Heck yeah... I was just thinking LPCM at a multiple of the hsync rate or something for 'easy', but ADPCM could be nice-- not a lot of cycles as I recall. I always thought 3 bit ADPCM sounded a little too "gravel-ly". 4 bit was good. Of course 4bit ADPCM only gives 2:1 ove 8 bit LPCM which would be no CPU impact to speak of... Just pick something that Goldwave or other common/cheap/free editors can grok. (Dialogic had an ADPCM, OKI had their own, etc.)uze6666 wrote:[Yeah, and for myself, I really don't like the sound of the noise channel, since the mixing frequency is too low. So it's pretty hard to make effects sound good, specially for music (like hi-hats, snares, etc) . So with samples, the real issue is space...unless we accept fixed samples (no pitch control). I could then implement a simple ADPCM decoder and we could easily get 3:1 to 4:1 compression. Enough to store very interesting samples I think.
Any idea how many bits of resolution you're really getting out of the PWM output? I also suspect a lot of low-cost filters will start to roll off at ~10KHz to try to keep Hsync noise out of the audio channel. (...and a steeper filter is rather a lot of parts-- I have that one on the baseboards, but I admit I haven't tried populating it. Keep adding parts to my Digikey order!)
-Clay