]> git.sesse.net Git - nageru/blobdiff - midi_mapper.cpp
Support audio-only FFmpeg inputs. Somewhat wonky, though.
[nageru] / midi_mapper.cpp
index fca926f13661f084dca1cb8542f59527139d7a98..3b22192b3b8b0670356ebdb9230a8133777b0983 100644 (file)
@@ -1,16 +1,26 @@
 #include "midi_mapper.h"
-#include "midi_mapping.pb.h"
 
 #include <alsa/asoundlib.h>
-#include <google/protobuf/text_format.h>
-#include <google/protobuf/io/zero_copy_stream.h>
-#include <google/protobuf/io/zero_copy_stream_impl.h>
+#include <assert.h>
+#include <errno.h>
 #include <fcntl.h>
+#include <google/protobuf/descriptor.h>
+#include <google/protobuf/io/zero_copy_stream_impl.h>
+#include <google/protobuf/message.h>
+#include <google/protobuf/text_format.h>
+#include <pthread.h>
+#include <poll.h>
+#include <stdint.h>
+#include <stdio.h>
 #include <sys/eventfd.h>
-
+#include <unistd.h>
+#include <algorithm>
 #include <functional>
 #include <thread>
 
+#include "audio_mixer.h"
+#include "midi_mapping.pb.h"
+
 using namespace google::protobuf;
 using namespace std;
 using namespace std::placeholders;
@@ -42,7 +52,10 @@ MIDIMapper::~MIDIMapper()
 {
        should_quit = true;
        const uint64_t one = 1;
-       write(should_quit_fd, &one, sizeof(one));
+       if (write(should_quit_fd, &one, sizeof(one)) != sizeof(one)) {
+               perror("write(should_quit_fd)");
+               exit(1);
+       }
        midi_thread.join();
        close(should_quit_fd);
 }
@@ -64,8 +77,29 @@ bool load_midi_mapping_from_file(const string &filename, MIDIMappingProto *new_m
        return true;
 }
 
+bool save_midi_mapping_to_file(const MIDIMappingProto &mapping_proto, const string &filename)
+{
+       // Save to disk. We use the text format because it's friendlier
+       // for a user to look at and edit.
+       int fd = open(filename.c_str(), O_WRONLY | O_TRUNC | O_CREAT, 0666);
+       if (fd == -1) {
+               perror(filename.c_str());
+               return false;
+       }
+       io::FileOutputStream output(fd);  // Takes ownership of fd.
+       if (!TextFormat::Print(mapping_proto, &output)) {
+               // TODO: Don't overwrite the old file (if any) on error.
+               output.Close();
+               return false;
+       }
+
+       output.Close();
+       return true;
+}
+
 void MIDIMapper::set_midi_mapping(const MIDIMappingProto &new_mapping)
 {
+       lock_guard<mutex> lock(mu);
        if (mapping_proto) {
                mapping_proto->CopyFrom(new_mapping);
        } else {
@@ -74,6 +108,9 @@ void MIDIMapper::set_midi_mapping(const MIDIMappingProto &new_mapping)
 
        num_controller_banks = min(max(mapping_proto->num_controller_banks(), 1), 5);
         current_controller_bank = 0;
+
+       receiver->clear_all_highlights();
+       update_highlights();
 }
 
 void MIDIMapper::start_thread()
@@ -81,6 +118,19 @@ void MIDIMapper::start_thread()
        midi_thread = thread(&MIDIMapper::thread_func, this);
 }
 
+const MIDIMappingProto &MIDIMapper::get_current_mapping() const
+{
+       lock_guard<mutex> lock(mu);
+       return *mapping_proto;
+}
+
+ControllerReceiver *MIDIMapper::set_receiver(ControllerReceiver *new_receiver)
+{
+       lock_guard<mutex> lock(mu);
+       swap(receiver, new_receiver);
+       return new_receiver;  // Now old receiver.
+}
+
 #define RETURN_ON_ERROR(msg, expr) do {                            \
        int err = (expr);                                          \
        if (err < 0) {                                             \
@@ -89,10 +139,18 @@ void MIDIMapper::start_thread()
        }                                                          \
 } while (false)
 
