produce bitrate much lower than required.

[george_zhu]

I captured some video from a Hi8 camcorder at 320*240. The origional file is in huffyuv 2.1.1. Some clips are in tungston light and shows dark and light alternatively. So I used a filter in virtualDub to remove this temporal noise and got a fairly well result. The result is also a huge avi file in huffyuv. Then I encode both the origional one and new one with xvid and divx in multipass and VBR mode 1200kps. DivX yield basically yield two files with similar size. While for Xvid, the original (noise) one is at the 1200kps, while the new (noise-removed) one is at about 700kps. I have all the set at default, QPel, GMC, I,P,B has minimum 2, maximum 31. B fram is 2 fram more than P, etc.

I looked at it more carefully, find for the noise-removed one, at 1st-pass, the status window already showed that the bitrate at something like 800kps. Is that the maximum? And does that mean 800kps is enough to get the maximum quality I indicated? Can I improve it to 1200kps and gain some extra?

BTW: Can anyone suggest some articles on web or some books explain these stuff in more detail? Thx

[Teegedeck]

Your second pass can't get bigger than your first pass.

You could try to remove noise less radically, try a high-bitrate custom matrix, or use quant=1.

[crusty]

BTW: Can anyone suggest some articles on web or some books explain these stuff in more detail? Thx

Read all the stickies on top of page first please.
Also read all the topics mentioned there.

[Koepi]

Since RC1, second pass _CAN_ exceed first pass size by using quant 1 frames. Though still there exists a saturation point.

Koepi

[george_zhu]

Originally posted by crusty
Read all the stickies on top of page first please.
Also read all the topics mentioned there.

I mean something explain more about the encoding mechanism, like quantization in a more semi-professional way. Thx.