16:9 AR and 1440x1080 video

[flapane]

I have a camera (sony a6000) which can record widescreen MP4 videos at 1440x1080 (I guess the pixels are rectangles and not squares).
If I encode the video using Avidemux, the result file has a wrong aspect ratio (1:1.33), and I need to fix the issue by selecting 16:9 AR in MKVMerge.
Any way to set the AR flag in Avidemux, without using any transform filters?
Thanks in advance

[zakk]

MKV container + Configure button with force display width 1920 pixels

[flapane]

Thanks!