From sdif

The SDIF extensions for Matlab come as mex files for Linux, Mac, and Windows XP.

Note that there are two different implementations:

1. the old and simple one based on libSDIF (using only two functions loadsdif and writesdif)
2. the new proper one based on EaSDIF (using functions like Fopensdif, Freadsdif, Fwritesdif, Fclosesdif)

SDIF Matlab FAQ: user-driven documentation

SDIF Matlab Examples

These examples are for the old and simple interface.
See the help files and the scripts that come with the package.

SDIF Matlab Writing with private type definitions and NVTs

function ~[] = testwritesdif(FILENAME, marker_s)

if ~nargin
    FILENAME = 'test_marker_bpm.sdif';
    for l=1:20
        marker_s(l).time = l/pi;
    end
end

% define and write your own types
definition1 = ~['1MTD XBEA { blu, blo }'];
definition2 = ~['1FTD 1MRK { XBEA identifiant; }'];
a = sprintf('%s\n%s\n', definition1, definition2)

writesdif(FILENAME, './~SdifTypes.STYP', a);

% write an NVT
writesdif(0, -1, '1NVT', '1NVT', {'coucou', 'blabla'});

% write some data
for l=1:length(marker_s)
    writesdif(marker_s(l).time, 1, '1MRK', 'XBEA', ~[200 0]);
end

writesdif('close');

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More about writing 1NVTs in Matlab

if you make any sdif file using the Matlab mex functions,
it will contain the following 1NVT accessed through the
loadsdif function.

>> head=loadsdif('blarg.sdif')

head =

numberOfParameters    2
Writtenby    matlabSdifWriter
Version    1

you could write you own NVT frame like

Table{1,1} = 'date written';
Table{1,2} = datestr(now);
Table{2,1} = 'author';
Table{2,2} = 'Noid Blarg';
writesdif('blarg.sdif');
writesdif(0,0,'1NVT','1NVT',Table);
head= loadsdif('blarg.sdif')
head =

numberOfParameters    2
Writtenby    matlabSdifWriter
Version    1
author    Noid Blarg
date written    11-Apr-2006 21:13:13

notice the author is first and the date is second. This is because the NVTs are internally organized in a hash table. What you get depends on the
hash map. The hash function is just summing the int values of the
characters. So the only solution to your problem would be to write more than a
single NVT because each NVT is hashed independently. Thats why you get the
first 3 lines

numberOfParameters    2
Writtenby    matlabSdifWriter
Version    1

always at the same position and always on top of the list. They come from an
independent NVT.

Trying to write multiple NVTs in the same go like

Table1{1,1} = 'date written';
Table1{1,2} = datestr(now);
Table2{1,1} = 'author';
Table2{1,2} = 'Noid Blarg';
writesdif( 0 ,-1 , '1NVT' ,'1NVT',Table1,'1NVT',Table2);

will still be in the same hash table, so the order is psuedo random again.

To get them out in order, you can repeatedly write NVTs as long as you did not write other
frames into the sdif file like

writesdif( 0000 ,32 , '1NVT' ,'1NVT',Table1);
writesdif( -122 ,-1111 , '1NVT' ,'1NVT',Table2);
head= loadsdif('blarg.sdif')
head =

numberOfParameters    2
Writtenby    matlabSdifWriter
Version    1
date written    11-Apr-2006 21:13:13
author    Noid Blarg

Lastly, the StreamID and time must be there, but they can be any float, since they are not evaluated.
The frame type and matrix type must be '1NVT'.

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Partial Tracking example in Matlab
extractraxtosdif.m is a script that uses Dan Ellis' partial tracking mfile extractrax.m to analyze a wav file
and write a 1TRC sdif file from it. I have only gotten it to make good tracks from his clar.wav sample provided, so my
guess is that extractrax.m needs considererable tweaking to work with other sounds.

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