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

   1 #include "alsa_input.h"
   2 #include "audio_mixer.h"
   3 #include "defs.h"
   4 #include "state.pb.h"
   5
   6 #include <sys/inotify.h>
   7
   8 #include <algorithm>
   9 #include <functional>
  10 #include <unordered_map>
  11
  12 using namespace std;
  13 using namespace std::placeholders;
  14
  15 namespace {
  16
  17 bool set_base_params(const char *device_name, snd_pcm_t *pcm_handle, snd_pcm_hw_params_t *hw_params, unsigned *sample_rate)
  18 {
  19         int err;
  20         err = snd_pcm_hw_params_any(pcm_handle, hw_params);
  21         if (err < 0) {
  22                 fprintf(stderr, "[%s] snd_pcm_hw_params_any(): %s\n", device_name, snd_strerror(err));
  23                 return false;
  24         }
  25         err = snd_pcm_hw_params_set_access(pcm_handle, hw_params, SND_PCM_ACCESS_RW_INTERLEAVED);
  26         if (err < 0) {
  27                 fprintf(stderr, "[%s] snd_pcm_hw_params_set_access(): %s\n", device_name, snd_strerror(err));
  28                 return false;
  29         }
  30         snd_pcm_format_mask_t *format_mask;
  31         snd_pcm_format_mask_alloca(&format_mask);
  32         snd_pcm_format_mask_set(format_mask, SND_PCM_FORMAT_S16_LE);
  33         snd_pcm_format_mask_set(format_mask, SND_PCM_FORMAT_S24_LE);
  34         snd_pcm_format_mask_set(format_mask, SND_PCM_FORMAT_S32_LE);
  35         err = snd_pcm_hw_params_set_format_mask(pcm_handle, hw_params, format_mask);
  36         if (err < 0) {
  37                 fprintf(stderr, "[%s] snd_pcm_hw_params_set_format_mask(): %s\n", device_name, snd_strerror(err));
  38                 return false;
  39         }
  40         err = snd_pcm_hw_params_set_rate_near(pcm_handle, hw_params, sample_rate, 0);
  41         if (err < 0) {
  42                 fprintf(stderr, "[%s] snd_pcm_hw_params_set_rate_near(): %s\n", device_name, snd_strerror(err));
  43                 return false;
  44         }
  45         return true;
  46 }
  47
  48 }  // namespace
  49
  50 #define RETURN_ON_ERROR(msg, expr) do {                                                    \
  51         int err = (expr);                                                                  \
  52         if (err < 0) {                                                                     \
  53                 fprintf(stderr, "[%s] " msg ": %s\n", device.c_str(), snd_strerror(err));  \
  54                 if (err == -ENODEV) return CaptureEndReason::DEVICE_GONE;                  \
  55                 return CaptureEndReason::OTHER_ERROR;                                      \
  56         }                                                                                  \
  57 } while (false)
  58
  59 #define RETURN_FALSE_ON_ERROR(msg, expr) do {                                              \
  60         int err = (expr);                                                                  \
  61         if (err < 0) {                                                                     \
  62                 fprintf(stderr, "[%s] " msg ": %s\n", device.c_str(), snd_strerror(err));  \
  63                 return false;                                                              \
  64         }                                                                                  \
  65 } while (false)
  66
  67 #define WARN_ON_ERROR(msg, expr) do {                                                      \
  68         int err = (expr);                                                                  \
  69         if (err < 0) {                                                                     \
  70                 fprintf(stderr, "[%s] " msg ": %s\n", device.c_str(), snd_strerror(err));  \
  71         }                                                                                  \
  72 } while (false)
  73
  74 ALSAInput::ALSAInput(const char *device, unsigned sample_rate, unsigned num_channels, audio_callback_t audio_callback, ALSAPool *parent_pool, unsigned internal_dev_index)
  75         : device(device),
  76           sample_rate(sample_rate),
  77           num_channels(num_channels),
  78           audio_callback(audio_callback),
  79           parent_pool(parent_pool),
  80           internal_dev_index(internal_dev_index)
  81 {
  82 }
  83
  84 bool ALSAInput::open_device()
  85 {
  86         RETURN_FALSE_ON_ERROR("snd_pcm_open()", snd_pcm_open(&pcm_handle, device.c_str(), SND_PCM_STREAM_CAPTURE, 0));
  87
  88         // Set format.
