How can I avoid dropped frames in a DV AVI Firewire capture on a modern computer?

[Luke Arndt]

I hope I am posting in the right section. If not, feel free to move it to the correct area.

My issue: I am trying to find a foolproof way to capture DV AVI video over Firewire with ZERO dropped frames.

I am using a Sony PD-150 and I am going tapeless, so I am just recording "live" into a laptop.

My laptop is a Lenovo T61 with a dual-core T7300 CPU at 2.0 GHz. Has 2 GB RAM and a 160 GB SATA HD (5400 RPM, I believe). Also has a 640 GB SATA HD (5400 RPM also) in the CD-ROM slot. Both drives are freshly defragged. Running Windows XP Pro SP3.

I have used Sonic Foundry / Sony Video Capture and also Exsate DV Capture Live. I am capturing to DV AVI, and every now and then I'll experience a small chunk of dropped frames. It might be somewhere in the neighborhood of 20 in an hour, while some hours will go without losing any frames.

That doesn't seem like a lot, but it means the audio/video cut out for a split second, which could be bad depending on when it occurs. I have tried capturing to both the primary and the secondary drive, and I have next to nothing running on the computer aside from the capture program. Antivirus is disabled, and there's nothing significant going on in the background (backup, defrag, indexing, etc).

Anyway, I am looking for a "bulletproof" way to capture video via Firewire without dropped frames. What puzzles me is that this has been a problem for a long time, dating back to when my computer hardware was nowhere near what it is now.

It does seem like the more I leave the computer alone, the better chances I have of a perfect capture. But I'm just searching for something -- some program, some setup -- that would let me capture perfectly every time.

Any thoughts? The laptop becomes my "master" video source, so having dropped frames could be really bad.

Thanks!

Luke

[Chris Soucy]

Hi, Luke.................

The answer may be simpler than you think.

Assuming you can see the captured video on your laptop screen AS it's captured, start recording and have a bit of a fiddle with both Firewire connections and then give the cable a good work out to see if it's a broken conductor.

It may well be that a socket, plug or the cable itself is iffy, and those camera plugs/ sockets aren't all that robust.

Try replacing the cable no matter what you find, you never know.


CS

[Craig Parkes]

My gut reaction is if it's consistently been that way on your setup it's almost certainly drive speed.

5400rpm drives are never recommended for video capture which needs to be sustained for long periods of time, they can do the job with firewire certainly, but as they get more full or if the operating system accesses the drive from time to time for some reason, then there is an increased likelihood of dropped frames on capture. I am unfamiliar with the software you are using so can't tell if there is way to check a log to see WHY the frames might have been dropped.

Capture stability is all about continuous, stable drive speed and seek times, with plenty of overhead over what your actual data requirements are.

Beyond that, then you are looking at cabling issues, either loose connections, or some source of interference actually corrupting the signal due to poor shield/too much induction some other electro magnetic occurence that is actually messing with the signal between the camera and the computer. interference from a cellphone sitting right next to a firewire cable with poor shielding could concievable cause the sort of issue you are describing, but unless there is something common about your workflow that means the firewire cable is likely to suffer interference from electronic/radio/magnetically induced signal then I would hazard that drive speed is the culprit.

There are other possibilities to do with software/os config certainly, but theoretical and real world performance of drives is certainly different, and gets more different the more full they are or the longer they have been continuosly capturing for.

Swap cables if you haven't done that yet, because it's the cheapest option and worst case result you end up with a spare cable. After that swapthe 5400rpm scratch drive for a 7200rpm drive and see if it solves the problem.

If neither of those solves it, the next thing I'd probably check is RAM - a bad bit of RAM could potentially be the culprit (Software cache's the incoming signal to RAM before writing to the drive, which works most of the time except when some of it goes to RAM which is going bad that drops some of the data.)

[Luke Arndt]

Hi guys,

I have tried with different cables in the past. Also, fiddling with the cable at either end while capturing doesn't change anything or cause frames to be dropped. Additionally, the computer isn't "losing" the Firewire connection when I move the wire around, so it doesn't appear to be loose.

I might see if I can get my hands on a 7200 RPM drive. I forgot to mention it, but when I would capture to my secondary drive, there would be nothing else accessing that drive at the time.

Do either of you recommend any particular program for reliable capturing? Perhaps there is even one with a good buffer that would be more forgiving in the event that the hard drive has a hiccup or something.

Thanks for the advice.

Luke

[Chris Soucy]

Try downloading the test version of the latest Ulead Video Studio software.

It's capture is about as bomb proof as anyone can make it, and if that is dropping frames you have a pretty serious problem.

It ain't Avid or any of the other "high end" software, but it does the job.


CS

[Don Bloom]

Luke, the first thing is the drive as has been noted. Nothing less than 7200 period even if nothing else is running. As for a capture program check out Scenealyzer Live. It is strictly for capturing and only for DV. I've been using it for years and it's works great.

[Roger Van Duyn]

I'm not sure what's causing the dropped frames for you, probably the drive speed. However, if the NLE you use can capture live, from a workflow perspective, it makes sense to just use your NLE to capture. Are you capturing with a laptop, and editing on a desktop, or are you doing both on the lap top?

