Originally Posted by raouliii
Not really. The encoding of an anamorphic DVD has the video "pre-squeezed". The DVD player normalizes to a 4:3 letterbox or cropped output but does not normalize the video for a 16:9 output.
That is semantics though. There are 16:9 and 4:3 SD video standards - both based on 720x480 / 720x576 (in fact the digital versions are a little bit wider than 4:3 and 16:9). They both have non-square pixels. They both output video as the same length analogue active line (52us for 720x576 - a little less for 720x480 ISTR) In the two different formats the only thing that changes is the aspect ratio of the sample/pixel and the angular resolution of the format.
It is up to the display to decide which standard the video is in and display it accordingly. Yes the 4:3 standard was there first (and in the UK we had 5:4 before it with our 405 system initially) - so initially displays displayed all video in 4:3. However once 16:9 video became available (late 80s in Europe with MAC broadcasts - I watched the Barcelona and Albertville Olympics in 1992 in 16:9!) the 52us (50Hz) active line analogue video could be 4:3 or 16:9 - and TVs had to cope with both. 16:9 CRTs started appearing in Europe in the very early 90s - Thomson sold the first one I saw - just in time for the 1992 Olympics...
In Europe we have three ways of automatically signalling widescreen content in SD video. I think the US only uses one or two of them - and maybe not as universally?
1. Line 23 (maybe a different line in 60Hz SD) WSS - Widescreen Signalling - where the video content is flagged as 4:3 or 16:9 raster and also the active video content within is also flagged. (So 4:3 pillarboxed in 16:9 can be signalled, or 16:9 letterboxed in 4:3 - as well as full-screen 4:3 and full-screen 16:9) This data is carried on Line 23 (50Hz) as digital data - a bit like Closed Captioning - and I think also carries CGMS (Copy Generation Management System) flags.
2. Pin 8 SCART switching. This is a physical pin on our 21 pin EU standard SCART connector. Pin 8 can be 5V for 16:9 full-screen content and 12V for 4:3 full-screen content. This is by far the most widely supported 4:3/16:9 switching system in use in Europe. (SCART also supports RGB SD interconnects, and has since the early 80s and the days of 8bit home micros and external videotext and teletext adaptors)
3. S-video voltage offset. This uses a DC voltage offset between the luminance and chrominance signals I believe to signal 4:3 full-screen or 16:9 full-screen (very similar to SCART pin 8)
AIUI 3. is definitely an option in the US - but obviously only for S-video. 2. is unheard of in the US as SCART connectors aren't used (apart possibly from cheap imported gear) 1. would be the only option for use on component - but I don't know how widespread support for it is in the US.
However - if your display and source don't use the same widescreen signalling system - or one or both don't have any at all - then it is likely that the display will assume all SD inputs (480i/p in the US, 576i/p in Europe) are 4:3 - and require a manual over-ride to tell the display that the source is 16:9 instead.