winrtc/patches_for_WebRTC_org/master-08b11caf

Patching WebRTC for Windows

This document will walk you through the steps required for getting the WebRTC code base, patching it and building it for UWP. These patches are being contributed back. Some of these patches were already merged into their original repos, but didn't rolled over WebRTC yet.

Prerequisites

Machine requirements

• Windows 10 (build 18362) or later.
• At least 8GB of RAM (16GB of RAM is recommended).
• At least 15GB of disk space.
• SSD drive formatted with NTFS.

External applications

• Microsoft Visual Studio 2019 16.6.2.
• Command Prompt (Windows Terminal is recommended, but cmd.exe works as well).

In the Visual Studio Installer app, please verify if Visual Studio 2019 has the Desktop development with C++ and Universal Windows Platform development workloads installed. Switch to the Individual components tab. Make sure C++ MFC for latest v142 build tools (x86 & x64) and C++ ATL for latest v142 build tools (x86 & x64) are selected.

If you want to build for ARM/ARM64, also select the C++ MFC and ATL v142 build tools and C++ Universal Windows Platform support for v142 build tools for the corresponding architecture.

When installed by Visual Studio, the Windows SDK doesn't have the SDK Debugging Tools installed. Please go to Control Panel → Programs → Programs and Features → Select the most recent Windows Software Development Kit → Change → Change → Select Debugging Tools For Windows → Change.

Acquiring WebRTC code base

Open the Windows Terminal and type the following commands:

Getting depot_tools

WebRTC uses Chromium's build tools named depot_tools. depot_tools is constantly updated and we're going to grab the right one for the m80 branch. Let's start by cloning the depot_tools repo in the root of the c: drive.

c:
cd \
git clone https://chromium.googlesource.com/chromium/tools/depot_tools

Let's switch to the m80 branch of depot_tools and bring the most recent bits for this branch to your machine.

cd depot_tools
git checkout chrome/3987
git fetch

depot_tools has some tools that are not part of the repo and need to be downloaded. Let's download these extra tools. This might take a few minutes.

gclient

At this moment, gclient will offer you to use the most recent version of depot_tools. We do not want that.

Your depot_tools checkout is configured to fetch from an obsolete URL
Would you like to update it? [y/N]: N

Setting up the environment

Set the path environment variable to execute commands in the depot_tools folder.

set PATH=c:\depot_tools;%PATH%

Keep in mind that the previous command gave priority to programs sitting in that folder. One of the programs sitting in the depot_tools folder is a batch file named git. It means that for the duration of this terminal session, when you execute git you're calling Google's git, not the one was previously installed in your dev box.

Make sure that any python program executed in this session comes from the depot_tools.

where python

The response should be c:\depot_tools\python.bat.

Now that we're using the right python version from depot_tool, let's install pip and pywin.

Let's first install pip.

python -m pip install --upgrade pip
cd c:\depot_tools\
pip install pywin32

After that, install pywin.

cd S:\depot_tools\bootstrap-3_8_0b1_chromium_1_bin\python\bin\Scripts
pip install pywin32

Don't worry about the deprecation notice from Python 2.7. Migrating to Python3 is a working in progress that didn't make it to the m80 branch.

Let's inform depot_tools that we don't have access to Google's internal tools.

set DEPOT_TOOLS_WIN_TOOLCHAIN=0

The GYP build tool must be informed about the version of the Visual Studio we're using.

set GYP_MSVS_VERSION=2019

Create the folder where the code base will be placed.

c:
mkdir c:\webrtc
cd c:\webrtc

Downloading the bits

Tell to the gclient tool to initialize your local copy of the repos.

gclient

Request the tools to fetch the WebRTC code base. The following command will take time. Past experience shows that it might take around 1 hour an 10 minutes.

fetch --nohooks --no-history webrtc

Change to the branch-heads/3987 branch. This is the commit that the UWP patches (see below) are based on. You can use a different commit but the patches might not apply correctly.

cd src
git checkout branch-heads/3987

Instruct the tools to bring the bits from all the sub repositories to your dev box. This will take awhile.

gclient sync

Applying the patches

As is, WebRTC doesn't build for modern Windows (UWP). Probably you already know that and it is why you're reading this. So, now is time to patch WebRTC for building for UWP.

