[mythtv-users] HD Resolutions

[Andre]

On 5 May 2011, at 10:52, Jacob Mansfield wrote:

> simple question, which is better: 1080i or 720p

Is there ever a simple question? ;-)

720p (at 50 or 60 frames a second) is better for sports due to the higher frame rate.

1080p (at 24, 25 or 30 frames a second) is better for movies and drama shot at those low frame rates.

It's not easy (currently possible) for a studio and broadcast playout center to change formats from show to show so 1080i is commonly chosen as a compromise between the two.
1080i when used to deliver a 1080p movie can be re-assembled (de-interlaced) in the TV as an exact copy of the 1080p original, there are some differences in compression efficiency but mostly it's fine.

1080i when used to deliver a sports (or other high frame rate show) gives better motion than 1080p(25 or 30) but has several problems to accurately portray fast motion (motion blurring is worse horizontally than vertically, objects only come into sharp focus when they move slowly or stop, etc. etc. etc.) 1080i has a similar "look" to standard definition TV so it's flaws are accepted by viewers who are used to it's oddities. De-interlacing a fast moving sports picture without making every thing look soft is a difficult process.

Often the biggest difference in flat panel TV "quality" is how well fast motion de-interlacing works, it's also the reason behind all the vdpau advanced 2x de-interlacer discussions on here. It's often why Plasma TVs look better for sports than LCD due to less interaction between display refresh "issues" and de-interlacing "issues"!

In tests many viewers find fast camera pans used in sports TV nausea inducing when 720p50 or 60 is used. Provided there is consideration and understanding of the issues  sports at 50 or 60 frames is vastly better, especially noticeable on poorer flat screen TVs. 

Very few broadcasters transmit true 720p, Fox in the USA is true 720p, ORF & HD Suisse in Europe but they are mostly transmitting programmes made in 1080i and converted at transmission to 720p.

The EBU rule of thumb for resolution is usually up to 40" display there is very little perceptible difference between 720 and 1080 above 50" 1080 becomes a significant advantage.

There are usually many other effects involved between 720p and 1080i unless you are watching on grade 1 crt monitors in the studio so it's very difficult to compare the two at home after transmission.

For slow movement (or things made using film techniques) 1080i is sharper, for sports and regular TV (using normal TV techniques) 720p(50 or 60) is sharper.


Now there will be people pointing out the many over simplifications I have made and many people arguing that one looks better than the other on their TV ;-) all of which is true.

Andre


> Jacob Mansfield
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