Locating dropped frames in DV captures

[neily]

Hi,

I'm capturing DV from an analogue camcorder via passthrough on my newer DV camcorder and am getting the odd dropped frame. Now when I used to do analogue captures using AVI-IO via a BT878 card, dropped frames were handled by repeating the previous frame and the idx1 List in the AVI file showed the dropped frames as having a size of zero. It was therefore easy to find the dropped frames by looking at the hex data of the AVI file.

With my DV captures I have been unable to use this method. I have used Scenalyzer and Vegas Capture. Do these programs handle drops in a similar manner or do they just drop the frame? Is it possible to find in a capture where a frame was dropped?

[neily]

Sorry to answer my own question, but I have found a little bit of info that may be of interest.

Using the Sony Vegas Capture utility, dropped frames are in fact repeated, with the audio filled in by silence. In the AVI file, in the idx1 segment, though the video frame chunk is reported as normal length, the offset from the beginning of the file is the same as the previous one.

Using Scenalyzer, the video frame is skipped, and seems undetectable in the AVI file. Somewhat disconcertingly, there doesn't appear to be any discontinuity in the audio file. It would take a bit more investigation, but I wonder whether dropped frames when using Scenalyzer lead to desyncing of the audio?