Video 720x576 horizontally compressed?

[avilon]

Music video from 1970-1980 period 720x576 (PAL?) playing horizontally compressed and ratio looks distorted like 576x576. All other mkv tracks from same author collection play normally.

Should I HEVC x265 re-encode track?
But how to maintain 720x576 resolution?
I guess there is some option to force pixels to horizontal rectangles instead square?
But how? Thanks.

[eumagga0x2a]

Do you refer to the way the source video is displayed in a dedicated video player (which should display a video at pixel aspect ratio provided by the container and/or by the codec) or to the specific way Avidemux displays all videos (always with square pixels)?

In general, you might be able to fix the video by saving it in copy mode, again as MKV, with display aspect ratio in the configuration of the MKV muxer set to a value which fits the expected proportions best.

For a more substantiated answer, please provide Avidemux log (admlog.txt from %localappdata%\avidemux\ on Windows, else the stdout output of Avidemux executable run in a terminal) from starting Avidemux, loading the source video and closing Avidemux.

[avilon]

Vlc player plays this clip in square 576x576 format (distorted), when clip properties in vlc player state 720x576.
Attempts to change mkv configuration settings and save copy doesn't have any effect.

admlog attached.

[avilon]

My bad. As there is so many amorphous video ratio related problems, I forgot to check ...
For unknown reason this old collection has one track in amorphous mode horizontally compressed and to achieve 720 pixel width there are black stripes on both sides, which is difficult to realize on any wider screen.

Solution:
With Avidemux I HEVC x265 re-encode cropped track to 576 pixel width (omitting black).
Then I opened this new track and just used mkv copy with "force 720 width" and done.

Thanks for attempts to help me.

[eumagga0x2a]

You are using Avidemux 2.7.5 which is an entirely unsupported old version (only the latest 2.8.2 nightly or at worst the latest release are supported).

The stream is indeed a standard 720x576 MPEG-2, so if it had been messed up by including added vertical black bars, you had two options: preserving quality and achieving the right proportions for the content of the video by forcing a custom width much larger than 720 (maybe 1024?) pixels in the MKV muxer and probably accepting black bars all around or the way you solved the problem, fixing the aspect by cropping black bars and resizing the picture (and losing quality by re-encoding).