7 notes
How to capture Apple Pencil pressure, tilt, and azimuth on iOS and inject them as native tablet events on macOS using CGEvent's hidden tablet fields. Includes wire format, coordinate mapping, and App Store considerations.
Deep dive into Astropad's tile-based LIQUID protocol: GPU-accelerated tile diffing with Metal compute shaders, adaptive codec switching between tiles and H.264/HEVC, LZ4 compression, and the architecture that achieves 16ms end-to-end latency.
Eliminate all CPU pixel copies in a video streaming pipeline using IOSurface, Metal textures, and CVMetalTextureCache. The technique that turns 50ms latency into 5ms on Apple Silicon's unified memory architecture.
Build a multiplexed QUIC transport layer using Apple's Network.framework for remote desktop streaming. Covers reliable streams for control, unreliable datagrams for video, fragmentation, and latency measurement.
Configure VideoToolbox for ultra-low latency HEVC/H.264 encoding on Apple Silicon. Covers real-time settings, parameter set extraction, bitrate control, and keyframe management for remote desktop streaming.
How to build a high-performance screen capture pipeline using Apple's ScreenCaptureKit framework — the same API used by Astropad Workbench. Covers discovery, filtering, configuration, IOSurface zero-copy, and frame status handling.
A comprehensive reverse engineering analysis of Astropad Workbench (codename Stargate), revealing the internal architecture of the LIQUID protocol — a Rust-based tile rendering engine using QUIC transport, GPU-accelerated diffing, and adaptive H.264/HEVC encoding.