  89         snd_pcm_hw_params_t *hw_params;
  90         snd_pcm_hw_params_alloca(&hw_params);
  91         if (!set_base_params(device.c_str(), pcm_handle, hw_params, &sample_rate)) {
  92                 return false;
  93         }
  94
  95         RETURN_FALSE_ON_ERROR("snd_pcm_hw_params_set_channels()", snd_pcm_hw_params_set_channels(pcm_handle, hw_params, num_channels));
  96
  97         // Fragment size of 64 samples (about 1 ms at 48 kHz; a frame at 60
  98         // fps/48 kHz is 800 samples.) We ask for 64 such periods in our buffer
  99         // (~85 ms buffer); more than that, and our jitter is probably so high
 100         // that the resampling queue can't keep up anyway.
 101         // The entire thing with periods and such is a bit mysterious to me;
 102         // seemingly I can get 96 frames at a time with no problems even if
 103         // the period size is 64 frames. And if I set num_periods to e.g. 1,
 104         // I can't have a big buffer.
 105         num_periods = 16;
 106         int dir = 0;
 107         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));
 108         period_size = 64;
 109         dir = 0;
 110         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));
 111         buffer_frames = 64 * 64;
 112         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));
 113         RETURN_FALSE_ON_ERROR("snd_pcm_hw_params()", snd_pcm_hw_params(pcm_handle, hw_params));
 114         //snd_pcm_hw_params_free(hw_params);
 115
 116         // Figure out which format the card actually chose.
 117         RETURN_FALSE_ON_ERROR("snd_pcm_hw_params_current()", snd_pcm_hw_params_current(pcm_handle, hw_params));
 118         snd_pcm_format_t chosen_format;
 119         RETURN_FALSE_ON_ERROR("snd_pcm_hw_params_get_format()", snd_pcm_hw_params_get_format(hw_params, &chosen_format));
 120
 121         audio_format.num_channels = num_channels;
 122         audio_format.bits_per_sample = 0;
 123         switch (chosen_format) {
 124         case SND_PCM_FORMAT_S16_LE:
 125                 audio_format.bits_per_sample = 16;
 126                 break;
 127         case SND_PCM_FORMAT_S24_LE:
 128                 audio_format.bits_per_sample = 24;
 129                 break;
 130         case SND_PCM_FORMAT_S32_LE:
 131                 audio_format.bits_per_sample = 32;
 132                 break;
 133         default:
 134                 assert(false);
 135         }
 136         //printf("num_periods=%u period_size=%u buffer_frames=%u sample_rate=%u bits_per_sample=%d\n",
 137         //      num_periods, unsigned(period_size), unsigned(buffer_frames), sample_rate, audio_format.bits_per_sample);
 138
 139         buffer.reset(new uint8_t[buffer_frames * num_channels * audio_format.bits_per_sample / 8]);
 140
 141         snd_pcm_sw_params_t *sw_params;
 142         snd_pcm_sw_params_alloca(&sw_params);
 143         RETURN_FALSE_ON_ERROR("snd_pcm_sw_params_current()", snd_pcm_sw_params_current(pcm_handle, sw_params));
 144         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));
 145         RETURN_FALSE_ON_ERROR("snd_pcm_sw_params()", snd_pcm_sw_params(pcm_handle, sw_params));
 146
 147         RETURN_FALSE_ON_ERROR("snd_pcm_nonblock()", snd_pcm_nonblock(pcm_handle, 1));
 148         RETURN_FALSE_ON_ERROR("snd_pcm_prepare()", snd_pcm_prepare(pcm_handle));
 149         return true;
 150 }
 151
 152 ALSAInput::~ALSAInput()
 153 {
 154         if (pcm_handle) {
 155                 WARN_ON_ERROR("snd_pcm_close()", snd_pcm_close(pcm_handle));
 156         }
 157 }
 158
 159 void ALSAInput::start_capture_thread()
 160 {
 161         should_quit = false;
 162         capture_thread = thread(&ALSAInput::capture_thread_func, this);
 163 }
 164
 165 void ALSAInput::stop_capture_thread()
 166 {
 167         should_quit = true;
 168         capture_thread.join();
 169 }
 170
 171 void ALSAInput::capture_thread_func()
 172 {
 173         parent_pool->set_card_state(internal_dev_index, ALSAPool::Device::State::STARTING);
 174
 175         // If the device hasn't been opened already, we need to do so
 176         // before we can capture.
