Implement BPM support

Based on #62896, only implements the BPM support part.

* Implements BPM support in the AudioStreamOGG/MP3 importers.
* Can select BPM/Bar Size and total beats in a song file, as well as edit looping points.
* Looping is now BPM aware
* Added a special importer UI for configuring this.
* Added a special preview showing the audio waveform as well as the playback position in the resource picker.
* Renamed `AudioStream::instance` to `instantiate` for correctness.

13 files changed, 361 insertions, 42 deletions

diff --git a/modules/minimp3/audio_stream_mp3.cpp b/modules/minimp3/audio_stream_mp3.cpp
index c37bea519f..98bcdea8f4 100644
--- a/modules/minimp3/audio_stream_mp3.cpp
+++ b/modules/minimp3/audio_stream_mp3.cpp
@@ -46,6 +46,12 @@ int AudioStreamPlaybackMP3::_mix_internal(AudioFrame *p_buffer, int p_frames) {
 
 	int frames_mixed_this_step = p_frames;
 
+	int beat_length_frames = -1;
+	bool beat_loop = mp3_stream->has_loop() && mp3_stream->get_bpm() > 0 && mp3_stream->get_beat_count() > 0;
+	if (beat_loop) {
+		beat_length_frames = mp3_stream->get_beat_count() * mp3_stream->sample_rate * 60 / mp3_stream->get_bpm();
+	}
+
 	while (todo && active) {
 		mp3dec_frame_info_t frame_info;
 		mp3d_sample_t *buf_frame = nullptr;
@@ -54,8 +60,25 @@ int AudioStreamPlaybackMP3::_mix_internal(AudioFrame *p_buffer, int p_frames) {
 
 		if (samples_mixed) {
 			p_buffer[p_frames - todo] = AudioFrame(buf_frame[0], buf_frame[samples_mixed - 1]);
+			if (loop_fade_remaining < FADE_SIZE) {
+				p_buffer[p_frames - todo] += loop_fade[loop_fade_remaining] * (float(FADE_SIZE - loop_fade_remaining) / float(FADE_SIZE));
+				loop_fade_remaining++;
+			}
 			--todo;
 			++frames_mixed;
+
+			if (beat_loop && (int)frames_mixed >= beat_length_frames) {
+				for (int i = 0; i < FADE_SIZE; i++) {
+					samples_mixed = mp3dec_ex_read_frame(mp3d, &buf_frame, &frame_info, mp3_stream->channels);
+					loop_fade[i] = AudioFrame(buf_frame[0], buf_frame[samples_mixed - 1]);
+					if (!samples_mixed) {
+						break;
+					}
+				}
+				loop_fade_remaining = 0;
+				seek(mp3_stream->loop_offset);
+				loops++;
+			}
 		}
 
 		else {
@@ -117,6 +140,10 @@ void AudioStreamPlaybackMP3::seek(float p_time) {
 	mp3dec_ex_seek(mp3d, (uint64_t)frames_mixed * mp3_stream->channels);
 }
 
+void AudioStreamPlaybackMP3::tag_used_streams() {
+	mp3_stream->tag_used(get_playback_position());
+}
+
 AudioStreamPlaybackMP3::~AudioStreamPlaybackMP3() {
 	if (mp3d) {
 		mp3dec_ex_close(mp3d);
@@ -124,7 +151,7 @@ AudioStreamPlaybackMP3::~AudioStreamPlaybackMP3() {
 	}
 }
 
-Ref<AudioStreamPlayback> AudioStreamMP3::instance_playback() {
+Ref<AudioStreamPlayback> AudioStreamMP3::instantiate_playback() {
 	Ref<AudioStreamPlaybackMP3> mp3s;
 
 	ERR_FAIL_COND_V_MSG(data.is_empty(), mp3s,
@@ -206,6 +233,36 @@ bool AudioStreamMP3::is_monophonic() const {
 	return false;
 }
 
+void AudioStreamMP3::set_bpm(double p_bpm) {
+	ERR_FAIL_COND(p_bpm < 0);
+	bpm = p_bpm;
+	emit_changed();
+}
+
+double AudioStreamMP3::get_bpm() const {
+	return bpm;
+}
+
+void AudioStreamMP3::set_beat_count(int p_beat_count) {
+	ERR_FAIL_COND(p_beat_count < 0);
+	beat_count = p_beat_count;
+	emit_changed();
+}
+
+int AudioStreamMP3::get_beat_count() const {
+	return beat_count;
+}
+
+void AudioStreamMP3::set_bar_beats(int p_bar_beats) {
+	ERR_FAIL_COND(p_bar_beats < 0);
+	bar_beats = p_bar_beats;
+	emit_changed();
+}
+
+int AudioStreamMP3::get_bar_beats() const {
+	return bar_beats;
+}
+
 void AudioStreamMP3::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("set_data", "data"), &AudioStreamMP3::set_data);
 	ClassDB::bind_method(D_METHOD("get_data"), &AudioStreamMP3::get_data);
@@ -216,7 +273,19 @@ void AudioStreamMP3::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("set_loop_offset", "seconds"), &AudioStreamMP3::set_loop_offset);
 	ClassDB::bind_method(D_METHOD("get_loop_offset"), &AudioStreamMP3::get_loop_offset);
 
