]> git.sesse.net Git - nageru/blob - audio_mixer.cpp
Move the lo-cut into each bus.
[nageru] / audio_mixer.cpp
1 #include "audio_mixer.h"
2
3 #include <assert.h>
4 #include <endian.h>
5 #include <bmusb/bmusb.h>
6 #include <stdio.h>
7 #include <endian.h>
8 #include <cmath>
9
10 #include "db.h"
11 #include "flags.h"
12 #include "timebase.h"
13
14 using namespace bmusb;
15 using namespace std;
16 using namespace std::placeholders;
17
18 namespace {
19
20 // TODO: If these prove to be a bottleneck, they can be SSSE3-optimized
21 // (usually including multiple channels at a time).
22
23 void convert_fixed16_to_fp32(float *dst, size_t out_channel, size_t out_num_channels,
24                              const uint8_t *src, size_t in_channel, size_t in_num_channels,
25                              size_t num_samples)
26 {
27         assert(in_channel < in_num_channels);
28         assert(out_channel < out_num_channels);
29         src += in_channel * 2;
30         dst += out_channel;
31
32         for (size_t i = 0; i < num_samples; ++i) {
33                 int16_t s = le16toh(*(int16_t *)src);
34                 *dst = s * (1.0f / 32768.0f);
35
36                 src += 2 * in_num_channels;
37                 dst += out_num_channels;
38         }
39 }
40
41 void convert_fixed24_to_fp32(float *dst, size_t out_channel, size_t out_num_channels,
42                              const uint8_t *src, size_t in_channel, size_t in_num_channels,
43                              size_t num_samples)
44 {
45         assert(in_channel < in_num_channels);
46         assert(out_channel < out_num_channels);
47         src += in_channel * 3;
48         dst += out_channel;
49
50         for (size_t i = 0; i < num_samples; ++i) {
51                 uint32_t s1 = src[0];
52                 uint32_t s2 = src[1];
53                 uint32_t s3 = src[2];
54                 uint32_t s = s1 | (s1 << 8) | (s2 << 16) | (s3 << 24);
55                 *dst = int(s) * (1.0f / 2147483648.0f);
56
57                 src += 3 * in_num_channels;
58                 dst += out_num_channels;
59         }
60 }
61
62 void convert_fixed32_to_fp32(float *dst, size_t out_channel, size_t out_num_channels,
63                              const uint8_t *src, size_t in_channel, size_t in_num_channels,
64                              size_t num_samples)
65 {
66         assert(in_channel < in_num_channels);
67         assert(out_channel < out_num_channels);
68         src += in_channel * 4;
69         dst += out_channel;
70
71         for (size_t i = 0; i < num_samples; ++i) {
72                 int32_t s = le32toh(*(int32_t *)src);
73                 *dst = s * (1.0f / 2147483648.0f);
74
75                 src += 4 * in_num_channels;
76                 dst += out_num_channels;
77         }
78 }
79
80 float find_peak(const float *samples, size_t num_samples)
81 {
82         float m = fabs(samples[0]);
83         for (size_t i = 1; i < num_samples; ++i) {
84                 m = max(m, fabs(samples[i]));
85         }
86         return m;
87 }
88
89 void deinterleave_samples(const vector<float> &in, vector<float> *out_l, vector<float> *out_r)
90 {
91         size_t num_samples = in.size() / 2;
92         out_l->resize(num_samples);
93         out_r->resize(num_samples);
94
95         const float *inptr = in.data();
96         float *lptr = &(*out_l)[0];
97         float *rptr = &(*out_r)[0];
98         for (size_t i = 0; i < num_samples; ++i) {
99                 *lptr++ = *inptr++;
100                 *rptr++ = *inptr++;
101         }
102 }
103
104 }  // namespace
105
106 AudioMixer::AudioMixer(unsigned num_cards)
107         : num_cards(num_cards),
108           level_compressor(OUTPUT_FREQUENCY),
109           limiter(OUTPUT_FREQUENCY),
110           compressor(OUTPUT_FREQUENCY),
111           correlation(OUTPUT_FREQUENCY)
112 {
113         for (unsigned bus_index = 0; bus_index < MAX_BUSES; ++bus_index) {
114                 locut[bus_index].init(FILTER_HPF, 2);
115                 locut_enabled[bus_index] = global_flags.locut_enabled;
116         }
117         set_gain_staging_db(global_flags.initial_gain_staging_db);
118         set_gain_staging_auto(global_flags.gain_staging_auto);
119         set_compressor_enabled(global_flags.compressor_enabled);
120         set_limiter_enabled(global_flags.limiter_enabled);
121         set_final_makeup_gain_auto(global_flags.final_makeup_gain_auto);
122
123         // Generate a very simple, default input mapping.
