Strange Xvid bitrate problem

[thedamager]

My problem is the following:
When I set a certain bitrate in a second pass Xvid encoding, it encodes video in a significantly lower bitrate for unknown reason.

Tried everything, reinstalling codec, instaling older version (I currently use 1.1.2), changing bitrates, changing almost every other setting, switshing to single pass, loading default settings. I thought maybe something is wrong about frameserving with AviSynth (recoding HD .mov trailers for fun ), so I tried on regular avi, even trying to decompress to Uncompressed RGB and try again but final bitrate is always 1.2 to 1.5 less then set without any pattern.
I use VirtualDubMod and my PC is 100% certified stable. I bet it's something simple but I still can't see it.

It was fine until two days ago, and I didn't do anything
Any ideas? Thx in advance.

[anonymez]

Welcome to the forum

it encodes video in a significantly lower bitrate for unknown reason.

What indicates this?

[thedamager]

I just figured it's only with frameserving HD mov files 720p and up.
File was 1280x720 H.264 mov new Pirates trailer and I used following script to frameserv it: DirectShowSource("c:\1.mov", fps=23.976) . I resized and cropped it using VirtualDubMod filters to 1024x? and in second pass Xvid 2500kbps. MediaInfo showed ~1800kbps. Btw it turned out fine with backing up DVDs (vobs).

[anonymez]

If you set the bitrate to 2500kbps, that's what it was encoded at (and you can check this by comparing output file size against a bitrate caclulator). Mediainfo's value is incorrect.

[thedamager]

I also cheched by hand and the bitrate really is around 1800kbps whatever input bitrate I set (2500 - 5000). Some strange limitation, hm. It's the same with other HD .movs except bitrate error is less (around 10-20% less then input bitrate). Never mind, simple solution: I won't encode 'em. Btw other sources are fine. Long live Xvid.