MSGT_AO,MSGL_INFO,MSGTR_AO_ALSA_OpenInNonblockModeFailed); if ((err = try_open_device(alsa_device, 0, isac3)) < 0) { mp_msg(MSGT_AO,MSGL_ERR,MSGTR_AO_ALSA_PlaybackOpenError, snd_strerror(err)); return 0; } } else { mp_msg(MSGT_AO,MSGL_ERR,MSGTR_AO_ALSA_PlaybackOpenError, snd_strerror(err)); return 0; } } if ((err = snd_pcm_nonblock(alsa_handler, 0)) < 0) { mp_msg(MSGT_AO,MSGL_ERR,MSGTR_AO_ALSA_ErrorSetBlockMode, snd_strerror(err)); } else { mp_msg(MSGT_AO,MSGL_V,"alsa-init: device reopened in blocking mode\n"); } snd_pcm_hw_params_alloca(&alsa_hwparams); snd_pcm_sw_params_alloca(&alsa_swparams); // setting hw-parameters if ((err = snd_pcm_hw_params_any(alsa_handler, alsa_hwparams)) < 0) { mp_msg(MSGT_AO,MSGL_ERR,MSGTR_AO_ALSA_UnableToGetInitialParameters, snd_strerror(err)); return 0; } err = snd_pcm_hw_params_set_access(alsa_handler, alsa_hwparams, SND_PCM_ACCESS_RW_INTERLEAVED); if (err < 0) { mp_msg(MSGT_AO,MSGL_ERR,MSGTR_AO_ALSA_UnableToSetAccessType, snd_strerror(err)); return 0; } /* workaround for nonsupported formats sets default format to S16_LE if the given formats aren't supported */ if ((err = snd_pcm_hw_params_test_format(alsa_handler, alsa_hwparams, alsa_format)) < 0) { mp_msg(MSGT_AO,MSGL_INFO, MSGTR_AO_ALSA_FormatNotSupportedByHardware, af_fmt2str_short(format)); alsa_format = SND_PCM_FORMAT_S16_LE; if (AF_FORMAT_IS_AC3(ao_data.format)) ao_data.format = AF_FORMAT_AC3_LE; else if (AF_FORMAT_IS_IEC61937(ao_data.format)) ao_data.format = AF_FORMAT_IEC61937_LE; else ao_data.format = AF_FORMAT_S16_LE; } if ((err = snd_pcm_hw_params_set_format(alsa_handler, alsa_hwparams, alsa_format)) < 0) { mp_msg(MSGT_AO,MSGL_ERR,MSGTR_AO_ALSA_UnableToSetFormat, snd_strerror(err)); return 0; } if ((err = snd_pcm_hw_params_set_channels_near(alsa_handler, alsa_hwparams, &ao_data.channels)) < 0) { mp_msg(MSGT_AO,MSGL_ERR,MSGTR_AO_ALSA_UnableToSetChannels, snd_strerror(err)); return 0; } /* workaround for buggy rate plugin (should be fixed in ALSA 1.0.11) prefer our own resampler, since that allows users to choose the resampler, even per file if desired */ #if SND_LIB_VERSION >= 0x010009 if ((err = snd_pcm_hw_params_set_rate_resample(alsa_handler, alsa_hwparams, 0)) < 0) { mp_msg(MSGT_AO,MSGL_ERR,MSGTR_AO_ALSA_UnableToDisableResampling, snd_strerror(err)); return 0; } #endif if ((err = snd_pcm_hw_params_set_rate_near(alsa_handler, alsa_hwparams, &ao_data.samplerate, NULL)) < 0) { mp_msg(MSGT_AO,MSGL_ERR,MSGTR_AO_ALSA_UnableToSetSamplerate2, snd_strerror(err)); return 0; } bytes_per_sample = af_fmt2bits(ao_data.format) / 8; bytes_per_sample *= ao_data.channels; ao_data.bps = ao_data.samplerate * bytes_per_sample; if ((err = snd_pcm_hw_params_set_buffer_time_near(alsa_handler, alsa_hwparams, &alsa_buffer_time, NULL)) < 0) { mp_msg(MSGT_AO,MSGL_ERR,MSGTR_AO_ALSA_UnableToSetBufferTimeNear, snd_strerror(err)); return 0; } if ((err = snd_pcm_hw_params_set_periods_near(alsa_handler, alsa_hwparams, &alsa_fragcount, NULL)) < 0) { mp_msg(MSGT_AO,MSGL_ERR,MSGTR_AO_ALSA_UnableToSetPeriods, snd_strerror(err)); return 0; } /* finally install hardware parameters */ if ((err = snd_pcm_hw_params(alsa_handler, alsa_hwparams)) < 0) { mp_msg(MSGT_AO,MSGL_ERR,MSGTR_AO_ALSA_UnableToSetHwParameters, snd_strerror(err)); return 0; } // end setting hw-params // gets buffersize for control if ((err = snd_pcm_hw_params_get_buffer_size(alsa_hwparams, &bufsize)) < 