WebRTC and gstreamer on linux device

Question

I have small computer (something like Arduino or Raspberry pi) with Linux, camera and gstreamer installed on it. I need to stream h264 video from this device to browser using WebRTC technology. Also, I use NodeJS as signaling server.

In simple words, I need to doing a WebRTC client from my device. What is the best way to do this? Can I use WebRTC Native API for this goal? How can I install it on my small device? Or, maybe, I just need to play with my gstreamer and install some webrtc plugins for it?

Answer 1

Since you will have to use a signalling server anyways, I would say you should use the Janus-Gateway. You mention CentOS for your signalling server, I am not 100% if it will run on CentOS specifically, but I have ran it successfully in Debian Jessie build with just a few dependency installations.

Janus handles the entire call set up with the gateway(signalling and everything). So, some port forwarding will probably have to be done so that the SDP exchange can occur(which you would have to worry about with any signalling server).

• Install the gateway, there are a few dependencies but all were simple installations

• Take a look at the janus_streaming plugin. It has a gstreamer example that will stream from a gstreamer pipeline. Also, the streamingtest demo page to see how the Javascript API works for that plugin

• The plugin listens on those ports given in the configuration file and will accept traffic from any IP address. So, I expect you can run a gstreamer pipeline on a different machine on the same network and send it to the plugin.

NOTE: You will have to modify the SDP that the JavaScipt sends to the gateway so that it includes H264(probably get rid of all other codecs as well just to force negotiation). You can do this by accessing the sdp through the jsep object passed to the success case for the createOffer function in the janus JavaScript API(jsep.sdp).

Answer 2

For WebRTC for Raspberry Pi 2 you may want to consider UV4L. It allows you to stream live Audio & Video from the Rpi to any browser on a PC (HTML5).

Answer 3

Another possibility for you is to use the Kurento Media Server (KMS), which has been written on top of GStreamer. I see two possibilities

1. You install KMS in a Ubuntu 14.04 box and bridge with your device, so that the device generates the video stream and sends it to the KMS box. From that, you can transcode it to VP9 and distribute it as a WebRTC stream quite easily using kurento client APIs (which may be used from Node.js). The application making the transcoding will require an RtpEndpoint (receiving video form the device in RTP/H.264) connected to a WebRtcEndpoint (capable of sending the video stream through WebRTC). This option is quite simple to implement because it's the standard way of using KMS. However, you will need to generate the RTP/H.264 stream on the device and appropriate SDP for it (this can be done using standard GStreamer elements)
2. You try to install KMS into your box directly. This might be more complex because it requires compiling KMS to the specific device, which may require some time investment. In addition, performing the transcoding in the device might be too expensive and you could starve its CPU.

Disclaimer: I'm member of the Kurento development team

Answer 4

You mentioned that you used a NodeJS signaling server. Recently Ericsson released an open source WebRTC gstreamer element: http://www.openwebrtc.io/, and along with their release they also published a WebRTC demo using node.js: http://demo.openwebrtc.io:38080/; the code here: https://github.com/EricssonResearch/openwebrtc-examples/tree/master/server.