[mythtv-users] dumb hdtv questions

[Brad Templeton]

On Wed, Mar 23, 2005 at 02:24:17PM -0500, Cory Papenfuss wrote:
> >It's the high resolution.  Also 1080i is harder to play than 720p not
> >just because the high resolution but also because most people like to
> >deinterlace it on progressive displays.
> >
> 	Just from a raw pixel rate you've got this:
> 
> Signal	Resolution	Pixels			Relative pixelrate
> NTSC:	720x480 at 30Hz	= 0.345Mpixel at 30Hz	= 1:1 (480i)

Actually, as I understand it, broadcast NTSC can be more accurately
presented at around 352x480, perhaps 480x480 at most.   SDTV (which
would describe what you get from an interlaced DVD or a digital SDTV
broadcast) is as much as 720x480i.   

> 480p:	720x480 at 60Hz	= 0.345Mpixel at 60Hz	= 2:1
Known as EDTV though in theory that's any progressive frame rate.  This one
confuses me a bit.   Films are shot at 24fps, so therefore doing them at
60fps interlaced (30 full frames/second) contains as much information as
doing them at 30fps or 24fps progressive.  With the right decoders should
be able to lok th same.

> 540p:	960x540 at 60Hz	= 0.518Mpixel at 60Hz	= 3:1
> 720p:	1280x720 at 60Hz	= 0.912Mpixel at 60Hz	= 5.3:1
> 1080i:	1920 at 1080@30Hz	= 2.074Mpixel at 30Hz	= 6:1
> 1080p:	1920 at 1080@60Hz	= 2.074Mpixel at 60Hz	= 12:1
> 
> 	Figure it takes a 450MHz machine to play SDTV DVD.  Multiply by 6 
> to get 1080i HDTV and you get 2.8GHz machine.  Grossly inaccurate due to a 
> multitude of reasons, and oversimplified, but it gives you a ballpark 
> figure of how many more pixels need to be calculated compared to SDTV 
> (480i).

Also note 1080i deinterlaced with bob results in 60fps.