Combining videos with different aspect ratios in an MKV

[wallywalters]

I've got DVD of old sitcoms whose episodes were shot in the 4x3 aspect ratio but preceded by a new intro clip by the star, shot 16x9. I'd like to encode both to x264 and put them in the same MKV container, with each keeping its original aspect ratio. I've tried making a few test files and appending episode-to-intro in MKVToolNix, and while it seems MKVToolNix doesn't alter the ratios, whichever video appears "first" in the file is the aspect ratio displayed in the output. Ideally, playback would show both in their correct size. Is there a way to do this?

edited: I guess another way to put it is, can different chapters have different aspect ratios?

[manono]

Make the 4:3 DVDs the same resolution as the 16:9 one. You do this by resizing the 4:3 DVD videos to whatever 1.33:1 ratio is appropriate (for example, 640x480) followed by adding black bars to the sides to bring them up to the same ratio and resolution as the 16:9 one when resized. If, when resized the 16:9 one is 854x480, then you add a total of 214 columns of black to the sides of the 640x480 ones (208 and 206, for example) to make them also 854x480.

I guess another way to put it is, can each MKV chapter be displayed in a different aspect ratio?

Since you're reencoding everything anyway (right?) I don't know why that would be a requirement.

[sneaker]

Matroska display resolution is per track, not per chapter. To work around either:
a.) resize into to 4:3 (with black bars)
b.) put into different Matroska files and append using file linking ("simple" linking or ordered chapters)
c.) encode while setting correct --sar for each, then append in mkvmerge

Whether b and c are successful depends on the player so I would probably go with solution a like manono suggested. Intros aren't all that important anyways IMHO.

[wallywalters]

Thanks, guys.