vceGetWaveInfo

Returns wave header information for a given encoding value.

Prototype

DWORD vceGetWaveInfo ( CTAHD ctahd, unsigned encoding, VCE_WAVE_INFO *waveinfo, unsigned size)

Argument	Description
ctahd	Handle returned by ctaCreateContext or ctaAttachContext.
encoding	Encoding ID (for example, VCE_ENCODE_NMS_24).
waveinfo	Pointer to the buffer to receive the following VCE_WAVE_INFO structure: typedef struct { DWORD size; WORD format; WORD nchannels; DWORD samplespersec; DWORD datarate; WORD blocksize; DWORD bitspersample; } VCE_ WAVE_INFO; Refer to the Details section for a description of these fields.
size	Size in bytes of the waveinfo buffer.

Return values

Return value	Description
SUCCESS
CTAERR_BAD_SIZE	size is less than the size of DWORD.
CTAERR_NOT_FOUND	No wave information found for specified encoding.
CTAERR_INVALID_CTAHD	Context handle is invalid.
CTAERR_SVR_COMM	Server communication error.

Details

vceGetWaveInfo returns information from the Voice Message service WAVE information table for a specified encoding. The Voice Message service maintains a table that maps encoding values to WAVE file header information. vceCreateFile uses this information to create a new WAVE file, and vceOpenFile uses it to determine the encoding of the file. For more information about WAVE files, refer to the Microsoft Windows Multimedia Programmer's Reference.

The table initially contains compiled-in entries for known encodings. Use vceSetWaveInfo to add new entries.

The VCE_WAVE_INFO structure contains the following fields:

Field	Description
size	Size of the structure, in bytes. This is set to: sizeof (VCE_WAVE_INFO)
format	The WAVE format type as defined by Microsoft. For example, WAVE_FORMAT_PCM (defined in the Microsoft header file mmreg.h).
nchannels	Number of discrete channels in the format. Use 1 for mono and 2 for stereo.
samplespersec	Sample rate in samples per second.
datarate	Average bytes per second.
blocksize	Minimum block size of the data. For PCM data, the block size is the number of bytes in a single sample.
bitspersample	Number of bits per sample.

Example

/* Display contents of WAVE info table */
/* Sample output:
    *
    * Encoding  Wave Type  M/S  SampleRate  DataRate  Block Bits
    * ----------------------------------------------------------
    *       1         56   M       8000         2100     42   2
    */

void myShowWaveInfo (CTAHD ctahd)
{
  unsigned      encoding;
  VCE_WAVE_INFO waveinfo;

  printf("Encoding  Wave Type  M/S" "  SampleRate  DataRate  Block Bits\n");
  printf("------------------------" "----------------------------------\n");
  for (encoding = 0; encoding < 256; encoding ++)
  {
    if (vceGetWaveInfo(ctahd,encoding,&waveinfo,sizeof waveinfo)!= SUCCESS)
            continue;
        printf("    %3d        %3d   %c" "     %6d       %6d     %3d  %2d\n",
               encoding,
               waveinfo.format,
               waveinfo.nchannels == 1 ? 'M' : 'S',
               waveinfo.samplespersec,
               waveinfo.datarate,
               waveinfo.blocksize,
               waveinfo.bitspersample); }
}

Sample run

Encoding  Wave Type  M/S  SampleRate  DataRate  Block Bits
----------------------------------------------------------
    1         56     M      8000        2100    42   2
    2         56      M      8000        3100    62   3
    3         56      M      8000        4100    82   4
    4         56      M      8000        8200   162    8
   10          7      M      8000        8000     1    8
   11          6     M      8000        8000     1   8
13          1     M      8000       16000     2 16
   14         23      M      6000        3000     1   4
   15         23      M      8000        4000     1   4
   16          1     M     11025       11025     1   8
   17          1      M     11025       22050     2 16
   22         17      M      6000        6600   244   4
   23         17      M      8000        8800   244   4