Have notice recently a new format starting to appear for some programs on TheBox.

Example, today they have Top Gear episode available in these formats:-

PDTV Xvid 509.14 MB

HDTV 72p (x264) 1.61 GB

HDTV 1080i (x264) 2.25 GB

The first two, I guess, are normal and High Definition but what about the HDTV 1080i (x264) at a whopping 2.25 GB

What's that all about ?

The 72p is actually 720p. That's HD 720 lines progressive display. It's a sort of halfway house between regular SD and full HD.

"Proper" full HD as you would get on BluRay is 1080p, that's 1080 lines progressive display.

Broadcast HD is often 1080i, that's 1080 lines of interlaced display. If a broadcast HD stream is recorded off-air then this is what you will get.

These standards have been around for many years.

Good explations on you-tube about HD resolution.

1. 1080p = HD

2. 720p = HD

3. 1080i (actually only 540p) low-res HD

720P is true HD, not halfway between SD and HD.

Broadcasters are using either 720p or 1080i. 720p is better.

1080p is only available from the internet or Blu-Ray.

1080p is standard at many german commercial tv stations...

So nothing for me to get exited about till I win the lottery and buy a HD television

Thank you

3. 1080i (actually only 540p) low-res HD

Not correct, the same amount of information is displayed in either 1080i (interlaced) or 1080p (progressive). The difference is how they put up the information. 1080i interlaces one scan field of 540 lines then the 2nd field of 540 lines still giving you 1080 data and no loss in resolution. 1080p on the other hand displays in one scan the full amount of information.

1080i versus 1080p

More detail here:

1080i, the former king of the HDTV hill, actually boasts an identical 1,920x1,080 resolution but conveys the images in an interlaced format (the i in 1080i). In a tube-based television, otherwise known as a CRT, 1080i sources get "painted" on the screen sequentially: the odd-numbered lines of resolution appear on your screen first, followed by the even-numbered lines--all within 1/30 of a second. Progressive-scan formats such as 480p, 720p, and 1080p convey all of the lines of resolution sequentially in a single pass, which makes for a smoother, cleaner image, especially with sports and other motion-intensive content. As opposed to tubes, microdisplays (DLP, LCoS, and LCD rear-projection) and other fixed-pixel TVs, including plasma and LCD flat-panel, are inherently progressive in nature, so when the incoming source is interlaced, as 1080i is, they convert it to progressive scan for display.

CNET

As opposed to tubes, microdisplays (DLP, LCoS, and LCD rear-projection) and other fixed-pixel TVs, including plasma and LCD flat-panel, are inherently progressive in nature, so when the incoming source is interlaced, as 1080i is, they convert it to progressive scan for display.

CNET

This is new information for me. Never seen before when I was getting up to speed on HD.

So why is it the poor cousin to 1080p?

So why is it the poor cousin to 1080p?

An interlaced system needs two scans to produce a complete frame, a progressive system has a complete frame per scan (and therefore requires a much higher data rate / bandwidth). This means that all other things being equal an interlaced system has half the frame rate of a progressive system.

It's all historical, when the HD standards were developed everyone was still using CRTs which flicker less when interlaced. LCDs etc are inherently progressive in nature, if they had been widely available when HD was first proposed interlaced HD would probably never have happened.

1080i and 1080p have exactly the same resolution and under normal (non-sports) viewing are pretty well indistinguishable. Add fast movement into the mix (sports) and 1080p (and in reality 720p) wins hands down.

In fact televisions always used to be interlaced.

Only half the picture sent a time, first frame odd lines, then the next even, and so on.

It all happening at 50 frames per second (60 in the US) so the eye perceived the whole

picture, but really it was a trick to reduce the amount of data sent in each frame

Around 1990 there were some "100Hz" TVs on the market, mainly large screen

that used memory to retain each half of the picture and display it all at once

which did give a better image.

For the HD channels I can see here in the Middle East, they are either 1080i

or 720p