 177         while (!should_quit && pcm_handle == nullptr) {
 178                 if (!open_device()) {
 179                         fprintf(stderr, "[%s] Waiting one second and trying again...\n",
 180                                 device.c_str());
 181                         sleep(1);
 182                 }
 183         }
 184
 185         if (should_quit) {
 186                 // Don't call free_card(); that would be a deadlock.
 187                 WARN_ON_ERROR("snd_pcm_close()", snd_pcm_close(pcm_handle));
 188                 pcm_handle = nullptr;
 189                 return;
 190         }
 191
 192         // Do the actual capture. (Termination condition within loop.)
 193         for ( ;; ) {
 194                 switch (do_capture()) {
 195                 case CaptureEndReason::REQUESTED_QUIT:
 196                         // Don't call free_card(); that would be a deadlock.
 197                         WARN_ON_ERROR("snd_pcm_close()", snd_pcm_close(pcm_handle));
 198                         pcm_handle = nullptr;
 199                         return;
 200                 case CaptureEndReason::DEVICE_GONE:
 201                         parent_pool->free_card(internal_dev_index);
 202                         WARN_ON_ERROR("snd_pcm_close()", snd_pcm_close(pcm_handle));
 203                         pcm_handle = nullptr;
 204                         return;
 205                 case CaptureEndReason::OTHER_ERROR:
 206                         parent_pool->set_card_state(internal_dev_index, ALSAPool::Device::State::STARTING);
 207                         fprintf(stderr, "[%s] Sleeping one second and restarting capture...\n",
 208                                 device.c_str());
 209                         sleep(1);
 210                         break;
 211                 }
 212         }
 213 }
 214
 215 ALSAInput::CaptureEndReason ALSAInput::do_capture()
 216 {
 217         parent_pool->set_card_state(internal_dev_index, ALSAPool::Device::State::STARTING);
 218         RETURN_ON_ERROR("snd_pcm_start()", snd_pcm_start(pcm_handle));
 219         parent_pool->set_card_state(internal_dev_index, ALSAPool::Device::State::RUNNING);
 220
 221         uint64_t num_frames_output = 0;
 222         while (!should_quit) {
 223                 int ret = snd_pcm_wait(pcm_handle, /*timeout=*/100);
 224                 if (ret == 0) continue;  // Timeout.
