dx_rec and dx_play on the same channel

From: Thomas Fejes

Dave,

The terminology can be very confusing because so many different terms are used to refer to the same thing.

>Vox resouce =? Voice Device =? Voice Channel
Yes, these generally refer to the same thing: a DSP device (aka VOX or DX device) that can be used for playing/recording and detecting/generating tones.

Try routing only half-duplex (SC_HALFDUP) between the recording VOX device and the network device (so that the VOX device listens to the network device).

In the case of your T1 board, the network device is known as a DTI (digital trunk interface) device, so use SC_DTI.

For your analog board, the network device is referred to as a LSI (loop start interface) device or AG (analog) device. So, for it, use SC_LSI with nr_scroute. Note: with the analog board, use the handle that you got from dx_open with both SC_LSI and SC_VOX - a dxxxBxDy device on an _analog_ board is actually composed of two devices: a network device (AG device) and a VOX device.

Timeslot routing causes much confusion, so try to read up on it in the SCbus Routing Guide and SCbus Routing Software Reference for Windows.

nr_scroute is merely a convenience function wrapping the underlying dx_listen/dt_listen/ag_listen and dx_getxmitslot/dt_getxmitslot/ag_getxmitslot functions. It might be helpful to look at the source code of nr_scroute, which is in the ...\Dialogic\sctools directory.

As an alternative to using two channels to achieve your application, you might be able to consider using the CSP (Continuous Speech Processing) API (in particular, the ec_stream function) to achieve simultaneous play and record from one VOX device. Please read the Intel Dialogic Application Note titled "Low-Density Audio Streaming with Voice Resources on Intel Telecom Products". It is available from:
http://www.intel.com/network/csp/applnots/9085an.htm

There are some limiitations regarding using CSP that might not be evident from the AppNote and CSP API documentation:
1) CSP full-duplex play/record can only be done on CSP-capable boards running CSP-capable firmware (d41jcsp.fwl for D/41JCT-LS, spanplus.fwl for D/240JCT-T1, or spe1csp.fwl for E1 JCT boards such as the D/600JCT-1E1). These firmware files are specified for each board in DCM under the Misc tab.
2) With the D/240JCT-T1, CSP and ISDN are mutually exclusive. So, if you are using ISDN on this board (as opposed to a CAS / T1-robbed bit protocol), you will not be able to use CSP. Intel sell another board called the D/480JCT-1T1 for marginally more than the D/240JCT-T1 (but significantly less than the D/480JCT-2T1) that allows you to use both ISDN and CSP together on the one board. (A similar discussion applies to those using E1 boards such as the D/300JCT-E1).
3) There are limitations on the audio format when playing and recording simultaneously using CSP on JCT boards. See Section 1.3.1 titled "Supported Data Formats on SpringWare Boards" in the Continuous Speech Processing API for Linux and Windows Programming Guide (http://resource.intel.com/telecom/support/releases/winnt/SR511FP1/onldoc/htmlfiles/cspswrp/csp-pr10.htm). If you are using SR 6.0, then look in the corresponding document.

Hope this helps.

-Tom

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Received on Thu Jun 23 17:18:40 2005