wave(4)								       wave(4)

NAME    [Toc]    [Back]

     wave, riff	- Microsoft RIFF WAVE file format

SYNOPSIS    [Toc]    [Back]

     #include <dmedia/audiofile.h>

DESCRIPTION    [Toc]    [Back]

     The Audio File Library currently supports 13 of the commonly found	audio
     file formats, i.e., is able to recognize, read, and write sample data and
     header information	to and from files in these formats.  It	is important
     not to confuse sample or audio data formats with file formats.  The
     former refers to the bit-wise organization	of the sound samples in	the
     file, i.e., whether the format is 8-bit integer or	16-bit unsigned, etc.
     Audio file	format refers to the structure of the audio file header, the
     chunk of on-disk data which preceeds the samples and which	provides
     information about the file	to the audio program.  A single	audio file
     format may	support	a large	variety	of sample formats.

     The Microsoft RIFF	WAVE File Format (wave)	was created by Microsoft,
     Inc., as an analog	to the AIFF(4) file format.  It	consists of a
     variable-length header followed by	a contiguous block of binary data
     representing the sound samples.  Occasionally, additional chunks of nonaudio
 information will be placed after the	sound sample block.

DATA FORMAT SPECIFICATIONS    [Toc]    [Back]

     Sample Formats:
	  Two's	complement integer for 9-bit and greater sample	widths,
	  unsigned for 8-bit and smaller sample	widths.

     Sample Widths:
	  From 1 to 32 bits, inclusive

     Byte Orders:
	  Always littleendian (only applies to 9-bit and greater widths)

     Channel Counts:
	  Any positive nonzero number, 1 and 2 most common

     Compression Formats:
	  U-Law	(AF_COMPRESSION_G711_ULAW)

	  A-Law	(AF_COMPRESSION_G711_ALAW)

	  IMA ADPCM (AF_COMPRESSION_DVI_AUDIO)

     Note that WAVE ADPCM compression is not currently supported by the	Audio
     File Library.

FILE FORMAT SPECIFICATIONS    [Toc]    [Back]

     WAVE file headers can contain large amounts of additional information.





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wave(4)								       wave(4)



     Instrument	Configurations:
	  Maximum of 1 allowed.	 Any number of loops per inst.	Inst is	stored
	  in a WAVE 'playlist' containing an arbitrary number of sound
	  segments to be played	and repeated.  As in an	AIFF(4)	file, each
	  loop contains	a reference to a marker	(one in	the case of WAVE
	  rather than two as in	AIFF).	Markers	are known as 'cue's.  A	loop
	  is stored as a reference to a	starting cue, a	length in samples,
	  plus a loop count (retrievable via afGetLoopCount(3dm)).  Instparams
	  associated with this inst:


	  AF_INST_MIDI_BASENOTE
	  AF_INST_NUMCENTS_DETUNE
	  AF_INST_MIDI_LONOTE
	  AF_INST_MIDI_HINOTE
	  AF_INST_MIDI_LOVELOCITY
	  AF_INST_MIDI_HIVELOCITY
	  AF_INST_NUMDBS_GAIN

     Markers:
	  Any number of	markers	(known as 'cues' in WAVE file format) is
	  allowed. There must be at least one marker if	there are loops
	  present in the file. There may be any	number of "independent"
	  markers (not associated with loops) plus those needed	to define the
	  starting positions of	the loops present (see afSetLoopStart(3dm) and
	  related pages	for further information).

     In	addition, it is	possible to associate both a name string and a comment
     string with each marker.  The routines afInitMarkName(3dm)	and
     afInitMarkComment(3dm) will do this.

     Miscellaneous Chunks:

	       AF_MISC_COPY	       copyright string

	       AF_MISC_AUTH	       author string

	       AF_MISC_NAME	       name string

	       AF_MISC_COMMENT	       text comment string

	       AF_MISC_ICRD	       creation	date string

	       AF_MISC_ISFT	       software	name string

SEE ALSO    [Toc]    [Back]

     afInitFileFormat(3dm), afGetFileFormat(3dm), afIntro(3dm),
     afInitCompression(3dm), afGetCompression(3dm), afSetLoopStart(3dm),
     afSetLoopEnd(3dm)


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