Capturing thru laptop via firewire & USB

[Renton Maclachlan]

I have a wedding coming up in a couple of weeks where the service is going to be over 2 hours long.

I use three cameras and am thinking that to save changing tapes, I would capture two cameras to laptops. I have done this one time before, capturing through Vegas, and it worked a treat. Only the laptop captured at a different speed to the tape (slow by 1 min over an hour) and seemed to vary in speed through out.

It has been suggested that some of this speed change could have been due to the laptop's harddrive doing stuff and influencing capture speed. I don't know whether this is possible or likely or not.

As an alternative, I wondered about capturing though the laptop to an external HD, and if this would overcome the problem of apparent variable speed of capture.

But then the laptop only has one firewire connection, so I would need to go from the camera to laptop via firewire, and laptop to HD via USB2.

Would this work? Any thoughts?

[Jeff Harper]

It sounds like the earlier issue was guessed at but never determined for sure. I suspect you wouldn't know until you tried.

[John Stakes]

I know a little about computers, but am still learning camcorders. Last I checked, video didn't transfer too good with USB (however I suppose the information is only traveling in one direction). Anyway you can buy a firewire pcmia card if you need extra ports. But as Jeff said, just try it out, that will give you a definitive answer. Let us know what works.

how do you capture to your laptop? just hit record on the camera, and set the software to capture??? (I guess that is something for me to try out : )

[John Miller]

Originally Posted by Renton Maclachlan

But then the laptop only has one firewire connection, so I would need to go from the camera to laptop via firewire, and laptop to HD via USB2.

Would this work? Any thoughts?

Certainly. Pretty much the standard approach - I use it all the time.

Originally Posted by John Stakes

how do you capture to your laptop? just hit record on the camera, and set the software to capture??? (I guess that is something for me to try out : )

Pressing the record button on the camcorder isn't usually communicated to the computer via FireWire. Since you won't have a tape in the camcorder (will you?), the record button won't do anything anyway. Just launch your capture software and start it capturing.

Note, many camcorders require that you don't have a tape loaded if you want to keep the camera running indefinitely otherwise it will go into standby after a certain amount of time, e.g., 10 minutes.

[John Cline]

The laptop is going to record whatever it is fed and at the frame rate at which it is fed by the camcorder via Firewire. It is virtually impossible that the laptop was at fault.

The frame rate is determined by the camcorder's internal crystal clock, not the laptop. Even though a crystal clock is very stable over time, there is no guarantee that the crystal clocks in two independent camcorders will be oscillating at EXACTLY the same frequency. Unless two cameras are running off the same clock, they WILL record at different rates.

In the professional video world, multiple cameras are physically linked together with a sync reference based on a master clock, this is called "genlocking." (There have been some situations where GPS receivers have been used to wirelessly sync cameras. After all, the GPS system is synced to the NIST-F1 Cesium Fountain Atomic Clock in Boulder, Colorado. The current version of NIST-F1 neither gains nor loses a second in about 70 million years. A newer, prototype clock, based on the oscillation of a single mercury atom, neither gains nor loses a second in about 400 million years. VASTLY more accurate than a crystal clock in a camcorder!)

Since none of us can currently afford a mercury atom clock, or to sync our camcorders to GPS signals, your best bet is to use two cameras of the same make and model but, even then, there is no guarantee that they will run at exactly the same speed. Over a two-hour recording, they will almost certainly drift apart by some amount. How much they will drift is hard to say. I have recorded multiple cameras without genlock and had less than a frame of drift over a two-hour period, on other occasions, I've had cameras drift horribly after ten minutes. It's a combination of luck and maybe the phase of the moon.

All is not lost however, you may just have to resync the cameras every so often during editing by slipping some number of frames at the edit points between the two cameras. Then again, you might just get very lucky and not have to do this at all.

John

[Renton Maclachlan]

Thanks guys for your wisdom. I thought I would pick brains before trying it out. I find things generally work out better that way.

I'm using three cameras that are essentially identical so have minimised the possibility of issues arising because differences in that department.

[Denny Gay]

Earlier posters are correct, video trandfer over USB never goes as clean as firewire.

[Dale Guthormsen]

John,

what a great post!!!

Totally explains what was happening editing my last job!!!!

It drove me crazy!!!


Is there software that would allow you to reset time codes and then it would be in time at the standard time codes??

Or does the crystal clock make each timecoded frame off??

I often use an exl2 and a gl2.

[John Miller]

I have a different take on this.

System clocks in camcorders are required to meet tight specifications. For example, an HDV camcorder requires that the system clock runs at 27,000,000 +/- 810 Hz. That means two camcorders could be "off" by 1620 Hz out of 27MHz = 0.006%. Over one hour, that's equivalent to 0.2 seconds. Similar clock requirements apply to DV camcorders. Even your run-of-the-mill quartz watch can be accurate to within 1 second per month.

Varying speed of the captured material is extremely unlikely to be due to the camcorder. If it were, you'd expect to see the same problem just playing the tape.

There are computer-related reasons as to why one of the camcorders can be out-of-sync and you can test some of them.

1. If it truly is the camcorder, capture from it with a different laptop. e.g., if you have camcorders 1, 2, 3 and laptops A, B, C and you are capturings 1 to A, 2 to B, 3 to C etc, change it to 1 to C, 2 to A, 3 to B. If the same laptop gives the sync problem then it's likely to be the laptop etc.

