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Department of Cognitive Science

DMDX Information

Video Modes

Only a limited number of video modes (screen resolutions and colour depths) have been tested in TimeDX (see above table), these are listed below along with the tick rates for each one. These are specified in the top parameter line of your DMDX script. For example, if your script requires 1024x768 screen resolution and 16 bit colour, you would include <vm 1024, 768, 768, 16, 0> (or alternatively <vm 1024, 768, 16, 0>) in the parameter line. At these video modes, our prototype setup did not produce any certain display errors, even when the script involved large graphics images (e.g., 4MB pictures).

DMDX Video Mode Tick Rate
800x600,8bit,0Hz 13.333ms
800x600,16bit,0Hz 13.333ms
800x600,32bit,0Hz 13.333ms
1024x768,8bit,0Hz 13.327ms
1024x768,16bit,0Hz 13.328ms
1024x768,32bit,0Hz 13.328ms
1024x768,16bit,100Hz tba
1024x768,32bit,100Hz tba

Lab users can setup display modes in TimeDX yourself if they want to see what the tick rate is for a given mode. However when the machine is reimaged then that display mode will be lost. If you need to use a display mode that has not been timed in TimeDX you will need to contact the MACCS systems administrator.

Calibrating the Digital VOX

Anyone using the microphone as a voicekey should know how to setup the microphone preamp and also how to to calibrate the digital VOX in DMDX.

RecordVocal syntax change from DMDX version 2.4

When using scripts written for DMDX 2.4 on a DMDX 3.x setup there is a problem that relates to using the RecordVocal parameter.
<t 3000> <id “RecordVocal”>

In version 3.x of DMDX it is documented that the parameter above should ensure the entire timeout period (3 seconds) is recorded. However this is not the case. Therefore, it is recommend that you use a fuller specification, e.g.,
<t 3000> <id “RecordVocal” 2500, 500>

This will ensure that DMDX will record the first 2.5 seconds and then also record an additional 500ms, i.e., still producing the 3000ms of the timeout period.