Compiling libdatachannel

Prebuilt DLLs from OBS or pip lack VP8 support. We compile from source to get all codecs (H264, VP8, AV1, Opus).

Source

git clone --depth 1 --recurse-submodules https://github.com/paullouisageneau/libdatachannel.git
cd libdatachannel

Windows

Requirements: Visual Studio Build Tools 2019+ with C++ workload, cmake, ninja (available via conda).

call "C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Auxiliary\Build\vcvarsall.bat" x64
cmake -B build -G Ninja -DCMAKE_BUILD_TYPE=Release -DNO_WEBSOCKET=ON -DNO_EXAMPLES=ON -DNO_TESTS=ON -DUSE_NICE=OFF
cmake --build build --config Release

Output: build/datachannel.dll

Rename to: windows-x64-openssl-h264-vp8-av1-opus-datachannel-<version>.dll

Place in: bin/

Linux

Requirements: gcc/g++, cmake, ninja-build, libssl-dev.

sudo apt install build-essential cmake ninja-build libssl-dev
cmake -B build -G Ninja -DCMAKE_BUILD_TYPE=Release -DNO_WEBSOCKET=ON -DNO_EXAMPLES=ON -DNO_TESTS=ON -DUSE_NICE=OFF
cmake --build build --config Release

Output: build/libdatachannel.so

Rename to: linux-x64-openssl-h264-vp8-av1-opus-libdatachannel-<version>.so

Install to: /usr/local/lib/ or project bin/

If installed to a custom path, run sudo ldconfig or set LD_LIBRARY_PATH.

macOS

Requirements: Xcode Command Line Tools, cmake, ninja.

xcode-select --install
brew install cmake ninja
cmake -B build -G Ninja -DCMAKE_BUILD_TYPE=Release -DNO_WEBSOCKET=ON -DNO_EXAMPLES=ON -DNO_TESTS=ON -DUSE_NICE=OFF
cmake --build build --config Release

For universal binary (arm64 + x86_64):

cmake -B build -G Ninja -DCMAKE_BUILD_TYPE=Release -DNO_WEBSOCKET=ON -DNO_EXAMPLES=ON -DNO_TESTS=ON -DUSE_NICE=OFF -DCMAKE_OSX_ARCHITECTURES="arm64;x86_64"
cmake --build build --config Release

Output: build/libdatachannel.dylib

Rename to: macos-universal-openssl-h264-vp8-av1-opus-libdatachannel-<version>.dylib

Install to: /usr/local/lib/ or project bin/

Naming convention

<os>-<arch>-<tls>-<codecs>-datachannel-<version>.<ext>

os: windows, linux, macos
arch: x64, arm64, universal
tls: openssl (default), gnutls, mbedtls
codecs: supported packetizers, e.g. h264-vp8-av1-opus
version: libdatachannel version, e.g. 0.24.1

Verifying the build

import ctypes
lib = ctypes.CDLL('path/to/datachannel.dll')
for fn in ['rtcSetH264Packetizer', 'rtcSetVP8Packetizer', 'rtcSetAV1Packetizer', 'rtcSetOpusPacketizer']:
    try:
        getattr(lib, fn)
        print(f'{fn}: OK')
    except AttributeError:
        print(f'{fn}: MISSING')

CMake flags reference

Flag	Default	Purpose
`NO_WEBSOCKET`	OFF	Disable WebSocket support (not needed)
`NO_MEDIA`	OFF	Disable media transport (must be OFF for codecs)
`NO_EXAMPLES`	OFF	Skip building examples
`NO_TESTS`	OFF	Skip building tests
`USE_NICE`	OFF	Use libnice instead of libjuice for ICE
`USE_GNUTLS`	OFF	Use GnuTLS instead of OpenSSL
`USE_MBEDTLS`	OFF	Use Mbed TLS instead of OpenSSL

Runtime dependencies

libopus: Required for audio encoding. Install via conda install -c conda-forge libopus (Windows) or apt install libopus-dev (Linux) or brew install opus (macOS).
OpenSSL: Usually bundled or system-provided. On Windows, conda provides it.

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