From: Jim Peters (jim_at_uazu.net)
Date: 2002-03-14 12:22:58
Sar Saloth wrote:
> Changing just the "interleave" would be a tiny bit of code wouldn't
> it? I would want to avoid having multiple ways of specifying
> channels, labels, gains etc..
>
> I have looked at your "OpenEEG-1.0" specification but I couldn't
> understand how it is compatible your above example. My lack of
> comprehension was the reason I ignored it.
No -- the spec I produced would be exactly as for EDF in this regard
-- you would need all the data for the record before you could write
it out. I was designing a disk format.
For an example of a complex serial format, have a look at the ProComp
format. From the notes in Dave's code, it seems that it sends data
like this (reading left->right, then top->bottom -- I'm missing out a
lot of detail here):
Chan-A Chan-B Chan-C
Chan-A Chan-B Chan-D
Chan-A Chan-B Chan-E
Chan-A Chan-B Chan-F
Chan-A Chan-B Chan-G
Chan-A Chan-B Chan-H
Chan-A Chan-B (other data)
Chan-A Chan-B (other data)
As you can see, you get 8 samples of Chan-A/B for every one sample of
Chan-[C-H]. Neither EDF nor my format would be any good for this (or
at least they would force you into using 1/10 sec chunks for
transmission).
> As far as I am concerned, if the headers are encoded in a similar
> enough manner that conversion is easy, then conversion between your
> above "interleaved" format to EDF would be nearly trivial so I
> wouldn't consider it an issue. However, your "OpenEEG-1.0" was very
> different in some of the headers.
The idea of the format I suggested was just to keep all the fixed
binary stuff in one file, and all the variable text stuff in a second
file next to it, probably in some kind of structured text format
(i.e. easily editable).
> Yes, and an excellent reason for not tying the two formats together
> is that a tiny micro-controller could get swamped reordering the
> data at a high data rate, but once into a PC, such a thing is
> trivial. OK, I have been convinced, pure EDF is not such a great
> idea for the binary data.
You mean for the binary data on the serial connection, I guess.
Jim
-- Jim Peters (_)/=\~/_(_) jim_at_uazu.net (_) /=\ ~/_ (_) Uazú (_) /=\ ~/_ (_) http:// B'ham, UK (_) ____ /=\ ____ ~/_ ____ (_) uazu.net
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