AFsetNHpar(3tsp)

Routine
int AFsetNHpar (const char String[])

Purpose
Set defaults for headerless audio files from a string specification

Description
This routine sets or gets default audio file data parameters. These parameters are used for files with unrecognized (non-standard) headers or files with no headers (raw audio files). This routine must be called before opening the file with AFopenRead. The parameters for AFsetNHpar are determined from an input string which consists of a list of parameters separated by commas. The form of the list is
  "Format, Start, Sfreq, Swapb, Nchan, ScaleF"
Format: File data format
 "undefined" - Headerless files will be rejected
 "mu-law8"   - 8-bit mu-law data
 "A-law8"    - 8-bit A-law data
 "unsigned8" - offset-binary 8-bit integer data
 "integer8"  - two's-complement 8-bit integer data
 "integer16" - two's-complement 16-bit integer data
 "integer24" - two's-complement 24-bit integer data
 "integer32" - two's-complement 32-bit integer data
 "float32"   - 32-bit floating-point data
 "float64"   - 64-bit floating-point data
 "text"      - text data
Start: byte offset to the start of data (integer value)
Sfreq: sampling frequency in Hz (floating-point number)
Swapb: Data byte swap parameter
 "native" - no byte swapping
 "little-endian" - file data is in little-endian byte order and
    will be swapped if the current host uses big-endian byte order
 "big-endian" - data is in big-endian byte order and will be
    swapped swapped if the current host uses little-endian byte
    order
 "swap" - swap the data bytes
Nchan: number of channels
The data consists of interleaved samples from Nchan channels
ScaleF: Scale factor
Scale factor applied to the data from the file
The default values correspond to the following string
  "undefined, 0, 8000., native, 1, 1.0"

Leading and trailing white-space (as defined by isspace) is removed from each item. In the input string, any of the parameters may be omitted, in which case whatever value has been previously set remains in effect for that parameter. The string ",512, 10000." would set the Start and Sfreq parameters and leave the other parameters undisturbed.

If the input string contains has a leading '$', the string is assumed to specify the name of an environment variable after the '$'. This routine uses the value of this environment variable to determine the parameters. If this routine is called as AFsetNHpar("$AF_NOHEADER"), this routine would look for the parameter string in environment variable AF_NOHEADER.

Parameters
<- int AFsetNHpar
Error flag, zero for no error
 -> const char String[]
String containing the list of parameters for headerless files or the name of an environment variable (with a leading $)

Author / revision
P. Kabal Copyright (C) 1999 / Revision 1.45 1999/06/04

See Also
AFopenRead, AFsp