# Proposed General Updates to Terms of Reference for SA4 Working Group

## Summary and Background

This document proposes general updates to the SA4 Working Group Terms of Reference (ToR) in preparation for 6G work. The proposal is separate from AI-related updates covered in S4-260xxx. The document is submitted for agreement at SA4 and subsequent approval at SA plenary in March 2026.

## Main Technical Contributions

### Scope of Responsibilities Updates

#### Codec Development Expansion
- **Broadened codec scope**: Updated language to include "codecs for speech, audio, video, graphics and other newly emerging media types" (previously more limited scope)
- **Enhanced media handling**: Added explicit mention of "transport and handling of such media including related session descriptions and storage formats"

#### Service Architecture Enhancements
- **Cloud and edge computing**: Explicit inclusion of "media-centric cloud and edge computing architectures" in the definition of streaming and real-time communication services
- **Media APIs**: Added "media APIs" and "media profiles" to the list of SA4 responsibilities
- **Session descriptions**: Formalized responsibility for session descriptions

#### Third-Party Services Support
- **New responsibility area**: Added explicit scope for supporting third-party media services and applications to benefit from 3GPP system functionalities
- **Network and client interfaces**: Defined responsibility for providing suitable network and client interfaces/APIs
- **Traffic characteristics**: Includes definition of traffic characteristics and QoE requirements for emerging services (particularly XR applications)

#### AI/ML Integration
- **AI/ML for multimedia**: Added explicit mention of "artificial intelligence (AI)/Machine Learning (ML) for multimedia" as part of SA4's service scope

### Sub-Working Group Structure

The document formalizes the structure of four SA4 Sub-Working Groups with detailed Terms of Reference:

#### Multimedia Broadcast Streaming (MBS) SWG
- **Core focus**: Integration of codecs, system and delivery aspects for download, streaming, and messaging services
- **Key responsibilities**: 
  - Content formats and delivery protocols for unicast, multicast, and broadcast streaming
  - Messaging services
  - Cloud and edge computing architectures
  - Media APIs
  - QoE and energy efficiency metrics reporting
  - Traffic characteristics definition

#### Real-Time Communication (RTC) SWG
- **Core focus**: Integration of codecs and system aspects for real-time communication services including multimedia telephony and XR communications
- **Key responsibilities**:
  - Content formats and delivery protocols for services with real-time constraints
  - Updates to cloud and edge computing architectures
  - Media APIs
  - QoE metrics reporting
  - Traffic characteristics for real-time services

#### Video SWG
- **Core focus**: Specification of codecs for video, graphics, images, and other visual media types including immersive formats
- **Key responsibilities**:
  - Visual quality evaluation and test methodology
  - Characterization of visual formats
  - QoE metrics definition
  - **AI/ML applications**: Explicit inclusion of AI/ML applied to multimedia scenarios
  - Neural network model formats
  - Model optimization and compression aspects

#### Audio SWG
- **Core focus**: Development and maintenance of specifications for speech/audio codecs and quality evaluation
- **Key responsibilities**:
  - Transport and media handling aspects
  - Testing, verification, characterization, and selection criteria
  - End-to-end performance including terminal characteristics
  - Immersive audio formats for multimedia telephony and XR communications
  - Capture and rendering aspects of audio media delivery
  - **Ultra-low bitrate coding**: Explicitly added to support voice services via non-terrestrial networks (NTN)

### Governance and Decision-Making
- **Hierarchical structure**: Formalized that SA4 SWGs operate under SA4 WG
- **Decision confirmation**: All SWG documents require confirmation at SA4 level

### External Collaboration
The annex lists key external organizations for coordination:
- ISO/IEC JTC 1/SC 29
- SVT, DASH-IF
- 5G-MAG
- Khronos
- GSMA
- IETF
- ITU-T Study Groups 12 and 16

## Key Changes Summary

The main updates reflect:
1. Preparation for 6G work
2. Formalization of cloud/edge computing architectures
3. Explicit AI/ML integration (with detailed AI proposal in separate document)
4. Enhanced support for third-party services
5. Formalization of four SWG structure with detailed ToRs
6. Addition of ultra-low bitrate coding for NTN support
7. Strengthened focus on emerging media types and XR services