124         InputMapping::Bus input;
125         input.name = "Main";
126         input.device.type = InputSourceType::CAPTURE_CARD;
127         input.device.index = 0;
128         input.source_channel[0] = 0;
129         input.source_channel[1] = 1;
130
131         InputMapping new_input_mapping;
132         new_input_mapping.buses.push_back(input);
133         set_input_mapping(new_input_mapping);
134
135         // Look for ALSA cards.
136         available_alsa_cards = ALSAInput::enumerate_devices();
137
138         r128.init(2, OUTPUT_FREQUENCY);
139         r128.integr_start();
140
141         // hlen=16 is pretty low quality, but we use quite a bit of CPU otherwise,
142         // and there's a limit to how important the peak meter is.
143         peak_resampler.setup(OUTPUT_FREQUENCY, OUTPUT_FREQUENCY * 4, /*num_channels=*/2, /*hlen=*/16, /*frel=*/1.0);
144 }
145
146 AudioMixer::~AudioMixer()
147 {
148         for (unsigned card_index = 0; card_index < available_alsa_cards.size(); ++card_index) {
149                 const AudioDevice &device = alsa_inputs[card_index];
150                 if (device.alsa_device != nullptr) {
151                         device.alsa_device->stop_capture_thread();
152                 }
153         }
154 }
155
156
157 void AudioMixer::reset_resampler(DeviceSpec device_spec)
158 {
159         lock_guard<timed_mutex> lock(audio_mutex);
160         reset_resampler_mutex_held(device_spec);
161 }
162
163 void AudioMixer::reset_resampler_mutex_held(DeviceSpec device_spec)
164 {
165         AudioDevice *device = find_audio_device(device_spec);
166
167         if (device->interesting_channels.empty()) {
168                 device->resampling_queue.reset();
169         } else {
170                 // TODO: ResamplingQueue should probably take the full device spec.
171                 // (It's only used for console output, though.)
172                 device->resampling_queue.reset(new ResamplingQueue(device_spec.index, device->capture_frequency, OUTPUT_FREQUENCY, device->interesting_channels.size()));
173         }
174         device->next_local_pts = 0;
175 }
176
177 void AudioMixer::reset_alsa_mutex_held(DeviceSpec device_spec)
178 {
179         assert(device_spec.type == InputSourceType::ALSA_INPUT);
180         unsigned card_index = device_spec.index;
181         AudioDevice *device = find_audio_device(device_spec);
182
183         if (device->alsa_device != nullptr) {
184                 device->alsa_device->stop_capture_thread();
185         }
186         if (device->interesting_channels.empty()) {
187                 device->alsa_device.reset();
188         } else {
189                 const ALSAInput::Device &alsa_dev = available_alsa_cards[card_index];
190                 device->alsa_device.reset(new ALSAInput(alsa_dev.address.c_str(), OUTPUT_FREQUENCY, alsa_dev.num_channels, bind(&AudioMixer::add_audio, this, device_spec, _1, _2, _3, _4)));
191                 device->capture_frequency = device->alsa_device->get_sample_rate();
192                 device->alsa_device->start_capture_thread();
193         }
194 }
195
196 bool AudioMixer::add_audio(DeviceSpec device_spec, const uint8_t *data, unsigned num_samples, AudioFormat audio_format, int64_t frame_length)
197 {
198         AudioDevice *device = find_audio_device(device_spec);
199
200         unique_lock<timed_mutex> lock(audio_mutex, defer_lock);
201         if (!lock.try_lock_for(chrono::milliseconds(10))) {
202                 return false;
203         }
204         if (device->resampling_queue == nullptr) {
205                 // No buses use this device; throw it away.