 225                 if (ret == -EPIPE) {
 226                         fprintf(stderr, "[%s] ALSA overrun\n", device.c_str());
 227                         snd_pcm_prepare(pcm_handle);
 228                         snd_pcm_start(pcm_handle);
 229                         continue;
 230                 }
 231                 RETURN_ON_ERROR("snd_pcm_wait()", ret);
 232
 233                 snd_pcm_sframes_t frames = snd_pcm_readi(pcm_handle, buffer.get(), buffer_frames);
 234                 if (frames == -EPIPE) {
 235                         fprintf(stderr, "[%s] ALSA overrun\n", device.c_str());
 236                         snd_pcm_prepare(pcm_handle);
 237                         snd_pcm_start(pcm_handle);
 238                         continue;
 239                 }
 240                 if (frames == 0) {
 241                         fprintf(stderr, "snd_pcm_readi() returned 0\n");
 242                         break;
 243                 }
 244                 RETURN_ON_ERROR("snd_pcm_readi()", frames);
 245
 246                 const int64_t prev_pts = frames_to_pts(num_frames_output);
 247                 const int64_t pts = frames_to_pts(num_frames_output + frames);
 248                 bool success;
 249                 do {
 250                         if (should_quit) return CaptureEndReason::REQUESTED_QUIT;
 251                         success = audio_callback(buffer.get(), frames, audio_format, pts - prev_pts);
 252                 } while (!success);
 253                 num_frames_output += frames;
 254         }
 255         return CaptureEndReason::REQUESTED_QUIT;
 256 }
 257
 258 int64_t ALSAInput::frames_to_pts(uint64_t n) const
 259 {
 260         return (n * TIMEBASE) / sample_rate;
 261 }
 262
 263 ALSAPool::~ALSAPool()
 264 {
 265         for (Device &device : devices) {
 266                 if (device.input != nullptr) {
 267                         device.input->stop_capture_thread();
 268                 }
 269         }
 270 }
 271
 272 std::vector<ALSAPool::Device> ALSAPool::get_devices()
 273 {
 274         lock_guard<mutex> lock(mu);
 275         for (Device &device : devices) {
 276                 device.held = true;
 277         }
 278         return devices;
 279 }
 280
 281 void ALSAPool::hold_device(unsigned index)
 282 {
 283         lock_guard<mutex> lock(mu);
 284         assert(index < devices.size());
 285         devices[index].held = true;
 286 }
 287
 288 void ALSAPool::release_device(unsigned index)
 289 {
 290         lock_guard<mutex> lock(mu);
 291         if (index < devices.size()) {
 292                 devices[index].held = false;
 293         }
 294 }
 295
 296 void ALSAPool::enumerate_devices()
 297 {
 298         // Enumerate all cards.
 299         for (int card_index = -1; snd_card_next(&card_index) == 0 && card_index >= 0; ) {
 300                 char address[256];
 301                 snprintf(address, sizeof(address), "hw:%d", card_index);
 302
 303                 snd_ctl_t *ctl;
 304                 int err = snd_ctl_open(&ctl, address, 0);
 305                 if (err < 0) {
 306                         printf("%s: %s\n", address, snd_strerror(err));
 307                         continue;
 308                 }
 309                 unique_ptr<snd_ctl_t, decltype(snd_ctl_close)*> ctl_closer(ctl, snd_ctl_close);
 310
 311                 // Enumerate all devices on this card.
 312                 for (int dev_index = -1; snd_ctl_pcm_next_device(ctl, &dev_index) == 0 && dev_index >= 0; ) {
 313                         probe_device_with_retry(card_index, dev_index);
 314                 }
 315         }
 316 }
 317
 318 void ALSAPool::probe_device_with_retry(unsigned card_index, unsigned dev_index)
 319 {
 320         char address[256];
 321         snprintf(address, sizeof(address), "hw:%d,%d", card_index, dev_index);
 322
 323         lock_guard<mutex> lock(add_device_mutex);
 324         if (add_device_tries_left.count(address)) {
 325                 // Some thread is already busy retrying this,
 326                 // so just reset its count.
 327                 add_device_tries_left[address] = num_retries;
 328                 return;
 329         }
 330
 331         // Try (while still holding the lock) to add the device synchronously.
 332         ProbeResult result = probe_device_once(card_index, dev_index);
 333         if (result == ProbeResult::SUCCESS) {
 334                 return;
 335         } else if (result == ProbeResult::FAILURE) {
 336                 return;
 337         }
 338         assert(result == ProbeResult::DEFER);
 339
 340         // Add failed for whatever reason (probably just that the device
 341         // isn't up yet. Set up a count so that nobody else starts a thread,
 342         // then start it ourselves.
