[mythtv-users] 5200 or 6200

Steve Hodge stevehodge at gmail.com
Thu Jan 25 01:03:11 UTC 2007

On 1/25/07, Nick Morrott <knowledgejunkie at gmail.com> wrote:
> 1080p60 has twice as many pixels/s as 1080i60, as Jarod stated earlier:
> 1080i60 = (1920x540 pixels per field) x (60 interlaced fields per
> second) = 62,208,000 pixels/second.
> 1080p60 = (1920x1080 pixels per frame) x (60 progressive frames per
> second) = 124,416,000 pixels/second.
> 1080p30 will have the same datarate as 1080i60 however, and fast
> action scenes may look smoother using the 1080i60 format.

Right. For fairly static scenes the field rate is less important and 1080i
will approach 1080p in quality. For rapid movement field rate makes more
difference and so 1080i will not look as good as 1080p at the same field
rate, but will look better than 1080p at the same data rate (i.e. 1080p60 is
better than 1080i60 is better than 1080p30). Really interlace should be
considered to be a lossy compression scheme.

But keep in mind the source material. Movies are (generally) shot at 24 fps,
so Xp60 contains alternately duplicated and triplicated frames, i.e. 60% of
the data rate is completely wasted. Xi60 has more than enough bandwidth to
transmit all of the source pixels without any loss. If accurate inverse
telecine is possible the 1080i60 signal will result in exactly the same
output as 1080p60. I think this is what Steve Adeff was trying to say. Of
course this doesn't apply if the source is Xp60 material.

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