Disabling/Enabling recording into a buffer without loosing timing

Questions
1

Is there a ugen or a method with existing ugens to enable and disable circular recording into a buffer without loosing timing? For instance, if I use BufWr with a phasor, the only way I know how to (almost( stop recording is by setting the phasor to a single frame, but this will cause a discontinuity if reading from that frame. With RecordBuf I can use run to stop and start recording but as far as I can tell, not without loosing timing.

2

One way is to have a separate synth that reads from buses for phasor and audio signal, and uses bufwr to write the signal. Then you can free that synth to stop recording, and make a new synth to start it again (or pause/unpause the node)

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3

I have a recordMix parameter, which crossfades between BufRd from the circular buffer (at recordMix = 0) and the live input (at recordMix = 1). Then BufWr writes the crossfade result into the buffer. So itā€™s possible to do feedback that way :wink: but in practice, I never did. I do think itā€™s nice, though, when disabling recording, to ramp this parameter and smooth out the discontinuity.

Ericā€™s modularized solution is a good design, too.

hjh

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4

Yes, that sounds like a good solution even though I would love to have it in one synthdef.

5

For my case I would still want whatever is in the buffer at the time of ā€˜freezeā€™ and not overwrite it with live input or am I misunderstanding your approach? I am not listening back from the synthdef which records to the buffer but using other synthdefs to index into the buffer.

6

Actually after thinking about at bit your approach is the way I will go, having one server-clock which feeds different synths sounds like the best way to keep everything in sync, plus the pause/resume scheme sounds easy. I will give it a try.

7

Misunderstanding ā€“ youā€™re assuming that the BufRd I mentioned is an output, when Iā€™m using it as the ā€œnon-liveā€ input to the crossfader.

Pseudo-code (not at the computer):

phase = Phasor.ar(yadda);
oldBufferData = BufRd(at phase);
liveInput = In.ar or whatever;
signalToWrite = XFade2(oldBufferData, liveInput, recordMix * 2 - 1);
BufWr(signalToWrite, at phase);

hjh

8

Ah I get it now, thanks.

9

In case itā€™s useful, one way to stop BufWr from recording is to use 2 buffers and change to a different buffer when you donā€™t want to record into the first one. Then you can leave the Phasor as it is.
This example uses Select.kr with LFPulse.kr to change the buffer while recording:

// allocate buffers
s = Server.local;
s.sendMsg("/b_alloc", 0, 44100 * 2);
s.sendMsg("/b_alloc", 1, 44100 * 2);  // extra buffer 
)

//write into alternating buffers with a BufWr
(
y = { arg rate=1, bufNumA = 0, bufNumB = 1;
    var in, env, bufChoose;
    in = SinOsc.ar(LFNoise1.kr(2, 300, 400), 0, 0.1);
	env = Env([1, 1], [2]).ar(2);  // 2 sec env
	bufChoose = Select.kr(LFPulse.kr(4), [bufNumA, bufNumB]);
    env * BufWr.ar(in, bufChoose, Phasor.ar(0, BufRateScale.kr(0) * rate, 0, BufFrames.kr(0)));
    0.0 //quiet
}.play;
)

//read it with a BufRd
(
x = { arg rate=1, bufNumA = 0;
    BufRd.ar(1, bufNumA, Phasor.ar(0, BufRateScale.kr(0) * rate, 0, BufFrames.kr(0)))
}.play(s);
)

Best,
Paul

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