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)