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Network Working Group                                            G. Deen
Internet-Draft                                              NBCUniversal
Intended status: Informational                                 L. Daigle
Expires: January 1, 2017                    Thinking Cat Enterprises LLC
                                                           June 30, 2016

             Glass to Glass Internet Ecosysten Introduction


   This document introduces the Glass to Glass Internet Ecosystem
   (GGIE).  GGIE's purpose is to improve how the Internet is used create
   and consume video, both amateur and professional, reflecting that the
   line between amateur and professional video technology is
   increasingly blurred.  Glass to Glass refers to the entire video
   ecosystem, from the camera lens to the viewing screen.  As the name
   implies, GGIE's scope is the entire video ecosystem from capture,
   through the steps of editing, packaging, distributed and searching,
   and finally viewing.  GGIE is not a complete end to end architecture
   or solution, it provides foundational elements that can serve as
   building blocks for new Internet video innovation.

   This is a companion effort to the GGIE W3C Taskforce in the W3C Web
   and TV Interest Group.

   This document is being discussed on the ggie@ietf.org mailing list.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on January 1, 2017.

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Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Motivation: Video is filling up the pipes . . . . . . . . . .   4
   4.  Video is different  . . . . . . . . . . . . . . . . . . . . .   5
   5.  Historical Approaches to supporting Video on the Internet . .   6
     5.1.  Video as an application . . . . . . . . . . . . . . . . .   6
     5.2.  Video as a network problem  . . . . . . . . . . . . . . .   7
     5.3.  Video Ecosystem Encapsulation . . . . . . . . . . . . . .   7
   6.  Problem Statment and Solution Criteria  . . . . . . . . . . .   8
   7.  The Glass to Glass Internet Ecosystem: GGIE . . . . . . . . .   8
     7.1.  Related work:  W3C GGIE Taskforce . . . . . . . . . . . .   9
   8.  GGIE work of relevance to the IETF  . . . . . . . . . . . . .   9
     8.1.  Affected IETF work areas  . . . . . . . . . . . . . . . .   9
     8.2.  Example use cases . . . . . . . . . . . . . . . . . . . .   9
     8.3.  Core GGIE elements  . . . . . . . . . . . . . . . . . . .  11
   9.  Conclusion and Next Steps . . . . . . . . . . . . . . . . . .  15
   10. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  15
   11. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  15
   12. Security Considerations . . . . . . . . . . . . . . . . . . .  15
   13. Normative References  . . . . . . . . . . . . . . . . . . . .  15
   Appendix A.  Overview of the details of the video lifecycle . . .  15
     A.1.  Media Lifecycle . . . . . . . . . . . . . . . . . . . . .  16
     A.2.  Video is not like other Internet data . . . . . . . . . .  18
     A.3.  Video Transport . . . . . . . . . . . . . . . . . . . . .  20
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  20

1.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in [RFC2119].

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2.  Introduction

   In terms of shear bandwidth, the Internet's largest use, without any
   close second competitor, is video.  This is thanks to the
   proliferation of Internet connected devices capable of capturing and/
   or watching streamed video.  As of 2015 there are reports that
   YouTube users upload over 500 hours of video every minute, and that
   during evening hours NetFlix accounts for a staggering 50+% of
   Internet traffic.  The number of users using the Internet for both
   ends of the video create-view lifecycle grows daily worldwide, and
   this is creating an enormous strain on the underlying Internet
   infrastructure at nearly every point from the core to the edge.

   While video is one of the most conceptually simple uses of the
   Internet, it is perhaps one of the most complex technically, built
   from standards created by a large number of organizations and groups
   some dating from before the modern Internet even existed.  Many
   critical parts of this complex ecosystem were not created with either
   video's particular characteristics or vast scale of popularity in
   mind.  This has lead to both the degradation of the viewer experience
   and many Internet policy issues around access to bandwidth for video
   and the needed infrastructure to support the continued explosion in
   video transport on the Internet.

   The pace of video growth has faster been than new bandwidth for the
   past many years, and all indicators are that, instead of abating, it
   is actually accelerating as new users, new ways of sharing video, and
   new types of video continue to be added.  The Cisco Visual Networking
   Index an excellent source of detail on this subject.

