After capturing some gameplay footage from an SD video capture device, I tried adding it as a clip in Kdenlive 15.12.1, and immediately noted a regression in how the aspect ratio of the clip is handled.

The SD capture device is a Dazzle DVC100 (em28xx-based device). I used mencoder to grab the video. The captured video has a frame dimension of 720*480 pixels, but incorrectly describes the pixel aspect ratio as 1:1 (I don't know if this is a bug in mencoder or the em28xx driver). Since the project has an output frame size of 640*480, Kdenlive would letterbox the video.

Previously, I handled this by going in to the clip properties and forcing the clip's aspect ratio to 4:3. However, that has stopped working in Kdenlive 15.12.1. In fact it vertically squashes the clip even more.

To make a long story slightly shorter and more informative: I saved off a still frame from the original, uncorrected clip, and loaded it into GIMP. The image size was 640*480, but had transparent borders (letterboxing) at the top and bottom of the image. There were 26 missing pixels at the top, 27 missing at the bottom. 480 - 26 - 27 == 427. So I went into the clip properties again and forced an aspect ratio of 480:427. This made the clip fit the frame perfectly. (After playing with the math some more, I realized that 720/640 == 1.125 (9/8), and 480/1.125 == 426.666, which pretty much exactly what I'm seeing.)

So, while I have a workaround, it is not the same as past behavior -- certainly not as it was in the 0.9.x series. Is "force aspect ratio" now expecting a pixel ratio rather than a whole-frame ratio?

I've seen a bunch of fixes yesterday for source aspect ratio differing from 1:1. Can you please try a recent Kdenlive from git master to see if your bug has been fixed?

In the meantime, you could try playing with dsize, and aspect settings in mencoder so you don't have to correct in kdenilve?

And for existing footage, you could always transcode to 640x480 1:1 losslessly.