A more accessible NSF sound?

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Dermot
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A more accessible NSF sound?

Postby Dermot » Sun Oct 28, 2018 11:23 pm

I'm a chiptuner. I've done a lot of chiptunes, mostly in FamiTracker but also increasingly in 0CC-FamiTracker, too. But this isn't about the trackers themselves, as much as it is about the exported chiptune sounds.

You see, I'm from a family of sensitive ears. For me, it helps aid my sensitivity to sounds and helps makes me a better a musician. But for some of my other family members, it means they can't listen to any of my chiptunes themselves because square waves, triangle waves and sawtooth waves with their pointy waveform edges are painful to their ears. They can appreciate my musical ability itself and the technical achievement, but the bleeps and bloops themselves are ear sandpaper and they can't sit through them. Even my brother played plenty of 8-bit NES games back in the day, but always had the volume on mute for this reason. (There's a deeper genetic issue involved - some people in my extended family were born deaf.)

I've been trying to investigate an alternative to traditional pointy-edged geometric chiptune synthesis. My brother wondered why I can't just make music with sine waves, whose waveforms are completely curved and much gentler to the ear, but as far as I know you can't do the different square wave duty cycles in sine wave. But what I really wonder is if (and how much) it is possible to filter conventional NSF audio recordings so they don't have pointy-edged waveform patterns. If there are filters in audio editors like Audacity that can accomplish this.

But what might be even more interesting, is a more "accessible" kind of chiptune playback, where each of the channels go through (perhaps) a bicubic interpolation filter to round their edges, and thus our homemade NSF chiptune music can be enjoyed by audiences (and loved ones) with ears too sensitive for the traditional sound. At this point I'd consider that more of a pie-in-the-sky wish, because someone would have to first care, and write and maintain the software, and understandably if it sounds too different from real NES audio, most people wouldn't be interested in it. In the meantime I'd settle with filtering individual chiptune channel playback recordings manually with third-party software and then mix them together...if I knew how.

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Teuthida
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Re: A more accessible NSF sound?

Postby Teuthida » Sun Oct 28, 2018 11:38 pm

NSFPlay has a configurable lowpass filter in its settings menu that let you soften the sound of your sound file. If you're looking for a softer sound overall, you might want to look into the VRC7 chip, which produces sound by transforming sine waves.
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Dermot
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Re: A more accessible NSF sound?

Postby Dermot » Mon Oct 29, 2018 12:02 am

Tell me about this lowpass filter. What would I have to do to make the waveform's pointy edges round?

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Teuthida
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Re: A more accessible NSF sound?

Postby Teuthida » Mon Oct 29, 2018 12:19 am

If you set the lowpass filter in NSFPlay to maximum strength, it will soften the waveforms significantly and make them closer to sine waves, which is what you wanted.
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Dermot
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Re: A more accessible NSF sound?

Postby Dermot » Mon Oct 29, 2018 12:44 am

Thank you, I'll try that.

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TechEmporium
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Re: A more accessible NSF sound?

Postby TechEmporium » Fri Nov 02, 2018 10:25 pm

Well, if I may add something here...

It's not that the NSF specification itself isn't "accessible," as much as it is the technical limitations of the original hardware. VRC7 itself, as Teuthida suggested, would be a good starting point when it comes to creating music that won't grate sensitive ears, but then you'd be limited to VRC7 sound channels if that's all you'll be composing in.

I have a couple of tips... The DPCM channel that can help to dull out the triangle wave through sample playback. Check out the attachment to see how you can accomplish that, as well as rudimentary volume control on the triangle wave (it's not real volume control; it's just the use of 2 DPCM samples to play the triangle wave at a normal or a quieter state). Also note that I'm using the triangle wave to play notes at lower octaves on the scale; the higher the notes, the worse it would get with sensitive ears. This last tip here also applies to the sawtooth wave on the VRC6 sound chip, except you also have the advantage of using proper volume control on that channel; lower the volume & do your best to work with lower octaves on the sawtooth channel.

The most shrill sounds you can also get are from using the square channels of any chip; on the 2A03/MMC5 square & VRC6 pulse channels, the default duty cycle is 12%. Not only would adjusting the volume help, but so would bringing the duty cycle of each square wave closer towards 50% (if not at 50%). When you have a square wave at 50% duty cycle, it's like having a very loud sine wave clipped off due to over-amplification, so even though the volume's louder, the sound will be softer & duller to the ears. You can adjust the duty cycle of the notes in the square wave channels either through adjusting the instruments, or through using the Vxx effect next to each note (V01 & V02 in the 2A03/MMC5 square channels bring the duty to 25% & 50% respectively, while the VRC6 pulse channels use finer tuning... V07 brings the pulse width to 50% duty cycle).
Attachments
triangle_volume_test.nsf
(4.87 KiB) Downloaded 2 times
triangle_volume_test.ftm
(2.63 KiB) Downloaded 2 times
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Re: A more accessible NSF sound?

Postby TechEmporium » Fri Nov 02, 2018 11:59 pm

To add to this, here's another sample song that can illustrate my tips a bit better.

I've set the instrument's duty cycle to 50% (which is like typing V02 in the effects column beside the first note of both square channel). I've also made sure that the volume of my lead melody's square channel isn't at maximum (15 or F,) but at 10 (or A,) while the second channel's maximum volume is at 6. As for the triangle channel, I've used it for bass & none of the notes exceed an octave of 3, giving it a deeper sound that's not as shrill to the ears.

Another important thing I forgot to mention; if you have 2 sound waves of a similar volume, note, octave & at times duty cycle, when they both play at the same time, their collective volume increases, as the waves build onto each other. So if you play a C-3 in both square channels with a volume F, at the same duty cycle, the result would be a C-3 playing at the equivalent of volume level 30 (1E) & that makes matters worse for your ears. So, be mindful of volume with respect to a note's octave & a sound wave's duty cycle. This is also why, for the most part, my second square channel plays at a lower octave than the lead melody's channel.
Attachments
Spirit Of A Lost Troubadour.nsf
(5.61 KiB) Downloaded 2 times
Spirit Of A Lost Troubadour.ftm
(8.26 KiB) Downloaded 3 times
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