Differences between 1080i, 720p, and 480p

[t3463]

Hello,

I am relatively new to this forum and I just bought a Toshiba 36HF71. It supports 1080i, 720p, and 480p. I believe that dvd's are currently displayed in 480p, hence the black bars on the screen, is this true. My cable company is beta testing HDTV signals and when I watch a broadcast I have a block box surrounding my picture which reduces it to about 27". Does this mean that its broadcasted in 480p? My cable company tells me that most programming is in 1080i format, does anyone know the difference between the formats? Perhaps a website that explains the differences? When my cable company rolls out HDTV I would like to be able to watch it on a full screen!!

Any Help is Appreciated

[Ratman]

First, I'll assume your set is 'widescreen' (16:9). I'll try to explain 'black bars' at the end.

Now, here's the quickie lesson...

There are progressive and interlaced pictures. With interlaced, a frame is displayed by scanning twice (IE all odd numbered lines first, then all even numbered lines). With progressive, the entire frame is is produced with one 'sweep'.

480P is 'EDTV' (Enhanced Definition TV)
720P and 1080I are HDTV.

DVD's can be displayed in either 480I or 480P depending on your DVD player. to get 480P you need to have a "progressive scan" capable player, HD ready TV, and component inputs.

Digital broadcasts (OTA, cable, satellite) can be in any format. So, even though a station is broadcasting a digital signal, it may not be in an HD format. (Check www.titantv.com for what stations broadcast 'digital' and what programs are HD). BTW... when an HD program is broadcasted: ABC is 720P, CBS 1080I, PBS 1080I, NBC 1080I, FOX 480P-Widescreen (not true HD).

With the 'cable' boxes, you need to set the box to output 1080I and connect it to you component inputs on the TV to get the proper aspect ratios.

Okay now for aspect ratios...

4:3 is displayed on a widescreen set with 'bars' on each side.
16:9 could fill the entire width of widescreen.
There are various 'flavors' of widescreen material. Some are 1.85:1, 2.35:1, anamorphic, enhanced for widescreen, letterboxed, etc....

Depending on the source materials and their aspect rations, you can/will get bars on sides or tops.

All of this can be (and is) confusing. Read what's here and between me and others that will hopefully post, we can clear up your questions/problems.