MKV to DolbyVision MP4

dv_remuxer.py

#!/usr/bin/env python

import argparse
import subprocess
import json
from pathlib import Path

CODEC_TO_EXT = {
    'MPEG-H/HEVC/h.265': 'h265',
    'VC-1': 'vc1',
    'AC-3': 'ac3',
    'TrueHD Atmos': 'atmos',
    'HDMV PGS': 'pgs',
    'DTS-HD Master Audio': 'dts'
}


def track_name(track):
    t_id = track['id']
    t_lang = track['properties']['language']
    t_codec = track['codec']
    return '{0}_{1}.{2}'.format(t_id, t_lang, CODEC_TO_EXT[t_codec])

def make_extract_tracks_cmd(in_file, tracks):
    cmd = ['mkvextract', in_file, 'chapters', 'chapters.xml', 'tracks']
    for track in tracks:
        t_id = track['id']
        cmd += ['{}:{}'.format(t_id, track_name(track))]
    return cmd

def make_mux_cmd(out_file, tracks):
    cmd = ['mp4muxer', '--dv-profile', '7', '--output-file', out_file]
    # video tracks are first, sort them by size?
    for track in filter(is_video, tracks):
        cmd += ['--input-file', track_name(track)]
    # then all ac3 tracks
    for track in filter(is_audio, tracks):
        t_lang = track['properties']['language']
        cmd += ['--input-file', track_name(track),
                '--media-lang', t_lang]
    return cmd

def is_video(track):
    return track['type'] == 'video'

def is_audio(track):
    return track['type'] == 'audio'

def is_lang(track, languages):
    return ('properties' in track and
            track['properties']['language'] in ['und'] + languages)

def main():
    parser = argparse.ArgumentParser()
    parser.add_argument('input', nargs=1, type=str)
    parser.add_argument('--keep-audio-lang', nargs='+', default=None)
    cmd = parser.parse_args()

    for file in cmd.input:
        info = subprocess.run(['mkvmerge', '-J', file], capture_output=True)
        if info.returncode == 0:
            info = json.loads(info.stdout.decode('utf-8'))                
            tracks = info['tracks']
            # must have 2 video tracks
            if len(list(filter(is_video, tracks))) < 2:
                raise Exception('2 video tracks are needed for Dolby Vision mux')
            # filter audio audio tracks
            tracks = list(filter(lambda t: is_lang(t, cmd.keep_audio_lang) or not is_audio(t),
                                tracks))
            extract_cmd = make_extract_tracks_cmd(file, tracks)
            print(extract_cmd)
            out_file = Path(file).stem + '.mp4'
            remux_cmd = make_mux_cmd(out_file, tracks)
            print(remux_cmd)
            subprocess.run(extract_cmd)
            subprocess.run(remux_cmd)
            print('cleaning up...')
            for track in tracks:
                t_file = Path(track_name(track))
                if t_file.exists():
                    Path(track_name(track)).unlink()
                else:
                    print('{} is already gone'.format(t_file.as_posix()))
            print('done: {}'.format(out_file))
        
if __name__ == "__main__":
    main()

Hi,

The topic looks interesting but I can't seem to get it to run. Do you have to edit that python file based on the title of the .mkv somehow?

Hi,

The topic looks interesting but I can't seem to get it to run. Do you have to edit that python file based on the title of the .mkv somehow?

You need to have the mkvtoolnix and dlb_mp4base from dolby labs in the path.