vidpickr

Glossary · protocol

What is Manifest (streaming)?

A manifest is a small text file that lists every segment of a streaming video, plus available qualities, codecs, and timing. HLS uses .m3u8 manifests; DASH uses .mpd. The player downloads the manifest first, then fetches segments based on its instructions.

Also called:m3u8 · mpd · streaming manifest

Streaming protocols separate metadata from media. The manifest is tiny (a few kilobytes) and downloads instantly; it tells the player what segments exist, where to fetch them, what codecs and bitrates are available. Then the player can adaptively pull just the segments and qualities it needs.

For a YouTube video, the manifest equivalent (delivered through DASH) lists video segments at every quality (144p through 8K), audio segments in every available language, and the timing offsets so the player can sync them. Downloaders read the manifest to discover which streams to fetch.

Common questions

Where is the manifest in a YouTube video page?
YouTube's player constructs an in-memory manifest from the response of the player API call. There is no public .m3u8 or .mpd URL exposed on the watch page; clients reconstruct the equivalent from the player config JSON.

Related terms

HLS (HTTP Live Streaming)

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

DASH (MPEG-DASH)

DASH (Dynamic Adaptive Streaming over HTTP) is an open streaming protocol.

Fragmented MP4

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

Signed URL

A signed URL is a download link with cryptographic parameters that authenticate the request and expire after a set time.

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 →