 343         fprintf(stderr, "Trying %s again in one second...\n", address);
 344         add_device_tries_left[address] = num_retries;
 345         thread(&ALSAPool::probe_device_retry_thread_func, this, card_index, dev_index).detach();
 346 }
 347
 348 void ALSAPool::probe_device_retry_thread_func(unsigned card_index, unsigned dev_index)
 349 {
 350         char address[256];
 351         snprintf(address, sizeof(address), "hw:%d,%d", card_index, dev_index);
 352
 353         for ( ;; ) {  // Termination condition within the loop.
 354                 sleep(1);
 355
 356                 // See if there are any retries left.
 357                 lock_guard<mutex> lock(add_device_mutex);
 358                 if (!add_device_tries_left.count(address) ||
 359                     add_device_tries_left[address] == 0) {
 360                         add_device_tries_left.erase(address);
 361                         fprintf(stderr, "Giving up probe of %s.\n", address);
 362                         return;
 363                 }
 364
 365                 // Seemingly there were. Give it a try (we still hold the mutex).
 366                 ProbeResult result = probe_device_once(card_index, dev_index);
 367                 if (result == ProbeResult::SUCCESS) {
 368                         add_device_tries_left.erase(address);
 369                         fprintf(stderr, "Probe of %s succeeded.\n", address);
 370                         return;
 371                 } else if (result == ProbeResult::FAILURE || --add_device_tries_left[address] == 0) {
 372                         add_device_tries_left.erase(address);
 373                         fprintf(stderr, "Giving up probe of %s.\n", address);
 374                         return;
 375                 }
 376
 377                 // Failed again.
 378                 assert(result == ProbeResult::DEFER);
 379                 fprintf(stderr, "Trying %s again in one second (%d tries left)...\n",
 380                         address, add_device_tries_left[address]);
 381         }
 382 }
 383
 384 ALSAPool::ProbeResult ALSAPool::probe_device_once(unsigned card_index, unsigned dev_index)
 385 {
 386         char address[256];
 387         snprintf(address, sizeof(address), "hw:%d", card_index);
 388         snd_ctl_t *ctl;
 389         int err = snd_ctl_open(&ctl, address, 0);
 390         if (err < 0) {
 391                 printf("%s: %s\n", address, snd_strerror(err));
 392                 return ALSAPool::ProbeResult::DEFER;
 393         }
 394         unique_ptr<snd_ctl_t, decltype(snd_ctl_close)*> ctl_closer(ctl, snd_ctl_close);
 395
 396         snd_pcm_info_t *pcm_info;
 397         snd_pcm_info_alloca(&pcm_info);
 398         snd_pcm_info_set_device(pcm_info, dev_index);
 399         snd_pcm_info_set_subdevice(pcm_info, 0);
 400         snd_pcm_info_set_stream(pcm_info, SND_PCM_STREAM_CAPTURE);
 401         if (snd_ctl_pcm_info(ctl, pcm_info) < 0) {
 402                 // Not available for capture.
 403                 printf("%s: Not available for capture.\n", address);
 404                 return ALSAPool::ProbeResult::DEFER;
 405         }
 406
 407         snprintf(address, sizeof(address), "hw:%d,%d", card_index, dev_index);
 408
 409         unsigned num_channels = 0;
 410
 411         // Find all channel maps for this device, and pick out the one
 412         // with the most channels.
 413         snd_pcm_chmap_query_t **cmaps = snd_pcm_query_chmaps_from_hw(card_index, dev_index, 0, SND_PCM_STREAM_CAPTURE);
 414         if (cmaps != nullptr) {
 415                 for (snd_pcm_chmap_query_t **ptr = cmaps; *ptr; ++ptr) {
 416                         num_channels = max(num_channels, (*ptr)->map.channels);
 417                 }
 418                 snd_pcm_free_chmaps(cmaps);
 419         }
 420         if (num_channels == 0) {
 421                 // Device had no channel maps. We need to open it to query.
 422                 // TODO: Do this asynchronously.
