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PostPosted: Tue Jun 12, 2018 1:26 pm 
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Are these samples explicitly open-source / free to use?

I am working on a music related NES project, and I might be able to use these as a pseudo 2nd triangle channel.

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PostPosted: Tue Jun 12, 2018 1:31 pm 
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dougeff wrote:
Are these samples explicitly open-source / free to use?

lidnariq provided the script that generated them, so yes they're open source: http://forums.nesdev.com/viewtopic.php?p=154032#p154032

I don't think any license was explicitly stated but I suspect that it's not really possible to copyright a triangle wave anyway?

One thing you might try to take into account if trying to build a more practical version is that the samples have a volume that is kind of determined by the divisor of its sample period, so the volumes are very mismatched between different samples. (The timbre varies too.)


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PostPosted: Tue Jun 12, 2018 2:35 pm 
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1- I think they probably count as "math", so not copyrightable
2- If they are, I'm certain there's prior art to my instance
3- as far as I am concerned, they're public domain / CC-0 / WTFPL as you wish.


Different timbre? Oh, right, there's
A- weirdness with odd divisors (because ÷3 when quantized has to be 001101), but this gets more and more subtle the larger the divisor.
B- the stairstep harmonics because it's DPCM: The ÷2 case is necessarily just a square wave, and the larger the divisor the subtler the distortion and louder the triangle wave.
C- clipping with divisors larger than ÷62 124

edit:
rainwarrior wrote:
Well, lidnariq's goal was to provide every possible usable sample that evenly divides the available sample lengths.
Where I chose "usable" to mean "within 7 cents of A440 12-TET". Some of the other divisors (e.g. ÷7, ÷11) just don't fit into 12-TET, but might fit into 17-, 19-, or 24-TET...

.. has anyone written chiptune music that uses these microtonal temperaments? I guess I just found Sevish, who's done a bunch of random things, including 10-TET FM and 13-TET PSG...


Last edited by lidnariq on Sun Jun 24, 2018 3:58 pm, edited 1 time in total.

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PostPosted: Sun Jun 24, 2018 1:08 pm 
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Apropos of
But it'll eventually be an easy check up if the tuning sounds too raunchy or not once i get back home in august. But i'm pretty sure i need to either use another of lidnariqs' samples for my B-2 that doesn't use sample rate $C as a divisor, or if it still would sound too raunchy on PAL, come up with separate instrument lists for PAL and NTSC.
it's trivial for me to generate a new table for 2A07 tuning, so here's the perl, HTML table, dmc files, and the DPCM import script (h/t rainwarrior for pointing that that could be a thing) for same.

There's a few differences, primarily:
* Rate #4 (÷276) is usually only useful for a single pitch, but there are a few divisors where rate #12 (÷98) is also in A440 12TET. (Unfortunately, rates #4 and #12 are an octave plus a tritone apart, 1793 cents)
* Rates #7, #8, #9, #11, and #15 are all about 6-8 cents more sharp. Rates #7 and #15 are mostly unaffected (being a little flat on 2A03), rate #11 is improved (being too flat on 2A03, so 2A07 in A440 12TET) but rates #8 and #9 are moved out of A440 12TET.
* Rate #14 is 23 cents more sharp. This causes more notes to be in A440 12TET, but they're not the same ones as in 2A03 tuning.

.... of course, I tried to run my generated DPCM import script and famitracker crashed.


Attachments:
File comment: To regenerate import.txt, concatenate "dpcmdef" then "keydpcm"
calculate-chip-dmc-triangle-waves-PAL-tuning.7z [10.19 KiB]
Downloaded 1 time


Last edited by lidnariq on Sun Jun 24, 2018 1:21 pm, edited 1 time in total.
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PostPosted: Sun Jun 24, 2018 1:15 pm 
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lidnariq wrote:
.... of course, I tried to run my generated DPCM import script and famitracker crashed.

I think there's a limit to how many notes you can stick in a single instrument, at least I ran into a crash when doing that earlier, which is why I split the instrument into 2 halves.


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PostPosted: Sun Jun 24, 2018 1:19 pm 
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I was trying to divide the instruments into ranges that covered overlapping groups of 2 octaves of divisor, to try to minimize volume and tone color changes within an instrument... but without even a message to start debugging what went wrong I'm kinda inclined to stop trying.


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PostPosted: Sun Jun 24, 2018 1:53 pm 
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Thanks, lindariq! That saves a lot of manual labor, again.

I wouldn't worry about the auto-import. It's not much of a job to hand pick some with those tables as a guide.


It looks like i may be able to make a fairly region-consistent version of the song without exploding the filesize too much. I estimate going from 132 to 626 bytes for all the divisor samples needed if the sound of it checks out fine, or if not, some more. As a bonus, the note range will be a bit more complete, perhaps for use in some other song.

I suppose keeping the size super small is a criteria that mostly applies to the scenario where music using .dmc:s is everywhere (since they'd then need to be accessed everywhere), but since i've isolated use of them to menus and perhaps story, i probably don't need to be that frugal.

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