[FieldTrip] delay with realtime buffer

[SERPOLLET Amélie 228173]

Dear Fieldtrip users and developers,

Using Fieldtrip buffer for a BCI loop (in realtime), I want to measure the delay introduced by the use of the buffer.
I use two simple programs to measure it : the first one sends data to a buffer and writes CPU time in a file when a rising edge was detected in the signal sent ; the other program requests the data and also writes CPU time in a file when the same rising edge is detected in the signal received.

I checked that the delay introduced by the detection and file writing is insignificant (0.5 to 5 µs). On my computer, with 32 channels signal and chunks of 8 to 32 points, I measured very variables delays, also after deactivating the anti-virus : 1ms to more than 45ms.

Do you know what it is due to, if I can reduce it or if I can make it less variable ?

Thank you in advance.
Amélie
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.science.ru.nl/pipermail/fieldtrip/attachments/20110803/d37f8f85/attachment.html>