convert audio to video using bash script with ffmpeg

audio2mp4.sh

#!/usr/bin/env bash

# Author: crischutu07
# Usage: audio2mp4.sh <audio.mp3> [output.mp4] [cover.jpeg]

# NOTE: albumimg variable is temporary
if [ -f "$3" ]; then
  basefilename=$(basename -- "$3")
  if [[ ! $basefilename =~ .*\.(jpg|jpeg) ]]; then
    ffmpeg -i "$3" "${basefilename%.*}.jpg" || {
      echo "Failed to convert non-jpeg file to jpeg!"
      exit 2
    } &&
      albumimg="${basefilename%.*}.jpg" 
  else 
    albumimg="$3"
  fi
  unset basefilename
else
  # embedded album cover in audio files tend to use
  # JPEG format.
  albumimg="$(mktemp --suffix=.jpg)"
fi

audio="$1"
output="$2"

if [ ! -f "$audio" ]; then
  echo "Requires an input file (Highly recommend using 'opus' or 'mp3' audio file for MP4!)"
  exit 1
elif [[ ! $audio =~ .*\.(mp3|wav|opus|flac|ogg|m4a|aac|3gp|oga|mogg|webm|aiff) ]]; then
  echo "Not an audio file."
  exit 1
fi

if [ -z "$output" ]; then
  basefilename="$(basename -- "$audio")"

  output="${basefilename%.*}.mp4"
  echo "No file output! Defaulting to: ${output}"
  unset basefilename
fi

if [ ! -f "$3" ]; then
  ffmpeg -i "$audio" \
    -an \
    -vf "scale=1024:-1" \
    "$albumimg" -y || { 
    echo -e "Failed to run FFmpeg, make sure the audio file contains embedded album cover.\nOr manually specify it by running:\n=> $(basename -- "$0") \"$1\" \"$output\" cover.jpg (Where 'cover.jpg' is the album cover!)"
    [ -z "$3" ] && rm "$albumimg"
    exit 1
  }
fi

ffmpeg -loop 1 \
  -i "$albumimg" \
  -i "$audio" \
  -c:a copy \
  -c:v libx264 \
  -profile:v high \
  -preset ultrafast \
  -map_metadata 1 \
  -ac 2 \
  -crf 20 \
  -pix_fmt yuv420p \
  -tune stillimage \
  -r 15 \
  -shortest \
  -y "$output"

[ -z "$3" ] && rm "$albumimg"

read -r -p "Save option (catbox,open,delete): " saveoption
case "$saveoption" in
  catbox) if command catbox; then
	   catbox file "$output"
	  else
	    echo "You don't have catbox installed on PATH."; exit 2
	  fi;;
  open) termux-open "$output" && exit 0;;
  delete) rm "$output" && echo "Deleted $output"; exit 0;;
  *) exit 0;;
esac

unset output albumimg audio output saveoption