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

[Tony Houghton]

In <m3lkzoz2w7.fsf at toyland.sauerland.de>, Sebastian Kaps wrote:

> Hi Tony!
> 
> >> 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.
> 
> > That's as long as the TV has enough phosphor to still show all the
> > detail,
> 
> Well, I assume that's always the case. The 4:3 area of a 16:9 screen
> should always have at least 720x576 physical pixels. Otherwise nobody
> would buy a 16:9 TV.

I'm not so sure. I wouldn't be surprised if at least some TVs,
especially cheaper ones, don't have fine enough phosphor to resolve 720
pixels across 3/4 of their width.

> > but I think you're right to want to do it that way anyway: if you can
> > tell any difference, the "natural" scaling of the TV should in theory
> > look better than software scaling.
> 
> By "natural scaling" you mean showing a video with a resolution larger
> than the physical resolution of the output device? Like what happens
> when you switch a 15" CRT monitor to 1280x1024?
> In my opinion this should not occur in my case.

That's not quite what I mean. Maybe I should have called it "mapping"
rather than "scaling". Even if you consider each set of 3 phosphor dots
to be a pixel, I don't think they're arranged in a rectangular grid, so
it's impossible for pixels to line up with them. The (triple) scanning
beam just lights them up as it passes over, and its intensity varies
with the input, which is an analogue conversion of the pixels, so the
frequency limits of the convertor and the signal path smooth out the
pixel borders anyway.

> > I've snipped some relevant bits out of a script, so this may not work
> > correctly. 
> 
> Thank's, I'll have a look at the script tomorrow.
> A native mplayer function would be desireable, though.
> Any developers reading this?
> It shouldn't be much of a problem to implement this feature since the
> basic stuff has to be there already for the "monitoraspect" option.

Yes, something like "-monitoraspect auto" would be nice. Even better if
it supported WSS on the TV out. The DXR3 is the only TV-out device I've
heard of with that feature, but I don't know whether MPlayer supports
it. What graphics card do you use for your TV out BTW? I use a Matrox
G450.

-- 
TH * http://www.realh.co.uk