YUY2-Output

[WarpEnterprises]

Can someone explain how avisynth displays the color format to the calling application?
AFAIK every AVI has a FOURCC code which indicates the codec to be used.
Ok, when Avisynth outputs RGB no codec is needed.

But what if the output is YUY2?

There seems to be a definition for a default codec on every system, which is called.
And the behaviour of VD and e.g. TMPG is different (on my system there is a YUY2 codec coming from my capture card?, 4cc is YUY2. This one doesn't open AVS correctly, there are some weak vertical color bars. This is NOT visible in VD, but in TMPG.)
And what about the "force RGB output" thing?
(would be good to add an explanation to docu...)

[dividee]

I don't understand this thing completely; looking in avisynth sources there are two functions which returns a 4CC; both returns "YUY2" for YUY2 but one returns "DIB " and the other 0 for RGB.
Virtualdub recognize the 4CC of YUY2 and has its own routines to open it, it doesn't rely on an external codec.

[WarpEnterprises]

Then could it be that fourcc YUY2 intructs windows to take the default YUY2-codec?
This is quite annoying to deal with because when testing I (and for sure many others) use VD which as you wrote takes its own routine and works (as usual) fine.
Then you go and e.g. encode it and there are some more or less visible diffs... :(

[dividee]

Look in that thread:
http://forum.doom9.org/showthread.php?s=&threadid=27932
and try the huffyuv thing.
Maybe I should make that thread a sticky ?