obs-studio/frontend/utility/MultitrackVideoOutput.cpp

#include "MultitrackVideoError.hpp"
#include "MultitrackVideoOutput.hpp"
#include "models/multitrack-video.hpp"
#include "GoLiveAPI_Network.hpp"
#include "GoLiveAPI_PostData.hpp"

#include <OBSApp.hpp>

#include <bpm.h>
#include <util/dstr.hpp>

#include <QPushButton>
#include <QMessageBox>
#include <QThread>
#include <QUrl>
#include <QUrlQuery>

#include <cinttypes>

Qt::ConnectionType BlockingConnectionTypeFor(QObject *object)
{
	return object->thread() == QThread::currentThread() ? Qt::DirectConnection : Qt::BlockingQueuedConnection;
}

bool MultitrackVideoDeveloperModeEnabled()
{
	static bool developer_mode = [] {
		auto args = qApp->arguments();
		for (const auto &arg : args) {
			if (arg == "--enable-multitrack-video-dev") {
				return true;
			}
		}
		return false;
	}();
	return developer_mode;
}

static OBSServiceAutoRelease create_service(const GoLiveApi::Config &go_live_config,
					    const std::optional<std::string> &rtmp_url, const QString &in_stream_key,
					    std::optional<bool> use_rtmps)
{
	const char *url = nullptr;
	QString stream_key = in_stream_key;

	const auto &ingest_endpoints = go_live_config.ingest_endpoints;

	for (auto &endpoint : ingest_endpoints) {
		if (qstrnicmp("RTMP", endpoint.protocol.c_str(), 4))
			continue;

		if (use_rtmps.has_value() && *use_rtmps != (qstricmp("RTMPS", endpoint.protocol.c_str()) == 0))
			continue;

		url = endpoint.url_template.c_str();
		if (endpoint.authentication && !endpoint.authentication->empty()) {
			blog(LOG_INFO, "Using stream key supplied by autoconfig");
			stream_key = QString::fromStdString(*endpoint.authentication);
		}
		break;
	}

	if (rtmp_url.has_value()) {
		// Despite being set by user, it was set to a ""
		if (rtmp_url->empty()) {
			throw MultitrackVideoError::warning(QTStr("FailedToStartStream.NoCustomRTMPURLInSettings"));
		}

		url = rtmp_url->c_str();
		blog(LOG_INFO, "Using custom RTMP URL: '%s'", url);
	} else {
		if (!url) {
			blog(LOG_ERROR, "No RTMP URL in go live config");
			throw MultitrackVideoError::warning(QTStr("FailedToStartStream.NoRTMPURLInConfig"));
		}

		blog(LOG_INFO, "Using URL template: '%s'", url);
	}

	DStr str;
	dstr_cat(str, url);

	// dstr_find does not protect against null, and dstr_cat will
	// not initialize str if cat'ing with a null url
	if (!dstr_is_empty(str)) {
		auto found = dstr_find(str, "/{stream_key}");
		if (found)
			dstr_remove(str, found - str->array, str->len - (found - str->array));
	}

	/* The stream key itself may contain query parameters, such as
	 * "bandwidthtest" that need to be carried over. */
	QUrl parsed_user_key{in_stream_key};
	QUrlQuery user_key_query{parsed_user_key};

	QUrl parsed_key{stream_key};

	QUrl parsed_url{url};
	QUrlQuery parsed_query{parsed_url};

	for (const auto &[key, value] : user_key_query.queryItems())
		parsed_query.addQueryItem(key, value);

	if (!go_live_config.meta.config_id.empty()) {
		parsed_query.addQueryItem("clientConfigId", QString::fromStdString(go_live_config.meta.config_id));
	}

	parsed_key.setQuery(parsed_query);

