afInitSampleFormat(3dm)                                afInitSampleFormat(3dm)


NAME
     afInitSampleFormat, AFinitsampfmt, afInitByteOrder, afInitChannels,
     afInitRate - initialize the audio data format in an AFfilesetup for a
     specified audio track

SYNOPSIS
     #include <dmedia/audiofile.h>

     void afInitSampleFormat(AFfilesetup setup, int track,
                             int sampfmt, int sampwidth)

     void afInitByteOrder(AFfilesetup setup, int track, int byteorder)

     void afInitChannels(AFfilesetup setup, int track, int channels)

     void afInitRate(AFfilesetup setup, int track, double rate)

PARAMETER
     setup       is an AFfilesetup structure, previously created by a call to
                 afNewFileSetup(3dm).

     track       is an integer which identifies an audio track in setup.

                 Since all currently supported file formats contain only one
                 audio track, the value AF_DEFAULT_TRACK should always be used
                 here.

     sampfmt     an integer constant which denotes a sample format.

     sampwidth   a positive integer value which specifies the number of bits
                 in a sample data point.

     channels    is a positive integer value which indicates the number of
                 interleaved audio channels in the audio track.

     byteorder   is a positive integer token which indicates the byte order of
                 the samples in the audio track.

     rate        is a positive double-precision floating point value which
                 specifies an audio sample rate in Hz to be associated with
                 track.

     afInitSampleFormat() initializes the sample format and width parameters
                 in an AFfilesetup structure for an audio track.

     The following values may be used for sampfmt

     AF_SAMPFMT_TWOSCOMP
          Two's complement samples.  This is currently the only legal value
          for AIFF(4)/AIFF-C and 9-32 bit WAVE(4) format files, and is a legal
          value for all other supported file formats as well.


     AF_SAMPFMT_UNSIGNED
          Unsigned samples.  This is the standard value for 1-8 bit WAVE(4)
          format files.

     AF_SAMPFMT_FLOAT
          32-bit floating point samples.  This may be used with NeXT(4) and
          BICSF(4) format files, as may AF_SAMPFMT_TWOSCOMP.

     AF_SAMPFMT_DOUBLE
          64-bit double-precision floating point samples.  Currently, this may
          only be used with the NeXT(4) format files.

     afInitByteOrder() initializes the byte order (big- or little-endian) of
     the samples in an AFfilesetup structure for an audio track.

     The following values may be used for byteorder

     AF_BYTEORDER_BIGENDIAN
          Big-endian byte order samples.  This is the only legal value for
          AIFF/AIFF-C, NeXT(4), BICSF(4) and Sound Designer II (sd2(4)) files,
          and is the default value.

     AF_BYTEORDER_LITTLEENDIAN
          Little-endian byte order samples.  This is the standard value for
          WAVE(4) format files.

     afInitChannels() initializes the number of interleaved channels
          in an AFfilesetup structure for an audio track.  Legal values vary
          depending on the file format (see afInitFileFormat(3dm)).

     afInitRate() initializes the sample rate in Hz in an AFfilesetup
     structure for an audio track.  Most file formats have no restrictions on
     sample rate values, the exception being the NeXT(4) format, which
     requires integer values only.

     When a file is opened for writing by passing setup to afOpenFile(3dm),
     the track will be configured to store data according to the data format,
     width, number of channels, or sample rate specified.

CAVEATS
     The Audio File Library will continue to support additional file formats.
     The ability of these file formats to store data of various sample formats
     will vary.  If you are choosing a file format other than the default
     format, you should make sure that you explicitly specify a sample format
     for this file's tracks which is compatible with that file format.  See
     afGetSampleFormat(3dm) for important information about handling this
     situation.

     In the case where the audio track in a file is configured for
     compression, sampfmt and sampwidth should match the data format specified
     by the compression algorithm.  For example, the software G.722 compressor
     expects to encode 16-bit two's complement linear PCM input data. In


     addition, many compression formats have restrictions on sample rate
     and/or channel count as well.  See afInitCompression(3dm) for more
     information.

SEE ALSO
     afNewFileSetup(3dm), afOpenFile(3dm), afWriteFrames(3dm),
     afSetVirtualSampleFormat(3dm), afGetVirtualSampleFormat(3dm),
     afInitCompression(3dm)


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