Live IIS Smooth Streaming

HTTP Streaming with IIS Smooth Streaming

streaming video hosting, content management, optimized global delivery.

Live IIS Smooth Streaming


IIS Media Services, is a HTTP-based streaming method (like Apple HTTP Live Streaming or Adobe’s HTTP Dynamic Streaming), capable of true HD (720p+) live and on-demand content video streaming, DVR functionality, and real-time analytics support to computers, TVs, and mobile devices.


Our global CDN is built out to broadcast your live video with IIS Smooth Streaming, Microsoft’s HTTP live streaming solution and evolution of Windows Media Services.


Internet Information Services (IIS) offers an HTTP-based adaptive streaming extension (Live Smooth Streaming). That is just a technical way to say that the Live Smooth Streaming adapts to the user’s streaming bandwidth environment, on the fly.


This ‘dynamic switching’ of bit rate streams is based not only on your audience member’s bandwidth, bt also their CPU usage. In other words, stream quality is improved to match a user’s computing environment, as long as that client’s computer is sufficiently powerful to handle the live smooth streaming to begin with. By adapting dynamically you can deliver the highest quality stream your audience is likely to receive.


Trying to decide between live IIS Smooth Streaming or Apple HTTP Live Streaming? Take a look at a demo of IIS Smooth Streaming at and compare that with a (more humble) demo of Apple HTTP Live Streaming here at, for a very basic comparison.


What does dyncamic bit rate switching do and how does it help my live webcast?


A ‘Bitrate’ is a unit of measurement that refers to the speed of data transfer across a network, often in Kb per second or kbps (1000 bits per second). This number correlates with potential bandwidth level that a user has at any particular moment.


If a client’s bandwidth or CPU usage is not sufficient for the current stream, then the video stream will be seamlessly switched to a lower quality. Likewise, a client’s bitrate will be increased (up to the maximum quality you are encoding your live stream at) automatically if their bandwidth improves.


What are the advantages of live IIS Smooth Streaming?



Smooth Streaming technology enables adaptive streaming of media to Microsoft Silverlight and other Smooth Streaming clients over HTTP. Smooth Streaming provides a high-quality viewing experience that scales massively on content distribution networks, making full HD media experiences (1080p+) a reality. The technology relies on Windows 2008 Server and Internet Information Services (IIS) Media Services technology.

Smooth Streaming dynamically detects local bandwidth and video rendering conditions and seamlessly switches, in near real time, the video quality of a media file that a player receives. Consumers with high-bandwidth connections can experience high definition (HD) quality streaming, while others with lower bandwidth speeds receive the appropriate stream for their connectivity, allowing consumers across the board to enjoy a compelling, uninterrupted streaming experience, and alleviating the need for media companies to cater to the lowest common denominator quality level within their audience base.

IIS Smooth Streaming uses the MPEG-4 Part 14 (ISO/IEC 14496-12) file format as its disk (storage) and wire (transport) format. Specifically, the Smooth Streaming specification defines each chunk/GOP as an MPEG-4 Movie Fragment and stores it within a contiguous MPEG-4 file (.MP4) for easy random access. One MPEG-4 file is expected for each bitrate. When a client requests a specific source time segment from the IIS Web server, the server dynamically finds the appropriate MPEG-4 Movie Fragment box within the contiguous file and sends it over the wire as a standalone file, thus ensuring full cacheability downstream (See Figure 2, below).

In other words, with Smooth Streaming, file chunks are created virtually upon client request, but the actual video is stored on disk as a single full-length file per encoded bitrate. This offers tremendous file-management benefits.

Smooth Streaming content is played using the Microsoft Silverlight 2 (or higher) Internet browser plug-in. All of the functionality, such as the parsing of the MPEG-4 file format, HTTP downloading, bit rate switching heuristics, and more is provided in the Smooth Streaming client, which is written in Microsoft .NET code and runs as a managed plug-in to Silverlight. This provides an easy way to modify and fine-tune the client adaptive streaming code as needed, instead of waiting for the next release of the Silverlight runtime.

The most important part of Smooth Streaming client development is the heuristics module that determines when and how to switch bitrates. Simple stream switching functionality requires the ability to swiftly adapt to changing network conditions while not falling too far behind, but that’s often not enough to deliver a great experience. The IIS Smooth Streaming Media Element (SSME) was created as a platform layer for Silverlight 3 that includes tunable heuristics, allowing publishers to more simply build experiences without requiring them to understand underlying details. This platform layer provides developers with a rich interface that is similar to ones that Silverlight developers are already familiar with. In addition, this layer also allows developers and third parties to more easily integrate additional rich functionality with Smooth Streaming, including analytics, advertising, DVR (such as Pause, Seek, Rewind, Fast Forward), rough cut editing, multiple camera angles, multiple languages, and DRM.

Even in its most basic usage, SSME addresses the following cases:

 Where a user has low or variable bandwidth
 Where a user has enough bandwidth but doesn’t have enough resources (such as CPU cycles or RAM) to render the higher resolution video
 When the video is paused or hidden in the background (minimized browser window)
 When the resolution of the best available video stream is actually larger than the screen resolution, thus potentially wasting bandwidth
 Seamless rollover to new media assets, such as advertisements