4 ms·

> Not that the C64 SID chip was even remotely intended to be able to play sampled audio in the first place! I don't recall how SAM did it, but sample playing o

> Not that the C64 SID chip was even remotely intended to be able to play sampled audio in the first place! I don't recall how SAM did it, but sample playing on the C64 SID chip was indeed a nice trick — it was actually done by modulating the main output volume, which made a slight click when changing. Eventually this got used by some of the C64 musicians / music player libs, so one could play a channel of samples as well as the three regular synth channels on the SID. IIRC, Outrun used this particularly well in its title screen and/or loading music, having some vocal samples "O-O-Outrun!" (and skidding sound effects) as well a sampled drums. Annoyingly, IIRC, some revisions of the SID chip behaved slightly differently, and had louder or softer sample playback when this hack was used. But still: clever stuff.

weinzierl 4y ago
... and main output volume had only 16 levels so the samples were 4 bit quantized. It is a wonder that we could get understandable vocal samples with this hack at all. I distinctly remember "Goal!" from Peter Shilton's Fottball and "Accolade presents" from Test Drive [1]. In the examples one can hear the amount of quantization noise that low bit depth caused. [1] https://m.youtube.com/watch?v=L1u-WydiiCI https://m.youtube.com/watch?v=L1u-WydiiCI
- vardump 4y ago
  You can actually get about 6-7 bits resolution out of same SID volume register. 4 bits from the volume register, channel 3 disable and 3 filter bits. Requires some setup to get SID in a particular state first. For details, see: https://livet.se/mahoney/c64-files/Musik_RunStop_Technical_Details_by_Pex_Mahoney_Tufvesson_v2.pdf https://livet.se/mahoney/c64-files/Musik_RunStop_Technical_D...
  - weinzierl 4y ago
    I was just wondering tonight, while lying awake, if you could get more depth by either using the other voices (probably not) or the filter. Now this paper and the demo are so cool, really made my day.
    - vardump 4y ago
      > using the other voices Yeah, you can do that as well, well kinda, but it's harder, provides a lower maximum frequency and wastes more CPU cycles. See: https://csdb.dk/release/?id=72678&show=notes https://csdb.dk/release/?id=72678&show=notes There have also been efforts to do "sampled" sound synthesis with C64's 3 voices, speech, etc. I don't remember any links about that, unfortunately.

weinzierl 4y ago

... and main output volume had only 16 levels so the samples were 4 bit quantized. It is a wonder that we could get understandable vocal samples with this hack at all. I distinctly remember "Goal!" from Peter Shilton's Fottball and "Accolade presents" from Test Drive [1]. In the examples one can hear the amount of quantization noise that low bit depth caused. [1] https://m.youtube.com/watch?v=L1u-WydiiCI https://m.youtube.com/watch?v=L1u-WydiiCI

vardump 4y ago
You can actually get about 6-7 bits resolution out of same SID volume register. 4 bits from the volume register, channel 3 disable and 3 filter bits. Requires some setup to get SID in a particular state first. For details, see: https://livet.se/mahoney/c64-files/Musik_RunStop_Technical_Details_by_Pex_Mahoney_Tufvesson_v2.pdf https://livet.se/mahoney/c64-files/Musik_RunStop_Technical_D...
- weinzierl 4y ago
  I was just wondering tonight, while lying awake, if you could get more depth by either using the other voices (probably not) or the filter. Now this paper and the demo are so cool, really made my day.
  - vardump 4y ago
    > using the other voices Yeah, you can do that as well, well kinda, but it's harder, provides a lower maximum frequency and wastes more CPU cycles. See: https://csdb.dk/release/?id=72678&show=notes https://csdb.dk/release/?id=72678&show=notes There have also been efforts to do "sampled" sound synthesis with C64's 3 voices, speech, etc. I don't remember any links about that, unfortunately.