Minimum requirements for direct capture on APPLE laptop?

proximity

proximity

Well-known member
Hey guys,

I would love to map out what minimum specs an Apple laptop needs to fulfill to be able to do live capture (in Final Cut Pro) from the HVX-200. We've talked about this earlier, but that thread completly derailed.

Setup example:

Powerbook G4 1,66 GigaHz, 512 MB ram, 7200 rpm external Firefire 800 powered disk. - Could this work? No?, maby 720pn? Only DV? thoghts? examples, expiriments?

Or is there maby a bottleneck in the firewire bus, forcing the user to buy a firewire-to-PCIMCA adapter to route the video into the machine to flow freely out via the firewire 800 port?

Could this work on a G4 laptop that more like 1 gigahz?

We all could use a map showing what feild options we have with the HVX :)

- proximity
 
Sure, that's useful info. Still, I cant just do live capture to a 5400 rpm disk when recording DVCPROHD, and I just doubt (for tech reasons) that I could send a videofeed into the mac via firefire and out again to the disk without making a bottleneck.

Anyone tested this a lot?
 
I think you'll find that 720p24p (with pull-down removal upon capture, so it's roughly 7 or 8mb/second going to disk) or DVCpro50 Capture will work ok. DVCpro50 works fine to the internal hard drive, in my experience with a 17" powerbook, and that should be about the same data rate as 720p24p. I've done a two hour continous DVCpro50 take to the internal drive without a glitch.

If you want to record to an external drive, feed the video into the native Powerbook firewire slot, and use a cardbus firewire card for the external drive. They're about $70, and firewire 400 is fast enough for 720p24p, although firewire 800 cards are made by LaCie and others.

G-tech's G-Drives are fan-less and pretty quiet, with 7200 Hitachi mechanisims (as well as well cooled by a good heat sink design) and a pair can be mirrored for redundancy.

That's what I'm using at the moment, and I'm happy with it, although you have to be careful not to pull a cable (or power up one drive alone) once you've got the mirroring scheme implementted or you're in for a LONG rebuild process even if no damage was done before you could do more mirrored capturing with that array and file set. There are other mirror utilities that can go around that, but that's the way it is if you use Apple's free mirroring utility.

Stephen Gagne
 
Is it not possible to achieve this by connecting the external HD to the G4's FW800 port directly, instead of the PCMCIA slot?
 
Recent powerbooks (before the intel models, which are firewire 400 only) have both fw 800 and 400 ports, but they're on the same firewire bus. So there's concern that this single bus doesn't have the bandwitdth to mess with the reliability of capture to an external drive at the same time that it's taking in the camera's signal for capture.

I also think I've read somewhre that the camera's 100mbs or slower transfer speed will limit the speed of whatever firewire bus it is on, at least while it's actively sending data. Haven't tested that myself. However I'm pretty sure that it DOES limit the firewire bus to 400 speeds if a FW 400 device is on it.

If you want to save the cost of the $70 card, feel free of course to see what works for you. A few years ago, I successfully captured while writing to an external FW drive on the same firewire 400 bus on a G4 (dual 800) tower, even though it isn't supposed to be a good idea. But I'd recommend you try a LONG test -- and if you have clients that are counting on no botched takes due to dropped frames, the $70 is probably a wise investment.
 
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