ffmpeg

replace-audio.sh

#!/bin/bash

set -e

EXAMPLE_USAGE="$(basename $0) video.mp4 audio.mp3 merged.mp4"

if [ -z "$1" ]; then
  echo "please specify input video file"
  echo "$EXAMPLE_USAGE"
  exit 1
fi

if [ -z "$2" ]; then
  echo "please specify input audio file"
  echo "$EXAMPLE_USAGE"
  exit 1
fi

if [ -z "$3" ]; then
  echo "please specify output file"
  echo "$EXAMPLE_USAGE"
  exit 1
fi

ffmpeg -i "$1" -i "$2" -map 0:v -map 1:a -c:v copy -shortest "$3"