Python script for downloading the audio of a Youtube video, clipping a certain section of it, adding a slight fade in and out, and saving the clip to a file.

mp3ytclipper.py

#!/usr/bin/python3.5

#example usage: mp3ytclipper.py "https://www.youtube.com/watch?v=MgxK5vm6lvk" later 44.3 46.3

import sys, re, subprocess, youtube_dl, os

if len(sys.argv) != 5:
	print("usage: mp3ytclipper.py <youtubeurl> <outfilename> <starttime> <endtime>")
	exit()

def gettime(timestr):
	parts = timestr.split(":")
	if len(parts) == 2:
		return (int(parts[0]) * 60) + float(parts[1])
	if len(parts) == 1:
		return float(parts[0])
	raise ValueError("Only minutes:seconds supported")

def runcommand(commandarray):
	return subprocess.check_output(commandarray, stderr=subprocess.STDOUT).decode("utf-8")

url = sys.argv[1]
outfile = sys.argv[2] + ".mp3"
start = gettime(sys.argv[3])
duration = gettime(sys.argv[4]) - start

options = {
	'format': 'bestaudio/best',
	'extractaudio' : True,
	'audioformat' : "mp3",
	'outtmpl': 'yt_audio/%(id)s.mp3',
	'noplaylist' : True,
	'nooverwrites': True,
}
with youtube_dl.YoutubeDL(options) as ydl:
	video_id = ydl.extract_info(url, download=False).get("id", None)
	video_file = "yt_audio/{}.mp3".format(video_id)
	if not os.path.exists(video_file):
		ydl.download([url])

fadeduration = 0.25
fadefilter = "afade=t=in:ss=0:d={0},afade=t=out:st={1}:d={0}".format(fadeduration, duration - fadeduration)

print("converting/cropping")
runcommand(["ffmpeg", "-ss", str(start), "-t", str(duration), "-y", "-i", video_file, "-af", fadefilter, outfile ])

print("playing...")
runcommand(["open", outfile])

webIO_implementation.py

from pywebio import start_server
from pywebio.input import input, FLOAT, TEXT, URL, TIME
from pywebio.output import put_text
import sys, re, subprocess, youtube_dl, os
import time


def Download(url, outfile, start=None, duration=None):
    options = {
        'format': 'bestaudio/best',
        'extractaudio': True,
        'audioformat': "mp3",
        'outtmpl': 'yt_audio/%(id)s.mp3',
        'noplaylist': True,
        'nooverwrites': True,
    }
    with youtube_dl.YoutubeDL(options) as ydl:
        video_id = ydl.extract_info(url, download=False).get("id", None)
        video_file = "yt_audio/{}.mp3".format(video_id)
        if not os.path.exists(video_file):
            ydl.download([url])

    fade_duration = .5
    fade_filter = "afade=t=in:ss=0:d={0},afade=t=out:st={1}:d={0}".format(fade_duration, duration - fade_duration)

    if start and duration:
        runcommand(
            ["ffmpeg", "-ss", str(start), "-t", str(duration), "-y", "-i", video_file, "-af", fade_filter, "-b:a",
             "256k", outfile])
    else:
        runcommand(["ffmpeg", "-y", "-i", video_file, "-af", fade_filter, "-b:a", "256k", outfile])


def runcommand(command_array):
    return subprocess.check_output(command_array, stderr=subprocess.STDOUT).decode("utf-8")


def get_time(timestr):
    parts = timestr.split(":")
    if len(parts) == 2:
        return (int(parts[0]) * 60) + float(parts[1])
    if len(parts) == 1:
        return float(parts[0])
    raise ValueError("Only minutes:seconds supported")


def main():
    # height = input("Your Height(cm)：", type=FLOAT)
    # weight = input("Your Weight(kg)：", type=FLOAT)
    yt_url = input("Enter Youtube URL: ", type=URL, required=True)
    mp3_file = input("Enter Name of File: ", type=TEXT, required=True)
    start_time = input("Start Time: ", type=TEXT, required=False, placeholder='0:00', )
    end_time = input("End Time: ", type=TEXT, required=False, placeholder='3:30')

    if start_time and end_time:
        start_time = get_time(start_time)
        duration = get_time(end_time) - start_time
        Download(url=yt_url, outfile=mp3_file, start=start_time, duration=duration)
        put_text('File Cut to Time')
    else:
        Download(url=yt_url, outfile=mp3_file)
        put_text('Full File Availiable For Listening')


if __name__ == '__main__':
    main()
    # start_server(main, debug=True, port=8080)