Re: [Celestia-developers] Ogg/Theora Capture in Linux.

[Selden E B. Jr <se...@le...>]

> Le mercredi 26 juillet 2006 06:45, Pat Suwalski a =E9crit=A0:
> > 1) Aspect Ratio
> >
> > I don't understand what the code does with the user's selected as=
pect
> > ratio. No matter what I choose, I need to select "Square" in my v=
arious
> > video players to get it looking right. "Auto" never shows the cor=
rect
> > aspect. I suggest we make the aspect always be what the aspect of=
 the GL
> > area is, and find a way to make the ratio as written in the strea=
m be
> > correct. It is far too confusing and non-user-oriented at the mom=
ent.

> The solution I found here is to not set the aspect ratio in the str=
eam.
> Players then use square pixels which is what we want.

Don't forget that digital TV (e.g. DVD and HDTV) resolutions require
 non-square pixels.

> William pointed out ( http://www.shatters.net/forum/viewtopic.php?t=
=3D8953 )
> that not setting the aspect ratio might be problematic for some oth=
er uses
> like burning to DVD. In the KDE interface I made it optional, see t=
he last
> argument of OggTheoraCapture::start.

It might be appropriate to include the standard HDTV resolutions
as specific options so that the user doesn't have to know their
actual aspect ratios and resolutions. Many people don't.

> > 2) Framerate Limiting
> >
> > Framerate limiting in Celestia has been brought up before, most n=
otably
> > in the excellent Mac developer article about optimizing Celestia =
[1].
> > With this kind of video capturing it is now an important factor. =
By
> > default, we should not go higher than the user's monitor's refres=
h rate.
> > When capturing video, we should not go higher than the FPS rate
> > specified by the user. I get a fairly massive performance hit whe=
n
> > capturing. Has anyone written frame-limiting code before? It shou=
ld be
> > fairly trivial, but important.

> Agreed.

> > 3) Rec/Stop UI
> >
> > Using keybindings for F11/F12 is precarious in GNOME. Not a huge =
deal,
> > but I was thinking about writing a cool little translucent overla=
y
> > widget that would go over the top-left corner of the GL area and =
provide
> > Rec/Stop functionality. Something similar to what PowerPoint does=
 in the
> > lower-left. Otherwise, just a menu. Any comments?

> Check out the Windows version, the capture size is actually not bas=
ed on the
> GL widget size and you get a frame around the captured area with va=
rious
> information (recording/paused, frame rate, etc...). For KDE, I used=
 the
> status bar and the capture dialog includes instructions on how to s=
tart/pause
> and stop the recording.

> http://celestia.teyssier.org/screenshots/celestia-theora-capture-dl=
g.png
> http://celestia.teyssier.org/screenshots/celestia-theora-capture.pn=
g

The video control panel looks good.
Hopefully some of the image size options will cause the Aspect Ratio
field to be ineffective or at least to have an appropriate default
value.

Also, many people have reported problems with the Windows video captu=
re
code -- frame rates in particular. Have you had a chance to investiga=
te
that problem?


> > 4) Hiding the non-compiled option
> >
> > I haven't looked at the KDE UI, but at the moment, the GTK menu o=
ption
> > for "Capture Video" is always shown. It would make make more sens=
e to
> > not show the menu item it when not available? Perhaps setting it =
to
> > non-active? I don't like the current message box popping up when =
not
> > available. I want to make a decision so we're consistent on it.

> Well, hiding the menu entry altogether means that people may never =
notice that
> the functionality is there. If the entry is disabled how do people =
know why
> it's disabled and how to enable it?

> I actually prefer the message box which is what I used for KDE too.=
 The text
> may need to be rewritten though.

> > 5) Some ugly code
> >
> > The code checked in is complete, but not perfect. For example, th=
ere are
> > interesting uses of the gtk mainloop code inside of a loop to ens=
ure
> > synchronization at the beginning of capture. I'll clean this up.
> >
> > 6) There is no six
> >
> > This is exciting code, so let's get it right.

> There is no 6, but there is a 0: fix that damn crash!

> --
> Christophe

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