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AFQUERY(3)							    AFQUERY(3)

NAME
       afQuery,	afQueryLong, afQueryDouble, afQueryPointer - query the
       capabilities of the Audio File Library

SYNOPSIS
       #include	<audiofile.h>

       AUpvlist	afQuery	(int querytype,	int arg1, int arg2, int	arg3, int arg4);

       long afQueryLong	(int querytype,	int arg1, int arg2, int	arg3, int arg4);

       double afQueryDouble (int querytype, int	arg1, int arg2,	int arg3,
	   int arg4);

       void *afQueryPointer (int querytype, int	arg1, int arg2,	int arg3,
	   int arg4);

PARAMETERS
       querytype can be	one of the following:

       o    AF_QUERYTYPE_FILEFMT

       o    AF_QUERYTYPE_INST

       o    AF_QUERYTYPE_INSTPARAM

       o    AF_QUERYTYPE_COMPRESSION

       o    AF_QUERYTYPE_COMPRESSIONPARAM

       o    AF_QUERYTYPE_MISC

       o    AF_QUERYTYPE_MARK

       o    AF_QUERYTYPE_LOOP

       arg1, arg2, arg3, and arg4 are integer selectors	whose meaning depends
       upon querytype.

RETURN VALUE
       Upon success, afQuery will return a non-null AUpvlist value. Upon
       failure,	afQuery	will return null while afQueryLong and afQueryDouble
       will return -1 and afQueryPointer will return null.

       Pointers	representing character strings are owned by the	Audio File
       Library and must	not be freed; all other	pointer	values must be freed
       by the caller.

DESCRIPTION
       For AF_QUERYTYPE_FILEFMT, the following selectors are valid values for
       arg1:

       AF_QUERY_LABEL
	   Request a short label string	for the	format (e.g., "aiff").

       AF_QUERY_NAME
	   Request a short name	for the	format (e.g., "MS RIFF WAVE").

       AF_QUERY_DESC
	   Request a descriptive name for the format (e.g., "Audio Interchange
	   File	Format").

       AF_QUERY_IMPLEMENTED
	   Request a boolean value indicating whether the format is
	   implemented for reading and writing in the Audio File Library.

       AF_QUERY_ID_COUNT
	   Request the total number of formats implemented.

       AF_QUERY_IDS
	   Request an integer array of the id token values of all implemented
	   file	formats.

       AF_QUERY_COMPRESSION_TYPES
	   Used	with the selector AF_QUERY_VALUE_COUNT in arg2,	this will
	   return a long integer containing the	number of compression schemes
	   available for use within the	format specified in arg3. Used with
	   selector AF_QUERY_VALUES, it	returns	a pointer to an	integer	array
	   containing the compression id values	of the compression schemes
	   supported by	the format specified in	arg3.

       AF_QUERY_SAMPLE_FORMATS
	   Used	with the selector AF_QUERY_DEFAULT in arg2, this will return
	   the default sample format for the file format specified in arg3.

       AF_QUERY_SAMPLE_SIZES
	   Used	with selector AF_QUERY_DEFAULT in arg2,	this will return the
	   default sample width	for the	file format specified in arg3.

       For AF_QUERYTYPE_INST, the following selectors are valid	for arg1:

       AF_QUERY_SUPPORTED
	   Request a boolean value indicating whether the file format in arg2
	   supports instruments.

       AF_QUERY_MAX_NUMBER
	   Request an integer value indicating the maximum number of
	   instruments supported by the	file format in arg2.

       For AF_QUERYTYPE_INSTPARAM, the following selectors are valid for arg1:

       AF_QUERY_SUPPORTED
	   Request a boolean value indicating whether the file format in arg2
	   supports instrument parameters.

       AF_QUERY_ID_COUNT
	   Request an integer value indicating the number of instrument
	   parameters supported	by the file format in arg2.

       AF_QUERY_IDS
	   Request an integer array containing the instrument parameter	values
	   for the file	format in arg2.

       AF_QUERY_TYPE
	   For the file	format in arg2,	request	the type of the	instrument
	   parameter in	arg3.

       AF_QUERY_NAME
	   For the file	format in arg2,	request	the name of the	instrument
	   parameter in	arg3.

       AF_QUERY_DEFAULT
	   For the file	format in arg2,	request	the default value of the
	   instrument parameter	in arg3.

ERRORS
       afQuery can produce the following errors:

       AF_BAD_QUERYTYPE
	   The query type is unsupported.

       AF_BAD_QUERY
	   The arguments to the	query are bad.

AUTHOR
       Michael Pruett <michael@68k.org>

Audio File Library 0.3.6	  03/06/2013			    AFQUERY(3)

NAME | SYNOPSIS | PARAMETERS | RETURN VALUE | DESCRIPTION | ERRORS | AUTHOR

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