I do a lot of conversion from DVD/ .VOB to .xvid for uploading to private torrent sites. I use
Auto Gordian Knot 2.55, (AKG), and it's free, easy to use, gives great results, and runs without difficulty while multiple apps/ windows are open. I used to do Divx encoding with Dr Divx, but I had to shut down just about everything while doing an encoding, or there would be problems with the audio/ video synch. AGK will make Xvid or Divx .avi files.
VirtualDub, for the audio encoding of the .avi file, is part of AGK. Google Auto Gordian Knot, and you'll find it available free on a number of software download sites. As far as I know, you can convert .mp4 video to .avi in much the same manner as for conversion from .VOB.
If you want to rip DVD/.VOB to .avi, you will need two additional apps:
1)
DVD Decrypter: DVD Decrypter allows you to copy the DVD files, (.VOB, .BUP, .IFO, etc), from the DVD to your hard disk. The last version was 3.5.4. It worked too well. One of the major DVD distributors, SONY, I think, bought out the programmer, and withdrew it from circulation. You can get it here:
http://www.4shared.com/file/fU7trUjA/DVDD_3540_Setup.html
2) A video joiner program. I use
BoilSoft 6.54 build 142. If you want to make one .avi file from multiple .VOB files, you'll need to connect the .VOBs into one larger file, otherwise there will be differences in the audio and video bitrates, and you won't be able to join them together after the fact. I think this file contains everything to both install and register the program:
http://www.4shared.com/file/-PwzDQNC/BSJ_v654_build_142__Serial.html
So, your procedure would be, if you want ONLY an .avi version on your hard drive:
1) Put the DVD in your DVDR drive.
2) Open with DVD Decrypter, and select the .VOB files you want to convert to .avi, and decrypt.
3) Join the .VOB files with Boilsoft
4) Convert the joined .VOB to .avi
5) Recycle the original and joined .VOBs
~bito