+	ClassDB::bind_method(D_METHOD("set_bpm", "bpm"), &AudioStreamMP3::set_bpm);
+	ClassDB::bind_method(D_METHOD("get_bpm"), &AudioStreamMP3::get_bpm);
+
+	ClassDB::bind_method(D_METHOD("set_beat_count", "count"), &AudioStreamMP3::set_beat_count);
+	ClassDB::bind_method(D_METHOD("get_beat_count"), &AudioStreamMP3::get_beat_count);
+
+	ClassDB::bind_method(D_METHOD("set_bar_beats", "count"), &AudioStreamMP3::set_bar_beats);
+	ClassDB::bind_method(D_METHOD("get_bar_beats"), &AudioStreamMP3::get_bar_beats);
+
 	ADD_PROPERTY(PropertyInfo(Variant::PACKED_BYTE_ARRAY, "data", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_NO_EDITOR), "set_data", "get_data");
+	ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "bpm", PROPERTY_HINT_RANGE, "0,400,0.01,or_greater"), "set_bpm", "get_bpm");
+	ADD_PROPERTY(PropertyInfo(Variant::INT, "beat_count", PROPERTY_HINT_RANGE, "0,512,1,or_greater"), "set_beat_count", "get_beat_count");
+	ADD_PROPERTY(PropertyInfo(Variant::INT, "bar_beats", PROPERTY_HINT_RANGE, "2,32,1,or_greater"), "set_bar_beats", "get_bar_beats");
 	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "loop"), "set_loop", "has_loop");
 	ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "loop_offset"), "set_loop_offset", "get_loop_offset");
 }
diff --git a/modules/minimp3/audio_stream_mp3.h b/modules/minimp3/audio_stream_mp3.h
index c1a60ddccb..428ac1240e 100644
--- a/modules/minimp3/audio_stream_mp3.h
+++ b/modules/minimp3/audio_stream_mp3.h
@@ -41,6 +41,12 @@ class AudioStreamMP3;
 class AudioStreamPlaybackMP3 : public AudioStreamPlaybackResampled {
 	GDCLASS(AudioStreamPlaybackMP3, AudioStreamPlaybackResampled);
 
+	enum {
+		FADE_SIZE = 256
+	};
+	AudioFrame loop_fade[FADE_SIZE];
+	int loop_fade_remaining = FADE_SIZE;
+
 	mp3dec_ex_t *mp3d = nullptr;
 	uint32_t frames_mixed = 0;
 	bool active = false;
@@ -64,6 +70,8 @@ public:
 	virtual float get_playback_position() const override;
 	virtual void seek(float p_time) override;
 
+	virtual void tag_used_streams() override;
+
 	AudioStreamPlaybackMP3() {}
 	~AudioStreamPlaybackMP3();
 };
@@ -85,17 +93,30 @@ class AudioStreamMP3 : public AudioStream {
 	float loop_offset = 0.0;
 	void clear_data();
 
+	double bpm = 0;
+	int beat_count = 0;
+	int bar_beats = 4;
+
 protected:
 	static void _bind_methods();
 
 public:
 	void set_loop(bool p_enable);
-	bool has_loop() const;
+	virtual bool has_loop() const override;
 
 	void set_loop_offset(float p_seconds);
 	float get_loop_offset() const;
 
-	virtual Ref<AudioStreamPlayback> instance_playback() override;
+	void set_bpm(double p_bpm);
+	virtual double get_bpm() const override;
+
+	void set_beat_count(int p_beat_count);
+	virtual int get_beat_count() const override;
+
+	void set_bar_beats(int p_bar_beats);
+	virtual int get_bar_beats() const override;
+
+	virtual Ref<AudioStreamPlayback> instantiate_playback() override;
 	virtual String get_stream_name() const override;
 
 	void set_data(const Vector<uint8_t> &p_data);
diff --git a/modules/minimp3/doc_classes/AudioStreamMP3.xml b/modules/minimp3/doc_classes/AudioStreamMP3.xml
index 404f6c31e5..8f03681c06 100644
--- a/modules/minimp3/doc_classes/AudioStreamMP3.xml
+++ b/modules/minimp3/doc_classes/AudioStreamMP3.xml
@@ -9,6 +9,12 @@
 	<tutorials>
 	</tutorials>
 	<members>
+		<member name="bar_beats" type="int" setter="set_bar_beats" getter="get_bar_beats" default="4">
+		</member>
+		<member name="beat_count" type="int" setter="set_beat_count" getter="get_beat_count" default="0">
+		</member>
+		<member name="bpm" type="float" setter="set_bpm" getter="get_bpm" default="0.0">
+		</member>
 		<member name="data" type="PackedByteArray" setter="set_data" getter="get_data" default="PackedByteArray()">
 			Contains the audio data in bytes.
 			You can load a file without having to import it beforehand using the code snippet below. Keep in mind that this snippet loads the whole file into memory and may not be ideal for huge files (hundreds of megabytes or more).
diff --git a/modules/minimp3/resource_importer_mp3.cpp b/modules/minimp3/resource_importer_mp3.cpp
index e03940f963..8526aeef38 100644
--- a/modules/minimp3/resource_importer_mp3.cpp
+++ b/modules/minimp3/resource_importer_mp3.cpp
@@ -34,6 +34,10 @@
 #include "core/io/resource_saver.h"
 #include "scene/resources/texture.h"
 
