[Sframe] Magnus Westerlund's Block on charter-ietf-sframe-00-00: (with BLOCK and COMMENT)
Magnus Westerlund via Datatracker <noreply@ietf.org> Mon, 07 September 2020 16:42 UTC
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Date: Mon, 07 Sep 2020 09:42:15 -0700
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Subject: [Sframe] Magnus Westerlund's Block on charter-ietf-sframe-00-00: (with BLOCK and COMMENT)
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Magnus Westerlund has entered the following ballot position for charter-ietf-sframe-00-00: Block When responding, please keep the subject line intact and reply to all email addresses included in the To and CC lines. (Feel free to cut this introductory paragraph, however.) The document, along with other ballot positions, can be found here: https://datatracker.ietf.org/doc/charter-ietf-sframe/ ---------------------------------------------------------------------- BLOCK: ---------------------------------------------------------------------- I know we have had discussion touching on this before. But post vacation and looking on this charter again I think we need to have some additional discussion of the goals and how the charter describes them in relation to encoder sub-streams and identification of what is encapsulated. In regards to the below: This working group will not specify the signaling required to configure SFrame encryption. In particular, considerations related to SIP or SDP are out of scope. This is because SFrame is intended to be applied as an additional layer on top of the base levels of protection that these protocols provide. This working group will, however, define how SFrame interacts with RTP (e.g., with regard to packetization, depacketization, and recovery algorithms) to ensure that it can be used in environments such as WebRTC. I think there exist a conflict in the above paragraph in relation to stated goals of the work. With the following earlier sentence: " It may also be desirable to encrypt units of intermediate size (e.g., H.264 NALUs or AV1 OBUs) to allow partial frames to be usable." in mind creating an RTP payload format that is capable of carrying SFRAMEs that contains these units will require some interaction with the signalling. Even without these sub-stream SFRAMEs there exist a description capability that needs to exist in an RTP payload format for the end-consumer to correctly be able to route the protected data after decapsulation and that the end-point having that capability. If the goal here when it comes to RTP is simply to be able to treat SFRAME as CODEC in WebRTC and thus use WebRTC InsertableStreams as a receiver of the decrypted media ADUs. Require the use of the WebRTC application to have a proprietary signalling to know what this ADU is and then route it to a media decoder? I can see that working in the WebRTC only context. However, I would prefer if some thought was spent on at least having a model for what information may be needed to be able to handle the media streams. Considering RFC 7656 (https://datatracker.ietf.org/doc/rfc7656/) and the work that was needed for us to up-level how RTP worked and even discuss this so that we understood each other. I think SFRAME needs to discuss how it is going to handle identification of the data encapsulated by SFRAMEs for media. A single media source can be encoded in multiple formats. Each format may produce one or more sub-streams of encoding for scalability or robustness and this needs to conveyed. So looking at the above challenges in the context of SFRAME over RTP. So a possibility here is to say that the SSRC represents either just a media source. The RTP payload format provides only fragmentation of the SFRAME across multiple RTP packets and the RTP timestamp can be used to indicate its belonging in the timeline of the encoding. That puts a lot of the identification on the SFRAME layer, but its minimizes the signalling interactions related to RTP. However it creates limitation about what the SFU can do, especially when it comes to repair. Switching can be done based on Frame-marker extension header. However, layer related loss detection becomes impossible without additional information, or use of multiple SSRCs. Thus, I think the charter as currently written are uncertain if it can be executed on with stated goals. ---------------------------------------------------------------------- COMMENT: ---------------------------------------------------------------------- * Information to form a unique nonce within the scope of the key Is this really "Information to form a" the best formulation. I am uncertain if the goal is to have a specification for how to generate unique Nonce values within the context of a particular key, or if it is related to which information sources that should be used when creating a nonce?
- [Sframe] Magnus Westerlund's Block on charter-iet… Magnus Westerlund via Datatracker
- Re: [Sframe] Magnus Westerlund's Block on charter… Richard Barnes
- Re: [Sframe] [dispatch] Magnus Westerlund's Block… westhawk
- Re: [Sframe] Magnus Westerlund's Block on charter… Magnus Westerlund
- Re: [Sframe] Magnus Westerlund's Block on charter… Sergio Garcia Murillo
- Re: [Sframe] Magnus Westerlund's Block on charter… Magnus Westerlund
- Re: [Sframe] Magnus Westerlund's Block on charter… Magnus Westerlund
- Re: [Sframe] [dispatch] Magnus Westerlund's Block… Sergio Garcia Murillo
- Re: [Sframe] [dispatch] Magnus Westerlund's Block… Magnus Westerlund
- Re: [Sframe] [dispatch] Magnus Westerlund's Block… Sergio Garcia Murillo
- Re: [Sframe] [dispatch] Magnus Westerlund's Block… Magnus Westerlund
- Re: [Sframe] [dispatch] Magnus Westerlund's Block… Sergio Garcia Murillo
- Re: [Sframe] [dispatch] Magnus Westerlund's Block… Magnus Westerlund
- Re: [Sframe] [dispatch] Magnus Westerlund's Block… Sergio Garcia Murillo
- Re: [Sframe] [dispatch] Magnus Westerlund's Block… Bernard Aboba
- Re: [Sframe] [dispatch] Magnus Westerlund's Block… Sergio Garcia Murillo
- Re: [Sframe] [dispatch] Magnus Westerlund's Block… Magnus Westerlund
- Re: [Sframe] [dispatch] Magnus Westerlund's Block… Magnus Westerlund
- Re: [Sframe] [dispatch] Magnus Westerlund's Block… Emad Omara
- Re: [Sframe] [dispatch] Magnus Westerlund's Block… Magnus Westerlund
- Re: [Sframe] [dispatch] Magnus Westerlund's Block… Murray S. Kucherawy
- Re: [Sframe] [dispatch] Magnus Westerlund's Block… Emad Omara