[MPlayer-users] Re: Crop before deinterlacing OK?

[Rich Felker]

On Mon, Jul 25, 2005 at 11:56:06AM +0200, Matthias Wieser wrote:
> Am Montag, 25. Juli 2005 00:48 schrieb Rich Felker:
> > On Sun, Jul 24, 2005 at 07:31:13PM +0200, Matthias Wieser wrote:
> > > Am Sonntag, 24. Juli 2005 04:40 schrieb RC:
> > > > On Sat, 23 Jul 2005 18:12:54 +0200
> > > >
> > > > Matthias Wieser <mwieser at gmx.de> wrote:
> > > > > Maybe I am the only one who does not like pp=lb
> > > > > because of this effect:
> > > >
> > > > No, you're definately in the majority.  I seem to be almost the
> > > > only person around here using pp=lb.
> > >
> > > Have you ever tried pp=l5? It seems to be a variant of pp=lb which
> > > produces slightly more sharpness. I think it should not have any
> > > disadvantages.
> >
> > It has all the same disadvantages as lb, plus the disadvantages of a
> > sharpener (hurting compressibility and not improving quality).
> 
> Maybe not improving psnr but I think it improves visual quality. I have 
> done some tests with different test patterns and the deinterlaced result 
> of pp=l5 is much more comparable to the original as the one from pp=lb.
> 
> (btw.: when measuring the psnr between the original and the scaled down 
> and encoded video, sws=2 or sws=6 often results in higher PSNR than sws=1 
> or sws=7)
> 
> > It's 
> > exactly the same thing as running pp=lb followed by a simple -1,4,-1
> > sharpening filter.
> 
> But as pp=lb by the very nature of the system introduces some vertical 
> blurring this sharpening might improve the overall quality.

If you weren't going to encode, yes. But a sharpening filter will just
hurt compressibility and lower the psnr of the actual encode.

> > > > The ghosting looks dramatic in still images, but it doesn't bother
> > > > me much at 30fps (except VERY fast scrolling text, which is rare).
> > >
> > > With TFTs it is getting even worse because pp=lb lowers the contrast
> > > at the edges of moving objects which rises the response time of TFTs.
> >
> > I don't think this has anything to do with it..
> 
> The response time of most TFTs is dependent on the contrast between the 
> two colours. Sharp edges as they are produced by pp=fd result in higher 
> local contrast between the actual and the last frame which in result is 
> good for TFTs.
> For example: a black object is moving over white ground.
> when using pp=fd the response time from black to white and from white to 
> black is relevant. 
> When using pp=lb the respons timee from black to gray, gray to white, 
> white to gray and gray to black are relevant which often need much more 
> time than switches between black and white.

Again I really do not think this is the issue at hand. I know what
you're talking about but it's hardly relevant. The ghosting you see is
just because pp=lb created a nasty ghost. It's visible on CRT too.

Rich