+#ifdef TOOLS_ENABLED
+#include "editor/import/audio_stream_import_settings.h"
+#endif
+
 String ResourceImporterMP3::get_importer_name() const {
 	return "mp3";
 }
@@ -69,14 +73,26 @@ String ResourceImporterMP3::get_preset_name(int p_idx) const {
 void ResourceImporterMP3::get_import_options(const String &p_path, List<ImportOption> *r_options, int p_preset) const {
 	r_options->push_back(ImportOption(PropertyInfo(Variant::BOOL, "loop"), true));
 	r_options->push_back(ImportOption(PropertyInfo(Variant::FLOAT, "loop_offset"), 0));
+	r_options->push_back(ImportOption(PropertyInfo(Variant::FLOAT, "bpm", PROPERTY_HINT_RANGE, "0,400,0.01,or_greater"), 0));
+	r_options->push_back(ImportOption(PropertyInfo(Variant::INT, "beat_count", PROPERTY_HINT_RANGE, "0,512,or_greater"), 0));
+	r_options->push_back(ImportOption(PropertyInfo(Variant::INT, "bar_beats", PROPERTY_HINT_RANGE, "2,32,or_greater"), 4));
 }
 
-Error ResourceImporterMP3::import(const String &p_source_file, const String &p_save_path, const HashMap<StringName, Variant> &p_options, List<String> *r_platform_variants, List<String> *r_gen_files, Variant *r_metadata) {
-	bool loop = p_options["loop"];
-	float loop_offset = p_options["loop_offset"];
+#ifdef TOOLS_ENABLED
+bool ResourceImporterMP3::has_advanced_options() const {
+	return true;
+}
+void ResourceImporterMP3::show_advanced_options(const String &p_path) {
+	Ref<AudioStreamMP3> mp3_stream = import_mp3(p_path);
+	if (mp3_stream.is_valid()) {
+		AudioStreamImportSettings::get_singleton()->edit(p_path, "mp3", mp3_stream);
+	}
+}
+#endif
 
-	Ref<FileAccess> f = FileAccess::open(p_source_file, FileAccess::READ);
-	ERR_FAIL_COND_V(f.is_null(), ERR_CANT_OPEN);
+Ref<AudioStreamMP3> ResourceImporterMP3::import_mp3(const String &p_path) {
+	Ref<FileAccess> f = FileAccess::open(p_path, FileAccess::READ);
+	ERR_FAIL_COND_V(f.is_null(), Ref<AudioStreamMP3>());
 
 	uint64_t len = f->get_length();
 
@@ -90,9 +106,27 @@ Error ResourceImporterMP3::import(const String &p_source_file, const String &p_s
 	mp3_stream.instantiate();
 
 	mp3_stream->set_data(data);
-	ERR_FAIL_COND_V(!mp3_stream->get_data().size(), ERR_FILE_CORRUPT);
+	ERR_FAIL_COND_V(!mp3_stream->get_data().size(), Ref<AudioStreamMP3>());
+
+	return mp3_stream;
+}
+
+Error ResourceImporterMP3::import(const String &p_source_file, const String &p_save_path, const HashMap<StringName, Variant> &p_options, List<String> *r_platform_variants, List<String> *r_gen_files, Variant *r_metadata) {
+	bool loop = p_options["loop"];
+	float loop_offset = p_options["loop_offset"];
+	double bpm = p_options["bpm"];
+	float beat_count = p_options["beat_count"];
+	float bar_beats = p_options["bar_beats"];
+
+	Ref<AudioStreamMP3> mp3_stream = import_mp3(p_source_file);
+	if (mp3_stream.is_null()) {
+		return ERR_CANT_OPEN;
+	}
 	mp3_stream->set_loop(loop);
 	mp3_stream->set_loop_offset(loop_offset);
+	mp3_stream->set_bpm(bpm);
+	mp3_stream->set_beat_count(beat_count);
+	mp3_stream->set_bar_beats(bar_beats);
 
 	return ResourceSaver::save(p_save_path + ".mp3str", mp3_stream);
 }
diff --git a/modules/minimp3/resource_importer_mp3.h b/modules/minimp3/resource_importer_mp3.h
index 678a3773bb..38729d68f8 100644
--- a/modules/minimp3/resource_importer_mp3.h
+++ b/modules/minimp3/resource_importer_mp3.h
@@ -50,6 +50,12 @@ public:
 	virtual void get_import_options(const String &p_path, List<ImportOption> *r_options, int p_preset = 0) const override;
 	virtual bool get_option_visibility(const String &p_path, const String &p_option, const HashMap<StringName, Variant> &p_options) const override;
 
+#ifdef TOOLS_ENABLED
+	virtual bool has_advanced_options() const override;
+	virtual void show_advanced_options(const String &p_path) override;
+#endif
+	static Ref<AudioStreamMP3> import_mp3(const String &p_path);
+
 	virtual Error import(const String &p_source_file, const String &p_save_path, const HashMap<StringName, Variant> &p_options, List<String> *r_platform_variants, List<String> *r_gen_files = nullptr, Variant *r_metadata = nullptr) override;
 
 	ResourceImporterMP3();
diff --git a/modules/ogg/ogg_packet_sequence.cpp b/modules/ogg/ogg_packet_sequence.cpp
index da52ecfdd5..e18fa9e590 100644
--- a/modules/ogg/ogg_packet_sequence.cpp
+++ b/modules/ogg/ogg_packet_sequence.cpp
@@ -106,7 +106,7 @@ float OGGPacketSequence::get_length() const {
 	return granule_pos / sampling_rate;
 }
 
