[MPlayer-users] Re: Changing aspect ratio while playing a file

[Rich Felker]

On Wed, Nov 16, 2005 at 09:12:46PM +0100, Sebastian Kaps wrote:
> Hi Tony!
> 
> > I think Sebastian (the OP) may have misuderstood exactly what
> > -monitoraspect does. It doesn't scale the video to *fill* the given
> > aspect, it scales it to fill as much of a screen of that shape as
> > possible while preserving the original aspect ratio.
> 
> Yes, that is how I understand this option.
> 
> > So whatever video you play with -monitoraspect=16:9 it will display
> > correctly on a 16:9 screen. 4:3 videos will have black borders at the
> > sides and 2.35:1 videos will have black borders at the top.
> 
> That is correct, but think about it for a second. In order to make a 4:3
> video look correct on a 16:9 screen in 16:9 mode, you have to scale it
> horizontally by a factor of roughly 0.7. If you wouldn't downscale the
> video, it would fill the whole screen.
> But when you do, you lose 30% of the horizontal resolution, because the
> video is no longer 720 pixels wide (PAL), but 504 pixels. The 16:9 mode
> of the TV then stretches these 504 pixels to fit into 720 pixels on the
> actual screen.

The actual TV does not have pixels. Pixels are a digital artifact.

> That's nuts, since all 16:9 TVs I know do have a 4:3 mode where 4:3
> videos are displayed in a 4:3 area on the center of the screen (i.e.
> black bars left and right). So you won't lose anything if you leave 4:3
> videos unscaled and switch the TV into 4:3 mode.

The amount you lose is the same either way if you have good
(component) cables, maybe even with SVIDEO. If you have composite then
yes it will suck.

Rich