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AFQUERY(3)							      AFQUERY(3)

NAME
     afQuery,  afQueryLong,  afQueryDouble, afQueryPointer - query the capabili-
     ties 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:

     *	  AF_QUERYTYPE_FILEFMT

     *	  AF_QUERYTYPE_INST

     *	  AF_QUERYTYPE_INSTPARAM

     *	  AF_QUERYTYPE_COMPRESSION

     *	  AF_QUERYTYPE_COMPRESSIONPARAM

     *	  AF_QUERYTYPE_MISC

     *	  AF_QUERYTYPE_MARK

     *	  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 de-
	 fault 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 sup-
	 ports 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 sup-
	 ports 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 parame-
	 ter in arg3.

     AF_QUERY_NAME
	 For the file format in arg2, request the name of the instrument parame-
	 ter in arg3.

     AF_QUERY_DEFAULT
	 For  the  file format in arg2, request the default value of the instru-
	 ment 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)

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=afQuery&sektion=3&manpath=FreeBSD+Ports+15.1.quarterly>

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