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MilkyTracker Support / Re: Help with SID sounds in Milkytracker
« on: December 05, 2016, 12:43:40 »
Old question, but I think a reasonable one.
Short answer: you can't.
But some of that stuff can be emulated to some degree. To learn how to do that, you have to learn how SID tunes are made. Start by learning GoatTracker. You will have to spend many hours studying how the SID chip works, and you'll have to spend many hours learning how the tracker software works, and how the playroutine works. All of these contribute to "the SID sound".
What "the SID sound" is, is highly subjective. For Atari ST folks, apparently pulse width modulation was the only thing needed, because they gave that effect the name "SID sound".
My guesses as to what someone might consider characteristic to the SID chip:
1. The oscillator waveforms themselves. Particularly the noise is quite unique.
2. Pulse width modulation, i.e. square waveform, but changing its width with a software envelope.
3. Player software idiosyncrasies
3.1. particularly arpeggio effects,
3.2. but also things like how drum sounds are typically done by playing short snippets of different waveforms from different pitches in tight sequence, "wave tables". And that a single SID oscillator/channel cannot play noise and pitched waveforms at the same time, it's either or. (Compared to, say, the AY/YM where the noise generator is a separate oscillator channel of its own) Well you can use combinations of waveforms, but it's more like a glitch, not very reliable, and I don't think anyone would associate the combined sounds as "the SID sound" in any way.
3.3 maybe the way the envelope generators need some time to reset, and why any previous sounding note has to be cut off (i.e. release the virtual synth keyboard key you're holding down), a couple of frames (something like 30-60 ms) before the next note starts, or otherwise you'll get a "mis-trigger". Someone might call this a deficiency of the SID chip, and in theory it might feel bad and cumbersome, but in practice I think it's actually musically good and adds a nice funky feeling to bass lines. I do the same thing when playing actual bass or programming bass lines in sequencers or trackers.
4. The hardware ADSR envelope shapes, which affect particularly the attacks of the sounds.
4.1 Also note that the SID chip doesn't really have "channel volume" in the same sense as ProTracker/MilkyTracker or the Amiga Paula chip or actually even the AY/YM/PSG chip (that's in Atari ST, Amstrad CPC, MSX etc.) The ADSR envelope's attack part always raises the oscillator's mixing level to maximum, unless it is stopped before reaching maximum, but there's no such thing as "attack LEVEL" or "channel LEVEL". You only have SUSTAIN LEVEL, but before reaching that the attack and decay parts of the envelope have been done
5. The analog filter. Not nearly all SID tunes use the filter at all, so how important it is really. And the filter sounds somewhat different in different SID versions.
6. Ring modulation. Particularly some Rob Hubbard tunes use the SID chip's ring modulation possibilities.
___
How could these be emulated?
1. The oscillator waveforms: these you can sample if you like
2. Pulse width modulation: not really possible in MilkyTracker, but you can sample a long PWM'ed lead sound. It should sound reasonably close.
3.1 Arpeggio effect: can be done with the 0xx arpeggio pattern effect
3.2 Wave tables... might be doable with tempo F01
Similar wave tables COULD be implemented as a new feature for the tracker and the playroutine, but the best you can do out of the box is to sample/rip actual SID drum sounds from SID tunes.
3.3 Cut notes slightly short: can be done with the ECx pattern command. For example if the tempo is F06, try using EC4 command.
4. The hardware envelopes: cannot really be done with XM envelopes, which are way too slow. You need to sample/rip sounds from SID tunes.
4.1 Do not use volume commands or instrument volume for "mixing" your channels. Do the balancing in the arrangement or inside the sample! That's the SID way. You can use instrument envelopes, if you can explain how the SID's hardware envelope could do that. But for example if you have a snare instrument sample, you must only play that sample with maximum volume.
5. Analog filter: cannot be done with existing features. You have to sample/rip SID tunes.
6. Ring modulation: cannot be done with MilkyTracker, so you have to sample/rip SID tunes.
Also: limit your expressions to things that can be done with the SID chip. Do not use stereo sound, because the SID is mono. Use max 3 channels. Only use samples from SID tunes or single waveforms, etc. Do not use volume commands.
