[mythtv-users] OT: Why 1080p?

[Michael T. Dean]

On 11/07/2006 07:19 PM, Steve Hodge wrote:
> On 11/8/06, Ed O'Brien <ed3120 at yahoo.com> wrote:
>   
>> - 720p is superior to 1080i.  (I don't understand this at all.  I've watched
>> a lot of 1080i and 720p and I like 1080i much better.)
>>     
>
> You're getting more information with 1080i:
> 1280*720*60 = 55.3 megapixels per second,
> 1920*1080*30 = 62 megapixels per second.
>
> BUT. Research has shown that the human visual system is more sensitive
> to vertical resolution than horizontal resolution. This is why HD (and
> even SD) resolutions are generally known by the number of lines the
> contain. So, ignoring horizontal resolution:
> 720*60 = 43,200 lines per second, and
> 1080*30 = 32,400 lines per second.
>
> By this measure 720p is better, even ignoring interface artifacts.
>
>   
>> The thing that I don't understand is that every anti 1080i argument I hear
>> uses flickering as a downside, but I don't understand why they think it
>> matters.  Every quality display today (Plasma, LCD, DLP, LCOS) is
>> progressive scan and therefore deinterlaces all content before displaying
>> it.
>>     
>
> Deinterlace is difficult to do well. Some people prefer 720p to
> de-interlaced 1080i (which has a vertical resolution somewhere between
> 540 and 1080).
>
>   
>> I understand that 1080p might be better for video games, but other than
>> that...I just don't see why it would be considered better than 1080i scaled
>> to 1080p.
>>     
>
> Do you mean 720p here? Clearly 1080p60 is superior to 1080i60, I don't
> see how you could believe otherwise. No matter how good your
> deinterlace is, it's not going to be as good as having the extra
> information in the first place.

The assumption that there is additional information is a big assumption 
considering you haven't specified the source of the video.  Until you 
know the source format /and/ the transmission format, you can not say 
that 1080p60 has more information than 1080i60.

If, for example, the source were 1920x1080 at 24 frames/sec and the 
transmission formats you can choose are 1080i60, 1080p30, or 1080p24, 
they all have exactly the same information in them*.  It's just that 
some of the formats have more /redundant/ information in them (= wasted 
bandwidth).

*True, I am assuming an ability to filter the video with a proper ivtc, 
but the point is there is /no/ additional useful information in the 
signal at 1080p60 in this circumstance.

Mike