Repository layout

Repository layout

.github/
  workflows/                       the ten build pipelines
  actions/resolve-webrtc-branch/   shared branch resolution
    action.yml
    resolve_webrtc_branch.py
WebRtcInterop/                     the C ABI shim — see below
  include/Interop.h                the public ABI
  src/                             implementation
  test/                            C harnesses driving the built DLL
tools/make_platform_diagram.py     regenerates the wiki figure
wiki/                              source of these pages
README.md
LICENSE                            MIT

Everything here is live. Two dormant experiments — WebRtcNativeObjectsWrapper/, a CMake "Hello CMake" sketch, and Links.md, a bookmark dump behind it — were removed once WebRtcInterop/ became real; they are in the history if ever wanted.

.github/

The working content of the repository. Ten workflows, described in Workflow reference, plus one composite action holding the branch-resolution logic they all share (Branch selection).

The resolver is a real Python script rather than inline shell so that it can be run and tested outside CI:

python .github/actions/resolve-webrtc-branch/resolve_webrtc_branch.py --branch 7977

wiki/

These pages, kept in the repository so they are reviewed alongside the workflows they describe. The GitHub wiki is published from them; the repository README.md records the copy step.

WebRtcInterop/ — the C ABI shim

WebRTC's API is C++ and cannot be P/Invoked directly, so .NET needs a flat C surface in front of it. That is what this directory is, and it is the missing piece for a Windows binding that replaces SIPSorcery.

Built by WebRtcNativeInteropWindows, which is the only workflow here that compiles code from this repository rather than from Google's tree.

File	Contents
include/Interop.h	the public ABI — the only file a caller needs
src/Internal.h	handle definitions, shared between the translation units
src/Interop.cc	library lifecycle, factory, device enumeration, tracks
src/PeerConnection.cc	peer connection, observers, negotiation
src/DataChannel.cc	SCTP data channels
src/FrameSink.cc	video frame delivery
test/	C harnesses that load the built DLL and drive it
BUILD.gn	declares rtc_shared_library("WebRtcInterop") with its dependency list
.clang-format, format.sh, NOTICE	Chromium style, formatter, upstream notice

How it builds

BUILD.gn opens with import("../webrtc.gni") and depends on siblings such as ../api, ../pc and ../media, so it only resolves from inside a WebRTC checkout. The workflow therefore copies this directory to src/WebRtcInterop and appends "//WebRtcInterop" to the root group("default") deps so ninja reaches it. That graft is edit 6 on top of the standard shared-library patch.

That is not merely convenient. webrtc.dll is compiled with clang against libc++, and anything MSVC compiles has a different std::string, allocator and exception model — so the shim has to be built by the same toolchain, from inside the same tree.

The convention it follows

Interop ABI is the specification: the ownership rule, the threading rule, the string rules, and the verified struct layouts. Read it before adding a function; the conventions are not obvious from the header alone.

Everything the ABI page lists is implemented — the twenty-five functions of slice one, plus data channels — and each area has a test in test/ that drives it against the built DLL.

This work dates from 2023 and predates the current workflows. Its original standalone repository was folded in here; the full history is preserved on the archive/webrtcinterop-2023 branch.

Conventions

• Default branch is main.
• C/C++ is Chromium style via WebRtcInterop/.clang-format; format.sh applies it and needs dos2unix and clang-format on PATH.
• There is no test suite, linter or package manifest. Validation of a workflow change is reading it, then dispatching it.