TelmateFrameGrabber

Introduction:

This module implements a Kurento endpoint frames grabber.

The module uses the Kurento OpenCV support and receive reference to a opencv cv::mat object containing the frame data and saves it to disk.

An instance of this module is created for each Kurento endpoint, the instance implements a process() function which is called by the Kurento plugin-core for each frame. A process() function creates a VideoFrame object in the heap, performs a deep copy of the Mat object and adds a timestamp. The VideoFrame object ptr is then pushed into a variable sized boost::lockfree::queue.

Upon plugin initialization a queue handler thread is created with thread main function set to queueHandler(). This function pops VideoFrames pointers from the boost::lockfree::queue and uses the Mat object data to save a PNG image to the disk.

Design

The plugin is designed around a lock-free thread-safe producer-consumer pattern to ensure speed and proper usability under system load and slow IO as the Kurento plugin subsystem is implemented serially. (plugins are actually filters) each video frame through the plugin potentially creating an issue.

Compiling:

All basic Kurento libraries are needed as mentioned in How to Develop Kurento Modules

Please make sure Boost C++ and OpenCV and all -dev packages are installed.

To build the Java bindings, Maven is needed.

git clone https://github.com/avis/TelmateFrameGrabber

cd TelmateFrameGrabber/module
mkdir build # a place to build the code in.
cd build
cmake -DCMAKE_INSTALL_PREFIX=/usr .. # TO generate the C++ code bindings.
cmake .. -DGENERATE_JAVA_CLIENT_PROJECT=TRUE # To generate the Java bindings.
make
make install

To comilple the java bindings:

cd java
mvn compile exec:java

Testing:

The kurento-one2one-videocall-java includes a modified version of the original proof of concept one2one video call application. This application - once executed, exposes an http server on port 8443. For testing purposes, the HTTP service this application exposes could be accessed using two different browser tabs on a client machine and provide a simple loopback video call where the two endpoints are really the same video camera and microphone. The app will start the TelmateFrameGrabber plugin and save PNG snapshots to the Kurento media server /tmp directory. To compile and execute the app:

export KURENTO_SERVER_ADDRESS=192.168.1.1
mvn compile exec:java -Dkms.url=ws://$KURENTO_SERVER_ADDRESS:8888/kurento

Public Methods:

• void setSnapInterval(int snapInterval): Optional, Recommended, Sets the snapshot interval (in milliseconds). Defaults to 1000ms.

• void setStoragePath(const std::string &path): Optional, Recommended, Sets the storage path location. Defaults to /tmp.

• void setWebRtcEpName(const std::string &epName): Optional, Sets the endpoint name. Defaults to NULL.

• int getSnapInterval(): Returns the current configured snapshot interval.

• std::string getStoragePath(): Returns the current configured snapshots path.

• void setOutputFormat(int outputFormat): Optional, Recommended, Sets the output format for images (0x0=JPEG 0x1=PNG). Defaults to JPEG.

Classes:

• TelmateFrameGrabberImpl: Kurento Plugin. This class is an interface between the Kurento plugin core and the actual plugin.

• TelmateFrameGrabberOpenCVImpl: This Class implements the plugin, Interacts with TelmateFrameGrabberImpl.

• VideoFrame: This class is a storage object for video frames pushed into the queue.

Authors:

Avi Saranga - Telmate.

Licensing:

MIT License

Copyright (c) 2017 Telmate, LLC

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.