+#define WARN_ON_ERROR(msg, expr) do {                              \
+       int err = (expr);                                          \
+       if (err < 0) {                                             \
+               fprintf(stderr, msg ": %s\n", snd_strerror(err));  \
+       }                                                          \
+} while (false)
+
 
 void MIDIMapper::thread_func()
 {
-       // TODO: Listen on any port, instead of hardcoding 24:0.
+       pthread_setname_np(pthread_self(), "MIDIMapper");
+
        snd_seq_t *seq;
        int err;
 
@@ -101,14 +159,48 @@ void MIDIMapper::thread_func()
        RETURN_ON_ERROR("snd_seq_client_name", snd_seq_set_client_name(seq, "nageru"));
        RETURN_ON_ERROR("snd_seq_create_simple_port",
                snd_seq_create_simple_port(seq, "nageru",
-                       SND_SEQ_PORT_CAP_WRITE |
-                       SND_SEQ_PORT_CAP_SUBS_WRITE,
+                       SND_SEQ_PORT_CAP_READ |
+                               SND_SEQ_PORT_CAP_SUBS_READ |
+                               SND_SEQ_PORT_CAP_WRITE |
+                               SND_SEQ_PORT_CAP_SUBS_WRITE,
                        SND_SEQ_PORT_TYPE_MIDI_GENERIC |
-                       SND_SEQ_PORT_TYPE_APPLICATION));
+                               SND_SEQ_PORT_TYPE_APPLICATION));
 
-       snd_seq_addr_t addr;
-       RETURN_ON_ERROR("snd_seq_parse_address", snd_seq_parse_address(seq, &addr, "24:0"));
-       RETURN_ON_ERROR("snd_seq_connect_from", snd_seq_connect_from(seq, 0, addr.client, addr.port));
+       int queue_id = snd_seq_alloc_queue(seq);
+       RETURN_ON_ERROR("snd_seq_create_queue", queue_id);
+       RETURN_ON_ERROR("snd_seq_start_queue", snd_seq_start_queue(seq, queue_id, nullptr));
+
+       // The sequencer object is now ready to be used from other threads.
+       {
+               lock_guard<mutex> lock(mu);
+               alsa_seq = seq;
+               alsa_queue_id = queue_id;
+       }
+
+       // Listen to the announce port (0:1), which will tell us about new ports.
+       RETURN_ON_ERROR("snd_seq_connect_from", snd_seq_connect_from(seq, 0, /*client=*/0, /*port=*/1));
+
+       // Now go through all ports and subscribe to them.
+       snd_seq_client_info_t *cinfo;
+       snd_seq_client_info_alloca(&cinfo);
+
+       snd_seq_client_info_set_client(cinfo, -1);
+       while (snd_seq_query_next_client(seq, cinfo) >= 0) {
+               int client = snd_seq_client_info_get_client(cinfo);
+
+               snd_seq_port_info_t *pinfo;
+               snd_seq_port_info_alloca(&pinfo);
+
+               snd_seq_port_info_set_client(pinfo, client);
+               snd_seq_port_info_set_port(pinfo, -1);
+               while (snd_seq_query_next_port(seq, pinfo) >= 0) {
+                       constexpr int mask = SND_SEQ_PORT_CAP_READ | SND_SEQ_PORT_CAP_SUBS_READ;
+                       if ((snd_seq_port_info_get_capability(pinfo) & mask) == mask) {
+                               lock_guard<mutex> lock(mu);
+                               subscribe_to_port_lock_held(seq, *snd_seq_port_info_get_addr(pinfo));
+                       }
+               }
+       }
 
        int num_alsa_fds = snd_seq_poll_descriptors_count(seq, POLLIN);
        unique_ptr<pollfd[]> fds(new pollfd[num_alsa_fds + 1]);
@@ -140,6 +232,10 @@ void MIDIMapper::thread_func()
                        if (err < 0) {
                                if (err == -EINTR) continue;
                                if (err == -EAGAIN) break;
+                               if (err == -ENOSPC) {
+                                       fprintf(stderr, "snd_seq_event_input: Some events were lost.\n");
+                                       continue;
+                               }
                                fprintf(stderr, "snd_seq_event_input: %s\n", snd_strerror(err));
                                return;
                        }
@@ -152,13 +248,19 @@ void MIDIMapper::thread_func()
 