-Ref<OGGPacketSequencePlayback> OGGPacketSequence::instance_playback() {
+Ref<OGGPacketSequencePlayback> OGGPacketSequence::instantiate_playback() {
 	Ref<OGGPacketSequencePlayback> playback;
 	playback.instantiate();
 	playback->ogg_packet_sequence = Ref<OGGPacketSequence>(this);
diff --git a/modules/ogg/ogg_packet_sequence.h b/modules/ogg/ogg_packet_sequence.h
index 73e3cb4fff..76b673c6ac 100644
--- a/modules/ogg/ogg_packet_sequence.h
+++ b/modules/ogg/ogg_packet_sequence.h
@@ -86,7 +86,7 @@ public:
 	// Returns the granule position of the last page in this sequence.
 	int64_t get_final_granule_pos() const;
 
-	Ref<OGGPacketSequencePlayback> instance_playback();
+	Ref<OGGPacketSequencePlayback> instantiate_playback();
 
 	OGGPacketSequence() {}
 	virtual ~OGGPacketSequence() {}
diff --git a/modules/theora/video_stream_theora.h b/modules/theora/video_stream_theora.h
index 8940ed6aff..dd69bf066a 100644
--- a/modules/theora/video_stream_theora.h
+++ b/modules/theora/video_stream_theora.h
@@ -170,7 +170,7 @@ protected:
 	static void _bind_methods();
 
 public:
-	Ref<VideoStreamPlayback> instance_playback() override {
+	Ref<VideoStreamPlayback> instantiate_playback() override {
 		Ref<VideoStreamPlaybackTheora> pb = memnew(VideoStreamPlaybackTheora);
 		pb->set_audio_track(audio_track);
 		pb->set_file(file);
diff --git a/modules/vorbis/audio_stream_ogg_vorbis.cpp b/modules/vorbis/audio_stream_ogg_vorbis.cpp
index 89a6b03ff8..76f7317daa 100644
--- a/modules/vorbis/audio_stream_ogg_vorbis.cpp
+++ b/modules/vorbis/audio_stream_ogg_vorbis.cpp
@@ -43,28 +43,93 @@ int AudioStreamPlaybackOGGVorbis::_mix_internal(AudioFrame *p_buffer, int p_fram
 
 	int todo = p_frames;
 
-	int start_buffer = 0;
+	int beat_length_frames = -1;
+	bool beat_loop = vorbis_stream->has_loop();
+	if (beat_loop && vorbis_stream->get_bpm() > 0 && vorbis_stream->get_beat_count() > 0) {
+		beat_length_frames = vorbis_stream->get_beat_count() * vorbis_data->get_sampling_rate() * 60 / vorbis_stream->get_bpm();
+	}
 
 	while (todo > 0 && active) {
 		AudioFrame *buffer = p_buffer;
-		if (start_buffer > 0) {
-			buffer = buffer + start_buffer;
+		buffer += p_frames - todo;
+
+		int to_mix = todo;
+		if (beat_length_frames >= 0 && (beat_length_frames - (int)frames_mixed) < to_mix) {
+			to_mix = MAX(0, beat_length_frames - (int)frames_mixed);
 		}
-		int mixed = _mix_frames_vorbis(buffer, todo);
+
+		int mixed = _mix_frames_vorbis(buffer, to_mix);
 		ERR_FAIL_COND_V(mixed < 0, 0);
 		todo -= mixed;
 		frames_mixed += mixed;
-		start_buffer += mixed;
+
+		if (loop_fade_remaining < FADE_SIZE) {
+			int to_fade = loop_fade_remaining + MIN(FADE_SIZE - loop_fade_remaining, mixed);
+			for (int i = loop_fade_remaining; i < to_fade; i++) {
+				buffer[i - loop_fade_remaining] += loop_fade[i] * (float(FADE_SIZE - i) / float(FADE_SIZE));
+			}
+			loop_fade_remaining = to_fade;
+		}
+
+		if (beat_length_frames >= 0) {
+			/**
+			 * Length determined by beat length
+			 * This code is commented out because, in practice, it is prefered that the fade
+			 * is done by the transitioner and this stream just goes on until it ends while fading out.
+			 *
+			 * End fade implementation is left here for reference in case at some point this feature
+			 * is desired.
+
+			if (!beat_loop && (int)frames_mixed > beat_length_frames - FADE_SIZE) {
+				print_line("beat length fade/after mix?");
+				//No loop, just fade and finish
+				for (int i = 0; i < mixed; i++) {
+					int idx = frames_mixed + i - mixed;
+					buffer[i] *= 1.0 - float(MAX(0, (idx - (beat_length_frames - FADE_SIZE)))) / float(FADE_SIZE);
+				}
+				if ((int)frames_mixed == beat_length_frames) {
+					for (int i = p_frames - todo; i < p_frames; i++) {
+						p_buffer[i] = AudioFrame(0, 0);
+					}
+					active = false;
+					break;
+				}
+			} else
+			**/
+
+			if (beat_loop && beat_length_frames <= (int)frames_mixed) {
+				// End of file when doing beat-based looping. <= used instead of == because importer editing
+				if (!have_packets_left && !have_samples_left) {
+					//Nothing remaining, so do nothing.
+					loop_fade_remaining = FADE_SIZE;
+				} else {
+					// Add some loop fade;
+					int faded_mix = _mix_frames_vorbis(loop_fade, FADE_SIZE);
+
+					for (int i = faded_mix; i < FADE_SIZE; i++) {
+						// In case lesss was mixed, pad with zeros
+						loop_fade[i] = AudioFrame(0, 0);
+					}
+					loop_fade_remaining = 0;
+				}
+
+				seek(vorbis_stream->loop_offset);
+				loops++;
+				// We still have buffer to fill, start from this element in the next iteration.
+				continue;
+			}
+		}
+
 		if (!have_packets_left && !have_samples_left) {
-			//end of file!
+			// Actual end of file!
 			bool is_not_empty = mixed > 0 || vorbis_stream->get_length() > 0;
 			if (vorbis_stream->loop && is_not_empty) {
 				//loop
 
