afInitFormatParams(3dm)                                afInitFormatParams(3dm)



NAME
     afInitFormatParams - initialize the audio data format in an AFfilesetup
     for a specified audio track via dmParams

SYNOPSIS
     #include <dmedia/dmaudio.h>
     #include <dmedia/audiofile.h>

     DMstatus afInitFormatParams(AFfilesetup setup, int track,
                                 DMparams *params)

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 AFDEFAULTTRACK should be used here for
              now.

     params   a DMparams list, previously created by a call to
              dmParamsCreate(3dm).

RETURN VALUE
     afInitFormatParams() returns DM_SUCCESS on success, otherwise it returns
     DM_FAILURE.

DESCRIPTION
     afInitFormatParams() initializes all parameters associated with the audio
     data in an AFfilesetup structure for an audio track.  It obsoletes the
     individual routines afInitSampleFormat(3dm), afInitChannels(3dm),
     afInitRate(3dm) and afInitCompression(3dm), and
     afInitCompressionParams(3dm).

     The following parameters are defined in dmedia/dm_audio.h and may be set
     via params:

     DMAUDIOFORMAT       Sample format.  Must be DMAUDIOTWOSCOMPLEMENT,
                           DMAUDIOUNSIGNED, DMAUDIOFLOAT, or
                           DMAUDIODOUBLE.

     DMAUDIOWIDTH        Sample width in bits.  For integer sample formats,
                           it must be an integer value between 1 and 32,
                           inclusive.  For formats DMAUDIOFLOAT and
                           DMAUDIODOUBLE, this parameter is ignored.

     DMAUDIOCHANNELS     Channel count.  Integer value greater than or equal
                           to 1.






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afInitFormatParams(3dm)                                afInitFormatParams(3dm)



     DMAUDIORATE         Sampling rate.  Must be a positive, double
                           precision floating point value.

     DMAUDIOCOMPRESSION  Compression type.  Will be DMAUDIOUNCOMPRESSED or
                           one of the supported compression parameter values.
                           In addition, any parameters associated with the
                           compression, such as DMAUDIOBITRATE, should be
                           set here (see afInitCompression(3dm) and
                           afInitCompressionParams(3dm)).

     DMAUDIOPCMMAPSLOPE

     DMAUDIOPCMMAPINTERCEPT

     DMAUDIOPCMMAPMAXCLIP

     DMAUDIOPCMMAPMINCLIP
                           Slope, intercept, minimum and maximum clipping
                           values for PCM mapping (see
                           afGetVirtualPCMMapping(3dm) for a detailed
                           explanation).

     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 either explicitly specify format
     params for this file's tracks which are compatible with that file format,
     or do not set them at all (in which case they will be set to default
     values for the format).

     In the case where the audio track in a file is configured for
     compression, the parameter values for DMAUDIOFORMAT and DMAUDIOWIDTH
     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 ALSO
     afNewFileSetup(3dm), afOpenFile(3dm), afWriteFrames(3dm),
     afSetVirtualSampleFormat(3dm), afGetVirtualSampleFormat(3dm),
     afInitCompression(3dm)









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