Very unpredictable size

[ThNoctus]

I'm using avisynth 2.06 with DivX 5.02pro to reencode few downloaded tv sci-fi series. Source video is good quality 640x480 tv captured, around 400 MB in size.
My problem is when i use script (nothing special: lanczos resize to 592x320, some tweak, some croping and c3d (usually around 4,4,8,8,2.8) and divx (qpel, bidirectional, 2pass, min. qnt. 2 max. 6) I got very unpredctable size.
My goal is about 350MB but i usually get around 230MB(without audio) even with 1076 or 2076 or even 4076 video bitrate... pretty confusing for me!
Any ideas?

Thanks!

[jggimi]

You need a compression test, if you're trying to get a predictable size.

You can use Gknot's compressibility test directly, if your capture is MPEG, by selecting your .mpg file(s) in DVD2AVI. If it's an .avi capture, then you can still use it, but indirectly, by using the log from a first pass where min/max quant = 2. Use the SelectRangeEvery command to select 5% of the content, then load the .log file into Gknot.

There is an avi-as-source procedure in the Gknot FAQ, though it's designed for DivX 3.

[manono]

Hi ThNoctus-

You had the 2 threads asking the same thing. So, I was trying to merge the two, and managed to screw it up, and accidently deleted DJ Bobo's reply. He suggested that you had already reached max file size (made sense to me). So then you follow jggimi's advice about how to determine the file size in advance of encoding.

Sorry DJ Bobo. My fault.

[jonny]

You can use DivX 5 Enc to make a comp. test, it's perfect in this case!

[ThNoctus]

I must admit that idea, comment that I could reach max quality was something new to me. It's interesting because when I had these type of reencoding few months ago and my main tool was only virtualdub... it responded better on bitrate settings.
After that I started with avisynth, especially I like c3d and quality is much better even in resulting smaller size final video.
I just spoted yesterday divx 5 enc and it looks promising in my problem (compressibility test) and is of course a little simplier than gknot, which I didn't use some time, but I'm short with time for gknot repetitio.

I'm 2pass freak and if everything should be o.k. with compressibility stuff... well, I'm gonna encode a lot!

I have few more ideas (maybe filters for sharpening and adding some "healthy" noise) but we will see

Thanks

[DJ Bobo]

onore manono! yurusanzo! :D