Search found 13 matches

by Amélie
Mon Nov 07, 2011 5:03 pm
Forum: Discussion about OpenViBE
Topic: Arduino serial port
Replies: 5
Views: 7228

Re: Arduino serial port

Hello, I worked with an arduino board for its digital outputs, maybe I can help you. I am not sure to understand what you want to do : do you want to acquire data from the arduino board in an openvibe-driver ? If yes, did you already program the arduino board so that it acquires data and send them t...
by Amélie
Fri Sep 02, 2011 9:51 am
Forum: Discussion about OpenViBE
Topic: realtime and delay
Replies: 16
Views: 15331

Re: realtime and delay

Hello Jozef,

I think it will not be a problem for the measure, as I already deactivate the drift correction (to treat all data as fast as possible when they are received) and I use just one machine.

Regards,
Amélie
by Amélie
Thu Sep 01, 2011 1:48 pm
Forum: Discussion about OpenViBE
Topic: realtime and delay
Replies: 16
Views: 15331

Re: realtime and delay

It is an important aspect of my delay problem, but as I am using simple scenario with few boxes, the delay seems to be introduced mainly by the "acquisition" part (the order of magnitude is 2 to 12 ms for scenario/effector activation, 30 to 60 ms for acquisition server->client). I would like to test...
by Amélie
Mon Aug 29, 2011 9:46 am
Forum: Discussion about OpenViBE
Topic: realtime and delay
Replies: 16
Views: 15331

Re: realtime and delay

Hello, thank you both for this instructive discussion ! I will try to reduce the delay at different levels, and see if it is enough for my use, even with acquisition server's buffering. Drift correction is Ok, I noticed immediately that it makes delay vary much more :) I can certainly spare time in ...
by Amélie
Mon Aug 08, 2011 6:24 am
Forum: Discussion about OpenViBE
Topic: realtime and delay
Replies: 16
Views: 15331

Re: realtime and delay

Hello, I tried with lower block-size, but unfortunately one of my acquisition devices doesn't allow a real-time processing under 32 samples per block. I noticed that the delay is lower and less variable when deactivating all network connections, anti-virus etc. If you don't need to run the acquisiti...
by Amélie
Wed Aug 03, 2011 8:16 am
Forum: Discussion about OpenViBE
Topic: realtime and delay
Replies: 16
Views: 15331

realtime and delay

Hello all, I want to measure the treatment time of a BCI loop using OpenViBE and different acquisition systems and drivers, to evaluate the delay between the user's decision and the result (display or effector activation). If necessary, I want to identify which steps take a long or variable time. To...
by Amélie
Wed Jul 06, 2011 10:51 am
Forum: Driver development
Topic: type of sampling frequency
Replies: 1
Views: 2737

type of sampling frequency

Hello all, a new question about a choice in Openvibe acquisition server : why is the sampling frequency an integer ? Why not a float32 for example ? Some acquisition devices can propose non-integer sampling frequencies, so a drift is introduced (but the drift correction manages this well). Best rega...
by Amélie
Fri May 27, 2011 9:32 am
Forum: Driver development
Topic: question about signal data type
Replies: 4
Views: 4833

Re: question about signal data type

I found it was a strange choice, now I understand.

Thank You Yann !
by Amélie
Fri May 27, 2011 7:04 am
Forum: Driver development
Topic: question about signal data type
Replies: 4
Views: 4833

Re: question about signal data type

Hello Jozef

I agree with you, it's great that the designer allows double precision. But my acquisition device also provides double precision data, and this precision is lost in the driver, which requires simple precision data. This is what I do not understand.

Best regards,
Amélie
by Amélie
Thu May 26, 2011 8:08 am
Forum: Driver development
Topic: question about signal data type
Replies: 4
Views: 4833

question about signal data type

Hello, I am developping a driver and I just encountered something curious : in the Designer, the type of signal samples is float64, so I though no precision would be lost if the driver acquires double precision data. But in the driver, the buffer that has to be filled with these samples and sent to ...
by Amélie
Thu Dec 02, 2010 8:21 am
Forum: Box and application development
Topic: signal informations
Replies: 4
Views: 3879

Re: signal informations

It is the format of the files generated by the Biomea acquisition system that we use.
Indeed, the only software I know to read this format is provided by Cambridge Electronic Design (Spike2). But I don't know much more about it :roll:

Amélie
by Amélie
Wed Dec 01, 2010 11:21 am
Forum: Box and application development
Topic: signal informations
Replies: 4
Views: 3879

Re: signal informations

Hi Laurent,

it was simple and my box works now perfectly.
I did not think these informations would be available at initialization (I wondered when the signal-stream header was receive exactly).

Thank you very much !
Amélie
by Amélie
Fri Nov 26, 2010 3:29 pm
Forum: Box and application development
Topic: signal informations
Replies: 4
Views: 3879

signal informations

Hello all, I am writing a box whose task is to write a signal from the acquisition client (eventually with some known modifications) and other information channels (text marks) in an smr file. Is it possible to get informations on the signal (channels number, sampling rate ...) when initializing the...