sd2(4)									sd2(4)

NAME    [Toc]    [Back]

     sounddesigner2, sd2, sdII - Sound Designer	II Audio File Format

SYNOPSIS    [Toc]    [Back]

     #include <dmedia/audiofile.h>

DESCRIPTION    [Toc]    [Back]

     The Audio File Library currently supports eight of	the commonly found
     audio file	formats, i.e., is able to recognize, read, and write sample
     data and header information to and	from files in these formats.  It is
     important not to confuse sample or	audio data formats with	file formats.
     The former	refers to the bit-wise organization of the sound samples in
     the file, i.e., whether the format	is 8-bit integer or 16-bit unsigned,
     etc.  Audio file format refers to the structure of	the audio file header,
     the chunk of on-disk data which preceeds the samples and which provides
     information about the file	to the audio program.  A single	audio file
     format may	support	a large	variety	of sample formats.

     The Sound Designer	II Audio File Format (sd2) was created by DigiDesign,
     Inc., as a	replacement for	their earier Sound Designer I format (not
     supported by the Audio File Library). Because it was developed for	the
     Apple MacIntosh file system, this file format differs from	all other
     currently supported audio file formats in that its	representation on a
     UNIX file system varies depending on how the file is made available.  All
     involve a data fork or file containing the	binary sample data and a
     resource fork or file containing all information about the	file and its
     format.  Three representations are	supported:

     Apple Single Format    [Toc]    [Back]
	  Resource and data forks are combined into a single file

     Apple Double Format    [Toc]    [Back]
	  Resource and data forks put into separate files;  the	data fork file
	  carries the actual file name,	and the	resource fork file has (in
	  most cases) a	percent	(%) character prepended	to the filename

     Xinet (IRISShare) Format    [Toc]    [Back]
	  Resource and data forks put into separate files;  the	data fork file
	  carries the actual file name,	and the	resource fork file is located
	  in a subdirectory named ".HSResource".  This is always subdirectory
	  of the directory containing the data fork file.  In addition,	a
	  third	file named .HSAncillary	contains additional "ancillary data"
	  about	every Apple file in the	current	directory.  This file stores
	  information about the	file type and file creation dates, among other
	  things.

DATA FORMAT SPECIFICATIONS    [Toc]    [Back]

     Sample Formats:
	  Two's	complement integer only






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     Sample Widths:
	  16-bit only

     Byte Orders:
	  Bigendian only

     Channel Counts:
	  1 and	2 channels only

     Compression Formats:
	  None supported, and none in common usage

FILE FORMAT SPECIFICATIONS    [Toc]    [Back]

     Sound Designer II files can contain large amounts of additional
     information.

     Instrument	Configurations:
	  Maximum of 1 allowed.	 Any number of loops per inst.	Insts are
	  stored as a set of loops with	no associated instparams.  Loops are
	  stored as a starting frame, an ending	frame, a loop sense (forward
	  or forward-backward) plus an index (set incrementally	from 0 up) and
	  a channel (currently set to 0).

     Markers:
	  Any number of	markers	is allowed.  Unlike AIFF(3dm) and WAVE(3dm)
	  files, there is no direct association	between	markers	and loops.  An
	  application may choose to specify loop start and end points via the
	  traditional AIFF-style method	using mark id's	(afSetLoopStart(3dm),
	  etc.)	or via the newer afSetLoopStartFrame(3dm) and related
	  routines.  In	the former case, both the loops	and the	markers	will
	  be written out to the	header;	in the latter case, only the loops
	  will be written out (unless other markers have been created).

     In	addition, it is	possible to associate both a name string and a comment
     string with each marker.  The routines afInitMarkName(3dm)	and
     afInitMarkComment(3dm) will do this.  Both	the name and comment will be
     written into a text buffer	with the format	<marker	name>: <marker
     comment>.

     Miscellaneous Chunks:

	       AF_MISC_COMMENT	       text comment string

CAVEATS    [Toc]    [Back]

     Due to the	nature of the file structure as	described above, the Audio
     File Library must take extra steps	to identify and	read this format.
     Specifically, it must have	the full pathname of the file available	for
     the call to identify the file (if used) and the call to open it.  The
     functions afIdentifyNamedFDafOpenFile(3dm) call.





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sd2(4)									sd2(4)



     The current version of the	AF can read Sound Designer II files in any of
     the above-three file representations, but all newly created files will be
     written in	Xinet representation only.  Future releases of the AF may
     allow a choice.

SEE ALSO    [Toc]    [Back]

     afInitFileFormat(3dm), afGetFileFormat(3dm), afIntro(3dm),
     afIdentifyNamedFD(3dm)


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