ffmpeg arguments used for converting to mp4

Solution 1:

ffmpeg duplicates syntax. Except for the values used, and that the first command set the sampling rate instead of using the default, the commands are effectively the same:

 -loglevel panic  - merely makes ffmpeg less noisy in the shell
 -vcodec copy     = -c:v copy
 -acodec copy     = -c:a copy   # unlisted in the command, but listing here to show there is consistency
 -ab              = -b:a

Note: The other answer info is correct.

There is a guide online; it lists what every possible argument means.

Solution 2:

The three flags ask for a 2 channel, 48000 Hz sampled, 160k bit rate encoded audio track.

The flags that can be passed to ffmpeg are listed in the ffmpeg manual page. Manual pages tend to be terse but informative:

ac

-ac channels

Set the number of audio channels (default = 1).

ar

-ar freq

Set the audio sampling frequency (default = 44100 Hz).

ab

-ab bitrate

Set the audio bitrate in bit/s (default = 64k).