# Change Request Summary: Corrections to CMCD Phase 1

## CR Metadata
- **CR Number**: 0104
- **Specification**: TS 26.512 v19.1.0
- **Category**: F (Correction)
- **Release**: Rel-19
- **Work Item**: AMD_PRO-MED (Advanced Media Distribution for Professional Media)

## Reason for Change

MPEG-DASH 6th edition contains an ambiguity regarding the interpretation of service location and adaptation set based filtering. After consultation with client implementers, it was identified that the interpretation in 5G Media Streaming does not align with actual implementations. The issue relates to whether the filtering restrictions apply to the requests themselves or to the reporting of CMCD data.

## Summary of Technical Changes

The CR clarifies that the restrictions specified in the CMCD configuration apply to **which requests include CMCD information**, not to which CMCD data is reported. This is a critical distinction for proper implementation of the CMCD (Common Media Client Data) feature.

## Detailed Technical Modifications

### Clause G.5.2.2 - DASH Content Offering Requirements and Recommendations

**Key Change**: Modified the description of filtering capabilities to clarify scope.

- **Original text**: "The ability to restrict the subset of Service Locations, Adaptations Sets and/or media object types for which CMCD information is reported."

- **Corrected text**: "The ability to restrict the subset of requests for Service Locations, Adaptations Sets and/or media object types that include CMCD information."

This change emphasizes that the filtering controls **which HTTP requests carry CMCD data**, rather than controlling what data is reported once CMCD is included.

### Clause G.5.2.4 - Examples (Informative)

**Key Changes**: Updated the example description and XML comments to align with the corrected interpretation.

1. **Bullet point corrections**:
   - Changed "Reporting is restricted to a single service location" → "Reporting is restricted to requests for either dist1 or dist2"
   - Changed "Reporting is restricted to Segments assigned to video Adaptations Sets only" → "Reporting is restricted to requests for Segments assigned to video Adaptations Sets only"
   - Changed "Reporting is restricted to Media segments" → "Reporting is restricted to Media Segments" (also fixed capitalization)

2. **XML example**: The actual MPD XML structure remains unchanged, but the descriptive text now correctly explains that the `serviceLocations` and `adaptationSets` attributes in the `ClientDataReporting` element control which requests include CMCD headers, not which data is reported.

## Impact

### If Not Approved
- Inconsistent implementations across different client implementations
- Potential interoperability issues between 5GMS clients and application servers
- Misalignment with MPEG-DASH 6th edition implementer interpretations

### Affected Specifications
- Only TS 26.512 is affected
- No impact on other core specifications, test specifications, or O&M specifications

## Technical Context

This correction is part of the CMCD Phase 1 implementation in 5G Media Streaming. CMCD allows DASH clients to convey media-specific information to the CDN/application server to enable better delivery optimization. The filtering mechanism allows content providers to control the overhead of CMCD reporting by limiting which requests carry this additional metadata.