What is HTTP Smooth Streaming?
HTTP Smooth Streaming is a Microsoft adaptive streaming technology that delivers fragmented MP4 media as small HTTP chunks. A manifest describes available tracks and quality levels.
How HTTP Smooth Streaming works
Smooth Streaming organizes encoded tracks as fragmented MP4 chunks and exposes their available qualities through an XML client manifest. The player selects chunks by track and timestamp, allowing independent audio or video quality decisions during a session. Server-side publication information and client-facing metadata play different roles in the ecosystem. It occupies the same adaptive-delivery layer as modern HLS and DASH, but its conventions reflect Microsoft’s earlier Silverlight and IIS media stack.
Key facts
- 1Smooth Streaming URLs commonly identify a track by bitrate and request a fragment by start time, so preserving timeline values is essential when moving or proxying an existing presentation.
- 2Its client manifest is generally identified by the .ismc convention, while server manifests can describe source tracks; neither is syntactically compatible with M3U8 or DASH MPD manifests.
- 3The media uses fragmented ISO Base Media structures, which may permit compressed samples to be reused during migration, but manifests, chunk addressing, and protection signaling still need conversion.
When HTTP Smooth Streaming matters
Developers encounter Smooth Streaming in older IIS and Microsoft media deployments. Migration or compatibility work must preserve chunk timing, codecs, manifests, and any content protection.