Virtualdub: Motion vs. Picture? (Downconverting)

[alicizmar]

Not even Google seems to be helping me with this one.
I've got a video that's too high a resolution for *most* people I'm going to give the video to, since most of them have "normal" (read:slow) computers that can't play them back properly.
So I'm downconverting it, and hit a hiccup I can't seem to figure out. If I use "nearest neighbor" in the resize filter in VDub, it comes out ridgy and blocky but the motion is like the original and fluid and "life-like". Since the ridgy, blocky problem was there, I tried hiking up the bitrate and applying Precise Bicubic (yes I just read you should use Bilinear for DivX stuff).
Now, the picture itself is outstanding and about perfect. On the other hand, the motion in the picture is now "ghosty" and more film-like rather than the live look the original and the nearest neighbor had.
Since I never knew a resize filter could mess with the motion of it (never messed with resizing in VDub until now), I'm just a little bit confused.:p What filter should I use instead? Or is bicubic fine, but I picked the wrong one (A=-1.00)?

Sorry if that was a bit long.

[setarip_old]

Hi!

Please load the original video that you created (before downconverting) into GSpot and post a screen capture back here...

[alicizmar]

OK, screenshot's attached.

[seunosewa]

I tried hiking up the bitrate and applying Precise Bicubic
You probably made other changes that affected the motion. Your reizing algorithm doesn't affect motion. Try using the same bitrate and other settings both times. Cheers.

[alicizmar]

Well if this is any indication, I tried running it through Lanczos instead, and I didn't encounter the blurring I did with the Bicubic filter (in the same default Resize plugin with VDub 1.7.7).
Perhaps I stumbled across some sort of bug in the Bicubic filter? All I changed when going from Nearest Neighbor to Bicubic was the bitrate increase, and I've never seen a picture get ghosty from *increasing* the bitrate.

[foxyshadis]

No, it's just that nearest neighbor is the sharpest possible algorithm without extra sharpening, as ugly as it is. Bilinear, bicubic, and even spline & lanczos are less sharp, from softer to sharper. Try saving it uncompressed or lossless or just watch the avs script - you'll notice how much blurrier bicubic or bilinear seems compared to what you're used to.

[alicizmar]

No, it's just that nearest neighbor is the sharpest possible algorithm without extra sharpening, as ugly as it is. Bilinear, bicubic, and even spline & lanczos are less sharp, from softer to sharper. Try saving it uncompressed or lossless or just watch the avs script - you'll notice how much blurrier bicubic or bilinear seems compared to what you're used to.
I get what you mean. Could be the whole problem in a nutshell.:thanks:
Though I am wondering what all those A=- stuff is about in the Bicubic, because I'm thinking it, too, may have caused the ghosting problem, exaggerating the blurring and...well, you get the picture.

[foxyshadis]

B and C just modify the nature of bicubic. (MPC calls B "A" for some reason.) At one extreme the function becomes nearest neighbor, at the other it becomes bilinear, in between are varying degrees of sharpness and ringing. A resizer can't cause ghosting or blending, though, that's something a temporal filter would do. If you mean something else, it's best to post a picture showing the effect.