	OBSDataAutoRelease settings = obs_data_create();
	obs_data_set_string(settings, "server", str->array);
	obs_data_set_string(settings, "key", parsed_key.toString().toUtf8().constData());

	auto service = obs_service_create("rtmp_custom", "multitrack video service", settings, nullptr);

	if (!service) {
		blog(LOG_WARNING, "Failed to create multitrack video service");
		throw MultitrackVideoError::warning(QTStr("FailedToStartStream.FailedToCreateMultitrackVideoService"));
	}

	return service;
}

static OBSOutputAutoRelease create_output()
{
	OBSOutputAutoRelease output = obs_output_create("rtmp_output", "rtmp multitrack video", nullptr, nullptr);

	if (!output) {
		blog(LOG_ERROR, "Failed to create multitrack video rtmp output");
		throw MultitrackVideoError::warning(QTStr("FailedToStartStream.FailedToCreateMultitrackVideoOutput"));
	}

	return output;
}

static OBSOutputAutoRelease create_recording_output(obs_data_t *settings)
{
	OBSOutputAutoRelease output;
	bool useMP4 = obs_data_get_bool(settings, "use_mp4");

	if (useMP4) {
		output = obs_output_create("mp4_output", "mp4 multitrack video", settings, nullptr);
	} else {
		output = obs_output_create("flv_output", "flv multitrack video", settings, nullptr);
	}

	if (!output) {
		blog(LOG_ERROR, "Failed to create multitrack video %s output", useMP4 ? "mp4" : "flv");
	}

	return output;
}

static void adjust_video_encoder_scaling(const obs_video_info &ovi, obs_encoder_t *video_encoder,
					 const GoLiveApi::VideoEncoderConfiguration &encoder_config,
					 size_t encoder_index)
{
	auto requested_width = encoder_config.width;
	auto requested_height = encoder_config.height;

	if (ovi.base_width < requested_width || ovi.base_height < requested_height) {
		blog(LOG_WARNING,
		     "Requested resolution exceeds canvas/available resolution for encoder %zu: %" PRIu32 "x%" PRIu32
		     " > %" PRIu32 "x%" PRIu32,
		     encoder_index, requested_width, requested_height, ovi.base_width, ovi.base_height);
	}

	obs_encoder_set_scaled_size(video_encoder, requested_width, requested_height);
	obs_encoder_set_gpu_scale_type(video_encoder, encoder_config.gpu_scale_type.value_or(OBS_SCALE_BICUBIC));
	obs_encoder_set_preferred_video_format(video_encoder, encoder_config.format.value_or(VIDEO_FORMAT_NV12));
	obs_encoder_set_preferred_color_space(video_encoder, encoder_config.colorspace.value_or(VIDEO_CS_709));
	obs_encoder_set_preferred_range(video_encoder, encoder_config.range.value_or(VIDEO_RANGE_PARTIAL));
}

static uint32_t closest_divisor(const obs_video_info &ovi, const media_frames_per_second &target_fps)
{
	auto target = (uint64_t)target_fps.numerator * ovi.fps_den;
	auto source = (uint64_t)ovi.fps_num * target_fps.denominator;
	return std::max(1u, static_cast<uint32_t>(source / target));
}

static void adjust_encoder_frame_rate_divisor(const obs_video_info &ovi, obs_encoder_t *video_encoder,
					      const GoLiveApi::VideoEncoderConfiguration &encoder_config,
					      const size_t encoder_index)
{
	if (!encoder_config.framerate) {
		blog(LOG_WARNING, "`framerate` not specified for encoder %zu", encoder_index);
		return;
	}
	media_frames_per_second requested_fps = *encoder_config.framerate;

	if (ovi.fps_num == requested_fps.numerator && ovi.fps_den == requested_fps.denominator)
		return;

	auto divisor = closest_divisor(ovi, requested_fps);
	if (divisor <= 1)
		return;

	blog(LOG_INFO, "Setting frame rate divisor to %u for encoder %zu", divisor, encoder_index);
	obs_encoder_set_frame_rate_divisor(video_encoder, divisor);
}

static bool encoder_available(const char *type)
{
	const char *id = nullptr;

	for (size_t idx = 0; obs_enum_encoder_types(idx, &id); idx++) {
		if (strcmp(id, type) == 0)
			return true;
	}

	return false;
}

static OBSEncoderAutoRelease create_video_encoder(DStr &name_buffer, size_t encoder_index,
						  const GoLiveApi::VideoEncoderConfiguration &encoder_config)
{
	auto encoder_type = encoder_config.type.c_str();
	if (!encoder_available(encoder_type)) {
		blog(LOG_ERROR, "Encoder type '%s' not available", encoder_type);
		throw MultitrackVideoError::warning(QTStr("FailedToStartStream.EncoderNotAvailable").arg(encoder_type));
	}

	dstr_printf(name_buffer, "multitrack video video encoder %zu", encoder_index);

