Interlacing lines in capture

[bugeyes]

I use VirtualDub and mjpeg to capture from cable TV.
I have a BT878 capture card installed.
I can capture with 0.20% frame losses and with
30% of the CPU load.

I observed that I cannot capture in overlay mode.

The problem is that the image quality in the
preview mode is far worse then in overlay.

The image is jerky and some interlace lines
appear. And this bad quality is kept when I
capture. When reencoding (compressing) VirtualDub
deinterlace filters do not work.

1)Is there any way to capture the image with the
overlay quality?
2)What's the difference among them, and why this
happens?

[Steff]

The captured file will always be the same - regardless which display mode during the capture-process you choose.
Overlay mode while capturing only works with some lower resolutions.

In fact, the preview mode ist WYSIWYG (what you see is what you get).
If you encounter problems with interlaced material (as I do) there is a way to fix it with Avisynth afterwards. But you have to re-encode the whole stuff.

Greets
Steff

[jggimi]

Have you read our Capture FAQ (http://forum.doom9.org/showthread.php?s=&threadid=32575) and Capture Guide (http://www.doom9.org/capture.htm)?