samer@34: function ad=sonify(S,D,varargin)
samer@34: % sonify - Sonify sequences of durations and pitches
samer@34: %
samer@34: % sonify :: 
samer@34: %    ([[N]] | seq(real))    ~'sequence of pitches in semitones',
samer@34: %    (natural | seq(real))  ~'sequence of durations',
samer@34: %    options {
samer@34: %       env :: ([[N]]->[[N]])   ~'envelope shaping function',
samer@34: %       transpose :: real /0    ~'add this to all pitches first';
samer@34: %       bpm :: nonneg  /240     ~'number of time units per minute';
samer@34: %
samer@34: %       gen :: { 'sine'      ~'sine wave',
samer@34: %                'square'    ~'frequency-quantised square wave',
samer@34: %                'blsquare'  ~'bandlimited square wave',
samer@34: %                'blsquare2' ~'alternative method',
samer@34: %                'shepard'   ~'Shepard tones'
samer@34: %              } / 'sine'    ~'determines waveform generated';
samer@34: %       betap :: [[2]] /[2,8]  ~'Beta pdf parameters for Shepard tones'
samer@34: %
samer@34: %       fs  :: real    /11025   ~'intended sampling rate';
samer@34: %       buffer :: noneg /0.125  ~'buffer size in seconds, [] means one per note'
samer@34: %    }
samer@34: % -> seq([[1,T]]).
samer@34: 
samer@37: 	opts=options( ...
samer@34: 		'bpm',240,'transpose',0,    ...
samer@34: 		'gen','sine','betap',[2,8], ...
samer@34: 		'fs',11025, 'buffer',0.125, ...
samer@34: 		'env',[],'bl_cutoff',[],  ...
samer@34: 		varargin{:});
samer@34: 
samer@34: 	env=opts.env;
samer@34: 	fm=440/opts.fs;
samer@34: 	dm=60*opts.fs/opts.bpm;
samer@34: 	tr=opts.transpose;
samer@34: 	num2hz=@(n)nan2x(0,fm*2.^((n+tr)/12));
samer@34: 
samer@34: 	if isscalar(D), D=dm*D;
samer@36: 	else D=map(@(d)dm*d,dd(D)); % D=dm*D with optimisation
samer@34: 	end
samer@36: 	C=map(@(n)(n+tr)/12,dd(S)); % chroma values
samer@36: 	F=map(num2hz,dd(S));   % convert to normalised frequencies
samer@34: 
samer@34: 	% cutoff for band-limited waveform generation
samer@34: 	if isempty(opts.bl_cutoff)
samer@34: 		cutoff=0.21+0.2*repeat(normalise01(cumsum(sample(stable(0,1.4,0),[1,1024]),2),2));
samer@34: 	else
samer@34: 		cutoff=opts.bl_cutoff;
samer@34: 	end
samer@34: 
samer@34: 	switch opts.gen
samer@34: 		case 'square'
samer@34: 			% square wave with period quantized to sample period
samer@34: 			Y=blockdata(square,D,0,repeat(0.5),F);
samer@34: 		case 'blsquare'
samer@34: 			% cumsum within each buffer: doesn't drift but makes
samer@34: 			% audible clicks between buffers.
samer@36: 			Y=map(@(t)0.5*cumsum(t),blockdata(bpblit,D,0,cutoff,F));
samer@34: 		case 'blsquare2'
samer@34: 			% this version does cumsum across the sequence to remove 
samer@34: 			% discontinuities but requires high-pass filter to stop drift.
samer@34: 			[fb,fa]=butter(2,0.001,'high');
samer@34: 			Y=filter(0.5*fb,fa,cumsum(blockdata(bpblit,D,0,cutoff,F),2));
samer@34: 		case 'shepard'
samer@34: 			Y=0.04*shepardtone(D,C,opts.betap);
samer@34: 		case 'sine2'
samer@34: 			Y=blockdata(sine,D,0,F)./(F/0.01);
samer@34: 		otherwise
samer@34: 			Y=blockdata(sine,D,0,F);
samer@34: 	end
samer@34: 
samer@34: 	% if supplied apply envelope to shape each note
samer@34: 	if nargin>2 && ~isempty(env),
samer@36: 		ad=map(env,Y);
samer@34: 	else
samer@34: 		ad=Y;
samer@34: 	end
samer@34: 
samer@34: 	% rebuffer to constant size
samer@34: 	if ~isempty(opts.buffer)
samer@36: 		ad=window(ad,ceil(opts.buffer*opts.fs));
samer@34: 	end
samer@34: