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

Buechler, Mark R Mark_R_Buechler at bausch.com
Tue Sep 14 21:20:47 EDT 2004


He's talking about non-linear scaling. I believe you're talking about
linear-only scaling which Xv is only capable of, AFAIK. 

-----Original Message-----
From: Mark Spieth [mailto:mark at dclabs.com.au] 
Sent: Tuesday, September 14, 2004 8:02 PM
To: mythtv at moasat.dyndns.org; Development of mythtv
Subject: Re: [mythtv] 4:3 content on 16:9 HDTV & Black bars - revisited

> 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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Please Note: The information contained in this message may be privileged and
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