Unfortunately the triangle wave instruments (0 & 7) tend to pile up and clip quite easily when they are the same or related frequencies. i.e. when adding the channel outputs together, they exceed the maximum volume and need to be cropped. The cropping causes abrupt changes in the waveform and results in buzzy noises. Here are some examples from the start of pattern 6:
(they are supposed to all be triangle shapes but end up with those flat regions to stay within the int16 signal range of -32768..32767)
Some ways to avoid clipping:
- reduce volume a little on all channels
- turn off reverb -- this causes more peaks to be added together sometimes
- turn up dampening to make peaks a little shorter
- try varying instruments more (e.g. use a square wave based kick drum)
- avoid playing too many harmonically related notes (octaves, 4ths,5ths) at once
I don't know if any of these help you much though! I tried playing around with pattern 6, and it seems quite hard to reduce the clipping effect without changing the sound a lot (and without just aggressively reducing the volume of each channel).
PICO-8 does use a simple limiting function to reduce the effect of clipping, but I tried it just now, and it sounds /worse/ than hard clipping in this example. I'll have a look at coming up with a better soft clipping function for 0.2.6.
Couldd/Does Pico8 adjust the dampening based on the last 1-8 frames ?
@zep
Thank you for your detailed explanation!!
I changed the settings with your attention, and the cracking noises are gone in my environment.
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