Why might I be dropping frames?

[oLLie]

I drop a frame probably once every 1000-1500 frames.
It isn't very often, but I thought I would get 0 dropped frames with my fancy shmancy setup (at the time I got it).

I capture using VirtualVCR in WinXP Pro (SP1).
My system is:
Gigabyte GA-7VRXP
AMD XP2000+ (running at stock clock)
Radeon 9500 softmodded into a FireGL
40GB Maxtor 7200 RPM HD (OS/Programs drive)
Two 80GB Seagate 7200 RPM HD's stripe-raided together (this is the drive I capture to)
On-board Creative audio
512 MB DDR2700 ram
Do my capturing with Asus TV FM card (based on Philips SAA7133 chip)

I would be really surprised (and a little bit sad) if I captured to my OS/Programs hard drive and got less or 0 dropped frames. I guess I'll try that the next time I cap something.

Thanks in advance guys,
Ollie

[BaronVlad]

Welcome oLLie,

there are many points that can be the source for drops, please refer to the FAQ to check this.

i.g. you could also try VDub Sync for your captures

[oLLie]

Sorry I will look at the FAQ. I assume VDub Sync only works with VDub? My card only has WDM drivers so I can't use VDub and the WDM wrapper in VDub doesn't work for me. Thanks though,

Ollie

[haroldw]

Ollie:

I have a comparable system to yours:

Pentium 4 2.0gig overclocked to 2.4gig
512meg PC2700 RAM
120gig Western Digital 7200 RPM 8meg cache (system files and archive)
200gig Western Digital 7200 RPM 8meg cache (programs and capture)
ATI AIW Radeon 7500 for video and capture

I get dropped frames myself, at times. I took a look at the FAQ here, and noticed that the two things below were mentioned, but perhaps not emphasized enough:

1. The higher the resolution you are capturing at, the greater the chance of dropping frames (due to the higher bandwidth coming across the cable.)

2. The better the quality of the original signal, or videotape the less likely you will have frame drops. Conversely with a marginal or low quality signal coming through there is a much greater chance of having more dropped frames.

I would not worry about one dropped frame about every 1000-1500 frames. Which works out to about one dropped frame every 16-25 seconds. At 30fps you shouldn't even be able to notice that in the playback, at all. The main thing I keep an eye out for is "consecutive", or "near consecutive" dropped frames as these you may actually notice.

If you are capturing from video tape, I suggest you do a few five minute test capures and try to manually tweak the tracking to produce the least number of dropped frames. This can help, and I rarely see it mentioned.