1 #include "alsa_input.h"
3 #include <alsa/error.h>
10 #include "alsa_pool.h"
11 #include "bmusb/bmusb.h"
15 using namespace std::placeholders;
17 #define RETURN_ON_ERROR(msg, expr) do { \
20 fprintf(stderr, "[%s] " msg ": %s\n", device.c_str(), snd_strerror(err)); \
21 if (err == -ENODEV) return CaptureEndReason::DEVICE_GONE; \
22 return CaptureEndReason::OTHER_ERROR; \
26 #define RETURN_FALSE_ON_ERROR(msg, expr) do { \
29 fprintf(stderr, "[%s] " msg ": %s\n", device.c_str(), snd_strerror(err)); \
34 #define WARN_ON_ERROR(msg, expr) do { \
37 fprintf(stderr, "[%s] " msg ": %s\n", device.c_str(), snd_strerror(err)); \
41 ALSAInput::ALSAInput(const char *device, unsigned sample_rate, unsigned num_channels, audio_callback_t audio_callback, ALSAPool *parent_pool, unsigned internal_dev_index)
43 sample_rate(sample_rate),
44 num_channels(num_channels),
45 audio_callback(audio_callback),
46 parent_pool(parent_pool),
47 internal_dev_index(internal_dev_index)
51 bool ALSAInput::open_device()
53 RETURN_FALSE_ON_ERROR("snd_pcm_open()", snd_pcm_open(&pcm_handle, device.c_str(), SND_PCM_STREAM_CAPTURE, 0));
56 snd_pcm_hw_params_t *hw_params;
57 snd_pcm_hw_params_alloca(&hw_params);
58 if (!set_base_params(device.c_str(), pcm_handle, hw_params, &sample_rate)) {
62 RETURN_FALSE_ON_ERROR("snd_pcm_hw_params_set_channels()", snd_pcm_hw_params_set_channels(pcm_handle, hw_params, num_channels));
64 // Fragment size of 64 samples (about 1 ms at 48 kHz; a frame at 60
65 // fps/48 kHz is 800 samples.) We ask for 64 such periods in our buffer
66 // (~85 ms buffer); more than that, and our jitter is probably so high
67 // that the resampling queue can't keep up anyway.
68 // The entire thing with periods and such is a bit mysterious to me;
69 // seemingly I can get 96 frames at a time with no problems even if
70 // the period size is 64 frames. And if I set num_periods to e.g. 1,
71 // I can't have a big buffer.
74 RETURN_FALSE_ON_ERROR("snd_pcm_hw_params_set_periods_near()", snd_pcm_hw_params_set_periods_near(pcm_handle, hw_params, &num_periods, &dir));
77 RETURN_FALSE_ON_ERROR("snd_pcm_hw_params_set_period_size_near()", snd_pcm_hw_params_set_period_size_near(pcm_handle, hw_params, &period_size, &dir));
78 buffer_frames = 64 * 64;
79 RETURN_FALSE_ON_ERROR("snd_pcm_hw_params_set_buffer_size_near()", snd_pcm_hw_params_set_buffer_size_near(pcm_handle, hw_params, &buffer_frames));
80 RETURN_FALSE_ON_ERROR("snd_pcm_hw_params()", snd_pcm_hw_params(pcm_handle, hw_params));
81 //snd_pcm_hw_params_free(hw_params);
83 // Figure out which format the card actually chose.
84 RETURN_FALSE_ON_ERROR("snd_pcm_hw_params_current()", snd_pcm_hw_params_current(pcm_handle, hw_params));
85 snd_pcm_format_t chosen_format;
86 RETURN_FALSE_ON_ERROR("snd_pcm_hw_params_get_format()", snd_pcm_hw_params_get_format(hw_params, &chosen_format));
88 audio_format.num_channels = num_channels;
89 audio_format.bits_per_sample = 0;
90 switch (chosen_format) {
91 case SND_PCM_FORMAT_S16_LE:
92 audio_format.bits_per_sample = 16;
94 case SND_PCM_FORMAT_S24_LE:
95 audio_format.bits_per_sample = 24;
97 case SND_PCM_FORMAT_S32_LE:
98 audio_format.bits_per_sample = 32;
103 //printf("num_periods=%u period_size=%u buffer_frames=%u sample_rate=%u bits_per_sample=%d\n",
104 // num_periods, unsigned(period_size), unsigned(buffer_frames), sample_rate, audio_format.bits_per_sample);
106 buffer.reset(new uint8_t[buffer_frames * num_channels * audio_format.bits_per_sample / 8]);
108 snd_pcm_sw_params_t *sw_params;
109 snd_pcm_sw_params_alloca(&sw_params);
110 RETURN_FALSE_ON_ERROR("snd_pcm_sw_params_current()", snd_pcm_sw_params_current(pcm_handle, sw_params));
111 RETURN_FALSE_ON_ERROR("snd_pcm_sw_params_set_start_threshold", snd_pcm_sw_params_set_start_threshold(pcm_handle, sw_params, num_periods * period_size / 2));
112 RETURN_FALSE_ON_ERROR("snd_pcm_sw_params()", snd_pcm_sw_params(pcm_handle, sw_params));
114 RETURN_FALSE_ON_ERROR("snd_pcm_nonblock()", snd_pcm_nonblock(pcm_handle, 1));
115 RETURN_FALSE_ON_ERROR("snd_pcm_prepare()", snd_pcm_prepare(pcm_handle));
