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webrtcH4cKS: ~ RED: Improving Audio Quality with Redundancy

Posted by Philipp Hancke on August 20, 2020
Posted in: Reverse-Engineering, Standards, Technology.
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Back in April 2020 a Citizenlab reported on Zoom’s rather weak encryption and stated that Zoom uses the SILK codec for audio. Sadly, the article did not contain the raw data to validate that and let me look at it further. Thankfully Natalie Silvanovich from Googles Project Zero helped me out using the Frida tracing tool and provided a short dump of some raw SILK frames. Analysis of this inspired me to take a look at how WebRTC handles audio. In terms of perception, audio quality is much more critical for the perceived quality of a call as we tend to notice even small glitches. Mere ten seconds of this audio analysis were enough to set me off on quite an adventure investigating possible improvements to the audio quality provided by WebRTC. ...  Continue reading

webrtcH4cKS: ~ Using getDisplayMedia for local recording with audio on Jitsi

Posted by Chad Hart on June 30, 2020
Posted in: Guide.
Tagged: , , , .
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local Jitsi recording hack with getDisplayMedia audio capture and mediaRecorder

I wanted to add local recording to my own Jitsi Meet instance. The feature wasn’t built in the way I wanted, so I set out on a hack to build something simple. That lead me down the road to  discovering that:

  1. getDisplayMedia for screen capture has many quirks,
  2. mediaRecorder for media recording has some of its own unexpected limitations, and
  3. Adding your own HTML/JavaScript to Jitsi Meet is pretty simple

Read on for plenty of details and some reference code. My result is located in this repo.

Want to keep up on our latest posts? Please click here to subscribe to our mailing list if you have not already. We only email post updates. You can also follow us on twitter at @webrtcHacks for blog updates. ...  Continue reading

webrtcH4cKS: ~ Open Source Cloud Gaming with WebRTC

Posted by Thanh Nguyen on April 15, 2020
Posted in: Technology.
Tagged: , , , .
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Software as a Service, Infrastructure as a Service, Platform as a Service, Communications Platform as a Service, Video Conferencing as a Service, but what about Gaming as a Service? There have been a few attempts at Cloud Gaming, most notably Google’s recently launched Stadia. Stadia is no stranger to WebRTC, but can others leverage WebRTC in the same way?

Thanh Nguyen set out to see if this was possible with his open source project, CloudRetro. CloudRetro is based on the popular go-based WebRTC library, pion (thanks to Sean of Pion for helping review here). In this post, Thanh gives an architectural review of how he build the project along with some of the benefits and challanges he ran into along the way. ...  Continue reading

webrtcH4cKS: ~ True End-to-End Encryption with WebRTC Insertable Streams

Posted by Philipp Hancke on April 12, 2020
Posted in: Guide.
Tagged: , , , .
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A couple of weeks ago, the Chrome team announced an interesting Intent to Experiment on the blink-dev list about an API to do some custom processing on top of WebRTC. The intent comes with an explainer document written by Harald Alvestrand which shows the basic API usage. As I mentioned in my last post, this is the sort of thing that maybe able to help add End-to-End Encryption (e2ee) in middlebox scenarios to WebRTC.

I had been watching the implementation progress with quite some interest when former webrtcHacks guest author Emil Ivov of jitsi.org reached out to discuss collaborating on exploring what this API is capable of. Specifically, we wanted to see if WebRTC Insertable Streams could solve the problem of end-to-end encryption for middlebox devices outside of the user’s control like Selective Forwarding Units (SFUs) used for media routing. ...  Continue reading

webrtcH4cKS: ~ Accelerated Computer Vision inside a WebRTC Media Server with Intel OWT

Posted by Chad Hart on April 3, 2020
Posted in: Guide.
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WebRTC has made getting and sending real time video streams (mostly) easy. The next step is doing something with them, and machine learning lets us have some fun with those streams. Last month I showed how to run Computer Vision (CV) locally in the browser. As I mentioned there, local is nice, but sometimes more performance is needed so you need to run your Machine Learning inference on a remote server. In this post I’ll review how to run OpenCV models server-side with hardware acceleration on Intel chipsets using Intel’s open source Open WebRTC Toolkit (OWT). ...  Continue reading

webrtcH4cKS: ~ Does your video call have End-to-End Encryption? Probably not..

