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MRT
Account closed
Registered: Sep 2005
Posts: 149 |
HowTo: Digi Samples on the SID
Im' thinking of writing a sample-play routine for a demo, but as it seems I'm not sure where to start.
Can somebody explain to me the basics of playing samples on a SID? Things I'm not sure about are:
1. How does one set the volume for one channel? Using the Sustain of the envelope and setting the A, D and R to zero?
2. What kind of wave (Triangle, Block) do I use and why?
3. Do I need a 8x system to play a 400Hz sample? (50 Hz * 8x)
And I prolly have a lot more questions, but I'll ask them when I understand a little more of the basics. :-)
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chatGPZ
Registered: Dec 2001
Posts: 11386 |
ah ok yes :) what i'm referring to is that if you play a square wave using volume register, the higher the frequency is, the less the actual output will actually be square :) there will be lots of distortion introduced due to the capacitors charging and discharging....effectivly defeating most techniques of removing distortion :=P (and ofcourse, anything else played on the normal sid voices will have its influence here aswell, and finally ruin every effort of compensating the effect by preprocessing) |
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tlr
Registered: Sep 2003
Posts: 1790 |
Quote: ah ok yes :) what i'm referring to is that if you play a square wave using volume register, the higher the frequency is, the less the actual output will actually be square :) there will be lots of distortion introduced due to the capacitors charging and discharging....effectivly defeating most techniques of removing distortion :=P (and ofcourse, anything else played on the normal sid voices will have its influence here aswell, and finally ruin every effort of compensating the effect by preprocessing)
Do you mean like a regular filter with differing cutoff frequency due to capacitor tolerances, or do you mean an asymmetrical effect due to a different output impedance when driving or sinking the output? |
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chatGPZ
Registered: Dec 2001
Posts: 11386 |
the latter... its somewhat as if a lowpass filter would be applied to the final output...just more complex than with normal filters :=P you get a quite funny signal depending on whats played on the sid voices at the same time. |
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tlr
Registered: Sep 2003
Posts: 1790 |
Quote: the latter... its somewhat as if a lowpass filter would be applied to the final output...just more complex than with normal filters :=P you get a quite funny signal depending on whats played on the sid voices at the same time.
Ok, check! :)
Harder to compensate for that. Maybe for samples only, but the assymetrical filtering effect could well introduce so much distortion that it masks the other effects. |
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