119 bool ALSAInput::set_base_params(const char *device_name, snd_pcm_t *pcm_handle, snd_pcm_hw_params_t *hw_params, unsigned *sample_rate)
122 err = snd_pcm_hw_params_any(pcm_handle, hw_params);
124 fprintf(stderr, "[%s] snd_pcm_hw_params_any(): %s\n", device_name, snd_strerror(err));
127 err = snd_pcm_hw_params_set_access(pcm_handle, hw_params, SND_PCM_ACCESS_RW_INTERLEAVED);
129 fprintf(stderr, "[%s] snd_pcm_hw_params_set_access(): %s\n", device_name, snd_strerror(err));
132 snd_pcm_format_mask_t *format_mask;
133 snd_pcm_format_mask_alloca(&format_mask);
134 snd_pcm_format_mask_set(format_mask, SND_PCM_FORMAT_S16_LE);
135 snd_pcm_format_mask_set(format_mask, SND_PCM_FORMAT_S24_LE);
136 snd_pcm_format_mask_set(format_mask, SND_PCM_FORMAT_S32_LE);
137 err = snd_pcm_hw_params_set_format_mask(pcm_handle, hw_params, format_mask);
139 fprintf(stderr, "[%s] snd_pcm_hw_params_set_format_mask(): %s\n", device_name, snd_strerror(err));
142 err = snd_pcm_hw_params_set_rate_near(pcm_handle, hw_params, sample_rate, 0);
144 fprintf(stderr, "[%s] snd_pcm_hw_params_set_rate_near(): %s\n", device_name, snd_strerror(err));
150 ALSAInput::~ALSAInput()
153 WARN_ON_ERROR("snd_pcm_close()", snd_pcm_close(pcm_handle));
157 void ALSAInput::start_capture_thread()
160 capture_thread = thread(&ALSAInput::capture_thread_func, this);
163 void ALSAInput::stop_capture_thread()
166 capture_thread.join();
169 void ALSAInput::capture_thread_func()
171 parent_pool->set_card_state(internal_dev_index, ALSAPool::Device::State::STARTING);
173 // If the device hasn't been opened already, we need to do so
174 // before we can capture.
175 while (!should_quit && pcm_handle == nullptr) {
176 if (!open_device()) {
177 fprintf(stderr, "[%s] Waiting one second and trying again...\n",
184 // Don't call free_card(); that would be a deadlock.
185 WARN_ON_ERROR("snd_pcm_close()", snd_pcm_close(pcm_handle));
186 pcm_handle = nullptr;
190 // Do the actual capture. (Termination condition within loop.)
192 switch (do_capture()) {
193 case CaptureEndReason::REQUESTED_QUIT:
194 // Don't call free_card(); that would be a deadlock.
195 WARN_ON_ERROR("snd_pcm_close()", snd_pcm_close(pcm_handle));
196 pcm_handle = nullptr;
198 case CaptureEndReason::DEVICE_GONE:
199 parent_pool->free_card(internal_dev_index);
200 WARN_ON_ERROR("snd_pcm_close()", snd_pcm_close(pcm_handle));
201 pcm_handle = nullptr;
203 case CaptureEndReason::OTHER_ERROR:
204 parent_pool->set_card_state(internal_dev_index, ALSAPool::Device::State::STARTING);
205 fprintf(stderr, "[%s] Sleeping one second and restarting capture...\n",
213 ALSAInput::CaptureEndReason ALSAInput::do_capture()
215 parent_pool->set_card_state(internal_dev_index, ALSAPool::Device::State::STARTING);
216 RETURN_ON_ERROR("snd_pcm_start()", snd_pcm_start(pcm_handle));
217 parent_pool->set_card_state(internal_dev_index, ALSAPool::Device::State::RUNNING);
219 uint64_t num_frames_output = 0;
220 while (!should_quit) {
221 int ret = snd_pcm_wait(pcm_handle, /*timeout=*/100);
222 if (ret == 0) continue; // Timeout.
224 fprintf(stderr, "[%s] ALSA overrun\n", device.c_str());
225 snd_pcm_prepare(pcm_handle);
226 snd_pcm_start(pcm_handle);
229 RETURN_ON_ERROR("snd_pcm_wait()", ret);
231 snd_pcm_sframes_t frames = snd_pcm_readi(pcm_handle, buffer.get(), buffer_frames);
232 if (frames == -EPIPE) {
233 fprintf(stderr, "[%s] ALSA overrun\n", device.c_str());
234 snd_pcm_prepare(pcm_handle);
235 snd_pcm_start(pcm_handle);
239 fprintf(stderr, "snd_pcm_readi() returned 0\n");
242 RETURN_ON_ERROR("snd_pcm_readi()", frames);
244 const int64_t prev_pts = frames_to_pts(num_frames_output);
245 const int64_t pts = frames_to_pts(num_frames_output + frames);
248 if (should_quit) return CaptureEndReason::REQUESTED_QUIT;
249 success = audio_callback(buffer.get(), frames, audio_format, pts - prev_pts);
251 num_frames_output += frames;
253 return CaptureEndReason::REQUESTED_QUIT;
256 int64_t ALSAInput::frames_to_pts(uint64_t n) const
258 return (n * TIMEBASE) / sample_rate;