Short answer: you can't.
But some of that stuff can be emulated to some degree. To learn how to do that, you have to learn how SID tunes are made. Start by learning GoatTracker. You will have to spend many hours studying how the SID chip works, and you'll have to spend many hours learning how the tracker software works, and how the playroutine works. All of these contribute to "the SID sound".
What "the SID sound" is, is highly subjective. For Atari ST folks, apparently pulse width modulation was the only thing needed, because they gave that effect the name "SID sound".
My guesses as to what someone might consider characteristic to the SID chip:
1. The oscillator waveforms themselves. Particularly the noise is quite unique.
2. Pulse width modulation, i.e. square waveform, but changing its width with a software envelope.
3. Player software idiosyncrasies
3.1. particularly arpeggio effects,
3.2. but also things like how drum sounds are typically done by playing short snippets of different waveforms from different pitches in tight sequence, "wave tables". And that a single SID oscillator/channel cannot play noise and pitched waveforms at the same time, it's either or. (Compared to, say, the AY/YM where the noise generator is a separate oscillator channel of its own) Well you can use combinations of waveforms, but it's more like a glitch, not very reliable, and I don't think anyone would associate the combined sounds as "the SID sound" in any way.
3.3 maybe the way the envelope generators need some time to reset, and why any previous sounding note has to be cut off (i.e. release the virtual synth keyboard key you're holding down), a couple of frames (something like 30-60 ms) before the next note starts, or otherwise you'll get a "mis-trigger". Someone might call this a deficiency of the SID chip, and in theory it might feel bad and cumbersome, but in practice I think it's actually musically good and adds a nice funky feeling to bass lines. I do the same thing when playing actual bass or programming bass lines in sequencers or trackers.
4. The hardware ADSR envelope shapes, which affect particularly the attacks of the sounds.
4.1 Also note that the SID chip doesn't really have "channel volume" in the same sense as ProTracker/MilkyTracker or the Amiga Paula chip or actually even the AY/YM/PSG chip (that's in Atari ST, Amstrad CPC, MSX etc.) The ADSR envelope's attack part always raises the oscillator's mixing level to maximum, unless it is stopped before reaching maximum, but there's no such thing as "attack LEVEL" or "channel LEVEL". You only have SUSTAIN LEVEL, but before reaching that the attack and decay parts of the envelope have been done
5. The analog filter. Not nearly all SID tunes use the filter at all, so how important it is really. And the filter sounds somewhat different in different SID versions.
6. Ring modulation. Particularly some Rob Hubbard tunes use the SID chip's ring modulation possibilities.
___
How could these be emulated?
1. The oscillator waveforms: these you can sample if you like
2. Pulse width modulation: not really possible in MilkyTracker, but you can sample a long PWM'ed lead sound. It should sound reasonably close.
3.1 Arpeggio effect: can be done with the 0xx arpeggio pattern effect
3.2 Wave tables... might be doable with tempo F01
Similar wave tables COULD be implemented as a new feature for the tracker and the playroutine, but the best you can do out of the box is to sample/rip actual SID drum sounds from SID tunes.3.3 Cut notes slightly short: can be done with the ECx pattern command. For example if the tempo is F06, try using EC4 command.
4. The hardware envelopes: cannot really be done with XM envelopes, which are way too slow. You need to sample/rip sounds from SID tunes.
4.1 Do not use volume commands or instrument volume for "mixing" your channels. Do the balancing in the arrangement or inside the sample! That's the SID way. You can use instrument envelopes, if you can explain how the SID's hardware envelope could do that. But for example if you have a snare instrument sample, you must only play that sample with maximum volume.
5. Analog filter: cannot be done with existing features. You have to sample/rip SID tunes.
6. Ring modulation: cannot be done with MilkyTracker, so you have to sample/rip SID tunes.
Also: limit your expressions to things that can be done with the SID chip. Do not use stereo sound, because the SID is mono. Use max 3 channels. Only use samples from SID tunes or single waveforms, etc. Do not use volume commands.
