Timing resolution of DirectRT

[jarvis24]

Some devices take longer to make information available to the computer than others. There is no software (including DirectRT) that can make standard input hardware faster. DirectRT can only respond to the device once the data enters the computer. It is at that point that DirectRT excels--it usually takes no more than 1ms for DirectRT to pick up any input that has become available to the computer. This is in contrast to many programs that sit and wait for Windows to "tell them" that some input has occured. This is why DirectRT can get input faster from a standard keyboard than many other programs--instead of sitting around waiting to be told what's going on (e.g., through standard keyboard events), it actually goes and checks on the status of every key on the keyboard over a hundred times per millisecond.

This brings us to the issue of the hardware getting data to the computer. Some devices can get their data to the computer within 1ms from the time the subject smacks a button (e.g., DirectIN button boxes, DirectIN keyboards). If you are using such a device then your _total_ latency/error is going to be under 1-2ms. That's from the time a button goes down to the time that DirectRT receives it. But if you are using a device that waits for 5-25ms to inform the computer that something has happened, then that latency will be included in your response times--it's unavoidable.

As far as telling what kind of delay/error you are getting, no there is no standard function for this. We have hardware and software we have developed to test this but it's not a user friendly system. If you have a particular keyboard you'd like us to test, let us know. If you send it to us we can probably hook it up and tell you what kind of latency it has.

Finally, voiceRTs are a little different. DirectRT analyzes the amplitude of the sound wave as it is coming in--this is done pretty much in real time so you shouldn't experience any significant latencies in your RTs. And for this matter, you can opt to record the responses as .wav files and then analyze the wave forms yourself (via programs like Audacity) to ensure accuracy.

See also, John's recent post re how our keyboards work:
support.empirisoft.com/showthread.php?p=186

Hope that helps,
-Blair