[MPlayer-users] Re: divx 6

[Corey Hickey]

Matthias Wieser wrote:
> Am Donnerstag, 20. April 2006 21:00 schrieb Corey Hickey:
>> Szabolcs Nagy wrote:
>>> hello
>>>
>>> is there any way to use the linux divx 6 binary codec with mencoder ?
>>> http://labs.divx.com/DivXLinuxCodec
>> No, though if someone were to add support it would be useful for testing
>> and comparison.
>>
>> In any case, you'll probably get better performance and/or quality by
>> using XviD or libavcodec MPEG-4, both of which are well-supported in
>> mencoder.
> 
> Xvid and DivX 6.1 seem to be much faster at better quality than libavcodec.
> http://www.doom9.org/index.html?/codecs-main-105-1.htm

That depends, and a few things have changed since the Doom9 comparison.

1. Lavc has slightly better overall encoding than it used to.

2. XviD used to avoid B-frames where they would be detrimental much 
better than lavc. With vb_strategy=2, lavc does just as well, though 
much more slowly.

3. Lavc places I-frames slightly better than before, with sc_factor=6.

4. XviD's ratecontrol adapts to motion much better. Now, lavc can use 
XviD ratecontrol internally. Alternatively, a more XviD-like ratecontrol 
equation for lavc is vrc_eq=(tex+10^8*mcVar)^0.6


At this point, taking the above considerations into account, lavc will 
produce video that is nearly indistinguishable from that encoded by XviD 
(and certainly looks just as good), but at a much slower speed.

...there's a bit more, though: I haven't mentioned qns. qns=2 makes 
sharp high-contrast edges in encoded material look much better, but 
slows down the encoding process dramatically.


So, here's my current summary view on all this:

- by default, lavc encodes much faster but looks somewhat worse than XviD
- if you enable most high-quality options, lavc can look as good as
XviD but encodes much more slowly
- if you enable qns as well, lavc can look better than XviD but encodes 
even more slowly


For the lay encoder, XviD is probably a better choice. If you need 
either extreme speed or the very best quality, though, use lavc and tune 
it for whichever you need.

Just for the sake of mentioning it, x264 gives even better quality, but 
that's a different comparison.


You may have noticed that I haven't mentioned DivX 6. That's because 
I've never personally tested it. If the Doom9 comparison is accurate and 
still current enough with respect to DivX 6, however, DivX is 
almost-as-good-as-XviD and almost-as-fast-as-XviD, which means XviD is 
better in both aspects at once and lavc can be even better in either 
aspect but not in both at the same time.

-Corey