AFopenRead

Routine

AFILE *AFopenRead (const char Fname[], long int *Nsamp, long int *Nchan, float *Sfreq, FILE *fpout)

Purpose

Open an audio file for reading

Description

This routine opens an audio file for reading. If unsuccessful, the program is terminated. The companion routine AFreadData reads data from the file. Routine AFclose should be used to close the file.

This routine reads the audio file header and optionally prints the header information. Several file header formats are supported. For files with no header or unrecognized headers, the file format can be declared by calling routine AFsetNH.

Sun (AFsp) audio file:: 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:: 8-bit mu-law, 8-bit A-law, offset-binary 8-bit integer, and 16-bit integer data formats are supported.
AIFF or AIFF-C audio file:: 8-bit mu-law, 8-bit A-law, 8-bit integer, and 16-bit integer data formats are supported.
NIST SPHERE audio file:: 8-bit mu-law and 16-bit integer data formats are supported.
IRCAM soundfile:: 8-bit mu-law, 8-bit A-law, 16-bit integer, and 32-bit floating-point data formats are supported.
ESPS sampled data feature file:: 16-bit integer and 32-bit IEEE floating-point data formats are supported.
SPPACK sampled data file:: 8-bit mu-law, 8-bit A-law and 16-bit integer data formats are supported.
INRS-Telecommunications audio file:: 16-bit integer format is supported.
Text audio file:: Data in character format (usually representing 16-bit integer values).
Headerless audio file:: Data format is specified by calling routine AFsetNH.

For the fixed point file data representations, read operations return data values as follows.

   format            returned values
  8-bit mu-law   - [ -32124, +32124 ]
  8-bit A-law    - [ -32256, +32256 ]
  8-bit integer  - [ -16384, -16383 ]
  16-bit integer - [ -32768, +32767 ]

For Sun (AFsp) files, floating-point data in the file are scaled by 32768. For file data values between -1 and +1, the returned values will be in the range [ -32768, +32768 ]. For ESPS sample data feature files and IRCAM soundfiles, floating-point values in the file are returned with unity scaling.

Parameters

<- AFILE *AFopenRead: Audio file pointer for the audio file
-> const char Fname[]: Character string specifying the file name
<- long int *Nsamp: Total number of samples in the file (all channels)
<- long int *Nchan: Number of channels
<- float *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