 423                 snd_pcm_t *pcm_handle;
 424                 int err = snd_pcm_open(&pcm_handle, address, SND_PCM_STREAM_CAPTURE, 0);
 425                 if (err < 0) {
 426                         printf("%s: %s\n", address, snd_strerror(err));
 427                         return ALSAPool::ProbeResult::DEFER;
 428                 }
 429                 snd_pcm_hw_params_t *hw_params;
 430                 snd_pcm_hw_params_alloca(&hw_params);
 431                 unsigned sample_rate;
 432                 if (!set_base_params(address, pcm_handle, hw_params, &sample_rate)) {
 433                         snd_pcm_close(pcm_handle);
 434                         return ALSAPool::ProbeResult::DEFER;
 435                 }
 436                 err = snd_pcm_hw_params_get_channels_max(hw_params, &num_channels);
 437                 if (err < 0) {
 438                         fprintf(stderr, "[%s] snd_pcm_hw_params_get_channels_max(): %s\n",
 439                                 address, snd_strerror(err));
 440                         snd_pcm_close(pcm_handle);
 441                         return ALSAPool::ProbeResult::DEFER;
 442                 }
 443                 snd_pcm_close(pcm_handle);
 444         }
 445
 446         if (num_channels == 0) {
 447                 printf("%s: No channel maps with channels\n", address);
 448                 return ALSAPool::ProbeResult::FAILURE;
 449         }
 450
 451         snd_ctl_card_info_t *card_info;
 452         snd_ctl_card_info_alloca(&card_info);
 453         snd_ctl_card_info(ctl, card_info);
 454
 455         string name = snd_ctl_card_info_get_name(card_info);
 456         string info = snd_pcm_info_get_name(pcm_info);
 457
 458         unsigned internal_dev_index;
 459         string display_name;
 460         {
 461                 lock_guard<mutex> lock(mu);
 462                 internal_dev_index = find_free_device_index(name, info, num_channels, address);
 463                 devices[internal_dev_index].address = address;
 464                 devices[internal_dev_index].name = name;
 465                 devices[internal_dev_index].info = info;
 466                 devices[internal_dev_index].num_channels = num_channels;
 467                 // Note: Purposefully does not overwrite held.
 468
 469                 display_name = devices[internal_dev_index].display_name();
 470         }
 471
 472         fprintf(stderr, "%s: Probed successfully.\n", address);
 473
 474         reset_device(internal_dev_index);  // Restarts it if it is held (ie., we just replaced a dead card).
 475
 476         DeviceSpec spec{InputSourceType::ALSA_INPUT, internal_dev_index};
 477         global_audio_mixer->set_display_name(spec, display_name);
 478         global_audio_mixer->trigger_state_changed_callback();
 479
 480         return ALSAPool::ProbeResult::SUCCESS;
 481 }
 482
 483 void ALSAPool::unplug_device(unsigned card_index, unsigned dev_index)
 484 {
 485         char address[256];
 486         snprintf(address, sizeof(address), "hw:%d,%d", card_index, dev_index);
 487         for (unsigned i = 0; i < devices.size(); ++i) {
 488                 if (devices[i].state != Device::State::EMPTY &&
 489                     devices[i].state != Device::State::DEAD &&
 490                     devices[i].address == address) {
 491                         free_card(i);
 492                 }
 493         }
 494 }
 495
 496 void ALSAPool::init()
 497 {
 498         thread(&ALSAPool::inotify_thread_func, this).detach();
 499         enumerate_devices();
 500 }
 501
 502 void ALSAPool::inotify_thread_func()
 503 {
 504         int inotify_fd = inotify_init();
 505         if (inotify_fd == -1) {
 506                 perror("inotify_init()");
 507                 fprintf(stderr, "No hotplug of ALSA devices available.\n");
 508                 return;
 509         }
 510
 511         int watch_fd = inotify_add_watch(inotify_fd, "/dev/snd", IN_MOVE | IN_CREATE | IN_DELETE);
 512         if (watch_fd == -1) {
 513                 perror("inotify_add_watch()");
 514                 fprintf(stderr, "No hotplug of ALSA devices available.\n");
 515                 close(inotify_fd);
 516                 return;
