Encrypted Media Extensions Stream Format Registry

W3C Editor's Draft

This version:
Latest published version:
Latest editor's draft:
Joey Parrish (Google Inc.)
Greg Freedman (Netflix Inc.)
Former editors:
Mark Watson (Netflix Inc.) (Until September 2019)
David Dorwin (Google Inc.) (Until September 2017)
Jerry Smith (Microsoft Corporation) (Until September 2017)
Adrian Bateman (Microsoft Corporation) (Until May 2014)


This specification defines the stream formats for use with the Encrypted Media Extensions [ENCRYPTED-MEDIA].

Status of This Document

This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at https://www.w3.org/TR/.

This document was published by the Media Working Group as an Editor's Draft.

Comments regarding this document are welcome. Please send them to public-media-wg@w3.org (archives).

Publication as an Editor's Draft does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.

This document was produced by a group operating under the W3C Patent Policy. W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.

This document is governed by the 1 March 2019 W3C Process Document.

1. Purpose

This registry is intended to enhance interoperability among implementations and users of encrypted media streams with the Encrypted Media Extensions (EME) specification [ENCRYPTED-MEDIA]. In particular, this registry provides the means (1) to identify and avoid collisions among content type strings, and (2) to disclose information about encrypted data formats accepted by EME implementations to promote interoperability.

2. Organization

The registry maintains a mapping between content type strings and encryption format specifications, which describe the structure, semantics, and processing of the formats. The strings are those used for the media type/subtype pairs in contentType values provided to Encrypted Media Extensions [ENCRYPTED-MEDIA] APIs.

This registry is not intended to include any information on whether a 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 stream format.

3. Registration Entry Requirements

  1. Each entry must include a unique Initialization Data Type string.

  2. Each entry must include a link that references a publicly 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).

  3. Candidate entries must be announced on public-media-wg@w3.org(subscribe, archives) so they can be discussed and evaluated for compliance before being added to the registry.

  4. Per the Encrypted Media Extensions specification, the media container for a stream format MUST NOT be encrypted.

  5. Per the Encrypted Media Extensions specification, entries MUST be fully specified and support "common encryption" such that the content can decrypted in a fully specified and compatible way when a key or keys are provided.

4. Registry

MIME type/subtype Public Specification(s)
ISO Common Encryption ('cenc') Protection Scheme for ISO Base Media File Format Stream Format [EME-STREAM-MP4]
WebM Stream Format [EME-STREAM-WEBM]

A. References

A.1 Normative references

ISO Common Encryption ('cenc') Protection Scheme for ISO Base Media File Format Stream Format. David Dorwin; Adrian Bateman; Mark Watson; Jerry Smith. W3C. URL: ../stream/mp4.html
WebM Stream Format. David Dorwin; Adrian Bateman; Mark Watson. W3C. URL: ../stream/webm.html
Encrypted Media Extensions. David Dorwin; Jerry Smith; Mark Watson; Adrian Bateman. W3C. 18 September 2017. W3C Recommendation. URL: https://www.w3.org/TR/encrypted-media/