   The combined current high levels of bandwidth consumed by video, plus
   the accelerating pace of video's growth mean that to meet users'
   demand for video, we must do more than simply relying on adding more
   bandwidth.  While other traditional improvements such as more
   efficient Codecs with better compression ratios are expected to
   contribute to keep video flowing on the Internet, many in the
   Internet video technology world have explored options to see if any
   new approaches could also be added to the mix to help the problem.
   That was the motivation behind the creation of the GGIE Taskforce
   within the W3C in 2014 with the charter to examine the end to end
   video ecosystem and identify new areas of opportunity to improve
   video's use of the Internet.

   The W3C GGIE taskforce explored ways that video uses the Internet and
   developed a series of use cases detailing specific scenarios ranging
   from video capture, the editing and production cycle, through to
   delivery to viewers.  Out of these use cases there emerged a
   recognition that there might be a new opportunity to improve Internet

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   video by enabling edge devices, and the underlying network to more
   actively participate in making delivery optimization choices beyond
   the simple ways the do currently.

   The GGIE approach is to apply and evolve existing technologies to the
   task of optimizing Internet video transport to permit applications,
   video devices, and the network to more actively participate in making
   smart access and transport decisions.  This approach recognizes that
   there are already extensively-deployed video infrastructure elements
   that need to continue to work and be part of the optimized video
   ecosystem.  These deployed devices, applications, players, and tools
   are responsible for the already high levels of video bandwidth
   consumption, and to only address new devices would not be solving the
   larger, most important problem.  This is why GGIE is an evolution of
   how video uses the Internet, and not a revolution involving wholesale
   replacement of existing architecture or protocols.

   GGIE is not a complete solution to the video problem.  It provides
   foundational building blocks that are intended to be used by
   innovators in their work to create new optimizations, and novel
   techniques to help address the video problem in the long term.

   GGIE initially proposes a simple framework of three components that
   will permit improved playback device identification of viewing
   sources and enable network level awareness of video transport and new
   cache selection chocies.  GGIE proposes: Using existing content
   identifiers as a means to identify a work, or title; Data level
   identifiers to identify the encoded video data for a particular
   manifestation of the title; A mapping service that permits bi-
   directional resolution of these identifiers.

   This document outlines the basic proposal for these three base GGIE
   components and introduces the overall GGIE approach to evolving the
   current video ecosystem by introducing basic standardized building
   blocks for innovators to build upon the Glass to Glass Internet

3.  Motivation: Video is filling up the pipes

   The growth in video bandwidth need is exceeding the growth in the
   bandwidth provisioning.  This trend is in fact accelerating, meaning
   the growth rate of video is growing faster than the growth rate of
   provisioning.  Traditional techniques of caching, higher efficiency
   codecs, etc, are all being used to help address the probiem and have
   helped the Internet to continue to support the growth of video thus

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   Video has been the top use of Internet bandwidth for several years
   and is larger than the bandwidth used by all other applications
   combined.  This trend is unlikely to ease or reverse itself as users
   of the Internet continue to make Internet transported video as one of
   their top uses of the Internet, either for uploading and sharing
   video they creator, or as a primary sources for viewing video to a
   wide variety of viewing devices: computers, tablets, phones,
   connected televisions, game consoles, and AV receivers.

   Adding to user demand, video itself is continually experiencing
   innovation introducing ever higher resolutions (SD, HD, 4K, 8K...),
   higher video quality, new distribution services (live one to many
   streaming), and new user uses.  The Cisco Visual Networking Index
   projects that by 2019 there will be nearly a million minutes of video
   per second transported by the Internet, a making up 80-90 percent of
   all IP traffic.

   The movitation behind GGIE is to help find new methods that can be
   brought to bear, in addition to all the exiting ones, to help manage
   the explosion in Internet video.

4.  Video is different

   Video is different than other data carried due to its extreme size of
   megabits per second, and gigebytes per hour of video, and when
   streamed for viewing its extreme sensitivity to latency and dropped
   packets.  This makes video unique amongst all other applications
   using the Internet for while some have latency and packet loss
   sensitivities they do not have exteme data sizes, and while others
   may have exteme data size they do not care about latency, time to
   retransmit lost packets, or in some cases loss of some individual
   packets at all.  A email user can tolerate an extra moment to
   retransmit dropped packets, and a web page user can tolerate a slow
   DNS lookup, but a video viewer sees both problems as jittery playback
   and as a failure of the network to meet their need.  (Audio has
   similar challenges in terms of intolerance of delay and jitter, but
   the data sizes are significantly smaller).

