Amazon Kinesis Video Streams C WebRTC SDK

Pure C WebRTC Client for Amazon Kinesis Video Streams

Key Features • Build • Run • Documentation • Setup IoT • Use Pre-generated Certificates • Related • License

Note

We have switched from using the 'master' branch to the 'main' branch. Please update your references accordingly.

New feature announcements

Please refer to the release notes in Releases page

Key Features

• Audio/Video Support
  • VP8
  • H264
  • Opus
  • G.711 PCM (A-law)
  • G.711 PCM (µ-law)
• Developer Controlled Media Pipeline
  • Raw Media for Input/Output
  • Callbacks for Congestion Control, FIR and PLI (set on RtcRtpTransceiver)
• DataChannels
• NACKs
• STUN/TURN Support
• IPv4/IPv6
• Signaling Client Included
  • KVS Provides STUN/TURN and Signaling Backend
  • Connect with Android/iOS/Web using pre-made samples
• Storage for WebRTC [NEW]
  • Ingest media into a Kinesis Video Stream.
• Portable
  • Tested on Linux/MacOS
  • Tested on x64, ARMv5
  • Build system designed for pleasant cross-compilation
• Small Install Size
  • Sub 200k library size
  • OpenSSL, libsrtp, libjsmn, libusrsctp and libwebsockets dependencies.

Build

Download

To download run the following command:

git clone --recursive https://github.com/awslabs/amazon-kinesis-video-streams-webrtc-sdk-c.git

You will also need to install pkg-config and CMake and a build environment

Configure

Create a build directory in the newly checked out repository, and execute CMake from it.

mkdir -p amazon-kinesis-video-streams-webrtc-sdk-c/build; cd amazon-kinesis-video-streams-webrtc-sdk-c/build; cmake ..

We have provided an example of using GStreamer to capture/encode video, and then send via this library. This is only build if pkg-config finds GStreamer is installed on your system.

On Ubuntu and Raspberry Pi OS you can get the libraries by running

$ sudo apt-get install libssl-dev libcurl4-openssl-dev liblog4cplus-dev libgstreamer1.0-dev libgstreamer-plugins-base1.0-dev gstreamer1.0-plugins-base-apps gstreamer1.0-plugins-bad gstreamer1.0-plugins-good gstreamer1.0-plugins-ugly gstreamer1.0-tools 

By default we download all the libraries from GitHub and build them locally, so should require nothing to be installed ahead of time. If you do wish to link to existing libraries you can use the following flags to customize your build.

Dependency requirements

These would be applicable if the SDK is being linked with system dependencies instead of building from source by the SDK. libmbedtls: >= 2.25.0 & < 3.x.x libopenssl: = 1.1.1x libsrtp2 : <= 2.5.0 libusrsctp : <= 0.9.5.0 libwebsockets : >= 4.2.0

Cross-Compilation

If you wish to cross-compile CC and CXX are respected when building the library and all its dependencies. You will also need to set BUILD_OPENSSL_PLATFORM, BUILD_LIBSRTP_HOST_PLATFORM and BUILD_LIBSRTP_DESTINATION_PLATFORM. See our codecov.io for an example of this. Every commit is cross compiled to ensure that it continues to work.

Static Builds

If -DBUILD_STATIC_LIBS=TRUE then all dependencies and KVS WebRTC libraries will be built as static libraries.

CMake Arguments

You can pass the following options to cmake ...

• -DBUILD_STATIC_LIBS -- Build all KVS WebRTC and third-party libraries as static libraries.
• -DADD_MUCLIBC -- Add -muclibc c flag
• -DBUILD_DEPENDENCIES -- Whether or not to build depending libraries from source
• -DBUILD_OPENSSL_PLATFORM -- If building OpenSSL what is the target platform
• -DBUILD_LIBSRTP_HOST_PLATFORM -- If building LibSRTP what is the current platform
• -DBUILD_LIBSRTP_DESTINATION_PLATFORM -- If building LibSRTP what is the destination platform
• -DBUILD_TEST=TRUE -- Build unit/integration tests, may be useful for confirm support for your device. ./tst/webrtc_client_test
• -DCODE_COVERAGE -- Enable coverage reporting
• -DCOMPILER_WARNINGS -- Enable all compiler warnings
• -DADDRESS_SANITIZER -- Build with AddressSanitizer
• -DMEMORY_SANITIZER -- Build with MemorySanitizer
• -DTHREAD_SANITIZER -- Build with ThreadSanitizer
• -DUNDEFINED_BEHAVIOR_SANITIZER -- Build with UndefinedBehaviorSanitizer
• -DLINK_PROFILER -- Link with gperftools (available profiler options are listed here)