0) { mp_msg(MSGT_AO,MSGL_ERR,MSGTR_AO_ALSA_UnableToGetBufferSize, snd_strerror(err)); return 0; } else { ao_data.buffersize = bufsize * bytes_per_sample; mp_msg(MSGT_AO,MSGL_V,"alsa-init: got buffersize=%i\n", ao_data.buffersize); } if ((err = snd_pcm_hw_params_get_period_size(alsa_hwparams, &chunk_size, NULL)) < 0) { mp_msg(MSGT_AO,MSGL_ERR,MSGTR_AO_ALSA_UnableToGetPeriodSize, snd_strerror(err)); return 0; } else { mp_msg(MSGT_AO,MSGL_V,"alsa-init: got period size %li\n", chunk_size); } ao_data.outburst = chunk_size * bytes_per_sample; /* setting software parameters */ if ((err = snd_pcm_sw_params_current(alsa_handler, alsa_swparams)) < 0) { mp_msg(MSGT_AO,MSGL_ERR,MSGTR_AO_ALSA_UnableToGetSwParameters, snd_strerror(err)); return 0; } #if SND_LIB_VERSION >= 0x000901 if ((err = snd_pcm_sw_params_get_boundary(alsa_swparams, &boundary)) < 0) { mp_msg(MSGT_AO,MSGL_ERR,MSGTR_AO_ALSA_UnableToGetBoundary, snd_strerror(err)); return 0; } #else boundary = 0x7fffffff; #endif /* start playing when one period has been written */ if ((err = snd_pcm_sw_params_set_start_threshold(alsa_handler, alsa_swparams, chunk_size)) < 0) { mp_msg(MSGT_AO,MSGL_ERR,MSGTR_AO_ALSA_UnableToSetStartThreshold, snd_strerror(err)); return 0; } /* disable underrun reporting */ if ((err = snd_pcm_sw_params_set_stop_threshold(alsa_handler, alsa_swparams, boundary)) < 0) { mp_msg(MSGT_AO,MSGL_ERR,MSGTR_AO_ALSA_UnableToSetStopThreshold, snd_strerror(err)); return 0; } #if SND_LIB_VERSION >= 0x000901 /* play silence when there is an underrun */ if ((err = snd_pcm_sw_params_set_silence_size(alsa_handler, alsa_swparams, boundary)) < 0) { mp_msg(MSGT_AO,MSGL_ERR,MSGTR_AO_ALSA_UnableToSetSilenceSize, snd_strerror(err)); return 0; } #endif if ((err = snd_pcm_sw_params(alsa_handler, alsa_swparams)) < 0) { mp_msg(MSGT_AO,MSGL_ERR,MSGTR_AO_ALSA_UnableToGetSwParameters, snd_strerror(err)); return 0; } /* end setting sw-params */ mp_msg(MSGT_AO,MSGL_V,"alsa: %d Hz/%d channels/%d bpf/%d bytes buffer/%s\n", ao_data.samplerate, ao_data.channels, (int)bytes_per_sample, ao_data.buffersize, snd_pcm_format_description(alsa_format)); } // end switch alsa_handler (spdif) alsa_can_pause = snd_pcm_hw_params_can_pause(alsa_hwparams); return 1; } // end init
/* setup alsa data transfer behavior */ static inline int alsa_set_swparams(ao_device *device) { ao_alsa_internal *internal = (ao_alsa_internal *) device->internal; snd_pcm_sw_params_t *params; snd_pcm_uframes_t boundary; int err; /* allocate the software parameter structure */ snd_pcm_sw_params_alloca(¶ms); /* fetch the current software parameters */ err = snd_pcm_sw_params_current(internal->pcm_handle, params); if (err < 0){ adebug("snd_pcm_sw_params_current() failed.\n"); return err; } #if 0 /* the below causes more trouble than it cures */ /* allow transfers to start when there is one period */ err = snd_pcm_sw_params_set_start_threshold(internal->pcm_handle, params, internal->period_size); if (err < 0){ adebug("snd_pcm_sw_params_set_start_threshold() failed.\n"); //return err; } /* require a minimum of one full transfer in the buffer */ err = snd_pcm_sw_params_set_avail_min(internal->pcm_handle, params, internal->period_size); if (err < 0){ adebug("snd_pcm_sw_params_set_avail_min() failed.