dmG728Decode(3dm)					     dmG728Decode(3dm)

NAME    [Toc]    [Back]

     dmG728Decode - implements the ITU (International Telecommunication	Union)
     Recommendation G.728 decompression	(LD-CELP).

SYNOPSIS    [Toc]    [Back]

     #include <dmedia/dm_audioutil.h>

     DMstatus dmG728Decode(DMG728decoder handle,
			  unsigned char	*ibuf, short *obuf, int	nsamples)

PARAMETER    [Toc]    [Back]

     handle    DMG728decoder structure,	created	by dmG728DecoderCreate(3dm),
	       specifies the signal processing parameters.


     ibuf      pointer to input	compressed data	buffer.	The data format	is
	       unsigned	char (8-bit).  This bitstrem buffer must consist of a
	       multiple	of 10 bytes.


     obuf      pointer to output sample	data buffer.  The data format is short
	       (16-bit).  The samples are assumed to be	two's complement.  The
	       sampling	rate must be 8 kHz.


     nsamples  number of sample	in the output buffer to	be generated. the
	       value of	nsamples passed	to the G.728 decode/decode routines
	       must always be a	multiple of 40.

RETURNED VALUE    [Toc]    [Back]

     Returns DM_FAILURE	or DM_SUCCESS.

DESCRIPTION    [Toc]    [Back]

     dmG728Decode(3dm) implements the ITU Recommendation G.728 decompression.
     The uncompressed data sampling rate is 8000 Hz.  And the compressed
     bitrate is	16000 bits/s. The mode for decoding operation can be


     DM_G728_POSTFILTERING_YES    [Toc]    [Back]
     DM_G728_POSTFILTERING_NO


     that selects a decoder with or without postfiltering.  for	speech/voice
     signal, postfiltering should be used.  For	DTMF tone or music audio, no
     postfiltering should be used.  The	mode is	set by a call to
     dmG728DecoderSetParams(3dm). Without calling dmG728DecoderSetParams(3dm),
     decoder sets default to DM_G728_POSTFILTERING_YES.




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dmG728Decode(3dm)					     dmG728Decode(3dm)



     see DESCRIPTION in	dmG728Encode(3dm) for the discussion of	decompression
     of	a part of compressed bit stream	beginning in the middle	of a
     compressed	data file.

NOTE    [Toc]    [Back]

     G.728 algorithm was developed for sampling	rate of	8 kHz.

SEE ALSO    [Toc]    [Back]

     dmG728DecoderCreate(3dm), dmG728DecoderDestroy(3dm), dmG728Encode(3dm),
     ITU Recommendations G.728.


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