There is a batch file named patchWebRTC.cmd in the folder patches_for_WebRTC_org/master--08b11caf of the WinRTC repo for patching WebRTC. The patchWebRTC.cmd batch file needs to know where is the WebRTC code base to be patched. The environment variable WEBRTC_MASTER_ROOT should contain the path for the WebRTC code base you've just downloaded.

set WEBRTC_MASTER_ROOT=c:\webrtc\src

Now, you just need to run the batch file that will patch all the necessary repos the form the WebRTC code base.

patchWebRTC.cmd

Setting up the and building

Setting up

WebRTC is a extensive project and not all of its modules are required for producing an UWP app with real time communications capabilities. Because of that, some parts of the WebRTC code base that do not build for UWP were not patched by the patchWebRTC.cmd script. You don't need to worry, the following ninja command excludes the unnecessary modules and prepares to build the drop for UWP.

gn --ide=vs2019 gen out\msvc\x64\Release --filters=//:webrtc "--args=is_debug=false use_lld=false is_clang=false rtc_include_tests=false rtc_build_tools=false rtc_win_video_capture_winrt=true target_os=\"winuwp\" rtc_build_examples=false"

This will set up the out\msvc\x64\Release folder for building WebRTC for the UWP x64 Release configuration. Build settings can be customized. To view the full list of editable build arguments, you can run

gn args --list out\msvc\x64\Release

Please note that not all settings are supported in a UWP build.

Building

One you have the project set up, you can choose between building it inside Visual Studio or directly with the command line.

With Visual Studio 2019

Assuming that your terminal has Visual Studio in the path, you can open the generated solution file by running the following command.

devenv out\msvc\x64\Release\all.sln

To build on Visual Studio, make sure you can see the Solution Explorer window (View → Solution Explorer), then right-click on the webrtc project (it should be on the bottom of the window), and then click on Select as Startup Project. Now is just build the solution with Build → Build Solution.

With command line

Run the following command to build the patched WebRTC from the command line.

ninja -C out\msvc\x64\Release

Consuming the generated binaries

You'll need to set 5 pieces of configuration on your application for consuming this patched version of WebRTC. You'll find these information in the webrtc.ninja file inside the out\msvc\x64\Release\obj folder.

The following instructions should work for Release builds on x64. For Debug builds and x86 builds you should harvest similar information from the webrtc.ninja file placed on its respective obj directory.

1. Add include folders

Click on the project name, then go to project properties (Alt-F7). Click on Configuration Properties → C/C++ → General → Additional Include Directories and add the following paths:

c:\webrtc\src
c:\webrtc\src\out\msvc\$(PlatformTarget)\$(Configuration)\gen
c:\webrtc\src\third_party\abseil-cpp
c:\webrtc\src\third_party\libyuv\include
c:\webrtc\src\third_party\protobuf\src
c:\webrtc\src\out\msvc\$(PlatformTarget)\$(Configuration)\gen\protoc_out
ration)\gen\protoc_out

Click on Apply, but don't close the project properties window.

2. Preprocessor macros:

Click on Preprocessor → Preprocessor Definitions and add the following definitions:

USE_AURA=1;_HAS_EXCEPTIONS=0;__STD_C;_CRT_RAND_S;_CRT_SECURE_NO_DEPRECATE;_SCL_SECURE_NO_DEPRECATE;_ATL_NO_OPENGL;_WINDOWS;CERT_CHAIN_PARA_HAS_EXTRA_FIELDS;PSAPI_VERSION=2;WIN32;_SECURE_ATL;_USING_V110_SDK71_;WINUWP;__WRL_NO_DEFAULT_LIB__;WINAPI_FAMILY=WINAPI_FAMILY_PC_APP;WIN10=_WIN32_WINNT_WIN10;WIN32_LEAN_AND_MEAN;NOMINMAX;_UNICODE;UNICODE;NTDDI_VERSION=NTDDI_WIN10_RS2;_WIN32_WINNT=0x0A00;WINVER=0x0A00;NVALGRIND;DYNAMIC_ANNOTATIONS_ENABLED=0;WEBRTC_ENABLE_PROTOBUF=1;WEBRTC_INCLUDE_INTERNAL_AUDIO_DEVICE;RTC_ENABLE_VP9;HAVE_SCTP;WEBRTC_LIBRARY_IMPL;WEBRTC_NON_STATIC_TRACE_EVENT_HANDLERS=0;WEBRTC_WIN;ABSL_ALLOCATOR_NOTHROW=1;GOOGLE_PROTOBUF_NO_RTTI;GOOGLE_PROTOBUF_NO_STATIC_INITIALIZER

Feel free to copy-and-paste with the semicolons in a single line. Visual Studio will expand them to multiple lines next time you open this UI.

Click on Apply, but don't close the project properties window.

3. Linker additional library path

Click on Linker → General → Additional Library Directories and add the following path:

c:\webrtc\src\out\msvc\$(PlatformTarget)\$(Configuration)\obj

Click on Apply, but don't close the project properties window.

4. WebRTC library name

Click on Input → Additional Dependencies and add the following file name:

webrtc.lib

5. Discarding libcmt from the linking

Still on the Input tab, click on Ignore Specific Default Libraries and add libcmt.

It should be libcmtd on debug builds.

Victory

Click on OK and you should be good to use WebRTC APIs on your UWP app! :)