DivX Pro guides inconsistency?

[hdi20]

Guides for version 5.1.1. state: "...you can enable GMC (and QPel as well if you want - I'm still not convinced it really contributes to a good encoding session but you may want to check it out and see if the results please you) and by pressing Finish you can save these settings."

On the other hand guides for version 5.2.1. suggest the following: "...enable QPel by checking Use Quarter Pixel. I would not suggest activating GMC. So far, I'm unconvinced that this feature really contributes towards quality of the output. Finally press Finish you can save these settings."

As you can see old guides suggest using GMC but not QPel, new guides do just the opposite. Has DivX codec really changed that much or is one of the guides faulty?
Thx

[Sharktooth]

Well i would follow the 5.2.1 guide.
DivX GMC is useless coz it uses only 1 warp point (use search for more details) and IMHO qpel rises the perceived video quality (but you may not like it).
Be aware qpel may not work in some standalone players.

[stephanV]

the first one is faulty

GMC (regardless of how many warppoints) seems to give a rather small advantage over no GMC, is slower and incompatible with most hardware devices. so unless you are an absolute quality freak, i wouldnt bother with it.

i always wonder why there seems to be no GMC in H264...

[Doom9]

You kept the old guides?

Perhaps you can tell my mirror admins about the changes I make in the guides ;)

Seriously, the QPel comment comes back from DivX5.0... in the meantime I suppose QPel has improved because I no longer dislike it (independent of the codec).. whereas the usefulnes of GMC is really debateable (it's also not included in the AVC standard anymore.. QPel still is). So, QPel yes, GMC no.

And as far as standalones go, if yours can't do QPel, buy a new one ;) Chipsets that can't handle QPel are crappy anyways.

[LordRPI]

Originally posted by stephanV
the first one is faulty

GMC (regardless of how many warppoints) seems to give a rather small advantage over no GMC, is slower and incompatible with most hardware devices. so unless you are an absolute quality freak, i wouldnt bother with it.

i always wonder why there seems to be no GMC in H264...

That's been the consensus with quite a few sources. GMC, while good in theory, is rarely used in reality (especially with one warp point). There are other aspects of video coding to optimize that yield better results while using a comparable amount of processor time. Bridging Amdahl's law into software runtime, this would explain the lack of GMC in newer codecs.

[Shinigami-Sama]

I was wndering
if there anything that could giver very specfice information in Qpel and gmc
the only thinggs I've managed to find out is that they "apper" to raise visual quality but there seems to be no realy informatoin on it...
but why even use a standalnoe player?
just buy a $200 computer and get tv out and wireles keyboard/mouse that player everything :)
and you don;t have to worry about compatablity ;)
-edit-
hmm that was a bit of topic
maybe no-one realy knows what it does except the coders so that caused the discpenicy
or it;s based on opion...

[fewtch]

Originally posted by Shingami-Sama
but why even use a standalnoe player?
just buy a $200 computer and get tv out and wireles keyboard/mouse that player everything :)
and you don;t have to worry about compatablity ;)

Umm, because you can get a standalone for $60 or so ($60 < $200) that has zero fan noise, has a remote control and doesn't look funny sitting next to the TV set... :p

Actually, compatibility is hardly a worry; very few seem to use GMC or Qpel these days. And remember, we're backing up our own DVD's here... :D

P.S. the last time I used GMC/Qpel, it was an experiment to fit a 150 min. movie onto a 700MB CD-R. Turned out pretty well (with postprocessing it looked very nice), but it could have been the other optimizations like VHQ mode 4 and Lumi masking...

[Shinigami-Sama]

I guess you;re all used ot usd not cdn here
so I'll retry this
standalones are about 150-200 in cdn for a midrange one
so if I can pick up a used comp with everything I need for $200
which do you think is hte beter deal?
and you can put hte comp behind something like a disk shelf :p
and you can pick up a pr remote for about 2-30 up here
so I fail to see the point of a standalone

[jggimi]

Let's not argue over standalone vs. computer; it is not helpful discussion since it has nothing to do with the questions at hand, and is likely to only devolve into a flame war.

Above, Shingami-Sama asked:

...f there anything that could giver very specfice information in Qpel and gmc the only thinggs I've managed to find out is that they "apper" to raise visual quality but there seems to be no realy informatoin on it...

DivXNetworks has a terrific guide that describes, in detail, every MPEG-4 ASP feature used in DivX, from Quantizers and Motion Vectors to Macroblocks and Matrices. Quarter Pixel and Generalized Motion Control (Qpel and GMC) are also discussed. See http://www.divx.com/divx/divxpro/guides/.