samer@0: % sndstream - file reader implementation using samer.audio.alt.FileSource
samer@0: %
samer@0: % sndstream ::
samer@0: %    (unit -> (AudioInputStream, unit -> unit)) ~'function to open stream',
samer@0: %    (unit -> string) ~'function to create character representation',
samer@0: %    options {
samer@0: %       channels :: natural/nan ~'desired number of channels';
samer@0: %       rate     :: nonneg/nan ~'desired sampling rate';
samer@0: %       bits     :: natural/16 ~'desired bits per sample';
samer@0: %    }
samer@0: % -> signal(C,R).
samer@0: %
samer@0: % If channels or rate are not nan, audio format will be converted to match.
samer@0: % If either of them are nan, the corresponding value from the audio file will
samer@0: % be left unchanged.
samer@0: 
samer@0: classdef sndstream < signal
samer@0: 	properties (GetAccess=private, SetAccess=immutable)
samer@0: 		streamfn
samer@0: 		stringfn
samer@0: 		format
samer@0: 	end
samer@0: 	methods
samer@0: 		function s=sndstream(streamfn,varargin)
samer@0: 			opts=prefs('channels',nan,'rate',nan,'bits',16, ...
samer@0: 						  'stringfn',@()sprintf('sndstream(%s)',tostring(streamfn)), ...
samer@0: 						  varargin{:});
samer@0: 
samer@0: 			if any(isnan([opts.channels,opts.rate,opts.bits]))
samer@0: 				fmt=peek(streamfn);
samer@0: 				if isnan(opts.channels), opts.channels=fmt.getChannels(); end
samer@0: 				if isnan(opts.rate), opts.rate=fmt.getSampleRate(); end
samer@0: 				if isnan(opts.bits), opts.bits=fmt.getSampleSizeInBits(); end
samer@0: 			end
samer@0: 			if opts.bits<0
samer@0: 				error('Cannot determine bits per sample');
samer@0: 			end
samer@0: 			
samer@0: 			s.streamfn=streamfn;
samer@0: 			s.stringfn=opts.stringfn;
samer@0: 			s.format=audio_format(opts.channels,opts.rate,opts.bits);
samer@0: 		end
samer@0: 
samer@0: 		function s=tostring(sig), s=sig.stringfn(); end
samer@0: 		function c=channels(s), c=s.format.getChannels(); end
samer@0: 		function r=rate(s), r=s.format.getSampleRate(); end
samer@0: 
samer@0: 		function s=construct(sig)
samer@0: 			[str,cleanup]=sig.streamfn(false);
samer@0: 			src=samer.audio.alt.StreamSource(str,sig.format);
samer@0: 			ref=disposables('reg',src);
samer@0: 			s.start = @()src.start();
samer@0: 			s.stop = @()src.stop();
samer@0: 			s.reader = @reader;
samer@0: 			s.dispose = @dispose;
samer@0: 
samer@0: 			function r=reader(n)
samer@0: 				ch=src.getFormat.getChannels();
samer@0: 				rdr=src.reader(n*ch);
samer@0: 				r=@next;
samer@0: 				function [x,rem]=next
samer@0: 					x=reshape(rdr.next(),ch,n);
samer@0: 					rem=rdr.unread()/ch;
samer@0: 				end
samer@0: 			end
samer@0: 			function dispose
samer@0: 				disposables('dereg',ref);
samer@0: 				src.dispose();
samer@0: 				cleanup();
samer@0: 			end
samer@0: 		end
samer@0: 	end
samer@0: end
samer@0: 
samer@0: function fmt=peek(streamfn)
samer@0: 	[str,cleanup]=streamfn(true);
samer@0: 	f1=str.getFormat();
samer@0: 	str.close(); cleanup();
samer@0: 	ss=f1.getSampleSizeInBits();
samer@0: 	if ss<0, ss=16; end
samer@0: 	fmt=audio_format(f1.getChannels(),f1.getSampleRate(),ss);
samer@0: end