fegger
b5e8d7174c
Add the sc_network library: RFC 3550 RtpHeader/RtpPacket serialize and parse (the receiver tolerates CSRC lists, extension headers, and padding by skipping/stripping them) and RFC 6184 H.264 payloading via H264Packetizer/H264Depacketizer. The packetizer splits Annex-B frames into NAL units (3- and 4-byte start codes), emitting single-NAL packets or FU-A fragments within the configured MTU, with the marker bit closing each frame and randomized SSRC/sequence by default. The depacketizer reassembles access units with 3-byte start codes, so both start-code widths round-trip byte-exactly; frames damaged by sequence gaps or missing fragments are dropped until the Phase 7 loss-recovery work. test_rtp covers header and packet round-trips, malformed-input rejections, splitter behavior, FU-A chunk bounds, full packetize -> depacketize round-trip, gap dropping, marker-only frame separation, sequence wrap, and empty inputs. meson test 3/3, valgrind clean.
3.2 KiB
Development Phases
This file breaks the project into incremental milestones. Each phase produces a working, testable slice of functionality. Do not start a phase until the previous one is validated.
Phase 1 — Project Skeleton
Goal: configure, compile, and run tests with no real dependencies.
- Meson build files (
meson.build,meson_options.txt). - Public module headers with
namespace sc. - Unit test that exercises a trivial utility function.
README.mdwith build instructions.
Validation: meson setup build && meson compile -C build && meson test -C build.
Phase 2 — Software H.264 Encode / Decode
Goal: encode raw pixel buffers to H.264 and decode them back, purely with FFmpeg software paths.
- Add
libavcodec,libavutil,libswscaledependencies. - Implement
EncoderFactory::create()andEncoder::encode(). - Implement
DecoderFactory::create()andDecoder::decode(). - Round-trip test: synthetic RGB frames → H.264 → decoded RGB.
Validation: unit test produces visually/structurally correct round-trip frames.
Phase 3 — PipeWire Screen Capture
Goal: capture the desktop and feed frames into the encoder.
- Add
libpipewire-0.3dependency. - Implement
CaptureFactory::create()using the xdg-desktop-portal. - Wire
CaptureSession::next_frame()→Encoder::encode()in a local smoke test that just writes a few encoded frames to disk.
Validation: manual run on a real Linux desktop session produces a valid H.264 bitstream.
Phase 4 — RTP Framing
Goal: packetize NAL units into RTP and depacketize them.
- Implement
RtpHeaderandRtpPacketserialize/parse. - Add H.264 NAL splitting and FU-A fragmentation.
- Unit test for serialization, fragmentation, and reassembly.
Validation: unit tests cover single-NAL and fragmented packet paths.
Phase 5 — Local UDP Sender → Receiver Loopback
Goal: send RTP packets over UDP and render the result locally.
- Implement
RtpTransportwith ASIO or raw UDP sockets. - Wire sender pipeline: capture → encode → RTP → localhost UDP.
- Wire receiver pipeline: localhost UDP → RTP → decode → renderer.
- Add SDL2/3 dependency and a minimal
Renderer.
Validation: screencast --send and screencast --receive on the same
machine show the captured desktop in a window.
Phase 6 — LAN Signaling and Discovery
Goal: two peers on the same LAN can find each other and negotiate a session.
- Implement mDNS/DNS-SD discovery with Avahi.
- Implement JSON WebSocket signaling.
- Extend CLI with
--peer-addressor--discover.
Validation: two machines on the same LAN connect without hard-coded IP addresses.
Phase 7 — Resilience and Polish
Goal: loss recovery, hardware acceleration, and packaging.
- NACK / PLI feedback loop.
- Jitter buffer on the receiver.
- VAAPI/NVENC hardware encode probes and fallback.
- Optional GUI target behind
meson -Dgui=true. .desktopfile, icon, packaging notes.
Validation: sustained streaming under packet loss; hardware accel smoke where available.
Current phase
Phase 5 — Local UDP Sender → Receiver Loopback.