Video conferencing

A few weeks ago we wrote an article about Docker and WebRTC servers and talked about the intricacies of launching containers. Our readers (rightly) questioned whether Docker was a suitable tool for production, for the following reasons:

The popularity of online education is increasing every month. And since there is an increase in popularity, there is an increase in competition and an improvement in quality: many authors of online schools realized that nowadays it's not enough to just make something mediocre using the frontal camera of the iPhone 4. You need to work on the quality of the picture, sound, presentation of material, etc. Not only did the pandemic prove that you can teach salsa and even crochet online, so it also gave an excellent push to improve the materials taught + diversity in the labor market. Moms on maternity leave can rejoice - now you can truly earn a hundred thousand million per second, sitting at home.

During the lockdown, which is now weakening, then becoming more active with a vengeance, a huge number of new professions have appeared. Proficients in creating involving Instagram Stories, course producers, e-learning specialists and other unknown-before-creatures - all of them have mastered a new job that gave them the holy bread in the pandemic. Once you hire a creator of involving Instagram Stories (and let's all hope this person was teached by a professional, not a snake oil salesman), your business grows just with adding some creativity in advertising that will take the heart of even the most fastidious customer. Same works with e-learning specialists: you recruit them and they do all the important tasks from writing articles that will also help in promoting your classes to arranging lessons on your Coursera course. A complete flight of imagination: if it seems to you that some jobs don't exist, then you just don't spend enough time online. In general, online work has become popularized as never and now hardly anyone will say: "He is engaged in some kind of garbage - he makes TikToks but it would be better for him to toil at the factory!". In total, online work has become popularized as never and now hardly anyone will say: "He is engaged in some kind of garbage - he makes TikToks, but it would be better for him to toil at the factory!".

In the previous article we refreshed our memory of WebRTC CDN and the ways this technology helps to minimize latency for WebRTC streams. We also discussed why load balancing and autoscaling wouldn't be amiss in CDNs. Here are the main points from the article:

The vast majority of IT specialists in various fields strive to perform manually as few actions as possible. I won't be afraid of the loud words: what can be automatized, must be automatized!

Let's imagine a situation: you need to deploy a lot of servers of the same type and do it quickly. Quickly deploy, quickly undeploy. For example, to deploy test rigs for developers. When development is carried out in parallel, you may need to separate the developers, so they don't impede each other and possible errors of one of them don't block the work of the others.

There may be several ways to solve this problem:

As you know, YouTube doesn't have a feature for capturing an RTSP stream, but we would like to change this and help YouTube to make their viewers happy.

Voice calling plays a crucial role in personal and professional communication. Be it a friendly conversation among classmates or a business deal between companies – voice calling has been the most easy, convenient, and affordable way to communicate for decades. Thus, communication corporations and developers have brought in innovative ways to integrate their Application Programming Interfaces (APIs) and invent newer ways of voice communication.

Alice is an experienced full stack developer, who is capable of writing a SAAS project framework on her favorite framework using php in a week. As for frontend, she prefers Vue.js. 

A client contacts you via Telegram, asking you to develop website that will be the meeting place for the employer and the employee to conduct an in-person interview. In-person means face-to-face, a direct video contact in real time with video and voice. «Why not use Skype?» some may ask. It just so happened that serious projects – and each startup undoubtedly considers itself a serious project – are trying to offer an internal communications service for a variety of reasons, including:

Virtual reality is on the rise these days. The equipment that was previously the exclusive preserve of crazy scientists geeks with big money from the Ministry of Defense back in the The Lawnmower Man days, is currently affordable for ordinary people; those whose pockets are empty, can assemble a VR headset from cardboard and a smartphone according to many recipes.

George shut his laptop and rubbed his sleep-deprived red eyes. "Customers continue to complain about stream freezing; the new fix package did not help at all! What do I do with this (censored) HLS?" he said.

The browser is not only hypertext, but also a streamer

Browsers have had players for a long time, but the story is different with the video encoder and streaming. Now, in almost any browser of the latest version, we can find modules for encoding, streaming, decoding, and playback. These functions are available through the JavaScript API, and the implementation is called Web Real Time Communications or WebRTC. This library built into browsers can do quite a lot: capture video from a built-in, virtual or USB camera, compress it with H.264, VP8, and VP9 codecs, and send it to the network via SRTP protocol; i.e., it functions as a software streamer video encoder. As a result, we see a browser that has something similar to ffmpeg or gstreamer, compresses video well, streams on RTP, and plays video streams.

Publish and Play

There exist two main functions of WebRTC operation on the server side in the field of streaming video: publishing and playing. In the case of publishing, the video stream is captured from the web camera and moves from the browser to the server. In the case of playing, the stream moves in the opposite direction, from the server to the browser, is decoded and played in the browser’s HTML5 <video> element on the device’s screen.

RTSP is a simple signaling protocol which they cannot replace with anything for many years already, and it has to be admitted that they don't try really hard.

For example, we have an IP camera that supports RTSP. Anyone who has ever tested the traffic with a Sharkwire cable will tell you that first there comes DESCRIBE, then PLAY, and then the traffic begins to pour directly via RTP or wrapped in the TCP channel for instance.

In the first part, we have deployed a simple dynamic CDN for broadcasting WebRTC streams to two continents and have proved on the example of a countdown timer that the latency in this type of CDN is actually low.

In the second part, we have incorporated dedicated servers into the CDN for performing the task of transcoding in order to provide good broadcast quality to our viewers based on the devices they use and the channel quality. In this manner, all published streams in our CDN are available to all the viewers.

Now, assume that a company is starting to introduce its monetization strategy where a number of streams should be available for free and the rest on a subscription basis. Or, for example, webinars for in-house staff training are broadcasted simultaneously, but each subsidiary has a separate stream, and disclosing the sales techniques used in Southeast Asia to the managers from CIS countries is undesirable.

In the first part we have deployed a simple dynamic CDN for broadcasting WebRTC streams to two continents and have proved on the example of a countdown timer that the latency in this kind of CDN is actually low.

However, besides low latency, it is important to provide good broadcast quality to users. After all, this is what they are paying for. In real life the channels between Edge servers and users can differ in bandwidth capacity and quality. For example, we are publishing a 720p stream at 2 Mbps, the user is playing it on an Android phone using 3G connection in an unstable signal reception area and the 360p maximum resolution that provides smooth picture at 400 Mbps is 360p.

Having analyzed earlier the capacity of standard server configurations in Digital Ocean in terms of WebRTC streaming, we have noticed that one server can cover up to 2000 viewers. In real life, cases when one server is insufficient are not uncommon.

Assume gambling amateurs in Germany are watching real-time horse races in Australia. Given that horse races are not only a sports game but also imply big gains on condition that field bets are made at the right time, the video has to be delivered with lowest possible latency.

Another example: A global corporation, one of FCMG market leaders with subsidiaries in Europe, Russia and Southeast Asia, is organizing sales manager training webinars with live streaming from the headquarters in the Mediterranean. The viewers must be able to see and hear the presenter in real time.