 void MIDIMapper::handle_event(snd_seq_t *seq, snd_seq_event_t *event)
 {
+       if (event->source.client == snd_seq_client_id(seq)) {
+               // Ignore events we sent out ourselves.
+               return;
+       }
+
+       lock_guard<mutex> lock(mu);
        switch (event->type) {
        case SND_SEQ_EVENT_CONTROLLER: {
-               printf("Controller %d changed to %d\n", event->data.control.param, event->data.control.value);
-
                const int controller = event->data.control.param;
                const float value = map_controller_to_float(event->data.control.value);
 
+               receiver->controller_changed(controller);
+
                // Global controllers.
                match_controller(controller, MIDIMappingBusProto::kLocutFieldNumber, MIDIMappingProto::kLocutBankFieldNumber,
                        value, bind(&ControllerReceiver::set_locut, receiver, _2));
@@ -168,6 +270,8 @@ void MIDIMapper::handle_event(snd_seq_t *seq, snd_seq_event_t *event)
                        value, bind(&ControllerReceiver::set_makeup_gain, receiver, _2));
 
                // Bus controllers.
+               match_controller(controller, MIDIMappingBusProto::kStereoWidthFieldNumber, MIDIMappingProto::kStereoWidthBankFieldNumber,
+                       value, bind(&ControllerReceiver::set_stereo_width, receiver, _1, _2));
                match_controller(controller, MIDIMappingBusProto::kTrebleFieldNumber, MIDIMappingProto::kTrebleBankFieldNumber,
                        value, bind(&ControllerReceiver::set_treble, receiver, _1, _2));
                match_controller(controller, MIDIMappingBusProto::kMidFieldNumber, MIDIMappingProto::kMidBankFieldNumber,
@@ -185,42 +289,55 @@ void MIDIMapper::handle_event(snd_seq_t *seq, snd_seq_event_t *event)
        case SND_SEQ_EVENT_NOTEON: {
                const int note = event->data.note.note;
 
-               printf("Note: %d\n", note);
+               receiver->note_on(note);
 
-               // Bank change commands. TODO: Highlight the bank change in the UI.
                for (size_t bus_idx = 0; bus_idx < size_t(mapping_proto->bus_mapping_size()); ++bus_idx) {
                        const MIDIMappingBusProto &bus_mapping = mapping_proto->bus_mapping(bus_idx);
                        if (bus_mapping.has_prev_bank() &&
                            bus_mapping.prev_bank().note_number() == note) {
                                current_controller_bank = (current_controller_bank + num_controller_banks - 1) % num_controller_banks;
+                               update_highlights();
+                               update_lights_lock_held();
                        }
                        if (bus_mapping.has_next_bank() &&
                            bus_mapping.next_bank().note_number() == note) {
                                current_controller_bank = (current_controller_bank + 1) % num_controller_banks;
+                               update_highlights();
+                               update_lights_lock_held();
                        }
                        if (bus_mapping.has_select_bank_1() &&
                            bus_mapping.select_bank_1().note_number() == note) {
                                current_controller_bank = 0;
+                               update_highlights();
+                               update_lights_lock_held();
                        }
                        if (bus_mapping.has_select_bank_2() &&
                            bus_mapping.select_bank_2().note_number() == note &&
                            num_controller_banks >= 2) {
                                current_controller_bank = 1;
+                               update_highlights();
+                               update_lights_lock_held();
                        }
                        if (bus_mapping.has_select_bank_3() &&
                            bus_mapping.select_bank_3().note_number() == note &&
                            num_controller_banks >= 3) {
                                current_controller_bank = 2;
+                               update_highlights();
+                               update_lights_lock_held();
                        }
                        if (bus_mapping.has_select_bank_4() &&
                            bus_mapping.select_bank_4().note_number() == note &&
                            num_controller_banks >= 4) {
                                current_controller_bank = 3;
+                               update_highlights();
+                               update_lights_lock_held();
                        }
                        if (bus_mapping.has_select_bank_5() &&
                            bus_mapping.select_bank_5().note_number() == note &&
                            num_controller_banks >= 5) {
                                current_controller_bank = 4;
+                               update_highlights();
+                               update_lights_lock_held();
                        }
                }
 
