dmG722Decode(3dm)

NAME
     dmG722Decode - implements the ITU (International Telecommunication Union)
     Recommendation G.722 decompression.


SYNOPSIS
     #include <dmedia/dm_audioutil.h>

     DMstatus dmG722Decode(DMG722decoder handle,
                          unsigned char *ibuf, short *obuf, int nsamples)


PARAMETER
     handle    DMG722decoder structure, created by dmG722DecoderCreate(3dm),
               specifies the signal processing parameters.


     ibuf      pointer to input compressed data buffer. The data format is
               unsigned char (8-bit).


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


     nsamples  number of sample in the input buffer to be processed. the value
               of nsamples passed to the G.722 decode/decode routines must
               always be a multiple of 2.  It will fail if nsamples exceeds
               the the maximum value specified when the DMG722decoder was
               created.


RETURNED VALUE
     Returns DM_FAILURE or DM_SUCCESS.


DESCRIPTION
     dmG722Decode(3dm) implements the ITU Recommendation G.722 decompression.
     The mode for decoding operation can be 1, 2, or 3, which correspond to
     64, 56 or 48 kbit/sec for audio coding and 0, 8 or 16 kbit/sec. for data.
     The mode is set by dmG722DecoderCreate(3dm).


     see DESCRIPTION in dmG722Encode(3dm) for the discussion of filter delay
     and decompression of a part of compressed bit stream beginning in the
     middle of a compressed data file.
NOTE
     G.722 algorithm was developed for sampling rate of 16 kHz.  If sampling
     rate is less than 16 kHz, the algorithm still works, except the upper
     bits contains less useful information.


SEE ALSO
     dmG722DecoderCreate(3dm), dmG722DecoderDestroy(3dm), dmG722Encode(3dm),
     ITU Recommendations G.722.