I'm trying to build a programmable sound generator in GD Script--Sine, Square, and Triangle Waves, that kind of thing. My goal is basically to impliment something like BFXR in Godot. I've worked on making ADSR envelopes, tremolo, vibrato, slides, random volume shimmer, and random pitch jitter. They're all "working," but they're producing unexpected noise.
Pure sine waves are okay, for instance, but the ADSR envelop produces a scraping noise when my volumes over 50%. I'm not an expert on DSP stuff, so it's hard to diagnose whether these issues or me, or Godot, which I understand still has issues with Windows drivers. Here's my basic code:
func _ready():
$Player.stream.mix_rate = sample_rate
playback = $Player.get_stream_playback()
generate_wave(0.0)
$Player.play()
func _process(delta):
var increment = pitch / sample_rate
var to_fill = min(playback.get_frames_available(), sample_rate * delta)
while to_fill > 0:
var sample = Vector2.ONE * sin(phase * TAU)
phase += increment
if phase >= 1.0:
volume_update(1 / pitch) #Update's Volume Adjustment according to master volume * ADSR envelope
phase = fmod(phase, 1.0)
sample *= volume_adjustment
playback.push_frame(sample)
to_fill -= 1
I could also provide the volume_update function for the ADSR stuff, but this is the gist of it. Any obvious ideas why this would cause noise?
