Why doesn't some videos fill the screen when played to a smart tv?

[HeyRicardo]

When I play mp4/aac video clips, ripped from two different tv channels, to my smart tv (FHD) they will fit the screen perfectly (though the files have smaller res).
I just put them on a USB pendrive and with default settings the tv will know how to fit the screen (as if they were FHD res).

So now: after recording an mp4 video on my smartphone, at chosen smaller res 720p, it resulted in portrait mode when played via miracast to the tv (this problem didn't bother me, because I subsequently transcoded it using VLC, to rotate it).
Still, playing the rotated file from USB, it doesn't scale up fullscreen as the former files do.
In other words, the tv does not crop the solid background framing around the actual video (like a centered rectangle).
(via miracast instead, using a specific player, which allows me to landscape the screen, it will be mirrored properly on the tv)

I wonder in what they do differ each other, so as to adjust the conversion process and make it work straightly from USB, as those ripped files do seamlessly.

Any hint about it, or which metadata are relevant to compare, to reveal meaningful differences?
Thanks in advance for helping understand the issue, ricardo

[davexnet]

I don't think any TV will automatically crop out the black if it's part if the file.

Encode it without the black border instead

[HeyRicardo]

When I transcoded using VLC I just set the transformation filter; not aware of what to use/set to avoid black borders (nor aware of whether they are already in the source file, or introduced afterwards).
That's what I'm aiming at.

[davexnet]

Helping to understand exactly what you have would help. Perhaps you could post a few seconds of your source video
here to the forum.
How does it look when you play it on the computer? Normal widescreen with a rotated image inside?

[HeyRicardo]

exactly, rotated 16:9 , I am attaching 10s cut.

[jagabo]

Your video includes black borders. So it is filling the screen but those black borders are part of the picture. If you want the video to fill the screen without black borders cut off the borders before encoding. And make sure the remaining picture is 16:9.

[davexnet]

I used Vidcoder to crop and rotate. Most of the settings in this program can be left as default.

Oops - jagabo beat me to it!

[HeyRicardo]

Thank you both of you, actually, very much indeed.

@davexnet Pointing out which piece of software to use and how to set it up properly was exactly what I was looking for (so I could manage and rotate/crop 5 files for overall 4h30m on time for viewing it today)

[jagabo]

The same can be done with AviDemux and almost every other video editor:

[HeyRicardo]

Very good to know, I'll definitely use it in the future, though I liked so much vidcoder for it let me experiment and gain confidence very easily in doing something for the first time.

What I am thinking about is how to preserve as much as possible the source quality, that is whether I can rotate without lowering resolution.
In source metadata I read w=960 h=544 (which is confusing btw, because the video is rotated when seen on the pc, whereas recorded in landscape mode), so it would be better eventually to come up at least with something like 544x960 (if not straight to fhd res) rather than 308x544.

Not a big problem when the tv is able to interpolate (something like that) and draw a good quality overall, but why degrading a good source (which in my case is not optimized but I tried to set parameters, like bit rate, more than needed probably).

[jagabo]

The picture only occupies a 544x308 portion of the source frame. You can upscale the resulting crop/rotate but that will not create more detail. The best you can hope for is to keep sharp edges without introducing oversharpening halos and aliasing artifacts. It will never look like real high definition video. If you go too far things will start looking very artificial. People will end up up looking like mannequins, etc. You'll need to use advanced scaling algorithms like nnedi3 in AviSynth. In the end, you will get something only a little bit better than your graphics card does when it upscales the small video at playback. And you'll need a much higher bitrate to keep the compression from killing your work.

Bicubic upscale (about what your graphics card will do) and nnedi3,awarpsharp/sharpen upscale in AviSynth attached.

[HeyRicardo]

I see, well, when I recorded I'd set 520p (like those files ripped from tv channel, which I knew being of good enough quality when upscaled), but the problem with orientation in the source file led me to an even smaller frame apparently. I'll try with 720p next time..right now the recording is just enough good as long as I stay a distance away from the tv.
For the post-processing what you say is proved by my subjective impression that the first picture seems even better (though at fine level) that the second..interesting comparison.
Thanks for in-depth explanations and everything.

[jagabo]

Why don't you record with the right orientation so you don't have to crop and rotate?

[HeyRicardo]

That was my goal, unexpectedly it came out with wrong orientation. I'll have to experiment to see, I had no time when I recorded the live stream (I set landscape mode, instead of automatic, thinking it would record that way, but not). I start in portrait browser, go full screen and let the screen auto-rotate.
Probably the app retained the initial orientation nevertheless. Maybe I was supposed to hit record after tilting, and not before anything else.
(I've used DU recorder; also got AZ screen recorder to try). But it was an accident.

Btw, when I crop and rotate is it better to set passthrough codec for audio? I fear that reencoding will worsen it..I overlooked it when using vidcoder.