Short Version: Add Display Aspect Ratio options for 15:11 and 20:11. Also (less importantly) 1.37, 1.66, 1.85, 2.35, 2.39.

The aspect ratios for Standard Definition content on DVDs is all wrong. The only options are Square, 4:3 (Generic), 16:9 (generic) and 2.21:1 (DVB). There are no options for custom aspect ratios as in the advanced options of VLC.

DVDs and Bu-Rays with standard definition content use 720 horizontal pixels.

A video at 720x480 (DVD or Blu-Ray or DVB) has the same Pixel Aspect Ratio as 704x480 (which is 10:11 or 40:33).

What this means is that while video files at 704x480 resolutions use a Pixel Aspect Ratio of 10:11 stretch out to a nice 4:3. Likewise for 40:33 PAR resulting in a Display aspect ratio of 16:9.

These are the cropped digital video files.

When the ITU laid out digital video in CCIR-601 it was decided that 704 horizontal samples would represent 4:3 or 16:9. However, equipment captured 720 samples because the signals weren't always centered. There was the option to focus on the active 704 pixels and crop. The other option, if the image were centered, was to play as is. (This is what D1, DVDs, and Blu-Ray standard def content all do).

The resulting image, when played back, with those extra 16 pixels at the sides resulted in a picture that was 15:11 or 20:11 (720*10/11 > 640; 720*40/33 > 852)

Adobe Premiere (CS4+), Sony Vegas, Final Cut, etc ALL use this pixel aspect ratio.

That means a video with 720 horizontal pixels has a Display Aspect Ratio that is slightly WIDER than 4:3 or 16:9. Analog TVs ignore the edges of the signal because the signal would start too early and end too late. A digital TV would either crop them or just show the total image slightly wider so that the true image stays the right ratio.

Totem only allows exact 4:3 or 16:9. The flags on DVDs are relative (square or rectangular) they don't specify the exact details. The MPEG fools used DAR instead of PAR. If they just used PAR we'd all be fine, but they didn't.

The only violators of this principle are most of the Hollywood DVDs. They use all 720 horizontal pixels and do a straight re-scale with a Pixel aspect ratio of 8:9 or 32:27. However, films are being moved to Blu-Rays, so this is irrelevant. Some studios DID follow the guidelines, see the Bond films or the Criterion Collection discs. All digital and analog-digital converted video (not film) uses 704x480 pixels at the standard PAR and adds those 8 black pixels to each side.

Standard Definition content will never be up-scaled to 1920x1080. It will only be offered at 720x480. This problem won't go away.

Why must my BBC DVDs forever be in the wrong aspect ratio? Why must DVD-ready files that I edit be displayed this way? Ripping/Trans-coding is also a pain in the butt with many discs and I'd rather just pop and play.

For many years Adobe (with no video background, unlike Sony, for example) got this wrong and when they corrected it, there was a lot of confusion.

http://help.adobe.com/en_US/encore/cs/using/WSbaf9cd7d26a2eabfe807401038582db29-7fb2a.html#WSbaf9cd7d26a2eabfe807401038582db29-7fb1a
http://forums.adobe.com/thread/700836
http://help.adobe.com/en_US/PremierePro/4.0/WS03BF7479-8C7B-4522-8C75-210AD102524Ea.html

Also, there are public domain videos that are old, have little interest in them, and have been poorly encoded and then uploaded as video files.

The Aspect Ratios are all a mess. Either the flag is missing or the conversion to square pixels was done poorly. How about options for Academy Ratio 1.37:1, 16mm at 1.66:1, 3/4 perforated 35mm at 1.85:1, and Cinemascope (old) 2.35:1 and Cinemascope (new) at 2.39:1?

Everything applies equally to 704x576 and 720x576 which use the PAR of 12:11 and 16:11.