   Video data sizes continue to grow at roughly 4x per format iteration
   as cameras and playback devices are able to capture and display
   higher quality images.  Early digital video was often captured at
   either 320x240 pixel resolution or 640x480 standard definition
   resolution.  High definition or HD video at 1920x1080 became possible
   on some parts of the Internet after 2011, although even in 2016 it
   remains unavailable or unreliable through many connections such as
   DSL and many mobile networks.  Camera and player technologies are
   currently expanding again to permit 4K or 3840x2160 pixel resolution
   reflecting a 4x data increase over HD.

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   Streaming is very demanding, requiring consistent frame to frame
   playback in consistent constant time.  Advanced features such as
   pause, fast forward, rewind, slow motion, and fine scrubbing are
   considered by users as standard features in players that the network
   must support and serve to further the challenge facing the Internet.

   New video abilities such as live streaming by users (both one to one
   and one to many) bring what has traditionally been done by
   professional broadcasters with dedicated broadcast infrastructure
   into the realm of every day users with connected smartphones using
   the Internet as a realtime global broadcast infrastructure.

5.  Historical Approaches to supporting Video on the Internet

5.1.  Video as an application

   Internet video engineering began by adapting preexisting standards
   used for over the air broadcast (OTA) and physical media.  Video
   encodings, such as AVI and MPEG2, originally designed for playback
   from local storage connected to the player where added to the data
   types carried by existing protocols like HTTP, and new protocols such
   as RTSP and HLS.  Early use of the Internet for video was a copy-and-
   play model replacing the use of OTA broadcast and physical media to
   copy video between systems.

   As Internet bandwidth became sufficient to allow delivery of video
   data at the same rate it was being decoded, it became possible to
   stream video originally at very low resolutions such as 160x120
   pixels (19.2 kilopixels), eventually permitting standard definition
   (SD) 640x480 pixels (0.3 megapixels), and later high definition of
   1920x1080 pixels (2 gigapixels).  This trend continues with some
   providers beginning to offer 4K or 3840x2160 pixels (8.3 gigapixels)
   requiring very reliable and generous Internet bandwidth end to end
   connection between the viewer and source.

   Unlike the Web, email, and network file sharing which have been
   engineered and standardized in Internet focused organizations such as
   the W3C and IETF, video is dependent on standards developed by a very
   large number of groups, companies, and organizations which include
   the IETF, W3C but also MPEG, SMPTE, CEA, IEEE, ANSI, ISO, networking
   and technology companies, many others.  In contrast to the extensive
   end to end expert knowledge and engineering done to create the Web
   and email, Internet video has largely been an evolved cobbling and
   adaption exercise done by engineers with their focus on a few, or
   one, particular aspect or problem at a time, and little interaction
   between other parts of the Internet video ecosystem.  While it is
   very much possible to deliver video over the Internet, this
   uncoordinated cobbling has resulted in many areas of inefficiency

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   where engineering done from an end to end perspective could provide
   the opportunity to vastly improve how video uses the Internet, which
   offers the hope of improving the quality of video and increasing the
   amount of video which can be delivered.

5.2.  Video as a network problem

   Network, video, and application engineers have constructed elaborate
   solutions for dealing with bandwidth and processing limitations,
   network congestion, lossy transport protocols, and the ever growing
   size of video data.  These solutions commonly fall into one of
   several solution types:

   1.  Reducing data sizes through resolution changes, compression, and
       more efficient encodings

   2.  Downloading before playing instead of realtime streaming

   3.  Positioning the data close to the viewer via caches, typically on
       the network edge

   4.  Fetching of video data at a rate faster than playback

   5.  Transport protocols that attempt to deliver video data such that
       the data arrives as if it were done on a congestion free/lossless

   6.  Dynamic reselection of sources and transport routes on either a
       realtime or frequent intervals, 10-15 seconds, using player
       feedback mechanisms or network telemetry

5.3.  Video Ecosystem Encapsulation

   The current delivery ecosystem for video has been primarily developed
   at the higher application layers of the stack.  While there has been
   some video work done at lower levels such as general-purpose
   transport improvements, caching protocols in CDNi, various
   multicasting approaches, and other efforts, the majority of video-
   specific work has previously been done by groups such as ISO's Moving
   Pictures Expert Group (MPEG) which have focused on codecs and codec
   transport optimized for use on the Internet.  These efforts have made
   video possible on the Internet, but they have done so largely while
   treating the underlying network as a basic transporter of data.  This
   has resulted in little information being exposed to the network,
   information that could be used to optimize delivery of the video, and
   in an architecture that pushes more and more of the intelligence into
   an ever more complex and isolated core.

