scrcpy is a high-performance desktop application that mirrors and controls Android devices over USB or TCP/IP. The client is a native C application using SDL3 for rendering and input, FFmpeg for media decoding, and libusb for USB-OTG mode. The server is a Java service running on the Android device that captures screen and audio via MediaCodec and hidden Android APIs, streaming them over an ADB tunnel. The system supports multiple input modes (SDK injection, UHID, AOA HID), video/audio recording, V4L2 loopback output, and clipboard synchronization. Architecture is client-server with a well-defined protocol, trait-based pipeline for frame/packet processing, and extensive cross-platform support (Linux, Windows, macOS).
Opencast is a mature, open-source lecture capture and video management platform designed for educational institutions. It provides a complete pipeline for recording, processing, managing, and distributing academic video content. The system is built as a modular Java application using OSGi (Karaf) for service composition, with a REST API and a GraphQL layer for modern client interactions. Core capabilities include scheduled capture from lecture hall devices, automated workflow-driven processing (transcoding, transcription, captioning, silence detection, video editing), versioned asset storage (with AWS S3 support), multi-channel distribution (YouTube, OAI-PMH, streaming servers), and a rich admin UI for metadata management, access control, and analytics. The architecture follows a microservices-like pattern with separate API, implementation, and remote proxy modules, enabling distributed deployment across worker, admin, and presentation nodes. External dependencies include Elasticsearch/OpenSearch for search indexing, a relational database (MySQL/MariaDB/PostgreSQL), FFmpeg for media inspection and processing, and various cloud services for transcription and publication. The codebase demonstrates strong engineering practices with consistent module structure, extensive test coverage, and a well-documented upgrade path spanning over a decade of development.