Recording direct to HD...COOL!

tcbetka wrote on 10/27/2008, 4:16 PM
Whoa...cool!

I was playing around with the FX1 tonight, and set-up the iLINK interface into my big PC. Not knowing what to expect as it really isn't all that well explained in the manual, I just tried to capture some video onto an empty hard drive. SLICK! Very cool. So then I reconfigured the camera into my Vista laptop and recorded some footage right into a desktop folder--again, worked great. In case someone is wondering, you don't even have to have a tape in the camera to do this, although I would--simply to eliminate the little flashing icon on the LCD screen. But as soon as you capture the device, you can see a live picture although it's slightly delayed of course. And to record it, you simply hit the record button in the vidcap. You do not have to use the record button on the camera.

So this brings up two questions for folks that might have done this before:

1) Being as how the iLINK interface on my FX1 is an S400 with a maximum baud rate of 400Mbps, I reason that I should be able to capture video with very little lag, because the USB 2.0 external drive data rate is 480Mbps. Not that it really matters much I suppose, because I am just going to let the footage pour onto the hard drive, and then process it later. But there shouldn't be a great to have Vegas buffering the video stream, the way I figure it.

2) Regarding recording with vs. without tape: The way I see it, I should be able to actually record onto tape concurrently with the vidcap stream...right? So in essence, I can capture a stream of an entire volleyball game and record all or none of the event onto miniDV tape. I am not sure if this would be important for a volleyball game, but I can see how it might come in handy for, say, recording a wedding or something, where you wanted a backup media source. Say maybe you might want to vidcap an entire 90-minute wedding, but only record 60 minutes of it onto a miniDV tape. You get my point...

But this vidcap utility is very cool. I can't see any real reason that an older laptop running XP wouldn't work just fine. It's got 1.25GB RAM, but for only capturing video, I can't see that it matters much.

Anybody else tried this at all?

TB

Comments

Chienworks wrote on 10/27/2008, 4:20 PM
Lag isn't really a factor. If the drive doesn't keep up then the video is lost. It's a real-time stream so either it works in real time, or it doesn't work at all. But, the data stream from your camera is only about 30Mbps so you've got lots and lots of headroom to work with.

And yes, it is slick. Been doing this for a couple years, pretty much ever since i got my laptop. :)
farss wrote on 10/27/2008, 4:34 PM
The reason for the lag is the amount of time it takes the camera to compress the video. What comes out the firewire port is around 6 frames later than what's in front of the camera.
That's one of the advantages of cameras with HD SDI, next to no delay.
Bob.

John_Cline wrote on 10/27/2008, 4:34 PM
I've been capturing direct to a laptop using Vegas VidCap for the last seven years, originally with DV and now HDV for the last few years. It works great, in hundreds of hours of capturing, I've never had a single problem.

DV and HDV streams are only about 3.8 megabytes per second and pretty much any laptop and hard drive can handle this. Even an external USB2 hard drive is capable of sustained transfer rates of about 30 megabytes per second and IEEE-1394 (Firewire) drives are even a little faster.
tcbetka wrote on 10/27/2008, 4:35 PM
Ah, guess I should have figured that the data stream was nowhere *near* the max capable for IEEE 1394. Thanks for confirming that.

I have a Glyph 120GB external hard drive that is shock-mounted. Not that it's super huge in terms of capacity, but it's the shock mounting that I am interested in. Actually, I bought it nearly two years ago when 120GB still meant something; and the price still reflected that. They made 250 and 320GB drives, but the price was in the several hundred dollar range way back in 2006!

My SR11 has a 60GB hard drive, and even recording an entire tournament lasting almost a full day (about 4 hours recording), we still haven't come close to filling the hard drive on that unit. So the 120GB drive should be more than enough for what I want to do. But I think the Glyph drive requires power as I recall, so it might be handy to have a (physically) smaller external hard drive with 120-250GB capacity, powered by the USB port.

What equipment are you guys using for this?

Thanks for the posts.

