YouTube Downloader with pytubefix

Simple Python CLI to download from YouTube. Uses pytubefix, a maintained fork of pytube. Option 3 now asks you which resolution to grab, then merges the best audio with it.

Features

• 1. Audio Only: downloads highest bitrate audio, saves as .m4a
• 2. Video Only: downloads highest resolution MP4 video, no audio
• 3. Best Quality with choice: lists all available MP4 resolutions, you pick one, then it downloads that video plus best audio and merges to a single MP4 with ffmpeg
• 4. Progressive: downloads classic YouTube MP4 with audio and video together, max 720p, no ffmpeg needed

Requirements

• Python 3.8 or newer
• pip install pytubefix
• ffmpeg in PATH (required only for option 3)

Installation

pip install pytubefix

Install ffmpeg:

• Windows: winget install ffmpeg
• macOS: brew install ffmpeg
• Linux: sudo apt install ffmpeg

Verify: ffmpeg -version

Usage

python yt_downloader.py

1. Paste YouTube URL
2. Choose 1 to 4
3. If you choose 3, you will see:

Available qualities:
1. 2160p (60fps, avc1)
2. 1440p (60fps, avc1)
3. 1080p (60fps, avc1)
4. 720p (30fps, avc1)
Choose 1-4 [Enter for best 2160p]:

Press Enter for the best, or type 2 for 1440p, etc.

Files go to ./downloads/

What each mode does

1. Audio Only

Selects only_audio streams, orders by abr, downloads first. Renames to .m4a. This is AAC audio, not MP3. To get MP3, run: ffmpeg -i file.m4a file.mp3

2. Video Only

Selects only_video MP4 streams, orders by resolution, downloads first. No audio track included.

3. Best Quality

• Builds a unique list of MP4 video-only resolutions
• Lets you pick
• Downloads best audio separately
• Checks for ffmpeg first. If missing, it stops and keeps the two files
• Merges with: ffmpeg -y -i video -i audio -c:v copy -c:a aac -movflags +faststart output.mp4
• Output name includes resolution: Video Title_1080p.mp4

4. Progressive

Selects progressive MP4 streams. These are pre-merged by YouTube and capped at 720p. If none exist, the script exits with a message.

Output examples

downloads/
  My Song.m4a
  video_only_My Video.mp4
  My Video_2160p.mp4
  My Video_1080p.mp4
  Old Video.mp4

Troubleshooting

• RegexMatchError or VideoUnavailable: YouTube changed. Update: pip install -U pytubefix
• ffmpeg not found: option 3 will not merge. Install ffmpeg and ensure it is in PATH
• No MP4 video-only streams: some videos are VP9 or AV1 only. Remove file_extension="mp4" in the filter to see them, then output to .mkv
• No progressive stream: common for 1080p and above. Use option 3
• Slow speeds: YouTube throttles. Try again later or use option 4

Quality notes

YouTube's true best is often VP9 in webm, not H.264 in MP4. This script filters for MP4 for phone compatibility. If you want 4K HDR VP9:

1. Change filter(only_video=True, file_extension="mp4") to filter(only_video=True)
2. Change output extension to .mkv
3. ffmpeg will copy both streams with no re-encode

Legal

Download only content you own or have permission to save. You are responsible for following YouTube Terms of Service and copyright law in Pakistan and your region.

Customizing

• Change folder: edit out_dir = "downloads"
• Auto-pick without prompt: set video = unique[resolutions[0]] and skip input
• Force 1080p max: filter by if int(s.resolution[:-1]) <= 1080