fast and low motion

[kakomu]

I've noticed in just about everyone Nandub settings, you set the codec selction sliders all the way up to 300, meaning that the Fast motion codec isn't used. However, if the fast motion codec was designed to be better at fast motion video, wouldn't it be wiser to set the sliders to around 250, 200 or even as low as 150? If not, can someone tell me exactly why they would do so?

PS Yes i already read the Doom9 nandub guide, unfortunately it really doesn't go into detail about it, and through my own tests, I found the fast motion codec to be proficient in areas where the Low motion codec tripped and fell (this is Vdub pure LM of FM, not Nandub).

[manono]

Hi-

As I understand it, it's the same as the low motion codec except that it begins with DRF 5. So it has DRF 5-31, and the low motion codec has DRF 2-31. Low motion can do everything that fast motion can. There's no need to adjust the sliders down from 300. If you need the higher DRFs, low motion can do it just as well.

Also, I'd say that using VDub for DivX3.11 encoding is by no means optimal. Use the 2 pass in Nandub-SBC. If you're not sure of all the settings, then let GKnot do it for you.

[kakomu]

Obviously Nandub is optimal, however, I was wondering why if Fastmotion seemed to provide better results in fast motion sequences, why not use it in nandub encoding.

[NeVeRLiFt]

Originally posted by manono
Hi-

As I understand it, it's the same as the low motion codec except that it begins with DRF 5. So it has DRF 5-31, and the low motion codec has DRF 2-31. Low motion can do everything that fast motion can. There's no need to adjust the sliders down from 300. If you need the higher DRFs, low motion can do it just as well.




;)

[manono]

Hi-

I was wondering why if Fastmotion seemed to provide better results in fast motion sequences, why not use it in nandub encoding.

Because you have no control over the DRFs assigned when using one pass in VDub the way you would by using the first pass stats file to encode the 2nd pass in Nandub. For example, the fast motion encode could have done the whole thing in your VDub test at DRF 5 depending on the bit rate you set. Using the low motion codec might have given you DRF 2 and 3 with the static scenes (which I'm sure looked much better), while giving you DRF 7 and 8 (or 10, or 15) in the action scenes. If you're curious about this (although I have no idea why you should be-you're just beating a dead horse), then encode a small section with DebugView (http://www.sysinternals.com/ntw2k/freeware/debugview.shtml) running, so you can compare the DRFs. What I'm saying is that your 1 pass test in VDub didn't prove anything about FM being better than LM. You don't know anything about what DRFs were actually assigned in the 2 tests.

Since Fast Motion uses DRF 5 and up, if you're allowing enough bit rate to begin with, and you disable the curve compression and lumi compression stuff, your action scenes should look as good as your static scenes when encoding in Nandub-SBC. If you are bitrate constrained, and you use all the "psychovisual" stuff, and your DRFs in the action scenes jump to 5 and above, there's still no point in moving the sliders to allow the use of the FM codec, as the LM codec will also be switching to the same DRfs. I'll leave the last word to Koepi and his thorough Nandub Options Explained (http://mitglied.lycos.de/koepi/nandub_options_explained.html):
4.3 Fast/Low Motion sliders:

If these sliders are set to 300 then the codec-switching between high-motion DivX;-) and low-motion-DivX;-) is disabled. (in fact turning the fast-motion-slider to 300 will suffice.) Using lower values will switch the codecs at the given "motion points", e.g. fast motion at 285 and low-motion at 265 will switch to DivX;-) high motion when motion detected in the first pass goes over 285 and will fall back to DivX;-) low motion when dropping below motion of 265 again. Don't use codec switching. It degrades quality at the high-motion scenes unneccessary and introduces problems with dropped frames and/or freeze frames - instead I use the bitrate reservoir modulation (see below) and the main DRFs. The high-motion codec is in fact nearly the same as the low-motion-codec (but has a better scene change detection core) with hardcoded DRFs from 5x to 16x. So you can emulate it by setting the DRFs according to that.

[kakomu]

Ok thanks for the reply.

[^^-+I4004+-^^]

>I found the fast motion codec to be proficient in areas where the Low motion codec tripped and fell (this is Vdub pure LM of FM, not Nandub).


there's one more thing,if you REALLY (hehe) like one-pass:
NDub can do 1pass but with total control over DRF's and
Gauge.....(i regard those as most important divx parameters)
this works quite well even in fastrepak mode of ND:
i've set DRF2-7(still testing,probably it'll be 2-5 or 2-8
for less demanding stuff) and KF's to 2-16.....(gauge 40-100 as for 2 cdrips which i always do...) and frameserved from avs.......

everything is fine,filesize predictibility too....
(some advanced functions are missing in one pass (endcredits,curve compr.) but who cares.....i just solved problem of poor hi-motion scenes that existed with 320.......)

oh,and yeah,btw. divx320 was used for this test in ND,and all worked as i expected (ie. fine)..

btw. just one side note:i've concluded that "crisp-sharp" seting is nothing more than DRF setting too:
try encoding hires on lobitrate and slider towards smooth.....you have much more ugly blocks,and much higher average values for DRF's

same hires video on same bitrate but his time "crispness" much higher
gives nicer video with less blocks,and less average DRF value.....

so,crisp-smooth is just setting the codec so it can save bitrate (higher DRF's=image destruction) on "smoother" and do opposite for crisper settings..
(but even on "100" still fast motion scenes will get too high DRF's in one pass+VD...)

so for total control use ND in any mode u wish.......
and fastmotion codec is unacceptable anyhow....
(still scenes with min DRF 5? not good...)

cheers
Ivo