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Noise Test Program
http://forums.nesdev.com/viewtopic.php?f=22&t=16708
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Author:  rainwarrior [ Thu Nov 16, 2017 11:11 am ]
Post subject:  Re: Noise Test Program

Hrm, I didn't really see that as a problem, directly.

I mean that's a general problem with any emphasized harmonic that's not a power of two (or three is close), a lot of acoustic instruments have resonance that does that kind of thing... but I don't think it's unacceptable in most cases. E.g. I've played a marimba with very strong 5th harmonics, where if you wanted to focus on it you can listen to that tone instead of the fundamental, and it's completely out of tune with anything else playing with it. In context though, the other sounds guide you to the "correct" hearing of it and the out of tune harmonics are sort of de-emphasized psychologically, just one of the "non-tonal" components to the sound.

The noise channel does have the problem that you can't really control which loop you're going to get, but you could probably mitigate that issue just by letting it run in non-periodic mode to continually "randomize" between periodic tones. The majority of tones will establish the 93 step pitch.

Author:  lidnariq [ Thu Nov 16, 2017 11:39 am ]
Post subject:  Re: Noise Test Program

rainwarrior wrote:
The majority of tones will establish the 93 step pitch.
About 91% of the time... Out of the 32767 valid states for the LFSR, 2976 of them have the three-times-as-loud 31st harmonic. I guess that does seem pretty safe.

(By which I mean, when the 31st harmonic is present, it's 2.8x or ~9dB louder than any other harmonic component.)

Author:  Pokun [ Thu Nov 16, 2017 12:16 pm ]
Post subject:  Re: Noise Test Program

BTW anyone knows some licensed Famicom or NES games that use looped noise? All I could think of was Megaman 1 (Fireman music), Megaman 2 (Quickman music) and Balloon Fight (Game Over music, probably unintentionally). The guy that wanted to test this on his square button Famicom had a lot of games but not any of these.

Author:  FrankenGraphics [ Thu Nov 16, 2017 12:55 pm ]
Post subject:  Re: Noise Test Program

B00daws' tune sounds pretty amazing, although it would be rather impractical to run the audio engine at x6 speed. Sounds much like printer and floppy drive music, and it should, because what B00daw seems to do is start-stop alternate the channel just like the servo of a any such devise would (at least that's my understanding how they work).

Yeah, solstice is a great one. Very nice use of (orchestral) triangle. Part of it comes from it being a bit varied in different parts, and part because it is allowed to play solo here and there, i think.

That megaman tune (quick man) is a little above my threshold; wouldn't want to listen to that track outside its context. The off-pitch tuning is just too apparent. :S

The higher end pitches definitely have a bit of the character the cymbals' bell part. It might sound even better if you have a separate noise channel (Pretty obscure case: Sunsoft 5b) on an external synth chip and use the 93 noise for the bell decay, simultaneously. Harder hits = the drum stick hit closer to the center of the cymbal.


pokun wrote:
BTW anyone knows some licensed Famicom or NES games that use looped noise?

Aforementioned Solstice, main gameplay theme. I think it sounds off in this NTSC playback, though. It must've been composed for PAL. (warning: subjective random thought. i don't know what tim follin actually thought, of course. but i'd assume they used a PAL unit for testing.) Edit: Ninja'd.

Author:  thefox [ Thu Nov 16, 2017 1:31 pm ]
Post subject:  Re: Noise Test Program

FrankenGraphics wrote:
pokun wrote:
BTW anyone knows some licensed Famicom or NES games that use looped noise?

Aforementioned Solstice, main gameplay theme. I think it sounds off in this NTSC playback, though. It must've been composed for PAL.

Sounds like bad filtering in audio emulation, actually. Here's a gameplay capture from the original machine: https://youtu.be/fXQDpxTkCAA?t=66 (although this one in turn suffers from audio compression).

Author:  FrankenGraphics [ Thu Nov 16, 2017 1:38 pm ]
Post subject:  Re: Noise Test Program

Yeah, your link sounds more au naturel. Thanks! Why would anyone EQ a song, especially by so much, before uploading? :cry:

Added this in an edit, but then you posted. Pasting the relevant piece here instead:

found a quote. "[...] if i typed in '42, 100', '42' would be the note and '100' would be the duration in cycles per second (in the uk, 25 would be one second). So I never knew what key or tempo I was writing in [...]". If it's about the same period, PAL seems to be the target platform, but tempo not an active decision.

Author:  rainwarrior [ Thu Nov 16, 2017 1:56 pm ]
Post subject:  Re: Noise Test Program

FrankenGraphics wrote:
Yeah, your link sounds more au naturel. Thanks! Why would anyone EQ a song, especially by so much, before uploading? :cry:

It's not really "EQed", I think that's just pretty typical results of using the RF modulator output, plus maybe degradation from being recorded to whatever intermediary forms before becoming a 240p-quality YouTube video.

As an aside, you can also see those 6-pixel wide diagonal stripes a lot (esp. title screen, pause map/menu) since they used checkerboard dithering extensively. (Also, several screens of the game have garbage in the top row of tiles, which is likely to be covered on NTSC but more often visible on PAL, AFAIK.)

I'm not sure whether it can be said to primarily target NTSC or PAL. It was developed in England, but released in North America many months before it was in Europe. I think they were pretty savvy about testing on both by that point. (Though on the issue of tempo, I think they just did a "don't care", and it's slower in the PAL version.)

There was also a short making-of promotional video made, where it looks/sounds like Tim's music demo is NTSC: https://www.youtube.com/watch?v=894_PNqBkx4

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