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   The current video model benefits from a significant amount of
   operational, feature, and protocol encapsulation that has come about
   due to different groups working independently on the components that
   make it up.  Like any system in which distinct pieces are well
   encapsulated from one another, this means it is possible to engage in
   improvements at the networking layer without the need to coordinate
   with higher levels of the video archicture.

6.  Problem Statment and Solution Criteria

   At its most basic the problem to be solved for video delivery is how
   to simultaneous maximize all of the following conditions: The number
   of viewing devices simultaneously supported by the network; The
   quality of video as measured by bit-rate and resolution; The number
   of distinct unique streams that can be delivered.

   Solution Contraints

   1.  Bandwidth growth alone is not a solution

   2.  Codec efficiency improvements alone are not a solution

   3.  Existing devices, infrastructure, video delivery techniques must
       as much as possible continue to be supported and benefit from new

7.  The Glass to Glass Internet Ecosystem: GGIE

   GGIE is an effort to improve video's use of the Internet by examining
   the end to end video ecosystem from the glass lens of the camera
   through to the glass the screen, and to identify areas of
   simplifications, standardization, and reengineering to make better
   use of bandwidth enabling smarter network use by video creators,
   distributors, and viewers.  GGIE is focused on how video uses the
   Internet, and not on how it is encoded or compressed.  Likewise GGIE
   does not deal with content protection.  GGIE's scope however does
   include creator and viewer privacy, content identifiction and
   recognition as a means to enable smarter network usage, edge caching,
   and discoverability.

   GGIE benefits from the encapsualtion of the video ecosystem elements
   enabling it to introduce evolutional features to elements without
   disrupting other district encapsulated parts.

   GGIE is intended to work with a wide variety of video encoding
   codecs, and video distribution and transport protocols.  While
   examples using MPEG-DASH are used due to is pervasive use, GGIE is

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   not limited to MPEG-DASH or any other video distribution system or

   Beyond improving the simple experience of a viewer using the Internet
   to watch linear video, it is hoped that a set of improved Internet
   video infrastructure standards will provide a foundation that permits
   innovators to create the next generation of Internet video content
   (such as multisource personalized composite experiences, interactive
   stories, and live personal broadcasting, to name a few).

   Due to the very diverse and large deployment of existing video
   playback devices and infrastructure, it is viewed as essential that
   any evolved ecosystem continues to work with the majority of the
   legacy deployment without the need for updates or changes to the
   exising ecosystem.

7.1.  Related work: W3C GGIE Taskforce

   A companion effort ran through 2015 in the W3C Web and TV Interest
   Group's GGIE Taskforce.  The W3C GGIE group developed a series of
   use-cases on discovery, search, delivery, identity, and metadata
   which can be found at https://www.w3.org/2011/webtv/wiki/GGIE_TF

8.  GGIE work of relevance to the IETF

   This section assumes a working familiarity with video creation and
   consumption "life cycle".  For reference, an overview has been
   provided in the Appendix.

8.1.  Affected IETF work areas

   It is expected that significant improvement is possible in the video
   transport ecosystem by modest evolution and adaption of existing
   standards for addressing, transporting, and routing of video data
   flows between sources and display.

8.2.  Example use cases

   The following example use case help illustrate the use of the GGIE
   core elements

8.2.1.  Alternate Source Discovery

   Description: A video player is streaming a movie from a CDN cache in
   the core of the network.  This use case illustrates the use of a
   media identifier to query a media address resolution service to
   locate additional alternate sources that offer the same movie.

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   1.  The video player user selects a movie to watch from a list using
       the player application UI.

   2.  The video player application has in the metadata description of
       the movie, the media identifier of the movie.  This identifier is
       passed to the playback device when the movie selected.

   3.  The playback device send a search query to the Media Address
       Resolution Service (MARS) which includes the media identifier,
       and additional query parameters use to filter the results

   4.  The MARS server searches its database and returns all the Media
       Encoding Networks matching the media identifier and filters the
       results using the additional parameters submitted in the query.
       Each Media Encoding Network represents a different encoding of
       the video.

   5.  The player then examines the returned list of media encoding
       networks and selects from it the best source of the title, from
       the perspective of the players on what is an optimal choice.

   6.  The player then directs its streaming requests to the selected
       Media Encoding Network addresses to obtain the video data for the

   7.  The video data is decoded and displayed on the screen

8.2.2.  Alternate Format Discovery

   Description: A video player is streaming a movie, and wants to send
   the audio to another device for playback.  However, the current video
   data being streamed does not contain any audio that matches the
   codecs the audio device can play.  The audio device uses the core
   GGIE services to locate an alternate encoding of the movie that
   contains audio it can decode.

