What DASH is
MPEG DASH is a codec agnostic standard for adaptive streaming over HTTP. Like HLS it serves segments and a manifest, but its manifest is an XML document called the MPD, the media presentation description.
Structure of the MPD
- Period is a time span of the presentation, used for ad breaks or chapters.
- Adaptation set groups one media type such as video or audio.
- Representation is one rendition at a given bitrate.
- Segments are addressed by a template or an index.
Segment addressing
DASH often uses a segment template so the player computes each segment URL from a pattern and number, rather than listing every file. This keeps the manifest small even for long content and live streams.
DASH versus HLS
DASH is an open standard and codec agnostic, while HLS originated from one vendor and is widely supported on its devices. Many services package both from the same renditions and pick by client. The common media format lets one set of segments feed both, halving storage.
Key idea
DASH is a codec agnostic HTTP streaming standard whose XML MPD describes periods, adaptation sets, and representations, often addressing segments by template.