afSetTrackPCMMapping(3dm)                            afSetTrackPCMMapping(3dm)


NAME
     afSetTrackPCMMapping - override the current PCM mapping values associated
     with a given track in an AFfilehandle

SYNOPSIS
     #include <dmedia/audiofile.h>

     int afSetTrackPCMMapping(AFfilehandle file, int track,
                                 double slope, double intercept,
                                 double minclip, double maxclip)

PARAMETER
     file        is an AFfilehandle structure, previously created by a call to
                 afOpenFile(3dm) or its equivalent.

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

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

     slope       is a double precision floating point value which specifies an
                 amplitude scaling factor for the waveform to be associated
                 with track.

     intercept   is a double precision floating point value indicating the
                 audio waveform vertical midpoint ( zero-crossing) value for
                 the audio data associated with track

     minclip     is a double precision floating point value indicating the
                 minimum or most negative audio data sample value to be read.
                 Any value less than this will be set to minclip

     maxclip     is a double precision floating point value indicating the
                 maximum or most positive audio data sample value to be read.
                 Any value greater than this will be set to maxclip

DESCRIPTION
     afSetTrackPCMMapping() allows an application to override the default PCM
     mapping values associated with a track.  This causes the Audio File
     Library to reinterpret the sample data loaded by afReadFrames(3dm)
     according the the new mapping.

CAVEATS
     PCM mapping is only useful for modifying frames as they are read into or
     written out from a buffer via afReadFrames(3dm) or afWriteFrames(3dm).
     None of the currently supported file formats have the capability to store
     this information, even though the actual mapping can and will be applied
     to the frames stored in those files.  Therefor, it is important to be
     careful what values you specify.  In general, all two's complement and
     floating point sample formats are expected to be symmetrical about zero,
     i.e., the intercept will be 0.0 and minclip and maxclip will be negative


     and positive N, where N is some non-zero positive value.

SEE ALSO
     afInitPCMMapping(3dm), afSetVirtualPCMMapping(3dm),
     afGetVirtualPCMMapping(3dm), afReadFrames(3dm)


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