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)