Is there any VST that converts an input into a delta modulated signal?

It's the same system that the Nintendo NES uses to play samples.

Basically it's a 1 bit stream of audio that either tells the amplitude to go up or down each cycle depending on how fast the cycles are processed.

Is there anything like this?
Last edited by clayman256 on Sat Jun 02, 2012 3:04 am; edited 1 time in total

Hi clayman—could you tell me why you'd like to do this? Just curious—not making any implied judgement. Do you want some slew-limiting distortion, for instance? It seems that delta-mod, in its most shining implementations, tries to be what PCM is. So, I'm assuming you want some of the negative qualities as an effect, maybe? That is, I suppose you mean to put full samples into it, and get full samples out of it, but do a delta-mod in between. Am I reading your correctly?

I remember Stephen St. Croix, in the 70's at AES, hawking his Marshall Time Modulator, bristling as he described the shortcoming of his digital competitor and the horrors of their delta modulation...(and I really liked the MTM back then, btw, and was fortunate to have access to one at the electronic music lab...)

I want to record of use an input stream through something that simulates delta modulation. I want to use it as a lo-fi effect reminiscent of the NES's Delta Modulation channel.

I found this which does it with WAV files, but I'd like one for incoming inputs.
http://www.mattmontag.com/projects-page/nintendo-vst

This is basically what happens in delta modulation:


In a conversion of a signal, the delta modulated signal either rises or falls each interval, hence a 1 bit modulation of the waveform.





It's a really neat form of sampling compared to sample/bit crushing.

OK, that's what I was alluding to when I asked if you were after "slew [rate] limiting distortion". It wouldn't be difficult to do at all. In a quick search for "slew rate limiting vst", I came up with this as the first link:

http://bedroomproducersblog.com/2012/01/30/studio-machina-re leases-sl-500-freeware-multi-band-limiter-vst-plugin/

"Studio Machina Releases SL-500 Free Slew Rate Limiter VST Plugin"

I don't know if that will give the effect you're after, but you might try searches along those lines.

Thanks! This could simulate the timing of rising the waveform up and down. I could probably throw a sample rate and bit crusher after it.




That would be spot on. Can't wait to see this plugin when it's released!

If you have Chipsounds you can do this already, if you're willing to edit a text file (I managed it, so you probably can too). This'll also let you switch between C64-style 4-bit modulation (which is brighter and crunchier) and NES style (which is very muffled, and looks like a modulated triangle wave almost). You can only use it on pre-recorded waves in a certain folder, but the upside is it's instant authenticity if that's what you're going for.

The Shortcircuit sampler features a slew limiter as one of it's insert filters. I've found this really useful for grunging up beats and you can modulate it with LFO's, envelope followers, etc, but obviously, it can only affect stuff you've made in the sampler.

EDIT: If you have Spectralworx, I also noticed the other day it has a slew limiter, which lets you set different rates for upward and downward parts of the waveform. This can create some VERY messed up effects

There's this:

http://www.savioursofsoul.de/Christian/vst-plugins/#SigmaDel ta

Don't know if it does exactly what you want though.

I just threw one together out of mild curiosity of how it sounded compared to traditional sr/bit-reduction.

extremely crude / very untested / at your own risk, etc.

http://www.xferrecords.com/freeware/DeltaModulatorPC.zip (x32 x64)
http://www.xferrecords.com/freeware/DeltaModulatorOSX.zip (vst and au)

-Steve

Hi David,
Any ETA on this? I have chipsounds and love it but this seems like a great
extension of the vibe.
Cheers,
Scott

Most of the processing stuff and impulses are done. We are working on the UI and presets at this point. We hope to release it in a few months.

Cheers

I'll definitely be checking it out. Looks amazing.








Wow, that plugin is really nice! It simulates the characteristics pretty nicely. I'll be using this for some stuff. I like how the slew rate is in sync with the bit depth so you can never rise of fall more than 1 quantity at a time.

There is one thing I have to mention though.
One of the things that real Delta Modulation does though, is that the fact that since it is a constant amplitude modulation from a 1 bit stream, the bit either tells it to go up or down in an interval.
This means that the waveform is constantly moving up or down.

This means even in silence the waveform is moving up and down each interval.

In short: It can never be the same amplitude twice.

Basically if it was a flat input it would dither up and down each interval if it was already near the amplitude of the input.



Notice at the end of the sample, the modulated form dithers back and forth to be as close to the amplitude signal as possible.



I am still very impressed by your plugin though, it's just that I wanted to point out that actual DM does that.

Cheers, glad you like it - I did have it act like that at first, but it would whine when input was silent, which I thought wasn't very nice, not to mention people would think it is a bug..

I was thinking to add a switch to toggle that behavior, and maybe a second switch to gate when input is silent for a certain number of samples... shouldn't take long, I'll report back when I've done so.

That would be amazing! But seriously, I'm really thankful for this plugin. It sounds like a really good simulation compared to when I used an real DM encoder in FamiTracker.

The reason why there's no hum in, say, NES music with DM samples is because the channel is silent when the sample is done, and most samples are cut out at the silence, for both that reason, and to save ROM data.

didn't take too long - uploaded to same locations (you should see 2 switches on the GUI along the top now).

Glad you like it, wouldn't exist without your post, so use it with pride
-Steve