VirtualDub vs. MediaPlayer - what IS happening here?????

[Lambchop]

I've captured an old VHS onto my computer, and it looks fine in Media Player, but when I try to convert it in VirtualDub, I get this funny lined effect on the images (particularly with fast movements). I am no video expert - I tried swapping interlace fields, but it had no effect. Here are two frames from the video. It shows a drumstick moving down.
Media Player - Smooth picture



VirualDub - Strange lined affect


thanks for any help

[Lambchop]

Its worth pointing out actually that I captured an NTSC video from a PAL video playing an NTSC tape. I captured as an NTSC source at 29.97fps. When I use virtualdub to convert to an NTSC VCD MPEG, any trace of this distortion seems to disappear, but it is clearly evident when using Virtualdub or when converting to a PAL Mpeg...

[kinneera]

That's just the effect of playing interlaced video on a progressive computer monitor. The reason it goes away when you convert to VCD is because the VCD is MPEG1, which doesn't support interlacing.

[Lambchop]

thanks for the input, however....
....but the effect is visible when I convert to PAL VCD - it isn't quite the same effect...the MPEG smooths it out and produces an image with avery prominent ripple where you see the lines in the image above. NTSC VCD MPEG comes out ok tho....any idea why?

<font size=-1>[ This Message was edited by: Lambchop on 2001-11-03 19:31:02 ]</font>

[Lambchop]

Another point - I dont see this effect if I capture at 352*288pixels, only when I capture full size...

[vitualis]

<TABLE BORDER=0 ALIGN=CENTER WIDTH=85%><TR><TD><font size=-1>Quote:</font><HR size=1 color=black></TD></TR><TR><TD><FONT SIZE=-1><BLOCKQUOTE>
On 2001-11-04 11:03:36, Lambchop wrote:
Another point - I dont see this effect if I capture at 352*288pixels, only when I capture full size...
</BLOCKQUOTE></FONT></TD></TR><TR><TD><HR size=1 color=black></TD></TR></TABLE>

A lot of capture cards (e.g., all the ones based on the Brooktree chip which is most TV capture cards) will throw away one of the fields when capturing at 352x240/288. If you are only capturing one field per frame, then you're not going to get interlacing problems.

Regards.

[Lambchop]

Thanks again...
What is the best way to correct for these problems at full screen resolutions, if there is a way? I presume the problem has to be rectified when capturing??? I still don't quite understand why the problem is only visible in VirtualDub and not MediaPlayer. I have a Matrox G400TV, just for the record...

[Lambchop]

Actually, I just tried a field swap filter again in VirtualDub, and it does not correct the problem, instead I get interlace artefacts elsewhere in the picture, so I'm not so sure its an interlace problem, but maybe some kind of motion artefact. I am capturing using MJPEG codec...