A couple of camera mounted converters are coming on the market (Miranda
and Everts). Both have a firewire out feature. The longest firewire cable
Ican find is 15'.
I have been told by a possibly knowledgeable person at CompUSA that 15'
is about as long as a cable can competently carry a video signal. He also
mentioned an inline device that could boost a signal for longer runs.
He quoted a website that he said sold such a device... "griffin
Search on "firewire" using equalizing networks in the connectors
for longer runs: 10 to 70+ meters depending on transmission speed (S100,
S200, or S400). (Many DV devices run at S100 or S200 and not at S400.)
At Omneon we've strung together perhaps four or five 4.5 meter cables
using Firewire repeaters from Orange Micro and run S400 for days on end
with no problems, but the repeaters make it hard to pull the cables through
smaller conduits, grin.
Adam Wilt / Video Factotum /Menlo Park CA USA
Adam Wilt wrote:
>At Omneon we've strung together
perhaps four or five 4.5 meter cables >using Firewire repeaters
from Orange Micro and run S400 for days on >end with no problems.
Any problems/difficulties caused by delay in the repeaters?
Cinematographer - Gladstone Films
Cinematography Mailing List - East Coast List Administrator
Better off Broadcast (B.O.B.)
New York, U.S.A.
Ask Joe at Evertz if there is a Rack Mount or stand alone box that does
this at the other end of the SDI cable so its a short hop to the Computer
from there in the Engineers Tent.
This will pull it off the camera and you can run a longer SDI to the device
then go Firewire from there.
B. Sean Fairburn
As you said most devices don't use the S400 spec they use the S100 spec
which has a distance spec of 100 meters depending on cabling. The cable
specs and distances are on Apple's website.
Contrary to popular belief, Firewire is a data spec and not intended to
run video. Nine feet is about all you'll get dependably.
Scott Billups - LA
Robert Goodman writes:
>Firewire output of a camera
is a data stream not video.
I think there is a difference in the way it is packeted. (This is where
the engineers chime in)
> Any problems/difficulties caused
by delay in the repeaters?
None. We changed no software to accommodate the repeaters. And we're running
isoch traffic for multiple channels of capture and playback as well as
RS-422 tunnelled in asynch packets for device control.
(The only problem caused by delay is the delay because I'm on digest
and thus about 24 hrs behind the question!)
Adam Wilt / Video Factotum / Menlo Park CA USA
>I think there is a difference
in the way it is packeted. (This is where the >engineers chime
It's an interesting question/issue. Where does "data" end and
"video" begin? I had to answer this very question for a telecom
client that hired me for some consulting work recently.
My answer was very simple :
SMPTE/EBU video standard = video.
Any other way to move digital images = data.
The distinction, in my mind, really comes down to the signal transport
standard. An HDSDI or SDSDI "video signal" is a data stream...but
it is "video".
All of it is data, it's all digital, the lines are somewhat blurred (gaussian,
of course). You could make a distinction between real-time and packetized
(non-deterministic)...but I'm not sure it would hold in all cases.
Is streaming "video" on the 'net "video", or is it
data that is displayed as constantly changing images?
> ... video formats are synchronous,
...Data is non synchronous
In a good deal of the cases this is probably the best dividing line. However,
there are image data formats that are synchronous, unidirectional (no
receiver confirmation) ... but are not "video". A very good
example is DVI, which can be though of as serial-digital RGB for computer
monitors...but not the SMPTE kind of serial-digital, rather its own format.
I consider DVI to be a data interface not a video interface.
Yet another example might be a USB (and Firewire?) interface operating
in isochronous (iso = equal; chronous = time). It is intended to deliver
packets of information at a consistent cadence for media applications
(USB speakers, USB video grabbers, etc.) without bi-directional communication
for error correction.
I think that the lines are blurred very nicely. I didn't realize this
until I had to deal with a client that knew nothing about either world:
video or digital imaging. He was constantly being confused by the use
of the terms "data" and "video" and how us in the
biz understand from context (it's that secret handshake, actually) how
the reference is being applied. Colouring data vs. colouring video in
a modern TK suite, for example, could only be explained in terms of the
difference in the transport/storage mechanism being used.
eCinema Systems, Inc.
> have you used the "extended
distance" firewire cables?
I have not. By the time the equalized cables came out we had rationalized
our system layouts to keep all the runs well under 4 meters!
>Could I take a signal out of
the Miranda for a 70' run into my dv deck? >Or do I need shorter
runs with repeaters?
Most DV decks I've used are S100 devices and a 70 foot run should be OK.
I would certainly try it first. Note that the DVCPRO decks I've used let
you set the bus speed in the menus, at least between S100 and S200. Picking
S100 (which is plenty fast for a single stream on DV data) will let you
use a longer run than S200.
The repeaters are big lumpy things a bit bigger than a miniDV tape [am
I allowed to say "miniDV tape" on the HD list, grin?] and two
cables with a repeater in the middle look like nothing so much like a
thin anaconda after having swallowed a large pig. We wound up doing rude
things with multiple cable ties to secure the non-locking Firewire connectors
on them so we could pull cables without pulling them apart. But even so
the lumpy bits impede smooth cable motion, provide handy obstructions
to trip on, etc.