From 5:4 to 4:3

[Selur]

Here's what I did:

• Started Hybrid
  
• Loaded the source.
  
• Looked at it. It has a SAR of 720x576 and a PAR of 1:1. Since 1:1 PAR is rather uncommon, I suspect that the content should be 1150/1053 (analog PAL with a DAR of 4:3).
  
• Since the input is interlaced, but not flagged as interlaced, I checked whether it's tff or bff. tff has fuild motion when bobbed, so it's tff.
  
• Additionally, I cropped the black bars, distortions.
  

With this I created: par_1150_1053.mp4 and par_1150_1053.mkv using x264 as format like you did in the debug output.
Muxing calls used were:

mkvmerge --ui-language en -o "G:\Output\2023-06-15@16_46_50_3010__03.mkv" --global-tags "G:\Output\mkvtags_2023-06-15@16_46_50_3010__03.xml" -d 0 --default-track 0:yes --default-duration "0:50/1fps" --aspect-ratio-factor 0:1150/1053 --fourcc 0:MP4V --no-chapters --compression -1:none --forced-track 0:yes --field-order 0:0 --no-audio --no-subtitles "G:\Output\2023-06-15@16_46_50_3010_02.264"

and

MP4Box -par 1=1150:1053 -add "G:\Output\2023-06-15@16_47_01_0110_02.264"#video:fps=50:name="":lang="" -brand avc1 -itags tool="Hybrid 2023.06.15.1" -tmp "G:\Output" -new "G:\Output\2023-06-15@16_47_01_0110__03.mp4"

both tell the muxer that the PAR should be 1150:1053.

For the mkv 'mediainfo --full' reports:

Width                                    : 692
Width                                    : 692 pixels
Height                                   : 568
Height                                   : 568 pixels
Stored_Width                             : 704
Stored_Height                            : 576
Sampled_Width                            : 692
Sampled_Height                           : 568
Pixel aspect ratio                       : 1.331
Original pixel aspect ratio              : 1.092
Display aspect ratio                     : 1.621
Display aspect ratio                     : 16:10
Original display aspect ratio            : 1.331
Original display aspect ratio            : 4:3

for the mp4 'mediainfo --full' reports:

Width                                    : 692
Width                                    : 692 pixels
Height                                   : 568
Height                                   : 568 pixels
Stored_Width                             : 704
Stored_Height                            : 576
Sampled_Width                            : 692
Sampled_Height                           : 568
Pixel aspect ratio                       : 1.092
Display aspect ratio                     : 1.329
Display aspect ratio                     : 4:3
Original display aspect ratio            : 1.331
Original display aspect ratio            : 4:3

So yes, something is amiss here.
=> I'll ask the author of mkvmerge about this. (https://forum.doom9.org/showthread.php?p...ost1988463)

It seems to work fine if I use ffmpeg for muxing mkv files, to enabling 'Config->Containers->MKV->FFmpeg for .mkv muxing' should work as a workaround until I manage to figure out what is going wrong with mkvmerge.

Cu Selur

Ps.: I didn't notice this since I usually use PAR 1:1 output.