burnSubs.sh

#!/bin/bash

##### Variable: $burnSubs_usage ###############################################
burnSubs_usage="
  Usage:
    ./burnSubs <Video File> [<Subtitle File>] [<Output File>]

  Examples:
    To burn in file-embedded subtitles:
      ./burnSubs <Video File>

    To burn in external subtitles:
      ./burnSubs <Video File> <Subtitle File>

    The default output filename is:
      <Video File>.subtitled.mp4


"


##### Required Argument 1 #####################################################
if [ -z "$1" ]
    then
        echo "Error: Missing required first argument."
        echo "$burnSubs_usage"
        exit 99
fi


##### Variable: $VIDEO_SOURCE #################################################
VIDEO_SOURCE=$1

if [ -z "$2" ]
    then
        SUBTITLE_SOURCE=$VIDEO_SOURCE
    else
        SUBTITLE_SOURCE=$2
fi


##### Variable: $OUTPUT_FILENAME ##############################################
if [ -z "$3" ]
    then
        OUTPUT_FILENAME="${VIDEO_SOURCE}.subtitled.mp4"
    else
        OUTPUT_FILENAME=$3
fi


##### Variable: $SUBTITLE_SETTINGS ############################################
SUBTITLE_SETTINGS="force_style='FontName=Arial'"



##### Variable: $VIDEO_SOURCE #################################################
VIDEO_SOURCE_ESCAPED=$(printf '%q' "$VIDEO_SOURCE")



##### Variable: $SUBTITLE_SOURCE ##############################################
SUBTITLE_SOURCE_ESCAPED=$(printf '%q' "$SUBTITLE_SOURCE")



##### Variable: $OUTPUT_FILENAME ##############################################
OUTPUT_FILENAME_ESCAPED=$(printf '%q' "$OUTPUT_FILENAME")


##### FUNCTION: Prepare temp data file ####
if [ -f "tmp.dat" ];
    then
        rm "tmp.dat"
fi
touch "tmp.dat"


##### FUNCTION: Resize Video if too big ####
`ffmpeg -i "${VIDEO_SOURCE}" 2> tmp.dat`

if grep -q " Video: " tmp.dat
    then
        RESOLUTION=`grep " Video: " tmp.dat`
        RESOLUTION=`echo $RESOLUTION | sed -En 's/.* [0-9][0-9]+x([0-9]+) .*/\1/p'`
        echo $RESOLUTION
        if [[ $RESOLUTION -gt 720 ]];
            then
                ffmpeg -y -i "${VIDEO_SOURCE}" \
                    -c:v libx264 \
                    -crf 25 \
                    -vf subtitles="${SUBTITLE_SOURCE}":${SUBTITLE_SETTINGS},scale=-2:480 \
                    "${OUTPUT_FILENAME}"
            else
                ffmpeg -y -i "${VIDEO_SOURCE}" \
                    -vf subtitles="${SUBTITLE_SOURCE}":${SUBTITLE_SETTINGS} \
                    "${OUTPUT_FILENAME}"
        fi
    else
    #   cat tmp.dat
        echo "ERROR: Unable to read source video \"$VIDEO_SOURCE\""
        exit 99
fi

if [ -f "tmp.dat" ];
    then
        rm "tmp.dat"
fi