Convert QL Video to MP4

convert.sh

#!/bin/bash

function file_extension {
    local filename=$(basename "$1")
    echo "${filename##*.}"
}

function basename_test {
    echo $(basename "$1" .qt)
}

function decide_video_codec_from_extension {
    if [ "$1" == "mp4" ]
    then
        echo "libx264"
    elif [ "$1" == "webm" ]
    then
        echo "libvpx" # or libvpx-vp9
    else
        echo "" 1>&2
        echo "Unknown video extension; supported are: mp4 webm" 1>&2
        kill -INT $$
    fi
}



for F in *.qt;
do

    OUTPUT_FILE=$(basename_test $F)
    OUTPUT_FILE="$OUTPUT_FILE.mp4"

    # decide which codec to use based on extension
    OUTPUT_EXTENSION=$(file_extension ${OUTPUT_FILE})
    FFMPEG_ARG_VIDEO_CODEC=$(decide_video_codec_from_extension ${OUTPUT_EXTENSION})

    echo "Format: ${OUTPUT_EXTENSION} (${FFMPEG_ARG_VIDEO_CODEC})"

    # read video duration (in miliseconds) from file
    SOURCE_LENGTH_MS=`mediainfo --Inform="General;%Duration%" "${F}"`
    echo "Video length: $((${SOURCE_LENGTH_MS} / 1000)) seconds"

    # read desired file size from stdin
    echo ""
    echo -n "Target size in MB: "
    SIZE=$(stat -f%z "$F")
    # TODO: Need better handler over size.  
    CAL=$(bc -l <<< "scale=0; $SIZE/1024/1024 +1")
    TARGET_MB=$CAL


    # calculate bitrates
    TARGET_KBPS=$((1000 * ${TARGET_MB} * 1024 * 8 / ${SOURCE_LENGTH_MS} - 32))

    AUDIO_KBPS=128
    VIDEO_KBPS=$((${TARGET_KBPS} - ${AUDIO_KBPS}))

    echo "Target video bitrate: ${VIDEO_KBPS} kbps"
    echo "Target audio bitrate: ${AUDIO_KBPS} kbps"

    # build command arguments
    VIDEO_ARGS="-c:v ${FFMPEG_ARG_VIDEO_CODEC} -b:v ${VIDEO_KBPS}k -pix_fmt yuv420p"

    # [ ! -z "${VIDEO_PRESET}" ] && VIDEO_ARGS="${VIDEO_ARGS} -preset ${VIDEO_PRESET}"
    # [ ! -z "${VIDEO_SCALE}" ] && VIDEO_ARGS="${VIDEO_ARGS} -filter:v \"scale=${VIDEO_SCALE}\""
    [ "${FFMPEG_ARG_VIDEO_CODEC}" == "libx264" ] && VIDEO_ARGS="${VIDEO_ARGS} -profile:v baseline -level 3.0 -movflags +faststart"

    AUDIO_ARGS=""
    [ "${OUTPUT_EXTENSION}" == "mp4" ] && AUDIO_ARGS="-c:a aac -b:a ${AUDIO_KBPS}k"
    [ "${OUTPUT_EXTENSION}" == "webm" ] && AUDIO_ARGS="-c:a libvorbis -b:a ${AUDIO_KBPS}k"

    # build and execute commands
    CMD_PASS1="ffmpeg -y -i \"$F\" ${VIDEO_ARGS} -pass 1 ${AUDIO_ARGS} -f \"${OUTPUT_EXTENSION}\" /dev/null"
    CMD_PASS2="ffmpeg -i \"$F\" ${VIDEO_ARGS} -pass 2 ${AUDIO_ARGS} \"${OUTPUT_FILE}\""

    echo ""
    echo "PASS 1 - EXECUTING COMMAND: $CMD_PASS1"
    eval "$CMD_PASS1"

    echo ""
    echo ""
    echo ""
    echo "PASS 2 - EXECUTING COMMAND: $CMD_PASS2"
    eval "$CMD_PASS2"
done