Biosemi software

marialaura · Post by **marialaura** » Tue Jul 15, 2008 1:22 pm

Hi,

Even I read many times on this topic ..I still have some doubts!

Actiview has two counters running continuously: one counter tracks the total of the buffered words, the other counts the total of words displayed on screen (or written to file).
The difference between the two counters is the "backlog" value, as soon as it exceeds the total ringbuffer size, an overflow error is generated and the program stops.
What should I do to mainten the difference between the two counters constant? Is it possible to control it?

thanks in advance for any suggestion.

Best regards,

Post by **Coen** » Wed Jul 16, 2008 12:50 pm

ActiView maintains a MINIMAL backlog, which is the best you can do within the constraints of the Windows operating system. Please explain why you would want to maintain a CONSTANT backlog.

Best regards, Coen (BioSemi)

marialaura · Post by **marialaura** » Thu Jul 17, 2008 10:46 am

Hi Coen,

thank you very much for you quick answer!
Well, I'm trying to explain why I need a COSTANT backlog...
I would like to implement my own acquisition signal, rather than using actiview, because for my own purpose I want to record and process the signal with only one software. This software named BCI2000 need to receive a constant blocksize (sample per channels) from the EEG system in order to extract the right features (amplitude, frequency, etc) of the signal.
I hope, this time I've been more clear....but maybe the problem is that I'm not good at programming, so I also have difficult to understand and as consequence to write.

Best regards,
Maria Laura

Post by **Coen** » Thu Jul 17, 2008 11:06 am

Reading constant sized blocks of data from the ringbuffer is no problem. A simple change to the ActView code achieves this (best to test in ActiView Light). However, this is something else than keeping the backlog constant. Actually, reading constant sized data blocks from the ringbuffer will increase the average backlog. The variable block size of ActiView is a nice feature to keep the backlog minimal (smooth scrolling when the processor is available, quick catch up when backlog is high)

Best regards, Coen (BioSemi)