Posted by Philipp Hancke on April 1, 2020
Posted in: Standards.
Tagged: , , , .
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Time for another opinionated post. This time on… end-to-end encryption (e2ee). Zoom apparently claims it supports e2ee while it can not satisfy that promise. Is WebRTC any better?

Zoom does not have End to End Encryption

Let’s get to the bottom of things fast: Boo Zoom!

I reviewed how Zoom’s implements their web client last year.

I’m not really surprised of their general lack of e2ee given that their web client did not provide any encryption on top of TLS or WebRTC’s DataChannel. For reasons we will discuss below, this means they weren’t doing any obvious e2ee there. ...  Continue reading

webrtcH4cKS: ~ Stop touching your face using a browser and TensorFlow.js

Posted by Chad Hart on March 19, 2020
Posted in: Guide.
Tagged: , , .
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Don’t touch your face! To prevent the spread of disease, health bodies recommend not touching your face with unwashed hands. This is easier said than done if you are sitting in front of a computer for hours.  I wondered, is this a problem that can be solved with a browser?

We have a number of computer vision + WebRTC experiments here. Experimenting with running computer vision locally in the browser using TensorFlow.js has been on my bucket list and this seemed like a good opportunity. A quick search revealed somebody already thought of this 2 week ago. That site used a model that requires some user training – which is interesting but can make it flaky. It also wasn’t open source for others to expand on, so I did some social distancing via coding isolation over the weekend to see what was possible. ...  Continue reading

webrtcH4cKS: ~ Private Home Surveillance with the WebRTC DataChannel (Ivelin Ivanov)

Posted by Ivelin Ivanov on February 25, 2020
Posted in: Guide.
Tagged: , .
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When most people think of WebRTC they think of video communications. Similarly, home surveillance is usually associated with video streaming. That’s why I was surprised to hear about a home security project that leverages WebRTC not for video streaming, but for the DataChannel. WebRTC’s DataChannel might not demo as well as a video call, but as you will see, it is a very convenient way to setup peer-to-peer information transfer.

Ivelin Ivanov is a long-time open source contributor in a variety of projects and organizations like RedHat, Mobicents, and Telestax. Recently he started to address some home IoT privacy concerns with a new open source project, Ambianic. His project includes many interesting elements, including computer vision on a Raspberry Pi (one of my favorite topics), but for this post I asked him to talk about how he leveraged WebRTC and the DataChannel in his architecture.  ...  Continue reading

webrtcH4cKS: ~ Not a Guide to SDP Munging

Posted by Philipp Hancke on February 11, 2020
Posted in: Standards.
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SDP has been a frequent topic, both here on webrtcHacks as well as in the discussion about the standard itself. Modifying the SDP in arcane ways is referred to as SDP munging. This post gives an introduction into what SDP munging is, why its done and why it should not be done. This is not a guide to SDP munging.

Want to keep up on our latest posts? Please click here to subscribe to our mailing list if you have not already. We only email post updates. You can also follow us on twitter at @webrtcHacks for blog updates. ...  Continue reading

webrtcH4cKS: ~ Perfect Negotiation

Posted by Chad Hart on February 5, 2020
Posted in: Standards.
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Series preface: We generally lean toward long posts here at webrtcHacks, but not all interesting topics warrant a lot of new text. Sometimes briefer is better. So to better address the many topics that fit into this category, we are starting a new Minimum Duration series. Here is our first post under this set covering Perfect Negotiation.

What is Perfect Negotiation and why do we need it?

Long ago the WebRTC specification designers settled on leaving the signaling communication mechanism between two WebRTC peers up to the application. This means your code needs to handle passing Session Description Protocol (SDP) back and forth and giving that to the peerConnection API. Today WebRTC implementations also almost universally use Trickle-ICE, a form of Interactive Connectivity Establishment (ICE), which passes potential network paths between those peers asynchronously so a connection can be established as soon as possible. The asynchronous but time sensitive nature of all this means it is possible for glare conditions to occur – situations where both sides are making updates at the same time causing their state machines to get out of sync. Differences in how developers implement their code and browsers variances make this worse. ...  Continue reading