Audio Stream as FM Carrier?

[Perfect Human Interface]

Hey, so I've been doing some frequency modulation stuff as an effect plugin. It's really straightforward to use the input audio as the modulator and an osc as the carrier (stream in to the osc frequency). Any thoughts as to how I might be able to use the audio stream as the carrier and the osc as the modulator? In other words, how could I control the frequency of an audio stream?

Since frequency is basically playback speed in this case I guess I would have to introduce some kind of delay since I can't push audio forward in time, but beyond that I'm pretty lost.

I downloaded and was playing around with this modulation vst plugin that lets you swap the sources between carrier and modulator at will, and I'd like to be able to do the same.
http://www.niallmoody.com/ndcplugs/themodulator2.htm

Think it's doable?

[stw]

You can try to run your audio carrier through a pitch or frequency shifting algo and modulate that. I'm doing some similar stuff in my current plugin.
Search for it at the SM Forum. There's some valuable stuff.

[trogluddite]

In essence, all you need is an "Interpolated Delay" - and use your modulator to modulate the delay time, effectively speeding up and slowing down the audio, much like a "vibrato" guitar pedal would do.
What is tricky is to calculate the precise amount of pitch shift- it won't be just proportional to the delay time, but also the speed of modulation - i.e. it is proportional to the rate of change of the delay time, so as your modulator rises in frequency, you need a lower amount of modulation to get the same min/max frequency shift.

[Perfect Human Interface]

In essence, all you need is an "Interpolated Delay"

Thank you! I hadn't come across this module yet (or if I had I didn't understand its significance). This is super useful.
After some time dicking around I now have most delicious FM sounds.
and re: calculating the precise amount of pitch shift-- no need. It's just another variable to tweak, so I slapped a knob on it (0 - 20,000 woo!).

[billv]

all you need is an "Interpolated Delay" - and use your modulator to modulate the delay time

Don't know what a "Interpolated Delay" is, but found one in my SM toolbox-alien code version with no name.
Sure enough Trog, hooked it up to a modulator and I've got a small Vibrato Effect happening.
Perfect base to start experimenting from. As I hardly work in blue, this is great for me.
So Thanks Trog, and don't tell me how to make it better yet. I'd like to stuff this one up on my own for a
couple of weeks.

And guitar players always love Vibrato FX...
Cheers

[Perfect Human Interface]

and I've got a small Vibrato Effect happening.

It's great for analog tape sounds!