We’re excited to announce the preview availability of the WebRTC 1.0 API, and support for the H.264/AVC and VP8 video codecs for RTC in Microsoft Edge, enabling plugin-free, interoperable video communications solutions across browsers and platforms.

These features are enabled by default in Windows Insider Preview builds starting with last week’s release, 15019, and will be in stable releases beginning with the Windows 10 Creator’s Update.

Background and Object RTC

Microsoft Edge introduced support for ORTC beginning in EdgeHTML 13 (Windows 10 version 1511), providing the initial foundation for real-time communications in Edge. Our priority with the WebRTC 1.0 API support is to provide interoperability with legacy implementations on existing websites, which leverage the WebRTC API as previously deployed in other browsers.

Our WebRTC 1.0 API implementation provides support for peer-to-peer audio and video based on a subset of the W3C WebRTC-PC API circa 2015, prior to the addition of the WebRTC object model.  Because this implementation is focused on legacy interoperability (including mobile applications built from early versions of the WebRTC.org source code), we don’t plan to further update the native WebRTC 1.0 API beyond this release.

To utilize the most advanced features in the Microsoft Edge RTC stack, we recommend that considering the ORTC API, especially in situations where it is desirable to control individual transport, sender, and receiver objects directly, or to set up group audio and video calls. If you need support for objects or advanced features such as multi-stream and simulcast with the current WebRTC 1.0 API, we recommend the adapter.js library, which now supports Microsoft Edge.

Codec interoperability

The H.264/AVC and VP8 video codecs are supported in the Microsoft Edge RTC stack, which means video communications are now interoperable between Microsoft Edge and other major WebRTC browsers and RTC services. We have implemented the following congestion control and robustness mechanisms for both H.264/AVC and VP8 video codecs:

• Support for the absolute send time header extension (abs-send-time)
• Support for Google Receiver Estimated Maximum Bitrate, “goog-remb”
• Support for Picture Loss Indication (PLI) and Generic NACK feedback messages, per RFC 4585
• Support for RTP Retransmission, per RFC 4588

These features are available within both the ORTC API and native WebRTC 1.0 API, so you can make API and video codec decisions independently.

Note that while the Edge H.264/AVC implementation supports hardware offload within both the encoder and decoder, VP8 is implemented purely in software, and as a result may exhibit higher power consumption and CPU load.  If your application uses VP8, we recommend testing on lower-end devices to ensure acceptable performance.

What’s next

As we continue to chart our roadmap for real-time communications, our next priorities are adding support for the W3C Screen Capture specification, as well as improved support for enterprise scenarios. We look forward to sharing updates and preview builds as the work progresses.  Meanwhile, we look forward to your feedback on WebRTC and our current RTC roadmap. You can try out WebRTC 1.0 in preview builds today, and if you encounter any bugs, share feedback on Microsoft Edge Platform Issues, via Twitter at @MSEdgeDev, or in the comments below.

― Shijun Sun, Principal Program Manager, Microsoft Edge
― Bernard Aboba, Principal Architect, Microsoft Skype

Updated January 31, 2017 10:07 am