206                 return true;
207         }
208
209         unsigned num_channels = device->interesting_channels.size();
210         assert(num_channels > 0);
211
212         // Convert the audio to fp32.
213         vector<float> audio;
214         audio.resize(num_samples * num_channels);
215         unsigned channel_index = 0;
216         for (auto channel_it = device->interesting_channels.cbegin(); channel_it != device->interesting_channels.end(); ++channel_it, ++channel_index) {
217                 switch (audio_format.bits_per_sample) {
218                 case 0:
219                         assert(num_samples == 0);
220                         break;
221                 case 16:
222                         convert_fixed16_to_fp32(&audio[0], channel_index, num_channels, data, *channel_it, audio_format.num_channels, num_samples);
223                         break;
224                 case 24:
225                         convert_fixed24_to_fp32(&audio[0], channel_index, num_channels, data, *channel_it, audio_format.num_channels, num_samples);
226                         break;
227                 case 32:
228                         convert_fixed32_to_fp32(&audio[0], channel_index, num_channels, data, *channel_it, audio_format.num_channels, num_samples);
229                         break;
230                 default:
231                         fprintf(stderr, "Cannot handle audio with %u bits per sample\n", audio_format.bits_per_sample);
232                         assert(false);
233                 }
234         }
235
236         // Now add it.
237         int64_t local_pts = device->next_local_pts;
238         device->resampling_queue->add_input_samples(local_pts / double(TIMEBASE), audio.data(), num_samples);
239         device->next_local_pts = local_pts + frame_length;
240         return true;
241 }
242
243 bool AudioMixer::add_silence(DeviceSpec device_spec, unsigned samples_per_frame, unsigned num_frames, int64_t frame_length)
244 {
245         AudioDevice *device = find_audio_device(device_spec);
246
247         unique_lock<timed_mutex> lock(audio_mutex, defer_lock);
248         if (!lock.try_lock_for(chrono::milliseconds(10))) {
249                 return false;
250         }
251         if (device->resampling_queue == nullptr) {
252                 // No buses use this device; throw it away.
253                 return true;
254         }
255
256         unsigned num_channels = device->interesting_channels.size();
257         assert(num_channels > 0);
258
259         vector<float> silence(samples_per_frame * num_channels, 0.0f);
260         for (unsigned i = 0; i < num_frames; ++i) {
261                 device->resampling_queue->add_input_samples(device->next_local_pts / double(TIMEBASE), silence.data(), samples_per_frame);
262                 // Note that if the format changed in the meantime, we have
263                 // no way of detecting that; we just have to assume the frame length
264                 // is always the same.
265                 device->next_local_pts += frame_length;
266         }
267         return true;
268 }
269
270 AudioMixer::AudioDevice *AudioMixer::find_audio_device(DeviceSpec device)
271 {
272         switch (device.type) {
273         case InputSourceType::CAPTURE_CARD:
274                 return &video_cards[device.index];
275         case InputSourceType::ALSA_INPUT:
276                 return &alsa_inputs[device.index];
277         case InputSourceType::SILENCE:
278         default:
279                 assert(false);
280         }
281         return nullptr;
282 }
283
284 // Get a pointer to the given channel from the given device.
285 // The channel must be picked out earlier and resampled.
286 void AudioMixer::find_sample_src_from_device(const map<DeviceSpec, vector<float>> &samples_card, DeviceSpec device_spec, int source_channel, const float **srcptr, unsigned *stride)
287 {
288         static float zero = 0.0f;
289         if (source_channel == -1 || device_spec.type == InputSourceType::SILENCE) {
290                 *srcptr = &zero;
291                 *stride = 0;
292                 return;
293         }
294         AudioDevice *device = find_audio_device(device_spec);
295         assert(device->interesting_channels.count(source_channel) != 0);
296         unsigned channel_index = 0;
297         for (int channel : device->interesting_channels) {
298                 if (channel == source_channel) break;
299                 ++channel_index;
300         }
301         assert(channel_index < device->interesting_channels.size());
302         const auto it = samples_card.find(device_spec);
303         assert(it != samples_card.end());
304         *srcptr = &(it->second)[channel_index];
305         *stride = device->interesting_channels.size();
306 }
307
308 // TODO: Can be SSSE3-optimized if need be.
