[mythtv] 4:3 content on 16:9 HDTV & Black bars - revisited

Mark Spieth mark at dclabs.com.au
Tue Sep 14 21:04:56 EDT 2004


you can always then reduce the dimensions of the dest rectangle so it doesnt
go to the edge.
src rect will be zoomed to dest rect but since dest rect doesnt go to the
side it will be left at the overlay color.
this way you can have your 4:3 in a 16:9 or other frame but still have black
borders at the side. dvb here does this lots ;-). thus no fat people.
mark

> > > I've done a version of a non-linear horizontal image
> > scaling function
> > > that would stretch the edges of the video to the edge of the TV but
> > > keep the center more or less at 1-to-1.  My Hitachi HDTV
> > has this mode
> > > built-in, as do many other HDTV's I imagine.  The problem with the
> > > code right now is
> > that
> > > it is written in C and only has MMX code for Intel assembly
> > syntax and
> > > I assume it needs to be AT&T assembly.  The C code would
> > most likely
> > > not be fast enough, even on the fastest systems right now.
> > If someone
> > > would like to convert it, I could make it available.
> > Otherwise, I'll
> > > continue to
> > work
> > > on converting it to AT&T.
> >
> > you dont need to do that.
> > see the XvShmPutImage function in videoout_xv et al.. this
> > does scaling for you without loading the CPU.
> > just change the src dimensions appropriately and it happens
> > automagically by the zooming overlay mechanism in the video
> > card. (if it works correctly).
> > maximum you have to do is to reformat and crop the image
> > unless the subimage can be explicitly defined. i.e. just a
> > series of memcpy's worst case.
> >
> > mark
> >
> > >
> > > Besides that, I currently have no idea how it would get integrated
> > > into MythTV or MythVideo.  I planned to jump off that
> > bridge when I got to it.
> > >
> > > > -----Original Message-----
> > > > From: mythtv-dev-bounces at mythtv.org
> > > > [mailto:mythtv-dev-bounces at mythtv.org] On Behalf Of
> > Buechler, Mark R
> > > > Sent: Tuesday, September 14, 2004 2:54 PM
> > > > To: 'Development of mythtv'
> > > > Subject: RE: [mythtv] 4:3 content on 16:9 HDTV & Black bars -
> > > > revisited
> > > >
> > > > Sony rear projection 65". The TV is typically on from 5:00PM to
> > > > 11:00PM weekdays and during the day on weekends. I have
> > DirecTV so
> > > > all content is
> > > > 4:3 but some is 16:9 in a 4:3 format which I expand to fill the
> > > > screen. I try to do that as much as I can.
> > > >
> > > > - Mark.
> > > >
> > > > -----Original Message-----
> > > > From: Jason W. Thompson [mailto:GameboyHippo at classicnet.net]
> > > > Sent: Tuesday, September 14, 2004 2:13 PM
> > > > To: Development of mythtv
> > > > Subject: Re: [mythtv] 4:3 content on 16:9 HDTV & Black bars -
> > > > revisited
> > > >
> > > > What brand of HDTV do you have?  Do you leave myth front
> > end on for
> > > > long periods of time without turning the TV off?
> > > >
> > > > On Tuesday 14 September 2004 10:12, Buechler, Mark R wrote:
> > > > > I asked a question a few months ago about watching 4:3
> > content on
> > > > > a
> > > > > 16:9 screen with the black vertical bars. I didn't get
> > much of a
> > > > > response and I really haven't thought of it much until
> > > > recently when I
> > > > > looked at a movie which had some bright (almost white)
> > scenes and
> > > > > I noticed, very clearly, the effects of the black bars. The
> > > > 4:3 area of
> > > > > the screen looks noticeably more yellow than the black-barred
> > > > > portions. I looked at the code and it seems the black bars are
> > > > > generated from an X definition of black (possibly coming
> > > > from xcolormap?).
> > > > I'm not real familiar with X calls.
> > > > >
> > > > > I'd like to slow down the effect of the black bars by adjusting
> > > > > the black to a dark gray. Before I look further into it, has
> > > > > anyone already
> > > > done so?
> > > > > Is there a patch already out there? I'm quite concerned
> > > > after seeing
> > > > > the effects on a TV which is only a year old and doesn't
> > > > get much use
> > > > > during the day.
> > > > >
> > > > > Thanks, Mark.
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > Bausch & Lomb
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>
> Wouldn't that result in just a linearly scaled image?  I don't have the
> source handy at the moment but I have yet to find an image scale function
> that can stretch the images more towards the edges while leaving the
center
> of the image intact.  All I've ever found is just a linear scale that
makes
> everyone look fat in the image.
>
>


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