WebRTC Meetup Tokyo #20

1. C++ WebRTC
(DataChannel)
/ @llamerada_jp
WebRTC Meetup Tokyo #20

2. SE
/ /
GitHub : llamerada-jp
facebook : ito.yuuji
twitter : @llamerada_jp
blog : http://llamerad-jp.hatenablog.com/

3. /
PROCESSWARP
Web /

4. /
www.oinari.app
libvein
Server

5. /
libvein
Web /
2 PubSub
KVS
Seed / Server

6. Documents /
https://webrtc.org/native-code/development/
&
API code reading
WebRTC ( )
https://gist.github.com/szktty/
a47213f0077294c64ea58621c2dcfaf2
android iOS
CUI WebRTC
https://github.com/llamerada-jp/webrtc-cpp-sample
WebRTC
https://github.com/llamerada-jp/libwebrtc

7. Native APIs

8. WebRTC Native APIs ?
WebView / Electron
WebSocket
iOS / Android (C++ )
WebRTC Native APIs
API
API

9. WebRTC API ( )
connect
SDP
ICE
send data
disconnect
event
change status
recv data
raise error

10. libuv
libuv
main Thread
rtc::Runnable Thread
webrtc::
CreatePeerConnectionFactory
rtc::Runnable::Run
uv_loop
uv_async_send Event!

11. libvein
JavaScritp
WebAssembly
WebRTC/WebSocket API
SDP / ICE (Server /
Seed )
libvein core (C++)
WebSocket
Wrapper
WebRTC
Wrapper
Native
WebRTC
Browser
WebRTC
Browser
WebSocket
WebSocket++
C++
API
C
API
Python JavaScript

12. https://webrtc.org/native-code/development/
http://commondatastorage.googleapis.com/chrome-infra-docs/flat/depot_tools/
docs/html/depot_tools_tutorial.html

13. $ cd <workdir>
$ git clone https://chromium.googlesource.com/chromium/tools/depot_tools.git
$ export PATH=$PATH:`pwd`/depot_tools
$ cd <workdir>
$ mkdir webrtc-checkout
$ cd webrtc-checkout
$ fetch --nohooks webrtc
$ gclient sync
$ gn gen out/Default --args=‘is_debug=false’
$ ninja -C out/Default

14. Chrome WebRTC

15. @ WebRTC
Σ( ω )

16. chromium URL
https://omahaproxy.appspot.com/all
OS stable
branch_commit
HASH of chromium

17. $ cd <workdir>
$ git clone https://chromium.googlesource.com/chromium/src chromium
$ cd chromium
$ git show <HASH of chromium>:DEPS
< >
‘src/third_party/webrtc':
Var('webrtc_git') + '/src.git' + '@' + ‘784fccbd71c0130b32345d81459b5d0cb07ff6e5',
< >
HASH of webrtc

18. < gclient sync >
$ git fetch
$ git checkout <HASH of webrtc>
$ gclient sync
$ gn gen out/Default [--args='is_debug=false']
$ ninja -C out/Default [<target>]

19. @ Linux
static library(.a ) .o
.a
ar 1 .a
src/out/Default/obj/examples/peerconnection_client.ninja
build <target>: link <obj1> <obj2> …
build ./peerconnection_client: link obj/examples/
peerconnection_client/conductor.o obj/examples/
peerconnection_client/defaults.o obj/examples/
peerconnection_client/peer_connection_client.o obj/
examples/peerconnection_client/main.o obj/examples/
peerconnection_client/main_wnd.o obj/api/video/
video_frame_i420/i420_buffer.o obj/rtc_base/checks/
checks.o obj/rtc_base/stringutils/string_to_number.o

20. @ macOS
obj/sdk/mac_framework_objc_shared_library/WebRTC
obj/api/video_codecs/libbuiltin_video_encoder_factory.a
obj/api/video_codecs/libbuiltin_video_decoder_factory.a
src/out/Default/obj/sdk/mac_framework_objc_shared_library.ninja
src/obj/api/video_codecs/libbuiltin_video_encoder_factory.a
src/obj/api/video_codecs/libbuiltin_video_decoder_factory.a

21. nm
https://github.com/llamerada-jp/search-
symbol
chromium

22. peerconnection_client
https://github.com/llamerada-jp/webrtc-cpp-sample
API JavaScript JavaScript
C++ API

