[directfb-users] Re: pixelformat on cle266 overlay

[Selwyn Tang <selwyn@hectrix.com>]

On 11/14/2003 04:46 PM, Ville Syrjälä wrote:
> Set the buffermode to backvideo.

Thanks! This eliminates the flickering. What's interesting is that in
df_window.c, it first checks the card caps for alphachannel and
coloralpha. If either one is unavailable, it sets buffermode to
backsystem. Else, it use the default mode, which is, in my case,
frontonly. For my cle266, both alphachannel and coloralpha are available
for both layers (primary and cle266 overlay), so it uses the default
frontonly. The flickering only occurs on the overlay, but not the primary.

I don't understand why it uses backsystem when either alpha things is
unavailabe.

> YUV support is probably the number one reason for using overlays. Another
> good reason is hw scaling.

AFAIK, there are two video input ports (VIP) and one bt.656 on cle266.
So I guess the overlay is for these video capture stuffs. If so, I think
I should just keep using the primary layer only, since when I get the
overlay layer, it just blanks out the screen and doesn't seem to be
alpha blended with the primary layer. What do you think?

Selwyn



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