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

   1
   2 #include "alsa_input.h"
   3
   4 using namespace std;
   5
   6 ALSAInput::ALSAInput(const char *device, unsigned sample_rate, unsigned num_channels, audio_callback_t audio_callback)
   7         : device(device), sample_rate(sample_rate), num_channels(num_channels), audio_callback(audio_callback)
   8 {
   9         die_on_error(device, snd_pcm_open(&pcm_handle, device, SND_PCM_STREAM_CAPTURE, 0));
  10
  11         // Set format.
  12         snd_pcm_hw_params_t *hw_params;
  13         snd_pcm_hw_params_alloca(&hw_params);
  14         if (!set_base_params(device, pcm_handle, hw_params, &sample_rate)) {
  15                 exit(1);
  16         }
  17
  18         die_on_error("snd_pcm_hw_params_set_channels()", snd_pcm_hw_params_set_channels(pcm_handle, hw_params, num_channels));
  19
  20         // Fragment size of 64 samples (about 1 ms at 48 kHz; a frame at 60
  21         // fps/48 kHz is 800 samples.) We ask for 64 such periods in our buffer
  22         // (~85 ms buffer); more than that, and our jitter is probably so high
  23         // that the resampling queue can't keep up anyway.
  24         // The entire thing with periods and such is a bit mysterious to me;
  25         // seemingly I can get 96 frames at a time with no problems even if
  26         // the period size is 64 frames. And if I set num_periods to e.g. 1,
  27         // I can't have a big buffer.
  28         num_periods = 16;
  29         int dir = 0;
  30         die_on_error("snd_pcm_hw_params_set_periods_near()", snd_pcm_hw_params_set_periods_near(pcm_handle, hw_params, &num_periods, &dir));
  31         period_size = 64;
  32         dir = 0;
  33         die_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));
  34         buffer_frames = 64 * 64;
  35         die_on_error("snd_pcm_hw_params_set_buffer_size_near()", snd_pcm_hw_params_set_buffer_size_near(pcm_handle, hw_params, &buffer_frames));
  36         die_on_error("snd_pcm_hw_params()", snd_pcm_hw_params(pcm_handle, hw_params));
  37         //snd_pcm_hw_params_free(hw_params);
  38
  39         // Figure out which format the card actually chose.
  40         die_on_error("snd_pcm_hw_params_current()", snd_pcm_hw_params_current(pcm_handle, hw_params));
  41         snd_pcm_format_t chosen_format;
  42         die_on_error("snd_pcm_hw_params_get_format()", snd_pcm_hw_params_get_format(hw_params, &chosen_format));
  43
  44         audio_format.num_channels = num_channels;
  45         audio_format.bits_per_sample = 0;
  46         switch (chosen_format) {
  47         case SND_PCM_FORMAT_S16_LE:
  48                 audio_format.bits_per_sample = 16;
  49                 break;
  50         case SND_PCM_FORMAT_S24_LE:
  51                 audio_format.bits_per_sample = 24;
  52                 break;
  53         case SND_PCM_FORMAT_S32_LE:
  54                 audio_format.bits_per_sample = 32;
  55                 break;
  56         default:
  57                 assert(false);
  58         }
  59         //printf("num_periods=%u period_size=%u buffer_frames=%u sample_rate=%u bits_per_sample=%d\n",
  60         //      num_periods, unsigned(period_size), unsigned(buffer_frames), sample_rate, audio_format.bits_per_sample);
  61
  62         buffer.reset(new uint8_t[buffer_frames * num_channels * audio_format.bits_per_sample / 8]);
  63
  64         snd_pcm_sw_params_t *sw_params;
  65         snd_pcm_sw_params_alloca(&sw_params);
  66         die_on_error("snd_pcm_sw_params_current()", snd_pcm_sw_params_current(pcm_handle, sw_params));
  67         die_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));
  68         die_on_error("snd_pcm_sw_params()", snd_pcm_sw_params(pcm_handle, sw_params));
  69
  70         die_on_error("snd_pcm_nonblock()", snd_pcm_nonblock(pcm_handle, 1));
  71         die_on_error("snd_pcm_prepare()", snd_pcm_prepare(pcm_handle));
  72 }
  73
  74 ALSAInput::~ALSAInput()
  75 {
  76         die_on_error("snd_pcm_close()", snd_pcm_close(pcm_handle));
  77 }
  78
  79 void ALSAInput::start_capture_thread()
  80 {
  81         should_quit = false;
  82         capture_thread = thread(&ALSAInput::capture_thread_func, this);
  83 }
  84
  85 void ALSAInput::stop_capture_thread()
  86 {
  87         should_quit = true;
  88         capture_thread.join();
  89 }
  90
  91 void ALSAInput::capture_thread_func()
  92 {
  93         die_on_error("snd_pcm_start()", snd_pcm_start(pcm_handle));
  94         uint64_t num_frames_output = 0;
  95         while (!should_quit) {
  96                 int ret = snd_pcm_wait(pcm_handle, /*timeout=*/100);
  97                 if (ret == 0) continue;  // Timeout.
