Network Working Group H. Alvestrand
Internet-Draft A. Grange
Intended status: Informational Google
Expires: August 29, 2013 February 25, 2013
VP8 as RTCWEB Mandatory to Implement
draft-alvestrand-rtcweb-vp8-01
Abstract
This document recommends that the RTCWEB working group choose the VP8
specification as a mandatory to implement video codec for RTCWEB
implementations.
This document is not intended for publication as an RFC.
Requirements Language
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].
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on August 29, 2013.
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Provisions Relating to IETF Documents
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements for an MTI codec . . . . . . . . . . . . . . . . . 3
3. Definition of VP8 . . . . . . . . . . . . . . . . . . . . . . . 3
4. Image quality evaluations . . . . . . . . . . . . . . . . . . . 3
5. Performance evaluation . . . . . . . . . . . . . . . . . . . . 4
5.1. Software . . . . . . . . . . . . . . . . . . . . . . . . . 4
5.2. Hardware support . . . . . . . . . . . . . . . . . . . . . 4
5.3. Hardware performance . . . . . . . . . . . . . . . . . . . 5
6. IPR status . . . . . . . . . . . . . . . . . . . . . . . . . . 5
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
8. Security Considerations . . . . . . . . . . . . . . . . . . . . 6
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
10.1. Normative References . . . . . . . . . . . . . . . . . . . 6
10.2. Informative References . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7
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1. Introduction
As described in [I-D.ietf-rtcweb-overview], successful interoperable
deployment of RTCWEB requires that implementations share a video
codec. Not requiring a video codec will mean that this decision is
left to processes outside the standards process, and risks the
spectre of fragmented deployment.
This memo argues that VP8 should be that codec.
2. Requirements for an MTI codec
As outlined by the presentation given at the IETF meeting at IETF 84
in Vancouver, it is unclear what the hard requirements for a video
codec are, but the items that it was suggested that proposals give
information on were:
o Image quality - comparative data was sought, but without defining
a baseline
o Performance - what resolutions / frame rates can be achieved in
software on some common systems
o Power consumption of hardware and/or software implementations
o Hardware support
o IPR status
This document lays out the available information in each category.
3. Definition of VP8
VP8 is defined in [RFC6386], and its RTP payload is defined in
[I-D.ietf-payload-vp8] . There are no profiles; all decoders are
able to decode all valid media streams.
4. Image quality evaluations
In tests carried out by Google on a set of ten sample video clips
containing typical video-conference content, VP8 outperformed the
x264 H.264 codec running the constrained baseline profile by on
average 37.2%. That is, at the same quality, measured by PSNR, VP8
produced 37.2% fewer bits on average than H.264. VP8 outperformed
H.264 on all ten of the test clips by between 19% and 64%. Both
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codecs were configured in one-pass mode using settings conducive to
real-time operation, and the ten clips varied in size between 640x360
pixels and 1280x720 pixels.
An independent evaluation by Christian Feller and Mohammed Raad,
presented to ISO/IEC SC29 WG11 in July 2012, showed that VP8
performed better than the (H.264 baseline) anchors for the IVC
project on a majority of the cases.
As part of the process of submitting VP8 for evaluation in ISO/IEC
JTC1 SC29 WG11 (MPEG), Google is also commissioning an independent
subjective quality evaluation effort.
5. Performance evaluation
5.1. Software
The current reference implementation is libvpx, developed in the WebM
project.
The encoding speed in software depends on the quality setting. On a
stock PC platform using an Intel Xeon CPU at 2.67 GHz, in a test
using extremely difficult 720p material and encoding at a target data
rate of 2 Mbit/sec, VP8's encoding speed varied from 48.4 fps (at the
setting used in WebRTC today) to 96.2 fps (at the fastest setting),
using a single thread. This variation in encode speed is achieved by
changing the configuration of VP8 encoding tools in a deterministic
way to trade-off encoding speed with output quality.
On a stock PC platform using an Intel Xeon CPU with 8 cores at
2.27GHz, tests using difficult 720p material encoded at 2 Mbit/sec
show that using a single thread VP8 can decode at 200.50 fps (in
comparison H.264, baseline profile, achieves 107.95 fps), using four
threads VP8 decodes at 519.96 fps (H.264 achieves 363.73 fps), and
using sixteen threads VP8 decodes at 1,076.49 fps (H.264 achieves
807.11 fps). .
