[FFmpeg-devel] [Brainstorming] sound reproduction with a 3 voice soundchip

[Tobias Bindhammer]

Hi Fran?ois,

> FWIW I posted this on irc://ircnet/oric to some people doing music stuff on 8bit machines, here is what he said:
> 
> <twilighte_> ok, i am reminded of a similar technique dbug linked me to many years ago, something like ver.. something
> memory not so good
> its the idea of using the oscillators directly as pulse width generators, the idea that lower frequencies represent wider pulse widths and higher frequencies shorter pulse widths
> in this way a pulse code modulation could be reproduced by directly feeding a pulse code modulated waveform into the oscilator frequency registers
> It was theorised doing this could also raise the oppertunity to reproduce 3 channels samples to much greater accuracy than 4 bit samples
> its a hack though since adjusting the oscillator frequency does not reset the waveform cycle. So sound reproduction quality may be lost
> on the ay anyway. i don't know if the SID behaves in the same way
> i also don't know if any time could be saved in doing it this way (which is the aim of the original post)

Thanks for your efforts! I think this sounds like this:
http://noname.c64.org/csdb/release/?id=72678&show=notes#notes
However this also works on playback of sampled data and consumes a lot
of cpu, as well as uses up a lot of bandwidth and memory. In comparision
my vague thoughts would need like a few hundred bytes per second, and
about as much cycles.

Another example would be this from 2010:
http://noname.c64.org/csdb/release/?id=94453

i experienced both live when they were first showed at x2008 and x2010
in netherlands. However the sparce effects and lagging text-gui shows,
that cpu is used heavily.

Toby

-- 
Dipl. Ing. Tobias Bindhammer
Institut f?r Verteilte Systeme
Oberer Eselsberg          Phone: + 49 731/502-4235
Universit?t Ulm           Fax  : + 49 731/502-4142
D-89069 Ulm               mailto:tobias.bindhammer at uni-ulm.de
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