1080i and 1080P difference?

sebastianj

Hi,
Some of the play back storage devices quote HD1080i and some HD1080P, why is that? Can someone shed some light on this please.
seb

shandypants5

sebastianj wrote: »

Hi,
Some of the play back storage devices quote HD1080i and some HD1080P, why is that? Can someone shed some light on this please.
seb

1080i is "interlaced. this means the picture scans all the odd numbered lines first, then all the even numbers.

1080p is "progressive" that means all the lines scan one after the other.

They are both good for different jobs.

Interlaced can give problems with fast moving sports and can show annoying "ball smear"

But "interlaced" is better for movies as the way they are coded for tv is different, so you get a more cinematic picture.

sebastianj

Many thaks Shandypants,5 for a conclusive answer.
So if I am into support then go for 1080P otherwise 1080i will suffice, thanks again.
seb

aliEnRIK

Interlaced actually shows the odd numbered lines then the even number of the NEXT frame (Not the same one)
Tvs with bad deinterlacers (showing an interlaced picture) can look awful

"But "interlaced" is better for movies as the way they are coded for tv is different, so you get a more cinematic picture." ~ im sorry but thats absolute rubbish!

shandypants5

aliEnRIK wrote: »

Interlaced actually shows the odd numbered lines then the even number of the NEXT frame (Not the same one)
Tvs with bad deinterlacers (showing an interlaced picture) can look awful

"But "interlaced" is better for movies as the way they are coded for tv is different, so you get a more cinematic picture." ~ im sorry but thats absolute rubbish!

Not really rubbish Rik Movies and sport are recorded in different ways.

As far as I am aware (and I may be wrong please feel free to correct me.)

Movies are origionally made on film that has a refresh rate of 25 frames per second
So when they are converted for TV they dont show a new frame every time the tv scans.
In fact the same frame may be shown while the tv scans the screen twice or even three times.

For this reason the "smoother" scanning of interlaced gives less flicker than progressive.

Sport on the other hand is usually recorded on a modern digital camera and is nearly always recorded in 1080i.
This means that if you play the picture on an interlaced TV the ball is shown in one place, but then when the odd lines are scanned the ball has moved slightly, so you get the impression of the ball smearing across the screen.

aliEnRIK

Unless you really need me to explain. That is completely wrong in just about every way

shandypants5

I know you know your tellys Rik so.
If it wont take up 20 pages I would like you to explain please, I thought I understood.

Or link please can you me to a page so I can re,evaluate my understanding.

aliEnRIK

Im off out now so ill be brief (Id post a link if I could but I dont know of any single link that explains it really)

Interlaced is as ive already said, showing one half of the image on frame 1 then the OTHER half of frame 2 (not the same frame). Thats why progressive 'bandwidth' is so much more as its showing the entire picture frame by frame
To show interlaced pictures, either the tv or the source need to 'deinterlace' them (Form a picture from 2 entirely different frames)
Movies are generally recorded in 24 fps, which is why blurays are 24Hz to match (ANY conversion process is bad, interlaced HAS to be converted)
All other material can be recorded in a number of ways, but its generally very poorly converted to work on tvs as the frames dont match the framerates (Another conversion process)
Sport cant be recorded well using ANY medium yet as the framerates are just not there (24hz is very poor and seriously needs upgrading, but as everything else is converted anyways its the best picture we can currently obtain)

Anyways, im drifting onto a few different areas of film there. The basic is progressive doesnt need any conversion process (Save whatever conversion process it went through before it was recorded to disc or whatever). Interlaced MUST be deinterlaced, and more often than not needs to have the frames worked out in such a way as to work with 50Hz tvs. aka, interlacing will never be as good as full frame progressive (n a nutshell)

On the flip side, a very good deinterlaced film would be hard to distinguish from a full progressive one

Avoriaz

shandypants5 wrote: »

…Movies are origionally made on film that has a refresh rate of 25 frames per second
So when they are converted for TV they dont show a new frame every time the tv scans.
In fact the same frame may be shown while the tv scans the screen twice or even three times..

I’m not fully up to date on modern broadcasting practice but it was certainly true some time ago that films shot at 24 frames per second were shown on British TV at 25 frames per second in order to easily match the 50 half frames per second TV image.

A film that ran for 90 minutes in the cinema would run for just over 86 minutes on TV. This 4% increase in speed was not really noticeable to the viewer and was a far better solution that trying to convert 24 fps into 25 fps.

I would be surprised if this practice has changed but I don’t know for certain as I haven’t kept up to date.

donnajunkie

aliEnRIK wrote: »

Interlaced actually shows the odd numbered lines then the even number of the NEXT frame (Not the same one)
Tvs with bad deinterlacers (showing an interlaced picture) can look awful

"But "interlaced" is better for movies as the way they are coded for tv is different, so you get a more cinematic picture." ~ im sorry but thats absolute rubbish!

i agree. i think they are getting slightly confused with what they say. i believe the accurate thing to say would have been 720p is good for sports but 1080i would be better if you watch a film. however 1080p is still better than both providing the 1080p scaler can do its job well enough.

aliEnRIK

donnajunkie wrote: »

i agree. i think they are getting slightly confused with what they say. i believe the accurate thing to say would have been 720p is good for sports but 1080i would be better if you watch a film. however 1080p is still better than both providing the 1080p scaler can do its job well enough.

Whats a scaler got to do with differences between interlaced and progressive?