decoding avi-divx in 3x alpha to 4x or 5x.... can it be done

[crazylegs]

i have many avi-divx files that were encoded with the old 3x alpha... is there a way to decode it and re-encode it with 4x or 5x? i want to make them playable with my xcard that is compatible with 4x and 5x with out losing picture quality! these movies will be played of a HD so no need to worry about compresion for a cd.... i just want to keep the quality of the picture...!

im a bit confused maybe you all can help me understand the difference between. avi-divx and mpg2? is a divx file a super compresed version of mpg2 or AKA mpg4? If so, why do you lose quality when you take a mpg4 files back to a mpg2? The only thing that should change is the files size right? from your typical 700mb mpg4 to 2gig or more mpg2?????

help me out guys!!!!

[bugster]

Yes, you can do this conversion with Virtualdub (and probably others!). There is a pretty good chance you will lose some quality tho. This is because mpeg4 codecs (i.e. divx) actually throw away information that it thinks you wont notice. re-encoding from this source to ANY other format is never going to be as good as the original and often slightly poorer than the 1st encode. With carefull use of the codecs tho the quality loss can be minimised. Experiment on short clips until you are satisfied with your settings.

[crazylegs]

Bugster:

can you or someone walk me through the procedures that i need to do please. IM a newbie...

thanks

[bugster]

Ok, first ensure you have both the divx 3.11 and 4.0 codecs installed (or 5.x as well if you want). Open your avi file in virtualdub by selecting file->open video file. When you have done this, go to the video menu and select full processing mode. On the Audio menu you probably want to select direct stream copy. Again on the video menu select compression. This will open a dialog box listing all the installed codecs that virtualdub can use. Select divx4 (or whatever). There will also be a configure button on this dialog, click that to fine tune any settings the codec has to offer. After all this is done select file->save as avi, enter a filename for the output file and let it run. This will take a while depending on the speed of your comp and the size of the avi. My 2.2Ghz P4 runs at about 2.5 to 3 times realtime when encoding to divx3.11, I think divx4 and 5 take a bit longer but havent tried.

Let me know how you get on.