Sample Playback

[ascarrar]

Does anyone know if Pulse Density Modulation sample playback is possible with the SID chip? Seems that setting the oscillator at some high frequency value and using the pulse width to playback samples encoded in PDM format would work.

[m00dawg]

According to Wikipedia, you can using various methods. I don't think you could easily do that with an MBSID without some pretty heavy modifications though. I found this technique rather interesting (and new):

"At the X'2008 demo party, a completely new method of playing digitized samples was unveiled. The method allows for an unprecedented four (software-mixed) channels of 8-bit samples with optional filtering on top of all samples, as well as two ordinary SID sound channels.[2][3] The method works by resetting the oscillator using the waveform generator test bit, quickly ramping up the new waveform with the Triangle waveform selected, and then disabling all waveforms, resulting in the DAC continuing to output the last value---which is the desired sample. This continues for as long as two scanlines, which is ample time for glitch-free, arbitrary sample output. It is however more CPU-intensive than the 4-bit volume register DAC trick described above. Because the filtering in a SID chip is applied after the waveform generators, samples produced this way can be filtered normally."