To clean up the open-source and build folders from previous build, use cmake --build . --target clean from the build folder

For windows builds, you will have to include additional flags for libwebsockets CMake. Add the following flags to your cmake command, or edit the CMake file in ./CMake/Dependencies/libwebsockets-CMakeLists.txt with the following:

cmake .. -DLWS_HAVE_PTHREAD_H=1 -DLWS_EXT_PTHREAD_INCLUDE_DIR="C:\Program Files (x86)\pthreads\include" -DLWS_EXT_PTHREAD_LIBRARIES="C:\Program Files (x86)\pthreads\lib\x64\libpthreadGC2.a" -DLWS_WITH_MINIMAL_EXAMPLES=1

Be sure to edit the path to whatever pthread library you are using, and the proper path for your environment.

Build

To build the library and the provided samples run make in the build directory you executed CMake.

make

Building with dependencies off

In addition to the dependencies already installed, install the dependencies using the appropriate package manager.

On Ubuntu: sudo apt-get install libsrtp2-dev libusrsctp-dev libwebsockets-dev

On MacOS: brew install srtp libusrsctp libwebsockets

To use OpenSSL:

cmake .. -DBUILD_DEPENDENCIES=OFF -DUSE_OPENSSL=ON

To use MBedTLS:

cmake .. -DBUILD_DEPENDENCIES=OFF -DUSE_OPENSSL=OFF -DUSE_MBEDTLS=ON

Note: Please follow the dependency requirements to confirm the version requirements are satisfied to use the SDK with system installed dependencies. If the versions are not satisfied, this option would not work and enabling the SDK to build dependencies for you would be the best option to go ahead with.

Run

Setup your environment with your AWS account credentials and AWS region:

• First set the appropriate environment variables so you can connect to KVS. If you want to use IoT certificate instead, check Setup IoT.

export AWS_ACCESS_KEY_ID= <AWS account access key>
export AWS_SECRET_ACCESS_KEY= <AWS account secret key>

• Optionally, set AWS_SESSION_TOKEN if integrating with temporary token

export AWS_SESSION_TOKEN=<session token>

• Region is optional, if not being set, then us-west-2 will be used as default region.

export AWS_DEFAULT_REGION= <AWS region>

Setup logging:

Set up the desired log level. The log levels and corresponding values currently available are:

1. LOG_LEVEL_VERBOSE ---- 1
2. LOG_LEVEL_DEBUG ---- 2
3. LOG_LEVEL_INFO ---- 3
4. LOG_LEVEL_WARN ---- 4
5. LOG_LEVEL_ERROR ---- 5
6. LOG_LEVEL_FATAL ---- 6
7. LOG_LEVEL_SILENT ---- 7
8. LOG_LEVEL_PROFILE ---- 8

To set a log level, run the following command:

export AWS_KVS_LOG_LEVEL = <LOG_LEVEL>

For example:

export AWS_KVS_LOG_LEVEL = 2 switches on DEBUG level logs while runnning the samples

Note: The default log level is LOG_LEVEL_WARN.

Starting v1.8.0, by default, the SDK creates a log file that would have execution timing details of certain steps in connection establishment. It would be stored in the build directory as kvsFileLogFilter.x. In case you do not want to use defaults, you can modify certain parameters such as log file directory, log file size and file rotation index in the createFileLoggerWithLevelFiltering function in the samples. In addition to these logs, if you would like to have other level logs in a file as well, run:

export AWS_ENABLE_FILE_LOGGING=TRUE

Set path to SSL CA certificate (Optional)

If you have a custom CA certificate path to set, you can set it using:

export AWS_KVS_CACERT_PATH=../certs/cert.pem

By defaut, the SSL CA certificate is set to ../certs/cert.pem which points to the file in this repository:

Running the Samples

After executing make you will have sample applications in your build/samples directory. From the build/ directory, run any of the sample applications by passing to it the name of your signaling channel. If a signaling channel does not exist with the name you provide, the application creates one.

Sample: kvsWebrtcClientMaster

This application sends sample H264/Opus frames (path: /samples/h264SampleFrames and /samples/opusSampleFrames) via WebRTC. It also accepts incoming audio, if enabled in the browser. When checked in the browser, it prints the metadata of the received audio packets in your terminal. To run:

./samples/kvsWebrtcClientMaster <channelName>

To use the Storage for WebRTC feature, run the same command as above but with an additional command line arg to enable the feature.