   1.  The user directs the video player to send the audio portion of
       the playing video to an external audio device.

   2.  The video player obtains the media idenfitier for the video
       playing and passes it to the audio device.  It also passes the
       media encoded network address the video player is using.

   3.  The audio device begins streaming from the media encoding network
       is was given, but discovers the data does not include audio that
       is able to decode.

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   4.  The audio device sends a search query to the Media Address
       Resolution Service (MARS) which includes the media identifier,
       and additional query parameters including the list of audio
       codecs and language choice is able to decode.

   5.  The MARS server searches its database and returns all the Media
       Encoding Networks matching the media identifier and filters the
       results to only those matching the language and audio codec
       supplied in the search.

   6.  The audio player examines the returned list of media encoding
       networks and selects a media encoding network and begins
       streaming data from it.

   7.  The audo player decodes the returned movie data and plays it for
       the user.

8.3.  Core GGIE elements

   GGIE proposes three initial fundamental pieces:

   1.  Media Identifiers which identify the video at the title, or work

   2.  Media Encoded Networks which are subnets used to reference the
       encoded video data;

   3.  Media Address Resolution Service which maps Media Identifiers for
       a title to the Media Encoded Networks containing the encoded
       video versions of the title.

   These three foundational elements help by exposing information that
   can be used in selection in a way that is independement of the video
   encoding and video data storage choice.  It also enables more
   sophisiticated video use cases beyond the basic single device playing
   a video stream from an origin server over a flow controlled protocol.

8.3.1.  Media Identifiers

   A Media Identifier is a URI that carries a content identifier system
   declaration, and a content identifier from the system that refers
   unambiguously to a work, or title.  This maybe any contented
   idenfication system, GGIE does not specify the system used.

   For example, a media idenfier for a title identified by an EIDR value
   would include a declaration that the idenfitier is from EIDR, and
   would additionally contain the EIDR value.

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   At the application level, such as UI program quide applications,
   search engines, and metadata databases, it is the identification of
   the work or identity of the video that is of Interest typically, and
   not the encoding, bit-rate, or the location of CDN caches etc.  For
   example, a UI would indicate that "the Minions movie" as opposed to
   "a 15 megabit per second, HEVC encode with high dynamic range and
   Dolby encoded 7.1 english audio of the Minions movie".  Those
   additional technical details are important when choosing a particular
   encoded manifestation of the movie for delivery, decode, and
   playback, but they are not generally needed as information to be
   presented to the user or used to make viewing choices.  Such
   technical information is used after the user has chosen the title to
   watch, but are of use to the playback device not the user.  Media
   Identifiers in GGIE contain only title information, and not encoding

   There are many media identifiers in use for both personal and
   professional content, with new ones being introduced seemingly
   weekly.  To try to create a single identifier to either harmonize or
   replace the others has been proven repeatedly in practice to be an
   impossible task.  Recognizing this, the GGIE instead proposes the
   what is standardized is a URI which would contain at least two
   fields: 1) A scheme identifier; 2) An unambiguous title identifier
   (note: this is unambiguous only within domain of the identified

   For professional content, titles are increasingly identified with a
   scheme called EIDR that can identify both master versions of works,
   and edit level versions.  Likewise advertisments use a scheme called

8.3.2.  Media Address Resolution Service (MARS)

   The media address resolution service (MARS) provides bidirectional
   mapping of Media Identifiers to Media Encoding Networks.  It is
   queriable using a query protocol which returns any results matching
   the terms of the query parameters.

   A Media Identifier alone isn't sufficient to connect a device to a
   video data source.  The media identifier distinguishes the work, but
   not the technical details of an instance of the work such as codec,
   bit-rate, resolution, high dynanmic range video, audio encoding, nor
   does it include information about avaiable streaming sources etc.
   The Media Address Resolution Service (MARS) provides this
   association.  It can be queried with the Media Identfier, and
   optional filtering paramaters, and will return Media Encoding Network
   addresses for instances of matching encodings of the work.

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   This translation is used commonly in video streaming services today.
   The link provided in the program guide UI will include a unique
   identifier for the work which is then mapped by the streaing service
   backend into a URI contining a network identifier and other info
   which point to a caching server and the media data files in the
   cache.  MARS generalizes this and make it available via query over
   the network.

