Difference between divx and xvid, and the best codec available?

[jagabo]

Obviously I need to do some tests myself - what I was hoping for was some parameters to use so the comparisons are as equal as possible especially when comparing DivX 6.6 to XviD-1.1.2

It's difficult to give settings that are equivalent in both. Xvid gives you more explicit control over some parameters. Divx is more opague.

The single most important setting in determining speed vs quality is Divx's Codec -> Codec Performance -> Encoding Mode. Xvid's equivalent can be found in Main Settings -> Quality Preset. Divx has several presets to choose from, Xvid has only two plus User Defined. User Defined mode has seven choices of Motion Search Precision and five choices of VHQ Mode -- plus a few other options. There's no way of knowing what settings correspond exactly in the two codecs.

If you press the Load Defaults or Restore Defaults button in both codecs you'll be at a medium setting that is a pretty close match between the two -- except change Divx from 1-pass (constant bitrate) to 1-pass quality based. This is a constant quality mode where you pick the quality and the codec will use as much bitrate as necessary at each frame to deliver that quality. So you don't know exactly how big the file will turn out. Oh, if you have a multiprocessor or multicore system set Xvid to use as many threads as you have cores (ie, 2 on a Core 2 Duo, Pentium D, or Athon 64 X2). Divx automatically determines how many threads to use.

Both codecs have a default quantizer of 4 when target quantizer mode is selected. I usually use 2 for important videos and 3 for everyday stuff (the higher the quantizer the lower the quality and the smaller the file size). But even 4 is higher quality tham most things you might download from the web. In constant quantizer mode the higher you set the quality settings the smaller the file will be. Maxing out the quality settings will take much longer to encode (several times longer than Balanced or General Purpose) but will usually only reduce the file size by about 10 percent.

Most videos you find on the web have been encoded with a 2-pass variable bitrate. In this mode you pick the size of the file you want (via the bitrate, file size = bitrate * running time) and the codec delivers whatever quality it can for that file size. In this mode, the higher you set the quality settings the better the visual quality will be. Maxing out the quality settings will increase the visual quality by a small amount. It's hard to quantify this but if you consider that the difference between Balanced and Insane quality levels in Divx give around a 10 percent reduction in file size when using constant quantizer mode, then you could use a 10 percent lower bitrate at Insane and achieve the same visual quality as Balanced when in 2-pass VBR mode.

If you ever plan to watch your Divx or Xvid encoded AVI files on a set-top Divx/DVD player you probably want to avoid GMC (Global Motion Compensation) and QPEL (Quarter Pixel). These generally don't make much difference in visual quality but many players will have problems with them.

Some useful links:

LisaB's guide:
http://www.jarnot.com/twiki/bin/view/Public/DVP642LisaBsAVIGuide

Xvid FAQ (somewhat outdated though):
http://forum.doom9.org/showthread.php?s=&threadid=16935

Koepi's Xvid Options Explained:
http://nic.dnsalias.com/XviD_Options_Explained.pdf

[Paultx]

So no one can say for sure this XviD compliant DVD player I'm considering to purchase will play DivX vids?

[SlightFall]

This might blow your mind, but here it goes.

DivX, are you still with me? IS, XviD backwards!

[manono]

This might blow your mind...

I doubt it, since the post to which you're responding is over two years old.