[prev in list] [next in list] [prev in thread] [next in thread] 

List:       linux-video
Subject:    Re: [video4linux] Re: [Fwd: Who has TV cards?]
From:       Alan Cox <alan () cymru ! net>
Date:       1998-08-10 11:21:58
[Download RAW message or body]

>   I will take this opportunity to make some observations about
> the kernel interface though.  Is Alan on this list?  He said

Yep

> something once about the number of clipping rectangles being
> limited to 200 or something like that.  The new extension
> clips the video to the GC's client clipmask so In theory you should
> be able to do things clip the video to a pentagram and have it
> displayed in a window.  I don't know why you'd want to do that,
> but if you did, you'd certainly need more than 200 clip rectangles
> (unless it was a very little pentagram).  Anyhow, for rendering
> into shaped windows and things like that, it might be useful.
> So if the clipping rectangle limit is an arbitrary one, you might
> want to make it a big arbitrary one.

The bigger it gets the more resources it eats. I believe the Zoran
actually takes a bitmask. Nathan Laredo was playing with a bitmask mode
for the bt848 too (it actually has to reduce things to per line lists
of data and holes). To go higher really wamnts the bitmask mode or an API
change where the caller provides a per scan line data set and does the
sorting

>    Hmmm.  I was just going to make a comment about the kernel
> interface not allowing for putting of subareas of the source to 
> the screen, but it looks like there's some stuff in the API 
> about that now.  Anyhow, I stuck a version of the client library

Its not implemented in anything yet

> as soon as I have a sufficient survey of the hardware that supports
> it so that I know what to make the interface look like.

Somewhat messy right now. You may be better off spending time on the
other areas and coming back to it once its all nailed down. Also for cards
that DMA into frame buffer you can capture to an offscreen but in video
memory block of space (in fact for many video card attached devices thats
all you can capture too)

------------
To unsubscribe from this list send mail to majordomo@phunk.org with the
line "unsubscribe video4linux" without the quotes in the body of the
message.

[prev in list] [next in list] [prev in thread] [next in thread]