I see WebRTC is the the best way for developing it. But there are some paid frameworks in market for establisting video chat between wide range of clients like Web-Web, Web-Mobile(IOS, Andriod, Windows, etc.,).
Web-Web communication flow is very simple to implement. Now, I want the same for Web-to-Mobile and vice versa without using any external frameworks built on top of Native WebRTC. Please suggest me some best approach to achieve this.
The latest Chrome on Android is WebRTC friendly, that means if you have a web app that implements WebRTC. It will be working on Android's Chrome.
If you decided to create you own native app that implements WebRTC. Here are some great sources.
Follow the instructions in each allow you to build the native WebRTC framework that you can later on import them into your native projects.
The WebRTC APIs are somewhat related to the ones you are using in your web application. You need to do more documentation reading for those as you are using the official framework that built from the source, not a third library.
Before starting you need to review and test platform to make sure it works fine for all your target user categories. You can do that by reviewing references and also testing some existing apps for user types you plan to support.
As you mentioned wide range of clients, you need to identify the limitations of WebRTC technology. You can also evaluate other technologies: in example you could reliably serve most client types with mobile and web apps that use RTMP.
