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.

1 files changed, 24 insertions, 2 deletions

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);