AFopenWrite

Routine

AFILE *AFopenWrite (const char Fname[], int Fformat, long int Nchan, double Sfreq, FILE *fpout)

Purpose

Open an audio file for writing

Description

This routine opens an audio file for writing. This routine sets up the audio file parameters to write data of the given format to the audio file. After writing data to the file, the routine AFclose should be called to update the file header information and close the file.

This routine can write AFsp (Sun) audio files, RIFF WAVE files and headerless audio files.

AFsp audio file:: The AFsp audio file format uses a file header which is compatible with a Sun audio file header. By default, information consisting of the date, the user and the program creating the file is written to the header. The routine AFsetHInfo can be called before calling this routine to specify additional information to be written to the header. Any such additional header information is reset to null by this routine. 8-bit mu-law, 8-bit A-law, 8-bit integer, 16-bit integer, and 32-bit IEEE floating-point data formats are supported.
RIFF WAVE file:: 8-bit mu-law, 8-bit A-law, 8-bit integer, and 16-bit integer data formats are supported.
AIFF-C file:: 8-bit mu-law, 8-bit A-law, 8-bit integer, and 16-bit integer data formats are supported.
Headerless file:: 8-bit mu-law, 8-bit A-law, offset-binary 8-bit integer, 8-bit integer, 16-bit integer, 32-bit floating-point, and text data formats are supported. A text format file has the data in character form, one value to a line.

For the fixed point file data representations, input values in the following ranges will be converted without clipping.

   data format       allowed values
  8-bit mu-law   - [ -32636, +32636 ]
  8-bit A-law    - [ -32768, +32768 ]
  8-bit integer  - [ -16384, -16383 ]
  16-bit integer - [ -32768, +32767 ]

For AFsp files containing floating-point data, values are scaled by 1/32768 before being written to the file. For data values between [ -32768, +32768 ], the file data will lie in the range [ -1, +1]. For headerless files of any data format, the values are written scaled by unity.

Parameters

<- AFILE *AFopenWrite

Audio file pointer for the audio file

-> const char Fname[]

Character string specifying the file name

-> int Fformat

Audio file format code, evaluated as the sum of a data format code and a file type,

  Fformat = Dformat + Ftype

For Ftype equal to zero, the file will have the standard AFsp audio file header. The Ftype flag allows for other file types as described below. Note that not all data formats are allowed for all file types. Dformat: data format

  FD_MULAW8  = 1,  mu-law 8-bit data
  FD_ALAW8   = 2,  A-law 8-bit data
  FD_UINT8   = 3,  offset-binary 8-bit integer data
  FD_INT8    = 4,  two's-complement 8-bit integer data
  FD_INT16   = 5,  two's-complement 16-bit integer data
  FD_FLOAT32 = 6,  32-bit floating-point data
  FD_TEXT    = 7,  text data

Ftype: file type

  FW_AFsp = FW_SUN     = 0, AFsp (Sun) audio file
  FW_WAVE              = 256, RIFF WAVE file
  FW_AIFF_C            = 512, AIFF-C audio file
  FW_NH_EB             = 768, Headerless file (big-endian byte order)
  FW_NH_EL             = 1024, Headerless file (little-endian byte order)
  FW_NH = FW_NH_NATIVE = 1280, Headerless file (native byte order)
  FW_NH_SWAP           = 1536, Headerless file (swapped byte order)

-> long int Nchan

Number of channels

-> double Sfreq

Sampling frequency

-> FILE *fpout

File pointer for printing audio file information. If fpout is not NULL, information about the audio file is printed on the stream selected by fpout.

Author / revision