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Bit Rate Throttling

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Bit Rate Throttling, an IIS Media Services extension, saves money on network costs by metering the download speed of media and data files. For media, Bit Rate Throttling accomplishes this by automatically detecting the encoded bitrates of 11 common media formats, such as Windows Media Video (WMV), Flash Video (FLV), and MPEG-4 (MP4), and then throttling the response to the client. For any other file or MIME type, Bit Rate Throttling allows administrators to configure custom throttling rules.

Reduce bandwidth costs without compromising user experiences

Bit Rate Throttling saves network bandwidth costs by controlling the rate at which media is delivered over HTTP. The throttling rate can be configured using server-side rules or by automatically adjusting the download rate for detected media files based on format and encoded bitrate. When Bit Rate Throttling is not used, content is downloaded at the maximum possible speed. If a user watches only 20% of a video clip, the hoster would have paid bandwidth for content that was never watched.

When Bit Rate Throttling is used, a few seconds of content is sent to the client at the highest possible data rate before throttling down delivery to the encoded bitrate so that users experience a "Fast Start" of the content they want to watch.

Share extra bandwidth among all users with dynamic throttling

Bit Rate Throttling also allows you to dynamically split your total available bandwidth allocation across all concurrent users. If you're billed for network usage based on a 95th percentile billing model rather than per-byte of data transferred, this equitably shares extra available bandwidth among all of your users. As new users start to consume the extra bandwidth, dynamic throttling reduces bandwidth to each user, but ensures that the allocated bandwidth for each user will not fall below the specified bitrate for the content being consumed.

Extend throttling to other content types

Bit Rate Throttling allows you to add automatic detection and throttling support for other media file formats through its extensible architecture. You can also simply specify fixed-rate throttling for any file or MIME type, media or otherwise, by adding new throttle settings. If you need to vary the throttling rate on a per-response basis, Bit Rate Throttling also allows programmatic throttling configuration.


  • Seamless integration with IIS Manager
  • Out-of-the box compatibility for the following media types: .asf, .avi, .flv, .m4v, .mov, .mp3, .mp4, .rm, .rmvb, .wma and .wmv
  • Dynamic throttling adjustment based on:
    • The file types and their encoded bitrate
    • The available connection bandwidth
    • Default and maximum throttling rates
    • Concurrent connection limits
    • Target throughput rate for the website
  • Throttling rules configurable at various levels including server, website, and virtual directory
  • Fast Start for optimal user experience
  • Extensibility to enable other media formats and file types
  • Better-together solution when combined with the Web Playlists extension

Download IIS Media Services 4.1