ZeroCast — Cross-Platform Zero-Config LAN Screen Casting

Version 0.2.0 (workspace; see root Cargo.toml [workspace.package])

Website: yanchao1999.github.io/ZeroCast

Lightweight, zero-configuration LAN screen casting built around a shared Rust core and thin platform adapters.

Goals

• One shared core codebase
• Native performance, low latency, small binaries
• LAN-only: no cloud, no accounts
• Cross-platform: Windows, macOS, Linux, Android, iOS
• Edge receivers: Linux ARM boards (e.g. Raspberry Pi Zero W over Wi‑Fi)

Quick start

Build the workspace:

cargo build --workspace
cargo test --workspace
# FFmpeg roundtrip (426p + 720p IDR size); CI runs this automatically:
cargo test -p zerocast_transport --test ffmpeg_integration
# includes 10-frame cycle live-pipe roundtrip at 426p

Run the desktop app (requires ffmpeg on PATH for H.264 streaming):

Zero-config (mDNS, Phase 2a):

# Terminal 1 — receiver (publishes listen port + resolution via mDNS)
cargo run -p zerocast_desktop -- recv 0.0.0.0:5000 426 240 15

# Terminal 2 — sender (discovers receiver on the LAN)
cargo run -p zerocast_desktop -- stream 0.0.0.0:0 --discover

Profiles (low | med | high | auto) — same dimensions on both sides; auto uses your primary display (e.g. 1920×1080 @ 60):

# Pi Zero W–class / low bandwidth (426×240 @ 15 fps) — recommended for same-PC smoke tests
cargo run -p zerocast_desktop -- recv 0.0.0.0:5000 --profile low
cargo run -p zerocast_desktop -- stream 0.0.0.0:0 --discover --profile low

# 720p30
cargo run -p zerocast_desktop -- recv 0.0.0.0:5000 --profile med
cargo run -p zerocast_desktop -- stream 0.0.0.0:0 --discover --profile med

# Full display resolution (capped to 1080p, refresh up to 60 Hz)
cargo run -p zerocast_desktop -- recv 0.0.0.0:5000 --profile auto
cargo run -p zerocast_desktop -- stream 0.0.0.0:0 --discover --profile auto

With --discover and no --profile, the sender uses the receiver’s advertised width/height/fps from mDNS.

Manual IP (same machine or fixed address):

cargo run -p zerocast_desktop -- recv 0.0.0.0:5000 426 240 15
cargo run -p zerocast_desktop -- stream 0.0.0.0:0 127.0.0.1:5000 426 240 15

# Or pick a profile on the sender only (receiver window size is still from recv args)
cargo run -p zerocast_desktop -- stream 0.0.0.0:0 127.0.0.1:5000 --profile low

Install ffmpeg on your PATH. On Windows/macOS/Linux the app uses the primary display via scrap (falls back to a test pattern if capture is unavailable).

Run tests:

cargo test --workspace

Architecture (high level)

• Shared Rust Core + Thin Native Platform Adapters + Cross-Platform UI
• Media pipeline: Capture → GPU Texture → Hardware Encoder → RTP → HW Decode → GPU/HDMI (zero-copy target; MVP uses CPU RGB24 + minifb)
• Discovery: mDNS; Transport: RTP over UDP; Control: QUIC/TCP

Recommended stack (summary)

• Language: Rust
• UI: egui + wgpu
• Async runtime: tokio
• QUIC: quinn
• Device discovery: mdns-sd
• Audio: cpal + Opus (see docs/spec/std/zerocast-protocol-v1.md)
• Video codec: H.264 (start)

Project layout

• apps/desktop — desktop CLI (send, recv, cap, stream)
• crates/platform — cross-platform screen capture (scrap on desktop OSes)
• crates/transport — RTP/RTCP, H.264 encode (ffmpeg CLI), streaming loop
• crates/core — shared core (minimal today)
• crates/protocol — on-the-wire constants (spec)
• crates/audio — PCM capture + Opus encode/decode
• crates/discovery — mDNS-SD publish/browse (Phase 2a)

Docs for agents and maintainers

• Project site: yanchao1999.github.io/ZeroCast (source: docs/index.html)
• Protocol spec: docs/spec/std/zerocast-protocol-v1.md
• AI agent baseline: AGENTS.md
• Agent skill and instructions: SKILL.md
• Copilot contributor guidance: .github/copilot-instructions.md
• Recommended dependency snippets: DEPS.md
• ARM QEMU embedded recv lab: docs/QEMU-ARM-RECV.md

Roadmap (short)

1. Desktop MVP — screen capture, H.264 encode, RTP streaming, rendering ✅
2. Phase 2a — mDNS + same-PC discovery ✅ — docs/PHASE-2A.md
3. Phase 1b — encoder pipe + sender stats ✅ — docs/PHASE-1B.md
4. Phase 1c — discover negotiation ✅ — docs/PHASE-1C.md
5. Phase QoS v1 foundation — metrics hints, class=embedded (closed loop not done) — docs/PHASE-QOS.md
6. Phase Audio v0–v1.2 — Opus RTP, native codec, RTCP A/V sync ✅ — docs/PHASE-AUDIO.md, protocol v1.1
7. Phase QoS closed loop — hot reconfigure, RTCP/recv lag — docs/PHASE-QOS.md
8. Android receiver, then sender
9. iOS support (ReplayKit + VideoToolbox)
10. Embedded recv — Linux ARM (Pi Zero W, Wi‑Fi) — docs/PHASE-QOS.md