replace audio in video files without re-encoding

replace-audio.sh

#!/bin/sh

# replace audio in a video file without re-encoding the video
# based on https://superuser.com/a/1096239

# CLI usage: ./replace-audio.sh video.mp4 audio.mp4 output.mp4
# interactive usage: run script, enter filenames when asked, confirm with ENTER

function run() {

  local input_video="${1}"
  if [ -z "$input_video" ]; then
    echo ">> input video"
    read input_video
  fi

  local input_audio="${2}"
  if [ -z "$input_audio" ]; then
    echo ">> input audio"
    read input_audio
  fi


  local output_video="${3}"
  if [ -z "$output_video" ]; then
    echo ">> output video"
    read output_video
  fi

  ffmpeg.exe -i $input_video -i $input_audio -vcodec copy -map 0:0 -map 1:0 $output_video
}

run "$@"

run.sh

#!/bin/sh

mkdir -p ./out
mkdir -p ./out/mobile

./replace-audio.sh ./in/video/intro.mp4 ./in/audio/intro_stretched.wav ./out/intro.mp4
# ...

./replace-audio.sh ./in/video/mobile/intro.mp4 ./in/audio/intro_stretched.wav ./out/mobile/intro.mp4
# ...