Network Working Group C. Bran Internet-Draft Plantronics Intended status: Standards Track C. Jennings Expires: May 1, 2012 Cisco October 29, 2011 WebRTC Codec and Media Processing Requirements draft-cbran-rtcweb-codec-01 Abstract This document outlines the codec and media processing requirements for WebRTC client application and endpoint devices. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. This document may not be modified, and derivative works of it may not be created, and it may not be published except as an Internet-Draft. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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Bran & Jennings Expires May 1, 2012 [Page 1] Internet-Draft Abbreviated-Title October 2011 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Codec Requirements . . . . . . . . . . . . . . . . . . . . . . 3 3.1. Audio Codec Requirements . . . . . . . . . . . . . . . . . 3 3.2. Video Codec Requirements . . . . . . . . . . . . . . . . . 3 4. WebRTC Client Requirements . . . . . . . . . . . . . . . . . . 4 5. Legacy VoIP Interoperability . . . . . . . . . . . . . . . . . 5 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 7. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5 9. Normative References . . . . . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6 Bran & Jennings Expires May 1, 2012 [Page 2] Internet-Draft Abbreviated-Title October 2011 1. Introduction An integral part of the success and adoption of the Web Real Time Communications (WebRTC) will be the voice and video interoperability between WebRTC applications. This specification will outline the media processing and codec requirements for WebRTC client implementations. 2. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. 3. Codec Requirements This section covers the audio and video codec requirements for WebRTC client applications. To ensure a baseline level of interoperability between WebRTC clients, a minimum set of required codecs are specified below. While this section specifies the codecs that will be mandated for all WebRTC client implementations, it leaves the question of supporting additional codecs to the will of the implementer. 3.1. Audio Codec Requirements WebRTC clients are REQUIRED to implement the following audio codecs. o PCMA/PCMU - 1 channel with a rate of 8000 Hz and a ptime of 20 - see section 4.5.14 of [RFC3551] o Telephone Event - [RFC4734] o Opus [draft-ietf-codec-opus] 3.2. Video Codec Requirements If the MPEG-LA issues an intent to offer H.264 baseline profile on a royalty free basis for use in browsers before March 15, 2012, then the REQUIRED video codecs will be H.264 baseline. If this does not happen by that the date, then the REQUIRED video codec will be VP8 [I-D.webm]. The following feature list applies to all required video codecs. Required video codecs: Bran & Jennings Expires May 1, 2012 [Page 3] Internet-Draft Abbreviated-Title October 2011 o MUST support at least 10 frames per second (fps) and SHOULD support 30 fps o If VP8, then MUST support a the bilinear and none reconstruction filters o OPTIONALLY offer support for additional color spaces o MUST support a minimum resolution of 320X240 o SHOULD support resolutions of 1280x720, 720x480, 1024x768, 800x600, 640x480, 640 x 360 , 320x240 4. WebRTC Client Requirements It is plausible that the dominant near to mid-term WebRTC usage model will be people using the interactive audio and video capabilities to communicate with each other via web browsers running on a notebook computer that has built-in microphone and speakers. The notebook-as- communication-device paradigm presents challenging echo cancellation and audio gain problems, the specific remedy of which will not be mandated here. However, while no specific algorithm or standard will be required by WebRTC compatible clients, functionality such as automatic gain control, echo cancellation, headset detection and passing call control events to connected devices will improve the user experience and should be implemented by the endpoint device. To address the problems outlined above, suitable implementations of the functionality listed below SHOULD be available within an RTC-Web endpoint device. o Automatic gain control o Ability to override automatic gain control to manually set gain o Auto-adjustments to gain control and echo cancellation algorithms based on if a headset or internal speakers/microphone is being used o Echo cancellation, including acoustic echo cancellation o Headset detection o Call control event notification to connected devices such as headsets Bran & Jennings Expires May 1, 2012 [Page 4] Internet-Draft Abbreviated-Title October 2011 5. Legacy VoIP Interoperability The codec requirements above will ensure, at a minimum, voice interoperability capabilities between WebRTC client applications and legacy phone systems. Video interoperability will be dependent upon the MPEG-LA decision regarding H.264 baseline. 6. IANA Considerations This document makes no request of IANA. Note to RFC Editor: this section may be removed on publication as an RFC. 7. Security Considerations The codec requirements have no additional security considerations other than those captured in [I-D.ekr-security-considerations-for-rtc-web]. 8. Acknowledgements This draft incorporates ideas and text from various other drafts. In particularly we would like to acknowledge, and say thanks for, work we incorporated from Harald Alvestrand. 9. Normative References [I-D.ekr-security-considerations-for-rtc-web] Rescorla, E., "Security Considerations for RTC-Web", May 2011. [I-D.webm] Google, Inc., "VP8 Data Format and Decoding Guide", July 2010. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3551] Schulzrinne, H. and S. Casner, "RTP Profile for Audio and Video Conferences with Minimal Control", STD 65, RFC 3551, July 2003. Bran & Jennings Expires May 1, 2012 [Page 5] Internet-Draft Abbreviated-Title October 2011 [RFC4734] Schulzrinne, H. and T. Taylor, "Definition of Events for Modem, Fax, and Text Telephony Signals", RFC 4734, December 2006. Authors' Addresses Cary Bran Plantronics 345 Encinial Street Santa Cruz, CA 95060 USA Phone: +1 206 661-2398 Email: cary.bran@plantronics.com Cullen Jennings Cisco 170 West Tasman Drive San Jose, CA 95134 USA Phone: +1 408 421-9990 Email: fluffy@cisco.com Bran & Jennings Expires May 1, 2012 [Page 6]