 				seek(vorbis_stream->loop_offset);
 				loops++;
-				// we still have buffer to fill, start from this element in the next iteration.
-				start_buffer = p_frames - todo;
+				// We still have buffer to fill, start from this element in the next iteration.
+
 			} else {
 				for (int i = p_frames - todo; i < p_frames; i++) {
 					p_buffer[i] = AudioFrame(0, 0);
@@ -130,7 +195,7 @@ bool AudioStreamPlaybackOGGVorbis::_alloc_vorbis() {
 	comment_is_allocated = true;
 
 	ERR_FAIL_COND_V(vorbis_data.is_null(), false);
-	vorbis_data_playback = vorbis_data->instance_playback();
+	vorbis_data_playback = vorbis_data->instantiate_playback();
 
 	ogg_packet *packet;
 	int err;
@@ -160,6 +225,7 @@ bool AudioStreamPlaybackOGGVorbis::_alloc_vorbis() {
 
 void AudioStreamPlaybackOGGVorbis::start(float p_from_pos) {
 	ERR_FAIL_COND(!ready);
+	loop_fade_remaining = FADE_SIZE;
 	active = true;
 	seek(p_from_pos);
 	loops = 0;
@@ -182,6 +248,10 @@ float AudioStreamPlaybackOGGVorbis::get_playback_position() const {
 	return float(frames_mixed) / vorbis_data->get_sampling_rate();
 }
 
+void AudioStreamPlaybackOGGVorbis::tag_used_streams() {
+	vorbis_stream->tag_used(get_playback_position());
+}
+
 void AudioStreamPlaybackOGGVorbis::seek(float p_time) {
 	ERR_FAIL_COND(!ready);
 	ERR_FAIL_COND(vorbis_stream.is_null());
@@ -315,7 +385,7 @@ AudioStreamPlaybackOGGVorbis::~AudioStreamPlaybackOGGVorbis() {
 	}
 }
 
-Ref<AudioStreamPlayback> AudioStreamOGGVorbis::instance_playback() {
+Ref<AudioStreamPlayback> AudioStreamOGGVorbis::instantiate_playback() {
 	Ref<AudioStreamPlaybackOGGVorbis> ovs;
 
 	ERR_FAIL_COND_V(packet_sequence.is_null(), nullptr);
@@ -347,7 +417,7 @@ void AudioStreamOGGVorbis::maybe_update_info() {
 	vorbis_info_init(&info);
 	vorbis_comment_init(&comment);
 
-	Ref<OGGPacketSequencePlayback> packet_sequence_playback = packet_sequence->instance_playback();
+	Ref<OGGPacketSequencePlayback> packet_sequence_playback = packet_sequence->instantiate_playback();
 
 	for (int i = 0; i < 3; i++) {
 		ogg_packet *packet;
@@ -405,6 +475,36 @@ float AudioStreamOGGVorbis::get_length() const {
 	return packet_sequence->get_length();
 }
 
+void AudioStreamOGGVorbis::set_bpm(double p_bpm) {
+	ERR_FAIL_COND(p_bpm < 0);
+	bpm = p_bpm;
+	emit_changed();
+}
+
+double AudioStreamOGGVorbis::get_bpm() const {
+	return bpm;
+}
+
+void AudioStreamOGGVorbis::set_beat_count(int p_beat_count) {
+	ERR_FAIL_COND(p_beat_count < 0);
+	beat_count = p_beat_count;
+	emit_changed();
+}
+
+int AudioStreamOGGVorbis::get_beat_count() const {
+	return beat_count;
+}
+
+void AudioStreamOGGVorbis::set_bar_beats(int p_bar_beats) {
+	ERR_FAIL_COND(p_bar_beats < 2);
+	bar_beats = p_bar_beats;
+	emit_changed();
+}
+
+int AudioStreamOGGVorbis::get_bar_beats() const {
+	return bar_beats;
+}
+
 bool AudioStreamOGGVorbis::is_monophonic() const {
 	return false;
 }
@@ -419,7 +519,19 @@ void AudioStreamOGGVorbis::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("set_loop_offset", "seconds"), &AudioStreamOGGVorbis::set_loop_offset);
 	ClassDB::bind_method(D_METHOD("get_loop_offset"), &AudioStreamOGGVorbis::get_loop_offset);
 
