VCD (or avi) TV playback?

[monzie]

OK, we all know DVD's and TV's have vertical (scanline) resolutions of 480/576 (NTSC/PAL)....so what happens when we play a VCD (or an avi thru an avi enabled DVD player)?

Is a VCD played back on a TV (not a pc monitor) at:>

a) Its original encoded height (240 X 352 or 288 X 352), ...but if that is the case where are the other lines of vertical..shouldnt the picture be a small central picture surrounded by black or 'noise'?

or

b) It skips an interlace field and every other pixel horizontally, to 'fill' a TV's screen yet is played as if its 'really' 60 or 50fps/2 fields (my guess)?

or

c) The hardware player interpolates the pixels back to 704 X 480 (or 576) and reintroduces (or may not) interlacing (eg 1 VCD pixel becomes a 2 X 2 TV pixel)?

d) Something else?

Also how does an avi enabled DVD player calculate an avi's playback resolution on a TV when the encoded AVI can be of variable resolutions as opposed to a VCD's 'standard' quarter size?

Anyone know? Anyone got any good explanations/links?

Its funny but when it comes to TV's (analogue) and how they work, there is VERY little info out their other than VERY BASIC information....anyone else noticed (but the digital world is full of info)?

[ZippyP.]

c) is closest. The TV scan lines never change and the player creates the video signal from the digital information spreading out the pixels over as many scan lines (vertical) and scan distance (horizontal) as required to produce the image.

TV's don't have pixels as such.

[monzie]

Thanx for the reply.

Yeh, I thought TV's dont have 'pixels' as such (as in the 'normal' pc graphix world) which I can understand....

what I cant understand is how a TV signal (anolgue broadcast), VCR, VCD or avi (through an avi enabled DVD player) aranges the vertical resolution when the vertical is less than the scanlines of the TV............

are TV's able (like pc monitors) to display resolutions below their default resolution..IE, they CAN use 240 (or 288) scanlines (or other) INSTEAD of their maximum of 480/576 (like a good 17" pc monitor can display 1600 X 1200 but is usually used at 1024 X 768 or even 800 X 600) but its display res is still 1600 X 1200 (although rarely used)?