]> Akamai

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Web and Internet Transport Media Over QUIC moq moqt MSF CMAF This document updates MOQT Streaming Format by defining optional syntax and semantics for carrying CMAF-packaged media. About This Document The latest revision of this draft can be found at . Status information for this document may be found at . Discussion of this document takes place on the Media Over QUIC Working Group mailing list (), which is archived at . Subscribe at . Source for this draft and an issue tracker can be found at .

Introduction CMAF compliant MOQT Streaming Format (CMSF) is a media format designed to deliver CMAF and LOC compliant media content over MOQ Transport (MOQT) . CMSF extends MSF and retains all the scope, capabilities and features of MSF including the catalog format, timeline, ABR switching and LOC support. CMSF is targeted at real-time and interactive levels of live latency, as well as VOD content. This document describes version 1 of the CMSF streaming format.

MSF Extension All of the specifications, requirements, and terminology defined in apply to implementations of this extension unless explicitly noted otherwise in this document.

CMAF Packaging

Initialization headers A CMAF header is a sequence of CMAF constrained ISO BMFF boxes that do not reference any media samples, but are associated with a CMAF track and are necessary for initializing the decoding of the subsequent CMAF fragments. The header for a given MOQT Track MUST be added to the catalog by generating an initDataList entry with a "type" of "inline", a "data" value of the header encoded using and an "id" which is unique across the initDataList items. That "id" value is then inserted as the value of an "initRef" property in all tracks which use that header for initialization.

Switching sets and tracks This specification defines a direct mapping between CMAF Tracks ( Sect 3.2.1) and MOQT tracks ( Sect 2.3). CMAF switching sets are a set of one or more CMAF tracks (3.2.1), where each track is an alternative encoding of the same source content and are constrained to enable seamless track switching (3.3.9). Each CMAF track in a switching set MUST be transmitted as a separate MOQT Track. The catalog entry for each of these tracks in the switching set MUST carry a Alternate group (altGroup) key with a common value. The MOQT Group numbers within these switching set tracks MUST be media time-aligned. Mandating the track being media time-aligned requires that the presentation time of the first media sample contained within the first MOQT Object of each MOQT Group is identical.

Object Packaging The payload of each Object is subject to the following requirements:

• MUST contain at least one Movie Fragment Box (moof) followed by a Media Data Box (mdat). This is equivalent to requiring that each Object hold at least one CMAF Chunk. The Media Fragment Box (moof) MUST contain a Movie Fragment Header Box (mfhd) and Track Box (trak) with a Track ID (track_ID) matching a Track Box in the initialization fragment.
• MAY contain multiple successive CMAF Chunks.
• MUST contain a single track.

Group Packaging Each MOQT Group

• MUST begin with an Object containing a stream access point (SAP) type 1 or 2.
• MUST contain one or more contiguous independently coded sequences of media samples.
• The Group boundary MUST align with a CMAF Fragment boundary. CMAF Fragments and CMAF Chunks MUST NOT span Groups.

Catalog description

CMAF packaging type This specification extends the allowed packaging values defined in to include one new entry, as defined in Table 1 below:

Name	Value	Reference
CMAF	cmaf	This RFC

Every Track entry in a CMSF catalog carrying CMAF-packaged media data MUST declare a "packaging" type value of "cmaf".

Max SAP starting types This specification adds two track-level catalog fields, as defined in Table 2 below:

Field	Name	Definition
Max Group SAP starting type	maxGrpSapStartingType
Max Object SAP starting type	maxObjSapStartingType

Max Group SAP starting type Location: T Required: Optional JSON Type: Number A number indicating the maximum SAP type the MOQT Groups in the track start with.

Max Object SAP starting type Location: T Required: Optional JSON Type: Number A number indicating the maximum SAP type the MOQT Objects in the track start with.

Event Timelines

SAP Type timeline CMSF defines a special instance of an Event Timeline track, termed the SAP Type timeline track. Its purpose is to convey information about the distribution of Stream Access Point types and their associated Earlist Presentation Times. In the catalog, the SAP-type timeline track MUST include a 'packaging' value of 'eventtimeline" and MUST include an 'eventType' value of 'org.ietf.moq.cmsf.sap'. In the SAP Type timeline JSON payload:

• The index reference MUST be 'l' for Location
• The data field is a JSON Array containing two integers. The first integer defines SAP type with an allowed value of 0,1,2 or 3. The value 0 indicates that the Object does not start with an ISOBMFF stream access point. The value equal to 1, 2, or 3 indicates that the Object begins with a stream access point of SAP type 1, 2, or 3, respectively. When the Object is the first Object in the Group, the value MUST be equal to 1 or 2. The second integer defines the earliest media presentation timestamp, rounded to the nearest millisecond, of all media samples in the Object defined by the Location of that record.

