rsc3/doc-schelp/HelpSource/Classes/PlayBuf.scrbl

#lang scribble/manual
@(require (for-label racket))

@title{PlayBuf}
 Sample playback oscillator.@section{related}
  Classes/RecordBuf, Classes/DiskIn, Classes/BufRd
@section{categories}
   UGens>Buffer


@section{description}

Plays back a sample resident in memory.

@section{classmethods}
 

@section{method}
 ar, kr

@section{argument}
 numChannels
Number of channels that the buffer will be. This must be a fixed
integer. The architecture of the SynthDef cannot change after it
is compiled.

@section{argument}
 bufnum
The index of the buffer to use.
@section{note}
 
If you supply a bufnum of a buffer with a differing number of channels
than the one specified in this PlayBuf, it will post a warning and output the channels it can.
::

@section{argument}
 rate
1.0 is the server's sample rate, 2.0 is one octave up, 0.5 is one
octave down -1.0 is backwards normal rate… etc. Interpolation
is cubic.


@section{argument}
 trigger
A trigger causes a jump to the startPos. A trigger occurs when a
signal changes from negative value to positive value.

@section{argument}
 startPos
Sample frame to start playback.

@section{argument}
 loop
1 means true, 0 means false. This is modulateable.

@section{argument}
  doneAction
an integer representing an action to be executed when the buffer is finished playing. This can be used to free the enclosing synth, etc. See link::Classes/Done:: for more detail. 
@racketblock[doneAction:: is only evaluated if loop is 0.

]
@section{Examples}
 


@racketblock[
s.boot // Boot the server, if you need to

// read a whole sound into memory
// note: not *that* columbia, the first one
b = Buffer.read(s, Platform.resourceDir +/+ "sounds/a11wlk01.wav"); // remember to free the buffer later.

SynthDef(\help_PlayBuf, {| out = 0, bufnum = 0 |
	Out.ar(out,
		PlayBuf.ar(1, bufnum, BufRateScale.kr(bufnum), doneAction: Done.freeSelf)
	)
}).play(s, [\out, 0, \bufnum, b]);
::

In the above example, note how the ]

@racketblock[doneAction: Done.freeSelf:: causes the synth to free itself when the buffer reaches its end.

Note again that the number of channels must be fixed for the SynthDef. It cannot vary depending on which buffer you use.

]

@racketblock[
// loop is true
SynthDef(\help_PlayBuf, {| out = 0, bufnum = 0 |
	Out.ar(out,
		PlayBuf.ar(1, bufnum, BufRateScale.kr(bufnum), loop: 1.0)
	)
}).play(s, [\out, 0, \bufnum, b]);


// trigger one shot on each pulse
SynthDef(\help_PlayBuf, {| out = 0, bufnum = 0 |
	var trig;
	trig = Impulse.kr(2.0);
	Out.ar(out,
		PlayBuf.ar(1, bufnum, BufRateScale.kr(bufnum), trig, 0, 0)
	)
}).play(s, [\out, 0, \bufnum, b]);


// trigger one shot on each pulse
SynthDef(\help_PlayBuf, {| out = 0, bufnum = 0 |
	var trig;
	trig = Impulse.kr(XLine.kr(0.1, 100, 30));
	Out.ar(out,
		PlayBuf.ar(1, bufnum, BufRateScale.kr(bufnum), trig, 5000, 0)
	)
}).play(s, [\out, 0, \bufnum, b]);


// mouse control of trigger rate and startpos
SynthDef(\help_PlayBuf, { arg out=0, bufnum=0;
	var trig;
	trig = Impulse.kr(MouseY.kr(0.5, 200, 1));
	Out.ar(out,
		PlayBuf.ar(1, bufnum, BufRateScale.kr(bufnum), trig, MouseX.kr(0, BufFrames.kr(bufnum)), 1)
	)
}).play(s, [\out, 0, \bufnum, b]);


// accelerating pitch
SynthDef(\help_PlayBuf, {| out = 0, bufnum = 0 |
	var rate;
	rate = XLine.kr(0.1, 100, 60);
	Out.ar(out,
		PlayBuf.ar(1, bufnum, BufRateScale.kr(bufnum)*rate, 1.0, 0.0, 1.0)
	)
}).play(s, [\out, 0, \bufnum, b]);


// sine wave control of playback rate. negative rate plays backwards
SynthDef(\help_PlayBuf, {| out = 0, bufnum = 0 |
	var rate;
	rate = FSinOsc.kr(XLine.kr(0.2, 8, 30), 0, 3, 0.6);
	Out.ar(out,
		PlayBuf.ar(1, bufnum, BufRateScale.kr(bufnum) * rate, 1, 0, 1)
	)
}).play(s, [\out, 0, \bufnum, b]);


// zig zag around sound
SynthDef(\help_PlayBuf, {| out = 0, bufnum = 0 |
	var rate;
	rate = LFNoise2.kr(XLine.kr(1, 20, 60), 2);
	Out.ar(out,
		PlayBuf.ar(1, bufnum, BufRateScale.kr(bufnum) * rate, 1, 0, 1)
	)
}).play(s, [\out, 0, \bufnum, b]);

b.free;
::

]