> Nate: Doesnt modplay64 use PWM in one of its sid modes? Yes, it does. It achieves something like 33 kHz 8-bit stereo (with two SIDS) and I think somewhere close to 60 kHz in mono. Since the SID can only produce waves of around 4 kHz in 8 bits, I use two voices (on each SID). Any more than 4 kHz and the SID starts dropping the lower bits (because in an NTSC C64 the SID has a fixed "sample rate" of 1022727 Hz) at one bit per double in sample rate (e.g. 8kHz=7 bits). One voice produces the lower four bits of the sample data, with a Sustain setting that's roughly 1/16th the Sustain (in terms of amplitude) of the other voice, which produces the upper four bits. I get away with this Sustain business because the TEST bit, which is used to produce arbitrary pulse widths, does not reset the ADSR settings at all, only the Gate does, and I don't use that. The SID can maintain 4 bits of resolution using PWM, up to 64 kHz. Since I use two voices, and since each is good to 64 kHz, I affectively trick the SID into giving me a full 8 bits. 12 Bits might also be possible at very high sample rates, if you use all three voices and set the sustain levels accordingly. In theory, you could get 12 bits at 64 kHz with this method, if you can set the Sustain values correctly (I've never tried). Add in the low pass filter and quality improves beyond your existing settings, at the expense of overall volume and frequency response (which is why I chose to leave the filter disabled). > On Sat, 18 Nov 2000, Richard Atkinson wrote: > > > Has anyone ever used the SID's phase-accumulating oscillators together > > with a fast frequency register routine to generate phase-modulated sounds? I'd like to hear the results of using this method. -- _________________________________________ ___ _____ | . . : /XXZ| ___ | | _ _ _|_ _ _| _ _ : C64/C128- /X/ |ZZ/ | | |/ \ _| | / \ / | _| / ` : What's LH __ | | | |/ | | L-'| |/ || : *YOUR* \`\__ |__\ | | | |\_| |_.\_. \_|\_| \_. : hobby? \___| | `---------------------------------------------------' - This message was sent through the cbm-hackers mailing list. To unsubscribe: echo unsubscribe | mail email@example.com.
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