tutorials/audio/sync_with_audio

[giscus[bot]]

tutorials/audio/sync_with_audio

Introduction: In any application or game, sound and music playback will have a slight delay. For games, this delay is often so small that it is negligible. Sound effects will come out a few millise...

https://docs.godotengine.org/en/stable/tutorials/audio/sync_with_audio.html

[waso-mu]

Quick word of warning from a rhythm game developer:
AFAIK, you currently cannot accurately sync audio to gameplay, (only gameplay to audio as seen in this article). There's no way to schedule audio in advance, so you are limited to the user's framerate. For most games, not an issue. But if you are making music tools or a strict rhythm game, the delay is incredibly noticeable (esp on lower end devices) and can be unfair if not just offputting. You may be best off using a separate audio engine for your project if it requires accurate timed playback of rhythm.

[waso-mu]

I phrased the first sentence poorly, I mean you cannot accurately sync playback of audio to music, for example in the case of overlaying a hit-sound, metronome, or count-in.

[Calinou]

See proposal:

• Add an absolute time (DSP time) feature to play audio effects at specific intervals godot-proposals#1151

[waso-mu]

Here's a handy function code to convert seconds to crotchets (AKA beats/quarter notes):

# This dictionary stores each time the bpm changes in the song. It's in dictionary format since I wrote it to support custom levels stored in .json files. It does not support gradual BPM changes.
var bpm_changes:Array[Dictionary] = [ # Example value, sets the BPM to 120 at beat one and nothing else
    {
        "Crotchet":1.0, # The beat that the BPM changes
        "BPM":120,      # The BPM it changes to
    },
]

func seconds_to_crotchet(seconds:float) -> float:
	var remaining_seconds := seconds # I don't think this is necessary in gdscript, but just to be safe
	var last_bpm := 100.0 # arbitrary value in case no bpm is set on beat 1
	var last_crotchet := 1.0
	var total_crotchets := 1.0
	
	for change in bpm_changes:
		var full = remaining_seconds*last_bpm/60
		if full >= change["Crotchet"]:
			var diff = change["Crotchet"]-last_crotchet
			total_crotchets += diff
			remaining_seconds -= diff/last_bpm*60
			last_bpm = change["BPM"]
			last_crotchet = change["Crotchet"]
		else:
			break
	total_crotchets += remaining_seconds*last_bpm/60 + 1
	
	return total_crotchets