	OBSDataAutoRelease encoder_settings = obs_data_create_from_json(encoder_config.settings.dump().c_str());
	obs_data_set_bool(encoder_settings, "disable_scenecut", true);

	OBSEncoderAutoRelease video_encoder =
		obs_video_encoder_create(encoder_type, name_buffer, encoder_settings, nullptr);
	if (!video_encoder) {
		blog(LOG_ERROR, "Failed to create video encoder '%s'", name_buffer->array);
		throw MultitrackVideoError::warning(
			QTStr("FailedToStartStream.FailedToCreateVideoEncoder").arg(name_buffer->array, encoder_type));
	}
	obs_encoder_set_video(video_encoder, obs_get_video());

	obs_video_info ovi;
	if (!obs_get_video_info(&ovi)) {
		blog(LOG_WARNING, "Failed to get obs_video_info while creating encoder %zu", encoder_index);
		throw MultitrackVideoError::warning(
			QTStr("FailedToStartStream.FailedToGetOBSVideoInfo").arg(name_buffer->array, encoder_type));
	}

	adjust_video_encoder_scaling(ovi, video_encoder, encoder_config, encoder_index);
	adjust_encoder_frame_rate_divisor(ovi, video_encoder, encoder_config, encoder_index);

	return video_encoder;
}

static OBSEncoderAutoRelease create_audio_encoder(const char *name, const char *audio_encoder_id, obs_data_t *settings,
						  size_t mixer_idx)
{
	OBSEncoderAutoRelease audio_encoder =
		obs_audio_encoder_create(audio_encoder_id, name, settings, mixer_idx, nullptr);
	if (!audio_encoder) {
		blog(LOG_ERROR, "Failed to create audio encoder");
		throw MultitrackVideoError::warning(QTStr("FailedToStartStream.FailedToCreateAudioEncoder"));
	}
	obs_encoder_set_audio(audio_encoder, obs_get_audio());
	return audio_encoder;
}

struct OBSOutputs {
	OBSOutputAutoRelease output, recording_output;
};

static OBSOutputs SetupOBSOutput(QWidget *parent, const QString &multitrack_video_name,
				 obs_data_t *dump_stream_to_file_config, const GoLiveApi::Config &go_live_config,
				 std::vector<OBSEncoderAutoRelease> &audio_encoders,
				 std::shared_ptr<obs_encoder_group_t> &video_encoder_group,
				 const char *audio_encoder_id, size_t main_audio_mixer,
				 std::optional<size_t> vod_track_mixer);
static void SetupSignalHandlers(bool recording, MultitrackVideoOutput *self, obs_output_t *output, OBSSignal &start,
				OBSSignal &stop);

void MultitrackVideoOutput::PrepareStreaming(QWidget *parent, const char *service_name, obs_service_t *service,
					     const std::optional<std::string> &rtmp_url, const QString &stream_key,
					     const char *audio_encoder_id,
					     std::optional<uint32_t> maximum_aggregate_bitrate,
					     std::optional<uint32_t> maximum_video_tracks,
					     std::optional<std::string> custom_config,
					     obs_data_t *dump_stream_to_file_config, size_t main_audio_mixer,
					     std::optional<size_t> vod_track_mixer, std::optional<bool> use_rtmps)
{
	{
		const std::lock_guard<std::mutex> current_lock{current_mutex};
		const std::lock_guard<std::mutex> current_stream_dump_lock{current_stream_dump_mutex};
		if (current || current_stream_dump) {
			blog(LOG_WARNING, "Tried to prepare multitrack video output while it's already active");
			return;
		}
	}

	restart_on_error = false;

	std::optional<GoLiveApi::Config> go_live_config;
	std::optional<GoLiveApi::Config> custom;
	bool is_custom_config = custom_config.has_value();
	auto auto_config_url = MultitrackVideoAutoConfigURL(service);

	OBSDataAutoRelease service_settings = obs_service_get_settings(service);
	auto multitrack_video_name = QTStr("Basic.Settings.Stream.MultitrackVideoLabel");
	if (obs_data_has_user_value(service_settings, "multitrack_video_name")) {
		multitrack_video_name = obs_data_get_string(service_settings, "multitrack_video_name");
	}

	auto auto_config_url_data = auto_config_url.toUtf8();