SAP-type timeline track example This shows an example of 30-fps HEVC-encoded content, in which each 4s Group beings with SAP-type 2 (i.e., the first picture in the Group is an IDR picture, while there may be one or more pictures in the Group following the IDR picture in decoding order but preceding it in output order). After 2 seconds in each Group, there is a SAP-type 3, i.e., a CRA picture, which is associated with one or more Random Access Skipped Leading (RASL) pictures. A small buffer of frames (10 frames at 30 fps) is skipped/discarded (RASL pictures) when the streaming session starts from the SAP-type 3 location. In this example, the EPT is the presentation time of the first picture after the RASL pictures in decoding order; all pictures after the RASL pictures can be fully correctly decoded and are thus presentable when the streaming session starts from the SAP-type 3 location. Note that if the streaming session starts from the start of the Group, then these RASL pictures can be fully correctly decoded and are thus presentable.

Content Protection CMSF supports content protection using Common Encryption for CMAF-packaged media. This enables interoperability with existing DRM ecosystems by reusing the signaling model established by DASH and the DASH-IF Encryption and Content Protection (ECCP) guidelines . Content protection in CMSF differs from the encryption scheme defined in Section 4.3. While MSF defines an end-to-end encryption mechanism using MoQ Secure Objects for LOC-packaged content, CMSF uses ISO Common Encryption applied at the CMAF media layer. In CMSF, the media samples within CMAF chunks are encrypted as specified by , and the DRM signaling is carried in the catalog rather than in per-object headers. A key advantage of CENC-based content protection is that decryption can be delegated to a Content Decryption Module (CDM) operating at a deeper system level, potentially in hardware or a trusted execution environment. This enables robust content protection through commercial DRM systems such as Widevine, PlayReady, and FairPlay Streaming, where the decryption keys and decrypted media are handled within a secure pipeline that is not accessible to the application layer. This hardware-level protection is a requirement for high-value content distribution and is not achievable with application-layer encryption schemes alone.

Content Protection catalog fields Content protection information is signaled in the catalog at two levels: a root-level contentProtections array containing DRM system descriptions, and track-level references to those descriptions.

Content Protections Location: R Required: Optional JSON Type: Array A JSON array of Content Protection objects at the root level of the catalog. Each object describes a single DRM system configuration. Content protection information MUST NOT be duplicated at the track level; all tracks reference the root-level entries. Each Content Protection object contains the following fields:

Reference ID Location: CP Required: Required JSON Type: String A unique identifier for this content protection entry. Track entries reference this value via the contentProtectionRefIDs field.

Default KIDs Location: CP Required: Required JSON Type: Array of Strings An array of default Key IDs (KIDs) expressed as UUID strings in the format "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx". These correspond to the default_KID values defined in Section 5. When multiple KIDs are present, each identifies a key used to encrypt a different set of samples (e.g., separate keys for different track types).

Scheme Location: CP Required: Required JSON Type: String The Common Encryption protection scheme as defined in . Allowed values are:

Name	Value	Description
CENC	cenc	AES-CTR full sample and sub-sample encryption
CBCS	cbcs	AES-CBC pattern-based encryption with subsample

The RECOMMENDED scheme for CMSF is "cbcs" as it provides better compatibility with hardware decoders and aligns with DASH-IF ECCP recommendations .

DRM System Location: CP Required: Required JSON Type: Object An object describing the DRM system associated with this content protection entry. It contains the following fields:

System ID Location: DS Required: Required JSON Type: String The DRM System ID expressed as a UUID string. Well-known system IDs include:

DRM System	System ID
Widevine	edef8ba9-79d6-4ace-a3c8-27dcd51d21ed
PlayReady	9a04f079-9840-4286-ab92-e65be0885f95
FairPlay	94ce86fb-07ff-4f43-adb8-93d2fa968ca2
ClearKey	1077efec-c0b2-4d02-ace3-3c1e52e2fb4b

The ClearKey system ID follows the W3C EME specification and corresponds to the DASH-IF ECCP "Explicit Clear Key Content Protection" mechanism .

License URL Location: DS Required: Optional JSON Type: Object An object containing the URL of the license acquisition service. The object has the following fields:

• url (String, Required): The URL of the license server.
• type (String, Optional): The license protocol type (e.g., "EME-1.0").

