diff dsp/synth/sonify.m @ 34:c75bb62b90a9

Imported audio synthesis tools.

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dsp/synth/sonify.m	Sun Jan 20 19:05:05 2013 +0000
@@ -0,0 +1,83 @@
+function ad=sonify(S,D,varargin)
+% sonify - Sonify sequences of durations and pitches
+%
+% sonify :: 
+%    ([[N]] | seq(real))    ~'sequence of pitches in semitones',
+%    (natural | seq(real))  ~'sequence of durations',
+%    options {
+%       env :: ([[N]]->[[N]])   ~'envelope shaping function',
+%       transpose :: real /0    ~'add this to all pitches first';
+%       bpm :: nonneg  /240     ~'number of time units per minute';
+%
+%       gen :: { 'sine'      ~'sine wave',
+%                'square'    ~'frequency-quantised square wave',
+%                'blsquare'  ~'bandlimited square wave',
+%                'blsquare2' ~'alternative method',
+%                'shepard'   ~'Shepard tones'
+%              } / 'sine'    ~'determines waveform generated';
+%       betap :: [[2]] /[2,8]  ~'Beta pdf parameters for Shepard tones'
+%
+%       fs  :: real    /11025   ~'intended sampling rate';
+%       buffer :: noneg /0.125  ~'buffer size in seconds, [] means one per note'
+%    }
+% -> seq([[1,T]]).
+
+	opts=prefs( ...
+		'bpm',240,'transpose',0,    ...
+		'gen','sine','betap',[2,8], ...
+		'fs',11025, 'buffer',0.125, ...
+		'env',[],'bl_cutoff',[],  ...
+		varargin{:});
+
+	env=opts.env;
+	fm=440/opts.fs;
+	dm=60*opts.fs/opts.bpm;
+	tr=opts.transpose;
+	num2hz=@(n)nan2x(0,fm*2.^((n+tr)/12));
+
+	if isscalar(D), D=dm*D;
+	else D=fndata(@(d)dm*d,dd(D),'compose',1); % D=dm*D with optimisation
+	end
+	C=fndata(@(n)(n+tr)/12,dd(S),'compose',1); % chroma values
+	F=fndata(num2hz,dd(S),'compose',1);   % convert to normalised frequencies
+
+	% cutoff for band-limited waveform generation
+	if isempty(opts.bl_cutoff)
+		cutoff=0.21+0.2*repeat(normalise01(cumsum(sample(stable(0,1.4,0),[1,1024]),2),2));
+	else
+		cutoff=opts.bl_cutoff;
+	end
+
+	switch opts.gen
+		case 'square'
+			% square wave with period quantized to sample period
+			Y=blockdata(square,D,0,repeat(0.5),F);
+		case 'blsquare'
+			% cumsum within each buffer: doesn't drift but makes
+			% audible clicks between buffers.
+			Y=fndata(@(t)0.5*cumsum(t),blockdata(bpblit,D,0,cutoff,F));
+		case 'blsquare2'
+			% this version does cumsum across the sequence to remove 
+			% discontinuities but requires high-pass filter to stop drift.
+			[fb,fa]=butter(2,0.001,'high');
+			Y=filter(0.5*fb,fa,cumsum(blockdata(bpblit,D,0,cutoff,F),2));
+		case 'shepard'
+			Y=0.04*shepardtone(D,C,opts.betap);
+		case 'sine2'
+			Y=blockdata(sine,D,0,F)./(F/0.01);
+		otherwise
+			Y=blockdata(sine,D,0,F);
+	end
+
+	% if supplied apply envelope to shape each note
+	if nargin>2 && ~isempty(env),
+		ad=fndata(env,Y,'sizecheck',1);
+	else
+		ad=Y;
+	end
+
+	% rebuffer to constant size
+	if ~isempty(opts.buffer)
+		ad=windowdata(ad,ceil(opts.buffer*opts.fs));
+	end
+