[cool advertise]

Originally Posted by Nico8583

No problem, I think the job should be do by the muxer, this is why I asked to cool advertise to try it
When the muxer does the job, it could analyze the max values for each M2TS and keep the higher values as default value ?!
But the values will be wrong for 3 or all M2TS segments, so is it useful to use that when encoding to x265 ?

I opened a issue on gitlab, to the mkvtoolnix developer Moritz Bunkus, proposing to read this discussion and provide an opinion.
Here is his answer:

Metadata such as pixel dimensions or HDR metadata can change mid-stream. That's simply a limitation, same as in MPEG transport streams (e.g. when content in a DVB stream changes between HD and SD content, which is where pixel dimensions change, or even between different shows, where encoder setting change). Players just have to cope with that — and they already do. A Blu-ray player reading a playlist of multiple M2TS already has to deal with changing HDR metadata between the different M2TS files, for example, and for other content VLC, MPC-HC and all the other players can already deal with changing pixel dimensions within the same stream.
About modifying HDR metadata during muxing: that's not MKVToolNix' job, nor is it in the scope of this project (it's not a video mastering application). It would only be possible for certain metadata values anyway (the Max* values, for examples), but not for others.
No bug here.

With this I don't want to go into the subject further.