8.3.3.  Media Encoding Networks (MEN)

   Media Encoding Encoding Networks are arrangements of encoded video
   data that are assigned addresses under a shared prefix and subnet
   following a scheme appropriate for the encoding used by the video
   data.  Each Media Encoding Network instance represents a distinct
   instance of a set of associated encodings for a work.  Different
   Media Encoded Network address assignment schemes would be defined
   under GGIE to handle different encode data such as MPEG-DASH and HLS.

   For example, a single MEN instance would hold each of the differnt
   variable bit-rate encodes for a single encoding of a video If another
   new instance of the vide was prepared, it would have seperate
   distinct MEN assigned to it.  Example: Using Media Encoding Networks with MPEG-DASH

   A very basic form a video delivery uses persistent connection from a
   player to a video file source which then streams the video by
   transmitting the video file data, byte by byte in sequence, from the
   first byte of the file until the last.  This trivial approach
   requires the device to know the server IP address and port number to
   connect to.  Essentially this involved simply transporting the file
   from the source to the playback device in byte order.

   In practice simple file streaming is not used beyond local device to
   device playing in home networks as it doesn't permit dynamic bit rate
   selection, source or session fail over, or trick play (pause, skip
   forward, skip backward) etc.  Instead manifest files contain lists of
   available servers holding MPEG-DASH encodings of the larger video
   file into fragments containing short portions (e.g. 2-15 seconds) of
   the video called chunks by MPEG-DASH.  (GGIE generalizes the MPEG-
   DASH chunk term into the more general shards).  Each of shard is a
   distinct file typically named to reflects the video encode it belonds
   to, and it's sequence position.

   For example the shards for MY-VIDEO might be names MY-VIDEO-001, MY-
   VIDEO-002, ... MY-VIDEO-nnn.  The player then requests the shards in
   the order it wants them over a data transport protocol such as http,

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   with the translation of the actual data sent in response to requests
   for the named shards being handled by the data server.

   So under MPEG-DASH the player is sent a manifest file containing the
   address of the data server and the shard name to request.  The player
   then iterates over the available shards in the order desired by the
   user.  The manifest then contains URI's with the SERVER-ADDRESS and
   the CHUNK name.  This file can be sent once per video play, or more
   commonly is sent at an interval of ~15 seconds to permit the sending
   CDN to customize for each player, and to respond quickly to changes
   in the network delivery performance and availability.

   Each shard request by the device involves a network level server IP
   address and port number, and an application level shard name.  The
   network is thus able to manage the routing of request to the server,
   and the routing of the response, but it lacks the information needed
   to do anything else to help optimize the video data transport.

   GGIE proposes using Media Encoding Networks an evolution of this that
   has the benefit of being backwards compatible with manifest files,
   while enabling the transport network and video ecosystem to have more
   information to the network about the video transport flowing over it.

   Using Media Encoding Networks for MPEG-DASH will be described in
   another Internet-Draft, but the basic proposal is to assign the
   shards into a sequence of IP addresses organized to reflect the same
   ordering association that the chunk names followed in the MPEG-DASH
   scheme.  These shard addresses form a Media Encoding Network, and
   they expose to the network layer knowledge of the specific video data
   being transported between requesting device and the file server
   holding the data.

   This in practice means that Media Encoding Network addresses refer to
   the shard and not the server holding the shard.  This then permits
   the network to be involved in the routing of the request for the
   shard, as opposed to the CDN preparing the manifest file.  Among
   other benefits, this permits the network to provide path failover
   funcationality beyond the CDN manifest.

   This enables the network to be involved in shard source selection.
   Consider the use case wherein the network becomes aware of a local
   cache that holds the requested shard, and is closer to the device
   than another cache deeper in the network.  The network can direct the
   request to the local cache and save the transit cost and bandwidth of
   sending the request and response exchange with the deeper cache.
   This can reduce network congestion as well as deliver faster
   transport for the shard to the playback device.

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8.3.4.  Media Encoding Network Gateways

   In this new approach, the server providing the shard data is possibly
   better viewed as acting as a gateway to the shard addresses versus
   being just a file server.  In practical terms, existing CDN caches
   can perform this role by mapping the requested shard address to the
   on disk file containing the shard.  However, new CDN caches can be
   developed work directly with the Media Encoding Network scheme, and
   can act as smart caches proactively provisioning data within the
   Media Encoding Network address space.

9.  Conclusion and Next Steps

   GGIE seeks to held address this problem by establish standards based
   foundational building blocks that innovators can build upon creating
   smarter delivery and transport architectures instead of relying on
   raw bandwidth growth to satisfy video's growth.

