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This specification defines the initialization data formats for use with the Encrypted Media Extensions [ENCRYPTED-MEDIA].
Some formats may be extracted from media data as defined in the Encrypted Media Extensions Stream Format Registry [EME-STREAM-REGISTRY]. All may be provided separately, such as via a manifest or other application data.
This registry is non-normative.
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This document was published by the Media Working Group as an Editor's Draft.
Publication as an Editor's Draft does not imply endorsement by W3C and its Members.
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 a work in progress.
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This document is governed by the 18 August 2025 W3C Process Document.
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 initialization data type strings, and (2) to disclose information about initialization data formats accepted by EME implementations to promote interoperability.
The registry maintains a mapping between initialization data type strings and format specifications, which describe the structure and semantics of initialization data.
The strings are those used for initDataType values provided by and to Encrypted Media Extensions [ENCRYPTED-MEDIA] APIs.
This registry is not intended to include any information on whether a 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 format.
| Initialization Data Type | Public Specification(s) |
|---|---|
| cenc | "cenc" Initialization Data Format [EME-INITDATA-CENC] |
| keyids | "keyids" Initialization Data Format [EME-INITDATA-KEYIDS] |
| webm | "webm" Initialization Data Format [EME-INITDATA-WEBM] |