	DStr vod_track_info_storage;
	if (vod_track_mixer.has_value())
		dstr_printf(vod_track_info_storage, "Yes (mixer: %zu)", vod_track_mixer.value());

	blog(LOG_INFO,
	     "Preparing enhanced broadcasting stream for:\n"
	     "    custom config:  %s\n"
	     "    config url:     %s\n"
	     "  settings:\n"
	     "    service:               %s\n"
	     "    max aggregate bitrate: %s (%" PRIu32 ")\n"
	     "    max video tracks:      %s (%" PRIu32 ")\n"
	     "    custom rtmp url:       %s ('%s')\n"
	     "    vod track:             %s",
	     is_custom_config ? "Yes" : "No", !auto_config_url.isEmpty() ? auto_config_url_data.constData() : "(null)",
	     service_name, maximum_aggregate_bitrate.has_value() ? "Set" : "Auto",
	     maximum_aggregate_bitrate.value_or(0), maximum_video_tracks.has_value() ? "Set" : "Auto",
	     maximum_video_tracks.value_or(0), rtmp_url.has_value() ? "Yes" : "No",
	     rtmp_url.has_value() ? rtmp_url->c_str() : "",
	     vod_track_info_storage->array ? vod_track_info_storage->array : "No");

	const bool custom_config_only = auto_config_url.isEmpty() && MultitrackVideoDeveloperModeEnabled() &&
					custom_config.has_value() &&
					strcmp(obs_service_get_id(service), "rtmp_custom") == 0;

	if (!custom_config_only) {
		auto go_live_post = constructGoLivePost(stream_key, maximum_aggregate_bitrate, maximum_video_tracks,
							vod_track_mixer.has_value());

		go_live_config = DownloadGoLiveConfig(parent, auto_config_url, go_live_post, multitrack_video_name);
	}

	if (custom_config.has_value()) {
		GoLiveApi::Config parsed_custom;
		try {
			parsed_custom = nlohmann::json::parse(*custom_config);
		} catch (const nlohmann::json::exception &exception) {
			blog(LOG_WARNING, "Failed to parse custom config: %s", exception.what());
			throw MultitrackVideoError::critical(QTStr("FailedToStartStream.InvalidCustomConfig"));
		}

		// copy unique ID from go live request
		if (go_live_config.has_value()) {
			parsed_custom.meta.config_id = go_live_config->meta.config_id;
			blog(LOG_INFO, "Using config_id from go live config with custom config: %s",
			     parsed_custom.meta.config_id.c_str());
		}

		nlohmann::json custom_data = parsed_custom;
		blog(LOG_INFO, "Using custom go live config: %s", custom_data.dump(4).c_str());

		custom.emplace(std::move(parsed_custom));
	}

	if (go_live_config.has_value()) {
		blog(LOG_INFO, "Enhanced broadcasting config_id: '%s'", go_live_config->meta.config_id.c_str());
	}

	if (!go_live_config && !custom) {
		blog(LOG_ERROR, "MultitrackVideoOutput: no config set, this should never happen");
		throw MultitrackVideoError::warning(QTStr("FailedToStartStream.NoConfig"));
	}

	const auto &output_config = custom ? *custom : *go_live_config;
	const auto &service_config = go_live_config ? *go_live_config : *custom;

	std::vector<OBSEncoderAutoRelease> audio_encoders;
	std::shared_ptr<obs_encoder_group_t> video_encoder_group;
	auto outputs = SetupOBSOutput(parent, multitrack_video_name, dump_stream_to_file_config, output_config,
				      audio_encoders, video_encoder_group, audio_encoder_id, main_audio_mixer,
				      vod_track_mixer);
	auto output = std::move(outputs.output);
	auto recording_output = std::move(outputs.recording_output);
	if (!output)
		throw MultitrackVideoError::warning(
			QTStr("FailedToStartStream.FallbackToDefault").arg(multitrack_video_name));

	auto multitrack_video_service = create_service(service_config, rtmp_url, stream_key, use_rtmps);
	if (!multitrack_video_service)
		throw MultitrackVideoError::warning(
			QTStr("FailedToStartStream.FallbackToDefault").arg(multitrack_video_name));

	obs_output_set_service(output, multitrack_video_service);

	// Register the BPM (Broadcast Performance Metrics) callback
	obs_output_add_packet_callback(output, bpm_inject, NULL);

