Getting max and min values from a ring buffer

1

I am working on a Ndef and I would like to store the spectral flatness values in a ring buffer. Then I would like to extract the max and min values from that buffer:

(
Ndef(\bassFeedback, {
	var fb=LocalIn.ar(2).tanh;
	var chain=FFT(LocalBuf(1024), fb);
	var flat=SpecFlatness.kr(chain);
	var sampNum=1000;
	var ringBuf=LocalBuf(sampNum,2);
	var writeBuf=BufWr.kr(flat, ringBuf, Phasor.kr(0,ControlRate.ir/1000,0,sampNum));
	
	var x=SinOsc.ar(
		LFNoise0.kr(1/4).exprange(50,80), 
		fb.abs*SinOsc.ar(
			1/8, 
			[fb[0].abs, fb[1].abs*pi], 
			1, 
			fb).range(1,8),
		1,
		fb
	);
	LocalOut.ar(x);
	// buf.maxSubclassIndex.poll;
	x
} * -32.dbamp
).fadeTime_(1).play
)

1st question: is the control rate ring buffer correctly implemented?
2nd question: how to get the max and min values from the ring buffer?

Thanks!

2

Why not just send them back to sclang? There is only new data every 1024 samples.

3

At 44.1 kHz and a 64-sample control block, ControlRate is 689.0625 – divide by 1000 means that it will advance 0.6890625 buffer positions per control block… I’m guessing that’s not what you want?

Why not Phasor with rate = 1?

sc3-plugins has BufMin and BufMax UGens.

hjh

4

Thanks, BufMin and BufMax is exactly what I need! I have an issue with the left and right channels though. As far as I understand, FFT doesn’t support multichannel expansion right?

So I can use two chains:

(
Ndef(\bassFeedback, {
	var fb=LocalIn.ar(2).tanh;
	var chainL=FFT(LocalBuf(1024), fb[0]);
	var chainR=FFT(LocalBuf(1024), fb[1]);
	var flat=SpecFlatness.kr([chainL,chainR]);
	var sampNum=1000;
	var ringBuf=LocalBuf(sampNum, 2);
	var writeBufL=BufWr.kr(flat, ringBuf, Phasor.kr(0,1,0,sampNum));

	var x=SinOsc.ar(
		LFNoise0.kr(1/4).exprange(50,80),
		fb.abs*SinOsc.ar(
			1/8,
			[fb[0].abs, fb[1].abs*pi],
			1,
			fb).range(1,8),
		1,
		fb
	);
	LocalOut.ar(x);
	BufMin.kr(ringBuf).poll;
	x
} * -32.dbamp
).fadeTime_(1).play
)

The values on the second channel don’t seem correct, I wonder why is this the case…

5

Here, it would be helpful to read the help files for BufMin and BufMax – they explain that these UGens don’t split out the channels. You should use two mono buffers instead of a single stereo buffer.

hjh