External firewire enclosures at DVinfo.net

Michael Best · May 25th, 2004, 12:30 PM

Maybe I missed it in a thread but I have a firewire enclosure with a 200 gig 7200 rpm hard drive in it I was using for moving between computers. Now, with stepping into video, can I use this for direct to disk recording? Is there something about the purpose built ones that would be different. I would just try it but don't want to erase everything if it won't work. There is no display just a power supply and a firewire port. Thanks for any input.

Rob Lohman · May 26th, 2004, 04:11 AM

This will not work. A camera and your harddisk or on different
"channels/systems" on the firewire bus. So your camera does
not see it and the drive has not means (electronics / software)
to see and use your camera.

That's why those (pretty expensive) purpose built devices exist.
They have extra logic inbetween that makes the bridge between
the two and has logic for a filesystem on a harddisk and how to
write QuickTime or AVI files for example.

Michael Best · May 26th, 2004, 05:46 AM

That's what I needed to know - Thanks Rob!

Bruce Yale · May 29th, 2004, 09:50 PM

To clarify Rob's response just a bit, FireWire itself is just a communication bus. Call it a pipe. What is communicated over that pipe is how commands are passed between devices and how things "get done" - including recording video streams. In the world of FireWire there are two fundamental protocols, or standards, under which to communicate over the 1394 pipe:

1.) SBP-2 (or 3) - Serial Bus Protocol 2 (400 Mb - or 800Mb for '3'). These are commands like "copy" or "delete" that you would normally use with your "dumb" 1394 HDD to transfer files. Most of the software is "on-chip" in 1394 chipsets. This standard is usually computer-based.

2.) AV-C - Audio-Visual Commands. These are commands like "Play" & "Stop" that you would normally associate with a camcorder or a VTR. This is largely customized software (often chip-based) and very difficult for many OEM's to find an acceptable level of compliance with since there was such a HUGE latitude granted to the different manufacturers in interpreting their customization needs of the protocol during the early years of FireWire.

Since you need your camera to record when you would have your hard drive record they need to communicate a common language which in principle they do not - natively. Therein lies the rub: its darn hard to record between two devices designed under two different protocols - not to mention having to deal with so many variations of the AV-C protocol!

I know this seems to be a pretty simplistic rendition of the problem (and it may well be), but this is the Cliff Notes version of the plight of DVR manufacturers.

Stephen Warriner · August 5th, 2004, 10:05 PM

You could do it through a laptop. Camera to external drive, external drive to laptop.

Presently we are recording to a laptop with a 60 gig internal drive. We record public government meetings for public access. Thus far we are up to 3.5 hours in one shot, but that is about all that drive will take.

May 25th, 2004, 12:30 PM	#1
Michael Best Major Player Join Date: Apr 2004 Location: Oceanside Harbor, CA Posts: 446	External firewire enclosures Maybe I missed it in a thread but I have a firewire enclosure with a 200 gig 7200 rpm hard drive in it I was using for moving between computers. Now, with stepping into video, can I use this for direct to disk recording? Is there something about the purpose built ones that would be different. I would just try it but don't want to erase everything if it won't work. There is no display just a power supply and a firewire port. Thanks for any input.

May 26th, 2004, 04:11 AM	#2
Rob Lohman RED Code Chef Join Date: Oct 2001 Location: Holland Posts: 12,514	This will not work. A camera and your harddisk or on different "channels/systems" on the firewire bus. So your camera does not see it and the drive has not means (electronics / software) to see and use your camera. That's why those (pretty expensive) purpose built devices exist. They have extra logic inbetween that makes the bridge between the two and has logic for a filesystem on a harddisk and how to write QuickTime or AVI files for example. __________________ Rob Lohman, visuar@iname.com DV Info Wrangler & RED Code Chef Join the DV Challenge \| Lady X Search DVinfo.net for quick answers \| Buy from the best: DVinfo.net sponsors

May 29th, 2004, 09:50 PM	#4
Bruce Yale nNovia, Inc. Join Date: May 2004 Location: San Jose, CA Posts: 21	To clarify Rob's response just a bit, FireWire itself is just a communication bus. Call it a pipe. What is communicated over that pipe is how commands are passed between devices and how things "get done" - including recording video streams. In the world of FireWire there are two fundamental protocols, or standards, under which to communicate over the 1394 pipe: 1.) SBP-2 (or 3) - Serial Bus Protocol 2 (400 Mb - or 800Mb for '3'). These are commands like "copy" or "delete" that you would normally use with your "dumb" 1394 HDD to transfer files. Most of the software is "on-chip" in 1394 chipsets. This standard is usually computer-based. 2.) AV-C - Audio-Visual Commands. These are commands like "Play" & "Stop" that you would normally associate with a camcorder or a VTR. This is largely customized software (often chip-based) and very difficult for many OEM's to find an acceptable level of compliance with since there was such a HUGE latitude granted to the different manufacturers in interpreting their customization needs of the protocol during the early years of FireWire. Since you need your camera to record when you would have your hard drive record they need to communicate a common language which in principle they do not - natively. Therein lies the rub: its darn hard to record between two devices designed under two different protocols - not to mention having to deal with so many variations of the AV-C protocol! I know this seems to be a pretty simplistic rendition of the problem (and it may well be), but this is the Cliff Notes version of the plight of DVR manufacturers. __________________ Bruce Yale nNovia, Inc VP of Business Development

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May 26th, 2004, 05:46 AM	#3
Michael Best Major Player Join Date: Apr 2004 Location: Oceanside Harbor, CA Posts: 446	That's what I needed to know - Thanks Rob!

August 5th, 2004, 10:05 PM	#5
Stephen Warriner New Boot Join Date: Feb 2004 Location: Edgartown, MA Posts: 10	You could do it through a laptop. Camera to external drive, external drive to laptop. Presently we are recording to a laptop with a 60 gig internal drive. We record public government meetings for public access. Thus far we are up to 3.5 hours in one shot, but that is about all that drive will take.