23. PeerConnectionObserver
class PCO : public webrtc::PeerConnectionObserver {
void OnSignalingChange(webrtc::PeerConnectionInterface::SignalingState new_state) override;
void OnAddStream(rtc::scoped_refptr<webrtc::MediaStreamInterface> stream) override;
void OnRemoveStream(rtc::scoped_refptr<webrtc::MediaStreamInterface> stream) override;
// DataChannel !
void OnDataChannel(rtc::scoped_refptr<webrtc::DataChannelInterface> data_channel) override;
void OnRenegotiationNeeded() override;
void OnIceConnectionChange(webrtc::PeerConnectionInterface::IceConnectionState new_state) override;
void OnIceGatheringChange(webrtc::PeerConnectionInterface::IceGatheringState new_state) override;
// ICE
void OnIceCandidate(const webrtc::IceCandidateInterface* candidate) override;
};

24. DataChannelObserver
class DCO : public webrtc::DataChannelObserver {
//
void OnStateChange() override;
//
void OnMessage(const webrtc::DataBuffer& buffer) override;
void OnBufferedAmountChange(uint64_t previous_amount) override;
};

25. SessionDescriptionObserver
class CSDO : public webrtc::CreateSessionDescriptionObserver {
void OnSuccess(webrtc::SessionDescriptionInterface* desc) override;
void OnFailure(const std::string& error) override;
};
class SSDO : public webrtc::SetSessionDescriptionObserver {
void OnSuccess() override;
void OnFailure(const std::string& error) override;
};
rtc::scoped_refptr<CSDO> csdo (new rtc::RefCountedObject<CSDO>());
rtc::scoped_refptr<SSDO> ssdo (new rtc::RefCountedObject<SSDO>());

26. &
CreatePeerConnectionFactory
class CustomRunnable : public rtc::Runnable {
public:
void Run(rtc::Thread* subthread) override {
peer_connection_factory = webrtc::CreatePeerConnectionFactory(
nullptr /* network_thread */, nullptr /* worker_thread */,
nullptr /* signaling_thread */, nullptr /* default_adm */,
webrtc::CreateBuiltinAudioEncoderFactory(),
webrtc::CreateBuiltinAudioDecoderFactory(),
webrtc::CreateBuiltinVideoEncoderFactory(),
webrtc::CreateBuiltinVideoDecoderFactory(),
nullptr /* audio_mixer */, nullptr /* audio_processing */);
if (peer_connection_factory.get() == nullptr) {
// Error
}
subthread->Run();
}
};

27. rtc::PhysicalSocketServer socket_server;
thread.reset(new rtc::Thread(&socket_server));
rtc::InitializeSSL();
CustomRunnable runnable;
thread->Start(&runnable);
< peer_connection_factory >
peer_connection = peer_connection_factory->CreatePeerConnection(configuration, nullptr, nullptr, &pco);
webrtc::DataChannelInit config;
// DataChannel
data_channel = peer_connection->CreateDataChannel("data_channel", &config);
data_channel->RegisterObserver(&dco);
peer_connection->CreateOffer(csdo, webrtc::PeerConnectionInterface::RTCOfferAnswerOptions());

28. std::string message(“hello!!”,);
webrtc::DataBuffer buffer(
rtc::CopyOnWriteBuffer(
message.c_str(),
message.size()),
true);
data_channel->Send(buffer);

29. class DCO : public webrtc::DataChannelObserver {
//
void OnMessage(const webrtc::DataBuffer& buffer) override {
std::cout << std::string(buffer.data.data<char>(), buffer.data.size()) << std::endl;
}
};

30. // Close
peer_connection->Close();
peer_connection = nullptr;
data_channel = nullptr;
peer_connection_factory = nullptr;
thread->Quit();
thread.reset();
rtc::CleanupSSL();

31. macOS : WEBRTC_MAC=1 WEBRTC_POSIX=1
Linux : WEBRTC_LINUX=1 WEBRTC_POSIX=1
clang (libc++ )
-stdlib=libc++
C++ RTTI -fno-rtti
typeinfo dynamic_cast
--start-group --end-group

32. $ clang++ -I<workdir/webrtc-checkout/src> -I<workdir/webrtc-checkout/src/
third_party/abseil-cpp> -DWEBRTC_MAC=1 -DWEBRTC_POSIX=1 -std=c++11 -W -Wall -
Wno-unused-parameter -O0 -g -fno-rtti -o <output> -o <source>
(github ) build
./build.sh
$ cd <path to build>
$ make clean
$ make VERBOSE=1

33. OpenSSL BoringSSL API
HTTP WebSocket
BoringSSL
WebRTC Third party src/third_party

34. WebRTC BSD
src/third_party
OSS WebRTC

35. WebRTC C++