mkv-merge-eng-audio.sh

#!/bin/bash
IFS=$'\n\t'
set -euo pipefail

cd "~/Downloads/series"

function merge() {
  jpnSrc="$1"
  en1Src="$2"
  en2Src="$3"
  out="$4"

  if [[ -f "$out" ]]; then
    return
  fi

  ffmpeg -i "$jpnSrc" -i "$en1Src" -i "$en2Src" -c copy \
    -map_metadata:g -1 \
    -map 0:v:0 -metadata:s:v:0 language="jpn" -disposition:v:0 default \
    -map 2:a:0 -metadata:s:a:0 language="eng" -disposition:a:0 default \
    -map 0:a:0 -metadata:s:a:1 language="jpn" -disposition:a:1 0 \
    -map 0:a:1 -metadata:s:a:2 language="jpn" -metadata:s:a:2 title="Commentary" \
    -map 2:s:0 -metadata:s:s:0 language="eng" -metadata:s:s:0 title="Signs/Songs" -disposition:s:0 forced \
    -map 2:s:0 -metadata:s:s:1 language="eng" -metadata:s:s:1 title="English" -disposition:s:1 default \
    -map 1:s:0 -metadata:s:s:2 language="eng" -metadata:s:s:2 title="English (Animated)" -disposition:s:2 0 \
    -map_chapters 1 \
    -max_interleave_delta 0 \
    "$out"
}

merge "jpn/01[Ma10p_1080p][x265_flac_aac].mkv" \
  "en1/01(1920x1080 Hi10P BD FLAC)mkv" \
  "en2/01[BD_720p_8bit].mkv" \
  "out/01 Bluray-1080p.mkv"