Depending on your country, the website you're uploading to and your usage of both audio and video, the copyright-laws make it legal or illegal to use a specific song.
If you create a video-essay about music-production and must use the song as an example to show your point, you will, in many cases and places not break any laws. If you combine a still-image ...
If I was doing this for a video production, I would use After Effects, and import the GPX track from a GPS device into a mapping plugin like GeoLayers:
I personally use RaceRender, however, there is also DashWare.
Both can edit video and add GPS position overlays.
Bare in mind, neither of them can add the actual "map" like one from Google Maps, just a line showing your path and a marker showing the current location.
Again, my personal preference is to use RR or DW to produce a video with a magenta ...
There are a couple of things which you may still tune in the x264 encoder like listed here but also in the mp3 decoder like shown here if you are OK with a lower audio bitrate.My assumption is that not everything is eaten up by the video.
I have tried
ffmpeg -loop 1 -y -i image.jpg -i audio.ogg -shortest -acodec mp3 -qscale:a 7 -vcodec libx264 -preset ...
I am not sure your output stream video and audio distributions, let's assume the output size is mostly occupied by the video ES.
In the H.266 era, x265 is not a new codec
!ffmpeg -y -i https://github.com/Matroska-Org/matroska-test-files/raw/master/test_files/test5.mkv -c:v libx265 -an VideoOnly_265.mp4
The file size of VideoOnly_265.mp4 is
-rw-r--r-- 1 ...