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520 Voice API for Windows Operating Systems Library Reference — November 2003
DX_XPB — input/output transfer parameter block
DX_XPB
input/output transfer parameter block
typedef struct {
USHORT wFileFormat; // file format
USHORT wDataFormat; // audio data format
ULONG nSamplesPerSec; // sampling rate
ULONG wBitsPerSample; // bits per sample
} DX_XPB;
!
!!
! Description
The DX_XPB data structure contains parameters for the input/output transfer parameter block.
Use the I/O transfer parameter block (DX_XPB) data structure to specify the file format, data
format, sampling rate, and resolution for certain play and record functions, such as dx_playvox( ),
dx_recvox( ), dx_playiottdata( ), dx_reciottdata( ), and dx_recwav( ).
The dx_playwav( ) convenience function does not specify a DX_XPB structure because the WAVE
file header contains the necessary format information.
The G.726 and GSM voice coders are supported by the I/O functions that use a DX_XPB data
structure:
• The G.726 voice coder is supported by the dx_playiottdata( ), dx_reciottdata( ),
dx_playvox( ), and dx_recvox( ) functions.
• The GSM voice coders are supported by the dx_playiottdata( ), dx_reciottdata( ), and
dx_recwav( ) functions.
For a list of voice coders supported on a board, see the Release Guide for your system release.
!
!!
! Field Descriptions
The fields of the DX_XPB data structure are described as follows:
wFileFormat
Specifies the audio file format. Note that this field is ignored by the convenience functions
dx_recwav( ), dx_recvox( ), and dx_playvox( ).
• FILE_FORMAT_VOX – Dialogic VOX file format
• FILE_FORMAT_WAV – Microsoft WAVE file format
wDataFormat
Specifies the data format.
On DM3 boards, use one of the following data formats:
• DATA_FORMAT_DIALOGIC_ADPCM – 4-bit OKI ADPCM (Dialogic registered
format)
• DATA_FORMAT_MULAW or DATA_FORMAT_G711_MULAW – 8-bit mu-law
G.711 PCM
• DATA_FORMAT_ALAW or DATA_FORMAT_G711_ALAW – 8-bit A-law G.711 PCM
• DATA_FORMAT_PCM – 8-bit or 16-bit linear PCM
• DATA_FORMAT_TRUESPEECH – TrueSpeech coder
• DATA_FORMAT_G721 – G.721 coder
• DATA_FORMAT_G726 – G.726 bit-exact coder