[mythtv-users] BBC HD (1080) h.264 / AVC playback

[Nick Craig-Wood]

Tim Small <tim at buttersideup.com> wrote:
>  Yeechang Lee wrote:
> > Tim Small <tim at buttersideup.com> says:
> >   
> >> I used mplayer to play back recordings of "Planet Earth" in 1080p - 
> >> 1440x1080 16:9 25(?)fps - files which mythtv has recorded (but not 
> >> transcoded).
> >>     
> >
> > It's unclear whether you are saying you are playing back the
> > transmission on a 1080p display, because 1440x1080 of course is not
> > true 1080p (or 1080i).
> >   
>  OK, are you sure that this is the case?  1080 lines with square pixels 
>  at 16:9 does of course imply 1920*1080, and there certainly is content 
>  available encoded at this res, but as I understand it, the brain is more 
>  sensitive to vertical detail than horizontal, hence the BBC's choice of 
>  1440x1080 with rectangular pixels...  Is there actually a definition of 
>  "true 1080p" anywhere?  I couldn't find one...

I think the more important difference between 1080i and 1080p is that
1080i has a new frame every 25/30 Hz (displayed interlaced at 50/60
Hz) whereas 1080p as a new frame ever 50/60 Hz.  1080p is twice the
bandwidth of 1080i.  Both 1080i and 720p have the same bandwidth - and
that bandwidth is about the maximum bandwidth you can fit down all the
old cabling in all the tv studios around the world.  1080p requires
new cabling and isn't common yet.

What you've noticed is that your 1080i frames aren't interlaced.  This
is common (at least in the UK) for stuff which came from a
non-interlaced source like film.  You can show this kind of video at
25 Hz and not bother about de-interlacing.

-- 
Nick Craig-Wood <nick at craig-wood.com> -- http://www.craig-wood.com/nick