Certificate URL Location: DS Required: Optional JSON Type: Object An object containing the URL of the DRM certificate service. This field is REQUIRED for DRM systems that require a server certificate (e.g., FairPlay Streaming). The object has the following fields:

• url (String, Required): The URL of the certificate server.
• type (String, Optional): The MIME type of the certificate resource (e.g., "application/pkcs7-mime", "application/x-x509-ca-cert"). This corresponds to the certType attribute defined in .

Authorization URL Location: DS Required: Optional JSON Type: Object An object containing the URL of an authorization service. The object has the following fields:

• url (String, Required): The URL of the authorization server.
• type (String, Optional): The authorization protocol type.

PSSH Location: DS Required: Optional JSON Type: String A Base64-encoded Protection System Specific Header (PSSH) box as defined in Section 8.1. The PSSH box contains DRM system-specific initialization data needed by the client to acquire a license. This field SHOULD be present for DRM systems that require PSSH data (e.g., Widevine, PlayReady).

Robustness Location: DS Required: Optional JSON Type: String A string indicating the minimum robustness level required by the DRM system. The interpretation of this value is DRM system-specific.

Content Protection Reference IDs Location: T Required: Optional JSON Type: Array of Strings An array of Reference ID strings (see ) identifying which content protection entries from the root-level contentProtections array apply to this track. When this field is present, the track content is encrypted using Common Encryption and the subscriber MUST acquire appropriate licenses before decryption. When this field is absent, the track content is not protected by Common Encryption.

Initialization data for protected tracks For protected CMAF tracks, the initialization data (carried in the catalog initDataList array (as defined in ) MUST include the Protection Scheme Information Box ('sinf') containing the Scheme Type Box ('schm') and Scheme Information Box ('schi') with the Track Encryption Box ('tenc') as specified in Section 6. This enables the subscriber to determine the encryption parameters (default_isProtected, default_Per_Sample_IV_Size, default_KID) from the initialization segment.

ClearKey content protection For testing and development scenarios, CMSF supports ClearKey content protection using the W3C EME ClearKey mechanism. ClearKey uses the Common System ID "1077efec-c0b2-4d02-ace3-3c1e52e2fb4b" and follows the DASH-IF ECCP Explicit Clear Key Content Protection (ECCP) model . When using ClearKey:

• The systemID MUST be set to "1077efec-c0b2-4d02-ace3-3c1e52e2fb4b".
• The laURL field SHOULD contain the URL of a ClearKey license server that implements the EME ClearKey protocol.
• The optional pssh field SHOULD contain a Base64-encoded PSSH box with version 1, the Common System ID, and the KID(s) in the KID list.

Catalog Examples The following section provides non-normative JSON examples of various catalogs compliant with this draft.

Simulcast video tracks - 3 alternate video qualities along with audio This example shows catalog for a media producer capable of sending 3 time-aligned video tracks for high definition, low definition and medium definition video qualities, along with an audio track.

DRM-protected video with audio This example shows a catalog for a single DRM-protected video track and an unprotected audio track. The video track is encrypted using CBCS and references three content protection entries: Widevine, PlayReady, and FairPlay.

ClearKey-protected video This example shows a catalog using ClearKey content protection following the ECCP model, suitable for testing and development.

Conventions and Definitions The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 when, and only when, they appear in all capitals, as shown here.

Security Considerations TODO Security

IANA Considerations This document has no IANA actions.

References Normative References Cisco Google Google Meta This document defines Media over QUIC Transport (MOQT), a publish/ subscribe protocol that runs over QUIC and WebTransport. MOQT leverages the features of these transports, such as streams, datagrams, priorities, and partial reliability. MOQT operates both point-to-point and through intermediate relays, enabling scalable low-latency delivery. Despite its name, MOQT is media agnostic and can be used for a wide range of use cases. Akamai Cisco This document specifies the MOQT Streaming Format, designed to operate on Media Over QUIC Transport. Cisco Cisco Microsoft This specification describes a Low Overhead Media Container (LOC) format for encoded and encrypted audio and video media data to be used primarily for interactive Media over QUIC Transport (MOQT). It may be used in the MOQT Streaming Format (MSF) specification, which defines a catalog format for publishers to declare and describe their LOC tracks and for subscribers to consume them. Examples are also provided for building media applications using LOC and MOQT. ISO This document describes the commonly used base 64, base 32, and base 16 encoding schemes. It also discusses the use of line-feeds in encoded data, use of padding in encoded data, use of non-alphabet characters in encoded data, use of different encoding alphabets, and canonical encodings. [STANDARDS-TRACK] ISO In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings. Informative References ISO DASH-IF

Acknowledgments TODO acknowledge.