IETF MOQ WG: Filters on SUBSCRIBE_TRACKS

Message Snapshot

• List: moq@ietf.org
• Thread subject: Filters on SUBSCRIBE_TRACKS
• Message subject: [Moq] Filters on SUBSCRIBE_TRACKS
• Author: Ian Swett
• Published: 2026-06-15T22:08:31.000Z
• Source tag: ietf-mailing-list
• Message URL: Open in IETF Mail Archive

Summary

Ian Swett posted to the MOQ working group mailing list on June 15, 2026. In the context of Top-N, at the interim I asked a question about filtering out Tracks known to be of no interest (e.g., tracks with no movement wh…

Why It Matters

This message came from the public MOQ working group archive and captures active discussion, meeting coordination, or implementation feedback around Media over QUIC.

Message Excerpt

In the context of Top-N, at the interim I asked a question about filtering out Tracks known to be of no interest (e.g., tracks with no movement when looking for tracks with the most movement, etc). I asked whether the

Plain-Text Body

In the context of Top-N, at the interim I asked a question about filtering out Tracks known to be of no interest (e.g., tracks with no movement when looking for tracks with the most movement, etc). I asked whether the proposed Track filters (PR #1518 https://github.com/moq-wg/moq-transport/pull/1518) solved this problem by allowing you to perform Top-N only across Tracks with a parameter above a certain threshold. In the room, it seemed like everyone thought it did. After thinking about it more, I'm not sure how it could, but let me walk through an example and let me know if I'm thinking about it wrong.

*Example: *I would like to do Top-10 for a Property (e.g., motion) like the scenario described during the interim, where the cameras are immediately connected to relays with <10 publishers each. Naively, that means a central relay would have to subscribe to every camera to construct a Top-10.

If one could filter out Tracks with no motion, that could dramatically reduce the amount of data, but if I put a property filter in SUBSCRIBE_TRACKS and it filters on Track Properties, then the Track property value for all camera Tracks might be no motion. If there was no value, I'm unsure what would happen, but let's ignore that for now. If motion occurs, I suddenly become interested in the Track, but if the Track was filtered out, I will never receive a PUBLISH and thus never see it. Alternatively, if filters are like other parameters on SUBSCRIBE_TRACKS, where they get copied over to the resulting PUBLISHes, then I get far too many subscriptions, but I can get only the Objects from Tracks with movement.

It feels like we need to specify (likely via separate params) whether the filters apply only to the Track Properties (which has clear use cases, e.g., "Only give me AV1 Tracks"), or if the filters are copied onto the resulting subscriptions. This is not an effort to move anything into or out of MoQT, just an effort to clarify how the filter functionality is intended to work with SUBSCRIBE_TRACKS.

Thanks, Ian