\n"); //return err; } #endif /* do not align transfers; this is obsolete/deprecated in ALSA 1.x where the transfer alignemnt is always 1 (except for buggy drivers like VIA 82xx which still demand aligned transfers regardless of setting, in violation of the ALSA API docs) */ err = snd_pcm_sw_params_set_xfer_align(internal->pcm_handle, params, 1); if (err < 0){ adebug("snd_pcm_sw_params_set_xfer_align() failed.\n"); //return err; } /* get the boundary size */ err = snd_pcm_sw_params_get_boundary(params,&boundary); if (err < 0){ adebug("snd_pcm_sw_params_get_boundary() failed.\n"); }else{ /* force a work-ahead silence buffer; this is a fix, again for VIA 82xx, where non-MMIO transfers will buffer into period-size transfers, but the last transfer is usually undersized and playback falls off the end of the submitted data. */ err = snd_pcm_sw_params_set_silence_size(internal->pcm_handle, params, boundary); if (err < 0){ adebug("snd_pcm_sw_params_set_silence_size() failed.\n"); //return err; } } /* commit the params structure to ALSA */ err = snd_pcm_sw_params(internal->pcm_handle, params); if (err < 0){ adebug("snd_pcm_sw_params() failed.\n"); return err; } return 1; }
static int sndo_pcm_initialize(sndo_pcm_t *pcm) { int err; snd_pcm_uframes_t boundary; snd_pcm_uframes_t p_period_size = ~0UL, c_period_size = ~0UL; snd_pcm_uframes_t p_buffer_size = ~0UL, c_buffer_size = ~0UL; if (pcm->playback) { err = snd_pcm_hw_params(pcm->playback, pcm->p_hw_params); if (err < 0) return err; err = snd_pcm_hw_params_get_period_size(pcm->p_hw_params, &p_period_size, NULL); if (err < 0) return err; err = snd_pcm_hw_params_get_buffer_size(pcm->p_hw_params, &p_buffer_size); if (err < 0) return err; } if (pcm->capture) { err = snd_pcm_hw_params(pcm->capture, pcm->c_hw_params); if (err < 0) return err; err = snd_pcm_hw_params_get_period_size(pcm->c_hw_params, &c_period_size, NULL); if (err < 0) return err; err = snd_pcm_hw_params_get_buffer_size(pcm->c_hw_params, &c_buffer_size); if (err < 0) return err; } if (p_period_size < c_period_size) pcm->transfer_block = p_period_size; else pcm->transfer_block = c_period_size; if (p_buffer_size < c_buffer_size) pcm->ring_size = p_buffer_size; else pcm->ring_size = c_buffer_size; if (pcm->playback) { err = snd_pcm_sw_params_get_boundary(pcm->p_sw_params, &boundary); if (err < 0) return err; err = snd_pcm_sw_params_set_start_threshold(pcm->playback, pcm->p_sw_params, boundary); if (err < 0) return err; err = snd_pcm_sw_params_set_stop_threshold(pcm->playback, pcm->p_sw_params, pcm->xrun == SNDO_PCM_XRUN_IGNORE ? boundary : pcm->ring_size); if (err < 0) return err; err = snd_pcm_sw_params_set_xfer_align(pcm->playback, pcm->p_sw_params, 1); if (err < 0) return err; err = snd_pcm_sw_params_set_avail_min(pcm->playback, pcm->p_sw_params, pcm->transfer_block); if (err < 0) return err; err = snd_pcm_sw_params(pcm->playback, pcm->p_sw_params); if (err < 0) return err; } if (pcm->capture) { err = snd_pcm_sw_params_get_boundary(pcm->c_sw_params, &boundary); if (err < 0) return err; err = snd_pcm_sw_params_set_start_threshold(pcm->capture, pcm->c_sw_params, boundary); if (err < 0) return err; err = snd_pcm_sw_params_set_stop_threshold(pcm->capture, pcm->c_sw_params, pcm->xrun == SNDO_PCM_XRUN_IGNORE ? boundary : pcm->ring_size); if (err < 0) return err; err = snd_pcm_sw_params_set_xfer_align(pcm->capture, pcm->c_sw_params, 1); if (err < 0) return err; err = snd_pcm_sw_params_set_avail_min(pcm->capture, pcm->c_sw_params, pcm->transfer_block); if (err < 0) return err; err = snd_pcm_sw_params(pcm->capture, pcm->c_sw_params); if (err < 0) return err; } pcm->initialized = 1; return 0; }
