software video capture by replaying X requests slowly
Amir Michail
We have been working on DRT, a design recovery tool
for X apps.
http://www.cse.unsw.edu.au/~drt
http://www.cse.unsw.edu.au/~drt/screenshot
We would like to build a new version DRT II which supports
a much wider range of X apps, including real-time arcade games
and flight simulators.
You can find a proposal here:
http://www.cse.unsw.edu.au/~cs3141/proposal.pdf
In DRT II, we will need to capture a video of the X app while it is running.
Basically, we will describe interesting "events" by video snippets
showing what heppened during that event.
Real-time video capture doesn't appear possible using software only
methods with today's hardware.
So it seems perhaps we could record all the X requests and replay them
back slowly enough to construct a video. Is that the easiest way
to replay the app execution from time [t1,t2] (without showing anything before
time t1)?
It seems that replaying X input events is not enough since the app may
update the display at regular intervals using a timer-based system unrelated
to X.
Any tips would be greatly appreciated.
Amir
Michel Bardiaux
> Hi,
>
> We have been working on DRT, a design recovery tool
> for X apps.
>
> http://www.cse.unsw.edu.au/~drt
> http://www.cse.unsw.edu.au/~drt/screenshot
>
> We would like to build a new version DRT II which supports
> a much wider range of X apps, including real-time arcade games
> and flight simulators.
>
> You can find a proposal here:
>
> http://www.cse.unsw.edu.au/~cs3141/proposal.pdf
>
> In DRT II, we will need to capture a video of the X app while it is running.
> Basically, we will describe interesting "events" by video snippets
> showing what heppened during that event.
>
> Real-time video capture doesn't appear possible using software only
> methods with today's hardware.
Maybe you dismiss that possibility a bit too quickly. What trials did
you do?
>
> So it seems perhaps we could record all the X requests and replay them
> back slowly enough to construct a video. Is that the easiest way
> to replay the app execution from time [t1,t2] (without showing anything before
> time t1)?
>
> It seems that replaying X input events is not enough since the app may
> update the display at regular intervals using a timer-based system unrelated
> to X.
>
> Any tips would be greatly appreciated.
>
> Amir
--
Michel Bardiaux
Peaktime Belgium S.A. Bd. du Souverain, 191 B-1160 Bruxelles
Tel : +32 2 790.29.41
Amir Michail
> Amir Michail wrote:
> > Hi,
> >
> > We have been working on DRT, a design recovery tool
> > for X apps.
> >
> > http://www.cse.unsw.edu.au/~drt
> > http://www.cse.unsw.edu.au/~drt/screenshot
> >
> > We would like to build a new version DRT II which supports
> > a much wider range of X apps, including real-time arcade games
> > and flight simulators.
> >
> > You can find a proposal here:
> >
> > http://www.cse.unsw.edu.au/~cs3141/proposal.pdf
> >
> > In DRT II, we will need to capture a video of the X app while it is running.
> > Basically, we will describe interesting "events" by video snippets
> > showing what heppened during that event.
> >
> > Real-time video capture doesn't appear possible using software only
> > methods with today's hardware.
>
> Maybe you dismiss that possibility a bit too quickly. What trials did
> you do?
Hi,
DRT I takes a single screenshot before and after each user action and
already this process is the slowest part of the system.
In a real-time game, you may wish to take 10 or more screenshots a
second which is way more than most computers can handle I believe --
particularly at high resolutions.
However, I have noticed that I can play some real-time X games over a
network without too much of a slow down, so persumably it is possible
to record their X requests without slowing down the apps too much.
However, I have been told that replaying X requests is not a simple
matter. My knowledge of X is very limited so I don't really know the
issues involved.
Perhaps there is a better way to do this.
Amir
Karl H. Beckers
> [...]
> Real-time video capture doesn't appear possible using software only
> methods with today's hardware.
Hi,
dunno if this serves your needs, but you might want to have a peek
at http://www.sourceforge.net/projects/xvidcap
Cheers,
Karl.
Amir Michail
Hi,
Yes, one of the students on the project recommended xvidcap and we
ended up using it in DRT/Video. I'm amazed that xvidcap works so
well.
Amir
P.S. You can find out more about DRT/Video here:
http://www.cse.unsw.edu.au/~drt/screenshot
http://www.cse.unsw.edu.au/~amichail/drtvideo.pdf
>
> Cheers,
>
> Karl.