 517         }
 518
 519         int size = sizeof(inotify_event) + NAME_MAX + 1;
 520         unique_ptr<char[]> buf(new char[size]);
 521         for ( ;; ) {
 522                 int ret = read(inotify_fd, buf.get(), size);
 523                 if (ret < int(sizeof(inotify_event))) {
 524                         fprintf(stderr, "inotify read unexpectedly returned %d, giving up hotplug of ALSA devices.\n",
 525                                 int(ret));
 526                         close(watch_fd);
 527                         close(inotify_fd);
 528                         return;
 529                 }
 530
 531                 for (int i = 0; i < ret; ) {
 532                         const inotify_event *event = reinterpret_cast<const inotify_event *>(&buf[i]);
 533                         i += sizeof(inotify_event) + event->len;
 534
 535                         if (event->mask & IN_Q_OVERFLOW) {
 536                                 fprintf(stderr, "WARNING: inotify overflowed, may lose ALSA hotplug events.\n");
 537                                 continue;
 538                         }
 539                         unsigned card, device;
 540                         char type;
 541                         if (sscanf(event->name, "pcmC%uD%u%c", &card, &device, &type) == 3 && type == 'c') {
 542                                 if (event->mask & (IN_MOVED_FROM | IN_DELETE)) {
 543                                         printf("Deleted capture device: Card %u, device %u\n", card, device);
 544                                         unplug_device(card, device);
 545                                 }
 546                                 if (event->mask & (IN_MOVED_TO | IN_CREATE)) {
 547                                         printf("Adding capture device: Card %u, device %u\n", card, device);
 548                                         probe_device_with_retry(card, device);
 549                                 }
 550                         }
 551                 }
 552         }
 553 }
 554
 555 void ALSAPool::reset_device(unsigned index)
 556 {
 557         lock_guard<mutex> lock(mu);
 558         Device *device = &devices[index];
 559         if (inputs[index] != nullptr) {
 560                 inputs[index]->stop_capture_thread();
 561         }
 562         if (!device->held) {
 563                 inputs[index].reset();
 564         } else {
 565                 // TODO: Put on a background thread instead of locking?
 566                 auto callback = bind(&AudioMixer::add_audio, global_audio_mixer, DeviceSpec{InputSourceType::ALSA_INPUT, index}, _1, _2, _3, _4);
 567                 inputs[index].reset(new ALSAInput(device->address.c_str(), OUTPUT_FREQUENCY, device->num_channels, callback, this, index));
 568                 inputs[index]->start_capture_thread();
 569         }
 570         device->input = inputs[index].get();
 571 }
 572
 573 unsigned ALSAPool::get_capture_frequency(unsigned index)
 574 {
 575         lock_guard<mutex> lock(mu);
 576         assert(devices[index].held);
 577         if (devices[index].input)
 578                 return devices[index].input->get_sample_rate();
 579         else
 580                 return OUTPUT_FREQUENCY;
 581 }
 582
 583 ALSAPool::Device::State ALSAPool::get_card_state(unsigned index)
 584 {
 585         lock_guard<mutex> lock(mu);
 586         assert(devices[index].held);
 587         return devices[index].state;
 588 }
 589
 590 void ALSAPool::set_card_state(unsigned index, ALSAPool::Device::State state)
 591 {
 592         {
 593                 lock_guard<mutex> lock(mu);
 594                 devices[index].state = state;
 595         }
 596
 597         DeviceSpec spec{InputSourceType::ALSA_INPUT, index};
 598         bool silence = (state != ALSAPool::Device::State::RUNNING);
 599         while (!global_audio_mixer->silence_card(spec, silence))
 600                 ;
 601         global_audio_mixer->trigger_state_changed_callback();
 602 }
 603
 604 unsigned ALSAPool::find_free_device_index(const string &name, const string &info, unsigned num_channels, const string &address)
 605 {
 606         // First try to find an exact match on a dead card.
