transcode.py

#! /usr/bin/python
""" Depends on ffmpeg and MP4Box. This scripts accepts a HD video and creates different
bitrate versions for dash
@author : Hrishikesh Bhaskaran <hrishi.kb@gmail.com>, May 2019
"""
import os
import sys
from xml.dom import minidom

config = {
    "keyint": "59",
    "framerate": "30000/1001",
    "profile": "onDemand",
    "chunk": "1000",
}
base_filename = None
# pre-defined resolutions
versions = ["256", "426", "854", "1280", "1920"]

files_to_clean = []


def create_multiple_bitrate_versions(filename):
    for version in versions:
        command = 'ffmpeg -i {} -vf "hqdn3d,detelecine,yadif,scale={}:-2" -x264-params "keyint={}:min-keyint={}:no-scenecut" -b:a 50k -strict -2 -preset veryfast -crf 25 -r {} {}/{}-{} -y'.format(
            filename,
            version,
            config.get("keyint"),
            config.get("keyint"),
            config.get("framerate"),
            base_filename,
            version,
            filename,
        )
        print(command)
        os.system(command)


def create_multiple_segments(filename):
    os.chdir(base_filename)
    base_command = "MP4Box -dash {} -frag {} -rap -frag-rap -profile {} {} {}-{}{}"
    for version in versions:
        command = base_command.format(
            config.get("chunk"),
            config.get("chunk"),
            config.get("profile"),
            "-out " + version + "-" + base_filename + ".mpd",
            version,
            filename,
            "#video",
        )
        print(command)
        os.system(command)
        files_to_clean.append(
            base_filename + "/" + version + "-" + base_filename + ".mpd"
        )
    command = base_command.format(
        config.get("chunk"),
        config.get("chunk"),
        config.get("profile"),
        "-out audio.mpd",
        versions[0],
        filename,
        "#audio",
    )
    print(command)
    os.system(command)
    files_to_clean.append(base_filename + "/" + "audio.mpd")
    os.chdir("..")


def merge_mpds(mpd_file_name):
    root = None
    for mpd in files_to_clean:
        if not root:
            root = minidom.parse(mpd).documentElement
            continue
        period_element = root.childNodes[3]
        current_mpd_root = minidom.parse(mpd).documentElement
        adaption_set = current_mpd_root.childNodes[3].childNodes[1]
        period_element.appendChild(adaption_set)
    with open(base_filename + "/" + mpd_file_name, "w") as f:
        f.write(root.toxml())


if len(sys.argv) == 1:
    print("Enter the filename")
else:
    filename = sys.argv[1]
    if " " in filename:
        new_name = filename.replace(" ", "-")
        os.rename(filename, new_name)
        filename = new_name
    mpd_file_name = filename.replace(".mp4", ".mpd")
    base_filename = filename.split(".")[0]
    # create output file directory
    try:
        os.mkdir(base_filename)
    except FileExistsError:
        pass
    create_multiple_bitrate_versions(filename)
    create_multiple_segments(filename)
    merge_mpds(mpd_file_name)
    # cleanup
    for file_name in files_to_clean:
        print("rm " + file_name)
        os.remove(file_name)