309 void AudioMixer::fill_audio_bus(const map<DeviceSpec, vector<float>> &samples_card, const InputMapping::Bus &bus, unsigned num_samples, float *output)
310 {
311         if (bus.device.type == InputSourceType::SILENCE) {
312                 memset(output, 0, num_samples * sizeof(*output));
313         } else {
314                 assert(bus.device.type == InputSourceType::CAPTURE_CARD ||
315                        bus.device.type == InputSourceType::ALSA_INPUT);
316                 const float *lsrc, *rsrc;
317                 unsigned lstride, rstride;
318                 float *dptr = output;
319                 find_sample_src_from_device(samples_card, bus.device, bus.source_channel[0], &lsrc, &lstride);
320                 find_sample_src_from_device(samples_card, bus.device, bus.source_channel[1], &rsrc, &rstride);
321                 for (unsigned i = 0; i < num_samples; ++i) {
322                         *dptr++ = *lsrc;
323                         *dptr++ = *rsrc;
324                         lsrc += lstride;
325                         rsrc += rstride;
326                 }
327         }
328 }
329
330 vector<float> AudioMixer::get_output(double pts, unsigned num_samples, ResamplingQueue::RateAdjustmentPolicy rate_adjustment_policy)
331 {
332         map<DeviceSpec, vector<float>> samples_card;
333         vector<float> samples_bus;
334
335         lock_guard<timed_mutex> lock(audio_mutex);
336
337         // Pick out all the interesting channels from all the cards.
338         // TODO: If the card has been hotswapped, the number of channels
339         // might have changed; if so, we need to do some sort of remapping
340         // to silence.
341         for (const auto &spec_and_info : get_devices_mutex_held()) {
342                 const DeviceSpec &device_spec = spec_and_info.first;
343                 AudioDevice *device = find_audio_device(device_spec);
344                 if (!device->interesting_channels.empty()) {
345                         samples_card[device_spec].resize(num_samples * device->interesting_channels.size());
346                         device->resampling_queue->get_output_samples(
347                                 pts,
348                                 &samples_card[device_spec][0],
349                                 num_samples,
350                                 rate_adjustment_policy);
351                 }
352         }
353
354         // TODO: Move lo-cut etc. into each bus.
355         vector<float> samples_out, left, right;
356         samples_out.resize(num_samples * 2);
357         samples_bus.resize(num_samples * 2);
358         for (unsigned bus_index = 0; bus_index < input_mapping.buses.size(); ++bus_index) {
359                 fill_audio_bus(samples_card, input_mapping.buses[bus_index], num_samples, &samples_bus[0]);
360
361                 // Cut away everything under 120 Hz (or whatever the cutoff is);
362                 // we don't need it for voice, and it will reduce headroom
363                 // and confuse the compressor. (In particular, any hums at 50 or 60 Hz
364                 // should be dampened.)
365                 if (locut_enabled[bus_index]) {
366                         locut[bus_index].render(samples_bus.data(), samples_bus.size() / 2, locut_cutoff_hz * 2.0 * M_PI / OUTPUT_FREQUENCY, 0.5f);
367                 }
368
369                 // TODO: We should measure post-fader.
370                 deinterleave_samples(samples_bus, &left, &right);
371                 measure_bus_levels(bus_index, left, right);
372
373                 float volume = from_db(fader_volume_db[bus_index]);
374                 if (bus_index == 0) {
375                         for (unsigned i = 0; i < num_samples * 2; ++i) {
376                                 samples_out[i] = samples_bus[i] * volume;
377                         }
378                 } else {
379                         for (unsigned i = 0; i < num_samples * 2; ++i) {
380                                 samples_out[i] += samples_bus[i] * volume;
381                         }
382                 }
383         }
384
385         {
386                 lock_guard<mutex> lock(compressor_mutex);
387
388                 // Apply a level compressor to get the general level right.
