Convert audio to 320kbps CBR .mp3, convert video to x264 .mp4

transcode

#!/usr/bin/env bash
#
# Usage:
#     transcode filename [filename...]
#
# File type is determined using:
#
#   file --mime-type filename
#
# Audio files:
#   Audio: anything -> 320kbps CBR MP3
#   Output: .mp3 alongside the source file(s)
#
# Video files:
#   Video: anything -> x264
#   Audio: copy
#   Output: .mp4 alongside the source file(s)
# 
# Anything else is ignored
#
# I live here: https://gist.github.com/datashaman/6866879e4ad07b0483e6efd9ea49d8a2
#
trap 'exit -1' INT

BINARY=ffmpeg
BITRATE=320k
CRF=23
PRESET=slow

for INPUT in "$@"
do
    MIME_TYPE=$(file -b --mime-type "${INPUT}")
    DIRNAME=$(dirname "${INPUT}")
    BASENAME=$(basename "${INPUT}")
    # EXTENSION="${BASENAME##*.}"
    FILENAME="${BASENAME%.*}"

    if [[ $MIME_TYPE == audio* ]]; then
        OUTPUT="${DIRNAME}/${FILENAME}.mp3"
        $BINARY -i "${INPUT}" -vn -ab ${BITRATE} "${OUTPUT}"
    elif [[ $MIME_TYPE == video* ]]; then
        OUTPUT="${DIRNAME}/${FILENAME}.mp4"
        $BINARY -i "${INPUT}" -c:v libx264 -preset ${PRESET} -crf ${CRF} -c:a copy "${OUTPUT}"
    fi
done

rad

Updated to add autodetection of input file type, and transcoding of audio files to 320kbps CBR MP3s.