	// Set callback to prevent reconnection attempts once the stream key has become invalid
	static auto reconnect_cb = [](void *, obs_output_t *, int code) -> bool {
		return code != OBS_OUTPUT_INVALID_STREAM;
	};
	obs_output_set_reconnect_callback(output, reconnect_cb, nullptr);

	OBSSignal start_streaming;
	OBSSignal stop_streaming;
	SetupSignalHandlers(false, this, output, start_streaming, stop_streaming);

	if (dump_stream_to_file_config && recording_output) {
		OBSSignal start_recording;
		OBSSignal stop_recording;
		SetupSignalHandlers(true, this, recording_output, start_recording, stop_recording);

		decltype(audio_encoders) recording_audio_encoders;
		recording_audio_encoders.reserve(audio_encoders.size());
		for (auto &encoder : audio_encoders) {
			recording_audio_encoders.emplace_back(obs_encoder_get_ref(encoder));
		}

		{
			const std::lock_guard current_stream_dump_lock{current_stream_dump_mutex};
			current_stream_dump.emplace(OBSOutputObjects{
				std::move(recording_output),
				video_encoder_group,
				std::move(recording_audio_encoders),
				nullptr,
				std::move(start_recording),
				std::move(stop_recording),
			});
		}
	}

	const std::lock_guard current_lock{current_mutex};
	current.emplace(OBSOutputObjects{
		std::move(output),
		video_encoder_group,
		std::move(audio_encoders),
		std::move(multitrack_video_service),
		std::move(start_streaming),
		std::move(stop_streaming),
	});
}

signal_handler_t *MultitrackVideoOutput::StreamingSignalHandler()
{
	const std::lock_guard current_lock{current_mutex};
	return current.has_value() ? obs_output_get_signal_handler(current->output_) : nullptr;
}

void MultitrackVideoOutput::StartedStreaming()
{
	OBSOutputAutoRelease dump_output;
	{
		const std::lock_guard current_stream_dump_lock{current_stream_dump_mutex};
		if (current_stream_dump && current_stream_dump->output_) {
			dump_output = obs_output_get_ref(current_stream_dump->output_);
		}
	}

	if (!dump_output)
		return;

	auto result = obs_output_start(dump_output);
	blog(LOG_INFO, "MultitrackVideoOutput: starting recording%s", result ? "" : " failed");
}

void MultitrackVideoOutput::StopStreaming()
{
	restart_on_error = false;

	OBSOutputAutoRelease current_output;
	{
		const std::lock_guard current_lock{current_mutex};
		if (current && current->output_)
			current_output = obs_output_get_ref(current->output_);
	}
	if (current_output)
		obs_output_stop(current_output);

	OBSOutputAutoRelease dump_output;
	{
		const std::lock_guard current_stream_dump_lock{current_stream_dump_mutex};
		if (current_stream_dump && current_stream_dump->output_)
			dump_output = obs_output_get_ref(current_stream_dump->output_);
	}
	if (dump_output)
		obs_output_stop(dump_output);
}

bool MultitrackVideoOutput::HandleIncompatibleSettings(QWidget *parent, config_t *config, obs_service_t *service,
						       bool &useDelay, bool &enableNewSocketLoop,
						       bool &enableDynBitrate)
{
	QString incompatible_settings;
	QString where_to_disable;
	QString incompatible_settings_list;

	size_t num = 1;

	auto check_setting = [&](bool setting, const char *name, const char *section) {
		if (!setting)
			return;

		incompatible_settings += QString(" %1. %2\n").arg(num).arg(QTStr(name));

		where_to_disable += QString(" %1. [%2 → %3 → %4]\n")
					    .arg(num)
					    .arg(QTStr("Settings"))
					    .arg(QTStr("Basic.Settings.Advanced"))
					    .arg(QTStr(section));

		incompatible_settings_list += QString("%1, ").arg(name);

		num += 1;
	};

	check_setting(useDelay, "Basic.Settings.Advanced.StreamDelay", "Basic.Settings.Advanced.StreamDelay");
#ifdef _WIN32
	check_setting(enableNewSocketLoop, "Basic.Settings.Advanced.Network.EnableNewSocketLoop",
		      "Basic.Settings.Advanced.Network");
#endif
	check_setting(enableDynBitrate, "Basic.Settings.Output.DynamicBitrate.Beta", "Basic.Settings.Advanced.Network");

	if (incompatible_settings.isEmpty())
		return true;

	OBSDataAutoRelease service_settings = obs_service_get_settings(service);

