afGetFormatParams(3dm)					afGetFormatParams(3dm)

NAME    [Toc]    [Back]

     afGetFormatParams - get the audio data format in an AFfilehandle for a
     specified audio track via dmParams

SYNOPSIS    [Toc]    [Back]

     #include <dmedia/dm_audio.h>
     #include <dmedia/audiofile.h>

     DMstatus afGetFormatParams(AFfilehandle file, int track,
				DMparams *params)

PARAMETER    [Toc]    [Back]

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

     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 used here for
	      now.

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

DESCRIPTION    [Toc]    [Back]

     afGetFormatParams() retrieves all parameters associated with the audio
     data in an	AFfilehandle structure for an audio track.  It obsoletes the
     individual	routines afGetSampleFormat(3dm), afGetChannels(3dm),
     afGetRate(3dm), afGetCompression(3dm), and	afGetCompressionParams(3dm).

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

     DM_AUDIO_FORMAT	   Sample format.  Will	be DM_AUDIO_TWOS_COMPLEMENT,
			   DM_AUDIO_UNSIGNED, DM_AUDIO_FLOAT, or
			   DM_AUDIO_DOUBLE.

     DM_AUDIO_WIDTH	   Sample width	in bits.  For integer sample formats,
			   it will be an integer value between 1 and 32.  For
			   format DM_AUDIO_FLOAT it will be 32,	and for
			   DM_AUDIO_DOUBLE it will be 64.

     DM_AUDIO_CHANNELS	   Channel count.

     DM_AUDIO_RATE	   Sampling rate.

     DM_AUDIO_COMPRESSION  Compression type.  Will be DM_AUDIO_UNCOMPRESSED or
			   one of the supported	compression parameter values.
			   In addition,	any parameters associated with the
			   compression,	such as	DM_AUDIO_BITRATE, will also be
			   retrievable here (see afGetCompression(3dm) and
			   afGetCompressionParams(3dm)).



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afGetFormatParams(3dm)					afGetFormatParams(3dm)



     DM_AUDIO_PCM_MAP_SLOPE    [Toc]    [Back]

     DM_AUDIO_PCM_MAP_INTERCEPT    [Toc]    [Back]

     DM_AUDIO_PCM_MAP_MAXCLIP    [Toc]    [Back]

     DM_AUDIO_PCM_MAP_MINCLIP    [Toc]    [Back]
			   Slope, intercept, minimum and maximum clipping
			   values for PCM mapping (see
			   afGetVirtualPCMMapping(3dm) for a detailed
			   explanation).

     When a file is opened for reading via a call to afOpenFile(3dm), the
     track will	contain	a full description of the audio	data format, including
     data type,	sample width, number of	channels, sample rate, compression and
     any associated parameters,	and PCM	mapping	information.

CAVEATS    [Toc]    [Back]

     Note that this library will continue to support new file formats and thus
     other data	formats	than the ones described	above.	Since the Audio	File
     Library is	a Dynamic Shared Object	(DSO), it is possible for this call to
     return parameter values not found in <dmedia/dm_audio.h> at the time of
     programming.  Programs should be written to at least reject files with
     formats they are not written to handle.

SEE ALSO    [Toc]    [Back]

     afOpenFile(3dm), afReadFrames(3dm), afWriteFrames(3dm),
     afInitFormatParams(3dm), afSetVirtualFormatParams(3dm),
     afGetConversionParams(3dm)


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