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-   -   DV Transfer to PC (https://www.dvinfo.net/forum/open-dv-discussion/769-dv-transfer-pc.html)

ronluc8667 January 23rd, 2002 06:37 PM

DV Transfer to PC
 
When transfering footage via 1394 from my XL1s to my PC, my DV capture software is capturing the data real time. Is this normal or can I speed this process up? I assumed since the data is stored digitally on the XL1s, that the data could be transferred at a much faster rate to the computer rather than real time. Is this a normal thing or are there DV capture utilities that allow a faster, yet accurate, capture of the footage from the XL1s?

Thanks,
Ron

Bill Ravens January 23rd, 2002 07:05 PM

the video stream data rate of 3.6 Mb/sec from the dvcam is designed to not exceed the capacity of your hard drive. an IDE hard drive has a data thruput of 5-35 Mb/sec, depending on other processes occuring on the PCI bus of your computer. the only other playback speed you've got on the dvcam is fast forward, which will exceed the thruput of the hard drive.

ronluc8667 January 24th, 2002 07:25 AM

Does that mean I could begin the DV capture from my computer's software, then press the fast forward button on my software to initiate a fast forward on the XL1s and see if my computer can keep up with the transfer? Are there any other ways to play at 2x the normal speed or something else like that?

Bill Ravens January 24th, 2002 08:08 AM

nope!!! to both q's

Ron Pfister January 24th, 2002 08:27 AM

A bit of background: unlike other digital video formats, DV uses a fixed bit rate: 3.6 MB/s. Therefore, there is no way to get the data through the wire faster. When you fast-forward, you still get the same bit rate, but only a fraction of the data on the tape that passes by the head.

If you were to significantly increase tape speed while still reading all data on the tape, you would have to increase the rotational speed of the head-drum as well. This doesn't happen in any video tape drive I'm aware of.

As soon as we're moving to harddisk recording, the story could change considerably: Theoretically, an IEEE 1394 recording device could support 3 different output speeds: 3.6 MBytes/s for standard DV signal, as well as 200 Mbit/s (4-pin connector) and 400 Mbit/s (6-pin connector) to deliver the recorded DV files as data. Now that would be sweet!!

How about a cam with hot-swappable 40 GB drives? I'd love it! But first the drive manufacturers have to significantly reduce drive acoustic emissions. The newly introduced fluid dynamic bearings in the latest IBM 2.5" TravelStar drives are a huge improvement already. I'm keeping my hopes up! My guess is that we'll be there in 1.5 to 2 years...

FWIW,

Ron

Bill Ravens January 24th, 2002 08:35 AM

VERY interesting info, Ron. I hope there will be HD accessories for older XL1s's a lot smaller than the current Firestore/firewire HD configuration. A beltpack or even a small system to mount on the MA-100/200...wishful thinking?

Ron Pfister January 24th, 2002 08:55 AM

It could be done TODAY!
 
Good point about the belt-pack! Theoretically, this could be done today! Imagine NO mechanical parts moving in the cam other than AF and Zoom!!

All that's neccessary is the cam manufacturers agreeing on a file system and file format for these disks (how about UDF and QuickTime, respectively?).

The cam could easily supply the power to the drive if 6-pin FireWire connectors were used. However, this would suck the batteries empty quite quickly. Maybe it's time for them to bite the bullet and introduce lithium polymer batteries...

Imagine how much smaller the XL-1 (or any other cam, for that matter) would be without the tape drive!! Completely new designs would be possible... To take this one step further, the battery could be on the belt-pack as well, since the power could flow through the FireWire the other way, too. All you'd be left with then is the lens-CCD assembly, viewfinder, controls and the mic... Mindboggling!

Substitute the viewfinder with a head mounted display (HMD), and you can put the whole thing on your head (lightweight camera helmet, anyone?). Or rigidly mount it to one forearm, while the other hand holds a wireless controller...

I think technology will take huge leaps during the next 5 years, and we'll be watching it all :-)

Cheers,

Ron

Mike Bebber January 24th, 2002 02:12 PM

Ron;

The local AFKN (Armed Forces Korea Network) camera crew here in Korea is already using a camera that does not record to tape. Instead it records directly to removable 40 Gig hard drives that clip directly to the rear of the camera. I don't know who makes it but they said it was a prototype they were trying. Get this!!! The crew was telling me about the system and said that he was recording in a add one frame deleat one frame mode. That way it adds a frame to the front of the drive and deleats one from the rear. You always have the last 40 Gig worth of video you shot. Never run out of drive space!!!! Next time I see them I will try to get more information.

Ron Pfister January 24th, 2002 02:20 PM

Sneak Pic?
 
Mike,

Very interesting stuff! It would be awesome if you could get some details and maybe even a sneak pic!

Cheers,

Ron


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