Add mDNS/DNS-SD discovery and JSON session negotiation so two peers on
a LAN connect without hard-coded addresses.
- Discovery (Avahi threaded-poll client): the receiver announces
_screencast._tcp with its signaling port; senders browse and resolve
peers. Strict lock ordering (poll lock before state mutex) keeps the
callbacks deadlock-free; name collisions rename via
avahi_alternative_service_name.
- Signaling: one JSON object per newline-terminated TCP line. The
receiver hosts a server (port 5005) and answers session offers with
its RTP port; senders connect, offer, and stream to the negotiated
endpoint. WebSocket was deferred: no WS library is installed, the
skill permits plain TCP, and the wire format is transport-agnostic.
- Dual-stack transports: this machine resolves its own services over
IPv6, so getaddrinfo now runs AF_UNSPEC and listeners bind IPv6 with
IPV6_V6ONLY=0 (IPv4 fallback), covering UDP and TCP alike. The
signaling client shutdown now uses shutdown() so a reader blocked in
recv() cannot hang the join (a plain close() does not wake it).
- CLI: --discover lists receivers (deduped to one entry per host);
--send auto-disovers when exactly one receiver is found; --peer
targets a receiver directly; --signaling-port overrides the default.
Validation: meson test 5/5 (new signaling round-trip test), valgrind
clean. End-to-end over loopback: --discover finds the announced
receiver, a probe negotiated a session and streamed 60 frames over
both IPv4 and IPv6, and the receiver reported stream started. mDNS
resolution was verified against avahi-browse as an independent
reference.
Wire the first end-to-end pipeline: capture -> encode -> packetize ->
UDP -> depacketize -> decode -> render.
- UdpRtpTransport: raw POSIX UDP sockets (IPv4 via getaddrinfo), a
receive jthread woken by socket close on stop; port 0 skips binding
so the sender uses an OS-assigned source port. ASIO stays deferred
to the signaling phase per ARCHITECTURE.md.
- SdlRenderer: SDL3 window/renderer with RGBA texture upload; the
texture is recreated on resolution change. RendererFactory now
returns RendererResult so SDL init failures carry a message,
mirroring the codec/capture error patterns.
- screencast binary: parse_cli plus SenderPipeline/ReceiverPipeline
per the app scaffolds; the sender creates its encoder once capture
reports real dimensions, the receiver keeps a bounded 3-frame queue
to hold latency down and renders on its own thread until the window
closes. cli argv signature fixed to 'const char* const*' so main's
argv converts implicitly.
- Encoder: drop AV_CODEC_FLAG_GLOBAL_HEADER so libx264 repeats SPS/PPS
in-band at each keyframe -- the receiver decodes from the bitstream
alone, which also makes mid-stream joins and later PLI recovery
work without out-of-band parameter negotiation. The round-trip test
now exercises exactly that path.
- tests: new udp-loopback integration test pushes synthetic frames
through a real localhost socket and decodes 10/10 frames with the
right dimensions; valgrind clean (loopback + codec). meson test 4/4.
Manual validation on the desktop (receiver window shows the captured
desktop) is documented in docs/RUNBOOK.md.
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.
Add FFmpeg-based encoder/decoder with SPS/PPS extradata, Annex-B output
normalization, low-latency libx264 settings, and a round-trip unit test.
Includes review hardening: cached SwsContext, bitrate-only rate control,
std::byte/uin8_t cast helpers, and richer test assertions.
fegger