 607         for (unsigned i = 0; i < devices.size(); ++i) {
 608                 if (devices[i].state == Device::State::DEAD &&
 609                     devices[i].address == address &&
 610                     devices[i].name == name &&
 611                     devices[i].info == info &&
 612                     devices[i].num_channels == num_channels) {
 613                         devices[i].state = Device::State::READY;
 614                         return i;
 615                 }
 616         }
 617
 618         // Then try to find a match on everything but the address
 619         // (probably that devices were plugged back in a different order).
 620         // If we have two cards that are equal, this might get them mixed up,
 621         // but we don't have anything better.
 622         for (unsigned i = 0; i < devices.size(); ++i) {
 623                 if (devices[i].state == Device::State::DEAD &&
 624                     devices[i].name == name &&
 625                     devices[i].info == info &&
 626                     devices[i].num_channels == num_channels) {
 627                         devices[i].state = Device::State::READY;
 628                         return i;
 629                 }
 630         }
 631
 632         // OK, so we didn't find a match; see if there are any empty slots.
 633         for (unsigned i = 0; i < devices.size(); ++i) {
 634                 if (devices[i].state == Device::State::EMPTY) {
 635                         devices[i].state = Device::State::READY;
 636                         devices[i].held = false;
 637                         return i;
 638                 }
 639         }
 640
 641         // Failing that, we just insert the new device at the end.
 642         Device new_dev;
 643         new_dev.state = Device::State::READY;
 644         new_dev.held = false;
 645         devices.push_back(new_dev);
 646         inputs.emplace_back(nullptr);
 647         return devices.size() - 1;
 648 }
 649
 650 unsigned ALSAPool::create_dead_card(const string &name, const string &info, unsigned num_channels)
 651 {
 652         lock_guard<mutex> lock(mu);
 653
 654         // See if there are any empty slots. If not, insert one at the end.
 655         vector<Device>::iterator free_device =
 656                 find_if(devices.begin(), devices.end(),
 657                         [](const Device &device) { return device.state == Device::State::EMPTY; });
 658         if (free_device == devices.end()) {
 659                 devices.push_back(Device());
 660                 inputs.emplace_back(nullptr);
 661                 free_device = devices.end() - 1;
 662         }
 663
 664         free_device->state = Device::State::DEAD;
 665         free_device->name = name;
 666         free_device->info = info;
 667         free_device->num_channels = num_channels;
 668         free_device->held = true;
 669
 670         return distance(devices.begin(), free_device);
 671 }
 672
 673 void ALSAPool::serialize_device(unsigned index, DeviceSpecProto *serialized)
 674 {
 675         lock_guard<mutex> lock(mu);
 676         assert(index < devices.size());
 677         assert(devices[index].held);
 678         serialized->set_type(DeviceSpecProto::ALSA_INPUT);
 679         serialized->set_index(index);
 680         serialized->set_display_name(devices[index].display_name());
 681         serialized->set_alsa_name(devices[index].name);
 682         serialized->set_alsa_info(devices[index].info);
 683         serialized->set_num_channels(devices[index].num_channels);
 684         serialized->set_address(devices[index].address);
 685 }
 686
 687 void ALSAPool::free_card(unsigned index)
 688 {
 689         DeviceSpec spec{InputSourceType::ALSA_INPUT, index};
 690         while (!global_audio_mixer->silence_card(spec, true))
 691                 ;
 692
 693         {
 694                 lock_guard<mutex> lock(mu);
 695                 if (devices[index].held) {
 696                         devices[index].state = Device::State::DEAD;
 697                 } else {
 698                         devices[index].state = Device::State::EMPTY;
 699                         inputs[index].reset();
 700                 }
 701                 while (!devices.empty() && devices.back().state == Device::State::EMPTY) {
 702                         devices.pop_back();
 703                         inputs.pop_back();
 704                 }
 705         }
 706
 707         global_audio_mixer->trigger_state_changed_callback();
 708 }