./samples/kvsWebrtcClientMaster <channelName> 1

Sample: kvsWebrtcClientMasterGstSample

This application can send media from a GStreamer pipeline. The pipeline configuration is read from a .conf file. To run:

./samples/kvsWebrtcClientMasterGstSample <channelName> ./samples/configFiles/testAudioVideo.conf

Sample: kvsWebrtcClientViewer

This application accepts sample H264/Opus frames and prints them out. To run:

./samples/kvsWebrtcClientViewer <channelName>

Viewing Master Samples

After running one of the master samples, when the command line application prints "Signaling client connection to socket established", indicating that your signaling channel is created and the connected master is streaming media to it, you can view the stream. To do so, check the media playback viewer on the KVS Signaling Channels console or open the WebRTC SDK Test Page.

If using the WebRTC SDK Test Page, set the following values using the same AWS credentials and the same signaling channel that you specified for the master above:

• Access key ID
• Secret access key
• Signaling channel name
• Client ID (optional)

Then choose Start Viewer to start live video streaming of the sample H264/Opus frames.

Setup IoT

• To use IoT certificate to authenticate with KVS signaling, please refer to Controlling Access to Kinesis Video Streams Resources Using AWS IoT for provisioning details.
• A sample IAM policy for the IoT role looks like below, policy can be modified based on your permission requirement.

{
   "Version":"2012-10-17",
   "Statement":[
      {
          "Effect":"Allow",
          "Action":[
            "kinesisvideo:DescribeSignalingChannel",
            "kinesisvideo:CreateSignalingChannel",
            "kinesisvideo:GetSignalingChannelEndpoint",
            "kinesisvideo:GetIceServerConfig",
            "kinesisvideo:ConnectAsMaster"
          ],
          "Resource":"arn:aws:kinesisvideo:*:*:channel/${credentials-iot:ThingName}/*"
      }
   ]
}

Note: "kinesisvideo:CreateSignalingChannel" can be removed if you are running with existing KVS signaling channels. Viewer sample requires "kinesisvideo:ConnectAsViewer" permission. Integration test requires both "kinesisvideo:ConnectAsViewer" and "kinesisvideo:DeleteSignalingChannel" permission.

• With the IoT certificate, IoT credentials provider endpoint (Note: it is not the endpoint on IoT AWS Console!), public key and private key ready, you can replace the static credentials provider createStaticCredentialProvider() and freeStaticCredentialProvider() with IoT credentials provider like below, the credentials provider for samples is in createSampleConfiguration():

createLwsIotCredentialProvider(
            "coxxxxxxxx168.credentials.iot.us-west-2.amazonaws.com",  // IoT credentials endpoint
            "/Users/username/Downloads/iot-signaling/certificate.pem",  // path to iot certificate
            "/Users/username/Downloads/iot-signaling/private.pem.key", // path to iot private key
            "/Users/username/Downloads/iot-signaling/cacert.pem", // path to CA cert
            "KinesisVideoSignalingCameraIoTRoleAlias", // IoT role alias
            channelName, // iot thing name, recommended to be same as your channel name
            &pSampleConfiguration->pCredentialProvider));

freeIotCredentialProvider(&pSampleConfiguration->pCredentialProvider);

Use Pre-generated Certificates

The certificate generating function (createCertificateAndKey) in createDtlsSession() can take between 5 - 15 seconds in low performance embedded devices, it is called for every peer connection creation when KVS WebRTC receives an offer. To avoid this extra start-up latency, certificate can be pre-generated and passed in when offer comes.

Important Note: It is recommended to rotate the certificates often - preferably for every peer connection to avoid a compromised client weakening the security of the new connections.

Take kvsWebRTCClientMaster as sample, add RtcCertificate certificates[CERT_COUNT]; to SampleConfiguration in Samples.h. Then pass in the pre-generated certificate in initializePeerConnection() in Common.c.

configuration.certificates[0].pCertificate = pSampleConfiguration->certificates[0].pCertificate;
configuration.certificates[0].pPrivateKey = pSampleConfiguration->certificates[0].pPrivateKey;

where, `configuration` is of type `RtcConfiguration` in the function that calls `initializePeerConnection()`.

