AFILE *AFopnWrite(const char Fname, enum AF_FTW_T FtypeW,
enum AF_FD_T Format, long int Nchan, double Sfreq,
Open an audio file for writing
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.
By default, information records consisting, for instance, the date and the program creating the file (see UTsetProg) are written to the audio file header or trailer. The routine AFsetInfo can be called before calling this routine to specify additional information to be written to the file.
This routine can write AU audio files, AIFF, AIFF-C files, WAVE files, text audio files, and headerless audio files.
For the fixed point file data representations, input values in the range [-1, +1) ([-0.5, +0.5) for 8-bit data) will be converted without clipping. The scaling factor shown below is applied to the data before they are written to the file.
data format scaling factor file data values 8-bit A-law 32,768 [-32,256, +32,256] 8-bit mu-law 32,768 [-32,124, +32,124] 8-bit integer 256 [-128, 127] 16-bit integer 32,768 [-32,768, +32,767] 24-bit integer 8,388,608 [-8,388,608, +8,388,607] 32-bit integer 2,147,483,648 [-2,147,483,648, 2,147,483,647]
For files containing floating-point data, values are scaled by unity.
The file type codes (defined in AFpar.h) accepted are
FTW_AU - AU audio file FTW_WAVE - WAVE audio file, upgraded to WAVE-ex if appropriate FTW_WAVE_EX - WAVE audio file (extensible format) FTW_WAVE_NOEX - WAVE audio file, do not upgrade to WAVE-ex FTW_AIFF - AIFF audio file FTW_AIFF_C - AIFF-C audio file FTW_AIFF_C_SOWT - AIFF-C audio file (PCM, byte swapped) FTW_NH_NATIVE - noheader file, native byte order FTW_NH_SWAP - noheader file, swap byte order FTW_NH_EL - noheader file, little-endian data FTW_NH_EB - noheader file, big-endian data FTW_TEXT - Text audio file (with header)
The data format codes (defined in AFpar.h) accepted are
FD_ALAW8 - A-law 8-bit FD_MULAW8 - mu-law 8-bit FD_MULAWR8 - bit-reversed mu-law 8-bit FD_UINT8 - offset binary integer 8-bit FD_INT8 - integer 8-bit FD_INT16 - integer 16-bit FD_INT24 - integer 24-bit FD_INT32 - integer 32-bit FD_FLOAT32 - float 32-bit FD_FLOAT64 - float 64-bit FD_TEXT16 - text data scaled as 16-bit integers FD_TEXT - text data
The data types accepted by the different file types are as follows.
AU audio files: mu-law, A-law, 8/16/24/32-bit integer, 32/64-bit float WAVE files: mu-law, A-law, offset-binary 8-bit, 16/24/32-bit integer, 32/64-bit float AIFF-C sound files: mu-law, A-law, 8/16/24/32-bit integer, 32/64-bit float AIFF and AIFF-C/sowt sound files: 8/16/24/32-bit integer Text audio files: text data Headerless files: all data formats
P. Kabal / Revision 1.34 2023-03-14