Allow arbitrary DAR for containers

[guju]

See https://avidemux.org/smif/index.php?msg=98289

DAR:
Some typical values,
arbitrary value,
"keep" (orig DAR).

[therube]

Well you can do that, in a round about way - perhaps*.

*Perhaps, depending on Output Format.  Like mp4, mkv, but not flv...


Output Format
Configure -> Force aspect ratio --> Derived from display width


At that point, you need to set the Display Width to a number that "works".

In a recent video, output A/R was coming out wrong, & that had to do with the (oh, I'll probably get the terminology wrong, but...) DAR.
The DAR was weird.  So I took the expected Display Width, then divided that by the DAR (as reported by MediaInfo).

(I think that was the deal.)

So lets say Media Info showed DAR to be 1.3 (non-square pixels or whatnot).
So I took the expected Display Width, say 480, then divided that by 1.3, & used that value, 369, as the Display Width setting in Avidemux.

With that the output file A/R was as wanted (or at least close enough, given rounding).


(Again, I may have terminology wrong, or my numbers could be wrong, but the basic premise did work out.)

[therube]

And in that respect, I was thinking of a setting in Avidemux, something like:

Derived from display width, adjust by DAR

That would go out, see that non-square pixels exist, & do the computation automatically...