Multimedia streaming over the Internet has seen rapid user adoption. In the US, Netlfix overtook Comcast in subscription numbers. There are several services (other than the ones RIAA/MPAA doesn’t want you to use) that offer online streams for content. Youtube, Netflix and Hulu to name a few popular ones. Microsoft introduced Silverlight (their Flash alternative) a while back. One of the features Microsoft talked about with Silverlight was adaptive streaming. In simplest terms, it is a concept where the quality of stream automatically adjusts to your Internet connection speed—in real time. So if your Internet connection gets clogged during an ongoing stream, it will switch to a low resolution (low bitrate) version on its own.

Microsoft calls this Smooth Streaming and has a lot of technical magic in the background. Smooth Streaming has helped Microsoft clinch several live event streaming deals which in turn have resulted in Silverlight getting a considerable user base. I recently came across a patent titled Seamless switching of scalable video bitstreams. The patent claims are concepts behind Smooth Streaming. Excerpts from the claims:

A computer-implemented method executable on a processor for switching between a first bitstream and a second bitstream, wherein the second bitstream provides a higher data rate than the first bitstream, the method comprising: identifying a switching up period associated with the first and second bitstreams, the first bitstream comprising first encoded data for a plurality of frames within a video sequence [...]

An apparatus suitable for encoding a first bitstream and a second bitstream, wherein the second bitstream provides a higher data rate than the first bitstream, the apparatus comprising: a memory; one or more processors; an interface, operable on the one or more processors, configurable to selectively output the first and second bitstreams; and logic operatively coupled to the interface and configured to selectively encode a plurality of frames of a video sequence [...]

Given the importance of Intellectual Property as observed recently, Microsoft being awarded this patent is quite interesting. My quick not-so-in-depth searches show that neither Netflix nor Hulu have patents on online video streaming (I could be wrong though). I haven’t played a lot with Netflix but Hulu offers an option to Auto-select best quality for the bandwidth available. Although, I don’t see Microsoft going after Hulu.

As it turns out, Adobe has a similar feature called Dynamic Streaming that they use in Flash and Apple uses a similar implementation for streaming their events to iOS and OS X powered devices. According to the patent, Microsoft filed for it back in 2005.

Other than Silverlight based streaming, Microsoft offers video streams on the Xbox too. A demo of Smooth Streaming over IIS is available here.

The Patent