@@ -232,15 +349,83 @@ void MIDIMapper::handle_event(snd_seq_t *seq, snd_seq_event_t *event)
                        bind(&ControllerReceiver::toggle_compressor, receiver, _1));
                match_button(note, MIDIMappingBusProto::kClearPeakFieldNumber, MIDIMappingProto::kClearPeakBankFieldNumber,
                        bind(&ControllerReceiver::clear_peak, receiver, _1));
+               match_button(note, MIDIMappingBusProto::kToggleMuteFieldNumber, MIDIMappingProto::kClearPeakBankFieldNumber,
+                       bind(&ControllerReceiver::toggle_mute, receiver, _1));
+               match_button(note, MIDIMappingBusProto::kToggleLimiterFieldNumber, MIDIMappingProto::kToggleLimiterBankFieldNumber,
+                       bind(&ControllerReceiver::toggle_limiter, receiver));
+               match_button(note, MIDIMappingBusProto::kToggleAutoMakeupGainFieldNumber, MIDIMappingProto::kToggleAutoMakeupGainBankFieldNumber,
+                       bind(&ControllerReceiver::toggle_auto_makeup_gain, receiver));
+               break;
        }
+       case SND_SEQ_EVENT_PORT_START:
+               subscribe_to_port_lock_held(seq, event->data.addr);
+               break;
+       case SND_SEQ_EVENT_PORT_EXIT:
+               printf("MIDI port %d:%d went away.\n", event->data.addr.client, event->data.addr.port);
+               break;
+       case SND_SEQ_EVENT_PORT_SUBSCRIBED:
+               if (event->data.connect.sender.client != 0 &&  // Ignore system senders.
+                   event->data.connect.sender.client != snd_seq_client_id(seq) &&
+                   event->data.connect.dest.client == snd_seq_client_id(seq)) {
+                       ++num_subscribed_ports;
+                       update_highlights();
+               }
+               break;
+       case SND_SEQ_EVENT_PORT_UNSUBSCRIBED:
+               if (event->data.connect.sender.client != 0 &&  // Ignore system senders.
+                   event->data.connect.sender.client != snd_seq_client_id(seq) &&
+                   event->data.connect.dest.client == snd_seq_client_id(seq)) {
+                       --num_subscribed_ports;
+                       update_highlights();
+               }
+               break;
        case SND_SEQ_EVENT_NOTEOFF:
-               // Ignore.
+       case SND_SEQ_EVENT_CLIENT_START:
+       case SND_SEQ_EVENT_CLIENT_EXIT:
+       case SND_SEQ_EVENT_CLIENT_CHANGE:
+       case SND_SEQ_EVENT_PORT_CHANGE:
                break;
        default:
                printf("Ignoring MIDI event of unknown type %d.\n", event->type);
        }
 }
 
+void MIDIMapper::subscribe_to_port_lock_held(snd_seq_t *seq, const snd_seq_addr_t &addr)
+{
+       // Client 0 (SNDRV_SEQ_CLIENT_SYSTEM) is basically the system; ignore it.
+       // MIDI through (SNDRV_SEQ_CLIENT_DUMMY) echoes back what we give it, so ignore that, too.
+       if (addr.client == 0 || addr.client == 14) {
+               return;
+       }
+
+       // Don't listen to ourselves.
+       if (addr.client == snd_seq_client_id(seq)) {
+               return;
+       }
+
+       int err = snd_seq_connect_from(seq, 0, addr.client, addr.port);
+       if (err < 0) {
+               // Just print out a warning (i.e., don't die); it could
+               // very well just be e.g. another application.
+               printf("Couldn't subscribe to MIDI port %d:%d (%s).\n",
+                       addr.client, addr.port, snd_strerror(err));
+       } else {
+               printf("Subscribed to MIDI port %d:%d.\n", addr.client, addr.port);
+       }
+
+       // For sending data back.
+       err = snd_seq_connect_to(seq, 0, addr.client, addr.port);
+       if (err < 0) {
+               printf("Couldn't subscribe MIDI port %d:%d (%s) to us.\n",
+                       addr.client, addr.port, snd_strerror(err));
+       } else {
+               printf("Subscribed MIDI port %d:%d to us.\n", addr.client, addr.port);
+       }
+
+       current_light_status.clear();  // The current state of the device is unknown.
+       update_lights_lock_held();
+}
+
 void MIDIMapper::match_controller(int controller, int field_number, int bank_field_number, float value, function<void(unsigned, float)> func)
 {
        if (bank_mismatch(bank_field_number)) {
@@ -285,6 +470,18 @@ void MIDIMapper::match_button(int note, int field_number, int bank_field_number,
        }
 }
 