389                 // Basically, if it's over about -40 dBFS, we squeeze it down to that level
390                 // (or more precisely, near it, since we don't use infinite ratio),
391                 // then apply a makeup gain to get it to -14 dBFS. -14 dBFS is, of course,
392                 // entirely arbitrary, but from practical tests with speech, it seems to
393                 // put ut around -23 LUFS, so it's a reasonable starting point for later use.
394                 {
395                         if (level_compressor_enabled) {
396                                 float threshold = 0.01f;   // -40 dBFS.
397                                 float ratio = 20.0f;
398                                 float attack_time = 0.5f;
399                                 float release_time = 20.0f;
400                                 float makeup_gain = from_db(ref_level_dbfs - (-40.0f));  // +26 dB.
401                                 level_compressor.process(samples_out.data(), samples_out.size() / 2, threshold, ratio, attack_time, release_time, makeup_gain);
402                                 gain_staging_db = to_db(level_compressor.get_attenuation() * makeup_gain);
403                         } else {
404                                 // Just apply the gain we already had.
405                                 float g = from_db(gain_staging_db);
406                                 for (size_t i = 0; i < samples_out.size(); ++i) {
407                                         samples_out[i] *= g;
408                                 }
409                         }
410                 }
411
412         #if 0
413                 printf("level=%f (%+5.2f dBFS) attenuation=%f (%+5.2f dB) end_result=%+5.2f dB\n",
414                         level_compressor.get_level(), to_db(level_compressor.get_level()),
415                         level_compressor.get_attenuation(), to_db(level_compressor.get_attenuation()),
416                         to_db(level_compressor.get_level() * level_compressor.get_attenuation() * makeup_gain));
417         #endif
418
419         //      float limiter_att, compressor_att;
420
421                 // The real compressor.
422                 if (compressor_enabled) {
423                         float threshold = from_db(compressor_threshold_dbfs);
424                         float ratio = 20.0f;
425                         float attack_time = 0.005f;
426                         float release_time = 0.040f;
427                         float makeup_gain = 2.0f;  // +6 dB.
428                         compressor.process(samples_out.data(), samples_out.size() / 2, threshold, ratio, attack_time, release_time, makeup_gain);
429         //              compressor_att = compressor.get_attenuation();
430                 }
431
432                 // Finally a limiter at -4 dB (so, -10 dBFS) to take out the worst peaks only.
433                 // Note that since ratio is not infinite, we could go slightly higher than this.
434                 if (limiter_enabled) {
435                         float threshold = from_db(limiter_threshold_dbfs);
436                         float ratio = 30.0f;
437                         float attack_time = 0.0f;  // Instant.
438                         float release_time = 0.020f;
439                         float makeup_gain = 1.0f;  // 0 dB.
440                         limiter.process(samples_out.data(), samples_out.size() / 2, threshold, ratio, attack_time, release_time, makeup_gain);
441         //              limiter_att = limiter.get_attenuation();
442                 }
443
444         //      printf("limiter=%+5.1f  compressor=%+5.1f\n", to_db(limiter_att), to_db(compressor_att));
445         }
446
447         // At this point, we are most likely close to +0 LU, but all of our
448         // measurements have been on raw sample values, not R128 values.
449         // So we have a final makeup gain to get us to +0 LU; the gain
450         // adjustments required should be relatively small, and also, the
451         // offset shouldn't change much (only if the type of audio changes
452         // significantly). Thus, we shoot for updating this value basically
453         // “whenever we process buffers”, since the R128 calculation isn't exactly
454         // something we get out per-sample.
455         //
456         // Note that there's a feedback loop here, so we choose a very slow filter
457         // (half-time of 30 seconds).
