This is an old issue, but one that still comes up often enough for me.
I haven’t authored a 4:3 DVD in years. This is because I haven’t seen a 4:3 screen in years. Almost every television and computer monitor is now being made with a 16:9 (widescreen) aspect ratio.
However, we still delve into the archives often enough to find SD video that was shot 4:3.
When creating a widescreen DVD in Adobe Encore, these 4:3 videos usually wind up getting “stretched” on the screen to force 4:3 to conform to the 16:9 aspect ratio. This is especially problematic when the video stretching makes your wife’s butt look wider than it actually is (doh!). Thus, finding a solution was imperative.
For a specific example: I recently created a "wide screen" DVD of 20 or so archival live dance videos, along with some newer live dance videos as well as some dance for the camera pieces we had recently created. Some of the archival videos were from quite a few years ago and had been shot 4:3, though most were shot 16:9. When viewing the DVD (which is created as 16:9), there were still a few videos displaying 4:3 stretched to 16:9 rather than "pillar boxed" so there was no stretching.
Most of the clips were also rendered out of Premiere with the correct MPEG-DVD settings so that no transcoding was needed. However, a few videos were still being transcoded by Encore, and this is where the problem was arising.
The solution for me was to go to those videos, right click on the video asset (not the timeline, but the actual video), "revert to original," and then "select transcode settings." From here I could set the transcode setting as 16x9 HQ DVD instead of "automatic" so that the final video output was widescreen instead of the 4:3 that was getting stretched (Encore wants to leave a 4:3 original video as 4:3, which might make sense, but is not what we want for a 16:9 DVD!).
Hopefully this information helps someone find what they're looking for.