FFmpeg - Metadata

Strip All Metadata

ffmpeg -i <input.file> -map_metadata -1 -fflags +bitexact -flags:v +bitexact -flags:a +bitexact -f mp4 <output.file>

Add Title Tag

ffmpeg -i <input.file> -metadata title="flibble" -f mp4 <output.file>

Add Year Tag

ffmpeg -i <input.file> -metadata date=0 -f mp4 <output.file>

Add Language Tags

ffmpeg -i <input.file> -metadata:s:a:0 language=eng -metadata:s:v:0 language=eng -f mp4 <output.file>

Set Default Track

Reference: FFmpeg - Encoding Optimal Videos for Streaming