+	ClassDB::bind_method(D_METHOD("set_bpm", "bpm"), &AudioStreamOGGVorbis::set_bpm);
+	ClassDB::bind_method(D_METHOD("get_bpm"), &AudioStreamOGGVorbis::get_bpm);
+
+	ClassDB::bind_method(D_METHOD("set_beat_count", "count"), &AudioStreamOGGVorbis::set_beat_count);
+	ClassDB::bind_method(D_METHOD("get_beat_count"), &AudioStreamOGGVorbis::get_beat_count);
+
+	ClassDB::bind_method(D_METHOD("set_bar_beats", "count"), &AudioStreamOGGVorbis::set_bar_beats);
+	ClassDB::bind_method(D_METHOD("get_bar_beats"), &AudioStreamOGGVorbis::get_bar_beats);
+
 	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "packet_sequence", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_NO_EDITOR), "set_packet_sequence", "get_packet_sequence");
+	ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "bpm", PROPERTY_HINT_RANGE, "0,400,0.01,or_greater"), "set_bpm", "get_bpm");
+	ADD_PROPERTY(PropertyInfo(Variant::INT, "beat_count", PROPERTY_HINT_RANGE, "0,512,1,or_greater"), "set_beat_count", "get_beat_count");
+	ADD_PROPERTY(PropertyInfo(Variant::INT, "bar_beats", PROPERTY_HINT_RANGE, "2,32,1,or_greater"), "set_bar_beats", "get_bar_beats");
 	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "loop"), "set_loop", "has_loop");
 	ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "loop_offset"), "set_loop_offset", "get_loop_offset");
 }
diff --git a/modules/vorbis/audio_stream_ogg_vorbis.h b/modules/vorbis/audio_stream_ogg_vorbis.h
index b09ef9ff5d..22c2eb4d73 100644
--- a/modules/vorbis/audio_stream_ogg_vorbis.h
+++ b/modules/vorbis/audio_stream_ogg_vorbis.h
@@ -45,6 +45,12 @@ class AudioStreamPlaybackOGGVorbis : public AudioStreamPlaybackResampled {
 	bool active = false;
 	int loops = 0;
 
+	enum {
+		FADE_SIZE = 256
+	};
+	AudioFrame loop_fade[FADE_SIZE];
+	int loop_fade_remaining = FADE_SIZE;
+
 	vorbis_info info;
 	vorbis_comment comment;
 	vorbis_dsp_state dsp_state;
@@ -66,6 +72,7 @@ class AudioStreamPlaybackOGGVorbis : public AudioStreamPlaybackResampled {
 	Ref<OGGPacketSequencePlayback> vorbis_data_playback;
 	Ref<AudioStreamOGGVorbis> vorbis_stream;
 
+	int _mix_frames(AudioFrame *p_buffer, int p_frames);
 	int _mix_frames_vorbis(AudioFrame *p_buffer, int p_frames);
 
 	// Allocates vorbis data structures. Returns true upon success, false on failure.
@@ -85,6 +92,8 @@ public:
 	virtual float get_playback_position() const override;
 	virtual void seek(float p_time) override;
 
+	virtual void tag_used_streams() override;
+
 	AudioStreamPlaybackOGGVorbis() {}
 	~AudioStreamPlaybackOGGVorbis();
 };
@@ -107,17 +116,30 @@ class AudioStreamOGGVorbis : public AudioStream {
 
 	Ref<OGGPacketSequence> packet_sequence;
 
+	double bpm = 0;
+	int beat_count = 0;
+	int bar_beats = 4;
+
 protected:
 	static void _bind_methods();
 
 public:
 	void set_loop(bool p_enable);
-	bool has_loop() const;
+	virtual bool has_loop() const override;
 
 	void set_loop_offset(float p_seconds);
 	float get_loop_offset() const;
 
-	virtual Ref<AudioStreamPlayback> instance_playback() override;
+	void set_bpm(double p_bpm);
+	virtual double get_bpm() const override;
+
+	void set_beat_count(int p_beat_count);
+	virtual int get_beat_count() const override;
+
+	void set_bar_beats(int p_bar_beats);
+	virtual int get_bar_beats() const override;
+
+	virtual Ref<AudioStreamPlayback> instantiate_playback() override;
 	virtual String get_stream_name() const override;
 
 	void set_packet_sequence(Ref<OGGPacketSequence> p_packet_sequence);
diff --git a/modules/vorbis/doc_classes/AudioStreamOGGVorbis.xml b/modules/vorbis/doc_classes/AudioStreamOGGVorbis.xml
index 2f210a6cb4..f87296dcd8 100644
--- a/modules/vorbis/doc_classes/AudioStreamOGGVorbis.xml
+++ b/modules/vorbis/doc_classes/AudioStreamOGGVorbis.xml
@@ -7,6 +7,12 @@
 	<tutorials>
 	</tutorials>
 	<members>
+		<member name="bar_beats" type="int" setter="set_bar_beats" getter="get_bar_beats" default="4">
+		</member>
+		<member name="beat_count" type="int" setter="set_beat_count" getter="get_beat_count" default="0">
+		</member>
+		<member name="bpm" type="float" setter="set_bpm" getter="get_bpm" default="0.0">
+		</member>
 		<member name="loop" type="bool" setter="set_loop" getter="has_loop" default="false">
 			If [code]true[/code], the stream will automatically loop when it reaches the end.
 		</member>
diff --git a/modules/vorbis/resource_importer_ogg_vorbis.cpp b/modules/vorbis/resource_importer_ogg_vorbis.cpp
index 7ee6446313..9461d531fd 100644
--- a/modules/vorbis/resource_importer_ogg_vorbis.cpp
+++ b/modules/vorbis/resource_importer_ogg_vorbis.cpp
@@ -30,13 +30,16 @@
 
 #include "resource_importer_ogg_vorbis.h"
 
-#include "audio_stream_ogg_vorbis.h"
 #include "core/io/file_access.h"
 #include "core/io/resource_saver.h"
 #include "scene/resources/texture.h"
 #include "thirdparty/libogg/ogg/ogg.h"
 #include "thirdparty/libvorbis/vorbis/codec.h"
 
