dawn@0: function i = sf_format(i)
dawn@0: % i=sf_format(i) - try to guess file format from 
dawn@0: % magic words or file suffix
dawn@0: 
dawn@0: % Alain de Cheveigné, CNRS/Ircam, 2002.
dawn@0: % Copyright (c) 2002 Centre National de la Recherche Scientifique.
dawn@0: %
dawn@0: % Permission to use, copy, modify, and distribute this software without 
dawn@0: % fee is hereby granted FOR RESEARCH PURPOSES only, provided that this
dawn@0: % copyright notice appears in all copies and in all supporting 
dawn@0: % documentation, and that the software is not redistributed for any 
dawn@0: % fee (except for a nominal shipping charge). 
dawn@0: %
dawn@0: % For any other uses of this software, in original or modified form, 
dawn@0: % including but not limited to consulting, production or distribution
dawn@0: % in whole or in part, specific prior permission must be obtained from CNRS.
dawn@0: % Algorithms implemented by this software may be claimed by patents owned 
dawn@0: % by CNRS, France Telecom, Ircam or others.
dawn@0: %
dawn@0: % The CNRS makes no representations about the suitability of this 
dawn@0: % software for any purpose.  It is provided "as is" without express
dawn@0: % or implied warranty.  Beware of the bugs.
dawn@0: 
dawn@0: if ~nargin; error('no argument'); end
dawn@0: if ~isa(i, 'struct')
dawn@0: 	i.fname=i;
dawn@0: 	i=sf_format(i);
dawn@0: 	return
dawn@0: end
dawn@0: if ~isfield(i, 'fname'); error('no fname field'); end
dawn@0: 
dawn@0: if isa(i.fname, 'double')
dawn@0: 	i.format = 'matrix'; return
dawn@0: end
dawn@0: 
dawn@0: if isa(i.fname, 'char')  
dawn@0: 	disp(['guessing format of ', i.fname, '...']);
dawn@0: else 
dawn@0: 	disp('guessing format...');
dawn@0: end
dawn@0: 
dawn@0: % Well-known file extensions
dawn@0: a = findstr('.', i.fname);
dawn@0: if a
dawn@0: 	suff = i.fname( a(size(a,2))+1 : size(i.fname,2));
dawn@0: 	suff = lower(suff);
dawn@0: 	switch suff
dawn@0: 	case {'short', 'long', 'float', 'double', 'ascii', 'mat'}
dawn@0: 		i.format = suff;
dawn@0: 		return
dawn@0: % the following are commented out to exercise header magic
dawn@0: % 	case {'aiff'}
dawn@0: % 		i.format = 'AIFF';
dawn@0: % 		return
dawn@0: % 	case {'aifc'}
dawn@0: % 		i.format = 'AIFC';
dawn@0: % 		return
dawn@0: % 	case 'wav'
dawn@0: % 		i.format = 'WAV';
dawn@0: % 		return
dawn@0: % 	case 'au'
dawn@0: % 		i.format = 'AU';
dawn@0: % 	case 'sdif'
dawn@0: % 		i.format = 'sdif';
dawn@0: 	% others ?
dawn@0: 	end
dawn@0: end
dawn@0: 
dawn@0: % close file if open
dawn@0: if exist('i.fd') & fopen(i.fd)
dawn@0: 	fclose(i.fd);
dawn@0: end
dawn@0: 
dawn@0: 
dawn@0: % open little-endian, check for .wav magic
dawn@0: [i.fd, msg] = fopen(i.fname, 'r', 'l');
dawn@0: if i.fd == -1
dawn@0: 	error(['could not open: >', i.fname, '<']);
dawn@0: 	if ~isempty(msg)
dawn@0: 		error(msg);
dawn@0: 	end
dawn@0: end
dawn@0: 
dawn@0: % file size in bytes
dawn@0: if (-1 == fseek(i.fd, 0, 1)) ; error ('fseek failed');  end;	
dawn@0: i.nbytes = ftell(i.fd);
dawn@0: if i.nbytes == 0 & strcmp(computer, 'MAC2')
dawn@0:     disp('file is empty: perhaps its a macintosh SND resource?');
dawn@0: 	i.format = 'MACSND';	% macintosh sound resource (maybe...)
dawn@0: 	return
dawn@0: end
dawn@0: if i.nbytes < 4; error('file is less than 4 bytes long'); end;	
dawn@0: fseek(i.fd, 0, -1);			
dawn@0: magic = char(fread(i.fd, 4, 'uchar'))';
dawn@0: if strcmp(magic, 'RIFF') & i.nbytes >=12
dawn@0: 	dummy = fread(i.fd, 1, 'ulong');	% chunk size
dawn@0: 	magic = char(fread(i.fd, 4, 'uchar'))';
dawn@0: 	if strcmp(magic, 'WAVE');
dawn@0: 		i.format='WAV';
dawn@0: 		return
dawn@0: 	end
dawn@0: end
dawn@0: 
dawn@0: % reopen for standard binary, look for magic
dawn@0: fclose(i.fd);
dawn@0: i.fd = fopen(i.fname, 'r');
dawn@0: if (-1 == fseek(i.fd, 0, 1)) ; error ('fseek failed');  end;	
dawn@0: i.nbytes = ftell(i.fd);
dawn@0: fseek(i.fd, 0, -1);	
dawn@0: % magic strings?
