YouTube Downloader with Separate Progress Bars

A Python 3 GUI application to download YouTube videos and/or audio with separate progress bars for audio, video, and processing tasks. Built using Tkinter and pytubefix, with FFmpeg support for merging audio and video streams.

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Features

• Download audio-only, video-only, or both (merged).
• Supports progressive and adaptive streams up to 4K resolution.
• Separate progress bars for:
  • Audio download
  • Video download
  • Processing (converting or merging)
• Fetch available resolutions dynamically from the video URL.
• User-friendly GUI with Tkinter.
• Cross-platform: Works on Windows, macOS, and Linux.
• Automatically sanitizes filenames to avoid illegal characters.
• Option to open the containing folder after download completes.

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Libraries Used

Library	Purpose	Notes / Features
pytubefix	Handles YouTube video fetching and downloading, including adaptive streams	A fork of pytube that fixes current YouTube API issues
Tkinter	GUI framework for Python	Provides windows, buttons, entries, labels, progress bars
ttk	Styled Tkinter widgets (Progressbar, Combobox)	Used for better GUI appearance
subprocess	Runs FFmpeg commands for audio/video conversion and merging	Required to merge video + audio and convert formats
queue	Thread-safe communication between worker threads and UI thread	Ensures safe updates to Tkinter widgets from background threads
threading	Handles download tasks in background threads	Prevents GUI from freezing during downloads
os / sys	File path handling, OS-specific folder opening	Required for cross-platform file handling

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How It Works

1. URL Input: User enters a YouTube URL.
2. Fetch Resolutions: Clicking "Fetch Resolutions" queries available video resolutions.
3. Select Options: User can choose:
   • Resolution (e.g., 1080p, 720p)
   • Video format (mp4, webm)
   • Audio format (m4a, mp3, webm)
   • Download type (video, audio, or both)
4. Download Process:
   • Audio-only: Downloads the highest bitrate audio stream, converts it with FFmpeg.
   • Video-only: Downloads the selected resolution video stream.
   • Both: Downloads audio + video separately, then merges using FFmpeg.
5. Progress Bars:
   • Audio bar tracks audio download.
   • Video bar tracks video download.
   • Processing bar shows FFmpeg conversion/merge progress.
6. Completion:
   • Displays a message with file path.
   • Option to open the containing folder.

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Detailed Concepts

1. Tkinter GUI Programming

Tkinter is the standard GUI library for Python. Key components used in this project:

• Widgets: Basic GUI elements like Label, Entry, Button, Progressbar, and Combobox.
• Grid Layout: Positions widgets in a table-like grid using row and column. Example:

Label(root, text="YouTube URL:").grid(row=0, column=0, sticky=E)
Entry(root, textvariable=url_var).grid(row=0, column=1, columnspan=3, sticky=W)

• StringVar / DoubleVar: Special Tkinter variables that automatically update widgets when their value changes. Examples:

  • StringVar for text (URL, status, selected resolution)
  • DoubleVar for numeric values (progress bars)

progress_var = DoubleVar(value=0.0)
Progressbar(root, variable=progress_var, maximum=100)
progress_var.set(50.0)  # Updates bar visually

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2. Threading & Queues for Background Tasks

Downloading video/audio can block the GUI. To prevent freezing:

• Threading: Run download tasks in a separate background thread.
• Queue: Safe communication channel from the background thread to the main GUI thread.

ui_queue = queue.Queue()
threading.Thread(target=download_worker, args=(url,), daemon=True).start()

• Worker thread puts messages in the queue (ui_queue.put(...)).
• GUI polls the queue periodically (root.after(100, _process_ui_queue)), updating progress bars and status safely.

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3. Subprocess Module for Running External Commands (FFmpeg)

Subprocess allows executing system commands from Python:

• Used for audio conversion and merging audio/video.
• Example of converting audio:

ffmpeg_cmd = ["ffmpeg", "-y", "-i", "temp_audio.m4a", "final_audio.mp3"]
subprocess.run(ffmpeg_cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)

• Example of merging audio + video:

ffmpeg_cmd = [
    "ffmpeg", "-y",
    "-i", "video.mp4",
    "-i", "audio.m4a",
    "-c:v", "copy", "-c:a", "aac",
    "output.mp4"
]

• stdout and stderr are captured to prevent cluttering the console.

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4. YouTube Streaming Concepts

YouTube videos are available in different stream types:

• Progressive Streams: Contain both video and audio in one file. Easier to download but often limited in resolution.
• Adaptive Streams: Separate audio-only and video-only streams. Allows high-resolution video (4K+) but requires merging using FFmpeg.

Example using pytubefix:

yt.streams.filter(progressive=True, file_extension="mp4")  # video+audio
yt.streams.filter(only_video=True, file_extension="mp4")    # video only
yt.streams.filter(only_audio=True).order_by("abr").desc()   # audio only

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5. File Handling and OS Paths

• Cross-platform paths: Use os.path.join() instead of hardcoding slashes.
• Sanitize filenames to avoid illegal characters:

def sanitize_filename(name):
    return "".join(c if c.isalnum() or c in " ._-()" else "_" for c in name).strip()

• Open folder after download depending on OS:

if sys.platform == "win32": os.startfile(folder)
elif sys.platform == "darwin": subprocess.Popen(["open", folder])
else: subprocess.Popen(["xdg-open", folder])

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6. FFmpeg Basics

FFmpeg is a command-line tool for audio/video processing:

1. Merging audio + video:

ffmpeg -i video.mp4 -i audio.m4a -c:v copy -c:a aac output.mp4

2. Converting audio format:

ffmpeg -i temp_audio.m4a final_audio.mp3

3. Options Used in Code:

• -y: Overwrite output without asking
• -loglevel error: Only show errors
• -c:v copy: Copy video stream without re-encoding (fast)
• -c:a aac: Encode audio to AAC format for MP4 compatibility

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Installation

1. Clone the repo:

git clone https://github.com/fitandfine/youtube_downloader.git
cd youtube_downloader

2. Install dependencies:

pip install pytubefix

Tkinter is included with Python; install via OS package manager if missing.

3. Install FFmpeg:

• Ubuntu: sudo apt install ffmpeg
• Windows: Download FFmpeg and add to PATH see here: https://www.wikihow.com/Install-FFmpeg-on-Windows
• macOS: brew install ffmpeg

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Usage

python app.py

1. Enter YouTube URL.
2. Fetch resolutions.
3. Choose resolution, video/audio format, and download type.
4. Select save folder.
5. Start download.
6. Watch separate progress bars for audio, video, and processing.
7. Open folder when prompted.

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Author

Anup Chapain – Created with clarity, separate progress bars, and comments for maintainability.

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License

MIT License – free to use and modify.