Strange problem with Koepi XviD - yellow dots!

[Atlantis]

http://perso.club-internet.fr/willow/Temp_Problem.jpg

I recently noticed something strange. I have Koepi XviD the oct 4 stable version. When I open a XviD file in VirtualDub (VD) the picture have those yellow dots seen in the right picture. I have also tried the Jan 15 build and it is a continous yellow line from top to bottom instead of dots.

The strange part is that when I open the same file in a simple one line avisynth script and open that avs file in VD, I don’t see any yellow artifacts! It's the picture on the left!

This is a problem with the XviD because I don’t get those with any other codecs or Divx. Also if I do a FourCC change and open the same file as Divx 5.0.2 in VD, I don’t get that yellow dots, so the source is OK.

Try it yourself. Just open any Xvid files in VD and copy a source frame and zoom in. Preferably a white background.

[Atlantis]

Update, I just tried Nic XviD build Dec 23 and it gives a straight yellow line also like the latest Koepi.

[-h]

I believe that's a bug in XviD's conversion to RGB. When you load the video via Avisynth, XviD decodes in YUY2 and then Avisynth's RGB conversion feeds the video to VDub, so the bug doesn't appear.

There's nothing wrong with the video, just the way XviD is displaying it in VDub. If you decode it in a YUY2/YV12 capable player, the dots won't appear.

I thought this was an old bug and is fixed now..

-h

[Atlantis]

Thanks –h, that’s a very convincing explanation. I have another question. I did the same test with TMPGEnc and I got the exact same results as VD. Meaning yellow artifacts when opening directly and no yellow artifacts when opening the avs. My question is again why? Since TMPGEnc encodes MPEG and works with YUV why it still gives the yellow artifacts? Doesn’t TMPGEnc open files in YUV when possible?

[Koepi]

TMPEGenc works in RGB when opening avis.

[Atlantis]

Ah OK! So let me get this right. If I want to get a decent correct result with opening a XviD file in a program I always have to use an avs script, right? (talking about encoding it, not playback.)

[Koepi]

To be on the safe side, until the bug is fixed, yes.

[Atlantis]

Now that I think of it again, or to do a FourCC change and use Divx.

Would I get the same result (in decoding) if I open it as Divx in VD or native XviD in avs and then VD? Which method would be the best or right?

[Koepi]

Hello? This isn't a chat. Please think first, post then.

XviD has features that aren't decoded properly by DivX, so I strongly advise against that.

Koepi

[Atlantis]

Thanks. I’m sorry if I offended you. Please feel free not to respond! I see nothing wrong with my post and what I did, and I will do it again in the future. It’s a forum and anyone can ask a legitimate question. That’s what forums are about. People can simply ignore the topics they don’t like!

[Koepi]

It's not about that you ask, it's the frequency. It's good to see that you actually _think_ about things, but instead of bringing the thought to it's end, you immediatly ask again (that's my impression).

There's no offense taken, I just wanted to remind you that it may start wasting someone's nerves if he answers one question and gets occupied by the next question immediatly. (Like in a chat. But if I join a chat i expect exactly that to happen - here i don't ;) )


Regards
Koepi

[Atlantis]

OK, I feel better now. I have to say that anytime I ask a question (or anybody else!) (in any forum!) of course it’s not directed to a single person but to the whole forum and anyone who is interested to answer it.

[NeVeRLiFt]

/me hands Koepi a blue valium :D

[Adam_H]

There's nothing wrong with the video, just the way XviD is displaying it in VDub. If you decode it in a YUY2/YV12 capable player, the dots won't appear.

I have the same problem as Atlantis (yellow dots on left side, horizontally), but they appear not just in VirtualDub, but playback as well (as yellow stripes actually).

Some tests I did:
Player: BSPlayer 086.493 (my main player), Zoomplayer 3.00b5, MV2Player 0.7a
Movie 1: DivX 5.02 encode
DivX 5.02 playback: no yellow stripes
ffdshow 2003-01-03 playback: yellow stripes
Movie 2: XviD 2002-12-03 Koepi encode
XviD 2002-12-03 playback: yellow stripes
ffdshow 2003-01-03 playback: yellow stripes
DivX 5.02 playback (after FourCC change): no yellow stripes
Both movies are reported YV12 colorspace by ffdshow and BSPlayer.

System: AMD Tbird 1200, Win98SE, DirectX 8.1

Anyone have any idea why this happens?

[Koepi]

Adam,

it's still a bug in XviD's colour space conversion MMX routines.
That didn't change for over a year, and most likely won't disappear too fast ;)

Regards
Koepi

[Adam_H]

Koepi,

thanks for the quick reply. I was wondering though, about -h saying that it shouldn't be visible in playback.
I was reading that something is being worked on ffdshow's colorspace routines, so I'm hoping :)