	QMessageBox mb(parent);
	mb.setIcon(QMessageBox::Critical);
	mb.setWindowTitle(QTStr("MultitrackVideo.IncompatibleSettings.Title"));
	mb.setText(QString(QTStr("MultitrackVideo.IncompatibleSettings.Text"))
			   .arg(obs_data_get_string(service_settings, "multitrack_video_name"))
			   .arg(incompatible_settings)
			   .arg(where_to_disable));
	auto this_stream = mb.addButton(QTStr("MultitrackVideo.IncompatibleSettings.DisableAndStartStreaming"),
					QMessageBox::AcceptRole);
	auto all_streams = mb.addButton(QString(QTStr("MultitrackVideo.IncompatibleSettings.UpdateAndStartStreaming")),
					QMessageBox::AcceptRole);
	mb.setStandardButtons(QMessageBox::StandardButton::Cancel);

	mb.exec();

	const char *action = "cancel";
	if (mb.clickedButton() == this_stream) {
		action = "DisableAndStartStreaming";
	} else if (mb.clickedButton() == all_streams) {
		action = "UpdateAndStartStreaming";
	}

	blog(LOG_INFO,
	     "MultitrackVideoOutput: attempted to start stream with incompatible"
	     "settings (%s); action taken: %s",
	     incompatible_settings_list.toUtf8().constData(), action);

	if (mb.clickedButton() == this_stream || mb.clickedButton() == all_streams) {
		useDelay = false;
		enableNewSocketLoop = false;
		enableDynBitrate = false;

		if (mb.clickedButton() == all_streams) {
			config_set_bool(config, "Output", "DelayEnable", false);
#ifdef _WIN32
			config_set_bool(config, "Output", "NewSocketLoopEnable", false);
#endif
			config_set_bool(config, "Output", "DynamicBitrate", false);
		}

		return true;
	}

	MultitrackVideoOutput::ReleaseOnMainThread(take_current());
	MultitrackVideoOutput::ReleaseOnMainThread(take_current_stream_dump());

	return false;
}

static bool create_video_encoders(const GoLiveApi::Config &go_live_config,
				  std::shared_ptr<obs_encoder_group_t> &video_encoder_group, obs_output_t *output,
				  obs_output_t *recording_output)
{
	DStr video_encoder_name_buffer;
	if (go_live_config.encoder_configurations.empty()) {
		blog(LOG_WARNING, "MultitrackVideoOutput: Missing video encoder configurations");
		throw MultitrackVideoError::warning(QTStr("FailedToStartStream.MissingEncoderConfigs"));
	}

	std::shared_ptr<obs_encoder_group_t> encoder_group(obs_encoder_group_create(), obs_encoder_group_destroy);
	if (!encoder_group)
		return false;

	for (size_t i = 0; i < go_live_config.encoder_configurations.size(); i++) {
		auto encoder =
			create_video_encoder(video_encoder_name_buffer, i, go_live_config.encoder_configurations[i]);
		if (!encoder)
			return false;

		if (!obs_encoder_set_group(encoder, encoder_group.get()))
			return false;

		obs_output_set_video_encoder2(output, encoder, i);
		if (recording_output)
			obs_output_set_video_encoder2(recording_output, encoder, i);
	}

	video_encoder_group = encoder_group;
	return true;
}

static void create_audio_encoders(const GoLiveApi::Config &go_live_config,
				  std::vector<OBSEncoderAutoRelease> &audio_encoders, obs_output_t *output,
				  obs_output_t *recording_output, const char *audio_encoder_id, size_t main_audio_mixer,
				  std::optional<size_t> vod_track_mixer, std::vector<speaker_layout> &speaker_layouts,
				  speaker_layout &current_layout)
{
	speaker_layout speakers = SPEAKERS_UNKNOWN;
	obs_audio_info oai = {};
	if (obs_get_audio_info(&oai))
		speakers = oai.speakers;

	current_layout = speakers;

	auto sanitize_audio_channels = [&](obs_encoder_t *encoder, uint32_t channels) {
		speaker_layout target_speakers = SPEAKERS_UNKNOWN;
		for (size_t i = 0; i <= (size_t)SPEAKERS_7POINT1; i++) {
			if (get_audio_channels((speaker_layout)i) != channels)
				continue;