458         double target_loudness_factor, alpha;
459         double loudness_lu = r128.loudness_M() - ref_level_lufs;
460         double current_makeup_lu = to_db(final_makeup_gain);
461         target_loudness_factor = final_makeup_gain * from_db(-loudness_lu);
462
463         // If we're outside +/- 5 LU uncorrected, we don't count it as
464         // a normal signal (probably silence) and don't change the
465         // correction factor; just apply what we already have.
466         if (fabs(loudness_lu - current_makeup_lu) >= 5.0 || !final_makeup_gain_auto) {
467                 alpha = 0.0;
468         } else {
469                 // Formula adapted from
470                 // https://en.wikipedia.org/wiki/Low-pass_filter#Simple_infinite_impulse_response_filter.
471                 const double half_time_s = 30.0;
472                 const double fc_mul_2pi_delta_t = 1.0 / (half_time_s * OUTPUT_FREQUENCY);
473                 alpha = fc_mul_2pi_delta_t / (fc_mul_2pi_delta_t + 1.0);
474         }
475
476         {
477                 lock_guard<mutex> lock(compressor_mutex);
478                 double m = final_makeup_gain;
479                 for (size_t i = 0; i < samples_out.size(); i += 2) {
480                         samples_out[i + 0] *= m;
481                         samples_out[i + 1] *= m;
482                         m += (target_loudness_factor - m) * alpha;
483                 }
484                 final_makeup_gain = m;
485         }
486
487         update_meters(samples_out);
488
489         return samples_out;
490 }
491
492 void AudioMixer::measure_bus_levels(unsigned bus_index, const vector<float> &left, const vector<float> &right)
493 {
494         const float *ptrs[] = { left.data(), right.data() };
495         {
496                 lock_guard<mutex> lock(audio_measure_mutex);
497                 bus_r128[bus_index]->process(left.size(), const_cast<float **>(ptrs));
498         }
499 }
500
501 void AudioMixer::update_meters(const vector<float> &samples)
502 {
503         // Upsample 4x to find interpolated peak.
504         peak_resampler.inp_data = const_cast<float *>(samples.data());
505         peak_resampler.inp_count = samples.size() / 2;
506
507         vector<float> interpolated_samples;
508         interpolated_samples.resize(samples.size());
509         {
510                 lock_guard<mutex> lock(audio_measure_mutex);
511
512                 while (peak_resampler.inp_count > 0) {  // About four iterations.
513                         peak_resampler.out_data = &interpolated_samples[0];
514                         peak_resampler.out_count = interpolated_samples.size() / 2;
515                         peak_resampler.process();
516                         size_t out_stereo_samples = interpolated_samples.size() / 2 - peak_resampler.out_count;
517                         peak = max<float>(peak, find_peak(interpolated_samples.data(), out_stereo_samples * 2));
518                         peak_resampler.out_data = nullptr;
519                 }
520         }
521
522         // Find R128 levels and L/R correlation.
523         vector<float> left, right;
524         deinterleave_samples(samples, &left, &right);
525         float *ptrs[] = { left.data(), right.data() };
526         {
527                 lock_guard<mutex> lock(audio_measure_mutex);
528                 r128.process(left.size(), ptrs);
529                 correlation.process_samples(samples);
530         }
531
532         send_audio_level_callback();
533 }
534
535 void AudioMixer::reset_meters()
536 {
537         lock_guard<mutex> lock(audio_measure_mutex);
538         peak_resampler.reset();
539         peak = 0.0f;
540         r128.reset();
541         r128.integr_start();
542         correlation.reset();
543 }
544
545 void AudioMixer::send_audio_level_callback()
546 {
547         if (audio_level_callback == nullptr) {
548                 return;
549         }
550
551         lock_guard<mutex> lock(audio_measure_mutex);
552         double loudness_s = r128.loudness_S();
553         double loudness_i = r128.integrated();
554         double loudness_range_low = r128.range_min();
555         double loudness_range_high = r128.range_max();
556
557         vector<float> bus_loudness;
558         bus_loudness.resize(input_mapping.buses.size());
559         for (unsigned bus_index = 0; bus_index < bus_r128.size(); ++bus_index) {
560                 bus_loudness[bus_index] = bus_r128[bus_index]->loudness_S();
561         }
562
563         audio_level_callback(loudness_s, to_db(peak), bus_loudness,
564                 loudness_i, loudness_range_low, loudness_range_high,
565                 gain_staging_db,
566                 to_db(final_makeup_gain),
567                 correlation.get_correlation());
568 }
569
570 map<DeviceSpec, DeviceInfo> AudioMixer::get_devices() const
571 {
572         lock_guard<timed_mutex> lock(audio_mutex);
573         return get_devices_mutex_held();
574 }
575
576 map<DeviceSpec, DeviceInfo> AudioMixer::get_devices_mutex_held() const
577 {
578         map<DeviceSpec, DeviceInfo> devices;
579         for (unsigned card_index = 0; card_index < num_cards; ++card_index) {
580                 const DeviceSpec spec{ InputSourceType::CAPTURE_CARD, card_index };
581                 const AudioDevice *device = &video_cards[card_index];
582                 DeviceInfo info;
583                 info.name = device->name;
584                 info.num_channels = 8;  // FIXME: This is wrong for fake cards.
