Hi,

I have reviewed this document as part of the Operational directorate's ongoing effort to review all IETF documents being processed by the IESG. These comments were written with the intent of improving the operational aspects of the IETF drafts. Comments that are not addressed in last call may be included in AD reviews during the IESG review. Document editors and WG chairs should treat these comments just like any other last call comments.

This Standards Track document provides analysis for WebRTC applications to send and receive video across a network. It specifies the video processing that is required, as well as video codecs and their parameters. Notes, Issues that are related to transport of media streams across the network are out of scope and specified in draft-ietf-rtcweb-rtp-usage. This document is well written. I don't see any issues from the operations and management perspective. It is ready to be published.

I have some minor comments as follow:

It is better to use "Video Orientation" rather than "orientation", also this may be described in Terminology section.

Personally, I am not sure the 3rd paragraph of section 5 should appear in a published RFC. It looks like recommendation for WG, not implementors. Further advice may be needed from responsible AD, I guess.

There are several places, which is better to use normative words:

 - In the 2nd paragraph of section 3, the video scan pattern for video codecs is Y’CbCr 4:2:0". It is better to use "SHOULD be" to replace "is".

 - In the section 3.1, "implementors are encouraged to". It is better to use "RECOMMENDED" to replace "encourage".

 - In the last paragraph of section 5, "It is, of course, advisable to implement ..., and implementors are encouraged to do so." It is better to use "RECOMMENDED" to replace "advisable" and "encouraged".

 - In the 2nd paragraph of section 6, "Additionally, codecs may...". It should be "MAY".

 - In the last paragraph of section 6, "Encoders are encouraged to...". It is better to use "RECOMMENDED" to replace "encouraged".

Minor editorial comments:

In the 2nd paragraph of section 3, "For clarity, this the color space indicated...". Remove "this:. Later in this paragraph, "the video scan pattern for video codecs is Y’CbCr 4:2:0". It is better to have a reference for "Y’CbCr 4:2:0".

In the 2nd paragraph of section 4, those mentioned under "Screen Sourced Video," above. A cross-reference to section 3.2 should be given.

Best regards,

Sheng