Internet-Draft WARP Streaming Format January 2024
Law, et al. Expires 25 July 2024 [Page]
Media Over QUIC
Intended Status:
W. Law
L. Curley
V. Vasiliev
S. Nandakumar
K. Pugin

WARP Streaming Format


This document specifies the WARP Streaming Format, designed to operate on Media Over QUIC Transport.

About This Document

This note is to be removed before publishing as an RFC.

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This Internet-Draft will expire on 25 July 2024.

Table of Contents

1. Introduction

WARP Streaming Format (WARP) is a media format designed to deliver CMAF [CMAF] compliant media content over Media Over QUIC Transport (MOQT) [MoQTransport]. WARP works by fragmenting the bitstream into objects that can be independently transmitted. WARP leverages a simple prioritization strategy of assigning newer content a higher delivery order, allowing intermediaries to drop older data, and video over audio, in the face of congestion. Either complete Groups of Pictures (GOPS) [ISOBMFF] or individual frames are mapped to MoQTransport Objects. WARP is targeted at interactive levels of live latency.

This document describes version 1 of the streaming format.

2. 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 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

This document uses the conventions detailed in Section 1.3 of [RFC9000] when describing the binary encoding.

3. Media packaging

WARP delivers CMAF-packaged media bitstreams. This specification references [CMAFpackaging] to define how CMAF packaged bitstreams are mapped to [MoQTransport] groups and objects.

Both CMAF Object mappings [CMAFpackaging] Section 4 are supported and a content producer may use either. To identify to consumers which object mapping mode is being used for a given Track, a new track field is defined as per table 1.

Table 1
Field Name Required Location JSON type Definition
WARP packaging mode warp-packaging yes RT String See Section 3.1

3.1. Packaging mode

The packaging mode value is defined by Table 2.

Table 2
warp-packing field value Condition Explanation
frag-per-group [CMAFpackaging] 4.1 is active Each CMAF Fragment is placed in a single MOQT Object and there is one MOQT Object per MOQT Group
chunk-per-object [CMAFpackaging] 4.2 is active Each CMAF chunk is placed in a MOQT Object and there is one MOQT Group per CMAF Fragment

3.2. Time-alignment

WARP Tracks MAY be time-aligned. Those that are, are subject to the following requirements:

  • Time-aligned tracks MUST be advertised in the catalog as belonging to a common render group.

  • The presentation time of the first media sample contained within the first MOQT Object of each equally numbered MOQT Group MUST be identical.

A consequence of this restriction is that a WARP receiver SHOULD be able to cleanly switch between time-aligned media tracks at group boundaries.

3.3. Content protection and encryption

The catalog and media object payloads MAY be encrypted. Common Encryption [CENC] with 'cbcs' mode (AES CBC with pattern encryption) is the RECOMMENDED encryption method.

ToDo - details of how keys are exchanged and license servers signaled. May be best to extend catalog spec to allow the specification of content protection schema, along with any pssh or protection initialization data.

4. Catalog

WARP uses the Common Catalog Format {[COMMON-CATALOG-FORMAT}} to describe the content being produced by a publisher.

Per Sect 5.1 of [COMMON-CATALOG-FORMAT], WARP registers an entry in the "MoQ Streaming Format Type" table. The type value is 0x001, the name is "WARP Streaming Format" and the RFC is XXX.

Every WARP catalog MUST declare a streaming format type (See Sect 3.2.1 of [COMMON-CATALOG-FORMAT]) value of 1.

Every WARP catalog MUST declare a streaming format version (See Sect 3.2.1 of [COMMON-CATALOG-FORMAT]) corresponding to the version of this document.

The catalog track MUST have a track name of "catalog". A catalog object MAY be independent of other catalog objects or it MAY represent a delta update of a prior catalog object. The first catalog object published within a new group MUST be independent. A catalog object SHOULD only be published only when the availability of tracks changes.

Each catalog update MUST be mapped to a discreet moq-transport object.

5. Media transmission

The MOQT Groups and MOQT Objects need to be mapped to moq-transport Streams. Irrespective of the Section 3.1 in place, each MOQT Object MUST be mapped to a new moq-transport Stream.

6. Workflow

A WARP publisher MUST publish a catalog track object before publishing any media track objects.

At the completion of a session, a publisher MUST publish a catalog update that removes all currently active tracks. This action SHOULD be interpreted by receivers to mean that the publish session is complete.

7. Security Considerations


8. IANA Considerations

This document creates a new entry in the "MoQ Streaming Format" Registry (see [MoQTransport] Sect 8). The type value is 0x001, the name is "WARP Streaming Format" and the RFC is XXX.

9. Normative References

"International Organization for Standardization - Information technology - MPEG systems technologies - Part 7: Common encryption in ISO base media file format files", .
"Information technology -- Multimedia application format (MPEG-A) -- Part 19: Common media application format (CMAF) for segmented media", .
Law, W. and L. Curley, "CMAF Packaging for moq-transport", Work in Progress, Internet-Draft, draft-wilaw-moq-cmafpackaging-00, , <>.
"Common Catalog Format for moq-transport", , <>.
"Information technology -- Coding of audio-visual objects -- Part 12: ISO Base Media File Format", .
Curley, L., Pugin, K., Nandakumar, S., and V. Vasiliev, "Media over QUIC Transport", Work in Progress, Internet-Draft, draft-lcurley-moq-transport-00, , <>.
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <>.
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <>.
Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based Multiplexed and Secure Transport", RFC 9000, DOI 10.17487/RFC9000, , <>.


Authors' Addresses

Will Law
Luke Curley
Victor Vasiliev
Suhas Nandakumar
Kirill Pugin