GlossarySmooth Streaming

Smooth Streaming

Smooth Streaming is Microsoft's adaptive bitrate streaming protocol, launched for Silverlight, that delivers video over HTTP in small fragments at several quality levels. It uses fragmented MP4 files and an XML manifest. Smooth Streaming helped prove that HTTP-based adaptive streaming works at scale, and its ideas shaped MPEG-DASH, but it is now a legacy format.

Why it matters

Smooth Streaming is mostly a legacy concern now. Companies that still serve older smart TVs, game consoles or set-top boxes may need it, which means extra packaging and testing. Moving those devices to DASH or HLS reduces formats to maintain and cuts operating cost.

How it works

  1. Video is encoded at several bitrates and stored as fragmented MP4 files.
  2. An XML client manifest lists the available quality levels and audio tracks.
  3. The player requests fragments by time and bitrate over standard HTTP.
  4. The player switches quality level between fragments as bandwidth changes.

Is Smooth Streaming still used?

Only in legacy setups. Silverlight, the plugin it was built for, is retired, and most streaming services have moved to DASH and HLS. Some older smart TVs, Xbox apps and set-top boxes still expect Smooth Streaming with PlayReady DRM, so a few services keep it for those devices while they phase them out.

Smooth Streaming vs DASH: what is the difference?

Smooth Streaming is Microsoft's proprietary protocol, while DASH is an open ISO standard that borrowed many of its ideas. Both use fragmented MP4 and an XML manifest. DASH is far more widely supported today across browsers, Android and smart TVs, so new services choose DASH or HLS instead.

Where it's used

Streaming services supporting older smart TVs, Xbox apps or set-top boxes still meet Smooth Streaming, though most broadcasters and OTT services have moved those workflows to DASH and HLS.

By the numbers

  • In November 2010, IIS Media Services 4.0 could repackage live Smooth Streaming H.264 and AAC video into Apple's HLS format for iOS devices without re-encoding. (Smooth Streaming, Wikipedia)

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