|
Options for Internet Video-on-demand at Dartmouth
A white paper by Jay Collier, Dartmouth Web Publishing
Services
Summary: A single Internet Video-on-demand
system that delivers a wide range of distribution options (from on-campus users
to alumni overseas) and access restrictions (from authorized groups to
unlimited viewing) does not exist. Until is does, multiple products and
services will have to be integrated, behind the scenes, to provide a seamless
experience for users (producers and consumers) throughout the lifecycle of each
digital media asset. Evaluations of seven options and recommendations for
further initiatives are included.
Note: Please read "Lost and
Found: A Primer to Digital Media Asset Management at Dartmouth" first; much
of the information in this paper assumes prior knowledge.
1. Context
Video-on-demand is one of the greater challenges for Web delivery.
Comprising a large amount of data in its raw form, broadcast-quality video
needs to be compressed and handled very efficiently in order to be viewed as a
dependable service by Internet users.
In its first generation, Web video was compressed with a variety of
proprietary compression methods (Cinepak, Sorenson) and contained within
proprietary wrappers (QuickTime, Real, Windows Media). The compressed
derivatives were low resolution, filled with artifacts, and couldn't be played
without interruption unless supported by a expansive system of servers located
around the Internet, close to users.
Ultimately, future Internet Video on Delivery (iVoD) delivery systems will
support standard formats and be integrated within the complete media asset
lifecycle, linking with external metadata from creation through to storage,
discovery, and delivery. Unfortunately, that level of integration is not yet
ubiquitious.
In this paper, we will evaluate tools and techniques for distributing iVoD:
broadcast-quality video assets created by faculty, staff, and students at
Dartmouth. We will not focus on the production of those assets — other than the
acquisition of metadata — but instead on their access and distribution, which
is the traditional focus of video-on-demand via CATV systems.
For an overview of packaging video assets into a single program stream on
the Web, see the Public
Webcast Discovery Project report.
2. The Framework
A. Lifecycle support
For this paper, we will define the media asset lifecycle as having five
phases: create, annotate, store, search, and distribute.
Figure 1. The Asset Lifecycle, Simplified
Some video-on-demand systems excel in multiple parts of the asset lifecycle
while others provide support for some areas. Few, however, cover the entire
cycle.
Again, see "Lost and
Found: A Primer to Digital Media Asset Management at Dartmouth" for a
deeper discussion about the asset lifecycle.
B. Distribution range and audience restrictions
Current restraints in Internet technology affect two aspects of iVoD video:
distribution range and audience restrictions. The result is that different
options have evolved for certain needs: whether the audience is on campus or
worldwide, and whether or not the asset needs to restricted to a selected group
of viewers.
Figure 2. Distribution Range
Distribution range includes local (on-campus course sessions) to distant
(video news releases for worldwide viewing). Fortunately, the on-campus network
environment provides a high level of control, so that a predetermined number of
on-demand video streams can be dependably delivered to concurrent users.
For robust off campus distribution, however, either a network of edge
servers or a peer-to-peer network is required to assure that sufficient storage
and bandwidth is available for delivery of the broadcast-quality video asset
without interruption.
Figure 3. Audience Restrictions
Audience restrictions can vary from closed (students in a single course) to
open (a worldwide alumni audience). Open, unrestricted usage is simple; it is
the default for most media players.
Restricted playback for pre-defined audiences, however, is a challenge,
especially since there are no widely-accepted open standards for doing so. Some
architectures have implemented robust digital restrictions management (DRM)
systems -such as Apple Fairplay and Microsoft Windows Media - but they
currently require accessing the asset with a specific player.
So, by integrating these three factors, we now have a model to help us make
a preliminary evaluation of various iVoD systems.
Figure 4. iVoD Evaluation Model
3. Context
At this time, there is no single, robust iVoD system that provides a full
distribution range with effective audience restrictions. Various solutions,
however, can be combined to cover primary needs until single open-standard
solutions becomes available.
For that reason, it makes sense to create a delivery master (a primary
"derivative") in a format with the greatest potential for preservation and
transcoding (or repurposing) and also to record external information about the
asset ("metadata") so that it can be repurposed in the future.
Then, when an Internet VoD system is selected for a particular function, two
processes need to be developed: an on-the-fly automated process for
transforming essence to an appropriate new version ("derivative") when
requested, and a system for the exchange of metadata between an asset
management system and the VoD delivery system.
Metadata is the most challenging piece of this puzzle. None of the iVoD
systems we've investigated have robust support for ingest of pre-defined XML
schemas, let alone exchange of that data via XML Web Services or defined API
protocols. This may change in the near future, but a set of schemas that serves
Dartmouth's general media asset management needs will go a long way toward
being ready when an optimal iVoD system becomes available.
Note that the Library of Congress, with Google and other partners, has
launched a World Digital
Library initiative. As its core, "the Library will develop a plan for
identifying technology issues related to digitization and organization of WDL
collections. These might include presentation, maintenance, standards and
metadata schemas that support both access and preservation."