   Next steps will include describing the working prototypes of the GGIE
   core elements and more exentise use cases addressed by GGIE many of
   which were defined in the W3C GGIE Taskforce.

10.  Acknowledgements

11.  IANA Considerations

   None (yet).

12.  Security Considerations

   None (yet).

13.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,

Appendix A.  Overview of the details of the video lifecycle

   This section outlines the details of the video lifecycle -- from
   creation to consumption -- including the key handholds for building
   applications and services around this complex data.  The section also
   provides more detail about the scope and requirements of video (scale
   of data, realtime requirements).

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   Note: this document only deals with streaming video as used by
   movies, TV shows, news broadcasts, sports events, music concert
   broadcasts, product videos, personal videos, etc.  It does not deal
   with video conferencing or WebRTC style video transport.

A.1.  Media Lifecycle

   The complex workflow of creating media and consuming it is
   decomposable into a series of distinct common phases.

A.1.1.  Capture

   The capture phase involves the original recording of the elements
   which will be edited together to make the final work.  Captured media
   elements can be static images, images with audio, audio only, video
   only, or video with audio.  In sophisticated capture scenarios more
   than one device maybe simulatneously recording.

A.1.1.1.  Capture Metadata

   The creation of metadata for the element, and for the final video
   begins at capture.  Typical basic capture metadata includes Camera
   ID, exposure, encoder, capture time, and capture format.  Some
   systems record GPS location data, assigned asset ids, assigned camera
   name, camera spatial location and orientation.

A.1.2.  Store

   The storage phase involves the transport and storage of captured
   elements data.  During the capture phase, an element is typically
   captured into memory in the capture device and is then stored onto
   persistent storage such as disc, SD or memory card.  Storage can
   involve network transport from the recording device to an external
   storage system using either storage over IP protocols such as iSCSI,
   a data transport such as FTP, or encapsulated data transport over a
   protocol such as HTTP.

   Storage systems can range from basic disk block storage, to
   sophisticated media asset libraries

A.1.2.1.  Storage Metadata

   Storage systems add to the metadata associated with media elements.
   For basic block storage, a file name, file size is typical, as is a
   hierarchical grouping, and creation date, last-access date.  For
   library system a identifier unique to the library is typical, a
   grouping by one or more attributes, a time stamp recording the
   addition to the library, and a last access time.

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A.1.3.  Edit

   Editing is the phase where one or more elements are combined and
   modified to create the final video work.  In the case of live
   streaming, the edit phase maybe bypassed.

A.1.4.  Package

   Packaging is the phase in which the work is encoded in one or more
   video and audio codecs.  These maybe produce multiple data files, or
   they may be combined into a single file container.  Typically it is
   in the packaging phase is the creation or registration of a unique
   work identifier for example an Entertainment Identifier from EIDR.

A.1.4.1.  Package Metadata

A.1.5.  Distribute

   The distribute phase is publishing or sharing the packaged work to
   viewers.  Often it is uploading it to a site such as YouTube, or
   Facebook for social media, or sending the packaged media to streaming
   sites such as Hulu.

   It is common for the distribution site to repackage the video often
   transcoding it to codecs and bitrates chosen by the distributor as
   more efficient for their needs.  Distribution of content expected to
   be widely viewed often includes prepositioning of the content on a
   CDN (Content Distribution Network).

   Distribution involves delivery of the video data to the viewer.

A.1.5.1.  Distribution Metadata

   Distribution often adds or changes considerable amounts of metadata.
   The distributor typically assigns a Content Identifier to the work,
   that is unique to the distributor and their content management system
   (CMS).  Additional actions by the distributor such as repacking and
   transcoding to new codecs or bitrates can require significant changes
   to the media metadata.

   A secondary use of distribution metadata is enabling easy discovery
   of the content either through a library catalog, EPG (electronic
   program guide), or search engine.  This phase often includes
   significant new metadata generation involving tagging the work by
   genre (sci-fi, drama, comedy), sub-genre (space opera, horror,
   fantasy), actors, director, release date, similar works, rating level
   (PG, PG-13), language level, etc.

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A.1.6.  Discovery

   The discovery phase is the precursor to viewing of the work.  It is
   where the viewer locates the work either through a library catalog, a
   playlist, an EPG, or a search.  The discover phase connects
   interested viewers with distribution sources.

