[opendtv] Re: Finally anamorphically compressed 480i

  • From: Albert Manfredi <albert.e.manfredi@xxxxxxxxxx>
  • To: <opendtv@xxxxxxxxxxxxx>
  • Date: Sun, 23 Jan 2011 01:33:02 -0500

John Shutt wrote:
 
> But then we would be lowering the effective horizontal resolution of
> the 4:3 material, which still makes up the vast majority of
> programming on an SD channel.
 
Oops, I really blew this last time.
 
Right. If you send 4:3 SD typically as 640 X 480, all that 640 would be 
horizontal image resolution, either on a 4:3 set or a 16:9 set. If instead you 
send it as squeezed and pillarboxed 704 X 480, the effective horizontal pixels 
would be 529 (= 704 * 1.33/1.77). So like you say, you do lose horizontal 
resolution.
 
For the old analog 4:3 sets, that's still probably more horizontal resolution 
than they need.
 
> Almost 100% of the AFD encoded material we receive from PBS is HD
> material, with AFD instructions for downconversion.
 
Most of PBS SD content seems to be pillarboxed 4:3, although I've occasionally 
seen postage stamp 16:9 too. So I take it the stations don't have much say in 
how that gets sent out over SD subchannels.
 
Bert
                                           
 
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