  98                 if (ret == -EPIPE) {
  99                         fprintf(stderr, "[%s] ALSA overrun\n", device.c_str());
 100                         snd_pcm_prepare(pcm_handle);
 101                         snd_pcm_start(pcm_handle);
 102                         continue;
 103                 }
 104                 die_on_error("snd_pcm_wait()", ret);
 105
 106                 snd_pcm_sframes_t frames = snd_pcm_readi(pcm_handle, buffer.get(), buffer_frames);
 107                 if (frames == -EPIPE) {
 108                         fprintf(stderr, "[%s] ALSA overrun\n", device.c_str());
 109                         snd_pcm_prepare(pcm_handle);
 110                         snd_pcm_start(pcm_handle);
 111                         continue;
 112                 }
 113                 if (frames == 0) {
 114                         fprintf(stderr, "snd_pcm_readi() returned 0\n");
 115                         break;
 116                 }
 117                 die_on_error("snd_pcm_readi()", frames);
 118
 119                 const int64_t prev_pts = frames_to_pts(num_frames_output);
 120                 const int64_t pts = frames_to_pts(num_frames_output + frames);
 121                 bool success;
 122                 do {
 123                         if (should_quit) return;
 124                         success = audio_callback(buffer.get(), frames, audio_format, pts - prev_pts);
 125                 } while (!success);
 126                 num_frames_output += frames;
 127         }
 128 }
 129
 130 int64_t ALSAInput::frames_to_pts(uint64_t n) const
 131 {
 132         return (n * TIMEBASE) / sample_rate;
 133 }
 134
 135 void ALSAInput::die_on_error(const char *func_name, int err)
 136 {
 137         if (err < 0) {
 138                 fprintf(stderr, "[%s] %s: %s\n", device.c_str(), func_name, snd_strerror(err));
 139                 exit(1);
 140         }
 141 }
 142
 143 bool ALSAInput::set_base_params(const char *device_name, snd_pcm_t *pcm_handle, snd_pcm_hw_params_t *hw_params, unsigned *sample_rate)
 144 {
 145         int err;
 146         err = snd_pcm_hw_params_any(pcm_handle, hw_params);
 147         if (err < 0) {
 148                 fprintf(stderr, "[%s] snd_pcm_hw_params_any(): %s\n", device_name, snd_strerror(err));
 149                 return false;
 150         }
 151         err = snd_pcm_hw_params_set_access(pcm_handle, hw_params, SND_PCM_ACCESS_RW_INTERLEAVED);
 152         if (err < 0) {
 153                 fprintf(stderr, "[%s] snd_pcm_hw_params_set_access(): %s\n", device_name, snd_strerror(err));
 154                 return false;
 155         }
 156         snd_pcm_format_mask_t *format_mask;
 157         snd_pcm_format_mask_alloca(&format_mask);
 158         snd_pcm_format_mask_set(format_mask, SND_PCM_FORMAT_S16_LE);
 159         snd_pcm_format_mask_set(format_mask, SND_PCM_FORMAT_S24_LE);
 160         snd_pcm_format_mask_set(format_mask, SND_PCM_FORMAT_S32_LE);
 161         err = snd_pcm_hw_params_set_format_mask(pcm_handle, hw_params, format_mask);
 162         if (err < 0) {
 163                 fprintf(stderr, "[%s] snd_pcm_hw_params_set_format_mask(): %s\n", device_name, snd_strerror(err));
 164                 return false;
 165         }
 166         err = snd_pcm_hw_params_set_rate_near(pcm_handle, hw_params, sample_rate, 0);
 167         if (err < 0) {
 168                 fprintf(stderr, "[%s] snd_pcm_hw_params_set_rate_near(): %s\n", device_name, snd_strerror(err));
 169                 return false;
 170         }
 171         return true;
 172 }
 173
 174 vector<ALSAInput::Device> ALSAInput::enumerate_devices()
 175 {
 176         vector<Device> ret;
 177
 178         // Enumerate all cards.