Doing this will make sure that `createCertificateAndKey() would not execute since a certificate is already available.`

Provide Hardware Entropy Source

In the mbedTLS version, the SDK uses /dev/urandom on Unix and CryptGenRandom API on Windows to get a strong entropy source. On some systems, these APIs might not be available. So, it's strongly suggested that you bring your own hardware entropy source. To do this, you need to follow these steps:

1. Uncomment MBEDTLS_ENTROPY_HARDWARE_ALT in configs/config_mbedtls.h
2. Write your own entropy source implementation by following this function signature: https://github.com/ARMmbed/mbedtls/blob/v2.25.0/include/mbedtls/entropy_poll.h#L81-L92
3. Include your implementation source code in the linking process

DEBUG

Getting the SDPs

If you would like to print out the SDPs, run this command: export DEBUG_LOG_SDP=TRUE

Adjust MTU

If ICE connection can be established successfully but media can not be transferred, make sure the actual MTU is higher than the MTU setting here: https://github.com/awslabs/amazon-kinesis-video-streams-webrtc-sdk-c/blob/master/src/source/PeerConnection/Rtp.h#L12.

You can also change settings such as buffer size, number of log files for rotation and log file path in the samples

Clang Checks

This SDK has clang format checks enforced in builds. In order to avoid re-iterating and make sure your code complies, use the scripts/check-clang.sh to check for compliance and scripts/clang-format.sh to ensure compliance.

Tracing high memory and/or cpu usage

If you would like to specifically find the code path that causes high memory and/or cpu usage, you need to recompile the SDK with this command: cmake .. -DLINK_PROFILER=ON

The flag will link the SDK with gperftools profiler.

Heap Profile

You can run your program as you normally would. You only need to specify the following environment variable to get the heap profile:

HEAPPROFILE=/tmp/heap.prof /path/to/your/binary

More information about what environment variables you can configure can be found here

CPU Profile

Similar to the heap profile, you only need to specify the following environment variable to get the CPU profile:

CPUPROFILE=/tmp/cpu.prof /path/to/your/binary

More information about what environment variables you can configure can be found here

Filtering network interfaces

This is useful to reduce candidate gathering time when it is known for certain network interfaces to not work well. A sample callback is available in Common.c. The iceSetInterfaceFilterFunc in KvsRtcConfiguration must be set to the required callback. In the sample, it can be done this way in initializePeerConnection(): configuration.kvsRtcConfiguration.iceSetInterfaceFilterFunc = sampleFilterNetworkInterfaces

Building on MacOS M1

When building on MacOS M1, if the build fails while trying to build OpenSSL or Websockets, run the following command: cmake .. -DBUILD_OPENSSL_PLATFORM=darwin64-arm64-cc

Building on 32 bit Raspbian GNU/Linux 11

To build on a 32-bit Raspbian GNU/Linux 11 on 64-bit hardware, the OpenSSL library must be manually configured. This is due to the OpenSSL autoconfiguration script detecting 64-bit hardware and emitting 64-bit ARM assembly instructions which are not allowed in 32-bit executables. A 32-bit ARM version of OpenSSL can be configured by setting 32-bit ARM platform: cmake .. -DBUILD_OPENSSL_PLATFORM=linux-armv4

Threadpool for Signaling Channel messages

The threadpool is enabled by default, and starts with 3 threads that it can increase up to 5 if all 3 are actively in use. To change these values to better match the resources of your use case please edit samples/Samples.h defines KVS_SIGNALING_THREADPOOL_MIN and KVS_SIGNALING_THREADPOOL_MAX. You can also disable the threadpool to instead create and detach each thread to handle signaling messages by commenting out KVS_USE_SIGNALING_CHANNEL_THREADPOOL.

Documentation

All Public APIs are documented in our Include.h, we also generate a Doxygen each commit for easier navigation.

Refer to related for more about WebRTC and KVS.

Development

If you would like to contribute to the development of this project, please base your pull requests off of the origin/develop branch, and to the origin/develop branch. Commits from develop will be merged into master periodically as a part of each release cycle.

Outbound hostname and port requirements

• KVS endpoint : TCP 443 (ex: kinesisvideo.us-west-2.amazonaws.com)
• HTTPS channel endpoint : TCP 443 (ex: r-2c136a55.kinesisvideo.us-west-2.amazonaws.com)
• WSS channel endpoint : TCP 443 (ex: m-26d02974.kinesisvideo.us-west-2.amazonaws.com)
• STUN endpoint : UDP 443 (ex: stun.kinesisvideo.us-west-2.amazonaws.com)
• TURN endpoint : UDP/TCP 443 (ex: 34-219-91-62.t-1cd92f6b.kinesisvideo.us-west-2.amazonaws.com:443)

The least common denominator for hostname is *.kinesisvideo.<region>.amazonaws.com and port is 443.

Related

• What Is Amazon Kinesis Video Streams with WebRTC
• JS SDK
• iOS SDK
• Android SDK

License

This library is licensed under the Apache 2.0 License.