4. Options
We will now evaluate seven Internet VoD solutions against these three
requirements: support for the full asset lifecycle, robust distribution support
for local and worldwide users, and flexible audience restrictions from small
groups to unlimited access. Each factor will be ranked from 1 (low) to 3 (high)
with preliminary rating based on the sum of those totals.
A. Akamai Edge Platform
Akamai was one of the first Internet video distribution networks and, as
such, is used by the major programming services that moved early into Internet
VoD, such as CNN, WGBH, etc.
A network of hundreds of "edge servers" — mirrored servers located at
physical locations around the internet — cache and deliver content when
requested by nearby users.
Akamai's Edge Platform does not provide an end user interface, only
distribution of the assets — streams and downloads — that can be integrated
into locally-hosted Web presentation applications. Interface and management of
user restrictions needs to be developed locally. Other Akamai services provide
wider support of the lifecycle.
Figure 5.
Pros
- Tested thoroughly through years of service.
- Powerful customization possible with local Web applications.
- Supports a wide variety of binary and text formats, including mp3;
architecture agnostic.
Cons
- No integrated digital rights management; external players and development
required.
- No integrated metadata search; external development required.
References
Preliminary rating
1 (lifecycle) + 1 (restrictions) + 3 (range) = 5 (total)
B. Brightcove
Brightcove is a new entry into the Internet VoD space and is currently in
prototype development. With funding from major media corporations, Brightcove
may find a combination of cross-platform support and strong digital restriction
management acceptable to the television and film industry.
The two layers of service provided are distribution (publisher features,
affiliate aggregation, consumer search and access) and monetization
(advertising, pay-per-view, syndication, licensing)
Pricing is primarily oriented toward paid media: based on commission. For
free media: pricing is based a combination of bandwidth plus stream
launches.
The Brightcove player supports Flash video codecs, but support for
MPEG-4-AVC playback, for example, an external player such as WindowsMedia or
QuickTime is required.
Figure 6.
Pros
- All interface elements are integrated in a proprietary Flash interface for
cross-platform support.
- Auto ingest is provided for essence, derivatives, metadata via batch
APIs.
- All metadata is accessible to external systems via APIs.
- HTML documents for each channel integrate text transcripts.
Cons
- All derivatives must be pre-compressed; no live transcoding available
(although expected in Q2/Q3 of next year).
- Support for limited compression formats.
- Full transcript search not available at launch.
- Lower accessibility of Flash interface (as compared to HTML) for screen
readers and other alternative interfaces.
Preliminary rating
3 (lifecycle) + 3 (restrictions) + 3 (range) = 9 (total, with an important
caveat: the service is not yet available)
C. DTV/Broadcast Machine
"The Participatory Culture Foundation, is a nonprofit organization that is
developing a TiVo-like combination RSS feed reader, Bittorrent client, and
video player to go with their Broadcast Machine video publishing package. The
goal is to put together a complete and OSS platform that lets nontechnical
producers broadcast their videos to nontechnical users without using lots of
bandwidth."
DTV is the player — currently for Mac with Windows and Linux in final
development — based on the VLC player, which supports a variety of streaming
and downloading formats. DTV presents channels published on individual Web
sites and aggregated, via RSS, in its channel guide as well as through other
videologging aggregators. DTV supports MPEG-4, MPEG-2, and QuickTime streaming
(RTSP).
Broadcast Machine is the set of scripts that can be posted in any
PHP-enabled Web account. It allows for the aggregation and syndication of live
or recorded videos (via URL or Torrent) via categories and tags, including
playlists. Channels can be restricted to pre-authorized users. (There is
currently no batch ingest of access information, but the system is open PHP, so
custom development would be minimal.
Broadcast Machine can syndicate public assets hosted in the OurMedia section
of the Internet Archive at no cost.
This project has received funding from Mitch Kapor. Partners include
Creative Commons and Current TV. Press coverage has included CNET, Wired,
Business Week,
The system is in a similar market space as Brightcove (corporate) and the
Open Media Network (public broadcasting).
Figure 7.
Pros
- All interface elements are integrated in a single application window
- DTV plays all compression formats supported by VLC
- Assets are identified by URL and so can live on any host (including QTSS,
Internet Archive, Video Furnace)
- All metadata is accessible to external systems via APIs.
Cons
- All derivatives must be pre-compressed; no live transcoding
available
- Use of uploaded transcript for search isn't clear
Preliminary rating
2 (lifecycle) + 2 (restrictions) + 3 (range) = 7
References
D. Flash Video Streaming Service
Flash Video wraps video encoded in the On2 format into a Flash .flv file.
That asset can then be distributed in several ways: integrated into a Flash
.swf skin, or streamed or downloaded as a .flv file from a Web server, a Flash
Server, or the Flash Video Streaming Service. A Creative-Commons licensed
player is available for download delivery.