 179         for (int card_index = -1; snd_card_next(&card_index) == 0 && card_index >= 0; ) {
 180                 char address[256];
 181                 snprintf(address, sizeof(address), "hw:%d", card_index);
 182
 183                 snd_ctl_t *ctl;
 184                 int err = snd_ctl_open(&ctl, address, 0);
 185                 if (err < 0) {
 186                         printf("%s: %s\n", address, snd_strerror(err));
 187                         continue;
 188                 }
 189                 snd_ctl_card_info_t *card_info;
 190                 snd_ctl_card_info_alloca(&card_info);
 191                 snd_ctl_card_info(ctl, card_info);
 192
 193                 string card_name = snd_ctl_card_info_get_name(card_info);
 194
 195                 // Enumerate all devices on this card.
 196                 for (int dev_index = -1; snd_ctl_pcm_next_device(ctl, &dev_index) == 0 && dev_index >= 0; ) {
 197                         snd_pcm_info_t *pcm_info;
 198                         snd_pcm_info_alloca(&pcm_info);
 199                         snd_pcm_info_set_device(pcm_info, dev_index);
 200                         snd_pcm_info_set_subdevice(pcm_info, 0);
 201                         snd_pcm_info_set_stream(pcm_info, SND_PCM_STREAM_CAPTURE);
 202                         if (snd_ctl_pcm_info(ctl, pcm_info) < 0) {
 203                                 // Not available for capture.
 204                                 continue;
 205                         }
 206
 207                         snprintf(address, sizeof(address), "hw:%d,%d", card_index, dev_index);
 208
 209                         unsigned num_channels = 0;
 210
 211                         // Find all channel maps for this device, and pick out the one
 212                         // with the most channels.
 213                         snd_pcm_chmap_query_t **cmaps = snd_pcm_query_chmaps_from_hw(card_index, dev_index, 0, SND_PCM_STREAM_CAPTURE);
 214                         if (cmaps != nullptr) {
 215                                 for (snd_pcm_chmap_query_t **ptr = cmaps; *ptr; ++ptr) {
 216                                         num_channels = max(num_channels, (*ptr)->map.channels);
 217                                 }
 218                                 snd_pcm_free_chmaps(cmaps);
 219                         }
 220                         if (num_channels == 0) {
 221                                 // Device had no channel maps. We need to open it to query.
 222                                 snd_pcm_t *pcm_handle;
 223                                 int err = snd_pcm_open(&pcm_handle, address, SND_PCM_STREAM_CAPTURE, 0);
 224                                 if (err < 0) {
 225                                         // TODO: When we go to hotplug support, we should support some
 226                                         // retry here, as the device could legitimately be busy.
 227                                         printf("%s: %s\n", address, snd_strerror(err));
 228                                         continue;
 229                                 }
 230                                 snd_pcm_hw_params_t *hw_params;
 231                                 snd_pcm_hw_params_alloca(&hw_params);
 232                                 unsigned sample_rate;
 233                                 if (!set_base_params(address, pcm_handle, hw_params, &sample_rate)) {
 234                                         snd_pcm_close(pcm_handle);
 235                                         continue;
 236                                 }
 237                                 err = snd_pcm_hw_params_get_channels_max(hw_params, &num_channels);
 238                                 if (err < 0) {
 239                                         fprintf(stderr, "[%s] snd_pcm_hw_params_get_channels_max(): %s\n",
 240                                                 address, snd_strerror(err));
 241                                         snd_pcm_close(pcm_handle);
 242                                         continue;
 243                                 }
 244                                 snd_pcm_close(pcm_handle);
 245                         }
 246
 247                         if (num_channels == 0) {
 248                                 printf("%s: No channel maps with channels\n", address);
 249                                 continue;
 250                         }
 251
 252                         Device dev;
 253                         dev.address = address;
 254                         dev.name = card_name;
 255                         dev.info = snd_pcm_info_get_name(pcm_info);
 256                         dev.num_channels = num_channels;
 257
 258                         ret.push_back(dev);
 259                 }
 260                 snd_ctl_close(ctl);
 261         }
 262
 263         return ret;
 264 }