+bool MIDIMapper::has_active_controller(unsigned bus_idx, int field_number, int bank_field_number)
+{
+       if (bank_mismatch(bank_field_number)) {
+               return false;
+       }
+
+       const MIDIMappingBusProto &bus_mapping = mapping_proto->bus_mapping(bus_idx);
+       const FieldDescriptor *descriptor = bus_mapping.GetDescriptor()->FindFieldByNumber(field_number);
+       const Reflection *bus_reflection = bus_mapping.GetReflection();
+       return bus_reflection->HasField(bus_mapping, descriptor);
+}
+
 bool MIDIMapper::bank_mismatch(int bank_field_number)
 {
        const FieldDescriptor *bank_descriptor = mapping_proto->GetDescriptor()->FindFieldByNumber(bank_field_number);
@@ -292,3 +489,188 @@ bool MIDIMapper::bank_mismatch(int bank_field_number)
        return (reflection->HasField(*mapping_proto, bank_descriptor) &&
                reflection->GetInt32(*mapping_proto, bank_descriptor) != current_controller_bank);
 }
+
+void MIDIMapper::refresh_highlights()
+{
+       receiver->clear_all_highlights();
+       update_highlights();
+}
+
+void MIDIMapper::refresh_lights()
+{
+       lock_guard<mutex> lock(mu);
+       update_lights_lock_held();
+}
+
+void MIDIMapper::update_highlights()
+{
+       if (num_subscribed_ports.load() == 0) {
+               receiver->clear_all_highlights();
+               return;
+       }
+
+       // Global controllers.
+       bool highlight_locut = false;
+       bool highlight_limiter_threshold = false;
+       bool highlight_makeup_gain = false;
+       bool highlight_toggle_limiter = false;
+       bool highlight_toggle_auto_makeup_gain = false;
+       for (size_t bus_idx = 0; bus_idx < size_t(mapping_proto->bus_mapping_size()); ++bus_idx) {
+               if (has_active_controller(
+                       bus_idx, MIDIMappingBusProto::kLocutFieldNumber, MIDIMappingProto::kLocutBankFieldNumber)) {
+                       highlight_locut = true;
+               }
+               if (has_active_controller(
+                       bus_idx, MIDIMappingBusProto::kLimiterThresholdFieldNumber, MIDIMappingProto::kLimiterThresholdBankFieldNumber)) {
+                       highlight_limiter_threshold = true;
+               }
+               if (has_active_controller(
+                       bus_idx, MIDIMappingBusProto::kMakeupGainFieldNumber, MIDIMappingProto::kMakeupGainBankFieldNumber)) {
+                       highlight_makeup_gain = true;
+               }
+               if (has_active_controller(
+                       bus_idx, MIDIMappingBusProto::kToggleLimiterFieldNumber, MIDIMappingProto::kToggleLimiterBankFieldNumber)) {
+                       highlight_toggle_limiter = true;
+               }
+               if (has_active_controller(
+                       bus_idx, MIDIMappingBusProto::kToggleAutoMakeupGainFieldNumber, MIDIMappingProto::kToggleAutoMakeupGainBankFieldNumber)) {
+                       highlight_toggle_auto_makeup_gain = true;
+               }
+       }
+       receiver->highlight_locut(highlight_locut);
+       receiver->highlight_limiter_threshold(highlight_limiter_threshold);
+       receiver->highlight_makeup_gain(highlight_makeup_gain);
+       receiver->highlight_toggle_limiter(highlight_toggle_limiter);
+       receiver->highlight_toggle_auto_makeup_gain(highlight_toggle_auto_makeup_gain);
+
+       // Per-bus controllers.
+       for (size_t bus_idx = 0; bus_idx < size_t(mapping_proto->bus_mapping_size()); ++bus_idx) {
+               receiver->highlight_stereo_width(bus_idx, has_active_controller(
+                       bus_idx, MIDIMappingBusProto::kStereoWidthFieldNumber, MIDIMappingProto::kStereoWidthBankFieldNumber));
