#!/bin/bash

# complain if no input file given
if [ $# -lt 1 ]; then
    >&2 echo "usage: $0 <input_file>"
    exit 1
fi

# get input video name
input="${1}"
shift 1

# without file extension
output_base="${input%.*}"

# common video resolutions
heights=(240 360 480)
widths=(426 640 854)

# just a quick-and-dirty loop
for index in $(seq 0 2); do
    height="${heights[$index]}"
    width="${widths[$index]}"

    # actual conversion
    ffmpeg -i "${input}" \
        -acodec aac -vcodec h264 \
        -vf "scale=w=${width}:h=${height}:force_original_aspect_ratio=decrease,pad=${width}:${height}:(ow-iw)/2:(oh-ih)/2" \
        "${output_base}_${height}.mp4"
done

exit 0