In order to play Flash video consistently at a distance, delivery via an
edge server network is required. Three companies offer the service now. For
asset lifecycle support, however, an interface and management system needs to
be developed external to the player, which is exactly what Google Video and
Brightcove do.
Figure 8.
Pros
- Nearly ubiquitous player installation.
- Authentication available through VitalStream (tokens, IP Addresses,
referrers).
Cons
- Requires proprietary compression and wrapper formats.
- Complex user interface for producers only partially simplified in Flash
8.
- Lower accessibility of Flash interface.
- Management and interface must be delivered externally.
References
Preliminary rating
1 (lifecycle) + 1 (restrictions) + 3 (range) = 5 (total)
E. Google Video (Beta)
Google launched the beta version of this service last spring; after its
first past six months, thousands of independent videos are being hosted and
delivered for free.
Google uses Flash Video to deliver assets to the browser window.
Figure 9.
Pros
- Free.
- Support for wide portion of life cycle, including metadata (transcript)
search.
- Cross platform playback (via Flash).
- RSS feeds are in development for integration in external interfaces.
Cons
- Advertisements may be presented next to videos.
- Does not currently support .mp3 file playback.
References
Preliminary rating
2 (lifecycle) + 1 (restrictions) + 3 (range) = 6 (total)
F. Ourmedia.org/Internet Archive
Ourmedia.org is a free, "do-it-yourself mechanism that lets users anywhere
in the world upload material, view or share media (depending on the license),
rank their favorite works, and offer commentary and tutorials."
Ourmedia provide an interface to many digital file formats — video,
audio, photos, text and software — and acts as a front end for the Internet
Archive (IA). Ourmedia provides Mac and Windows applications that
streamline file upload; files are then posted on the free IA servers, and
distributed via the IA network.
Ourmedia is being co-led by Marc Canter, a recognized leader in social
networks and blogging. The online community service is powered by the
open-source Drupal community system. The Internet Archive "was
founded to build an Internet library, with the purpose of offering permanent
access for researchers, historians, and scholars to historical collections that
exist in digital format."
Of course, media can be posted directly to the Internet Archive, as a number
of schools have done, and accessed directly from there.
Figure 10.
Pros
- Highly-established archive storage.
- Simple, cross-platform upload tool.
- Supports a wide variety of binary and text formats, including mp3;
architecture agnostic.
Cons
- Desktop player required.
- No support for legal file sharing, such as BitTorrent, to reduce
distribution latency.
- No support for integrated digital rights management; external players and
development required.
References
Preliminary rating
3 (lifecycle) + 1 (restrictions) + 3 (range) = 7
(total)
G. QuickTime Streaming Server
QuickTime is an early media file architecture that has grown to integrate
many different types of media assets and compression formats; the QuickTime
wrapper architecture was adopted as the basis for the MPEG-4 standard. The
Streaming Server system delivers pre-compressed videos and audio, but no search
or metadata management.
Figure 11.
Pros
- Integrated deeply with Macintosh platform.
- Flexible architecture with support for large number of formats, including
mp3.
Cons
- Periodic problems that break playback on Windows platform.
- Needs edge server system for robust off-campus distribution.
- No rights management available, other than manual password "keys".
Preliminary rating
2 (lifecycle) + 2 (restrictions) + 1 (range) = 5 (total)
H. Video Furnace
Video Furnace was acquired by Dartmouth as an IP Video replacement for Cable
TV service; Dartmouth has implemented that multicast feature for campus network
users. Video Furnace also provides unicast on-demand streaming.
Figure 12.
Pros
- Locally-controlled within Dartmouth network.
- Uses session-based Java player with no caching or installed player to
improve security.
Cons
- Compensation model based on bandwidth used for Internet VoD delivery.
- On-campus only.
- Authorization system needs to be developed in-house through available
hooks.
- Does not currently support mp3.
Preliminary rating
2 (lifecycle) + 2 (restrictions) + 1 (range) = 5 (total)
I. WGBH Forum Network/Open Media Network (Kontiki)
Service that distributes videos from Boston-area non-profit partners. Now
expanding to a national scope in partnership with the Open Media Network (based
on the Kontiki Grid Platform). Evaluation of future service to be
considered.
Figure 13.
Pros
- Utilizes network of client machines; no dedicated server network
required.
- Access control, network security, desktop security, and usage control
tightly integrated.
- Supports mp3.
Cons
- Kontiki currently supports only Windows (active-X); Mac expected in next
quarter.
- Distribution only; on-the-fly transcoding not integrated.
References - WGBH Forum Network
References - Open Media Network
References - Kontiki
Preliminary rating
2 (lifecycle) + 1 (restrictions) + 3 (range) = 6 (total)
Recommendations
Given the variety of overlapping feature sets provided by each of the above
services and products, two factors need to be considered. First, what are the
prioritized use scenarios that need immediate attention, and what resource is
available? Second, which services and products that meet those needs most
effectively integrate open-standards and interoperability. With that
information, deeper evaluation of top solutions can be undertaken.
|