+               receiver->highlight_treble(bus_idx, has_active_controller(
+                       bus_idx, MIDIMappingBusProto::kTrebleFieldNumber, MIDIMappingProto::kTrebleBankFieldNumber));
+               receiver->highlight_mid(bus_idx, has_active_controller(
+                       bus_idx, MIDIMappingBusProto::kMidFieldNumber, MIDIMappingProto::kMidBankFieldNumber));
+               receiver->highlight_bass(bus_idx, has_active_controller(
+                       bus_idx, MIDIMappingBusProto::kBassFieldNumber, MIDIMappingProto::kBassBankFieldNumber));
+               receiver->highlight_gain(bus_idx, has_active_controller(
+                       bus_idx, MIDIMappingBusProto::kGainFieldNumber, MIDIMappingProto::kGainBankFieldNumber));
+               receiver->highlight_compressor_threshold(bus_idx, has_active_controller(
+                       bus_idx, MIDIMappingBusProto::kCompressorThresholdFieldNumber, MIDIMappingProto::kCompressorThresholdBankFieldNumber));
+               receiver->highlight_fader(bus_idx, has_active_controller(
+                       bus_idx, MIDIMappingBusProto::kFaderFieldNumber, MIDIMappingProto::kFaderBankFieldNumber));
+               receiver->highlight_mute(bus_idx, has_active_controller(
+                       bus_idx, MIDIMappingBusProto::kToggleMuteFieldNumber, MIDIMappingProto::kToggleMuteBankFieldNumber));
+               receiver->highlight_toggle_locut(bus_idx, has_active_controller(
+                       bus_idx, MIDIMappingBusProto::kToggleLocutFieldNumber, MIDIMappingProto::kToggleLocutBankFieldNumber));
+               receiver->highlight_toggle_auto_gain_staging(bus_idx, has_active_controller(
+                       bus_idx, MIDIMappingBusProto::kToggleAutoGainStagingFieldNumber, MIDIMappingProto::kToggleAutoGainStagingBankFieldNumber));
+               receiver->highlight_toggle_compressor(bus_idx, has_active_controller(
+                       bus_idx, MIDIMappingBusProto::kToggleCompressorFieldNumber, MIDIMappingProto::kToggleCompressorBankFieldNumber));
+       }
+}
+
+void MIDIMapper::update_lights_lock_held()
+{
+       if (alsa_seq == nullptr || global_audio_mixer == nullptr) {
+               return;
+       }
+
+       set<unsigned> active_lights;  // Desired state.
+       if (current_controller_bank == 0) {
+               activate_lights_all_buses(MIDIMappingBusProto::kBank1IsSelectedFieldNumber, &active_lights);
+       }
+       if (current_controller_bank == 1) {
+               activate_lights_all_buses(MIDIMappingBusProto::kBank2IsSelectedFieldNumber, &active_lights);
+       }
+       if (current_controller_bank == 2) {
+               activate_lights_all_buses(MIDIMappingBusProto::kBank3IsSelectedFieldNumber, &active_lights);
+       }
+       if (current_controller_bank == 3) {
+               activate_lights_all_buses(MIDIMappingBusProto::kBank4IsSelectedFieldNumber, &active_lights);
+       }
+       if (current_controller_bank == 4) {
+               activate_lights_all_buses(MIDIMappingBusProto::kBank5IsSelectedFieldNumber, &active_lights);
+       }
+       if (global_audio_mixer->get_limiter_enabled()) {
+               activate_lights_all_buses(MIDIMappingBusProto::kLimiterIsOnFieldNumber, &active_lights);
+       }
+       if (global_audio_mixer->get_final_makeup_gain_auto()) {
+               activate_lights_all_buses(MIDIMappingBusProto::kAutoMakeupGainIsOnFieldNumber, &active_lights);
+       }
+       unsigned num_buses = min<unsigned>(global_audio_mixer->num_buses(), mapping_proto->bus_mapping_size());
+       for (unsigned bus_idx = 0; bus_idx < num_buses; ++bus_idx) {
+               if (global_audio_mixer->get_mute(bus_idx)) {
+                       activate_lights(bus_idx, MIDIMappingBusProto::kIsMutedFieldNumber, &active_lights);
