Subject: [V4L] support for Xv ?
From: Chris Malley <cmalley@xxxxxxxxxxxxxxx>
Date: Wed, 16 Aug 2000 09:10:21 -0600
I've installed X 4.0.1, and I'm attempting to play around
with Xv (the X video extension). The X driver documentation
is pretty terse, and doesn't say which drivers contain Xv
support. Does anyone know where I can find this information?
I realize that I can call XvQueryExtension, but I'd prefer
to know before I purchase the graphics card. Thanks.
Chris Malley Email: cmalley@xxxxxxxxxxxxxxx
Interact-TV Web: http://www.interact-tv.com
2503 Walnut Street Suite 100 Phone: 720-406-9399
Boulder, CO 80302 USA FAX: 720-406-8424
Subject: Re: [V4L] support for Xv ?
From: "bharat tewari" <bharat.tewari@xxxxxxxxx>
Date: Wed, 16 Aug 2000 20:38:49 +0530
i know that matrox, i810 and ati cards have Xv support, the extent of the
support may vary but all of them support XvImages().
> I've installed X 4.0.1, and I'm attempting to play around
> with Xv (the X video extension). The X driver documentation
> is pretty terse, and doesn't say which drivers contain Xv
> support. Does anyone know where I can find this information?
> I realize that I can call XvQueryExtension, but I'd prefer
> to know before I purchase the graphics card. Thanks.
> Chris Malley Email: cmalley@xxxxxxxxxxxxxxx
> Interact-TV Web: http://www.interact-tv.com
> 2503 Walnut Street Suite 100 Phone: 720-406-9399
> Boulder, CO 80302 USA FAX: 720-406-8424
> Video4linux-list mailing list
Subject: Re: [V4L] support for Xv ?
From: kraxel@xxxxxxxxxxxxxxxxxxxxx (Gerd Knorr)
Date: 16 Aug 2000 17:28:12 GMT
Organization: Strusel 007
User-agent: slrn/0.9.6.2 (Linux)
bharat tewari wrote:
> i know that matrox, i810 and ati cards have Xv support, the extent of the
> support may vary but all of them support XvImages().
Depends on what exactly you want to do. The tree ones mentioned above support
yuv pixmaps + hardware color space conversion/scaling for pixmaps passed by
the application. Using Xv for video display (using the v4l module) and writing
the video stream directly to the visible framebuffer should work with all
drivers. Hardware scaled video works with matrox g200/g400 only as far I know,
but I expect other drivers follow quickly.
Below is a README I've written for the next xawtv release.
XFree86 4.0 tips & tricks
Release 4.0 has DGA turned off by default. You'll have turn it on
in XF86Config, otherwise v4l-conf will not work correctly. It should
work for most cards this way, althrouth some drivers don't handle DGA
correctly in 4.0 (that's why it is off...)
XFree86 4.0 comes with a new X11 extention for video support. The
X-Server will handle the grabber board then, not xawtv. This has the
advantage that the X-Server knows about the video. Window moves can
be handled without redraw problems. The refresh triggered by xawtv
to fix it isn't required any more. It is possible to use the video
scalers of modern graphics boards (see below).
To use Xvideo you have to load the video4linux module into the X-Server.
Just adding 'Load "v4l"' to the Modules section of XF86Config will do.
You have to make sure xawtv is compiled on a box with with XFree86 4.0
installed. xawtv needs the new client libraries for Xvideo support.
using hardware scaling
Starting with XFree86 4.0.1 the Xvideo extention supports hardware-scaled
video, i.e. the video isn't written directly to the visible area of the
video memory. Instead the bt848 hardware writes yuv data to offscreen
memory. The graphic card's video scaler does color space conversion and
video scaling. This way fullscreen video works in 1024x768 (and greater)
without a black border because we are not limited to the maximum size
supported by the bt848 hardware any more.
As this is very new stuff not all drivers support video scaling yet.
Right now it works with the mga driver (matrox G200+G400) only.
You also need a bttv version newer than 0.7.16 (the 2.2.x kernel version
is /way/ to old, kernel 2.4.x is fine). If both bttv driver and xfree86
gfx driver support it, xfree86's video4linux driver will use hardware
capturing images/video doesn't work if xawtv runs using the Xvideo
extention. With the '-noxv' switch Xvideo can be disabled.