add-audio-to-video.sh

   1 #!/bin/sh
   2
   3 input_video=$1
   4 input_audio=$2
   5
   6 if [[ -z "$1" ]] || [[ -z "$2" ]]
   7 then
   8         echo Invalid input
   9         echo "\"$0 <input video> <input audio>\""
  10         exit 1
  11 fi
  12
  13 tmp_video=tmp$$.mp4
  14
  15 function get_duration() {
  16         ffmpeg -i $1 2>&1 | \
  17                 awk -F, '/Duration/{print $1}' | \
  18                 awk -F: '{print $2*3600 + $3*60 + $4}'
  19 }
  20
  21 duration_audio=`get_duration $input_audio`
  22 echo Duration of audio is $duration_audio seconds
  23
  24 duration_video=`get_duration $input_video`
  25 echo Duration of video is $duration_video seconds
  26
  27 av_ratio=$(echo "2k $duration_audio $duration_video / p" | dc)
  28 echo Calculated audio/video ratio is $av_ratio
  29
  30
  31 # make video about the same length as the audio
  32 ffmpeg \
  33         -i $input_video \
  34         -filter:v "setpts=${av_ratio}*PTS" \
  35         $tmp_video
  36
  37 # adds audio to video,
  38 # compresses audio
  39 ffmpeg \
  40         -i $tmp_video \
  41         -i $input_audio \
  42         -c:v copy \
  43         -map 0:v:0 \
  44         -map 1:a:0 \
  45         -c:a aac \
  46         -b:a 192k \
  47         output.mp4
  48
  49 [[ -f $tmp_video ]] && rm $tmp_video