Add 'mode' attribute to SourceBuffer, and support the ability to use and switch among 'sequence' and 'segments' appendMode. 'segments' is the default (and current) behavior. 'sequence' enables web developers to simplify some types of media streaming apps that use Media Source Extensions (MSE). 'sequence' appendMode allows more flexibility to maintain a gap-free buffered media timeline for web apps.



Specification link

Specification being incubated in a Community Group

Status in Chromium


Enabled by default (tracking bug)

Consensus & Standardization

After a feature ships in Chrome, the values listed here are not guaranteed to be up to date.



'sequence' AppendMode also allows a simpler migration path for current MSE players who may wish to switch from an MSE bytestream which uses 'generate timestamps flag' (audio/mpeg or audio/aac) to other bytestreams which require more app-directed control of where media appends occur in the timeline to obtain a similar result as 'sequence' enables.

Search tags

AppendMode, SourceBuffer, mode, segments, sequence, timestampOffset,

Last updated on 2021-05-05