			target_speakers = (speaker_layout)i;
			break;
		}
		if (target_speakers == SPEAKERS_UNKNOWN) {
			blog(LOG_WARNING,
			     "MultitrackVideoOutput: Could not find "
			     "speaker layout for %" PRIu32 "channels "
			     "while configuring encoder '%s'",
			     channels, obs_encoder_get_name(encoder));
			return;
		}
		if (speakers != SPEAKERS_UNKNOWN &&
		    (channels > get_audio_channels(speakers) || speakers == target_speakers))
			return;

		auto it = std::find(std::begin(speaker_layouts), std::end(speaker_layouts), target_speakers);
		if (it == std::end(speaker_layouts))
			speaker_layouts.push_back(target_speakers);
	};

	using encoder_configs_type = decltype(go_live_config.audio_configurations.live);
	DStr encoder_name_buffer;
	size_t output_encoder_index = 0;

	auto create_encoders = [&](const char *name_prefix, const encoder_configs_type &configs, size_t mixer_idx) {
		if (configs.empty()) {
			blog(LOG_WARNING, "MultitrackVideoOutput: Missing audio encoder configurations (for '%s')",
			     name_prefix);
			throw MultitrackVideoError::warning(QTStr("FailedToStartStream.MissingEncoderConfigs"));
		}

		for (size_t i = 0; i < configs.size(); i++) {
			dstr_printf(encoder_name_buffer, "%s %zu", name_prefix, i);
			OBSDataAutoRelease settings = obs_data_create_from_json(configs[i].settings.dump().c_str());
			OBSEncoderAutoRelease audio_encoder =
				create_audio_encoder(encoder_name_buffer->array, audio_encoder_id, settings, mixer_idx);

			sanitize_audio_channels(audio_encoder, configs[i].channels);

			obs_output_set_audio_encoder(output, audio_encoder, output_encoder_index);
			if (recording_output)
				obs_output_set_audio_encoder(recording_output, audio_encoder, output_encoder_index);
			output_encoder_index += 1;
			audio_encoders.emplace_back(std::move(audio_encoder));
		}
	};

	create_encoders("multitrack video live audio", go_live_config.audio_configurations.live, main_audio_mixer);

	if (!vod_track_mixer.has_value())
		return;

	// we already check for empty inside of `create_encoders`
	encoder_configs_type empty = {};
	create_encoders("multitrack video vod audio", go_live_config.audio_configurations.vod.value_or(empty),
			*vod_track_mixer);

	return;
}

static const char *speaker_layout_to_string(speaker_layout layout)
{
	switch (layout) {
	case SPEAKERS_MONO:
		return "Mono";
	case SPEAKERS_2POINT1:
		return "2.1";
	case SPEAKERS_4POINT0:
		return "4.0";
	case SPEAKERS_4POINT1:
		return "4.1";
	case SPEAKERS_5POINT1:
		return "5.1";
	case SPEAKERS_7POINT1:
		return "7.1";
	case SPEAKERS_UNKNOWN:
	case SPEAKERS_STEREO:
		return "Stereo";
	}

	return "Stereo";
}

static void handle_speaker_layout_issues(QWidget *parent, const QString &multitrack_video_name,
					 const std::vector<speaker_layout> &requested_layouts, speaker_layout layout)
{
	if (requested_layouts.empty())
		return;

	QString message;
	if (requested_layouts.size() == 1) {
		message = QTStr("MultitrackVideo.IncompatibleSettings.AudioChannelsSingle")
				  .arg(QTStr(speaker_layout_to_string(requested_layouts.front())));
	} else {
		message =
			QTStr("MultitrackVideo.IncompatibleSettings.AudioChannelsMultiple").arg(multitrack_video_name);
	}

	QMetaObject::invokeMethod(
		parent,
		[&] {
			QMessageBox mb(parent);
			mb.setIcon(QMessageBox::Critical);
			mb.setWindowTitle(QTStr("MultitrackVideo.IncompatibleSettings.Title"));
			mb.setText(QTStr("MultitrackVideo.IncompatibleSettings.AudioChannels")
					   .arg(multitrack_video_name)
					   .arg(QTStr(speaker_layout_to_string(layout)))
					   .arg(message));

			mb.setStandardButtons(QMessageBox::StandardButton::Cancel);

			mb.exec();
		},
		BlockingConnectionTypeFor(parent));