dawn@0: magic = char(fread(i.fd, 4, 'uchar'))';
dawn@0: switch magic
dawn@0: case '.snd'
dawn@0: 	i.format = 'AU';
dawn@0: 	return;	
dawn@0: case 'FORM'
dawn@0: 	fseek(i.fd, 8, -1);
dawn@0: 	i.format = char(fread(i.fd, 4, 'uchar'))';
dawn@0: 	if ~strcmp(i.format, 'AIFF') & ~strcmp(char(i.format),'AIFC')
dawn@0: 		error (['expected AIFF or AIFC, found ' i.format]); 
dawn@0: 	end;
dawn@0: 	return;
dawn@0: case 'NIST'
dawn@0: 	fseek(i.fd, 0, -1);
dawn@0: 	line = fscanf(i.fd, '%s' , 1);
dawn@0: 	if ~strcmp(line, 'NIST_1A'); 
dawn@0: 		error(['expected NIST_1A, found ', magic]); 
dawn@0: 	end;
dawn@0: 	disp(i.format);	
dawn@0: 	return;
dawn@0: case 'SDIF'
dawn@0: 	i.format = 'SDIF';
dawn@0: 	return;
dawn@0: end
dawn@0: % wff magic number?
dawn@0: wff_magic =  195894762;
dawn@0: fseek(i.fd, 0, -1);
dawn@0: magic = fread(i.fd, 1, 'long');
dawn@0: if magic == wff_magic
dawn@0: 	i.format = 'wff';	% Nottingham IHR wff format
dawn@0: 	return
dawn@0: end
dawn@0: % ESPS?
dawn@0: esps_min_size = 333; esps_magic = 27162;
dawn@0: if i.nbytes > esps_min_size	
dawn@0: 	fseek(i.fd, 16, -1);
dawn@0: 	magic = fread(i.fd, 1, 'uint');
dawn@0: 	if magic == esps_magic
dawn@0: 		i.format = 'ESPS';
dawn@0: 		return
dawn@0: 	end
dawn@0: end
dawn@0: 
dawn@0: 
dawn@0: % Magic didn't succeed, try to determine type based on file name
dawn@0: a = findstr('.', i.fname);
dawn@0: if a
dawn@0: 	suff = i.fname( a(size(a,2))+1 : size(i.fname,2));
dawn@0: 	switch suff
dawn@0: 	case 's'
dawn@0: 		i.format = 'short';
dawn@0: 		return
dawn@0: 	case 'f'
dawn@0: 		i.format = 'float';
dawn@0: 		return
dawn@0: 		% others ?
dawn@0: 	end
dawn@0: end
dawn@0: 
dawn@0: 
dawn@0: % Ascii formats
dawn@0: fclose(i.fd);
dawn@0: i.fd = fopen(i.fname, 'rt');
dawn@0: line = fscanf(i.fd, '%s' , 1);
dawn@0: if strcmp(line, '|WAVE'); 
dawn@0: 	i.format = 'iwave';			% Nottingham IHR |WAVE format
dawn@0: 	return;
dawn@0: end
dawn@0: 
dawn@0: % plain ascii ?
dawn@0: limit = 2048;	% test only this many bytes
dawn@0: hunk = char(fread(i.fd, min(limit, i.nbytes)));
dawn@0: chars = unique(hunk);
dawn@0: if isempty(setdiff(chars, [9, 10, 13, ...
dawn@0: 	double(' abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890+-_.,:;')]))
dawn@0: 	% ascii
dawn@0: 	if ~isempty(setdiff(chars, [9, 10, 13, double(' 1234567890eE+-.,')]))
dawn@0: 		% not just numerical: try removing first line
dawn@0: 		fseek(i.fd, 0, -1);
dawn@0: 		line = fgets(i.fd);
dawn@0: 		if -1 == line; return ; end	% line too long 
dawn@0: 		i.bytes_to_data = ftell(i.fd);
dawn@0: 		hunk = char(fread(i.fd, min(limit, i.nbytes-ftell(i.fd))));
dawn@0: 		chars = unique(hunk);
dawn@0: 		warning('skipping first line of what seems like an ascii file');
dawn@0: 	end 
dawn@0: 	if isempty(setdiff(chars, [9, 10, 13, double(' 1234567890eE+-.')]))
dawn@0: 		i.format = 'ascii';
dawn@0: 		return
dawn@0: 	end
dawn@0: 	if isempty(setdiff(chars, [9, 10, 13, double(' 1234567890eE+-.,')]))
dawn@0: 		w.format = 'csv';
dawn@0: 		return
dawn@0: 	end
dawn@0: end
dawn@0: 
dawn@0: % Default
dawn@0: if i.nbytes == 2 * round(i.nbytes/2);	% even number of bytes
dawn@0: 	i.format = 'short';
dawn@0: else
dawn@0: 	i.format = 'uchar';
dawn@0: end
dawn@0: