[SOLVED] Unfixable frame drops capturing DV via 1394

[fvisagie]

Hi All,

I sincerely hope I can find a solution here to a problem that has me stumped. When capturing DV from a Sony DCR-TRV330E to my laptop via firewire, frames keep being dropped intermittently. The machine is a Dell Latitude E5420 with a 2.6GHz i5-2540M CPU, 4GB of RAM and is installed with Windows 7 32-bit SP1. I haven't been able to identify the 1394 chipset from Windows utilities or Dell documentation.

This is what I have tried to reduce or remove the problem:

• Put the DVCAM into camera mode; this produces a live feed for capturing which rules out tape errors
• Closed all unnecessary programs, including anti-virus
• Defragmented all drives
• Captured to a non-system drive
• Checked for latest Microsoft drivers (the E5420's 1394 adapter uses the generic Microsoft driver)
• Checked for latest Dell drivers
• Tried different capturing utilities
• Tried different firewire cables
• Retried with the machine at different power options (frame drops seem to occur more often when the computer fan is running)
• Disabled power management of the 1394 interface
• All remedies suggested at Windows 7 and Firewire problem, except for the UniBrain drivers
• All the other usual folk remedies for firewire-related capturing problems...

The system is completely unstressed by firewire capture. Often everything works beautifully. The processor barely registers 1%, capturing throughput is merely in the region of 3.5~4 MB/s, ScenalyzerLive is showing no storage bottle-necks etc. In fact, things are so rock solid then I've been able to do hard-drive back-ups during captures without any errors either side. Then out of the blue frames would get dropped with no way of preventing or even reducing that.

This seems to occur in batches. There'd be periods where no frames get dropped, no matter what I throw at the system. Then there'd be periods where a frame gets dropped, every few minutes apart or sometimes closer.

I have noticed a couple of interesting things in this regard. The first, as mentioned above, is that errors seem to occur more regularly when the computer fan is running. The second is that the interval between frame drops is often close to multiples of minutes, or half-minutes even. This got me wondering whether some background task is regularly checking or doing something and tripping up the capture in the process. The third happened while watching Task Manager for this. Once I was able to catch a frame drop in progress, so to speak. As the frame drop occurred, all the processes then visible in the Task Manager list had their "Memory (Private Working Set)" adjusted?! All simultaneously! Strange but true.

What conclusions can I draw from this, if anything at all? What would be the next things to look at? Any other suggestions and help welcomed!

Thanks a lot,
Francois

[turk690]

• Captured to a non-system drive

In a computer intended for NLE, a capture drive should, without exception,

• be a physically separate drive with no system files on it (as opposed to merely another partition with its own drive letter on the same physical drive as the system partition)
• preferably be a guaranteed 7200rpm drive or better (drives like WD green deliberately obfuscate this parameter because, for one, they are really only 5400rpm; not bad, but definitely not for capturing)
• be attached to its own single unique controller, such as SATA or eSATA (USB-connected external drives do not fall in this category because a USB chipset has to poll and control many devices; you can't predict what part of Windows or any of the programs TSR or otherwise will suddenly cause the USB controller to give priority to other USB devices on the same bus, causing streaming to the capture drive to stop and potentially drop frames)
• have the biggest size you can afford (probably >1TB), and onboard cache memory you can get

I've stated several times before in this forum that because of the absence of any means to connect a separate drive with its own controller, a lot of laptops simply cannot seriously be used for any non-linear editing activity. Very fortunately, many recent mid- to hi-performance laptops have an eSATA port which will meet this requirement. No, USB3 does not count because it's still ole USB (dropped frames will probably be faster this time).

[aedipuss]

i'd try a different cam. that one is getting fairly old. it may not be the computer at all. dv capture is easy on resources.

[fvisagie]

The direction my thoughts are turning in, too. Also trying this camera on another computer. Neither is trivial to arrange under the circumstances, but it's important enough...

[2Bdecided]

Try disconnecting your machine from the internet (i.e. pull out the network cable / kill the wifi). That way, no piece of software can run its auto update function.

IMO almost all the old DV capturing advice you can find on the internet is irrelevant these days. As you say, a modern PC can capture DV faultlessly while it's half asleep.

I have also seen old camcorders that drop a couple of frames at random, on perfect tapes. I have an old Panasonic machine that is consistently bad in this respect (but useful for playing some difficult tapes, so I keep it).

Cheers,
David.

[fvisagie]

• Retried with the machine at different power options (frame drops seem to occur more often when the computer fan is running)

Because of this correlation I'd suspected some kind of RFI from the computer's fan, but I had the causal relationship all wrong . Simon Handley's point about changing clock speed and audio drop-outs in this discussion Windows 7 and Firewire problem put me on the right track.

It turns out my computer needs to have C-States disabled. HyperThreading, SpeedStep, TurboBoost and Virtualization all seem OK; only enabling C-States demonstrably causes dropped frames.

I find it incomprehensible that in this day and age a communications adapter and/or driver still depend upon a timely response from the central processor for maintaining sync, given that techniques for correctly handling this in micro-processor architecture have been available at least since the '80s, but hey, at least my captures are drop-free now .