TB

EDIT: Forgot...do you guys record onto miniDV simultaneously, for any reason? Just curious I guess. I am also curious as to how you guys use this set-up--all on battery power, plugged in to AC power...what? I can think of a lot of cool things I can do with this set-up now, lol.
riredale wrote on 10/27/2008, 7:56 PM
Couple of things.

(1) I think Firewire for video capture operates at 100Mb/sec, even though the theoretical pipe is 400. I've read this several places. Still lots of bandwidth for DV and HDV.

(2) Practice recording to tape and disk simultaneously before doing it for real. I note that there is a 1/2 second glitch in my disk recording whenever I hit the camera's record button. This could screw up things if you are unaware it happens.
johnmeyer wrote on 10/27/2008, 9:22 PM
With DV and Scenalyzer, many people capture two, and even three, cameras into one laptop (one hard drive) all at one time. Even though the HDV data rate is identical, I'm not sure whether any of the capture apps can handle multiple HDV cameras.
Rory Cooper wrote on 10/27/2008, 11:45 PM
Very interesting

Does anyone know if capturing this way you might get a little more life from the camera battery, especially cameras capturing to a on board hard drive?
Steve Mann wrote on 10/28/2008, 12:12 AM
"I think Firewire for video capture operates at 100Mb/sec, even though the theoretical pipe is 400. I've read this several places. Still lots of bandwidth for DV and HDV."

It depends on where it is connected to the processor. If you are going through a PCI card, then 100 MBPS is the best you will ever see since that is the max speed of the PCI bus. If it's on the FSB of the processor chipset, then you can theoretically go the FSB speed, which is usually 256 MBPS.

But for video transfer, and this is something that everyone seems to forget, the Firewire 400 or 800 maximum data rate is the BURST speed. It only exists for as long as it takes for the buffer memory in the device to fill or empty. Once that is done, the best speed will be the SUSTAINED data rate which will almost always be below 100 MBPS - 25 to 50 normally.

John_Cline wrote on 10/28/2008, 12:50 AM
Steve, let's not confuse megaBITS/sec and megaBYTES/sec. The convention is to use a lower-case "b" when talking about megabits per second, Mb/s, and an upper-case "B" when talking about megabytes per second, MB/s. John Meyer used the correct convention and his statement is 100% correct.

IEEE-1394a (FireWire 400) can transfer data between devices at 100, 200, or 400 megaBITS per second. The exact transfer rates are 98.304, 196.608, and 393.216 megabits/sec or 12.288, 24.576 and 49.152 megabytes per second.

A PCI interface is capable of 1,067 Mbit/s which is 133.33 MB/s, plenty fast enough for Firewire400 or even Firewire800.

Even though USB-2 is rated at 480 Mb/sec, due to overhead and the fact that the computer's CPU is used to manage the low-level USB protocol, it rarely exceeds 240 Mb/sec in the real world. Firewire uses DMA which allows it to run without burdening the CPU with interrupts and buffer-copy operations.
Steve Mann wrote on 10/28/2008, 6:03 AM
You are correct. (Look at my timestamp). 1MB/s=8Mb/s.

But, the bottom line is that any of the protocols (except for USB-1) for external HDD should be fast enough for DV/HDV capture. Spending the extra money on Firewire-800 gains little in that purpose unless capturing from simultaneous sources on the same PC, and most certainly for RAID arrays configured for speed.




tcbetka wrote on 10/28/2008, 6:36 AM
While the FX1 has the S400 iLINK interface and transfers data at 400Mbps, I just assumed that my laptop firewire 400 interface was the same; although I could be wrong. I had to install a PCI card for firewire interface capability on my studio machine, because I didn't have any other FW ports. But I actually thought the PCI bus speed was faster than the 133MBps given here. I know that's the highest speed in a 32-bit system, but in my 64-bit system I thought it was double that. Oh well, makes no difference as it is much faster than the capabilities of the IEEE 1394 interface.

But is it valid for me to assume that the FW400 ports on my Windows laptops transfer data at 400Mbps? I guess I just thought that since they were called "firewire 400" ports, their transfer rate was 400Mbps.

Interesting discussion here though--I always seem to learn something in these threads, which is one of the things that makes this forum so helpful...

