Celestia Forums

Hi,
at first I must say, that I?m very impressed by this program.
But I?m living in europe and want to know, if it is possible to create a new video capture frame with 720x576 pixels. This is the standard for the european PAL-videosystem.
Hope, someone can help me.
Grettings from Berlin!

Im sure chris could implement the codec for PAL video transfers but the best bet right now is using something like FlaskMPEG or Adobe Premier to convert to PAL format...The standard of DivX will play out to any television from a computer without enhancement though...depending on your equipment...Ive played PAL format on my computer out to my TV without a hitch...

Hi Rassilon,
thanks for your answer. But it is not the problem to playback in PAL, the problem is the wrong format. If I load the avi-clip in premiere, it is transformed to 720x576 and the earth looks like an oval and not as round as it should be (Height of 480 transformed to 576). That?s my problem.
It would be fine, if someone has already solved this problem.

More greetings from Berlin.

For version 1.2.6, I'll add 720x576 to the list of resolutions. It's a very simple fix.

--Chris

Hi Chris,

that?s what I meant. I?m hoping V.1.2.6 will come soon.
Thank you for your efforts.

Greetings from Berlin

chris wrote:For version 1.2.6, I'll add 720x576 to the list of resolutions. It's a very simple fix.

--Chris

Just for info
The european PAL video standard 720x576 has a non-square pixelaspect-ratio of 1.067.
(720x540 or 768x576 is the PAL equivalent with square pixelaspect-ratio 1.0)

Since celestia renders only with square pixelaspect-ratio 1.0 for now, it's always necessary to rescale a captured video (avi) from celestia into non-square pixelaspect-ratio in order to make a planet on PAL TV output round.

In other words, a round planet on the computerscreen is always an egg on an PAL-TV and via versa, because a pixel on computerscreen is always a square and a pixel on TV is always a rectangle.

So you sould implement two capture PAL video formats:
720x540 and 768x576 - which have both to be rescaled to 720x576 in an external program like AfterEffects for correct TV output.

I prefer 768x576 because x and y are multiples of 16 so the AVI-Compressors run much faster.

BTW: NTSC Video Standard is 720x486 with pixelaspect-ratio 0.9.

Ingo

Ingo,

I'm sorry to say that your description is both confused and confusing.
The number of samples per scanline is arbitrary. What matters to the video hardware is the timing of the vertical and horizontal sync signals.

The scanrates supported by modern computer graphics hardware, both the cards and the monitors, are much less restrictive than they used to be, but most computer graphics packages, including Celestia, haven't kept up.

In order to produce the correct aspect ratio for a video recording device, the user needs to be able to specify the number of pixels per scanline, the number of scanlines, the horizontal refresh rate and the vertical refresh rate. (I'm ignoring some of the other timings that can be controlled, like what's called "frontporch" -- the time between the horizontal sync signal and when the first visible video signal is generated.) Specifying only the number of visible pixels per scanline and the number of visible scanlines really isn't enough.

Simplifying things for the less expensive video cards, is another matter.

Sorry: I got interrupted and then distracted by some other posts..

At any rate, I suggest that Chris also include the option of specifying 25/30/50/60 Hz refresh rates when setting the appropriate square pixel aspect ratios -- or add to the menu item the scanrate that's set for a given pixel resolution. This would reduce the visual artifacts introduced by cards with TV outputs (since the scanrate would be an appropriate multiple) as well as simplify the conversions needed for the various movie editing packages.

For example, some obvious video resolutions might be
640x480x60Hz (vga, 2xntsc)
720x480x30Hz (ntsc, non-square pixels)
1280x720x60Hz (hdtv)
1920x1080x30Hz (hdtv)
1920x540x60Hz (hdtv/2)
720x576x25Hz (pal)

and others...

Selden,

you are right if your are talking about TV output for computer graphic cards, but trust me, if you are using professional D1 video equipment with component YUV or digital SDI video output, you have to take care about this pixel aspect ratio stuff.

Programms like Adobe AfterEffects or 3D Studio Max have rendering presets for D1- NTSC and PAL video standards to render nonsquare pixels.

Ok, I'm working at an animation company and will never use a computergraphic card for video output. My posting was just for info and to make Celestia a bit more convenience for professional video recording.

As I mentioned before, I prefer 768x576 for PAL, because x and y are multiples of 16 so the AVI-Encoders run faster.

Ingo

Ingo,

Thanks for the clarification.
My experience has all been with analog signals and, to a certain extent, using graphic card output for HDTV front projection.