git.sesse.net Git - nageru/blob - alsa_input.cpp

   1 #include "alsa_input.h"
   2
   3 #include <alsa/error.h>
   4 #include <assert.h>
   5 #include <errno.h>
   6 #include <stdio.h>
   7 #include <unistd.h>
   8 #include <cstdint>
   9
  10 #include "alsa_pool.h"
  11 #include "bmusb/bmusb.h"
  12 #include "timebase.h"
  13
  14 using namespace std;
  15 using namespace std::placeholders;
  16
  17 #define RETURN_ON_ERROR(msg, expr) do {                                                    \
  18         int err = (expr);                                                                  \
  19         if (err < 0) {                                                                     \
  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;                                      \
  23         }                                                                                  \
  24 } while (false)
  25
  26 #define RETURN_FALSE_ON_ERROR(msg, expr) do {                                              \
  27         int err = (expr);                                                                  \
  28         if (err < 0) {                                                                     \
  29                 fprintf(stderr, "[%s] " msg ": %s\n", device.c_str(), snd_strerror(err));  \
  30                 return false;                                                              \
  31         }                                                                                  \
  32 } while (false)
  33
  34 #define WARN_ON_ERROR(msg, expr) do {                                                      \
  35         int err = (expr);                                                                  \
  36         if (err < 0) {                                                                     \
  37                 fprintf(stderr, "[%s] " msg ": %s\n", device.c_str(), snd_strerror(err));  \
  38         }                                                                                  \
  39 } while (false)
  40
  41 ALSAInput::ALSAInput(const char *device, unsigned sample_rate, unsigned num_channels, audio_callback_t audio_callback, ALSAPool *parent_pool, unsigned internal_dev_index)
  42         : device(device),
  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)
  48 {
  49 }
  50
  51 bool ALSAInput::open_device()
  52 {
  53         RETURN_FALSE_ON_ERROR("snd_pcm_open()", snd_pcm_open(&pcm_handle, device.c_str(), SND_PCM_STREAM_CAPTURE, 0));
  54
  55         // Set format.
  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)) {
  59                 return false;
  60         }
  61
  62         RETURN_FALSE_ON_ERROR("snd_pcm_hw_params_set_channels()", snd_pcm_hw_params_set_channels(pcm_handle, hw_params, num_channels));
  63
  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.
  72         num_periods = 16;
  73         int dir = 0;
  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));
  75         period_size = 64;
  76         dir = 0;
  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);
  82
  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));
  87
  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;
  93                 break;
  94         case SND_PCM_FORMAT_S24_LE:
  95                 audio_format.bits_per_sample = 24;
  96                 break;
  97         case SND_PCM_FORMAT_S32_LE:
  98                 audio_format.bits_per_sample = 32;
  99                 break;
 100         default:
 101                 assert(false);
 102         }
 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);
 105
 106         buffer.reset(new uint8_t[buffer_frames * num_channels * audio_format.bits_per_sample / 8]);
 107
 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));
 113
 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));
 116         return true;
 117 }
 118
 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)
 120 {
 121         int err;
 122         err = snd_pcm_hw_params_any(pcm_handle, hw_params);
 123         if (err < 0) {
 124                 fprintf(stderr, "[%s] snd_pcm_hw_params_any(): %s\n", device_name, snd_strerror(err));
 125                 return false;
 126         }
 127         err = snd_pcm_hw_params_set_access(pcm_handle, hw_params, SND_PCM_ACCESS_RW_INTERLEAVED);
 128         if (err < 0) {
 129                 fprintf(stderr, "[%s] snd_pcm_hw_params_set_access(): %s\n", device_name, snd_strerror(err));
 130                 return false;
 131         }
 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);
 138         if (err < 0) {
 139                 fprintf(stderr, "[%s] snd_pcm_hw_params_set_format_mask(): %s\n", device_name, snd_strerror(err));
 140                 return false;
 141         }
 142         err = snd_pcm_hw_params_set_rate_near(pcm_handle, hw_params, sample_rate, 0);
 143         if (err < 0) {
 144                 fprintf(stderr, "[%s] snd_pcm_hw_params_set_rate_near(): %s\n", device_name, snd_strerror(err));
 145                 return false;
 146         }
 147         return true;
 148 }
 149
 150 ALSAInput::~ALSAInput()
 151 {
 152         if (pcm_handle) {
 153                 WARN_ON_ERROR("snd_pcm_close()", snd_pcm_close(pcm_handle));
 154         }
 155 }
 156
 157 void ALSAInput::start_capture_thread()
 158 {
 159         should_quit = false;
 160         capture_thread = thread(&ALSAInput::capture_thread_func, this);
 161 }
 162
 163 void ALSAInput::stop_capture_thread()
 164 {
 165         should_quit = true;
 166         capture_thread.join();
 167 }
 168
 169 void ALSAInput::capture_thread_func()
 170 {
 171         parent_pool->set_card_state(internal_dev_index, ALSAPool::Device::State::STARTING);
 172
 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",
 178                                 device.c_str());
 179                         sleep(1);
 180                 }
 181         }
 182
 183         if (should_quit) {
 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;
 187                 return;
 188         }
 189
 190         // Do the actual capture. (Termination condition within loop.)
 191         for ( ;; ) {
 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;
 197                         return;
 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;
 202                         return;
 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",
 206                                 device.c_str());
 207                         sleep(1);
 208                         break;
 209                 }
 210         }
 211 }
 212
 213 ALSAInput::CaptureEndReason ALSAInput::do_capture()
 214 {
 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);
 218
 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.
 223                 if (ret == -EPIPE) {
 224                         fprintf(stderr, "[%s] ALSA overrun\n", device.c_str());
 225                         snd_pcm_prepare(pcm_handle);
 226                         snd_pcm_start(pcm_handle);
 227                         continue;
 228                 }
 229                 RETURN_ON_ERROR("snd_pcm_wait()", ret);
 230
 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);
 236                         continue;
 237                 }
 238                 if (frames == 0) {
 239                         fprintf(stderr, "snd_pcm_readi() returned 0\n");
 240                         break;
 241                 }
 242                 RETURN_ON_ERROR("snd_pcm_readi()", frames);
 243
 244                 const int64_t prev_pts = frames_to_pts(num_frames_output);
 245                 const int64_t pts = frames_to_pts(num_frames_output + frames);
 246                 bool success;
 247                 do {
 248                         if (should_quit) return CaptureEndReason::REQUESTED_QUIT;
 249                         success = audio_callback(buffer.get(), frames, audio_format, pts - prev_pts);
 250                 } while (!success);
 251                 num_frames_output += frames;
 252         }
 253         return CaptureEndReason::REQUESTED_QUIT;
 254 }
 255
 256 int64_t ALSAInput::frames_to_pts(uint64_t n) const
 257 {
 258         return (n * TIMEBASE) / sample_rate;
 259 }
 260