dmMPEG1AudioHeaderGetBlockBytes(3dm)

NAME
     dmMPEG1AudioHeaderGetBlockBytes - gets expected length in bytes of any
     compressed data block.


SYNOPSIS
     #include <dmedia/dmedia.h>
     #include <dmedia/dm_audioutil.h>

     DMstatus dmMPEG1AudioHeaderGetBlockBytes(DMMPEG1audiodecoder decoder,
                                         unsigned char *cmpData,
                                         int *blockSize)


PARAMETER
     decoder   DMMPEG1audiodecoder structure, created by
               dmMPEG1AudioDecoderCreate(3dm), specifies and stores the signal
               processing parameters.  It describes the kind of decompression
               to perform, and holds the between-block state of the
               decompressor.  It is initially generated by calls to
               dmMPEG1AudioDecoderCreate(3dm) and
               dmMPEG1AudioDecoderSetParams(3dm).
               dmMPEG1AudioHeaderGetBlockBytes modifies DMMPEG1audiodecoder
               structure to reflect the header on the compressed data block if
               one is found; decoder parameters may then subsequenly be
               queried using dmMPEG1AudioDecoderSetParams(3dm) to determine
               the decoding parameters of the encoded bytes.


     cmpData   points to a block of data bytes presumed to constitute the
               compressed data stream.


     blockSize pointer to an integer return value; indicates the expected
               length in bytes of any compressed data block starting from the
               header that was found. If no valid header was found zero is
               returned.  This may be useful number of bytes to queue up for
               calls to dmMPEG1AudioDecode(3dm).  The largest compressed data
               block possible under MPEG1 audio layer 1 is 672 bytes (32kHz
               sampling rate, 448 kbps data rate, 38 sample frames per block)
               and under layer 2 it is 1728 bytes (32kHz sampling rate, 384
               kbps data rate, 1152 sample frames per block) -- ???.


RETURNED VALUE
     Returns DM_FAILURE or DM_SUCCESS.


DESCRIPTION
     dmMPEG1AudioHeaderGetBlockBytes(3dm) extracts information from a
     compressed data stream without going so far as to decompress the data.
NOTE
SEE ALSO
     dmMPEG1AudioDecoderCreate(3dm), dmMPEG1AudioDecoderSetParams(3dm),
     dmMPEG1AudioDecoderGetParams(3dm), dmMPEG1AudioDecode(3dm).