Re: FN-FORUM: FW: Flash to DVD continued

date posted 26th June 2007 14:46

chris hill wrote:

> widescreen is where things get complicated and I dont know too much
> about the differences. I'm fairly certain, with the exception of new
> HDTV's, All CRT tv's, widescreen or not, are fixed at 720x576 (unsure
> on non HD plasma/lcd but I guess they are the same). Think of the
> resolution as being hard-wired into the tv (since it sort of is!)
> since the screen in made up of a number of pixels which are actually
> like tiny little lights.

Widescreen video on DVD is either anamorphic or letterboxed.

Letterboxing is taking a source video with a resolution of, say, 720x400
(aspect ratio of 1.8:1) and adding black bars at the top and bottom to
create a frame of 720x576. The bars are then encoded as part of the
video stream.

Anamorphic widescreen involves squeezing a video with an aspect ratio
greater than 4:3 into a 4:3 frame. If you played it back as 4:3 video,
it would look compressed horizontally, but there is a flag in the MPEG
stream that tells the decoder in which aspect ratio to display it. It's
then the decoder's job to add the black bars. Anamorphic widescreen is
the most popular method these days.

Also, Video CD and Super Video CD use lower resolutions than DVD, so
bear that in mind if you plan to use them. There is another format
called Mini DVD that puts a whole DVD filesystem on a CD (useful for
short videos), but not all players support this.

Neil