VirtualDub isn't compressing properly

[legionpc]

I tried to convert a 430MB MPG file to divx (the original file the mpg came from was a 130mb divx which i accidentally deleted, hence the re-encode attempt) and the outputted divx file was larger than the original mpg! I'm sure I have all the settings right, and I even tried following one of the guides to compress to divx on this site, nothing worked.

Why isn't my file being compressed back to around its original 130mb size? (Settings were for video full processing mode and compression is divx 5.0.2 and audio was full processing mode)

[mats.hogberg]

What encoder did you use for audio?
Also, as the source material for the original DivX and the one you created isn't the same, the output size wont match, even if the difference shouldn't be that much.

/Mats

[legionpc]

Didn't use an audio encoder, however for audio compression codec in virtualdub i selected mp3.

[mats.hogberg]

Well then, you used an MP3 encoder. Did you use the same bitrates for both audio and video as the original DivX? Did the original DivX include MP3 encoded audio, or did it use some other encoding method?
My point is: OK, even if the source material isn't exactly the same, the size of the DivX encoded AVI should be at least in the same ball park, provided that the same encoding methods are used, and the same bitrates are used. If not, they may be not related at all!

/Mats