2. Audio. Many video-related applications derive their clock from the soundcard. This can - and does - cause slow and erratic playback. It depends on the soundcard, application and the OS. To test, temporarily disable the soundcard in Control Panel and then play the files.

3. Dropping frames. Did you notice if any frames were dropped during capture?

4. Fragmented hard drive etc. Copy one of the problem files to another computer and play it. See if it plays erratically in exactly the same places.

[Steven Davis]

My two cents;

When capturing live via usb to external, processor and ram speed as well as a clean running computer are very important. You could create a different user in your windows, that runs the minimum programs, (this excludes online gambling software).

As for the drive itself, I would have a defragged drive with a minimum amount of files already on it. You don't need the drive searching around files for space to lay the footage.

And I would do tape backup anyway, this is my wisdom in that with the tape you can archive for later, have incase you need to get something from it if your hard drive goes caput.

[Jeff Harper]

I have never had issues moving files with USB. I have had issues a time or two with firewire connections, but it was always hardware issue. I routinely move 50-100GB files around using both with no trouble.

As Stephen says though if the drive is a mess forget it anyway...clean and straighten it up first, but that is the case with all drives anyway, external or internal, as we all know.

[Renton Maclachlan]

Thanks so much for the extra info. Helpful

Out of sync is not too great an issue as the files can be stretched or shortened as easy as wink.

As some suggested, the apparent varying speed of capture I cannot be sure of. That's history now and I can't confirm or deny it - at least can't be bothered seeing if I can.

cleaning up the HD sounds like a great idea, as does having a different 'user'. I'll check that out.

Thanks for the confirmation that the firewire/USB stuff is fine.

Just have to teach my wife how to start capturing via the laptop rather than just pressing the record button...that could be difficult!! :-)

[Mel Enriquez]

Originally Posted by Renton Maclachlan

I have a wedding coming up in a couple of weeks where the service is going to be over 2 hours long.

I use three cameras and am thinking that to save changing tapes, I would capture two cameras to laptops. I have done this one time before, capturing through Vegas, and it worked a treat. Only the laptop captured at a different speed to the tape (slow by 1 min over an hour) and seemed to vary in speed through out.

It has been suggested that some of this speed change could have been due to the laptop's harddrive doing stuff and influencing capture speed. I don't know whether this is possible or likely or not.

As an alternative, I wondered about capturing though the laptop to an external HD, and if this would overcome the problem of apparent variable speed of capture.

But then the laptop only has one firewire connection, so I would need to go from the camera to laptop via firewire, and laptop to HD via USB2.

Would this work? Any thoughts?

Yes, it would work. I have been using my Dell 1505 notebook with 160gb 5400 rpm for 1.5 years now for editing and capturing. I use Ulead v10 for capturing. In editing, using Vegas 7, I didn't notice any sync or timing problems. Or maybe my clips don't really last 10-60 min straight? They are start and stop things.

I can route the capture to an external usb 2.0 HD (7200 rpm), no problems. Over a year ago, we shot a simulataneous 2-camera christmas party. Footage was 3.5 hours (4 tapes each camera). We used my sony HC3 and VX-2000. We were recording to tape and to 2 x Dell 1505 notebooks. One used the internal 5400rpm notebook HD and the other routed it to an external usb 5400rpm HD (no power supply except of the usb power). Again, I used Ulead v10 because I find it easier to transfer and see the transfer in a larger view window.

I didn't see any problems these tapes that ran continuously till the tape ran out. Or maybe my standards are low and I don't notice them. Any shift is likely not due the HD or tape. For sure, the 5 month old HC3 and the 5 year old VX-2000 were "in-sync" AFAIC.

Thought this might be of use to you.

[Renton Maclachlan]

One thing I've just thought of re capturing to laptop. I've heard it said that video should be kept on a separate drive to the one the operating system is on.

With my laptop's, they only have one drive, except for one named 'presario_rp'

Does capturing to the same HD as the operating system pose any issues?

[Jeff Harper]

It would work. That is among the worst places to store footage though as large files can slow down your OS considerably, and I emphasize "considerably". Things could get VERY sluggish and slow. You could work with it there, just not a great place to put it unless you have no choice. If you're talking relativley small files or short clips no big deal, but if you are talking 20-30-or 60 minutes worth of footage you will likely be unhappy with the performance of your OS as well as Vegas under this circumstance. If you do it defrag first.

For future reference if this is something you must do, next time you reinstall your OS you could partition your hard drive. Allocate a partition at the end of the drive that is at least 15-20% larger than the space needed to accomodate your files and you'll then have a separate drive to store video files on. This is NOT a good solution. But better than not partitioning. It would keep your video files from being intermingled with your OS and would at least prevent that part of the issue.

You might see about installing an additional internal drive if possible, though the much lower cost of purchasing a 500GB external drive (for right around $120 or more at NewEgg for example) is another option unless you travel a lot and do want to lug around extra equipment.

The very best solution, in my experience is using additional internal HD's. Having a second drive installed on your laptop, like a 250 or 500GB or whatever you would need, now that would be the BEST performance solution, period.

The other "drive" you mentioned sounds like a recovery partition that is part of the same physical disc as your C drive. It is where PC makers store the files to make it handy to reinstall your OS to it's orginal state, that is all.