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Old November 21st, 2007, 12:23 AM   #1
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dv capture issues

does anybody know of software that will log the timecode locations of dropped frames and once the capture is over, automatically return and recapture those frames and add them to the file? it doesn't seem like that would be too difficult to make.

perhaps you are wondering why i am dropping frames when I capture, which is also another problem i am trying to figure out. I have a suspicion that my firewire card is to blame but are they really all that different? they are so cheap now, it is hard to think that one is going to be so much better than another....

I'm using Vegas 8 (although I have used other software to capture and I seem to have the same problem with all of them which is why i think it is my card), a Sony DSR-11, and I am using an hp firewire card that i got at CompUSA i think for @ $30. all my software is current, I have plenty of RAM, etc. I just can't seem to capture without dropping frames. I'm willing to pay for a good card if that's what it takes but I don't want to just keep buying them until I find one that works--I mean, I want to find one that works but I guess I could use a little guidance on what to look for.

Last edited by Phillip Marlowe; November 21st, 2007 at 12:50 AM. Reason: additional information
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Old November 21st, 2007, 07:40 AM   #2
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You shouldn't be dropping frames with DV. It's likely not your card but your computer. Capture should go to a separate hard drive that doesn't have the OS or page file on it. Turn off virus checking etc while your capturing( disconnect from the internet while your doing this) IF you just have one hard drive and it is fragmented that is likely your problem.

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Old November 21st, 2007, 10:25 AM   #3
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thanks for your message Ron. I am capturing to a separate hd on a different IDE channel, and it is not connected to the internet. I have disabled my antivirus but i still have problems. by the way, i love ottawa, having lived there for a couple of years.
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Old November 22nd, 2007, 03:43 PM   #4
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Capturing challenges

I have been experimenting a little myself with DV capture (writing special capture software) in the Windows enviroment.

As long as you don't preview the DV video, there is actually very low load on both CPU and disk while capturing.
There really shouldn't be any reason for loosing frames. Still, frames do get lost and there is a reason.

To loose as few frames as possible, my experiences are:
-Capture to a disk separate from Windows
-Elevate the priority of you capture program as high as possible (either programmatically, or by means of the task manager)
-Shut down all un-needed programs and services
-Sacrifice a goat ( or in severe cases, a virgin)

Some capture programs seem to have a way to know how many frames that have been missed.
I don't know how this is done.
As I understand it, it is only by reading the captured file and analyzing the time code that you really know.

The main reason for lost frames (in my belief) is that Windows will do something (often with a higher priority) that interferes with the capture.

/Johan
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Old November 22nd, 2007, 06:02 PM   #5
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Quote:
Originally Posted by Johan Staeck View Post
Some capture programs seem to have a way to know how many frames that have been missed.
I don't know how this is done.
As I understand it, it is only by reading the captured file and analyzing the time code that you really know.
DirectShow exposes an interface from the capture driver called IAMDroppedFrames for this purpose:

Quote:
The IAMDroppedFrames interface retrieves performance information from a video capture filter, including how many frames were dropped and how many were delivered. Applications can use this interface to determine capture performance at run-time.

In addition to the methods inherited from IUnknown, the IAMDroppedFrames interface exposes the following methods.

GetAverageFrameSize - Retrieves the average size of the frames that the filter has captured.
GetDroppedInfo - Retrieves an array of frame numbers that were dropped.
GetNumDropped - Retrieves the total number of frames that the filter has dropped since it started streaming.
GetNumNotDropped - Retrieves the total number of frames that the filter has delivered since it started streaming.

Remarks

Some filters that expose this interface do not implement the GetDroppedInfo or GetAverageFrameSize method.
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Old November 22nd, 2007, 07:23 PM   #6
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Something is obviously causing an interrupt at a higher priority than the iLInk card. Is there anything else on the IDE cable? Try placing this hard drive on its own cable as Master with nothing else on the cable. OS on IDE 0 capture hard drive on IDE1 disconnect any other drives for a test.
I too like Ottawa, emigrated to Ottawa in 1970 and been here ever since.

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Old November 23rd, 2007, 02:56 PM   #7
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similiar problem

Hey, I've been capturing through my firewire cable to Final Cut Express HD and I've had times when final cut will have to locate the time code and sometimes it skipped frames which really got me mad. any solutions?
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Old November 23rd, 2007, 07:28 PM   #8
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Dedicate that PC!

Do not look for answers in your hadrware, that's probably more than fine. I have an ancient Duron 1.6 GHz and it works just fine with both internal and external/USB drives. I also have a 4 year old Sony laptop with a slow hard drive (5400 RPM) and only 512 megs of RAM and I capture both DV and HDV from that laptop to a 4200 RPM USB hard drive without dropped frames.

Your problem is more than likely in software, as mentioned above, the computer "thinks" something is more important than capturing your video. My advice is very simple - theren is absolutely no excuse not to dedicate a PC exclusively to video editing - they have gotten so cheap. I use my best PC for editing (and it's not the latest and greatest but all it has on it is Windows, SP2 and the Adobe Suite, absolutely nothing else) and have no issues. And use an older machine for internet/e-mail/messaging, etc - this one is fully armed with Zonealarm.
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