DivX MPEG 4...Low-Motion and Fast-Motion...What's the differ

[wings123]

Anyone help me out?

[LighthouseJ]

I think it's the different algorithms it uses to encode with. Depending on if your move has a low motion or high motion, it uses different optimization techniques.

[Dolphine]

*LighthouseJ, yeah is there in short more or less. The main difference between them is really they way the 2 codecs optimise the video signal that is coming into them. The fast motion codec was meant to be used when converting movies where the background scene changes often (sci-fi, action, etc) ..more or less where the movie frames rapidly change from one scene to another. The low motion codec was created to help encode movies that had very little background change - or movies where there wasn't much if any action (drama's, sitcoms etc).

Both codecs were optimized for the movies they were in particular, meant to encode, however if you do a few tests you will see that the fast motion codec in actual fact is very poor - even when encoding "fast" movies - this will be indicated by the pixelation (blocking) that you see when a very fast moving scene appears - even putting the codec to a higher bitrate doesn't give it that much more quality.

The low motion codec however is very good, at a low bitrate it does drama etc stuff quite well, but put the bitrate to something like 2600 and you can then even use it to do fast action type movies and the quality will be absolutely great, much better than the fast motion codec - although mind you, that at this bitrate level an avi could well be in the region of 1.1 - 1.4 GB large.

If you need to use one - I say go with the low motion codec - put the bitrate to something really high (2500-3000) and you will have a nice high quality divx file!

[suspect]

The low motion bitrate bar sets the average total bitrate of the divx file. Fast motion sets the Maximum bitrate of the divx file, the average bitrate is locked at 350k.