Xgl and v4l2

[Matthias Hopf]

On Mar 06, 06 00:38:15 +0100, Piotr Maksymiuk wrote:
> Now i use it day to day except for one thing. The most crucial part to
> me - v4l seems currently to be broken with just about any v4l2
> viewing/recording app. Since i already sent an email to David, ill just
> paste my findings here.

This is odd, as Xgl does not support PutVideo, so all data has to be
pushed by the client. This is the same mechanism as used in video
players, and that has been tested a lot - with no problems.

Note that if you're using a copositing manager and don't have -accel
xv:pbuffer specified you get software conversion code - which isn't
really tested much.

> [snip]there seems to be a nasty bug when using v4l2 and xvideo
> together (think tvtime, xawtv and tuner cards). First off, im using
> 2.6.15, X.org 7 (modular), Mesa 6.5 alpha, and fglrx 8.8.25 (and yes, on
> display :1) and with a Radeon 9500Pro 64MB. 

I'm not entirely sure, but the Radeon 9500Pro should be able to use the
fragment program based conversion code. Unfortunately, Xgl doesn't have
a log file or even verbose mode yet.

> Also, one more thing. When using v4l2 as input and xv as output MAJORLY
> slows down Xgl. Usually it runs super smooth, but when using this

Sounds like you hit the software conversion path.

> combination it seems VERY sluggish, about 3-4 fps. When using grabimage
> in xawtv everything still runs smoothly.

I still do not completely understand what the applications are doing.
*Only* a grabimage approach is to work on Xgl, direct port connection
*cannot* work and the necessary properties are not exported by Xgl.

Matthias

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