afQueryLong (3) - Linux Manuals
afQueryLong: query the capabilities of the Audio File Library
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:
-
•
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 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 [at] 68k.org>