+#ifdef TOOLS_ENABLED
+#include "editor/import/audio_stream_import_settings.h"
+#endif
+
 String ResourceImporterOGGVorbis::get_importer_name() const {
 	return "oggvorbisstr";
 }
@@ -72,14 +75,14 @@ String ResourceImporterOGGVorbis::get_preset_name(int p_idx) const {
 void ResourceImporterOGGVorbis::get_import_options(const String &p_path, List<ImportOption> *r_options, int p_preset) const {
 	r_options->push_back(ImportOption(PropertyInfo(Variant::BOOL, "loop"), true));
 	r_options->push_back(ImportOption(PropertyInfo(Variant::FLOAT, "loop_offset"), 0));
+	r_options->push_back(ImportOption(PropertyInfo(Variant::FLOAT, "bpm", PROPERTY_HINT_RANGE, "0,400,0.01,or_greater"), 0));
+	r_options->push_back(ImportOption(PropertyInfo(Variant::INT, "beat_count", PROPERTY_HINT_RANGE, "0,512,or_greater"), 0));
+	r_options->push_back(ImportOption(PropertyInfo(Variant::INT, "bar_beats", PROPERTY_HINT_RANGE, "2,32,or_greater"), 4));
 }
 
-Error ResourceImporterOGGVorbis::import(const String &p_source_file, const String &p_save_path, const HashMap<StringName, Variant> &p_options, List<String> *r_platform_variants, List<String> *r_gen_files, Variant *r_metadata) {
-	bool loop = p_options["loop"];
-	float loop_offset = p_options["loop_offset"];
-
-	Ref<FileAccess> f = FileAccess::open(p_source_file, FileAccess::READ);
-	ERR_FAIL_COND_V_MSG(f.is_null(), ERR_CANT_OPEN, "Cannot open file '" + p_source_file + "'.");
+Ref<AudioStreamOGGVorbis> ResourceImporterOGGVorbis::import_ogg_vorbis(const String &p_path) {
+	Ref<FileAccess> f = FileAccess::open(p_path, FileAccess::READ);
+	ERR_FAIL_COND_V_MSG(f.is_null(), Ref<AudioStreamOGGVorbis>(), "Cannot open file '" + p_path + "'.");
 
 	uint64_t len = f->get_length();
 
@@ -107,16 +110,16 @@ Error ResourceImporterOGGVorbis::import(const String &p_source_file, const Strin
 	size_t packet_count = 0;
 	bool done = false;
 	while (!done) {
-		ERR_FAIL_COND_V_MSG((err = ogg_sync_check(&sync_state)), Error::ERR_INVALID_DATA, "Ogg sync error " + itos(err));
+		ERR_FAIL_COND_V_MSG((err = ogg_sync_check(&sync_state)), Ref<AudioStreamOGGVorbis>(), "Ogg sync error " + itos(err));
 		while (ogg_sync_pageout(&sync_state, &page) != 1) {
 			if (cursor >= len) {
 				done = true;
 				break;
 			}
-			ERR_FAIL_COND_V_MSG((err = ogg_sync_check(&sync_state)), Error::ERR_INVALID_DATA, "Ogg sync error " + itos(err));
+			ERR_FAIL_COND_V_MSG((err = ogg_sync_check(&sync_state)), Ref<AudioStreamOGGVorbis>(), "Ogg sync error " + itos(err));
 			char *sync_buf = ogg_sync_buffer(&sync_state, OGG_SYNC_BUFFER_SIZE);
-			ERR_FAIL_COND_V_MSG((err = ogg_sync_check(&sync_state)), Error::ERR_INVALID_DATA, "Ogg sync error " + itos(err));
-			ERR_FAIL_COND_V(cursor > len, Error::ERR_INVALID_DATA);
+			ERR_FAIL_COND_V_MSG((err = ogg_sync_check(&sync_state)), Ref<AudioStreamOGGVorbis>(), "Ogg sync error " + itos(err));
+			ERR_FAIL_COND_V(cursor > len, Ref<AudioStreamOGGVorbis>());
 			size_t copy_size = len - cursor;
 			if (copy_size > OGG_SYNC_BUFFER_SIZE) {
 				copy_size = OGG_SYNC_BUFFER_SIZE;
@@ -124,22 +127,22 @@ Error ResourceImporterOGGVorbis::import(const String &p_source_file, const Strin
 			memcpy(sync_buf, &file_data[cursor], copy_size);
 			ogg_sync_wrote(&sync_state, copy_size);
 			cursor += copy_size;
-			ERR_FAIL_COND_V_MSG((err = ogg_sync_check(&sync_state)), Error::ERR_INVALID_DATA, "Ogg sync error " + itos(err));
+			ERR_FAIL_COND_V_MSG((err = ogg_sync_check(&sync_state)), Ref<AudioStreamOGGVorbis>(), "Ogg sync error " + itos(err));
 		}
 		if (done) {
 			break;
 		}
-		ERR_FAIL_COND_V_MSG((err = ogg_sync_check(&sync_state)), Error::ERR_INVALID_DATA, "Ogg sync error " + itos(err));
+		ERR_FAIL_COND_V_MSG((err = ogg_sync_check(&sync_state)), Ref<AudioStreamOGGVorbis>(), "Ogg sync error " + itos(err));
 