TB
John_Cline wrote on 10/28/2008, 1:27 PM
TB, all Firewire400 ports can move up to 400 megabits per second, but not all devices need to (or can) transfer data at that rate. Yes, the FX1 has a Firewire400 port, but since it's transferring video data in real-time, whether live or off-tape, the transfer rate is only about 30 megabits/sec.
tcbetka wrote on 10/28/2008, 1:58 PM
Sorry John, that's actually what I meant--not that the rate was *always* 400Mbps, but that the fastest transfer could occur at that rate. I presume that would be the burst speed anyway. I did not know that instantaneous transfer rate for these cameras though, so thanks for clearing that up. That certainly explains why folks are able to capture live streams from more than one camera simultaneously.


TB
Terry Esslinger wrote on 10/28/2008, 2:24 PM
I don't mean to highjack this very educational thread but how do you tell if you have a FW400 or 800? Are the connectors the same or do they look different?
tcbetka wrote on 10/28/2008, 2:27 PM
No sweat... I'm glad someone else finds these threads educational. I sure do.

Yes, they are different. FW800 are 6-pin connectors and look like a elongated 'D' while FW400 connectors are small rectangles, that look like they have one side dented in slightly in the middle. Once you see the difference, you'll never get them confused again.

TB

EDIT: Check out this http://en.wikipedia.org/wiki/FireWirelink[/link], and look on the right side of the page, under the sidebar. There's a drawing of each of them there.
Terry Esslinger wrote on 10/28/2008, 2:44 PM
I don't think that is right. Both of those pictured are 400. One caries power and one does not.

Edit: Further research has shownthat FW800 has 9 pin connectors but I still have not seen the shape to know what they look like
John_Cline wrote on 10/28/2008, 2:49 PM
Not exactly correct. Both the connectors you described are Firewire 400, they come in two flavors, a 4-pin version. which is used on most camcorders, and a 6-pin version which is much larger and looks like a rectangle with one rounded end. The only electrical difference between the two is that the extra two pins on the 6-pin connector provide power (up to 1.5 amps.) Both types are called "Alpha" connectors.

Firewire 800 uses a 9-pin connector and is called a "Beta" connector.
Terry Esslinger wrote on 10/28/2008, 2:52 PM
John,
What does the connector look like?
baysidebas wrote on 10/28/2008, 2:59 PM
http://8help.osu.edu/1249.htmlFirewire connectors.[/link].

Remember, Google is your best friend.
Terry Esslinger wrote on 10/28/2008, 3:04 PM
Baysidebass
Yes I just googled it before you posted and found the same site. The 800 connector in completely different in appearance than the 4 pin and 6 pin 400 connectors. Its funny, the stupid cleaks at the stores where I shop don't even ask you about whether you want 400 or 800 when you ask for a FW HD.!!!
tcbetka wrote on 10/28/2008, 4:21 PM
Yup...I screwed up. I Googled "FW800," and didn't read far enough down the page. That's where the 9-pin FW800 connector is pictured. I was trying to get out of the office, and didn't take the time to read the fine details. Sorry, my mistake.

Here's another http://en.wikipedia.org/wiki/Image:Firewire800plug.jpgpicture[/link] of a FW800 plug, taken from further down the page.

TB
farss wrote on 10/28/2008, 4:32 PM
The 1394b (aka firewire 800) connectors are vastly superior to the 1394a connectors. If you have a 1394b controller you can connect 1394a devices with the right cable.

Here's little recent anecdote. I got a job to capture 3 HDV tapes because the client thought his Dell XPS didn't have a firewire port. He pulls it out of his backpack to show me and there it was, clearly labelled "1394". He thought the connector had to bigger than that, you know, like the ones on a Mac. Poor guy, apart from paying for my time he's had to travel considerable distances by public transport to get me to do his capturing.

Bob.
tcbetka wrote on 10/28/2008, 4:47 PM
"...you know, like the ones on a mac."

That's classic right there, lol. Good one Bob!

TB
John_Cline wrote on 10/28/2008, 7:33 PM
The 4-pin Firewire connector is basically a Sony invention, it's fragile and it sucks. Why they didn't go with the 6-pin connector for everything is beyond me...