Some editing programs will allow you to install on both your laptop and your desktop. For example, with Avid, you can install to both computers. Whichever you are not using, you deactivate online, then activate the license on the other. Or if you have the dongle, you move it back and forth from desktop to laptop as needed.

It can save quite a bit of time capturing directly into your NLE instead of into an external program first. Anytime you can save a step in your work, you usually save time.

Of course, the dropped frame problem can be a real pain. When a problem is intermittent, it can be awfully hard to troubleshoot.

[Bruce Foreman]

The "dropped frame" thing becomes a non issue when you go tapeless by using a camera/camcorder that records to flash media (CF or SDHC cards). Then you no longer "capture", but simply copy the motion picture files from that media card to the drive(s) you will store them on.

Drive speed also becomes a non issue.

What will be an issue is computer processor speed. The degree of compression involved places heavy demands on computer resources. I just had to upgrade to a 2nd generation Intel Core i7 based computer and it handles AVCHD from Canon HF series camcorders and the H.264 in MOV container from Canon DSLRs with ease.

This is the way most of the market is moving these days, anyway.

[Chris Medico]

I can suggest something that I have found is 100% bulletproof for dropped frames with DV and HDV. Use a dedicated recorder and not a computer.

I have 3 of the nNovia recorders that have been workhorses for years.

If you are recording 25Mb DV then drive speed is not an issue. The automatic head parking on a low power drive could be a problem though. Most of the lower RPM drives are considered "GREEN" and have software in them that do all kinds of crazy things to save power making them unsuitable for your type of video recording.

How long are you recording at one time? My recorders with 120gig drives in them can do 4.5 hours at one time.

[Warren Kawamoto]

In addition to the above, record to tape with the PD 150, and use that as a backup in case you need to fill in the blank spots.

[Luke Arndt]

Great info, guys. Thanks, all, for chiming in.

A couple things: The tape assembly of this PD-150 is actually acting up. Most of the times, it won't "accept" a tape and just flashes a "C:31:30" message. If I insert the tape enough times and restart the camera it will let me record, but it is something I have to go through every time I want to insert a new tape.

I actually have an old nNovia recorder. It happens to have a broken LCD screen at the moment, so it's been out of service.

Right now, I am experimenting with Scenalyzer Live 4.0. So far, I haven't gotten any dropped frames. Just recently, I got daring and started to attempt to mess it up. It has done okay through a defrag and an Avast virus scan so far. If it continues to be dropped-frame-proof, I might just buy this software. The peace of mind of never having to worry about dropped frames again (or at least without doing something pretty extreme on the computer) may just be worth it.

I'll also see if I can get my hands on a 7200 RPM laptop drive. Don't believe I have any at the moment, but perhaps I can get a hold of one.

[Luke Arndt]

An update...

For the past two days, I have been capturing pretty much nonstop to my secondary 640 GB drive using the ScenalyzerLive 4.0 demo.

I have had... ZERO dropped frames so far, and have captured 32+ hours of footage. During this time, I have done minimal amounts of web browsing, but have run a chkdsk, a defrag, a virus scan, and several iterations of CrystalDiskMark 3.0.1 on the drive while capturing. Still, zero dropped frames.

So I'm liking what I'm seeing! I would imagine if things got bad enough, I could get it to drop some frames. But this is looking promising!

Edit: Anybody have ideas on what else I could do to stress/slam the hard drives? I want to find out at what point this thing will start dropping frames.

[Mark Watson]

Besides the slow drives, your RAM is marginal at only 2GB. Might be interesting to monitor your RAM usage while capturing with your original setup vs. with ScenalyzerLive. Once you start using too much RAM, then the virtual RAM (page file) is utilized, which MIGHT be contributing to your dropped frame problem. Just a guess. I was also going to suggest trying a PC card slot adapter to give you a faster connection to a portable HDD then what is available on the USB 2.0 ports; eSATA or firewire 800 for example.

Mark

[R Geoff Baker]

The simple truth is that for years and years I used a PD150 with an 800mhz PIII and a 5400rpm drive with a whopping 2 Gigabytes of RAM ... the data rate and demands of DV are so low, that there is no way that modern equipment can't do it. Yes, you had to pay some attention to technology fifteen years ago when we first started with DV, but at this point, if you are having problems I would bet my computer the issue is with a software conflict -- something is running in the background and hogging resources.

Yes, Scenalzyer Live is the best Windows tool I ever found for capture, but even with that running, virus checkers and the like can give you trouble -- a clean boot & shut down all unnecessary tasks -- as for what might cause a drive to fail, that's a tough one as the RAM buffer in a drive can smooth over most knocks, by the time you get a bang big enough to interfere with capture you have likely done permanent damage to the drive.

JMHO,
GB

[Luke Arndt]

I just added a third GB of RAM to my machine.

Still haven't dropped a single frame in ScenalyzerLive. When I said I'm looking to "slam" the hard drive, I meant in terms of stressing it, such as running a defrag, a virus scan, et cetera. I'm trying to try a worst-case scenario on the computer, and see at what point frames will begin to drop.