 		// Have a page now.
 		if (!initialized_stream) {
 			if (ogg_stream_init(&stream_state, ogg_page_serialno(&page))) {
-				ERR_FAIL_V_MSG(Error::ERR_OUT_OF_MEMORY, "Failed allocating memory for OGG Vorbis stream.");
+				ERR_FAIL_V_MSG(Ref<AudioStreamOGGVorbis>(), "Failed allocating memory for OGG Vorbis stream.");
 			}
 			initialized_stream = true;
 		}
 		ogg_stream_pagein(&stream_state, &page);
-		ERR_FAIL_COND_V_MSG((err = ogg_stream_check(&stream_state)), Error::ERR_INVALID_DATA, "Ogg stream error " + itos(err));
+		ERR_FAIL_COND_V_MSG((err = ogg_stream_check(&stream_state)), Ref<AudioStreamOGGVorbis>(), "Ogg stream error " + itos(err));
 		int desync_iters = 0;
 
 		Vector<Vector<uint8_t>> packet_data;
@@ -150,7 +153,7 @@ Error ResourceImporterOGGVorbis::import(const String &p_source_file, const Strin
 			if (err == -1) {
 				// According to the docs this is usually recoverable, but don't sit here spinning forever.
 				desync_iters++;
-				ERR_FAIL_COND_V_MSG(desync_iters > 100, Error::ERR_INVALID_DATA, "Packet sync issue during ogg import");
+				ERR_FAIL_COND_V_MSG(desync_iters > 100, Ref<AudioStreamOGGVorbis>(), "Packet sync issue during ogg import");
 				continue;
 			} else if (err == 0) {
 				// Not enough data to fully reconstruct a packet. Go on to the next page.
@@ -183,12 +186,45 @@ Error ResourceImporterOGGVorbis::import(const String &p_source_file, const Strin
 	ogg_sync_clear(&sync_state);
 
 	if (ogg_packet_sequence->get_packet_granule_positions().is_empty()) {
-		ERR_FAIL_V_MSG(Error::ERR_FILE_CORRUPT, "OGG Vorbis decoding failed. Check that your data is a valid OGG Vorbis audio stream.");
+		ERR_FAIL_V_MSG(Ref<AudioStreamOGGVorbis>(), "OGG Vorbis decoding failed. Check that your data is a valid OGG Vorbis audio stream.");
 	}
 
 	ogg_vorbis_stream->set_packet_sequence(ogg_packet_sequence);
+
+	return ogg_vorbis_stream;
+}
+
+#ifdef TOOLS_ENABLED
+
+bool ResourceImporterOGGVorbis::has_advanced_options() const {
+	return true;
+}
+
+void ResourceImporterOGGVorbis::show_advanced_options(const String &p_path) {
+	Ref<AudioStreamOGGVorbis> ogg_stream = import_ogg_vorbis(p_path);
+	if (ogg_stream.is_valid()) {
+		AudioStreamImportSettings::get_singleton()->edit(p_path, "oggvorbisstr", ogg_stream);
+	}
+}
+#endif
+
+Error ResourceImporterOGGVorbis::import(const String &p_source_file, const String &p_save_path, const HashMap<StringName, Variant> &p_options, List<String> *r_platform_variants, List<String> *r_gen_files, Variant *r_metadata) {
+	bool loop = p_options["loop"];
+	float loop_offset = p_options["loop_offset"];
+	double bpm = p_options["bpm"];
+	int beat_count = p_options["beat_count"];
+	int bar_beats = p_options["bar_beats"];
+
+	Ref<AudioStreamOGGVorbis> ogg_vorbis_stream = import_ogg_vorbis(p_source_file);
+	if (ogg_vorbis_stream.is_null()) {
+		return ERR_CANT_OPEN;
+	}
+
 	ogg_vorbis_stream->set_loop(loop);
 	ogg_vorbis_stream->set_loop_offset(loop_offset);
+	ogg_vorbis_stream->set_bpm(bpm);
+	ogg_vorbis_stream->set_beat_count(beat_count);
+	ogg_vorbis_stream->set_bar_beats(bar_beats);
 
 	return ResourceSaver::save(p_save_path + ".oggvorbisstr", ogg_vorbis_stream);
 }
diff --git a/modules/vorbis/resource_importer_ogg_vorbis.h b/modules/vorbis/resource_importer_ogg_vorbis.h
index 3b4a68a1fd..e6e98a29c1 100644
--- a/modules/vorbis/resource_importer_ogg_vorbis.h
+++ b/modules/vorbis/resource_importer_ogg_vorbis.h
@@ -31,6 +31,7 @@
 #ifndef RESOURCE_IMPORTER_OGG_VORBIS_H
 #define RESOURCE_IMPORTER_OGG_VORBIS_H
 
+#include "audio_stream_ogg_vorbis.h"
 #include "core/io/resource_importer.h"
 
 class ResourceImporterOGGVorbis : public ResourceImporter {
@@ -43,7 +44,13 @@ class ResourceImporterOGGVorbis : public ResourceImporter {
 private:
 	// virtual int get_samples_in_packet(Vector<uint8_t> p_packet) = 0;
 
+	static Ref<AudioStreamOGGVorbis> import_ogg_vorbis(const String &p_path);
+
 public:
+#ifdef TOOLS_ENABLED
+	virtual bool has_advanced_options() const override;
+	virtual void show_advanced_options(const String &p_path) override;
+#endif
 	virtual void get_recognized_extensions(List<String> *p_extensions) const override;
 	virtual String get_save_extension() const override;
 	virtual String get_resource_type() const override;