| |
TWW
Registered: Jul 2009
Posts: 545 |
The old PAL/NTSC question
Hiho
So I was fiddling around with a v-sync'ed / fully stabilized NMI timer in conjunction with IRQ timers so that any screen effect can be controlled by a tight NMI while music is played by a CIA timer (which would allow you to adjust the timing so the player routine is called at the same intervall pr second on all models).
Now I would like to test this and there are a couple of issues which needs to be ironed out (Disclaimer, I know fuck all about music):
#1 - As I understand it by reading this forum, it is not enough to call the routine at a fixed / pr. second interval, you also need to change some of the note / frequency tables in the player routine itself. Can someone confirm and elaborate?
#2 - Given #1 is neccessary, is there any SID available which could be used to test this, where the location and contents of these tables are known so it would be trivial to make said test? |
|
| |
Fungus
Registered: Sep 2002
Posts: 680 |
Yes the note tables aren't the same, the values are actually correct for NTSC as they are taken from the Programmers Reference Guide. On PAL they are out of tune, so when fixing I decided not to change them due to this fact.
If you happen to find a PAL tune with corrected note tables, then you would need to change them maybe, not that anyone will notice really unless they analyze the pitches externally, or have perfect pitch. |
| |
Krill
Registered: Apr 2002
Posts: 2968 |
Quoting Fungusthe values are actually correct for NTSC as they are taken from the Programmers Reference Guide. Wasn't there this story about HAL Labs Japan and composing tunes strictly by The Book, which came out utterly detuned in the end? :)
Might have been another case, though, like sticking to an early datasheet while SID changes were on the way, too.
But anyways, yes, the difference between NTSC and PAL isn't so big.
Having a different intonation would probably make more of a dent in a given tune. |
| |
Stone
Registered: Oct 2006
Posts: 172 |
Regarding #1: Unless you need the song to be in tune with a specific pitch (e.g A440), switching between PAL/NTSC won't make a difference in that will be in tune with itself, so to speak. I don't know of any games that were released with different pitch tables between territories. The HVSC guys would know.
In fact, if you decide to go down the route of creating new pitch tables you may end up screwing up the tune because some player routines use wave table instruments or fine detune with absolute values and they are in many cases going to sound "off" if they are not adjusted as well. |
| |
chatGPZ
Registered: Dec 2001
Posts: 11350 |
Quote:Might have been another case, though, like sticking to an early datasheet while SID changes were on the way, too.
The Datasheet contains the values calculated for a 1Mhz clock iirc - but more importantly, some values are actually wrong (iirc the first version of the Manual contains the same mistakes) |
| |
acrouzet
Registered: May 2020
Posts: 91 |
Quote: Quote:Might have been another case, though, like sticking to an early datasheet while SID changes were on the way, too.
The Datasheet contains the values calculated for a 1Mhz clock iirc - but more importantly, some values are actually wrong (iirc the first version of the Manual contains the same mistakes)
Funnily enough, the values that are wrong are just typos due to misread similar-looking characters (e.g. 8 turned into B, C turned into 0, etc.)
Galway used a more accurate 1 MHz A440 table early on though. in fact, nearly all 1 Mhz A440 tables in use are derived from him, rather than the datasheet. |
| |
chatGPZ
Registered: Dec 2001
Posts: 11350 |
I always wondered why the didnt print a small BASIC program in the Manual that calculates the note frequencies... instead of that giant table :) |
| |
acrouzet
Registered: May 2020
Posts: 91 |
Also, if we're talking about allegedly "out-of-tune" tables, many PAL A440 tables aren't the most accurate either, and nobody seems to notice.
(In particular, Rob Hubbard's table from 1985 is still in use today in tools like SID Factory II). |
| |
chatGPZ
Registered: Dec 2001
Posts: 11350 |
Speaking of that, did anyone yet come up with a table that shows least quantization errors (by carefully tuning it up or down a bit)? I did this on other platforms (where freq is even less accurate) and it did make a great difference. |
| |
acrouzet
Registered: May 2020
Posts: 91 |
Quote: Speaking of that, did anyone yet come up with a table that shows least quantization errors (by carefully tuning it up or down a bit)? I did this on other platforms (where freq is even less accurate) and it did make a great difference.
A friend of mine calculated one. In the end, it doesn't make a difference (at least to my ears) cause the SID has such a fine frequency resolution. |
| |
chatGPZ
Registered: Dec 2001
Posts: 11350 |
Yeah, perhaps doesn't matter much for SID. A tiny bit of detune can be good too :) |
... 7 posts hidden. Click here to view all posts....
|
| Previous - 1 | 2 - Next |