bool setParameters (unsigned int sampleRate, int numChannels, int bufferSize) { if (handle == 0) return false; snd_pcm_hw_params_t* hwParams; snd_pcm_hw_params_alloca (&hwParams); if (failed (snd_pcm_hw_params_any (handle, hwParams))) return false; if (snd_pcm_hw_params_set_access (handle, hwParams, SND_PCM_ACCESS_RW_NONINTERLEAVED) >= 0) isInterleaved = false; else if (snd_pcm_hw_params_set_access (handle, hwParams, SND_PCM_ACCESS_RW_INTERLEAVED) >= 0) isInterleaved = true; else { jassertfalse; return false; } enum { isFloatBit = 1 << 16, isLittleEndianBit = 1 << 17 }; const int formatsToTry[] = { SND_PCM_FORMAT_FLOAT_LE, 32 | isFloatBit | isLittleEndianBit, SND_PCM_FORMAT_FLOAT_BE, 32 | isFloatBit, SND_PCM_FORMAT_S32_LE, 32 | isLittleEndianBit, SND_PCM_FORMAT_S32_BE, 32, SND_PCM_FORMAT_S24_3LE, 24 | isLittleEndianBit, SND_PCM_FORMAT_S24_3BE, 24, SND_PCM_FORMAT_S16_LE, 16 | isLittleEndianBit, SND_PCM_FORMAT_S16_BE, 16 }; bitDepth = 0; for (int i = 0; i < numElementsInArray (formatsToTry); i += 2) { if (snd_pcm_hw_params_set_format (handle, hwParams, (_snd_pcm_format) formatsToTry [i]) >= 0) { bitDepth = formatsToTry [i + 1] & 255; const bool isFloat = (formatsToTry [i + 1] & isFloatBit) != 0; const bool isLittleEndian = (formatsToTry [i + 1] & isLittleEndianBit) != 0; converter = createConverter (isInput, bitDepth, isFloat, isLittleEndian, numChannels); break; } } if (bitDepth == 0) { error = "device doesn't support a compatible PCM format"; DBG ("ALSA error: " + error + "\n"); return false; } int dir = 0; unsigned int periods = 4; snd_pcm_uframes_t samplesPerPeriod = bufferSize; if (failed (snd_pcm_hw_params_set_rate_near (handle, hwParams, &sampleRate, 0)) || failed (snd_pcm_hw_params_set_channels (handle, hwParams, numChannels)) || failed (snd_pcm_hw_params_set_periods_near (handle, hwParams, &periods, &dir)) || failed (snd_pcm_hw_params_set_period_size_near (handle, hwParams, &samplesPerPeriod, &dir)) || failed (snd_pcm_hw_params (handle, hwParams))) { return false; } snd_pcm_uframes_t frames = 0; if (failed (snd_pcm_hw_params_get_period_size (hwParams, &frames, &dir)) || failed (snd_pcm_hw_params_get_periods (hwParams, &periods, &dir))) latency = 0; else latency = frames * (periods - 1); // (this is the method JACK uses to guess the latency..) snd_pcm_sw_params_t* swParams; snd_pcm_sw_params_alloca (&swParams); snd_pcm_uframes_t boundary; if (failed (snd_pcm_sw_params_current (handle, swParams)) || failed (snd_pcm_sw_params_get_boundary (swParams, &boundary)) || failed (snd_pcm_sw_params_set_silence_threshold (handle, swParams, 0)) || failed (snd_pcm_sw_params_set_silence_size (handle, swParams, boundary)) || failed (snd_pcm_sw_params_set_start_threshold (handle, swParams, samplesPerPeriod)) || failed (snd_pcm_sw_params_set_stop_threshold (handle, swParams, boundary)) || failed (snd_pcm_sw_params (handle, swParams))) { return false; } #if 0 // enable this to dump the config of the devices that get opened snd_output_t* out; snd_output_stdio_attach (&out, stderr, 0); snd_pcm_hw_params_dump (hwParams, out); snd_pcm_sw_params_dump (swParams, out); #endif numChannelsRunning = numChannels; return true; }