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SIDWAVE
Account closed
Registered: Apr 2002
Posts: 2238 |
How many BPM is a C64 or HardSID ?
[03:19] <rambones> any geniousses ?
[03:19] <rambones> how many bpm is a C64 raster irq ?
[03:20] <rambones> or as i this case. the music is at 51 hz... so i wanna find the sync to the beat
See. i wanna sync a sampled sid to the tracker..
So... it was sampled with HardSID which is 51 hz..
It must be around 120-130... but i am uncertain..
No clue what to google for |
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wacek
Registered: Nov 2007
Posts: 509 |
I had similar problems when porting music from other non-standard tools (jeskola buzz) into Ableton Live. The best way IMHO is setting the BPM value as a rough estimate, and then syncing manually the beat at the end of your sequence, using Live's very friendly user interface :) If you keep looking for a perfect value to enter in the clip properties, you'll never find it to my experience.
This method is much faster works best for me so far, like I said not only with 64 recordings, but also whenever you're doing a mix from different sources (analog/digital, vinyl, live music etc). |
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Graham
Account closed
Registered: Dec 2002
Posts: 990 |
Quoting (451)
My song tempo is 07 (in SID Wizard) and my beat is 6 lines.
7*6=42 (frames per beat)
3060/42=72,8571 BPM
Right?
PAL C64 has a base clock of 17734475 Hz, system clock is 1/18th of that. Clock cycles per frame are 312*63.
Framerate of the C64:
17734475 / (312*63*18) = 50.125 Hz
Quoting (451)When I play it back in Ableton Live with 72.86 it's not quite right, it plays a bit too slow, and it's more than just that 0.0029 difference. So I tried recalculating it with 3000 instead (71.43 BPM) and it gets better (the sync gets disturbing after about 3 bars 4/4 time instead of half a bar).
Per minute:
(17734475*60) / (312*63*18) = 3007.474 Hz
Divided by 7*6 = 42:
(17734475*60) / (312*63*18*42) = 71.607 Hz
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(451)
Account closed
Registered: Mar 2012
Posts: 3 |
Graham:
71.61 BPM (since I only can set two decimals) works REALLY well, thanks for explaining!
wackee:
Since I use Live mainly as sequencer I think I'll just fine-adjust the clips manually where needed, but that method might come in handy for future projects, thanks! |
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ChristopherJam
Registered: Aug 2004
Posts: 1403 |
Perhaps run off CIA instead of VIC?
Given that the system clock is (17734475/18)Hz, one fiftieth of a second passes every (17734475/18/50)=19704.972 cycles.
If you run the music routine off a CIA interrupt set for 19705 cycles, that'll get you a play rate of (17734475/18/19705) = 49.9999Hz, or 2999.996 ticks per minute.
At 24ppq, that's a speed of 124.9998bpm - that should drift by less than half a millisecond over the course of a five minute 125bpm track. |
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Mace
Registered: May 2002
Posts: 1799 |
Why sync the PC to the C64 and not the other way around? |
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