dmG728Decode(3dm)

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


SYNOPSIS
     #include <dmedia/dm_audioutil.h>

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


PARAMETER
     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
     Returns DM_FAILURE or DM_SUCCESS.


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


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