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CentOS 7.0 - man page for afquery (centos section 3)

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)


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