vidpickr

Glossary · protocol

What is DASH (MPEG-DASH)?

DASH (Dynamic Adaptive Streaming over HTTP) is an open streaming protocol. Like HLS, it chunks the video into short segments and provides a manifest (.mpd) listing them. YouTube's primary delivery format is DASH; the player picks segments and qualities adaptively based on connection speed.

Also called:mpeg-dash · mpd · adaptive streaming

DASH was created as a vendor-neutral alternative to HLS. It uses fragmented MP4 segments (sometimes WebM) and an XML manifest. The protocol is what powers YouTube's adaptive streaming: when your connection drops, the player switches to a lower-quality segment for the next chunk without interrupting playback.

For downloaders, DASH is mostly invisible: you fetch the underlying segments' video and audio URLs and mux them together. VidPickr does exactly that — pulls the highest-quality DASH segments YouTube serves for the chosen resolution and assembles them into a single playable file.

Common questions

Is DASH proprietary?
No, DASH is an ISO-standardized open protocol (ISO/IEC 23009). It's royalty-free in spec; some implementations may have patent encumbrances on the codecs they carry.

Related terms

HLS (HTTP Live Streaming)

HLS (HTTP Live Streaming) is a streaming protocol developed by Apple.

Fragmented MP4

Fragmented MP4 (fMP4) is an MP4 variant where the file is split into many short chunks ("fragments"), each containing its own header.

Manifest (streaming)

A manifest is a small text file that lists every segment of a streaming video, plus available qualities, codecs, and timing.

VidPickr is a free, browser-based YouTube downloader. Every term in this glossary either describes how YouTube delivers video or why your downloads behave the way they do. Try the downloader →