	blog(LOG_INFO, "MultitrackVideoOutput: Attempted to start stream with incompatible "
		       "audio channel setting. Action taken: cancel");

	throw MultitrackVideoError::cancel();
}

static OBSOutputs SetupOBSOutput(QWidget *parent, const QString &multitrack_video_name,
				 obs_data_t *dump_stream_to_file_config, const GoLiveApi::Config &go_live_config,
				 std::vector<OBSEncoderAutoRelease> &audio_encoders,
				 std::shared_ptr<obs_encoder_group_t> &video_encoder_group,
				 const char *audio_encoder_id, size_t main_audio_mixer,
				 std::optional<size_t> vod_track_mixer)
{
	auto output = create_output();
	OBSOutputAutoRelease recording_output;
	if (dump_stream_to_file_config)
		recording_output = create_recording_output(dump_stream_to_file_config);

	if (!create_video_encoders(go_live_config, video_encoder_group, output, recording_output))
		return {nullptr, nullptr};

	std::vector<speaker_layout> requested_speaker_layouts;
	speaker_layout current_layout = SPEAKERS_UNKNOWN;
	create_audio_encoders(go_live_config, audio_encoders, output, recording_output, audio_encoder_id,
			      main_audio_mixer, vod_track_mixer, requested_speaker_layouts, current_layout);

	handle_speaker_layout_issues(parent, multitrack_video_name, requested_speaker_layouts, current_layout);

	return {std::move(output), std::move(recording_output)};
}

void SetupSignalHandlers(bool recording, MultitrackVideoOutput *self, obs_output_t *output, OBSSignal &start,
			 OBSSignal &stop)
{
	auto handler = obs_output_get_signal_handler(output);

	start.Connect(handler, "start", !recording ? StreamStartHandler : RecordingStartHandler, self);

	stop.Connect(handler, "stop", !recording ? StreamStopHandler : RecordingStopHandler, self);
}

std::optional<MultitrackVideoOutput::OBSOutputObjects> MultitrackVideoOutput::take_current()
{
	const std::lock_guard<std::mutex> current_lock{current_mutex};
	auto val = std::move(current);
	current.reset();
	return val;
}

std::optional<MultitrackVideoOutput::OBSOutputObjects> MultitrackVideoOutput::take_current_stream_dump()
{
	const std::lock_guard<std::mutex> current_stream_dump_lock{current_stream_dump_mutex};
	auto val = std::move(current_stream_dump);
	current_stream_dump.reset();
	return val;
}

void MultitrackVideoOutput::ReleaseOnMainThread(std::optional<OBSOutputObjects> objects)
{

	if (!objects.has_value())
		return;

	QMetaObject::invokeMethod(
		QApplication::instance()->thread(), [objects = std::move(objects)] {}, Qt::QueuedConnection);
}

void StreamStartHandler(void *arg, calldata_t *)
{
	auto self = static_cast<MultitrackVideoOutput *>(arg);
	self->restart_on_error = true;
}

void StreamStopHandler(void *arg, calldata_t *data)
{
	auto self = static_cast<MultitrackVideoOutput *>(arg);

	OBSOutputAutoRelease stream_dump_output;
	{
		const std::lock_guard<std::mutex> current_stream_dump_lock{self->current_stream_dump_mutex};
		if (self->current_stream_dump && self->current_stream_dump->output_)
			stream_dump_output = obs_output_get_ref(self->current_stream_dump->output_);
	}
	if (stream_dump_output)
		obs_output_stop(stream_dump_output);

	/* Unregister the BPM (Broadcast Performance Metrics) callback and destroy the allocated metrics data. */
	obs_output_remove_packet_callback(static_cast<obs_output_t *>(calldata_ptr(data, "output")), bpm_inject, NULL);
	bpm_destroy(static_cast<obs_output_t *>(calldata_ptr(data, "output")));

	MultitrackVideoOutput::ReleaseOnMainThread(self->take_current());
}

void RecordingStartHandler(void * /* arg */, calldata_t * /* data */)
{
	blog(LOG_INFO, "MultitrackVideoOutput: recording started");
}

void RecordingStopHandler(void *arg, calldata_t *)
{
	auto self = static_cast<MultitrackVideoOutput *>(arg);
	blog(LOG_INFO, "MultitrackVideoOutput: recording stopped");
	MultitrackVideoOutput::ReleaseOnMainThread(self->take_current_stream_dump());
}