# mux audio into containers. file names in sound and current dirrectories must match. tmp usage for anime downloads.
# usage: ffmpeg_mux_audio <SOUND> <OUTPUT DIR>
ffmpeg_mux_audio()
{
  if [[ "$1" = "" ]]; then
    echo "usage: ffmpeg_mux_audio <SOUND> <OUTPUT DIR>"
    return 2
  fi

  for file in *; do ffmpeg -i "$file" -i "$1"/"$file" -c copy -map 0:v:0 -map 1:a:0 -shortest "$2"/"$file"; done
}

# Mux cover into music file.
# Usage: ffmpeg_mux_cover <FORMAT> <COVER>
ffmpeg_mux_cover()
{
  if [[ "${1}" = "" ]]; then
    echo "Usage: ffmpeg_mux_cover <FORMAT> <COVER>"
    return 2
  fi

  local format="${1}"
  local cover="${2}"

  mkdir out

  for file in *.${format}; do
    ffmpeg -i "${file}" -i "${cover}" -map 0:a -map 1 -codec copy -metadata:s:v title="Album cover" -metadata:s:v comment="Cover (front)" -disposition:v attached_pic ./out/"${file}" || return 1
  done

  mv out/* .
  rm -d out/ && rm "${2}"
}

# Change music metadata.
# Usage: ffmpeg_music_meta <FORMAT>
ffmpeg_music_meta()
{
  if [[ "${1}" = "" ]]; then
    echo "Usage: ffmpeg_music_meta <FORMAT>"
    return 2
  fi

  local format="${1}"

  ls *.${format} &> /dev/null || return 1

  local artist="${PWD%/*}"; artist="${artist##*/}"; artist="${artist//_/ }"
  local album="${PWD##*/}"; album="${album#*_}"; album="${album//_/ }"
  local year="${PWD##*/}"; year="${year%%_*}"

  mkdir out

  for file in *.${format}; do
    local track="${file%%_*}"; track=$((10#${track})); [[ "${track}" = "" ]] && track=0
    local title="${file#*_}"; title="${title%.*}"; title="${title//_/ }"

    # echo "${artist}; ${album}; ${year}; ${track}; ${title}"
    ffmpeg -i "${file}" -c copy -metadata "artist=${artist}" -metadata "album_artist=${artist}" -metadata "album=${album}" -metadata "date=${year}" -metadata "year=${year}" -metadata "track=${track}" -metadata "title=${title}" ./out/"${file}" || return 1
  done

  mv out/* .
  rm -d out/
}

_ffprobe_fps()
{
  local fps=$(ffprobe -v 0 -of csv=p=0 -select_streams v:0 -show_entries stream=r_frame_rate "${1}")
  fps="${fps%%/*}"
  echo "${fps}"
}

_ffprobe_keyint()
{
  local fps=$(_ffprobe_fps "${1}")
  echo $((fps*5))
}

_ffprobe_ba()
{
  local ba=$(ffprobe -v error -select_streams a:0 -show_entries stream=bit_rate -of default=noprint_wrappers=1:nokey=1 "${1}")
  [[ "${ba}" != "N/A" ]] && echo $((ba/1024)) || echo 128
}

export -f _ffprobe_keyint _ffprobe_ba _ffprobe_fps