The DX_ECRCT data structure contains parameters for the Echo Cancellation Resource Characteristic Table.
5.9.1. DX_ECRCT Overview
In ECR mode, a voice channel can be used as a system-wide resource to perform dynamic echo cancellation on any external SCbus time slot signal. When an echo-carrying signal is provided as an input to the ECR, an echo-cancelled version of that signal is produced on an echo cancellation transmit time slot that is associated with the voice channel. The echo cancellation characteristics can be modified by activating ECR mode with the dx_listenecrex( ) function and specifying a DX_ECRCT data structure.
5.9.2. DX_ECRCT DefinitionThe typedef for the structure is as follows:
typedef struct dx_ecrct {
int ct_length; /*size of this structure*/
unsigned char ct_NLPflag /*ECR with NLP requested ECR_CT_ENABLE:ECR_CT_DISABLE */
} DX_ECRCT;
5.9.3. DX_ECRCT Parameters|
Parameter |
Description |
|
|
Specifies the size of the DX_ECRCT data structure. Use the following value to accommodate future growth in the DX_ECRCT and the possibility of DX_ECRCT structures with different sizes: |
||
|
|
||
|
Specifies non-linear processing (NLP) for the echo canceller. When ct_NLPflag is enabled (set to ECR_CT_ENABLE), it activates NLP and the output of the echo canceller is replaced with an estimate of the background noise. NLP provides full echo suppression as long as the echo reference signal contains speech signals and the echo-carrying signal does not. In this case, the echo canceller cancels the echo and maintains the full duplex connection. Note: Do not enable NLP when using the echo canceller output for voice recognition algorithms because the NLP may clip the beginning of speech. The ct_NLPflag default is disabled. |
||
|
Use the following defines to enable or disable an ECR characteristic: |
||
|
|
||
|
|
||
Click here to contact Dialogic Customer Engineering
Copyright 2002, Dialogic Corporation
Size of the DX_ECRCT
structure