I was just reading the story of "Uncompressed video capture on O2" on
"comp.sys.sgi.hardware" newsgroup, which is related to my stuff, and
those opionions given before all well acceptable on my behalf as well.
But as I'd be mostly using own-made (simple) synthetic video, my problem
has a bit different tone, which is in my special case very severe.
Ive been trying to get further insight on my problem explained below,
unluckily with little success, so now I turn to the world wide help :-)
I work at the Helsinki University of Technology at the Laboratory of
Computational engineering. We have a number of SGIs, e.g. 02, Octane,
Onyx among others.
Im making my PhD Thesis on audiovisual perception, therefore I need to
construct a system controlling a number of devices tru serial i/o
(rs-232) (ie lights, turntables, relays etc), and most of all, I need to
play simultaneously videofiles (with or without sound) & soundfiles (1
to multichannel) with good (< 1ms asyncrony) syncrony. This 1 ms is
because of many reasons, two are the following: the MEG
(magnetoenchelogram) method has an accuracy of 1 ms, according to
British telecom research studies, humans can perceive audio/video
asyncrony -80ms..+40ms (audio related to video) - I want to study
these fundamental issues, so my equipment should be at least a decade
(10 times) better. You understand, a dropped frame would yield to a 40
ms asyncrony between audio and video, and frames are so easily dropped..
Im not a coder, unfortanetely, but Ive been scripting Matlab > 5
years, so Id really prefer a system which softwarecore would be Matlab,
as Im doing 3-D sound file calculation also in there.
Also, Id prefer a portable system running in a laptop, but due to the
inherent asyncrony problems in Windows & Mac based OS and hardware, the
SGI seems to be the only solution. I think that with this fact many
people can agree, if not, I'd be really greatful to hear possible
Thus, Im asking you, is that whether the +/- 200 us asyncrony is really
true, what is presented in SGIs O2 white paper? Does in apply also under
"medium-heavy loads", meaning running Matlab below can you still play
video or still images in accurate sync with the audio? Also, what Id
need would be a audio/video syncrony checker. Ive been studying hard
www-pages and asking wise friends and colleagues, we could find the
stuff relating vlGetFrontierMSC etc., so is this a problem solved by a
good C-coder ,-), right?
Im searching a most ready solution that I could control from Matlab, so
does this mean that I need to find some whos is capabable of coding a
C-routine and convert it to matlab mex-file, that would check the time
stamps when audio and video frames are getting out of the ports? I.e.
is there no ready-made stuff, even though many basic functions exist??
If you tell me that I can do this with program X which costs 30,000 USD,
ok, but let me know it anyway. In "Uncompressed video capture on O2" on
"comp.sys.sgi.hardware" newsgroup Emmanuel Florac recommended
Alias|Wavefront saying that "it can
read bunches of still images from a directory and play it out directly
without processing, real time and uncompressed.... ". Is it scribtable?
What is real time?
="Generally not dropping frames, but.. "?
I thank you all most humbly and wish you all
an unforgettably good Millenium!!
non sufficit In vivo veritas