A.1.6.1.  Discovery Metadata

   It is typical for discovery systems to parse media metadata to use
   the information as part of the discovery process.  Discovery systems
   may parse the content to extract imagery and audio as additional new
   metadata for the work to ease the viewers navigation of the discovery
   process perhaps as UI elements.  The system may import externally
   generated new metadata about the work and associate it in its search
   system, such as viewer reviews, metadata cross reference indices.

A.1.7.  Viewing

   The viewing phase encompasses the consumption of the work from the
   distributor.  For Internet delivered video it is typical for delivery
   to involve a CDN to perform the actual delivery.

A.2.  Video is not like other Internet data

   Video is distinctly different from other Internet data.  There are a
   number of characteristics that contribute to video's unique Internet
   needs.  The most significant characteristics are:

   1.  large size of video data ( Mbps to Gbps)

   2.  low latency demands of streamed video

   3.  responsiveness to trick play requests by the user (stop, fast
       forward, fast reverse, jump ahead, jump back)

   4.  multiplicity of formats and encodings/bit rates that are
       acceptable substitutes for one another

A.2.1.  Data Sizes

   Simply put compared to all other common Internet data sizes, video is
   huge.  A still image often ranges from 100KB to 10MB.  A video file
   can commonly range from 100MB to 50GB.  Encoding and compression
   options permit streaming videos using bandwidth ranging from 700Kbps
   for extremely compressed SD video, to 1.5-3.0 Mbps for SD video, to
   2.5-6.0 Mbps for HD video, and 11-30Mbps for 4K video.

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   Still images have 4 dimensional properties that affect their data

   1.  number of horizontal X pixels

   2.  number of vertical Y pixels

   3.  bytes per pixel

   4.  compression factor for the image encoding.

   Video adds to this:

   1.  frames per second playback rate

   2.  visual continuity between frames (meaning users notice when
       frames are skipped or played out of order)

   3.  discontinguous jumps between frames such as skipping forward or
       backwards to inserting frames from other sources between
       contigous frames (advertisement placement)

   Each video format roughly increases by x4 the data needs of the
   previously resolution: (1) SD is 640x480 pixels; (2) HD is 1920x1080
   pixels; (3) 4K is 3840x2160 pixels.

   Video, like still images, assigns a number of pixels to store color
   and luminance information.  This currently evolving alongside
   resolutions after being stagnant for many years.  The introduction of
   high dynamic range videos or HDR has changed the color gamut for
   video and increased the number of bits needed to carry luminance from
   8 to 10 and in some formats more.

   Compression is often misunderstood by viewers.  Compression does not
   change the video resolution, SD is still 640x480 pixels, HD is still
   1980x1080 pixels.  What changes is the quality of the detail in each
   frame, and between frames.  Compression algorithms work with the
   video images and movement to reduce data sizes through encoding of
   repetitive and

   Video is in its simplest form a series of still images shown
   sequentially over time, adding an additional attribute to manage.

A.2.2.  Low Latency Transport

   Viewers demand that video plays back without any stutter, skips, or
   pauses, which translates into low latency transport for the video

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A.2.3.  Multiplicity of Acceptable Formats

   One of the unique aspects of video viewing is that there can exist
   multiple different encodings/versions of the same video, many of
   which are acceptable substitutes for one another.  This is a unique
   aspect of video viewing and differentiates video delivery from other
   data transports.

   Other application data types don't have or leverage the concept of
   semantic equivalences to the same extent as video.  Even email, which
   supports multiple encodings in a multipart MIME message, has a finite
   number of representations of "the message", shipped as one unit,
   where as video often has many distinct different encodings each as
   seperate file or container of files managed as a distinct entity from
   the others.

A.3.  Video Transport

A.3.1.  File vs Stream

   There are two common ways of transporting video on the Internet: 1)
   File based; 2) Streaming.  File based transport can use any file
   transport protocol with FTP and BitTorrent being two popular choices.

   File based playback involves copying a file and then playing it.
   There are schemes which permit playing portions of the file while it
   progressively is copied, but these schemes involve moving the file
   from A->B then playing on B.  FTP and BitTorrent are examples of file
   copy protocols.

   Streaming playback is most similar to a traditional Cable or OTA
   viewing of a video.  The video is delivered from the streaming
   service to the playback device in real time enabling the the playback
   device to receive, decode, and display the video data in real time.
   Communication between the player and the source enable pausing, fast
   forward, rewind by managing the data blocks which are sent to the
   player device.

Authors' Addresses

   Glenn Deen

   Email: rgd.ietf@gmail.com

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   Leslie Daigle
   Thinking Cat Enterprises LLC

   Email: ldaigle@thinkingcat.com

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