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Rub_0201
Registered: Apr 2019
Posts: 18 |
How to mute the voices of the SID?
Hi!
I want to remix my favorite SID tunes. A lot of them have nice rhythm, ideas and melody, but if I hear them more then 10 times in a loop, I get dizzy.
I want to bring more stillness and a different temper in them - making a remix.
My idea is to mute one or two of the voices of the SID and additionally fiddle around with some registers.
I did that with emulators like the C64debugger("24Hours Demo Remix" on YT) and the result is quite nice. Now I want to do it on the C64 itself.
As I am no SID programmer or musician, I have no clue how to do it on the real machine.
I understand fundamental assembly coding, but I am far from doing fancy stuff.
So I need your help! |
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spider-j
Registered: Oct 2004
Posts: 498 |
@Rub_0201:
Could it be that that sidplay2 is configured to emulate 6581 SID and your VICE to emulate 8580?
Your recordings from VICE could be 8580 "filter holes" because on 6581 cutoff values from $00 are audible and on 8580 only values from $01. Although even listening to it with proper 6581 emulation the SID voice 3 does sound a bit weird. So I'm not really sure about that. Maybe not the best test case.
To get your routines right I'd start with
1.) a SID tune that doesn't use filters at all - so the even most crappy emulation shouldn't have much problems to playback
2.) and then a SID tune that uses "mild" filters AND only compare results with a somewhat current SID emulation
Another problem with the tune you're referring to is, that is was done in GT1 and nobody other than the author knows if it was ever tested on real hardware. So it may be that it sounds "better" on old / outdated emulation, because it was composed on old / outdated emulation :-) |
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Burglar
Registered: Dec 2004
Posts: 1101 |
you can mute channels with JSIDPlay2 V4.10, and u can also export to wav. personally, I only use the cli interface, but I guess same features are in the gui too. |
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Rub_0201
Registered: Apr 2019
Posts: 18 |
I hope, the emulator is acurate and the test results are similar on the real hardware.
I've set the SID to 6581 imho for the tests.
--------------------------
This song is a challenge :-) And I love this song since 35 years. Well, the Amiga version - Met Romeo Knight on X2023.
Challenge accepted - I used C64 Debugger to see the timing of the IO Writes and the new version of my play routine is good enough now!
Voice 3 only:
https://www.dropbox.com/scl/fi/adcy922bq5j06hmsqofxc/Rub_V2_vic.. |
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Rub_0201
Registered: Apr 2019
Posts: 18 |
Testing some more songs, stumbled into klicking noise in NE7 "Cargo".
This time it is Voice 1:
https://www.dropbox.com/scl/fi/6nm77bidyfcccu0dc54fc/Rub_NE7-Ca..
Is it the same playroutine? Yes, SIDPlay says Goattracker V1.x as on "Beat to the pulp". |
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Mixer
Registered: Apr 2008
Posts: 452 |
Clicks and snaps are part of SID music :) You may also notice differences due to the ring and sync modulated sounds. They need the other sid voice oscillator active, using correct waveform and frequency. In that case you may have to use some other method to mute the channel. Perhaps ADSR to 0 or the filter as aeeben mentioned. |
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Rub_0201
Registered: Apr 2019
Posts: 18 |
Ahh, now it makes klick ;-)
Good to know, @Mixer, the klicks in that instrument are not intended and they apear also with all voices playing. |
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Hoogo
Registered: Jun 2002
Posts: 105 |
Is it common that players access SID registers only once each call? If there were more, then the first access would be lost. |
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chatGPZ
Registered: Dec 2001
Posts: 11386 |
Most "modern" players do. However, lots of old players write them more than once - or even read them |
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spider-j
Registered: Oct 2004
Posts: 498 |
Quoting MixerClicks and snaps are part of SID music :)
After looking at the actual filter programs I'm pretty sure that the author just had either a completely special 6581 or no real 6581 at all and the old emulation at the time of GT1 was misleading.
Turning on / off filters on one voice in such a manner is something you can only do safely on a 8580.
I know, 6581 fans don't like to hear it, but the 6581 was just "broken" (volume/filter switch clicking, mixed waveforms not working, unpredictable filter curves, etc.) and the 8580 is the way the engineers wanted the SID chip to be. |
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chatGPZ
Registered: Dec 2001
Posts: 11386 |
Quote:mixed waveforms not working
They don't work (as intended, or even as documented) on the 8580 either - that they produce a "better" audible result on 8580 is purely a side effect of the different manufacturing process (there is no "fix" for this in the 8580) :) |
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