[MPlayer-users] BPP for Frame Size

[Mark Himsley]

On 14 January 2007 11:24:13 -0400 Jorge Fábregas wrote:

> anamorphic 16:9 DVD's.  Should I calculate my video bitrate based
> on the original frame size (in my case a widescreen PAL DVD, 720x576) or
> should I consider the modified frame size at playtime (1024x576)

Hi. I'm quite new to mplayer but I work in UK TV broadcasting and I wanted 
to say how angry I get with so many people and projects continuing to say 
that PAL 720x576 should be scaled to 1024x576 to correct for 16:9 
anomorphic pixels.

Yes, I agree that 1024x576 is a 16:9 ratio. The problem is actually that 
only 702x576 of the 720x576 should be scaled up.

Because of the chosen sampling frequency (13.5Mhz) and the active line 
length (52us) actually only 702 pixels are active, the 9 at each end of the 
lines are not part of the 16:9 picture.  Have you noticed that most 720x576 
pictures have thin black bars at the edges - these are the 9 extra pixels 
at each edge.

If you are going to scale up to 1024x576 you should crop the extra 18 
pixels off or you will get pictures squished by about 2.5%

Alternatively you should scale the 720x576 pixels up to 1050x576.

The BBC has a good page on A Guide to Picture Size at.
<http://www.bbc.co.uk/commissioning/tvbranding/picturesize.shtml>

-- 
Mark Himsley
This has been a public service announcement.