This specification defines the byte stream formats for use with the specification [[MEDIA-SOURCE]].

The working group maintains a list of all bug reports that the editors have not yet tried to address; there may also be related open bugs in the [[MEDIA-SOURCE]] repository.

Implementors should be aware that this specification is not stable. Implementors who are not taking part in the discussions are likely to find the specification changing out from under them in incompatible ways. Vendors interested in implementing this specification before it eventually reaches the Candidate Recommendation stage should join the mailing list mentioned below and take part in the discussions.


This registry is intended to enhance interoperability among implementations and users of SourceBuffer objects described in the (MSE) specification. In particular, this registry provides the means (1) to identify and avoid MIME-type collisions among byte stream formats, and (2) to disclose information about byte stream formats accepted by MSE implementations to promote interoperability.


The registry maintains a mapping between MIME-type/subtype pairs and byte stream format specifications. The byte stream format specifications describe the structure and semantics of byte streams accepted by SourceBuffer objects created with the associated MIME-type/subtype pair.

This registry is not intended to include any information on whether a byte stream format is encumbered by intellectual property claims. Implementors and users are advised to seek appropriate legal counsel in this matter if they intend to implement or use a specific byte stream format.

Registration Entry Requirements

  1. Each entry MUST include a unique MIME-type/subtype pair. If the byte stream format is derived-from an existing file format, then it SHOULD use the MIME-type/subtype pairs typically used for the file format.
  2. Each entry MUST include a value that MUST be used by SourceBuffer when handling the byte stream format.
  3. Each entry MUST include a link that references a publically available specification. It is recommended that such a specification be made available without cost (other than reasonable shipping and handling if not available by online means).
  4. Each entry MUST comply with all requirements outlined in the of the specification [[!MEDIA-SOURCE]].
  5. Candidate entries MUST be announced on (subscribe, archives) so they can be discussed and evaluated for compliance before being added to the registry.

If a registration fails to satisfy a mandatory requirement specified above, then it MAY be removed from the registry (without prejudice).


MIME type/subtype Public Specification(s) Generate Timestamps Flag
[[!MSE-FORMAT-WEBM]] false
[[!MSE-FORMAT-MP2T]] false