Is XviD actually "Darker"?

[poochie2]

In every comparison I make XviD always seems to show a little bit darker image than the source and than divx5, is this normal?

[fisix]

if this is true, it could effect the psnr numbers being generated. there should be a way to test this with avisynth and one of the plugins..

[Imperial Llama]

In my experience the brightness has always been the same between XviD, DivX 5 and the original source.

What method are you using to compare the brightness of the videos? If you did it by loading each clip into a separate media player than this is likely to to cause difference between the clips. This is because the first video you load will be rendered using the hardware overlay on your graphics card and the subsequent videos you load will be software rendered. Often the overlay looks a little different from the software mode; on my GeForce2 MX it is quite a bit darker and has a blue hue to it.

If you think this might be causing the differences you are seeing, try loading each clip into VirtualDub as this will avoid using the overlay.

[mf]

An even easier way, is using AVISynth:


srce = AVISource("Source.avi")
xvid = AVISource("XviD.avi")
divx = AVISource("DivX.avi")
blah = Interleave(srce, xvid)
Interleave(blah, divx)

[poochie2]

I simply compare the screenshots I made using acdsee and xvid has always shown me a bit darker image than the source and the divx5 one... try and see... If you want my screenshots I can pass them through email or if you tell me where to upload them!

[communist]

Just set XviDs brightness in the decoder a bit higher :)

[poochie2]

... well, I see that, but why by default doesn't it render the most similar image possible to the source video?

:confused:

[Manao]

poochie2 : try as Imperial Llama said to load both clip in VDub, or interleave them as suggested mf. You'll see that there are no differences between XviD and DivX, and that it's just a problem of brightness settings that differs from one decoder to another when using the overlay.

[poochie2]

I'll try as soon as I can, but, as Imperial Llama said, I didn't use anything but Virtualdubmod... so no problem with hard/soft overlay methods...

:eek:

[Manao]

Well, in that case, errmmm....

I would bet it's DivX 5 fault !!!!! :D

[BoNz1]

Originally posted by Manao
Well, in that case, errmmm....

I would bet it's DivX 5 fault !!!!! :D

Actually, in this case in may very well be DivX5's fault. If you let DivX decode YV12 you will find that it is slightly darker in virtualdubmod as opposed to if you let XviD decode YV12.

[poochie2]

I set DivX to decode itself and ffdshow to decode xvid...

[BoNz1]

No, check in virtualdubmod when you open your avs. If you go to file information it will tell you the decompressor. If it is DivX you will notice the output is noticeably darken then when XviD is the decompressor. As for solving this problem, I guess there are other ways but I just uninstall DivX when it decides to take over :p.

[poochie2]

It says Decompressor = Xvid MPEG 4 Codec !

I tried to solve your math problem... supposing that the sides are a,b,c and the base being a*c, the sides measure a=4 b=6 c=4

Is it correct?

:devil:

[BoNz1]

Ok, then this must not be the problem. BTW for the math question you got the right answer :). It actually came straight off my calc. III final, :)

[poochie2]

When you got another tell me... I like those... anyway at first I didn't get one peculiarity of the problem that makes it solvable, so I built a small app that got the result by brute forcing :D, then I understood it... ;)

[Tuning]

@poochie2,

Well, what is darker when you use FFDShow for both XviD and DivX ? :D

[poochie2]

Wow, nice move... they're both dark... must try the default xvid decoder then!

:rolleyes:

[rkingbo]

I'm not sure it's coder-related or decoder-related, but I do sense those "Darker" image when encoding med/low bitrate movies(I'm using the latest ffdshow). Anyway, I settle this by using two filters - MSharpen & Tweak.

Here's the sample -

original:

http://www.excel-hifi.com/tools/xvid.jpg

MSharpen & Tweak:

http://www.excel-hifi.com/tools/xvid+tweak+ms.JPG

(Visually closer to the source)

[leowong1]

yea, i have this experience too, my encode is always darker than the orginal brightness in virtualdub

[DanielSun]

Yes,I think that is true.I often have my quick encode using GKnot.
,sometimes with VDub .The result seems always darker.I did not use any filters,but only crop,lanzoc resize,sometimes undot.

I simply compare them with my eyes,and it is definitly darker!

[Koepi]

Originally posted by BoNz1
No, check in virtualdubmod when you open your avs. If you go to file information it will tell you the decompressor. If it is DivX you will notice the output is noticeably darken then when XviD is the decompressor. As for solving this problem, I guess there are other ways but I just uninstall DivX when it decides to take over :p.

Since you're not reading the whole thread, here repeated the answer to your "darkness problems".

Koepi

[poochie2]

Originally posted by Koepi
Since you're not reading the whole thread, here repeated the answer to your "darkness problems".

Koepi

Not only: as it has been pointed out, by default ffdshow renders a darker image indipendently from the source being divx5 or xvid! :)