How do you know the cause of dropped frames capturing VHS?

[bigbadben]

Hi guys,

Say I am capturing a 3 hour VHS tape in Virtualdub and I notice 88 dropped frames when I finish recording. My cpu usage while capturing with Lagarith is 5%. How can I find out or know which of these frames are due to my system or which are due to the VHS source?

[davexnet]

Hi guys,

Say I am capturing a 3 hour VHS tape in Virtualdub and I notice 88 dropped frames when I finish recording. My cpu usage while capturing with Lagarith is 5%. How can I find out or know which of these frames are due to my system or which are due to the VHS source?

If you're aware of a bad spot on the tape, you may want to capture just that area, say 30 seconds before and after,
to see how your capture method is working and handling the situation

Some capture devices are able to handle a damaged tape better than others.

Make sure you have plenty of disk space and that you defragment it as much as possible before starting

[johnmeyer]

Years ago (early 2000s) I wrote a guide on how to capture analog video and I asked, "How many dropped frames is acceptable?" I then answered my own question with "None").

So, eighty-eight dropped frames is eighty-eight too many.

You did not provide any information on the hardware you are using. Video capture problems are often due to things other than the CPU. In fact, in my own experience, I have never seen any dependence on CPU speed, even in computers I was using twenty years ago. Much more important are device drivers, DMA settings, BIOS settings, and all the settings related to whatever connection your digitizing hardware uses to interface to the computer.

Having said that, you need to watch the dropped frame counter while capturing. If your VHS tapes have big gaps, where the video goes to snow because you left a gap on the tape (i.e., you didn't queue up the tape when starting the next recorded segment) then you can certainly get dropped frames as the capture hardware tries to re-sync to the snow and then, when the next video starts, the first dozen frames or so doesn't have a consistent sync signal.

If that is what is going on, just ignore the dropped frame count.

[bigbadben]

On my last few tapes I connected an external hard drive and recorded to that and disabled my internet connection and it only dropped 1 frame. So those 88 frames dropped were probably due to hard drive activity because I was recording to my boot drive?

I am using a Diamond VC500 connected to my VCR connected to my computer. When I buy a half-TBC like an ES15 hopefully that will prevent frames from being dropped and clean up the signal a little bit. Then I’ll go through the painstaking process of recapturing everything to account for those dropped frames which are really, really annoying.