585                 devices.insert(make_pair(spec, info));
586         }
587         for (unsigned card_index = 0; card_index < available_alsa_cards.size(); ++card_index) {
588                 const DeviceSpec spec{ InputSourceType::ALSA_INPUT, card_index };
589                 const ALSAInput::Device &device = available_alsa_cards[card_index];
590                 DeviceInfo info;
591                 info.name = device.name + " (" + device.info + ")";
592                 info.num_channels = device.num_channels;
593                 devices.insert(make_pair(spec, info));
594         }
595         return devices;
596 }
597
598 void AudioMixer::set_name(DeviceSpec device_spec, const string &name)
599 {
600         AudioDevice *device = find_audio_device(device_spec);
601
602         lock_guard<timed_mutex> lock(audio_mutex);
603         device->name = name;
604 }
605
606 void AudioMixer::set_input_mapping(const InputMapping &new_input_mapping)
607 {
608         lock_guard<timed_mutex> lock(audio_mutex);
609
610         map<DeviceSpec, set<unsigned>> interesting_channels;
611         for (const InputMapping::Bus &bus : new_input_mapping.buses) {
612                 if (bus.device.type == InputSourceType::CAPTURE_CARD ||
613                     bus.device.type == InputSourceType::ALSA_INPUT) {
614                         for (unsigned channel = 0; channel < 2; ++channel) {
615                                 if (bus.source_channel[channel] != -1) {
616                                         interesting_channels[bus.device].insert(bus.source_channel[channel]);
617                                 }
618                         }
619                 }
620         }
621
622         // Reset resamplers for all cards that don't have the exact same state as before.
623         for (const auto &spec_and_info : get_devices_mutex_held()) {
624                 const DeviceSpec &device_spec = spec_and_info.first;
625                 AudioDevice *device = find_audio_device(device_spec);
626                 if (device->interesting_channels != interesting_channels[device_spec]) {
627                         device->interesting_channels = interesting_channels[device_spec];
628                         if (device_spec.type == InputSourceType::ALSA_INPUT) {
629                                 reset_alsa_mutex_held(device_spec);
630                         }
631                         reset_resampler_mutex_held(device_spec);
632                 }
633         }
634
635         {
636                 lock_guard<mutex> lock(audio_measure_mutex);
637                 bus_r128.resize(new_input_mapping.buses.size());
638                 for (unsigned bus_index = 0; bus_index < bus_r128.size(); ++bus_index) {
639                         if (bus_r128[bus_index] == nullptr) {
640                                 bus_r128[bus_index].reset(new Ebu_r128_proc);
641                         }
642                         bus_r128[bus_index]->init(2, OUTPUT_FREQUENCY);
643                 }
644         }
645
646         input_mapping = new_input_mapping;
647 }
648
649 InputMapping AudioMixer::get_input_mapping() const
650 {
651         lock_guard<timed_mutex> lock(audio_mutex);
652         return input_mapping;
653 }