5.2. Hardware support
To date, Google has licensed VP8 hardware accelerators to over 50
chip manufacturers, and VP8 hardware IP cores have also been made
available by Imagination Technologies, Verisilicon and Chips & Media.
Furthermore, Google is aware of several 3rd party implementations of
VP8 decoders and encoders from the world's leading semiconductor
companies.
At the time of this writing, more than a dozen of chip manufacturers
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have announced chips with 1080p VP8 support, including Samsung
(Exynos 5), NVIDIA (Tegra 3), Marvell (Armada 1500), Broadcom
(BCM28150), Texas Instruments (OMAP54xx), Freescale (i.MX 6), ST-
Ericsson (NovaThor L9540), LG Electronics, Hisilicon (K3v2), Rockchip
(RK2918, RK3066), Nufront (NS115), Ziilabs (ZMS40) and Allwinner
(A10). Google estimates that a clear majority of leading mobile
chipsets in 2013 will contain VP8 hardware support.
The encoder chip produced by Quanta has allowed OEMs to integrate
hardware HD VP8 encoding into their video camera hardware; this chip
is available now. More suppliers have such a chip coming.
5.3. Hardware performance
Several of the aforementioned hardware implementations are based on
the WebM video hardware designs described at
http://www.webmproject.org/hardware/. Performance figures include:
o Decode of 1080p video at 30 fps at less than 100 MHz clock
frequency
o Decoding more than ten simultaneous SD video streams on a single
chip
o Less than 25 milliwatts of power for 1080p decoding
o Encoding 1080p video at 30 fps at less than 220 MHz clock
frequency
o Less than 80 milliwatts of power for HD video encoding
Based on the Hantro G1 multiformat decoder implementation, the VP8
hardware decoder is 45% smaller in silicon area than the H.264 High
Profile decoder. VP8 also requires 18% less DRAM bandwidth than
H.264 as it does not use bidirectional inter prediction, allowing
significant reductions in the overall decoding system power
consumption.
6. IPR status
Google has made its position clear with respect to Google-owned IPR
in its licensing terms,
http://www.webmproject.org/license/additional/.
As of this moment (October 5, 2012), Google's royalty-free license
commitment is the only IPR statement filed against RFC 6386 in the
IETF disclosures database.
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Google has also submitted VP8 for consideration in ISO/IEC JTC1 SC29
WG11 (MPEG), in the IVC project (which aims for a royalty-free
codec), and expects ISO to execute its ordinary process for
resolution of IPR issues.
7. IANA Considerations
This document makes no request of IANA.
Note to RFC Editor: this section may be removed on publication as an
RFC.
8. Security Considerations
Codec definitions do not in themselves comprise security risks, as
long as there is no means of embedding active content in their
datastream. VP8 does not contain such active content.
Codec implementations have frequently been the cause of security
concerns. The reference implementation of VP8 has been extensively
tested by Google security experts, and is believed to be free from
exploitable vulnerabilities. There is a continuous program in place
to ensure that any vulnerabilities identified are repaired as quickly
as possible.
9. Acknowledgements
Several members of the Google VP8 team contributed to this memo.
10. References
10.1. Normative References
[I-D.ietf-payload-vp8]
Westin, P., Lundin, H., Glover, M., Uberti, J., and F.
Galligan, "RTP Payload Format for VP8 Video",
draft-ietf-payload-vp8-08 (work in progress),
January 2013.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC6386] Bankoski, J., Koleszar, J., Quillio, L., Salonen, J.,
Wilkins, P., and Y. Xu, "VP8 Data Format and Decoding
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Guide", RFC 6386, November 2011.
10.2. Informative References
[I-D.ietf-rtcweb-overview]
Alvestrand, H., "Overview: Real Time Protocols for Brower-
based Applications", draft-ietf-rtcweb-overview-05 (work
in progress), December 2012.
Authors' Addresses
Harald Alvestrand
Google
Kungsbron 2
Stockholm, 11122
Sweden
Email: harald@alvestrand.no
Adrian Grange
Google
1950 Charleston Road
Mountain View, CA 94043
USA
Phone:
Fax:
Email: agrange@google.com
URI:
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