Home of Professional Cinematography since 1996

Firewire

Published : 8th September 2003


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 technologies"

Any input on this?

Ian Ellis DP
Austin TX
600 op
f900/3 owner
http://www.texashighdef.com/



Ian,

CAT 5 Ethernet cable used for the cable can do runs of 100 meters.

According to Apple...developer of the standard.

Robert Goodman
author/producer/photographer
Philadelphia, PA



Robert Goodman wrote :

> CAT 5 Ethernet cable used for the cable can do runs of 100 meters.

Yea, but that's Ethernet, not Firewire. Different connectors, different uses.

Am I missing something?

Ian Ellis DP



>15' is about as long as a cable can competently carry a video signal.

4.5 meters (15 feet for the Old English Units crowd) is the maximum run
for 1394a firewire at S400 (400mbit speed) according to the spec.

There are cables from Focus Enhancements :

http://www.videonics.com/products/distancedv/

and Laird Telemedia :

http://www.lairdtelemedia.com/products/ultraseries.html

and TecNec :

http://www.markertek.com/

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?

Steven Gladstone
Cinematographer - Gladstone Films
Cinematography Mailing List - East Coast List Administrator
Better off Broadcast (B.O.B.)
New York, U.S.A.



Ian,

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
LA DP



Adam,

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.

Robert Goodman
Author/Producer/Photographer
Philadelphia, PA



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)

Scott Billups



> 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 in)

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?

Confusing enough?

Martin Euredjian
eCinema Systems, Inc.
www.ecinemasys.com



>Any problems/difficulties caused by delay in the repeaters? None. We >changed no software to accommodate the repeaters.

Adam,

Have you used the "extended distance" firewire cables? 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?


Ian Ellis DP
Austin TX



Laird have a solution called "DVistance"  http://www.lairdtelemedia.com

Fastware also propose a solution over fibre called "StudioLink™"

http://www.fastware.net


Gilbert Besnard
Director, Product Development
Miranda Technologies Inc.



Hi Ian,

Take a look at this site: up to 250ft with firewire (didn’t tested it myself yet...)

http://www.gefen.com/kvm/products/firewire.jsp

or visit:

http://www.orangemicro.com/repeater.html
http://www.macally.com/spec/firewire/connecting/fh110.html
http://www.cwol.com/firewire/OrangeLink_FireWire_Repeater.htm

+++ Florian Rettich Medientechnik +++



> It's an interesting question/issue. Where does "data" end and "video" >begin?

I have always made the distinction that video formats are synchronous, i.e. the receiver must expect the image at a defined rate.

Data is non synchronous, and the receiver must/ should confirm that the image has been received before the next is sent

Martin - is that an over simplification or just a paraphrase of your post?

Kevin Shaw
Director of Training
The da Vinci Academy
www.davsys.com



From: Kevin Shaw

> ... 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.

Martin Euredjian
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.

Adam Wilt