yt-dlp is a feature-rich command-line video/audio downloader, forked from youtube-dl. It extracts media URLs from over a thousand websites using site-specific extractors, downloads via HTTP, HLS, DASH, RTMP, and other protocols, and supports extensive post-processing (FFmpeg transcoding, metadata embedding, chapter manipulation, etc.). The architecture is modular: a core engine (YoutubeDL) orchestrates extractors, downloaders, and postprocessors, all of which can be extended via a plugin system. Networking is abstracted behind a handler interface with support for requests, curl-cffi, and websockets. The codebase is well-structured, with clear patterns for authentication, geo-restriction handling, and format selection. It includes a sophisticated JavaScript challenge solver and Proof-of-Origin token system for YouTube. Despite its size, the project maintains good code organization and extensive test coverage.
NewPipe Extractor is a Java library that provides a unified abstraction for extracting structured metadata (streams, channels, playlists, comments, search results) from multiple streaming platforms including YouTube, SoundCloud, Bandcamp, PeerTube, and media.ccc.de. It reverse-engineers private APIs and scrapes HTML/JSON to produce normalized data models. The library is designed as a headless component for the NewPipe Android app but can be used independently. Its architecture features a service registry, abstract extractor classes, link handler factories for URL normalization, and a collector pattern for batch extraction with error accumulation. The codebase is well-tested with JUnit 5 and a mock/recording downloader system, but YouTube-specific extraction is fragile due to reliance on hardcoded client versions, JavaScript deobfuscation, and frequently changing InnerTube API schemas.