Mod HQ

[jbbank]

Hi everyone... I've just begun experimenting with the XViD codec. I was always a big fan of SBC, but it seems like XViD has made enough progress in the last year or and I'm beginning to like it.

So far, I've been using H.263 and Modulated for 1st and 2nd pass respectively. What is Mod HQ? I've tried using it and haven't really found a big difference. Are there certain situations where it would be beneficial to use that instead?

Thanks

[Kyo]

Is a type of modulated quantizers but instead of the normal this can make that for quant < 3 the H.263 Matrix is used and for quant > 3 the MPEG. This can bring better image with low noise in the low quants(MPEG matrix. behaviour).

[Kramerica]

Is it ok to run Mod HQ during both passes? I remember reading on the Doom9 guide that with the normal Modulated setting, you needed to run the first pass with H.263. I have since run some with Mod HQ during both passes and the results came out fine. Is it actually using Mod HQ for both of these passes?

Kramerica

[scorchED]

in first passes quant 2 is used - so if you choose ModHQ for first pass every frame will be calculated with h263.

[kilg0r3]

well i don't know. you could download debugview and run it during both passes. then you can see what the codec does in the output window

cheers

[iago]

@Kramerica

Imho it will be better to use MPEG quantization type for the first pass if you want to use ModHQ for the second pass.

regards,
iago

[Kramerica]

Thanks for the tip iago. When do you guys think it best to use Mod HQ? I am finding I like the results for my one cd rips, but am using MPEG still for the normal 2 cd rips.

[Kramerica]

I recently did two encodes, one using Mod HQ/Mod HQ and the other using MPEG/Mod HQ. Both encodes turned out identical videos. This leads me to conclude that using Mod HQ during the first pass actually enacts MPEG, not H.263.

[MaTTeR]

Originally posted by Kramerica
This leads me to conclude that using Mod HQ during the first pass actually enacts MPEG, not H.263.

I also use the ModHQ mode quiet often with nice results and I've noticed the same thing on first pass. In fact, using the standard modualted mode on the first pass also appears to use MPEG quants.

[yaz]

hi all !

i dunno xactly how xvid decides on 1st pass mod, but using mpeg for that seems to be quite logica. before 1st pass there's no info about where to use the mpeg & where the h263 quant matrix, so (imho) it's impossible to use any kinda 'mixed' mod for that. it prompts that xvid must decide on which to use if a 'mixed' mod is selected for that. further, using mpeg for getting this info gives more flexibility to the codec maintaining the final size on 2nd pass.
ok, it's only my logic, it's possible that xvid use another one :-)) personally i always use mpeg in the 1st pass if i want to use mpeg/mod/hq in the 2nd. sometimes i used also this for h263 2nd pass (simply i forgot to switch it:-) & there was no problem. however, it's just experience not suggestion

y

[Asmodian]

DebugView indicated xvid uses MPEG quants on the first pass when doing a two pass encode with ModHQ quants set for both passes.:)
I am using XviD-12102002-1 from Koepi

[kempodragon]

Strange, I got the exact opposite. During my first pass, Debugview showed H.263 being used with Mod HQ. Any ideas why?

[MaTTeR]

Originally posted by kempodragon
Strange, I got the exact opposite. During my first pass, Debugview showed H.263 being used with Mod HQ. Any ideas why?

In all the encodes I've done with ModHQ I've never seen H.263 show in the first pass. What build are you using?

[kempodragon]

Went back and looked at the log file and realized I'd been looking second pass. :) It does indeed use MPEG quantizers for the first pass.