How to compress video and mp3 file with ffmpeg command under Linux?

 How to compress video file by using ffmpeg:

ffmpeg -i input.mp4 -c:v libx264 -vf scale=640:360 -r 23.98 -b:v 498k -c:a copy output.mp4

or

ffmpeg -i input.mp4 -c:v libx264 -vf scale=640:360 -r 23.98 -b:v 498k -c:a aac -b:a 128k output.mp4

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How to compress audio file by using ffmpeg:

ffmpeg -i input.mp3 -b:a 128k output.mp3