[FFmpeg-user] Crop, Scale, Pad without distortion

[Hans Carlson]

On Mon, 27 Jan 2020, Carl Eugen Hoyos wrote:

> Am Mo., 27. Jan. 2020 um 03:27 Uhr schrieb Hans Carlson <forbyta at gmx.com>:
>
>> Is 16/9 the correct value for setdar since that's what I want it to end 
>> up to be?
>
> Apparently not but it is what you told us you'd like. (I did not 
> calculate myself)

OK... perhaps I don't know WHAT dar I want.  I plan to concat this video 
to some others (using concat protocol or demuxer) and the other videos 
have a DAR of 16:9, eg:

   Stream #0:0[0x1e0]: Video: mpeg2video (Main), yuv420p(tv, top first), 720x480 [SAR 32:27 DAR 16:9], Closed Captions, 29.97 fps, 29.97 tbr, 90k tbn, 59.94 tbc

So, based on that, I assumed it would be a good idea to match the aspect 
ration (720x480) and the DAR.

If the DAR value doesn't matter when concat'ing multiple files, then I just 
want the video to LOOK correct.

How do I calculate the correct dar (and/or sar) values to use?