+               }
+               if (global_audio_mixer->get_locut_enabled(bus_idx)) {
+                       activate_lights(bus_idx, MIDIMappingBusProto::kLocutIsOnFieldNumber, &active_lights);
+               }
+               if (global_audio_mixer->get_gain_staging_auto(bus_idx)) {
+                       activate_lights(bus_idx, MIDIMappingBusProto::kAutoGainStagingIsOnFieldNumber, &active_lights);
+               }
+               if (global_audio_mixer->get_compressor_enabled(bus_idx)) {
+                       activate_lights(bus_idx, MIDIMappingBusProto::kCompressorIsOnFieldNumber, &active_lights);
+               }
+               if (has_peaked[bus_idx]) {
+                       activate_lights(bus_idx, MIDIMappingBusProto::kHasPeakedFieldNumber, &active_lights);
+               }
+       }
+
+       unsigned num_events = 0;
+       for (unsigned note_num = 1; note_num <= 127; ++note_num) {
+               bool active = active_lights.count(note_num);
+               if (current_light_status.count(note_num) &&
+                   current_light_status[note_num] == active) {
+                       // Already known to be in the desired state.
+                       continue;
+               }
+
+               snd_seq_event_t ev;
+               snd_seq_ev_clear(&ev);
+
+               // Some devices drop events if we throw them onto them
+               // too quickly. Add a 1 ms delay for each.
+               snd_seq_real_time_t tm{0, num_events++ * 1000000};
+               snd_seq_ev_schedule_real(&ev, alsa_queue_id, true, &tm);
+               snd_seq_ev_set_source(&ev, 0);
+               snd_seq_ev_set_subs(&ev);
+
+               // For some reason, not all devices respond to note off.
+               // Use note-on with velocity of 0 (which is equivalent) instead.
+               snd_seq_ev_set_noteon(&ev, /*channel=*/0, note_num, active ? 127 : 0);
+               WARN_ON_ERROR("snd_seq_event_output", snd_seq_event_output(alsa_seq, &ev));
+               current_light_status[note_num] = active;
+       }
+       WARN_ON_ERROR("snd_seq_drain_output", snd_seq_drain_output(alsa_seq));
+}
+
+void MIDIMapper::activate_lights(unsigned bus_idx, int field_number, set<unsigned> *active_lights)
+{
+       const MIDIMappingBusProto &bus_mapping = mapping_proto->bus_mapping(bus_idx);
+
+       const FieldDescriptor *descriptor = bus_mapping.GetDescriptor()->FindFieldByNumber(field_number);
+       const Reflection *bus_reflection = bus_mapping.GetReflection();
+       if (!bus_reflection->HasField(bus_mapping, descriptor)) {
+               return;
+       }
+       const MIDILightProto &light_proto =
+               static_cast<const MIDILightProto &>(bus_reflection->GetMessage(bus_mapping, descriptor));
+       active_lights->insert(light_proto.note_number());
+}
+
+void MIDIMapper::activate_lights_all_buses(int field_number, set<unsigned> *active_lights)
+{
+       for (size_t bus_idx = 0; bus_idx < size_t(mapping_proto->bus_mapping_size()); ++bus_idx) {
+               const MIDIMappingBusProto &bus_mapping = mapping_proto->bus_mapping(bus_idx);
+
+               const FieldDescriptor *descriptor = bus_mapping.GetDescriptor()->FindFieldByNumber(field_number);
+               const Reflection *bus_reflection = bus_mapping.GetReflection();
+               if (!bus_reflection->HasField(bus_mapping, descriptor)) {
+                       continue;
+               }
+               const MIDILightProto &light_proto =
+                       static_cast<const MIDILightProto &>(bus_reflection->GetMessage(bus_mapping, descriptor));
+               active_lights->insert(light_proto.note_number());
+       }
+}