Section Four: Digital Video Client/Servers
Open Systems Design

Open systems design is a catch-all concept encompassing a variety of standards and processes. Open systems design, based on adherence to standards in networking topologies, file formats supported, file storage and management, data transmission and client reception, is a critical criterion for selecting a system that fits seamlessly with your legacy infrastructure to merge digital video with current services. Open systems support also provides your best guarantee that the VOD system selected will grow with your infrastructure and support future needs.

Another issue to consider when looking for an open standards-based system is the increased amount of collaboration — in the sharing of video assets to create large "virtual" collections; in the sharing of multicast programs, and, over time, the merging of videoconferencing with video on demand as the H.323 videoconferencing over IP standard matures. Increasing demands will be made on digital video systems for distance learning, resource sharing and collaboration across institutions. An open design may not be a critical issue at time of installation but will grow rapidly in importance. You do not want to commit to a proprietary solution, and encode numerous assets, only to find the system will not scale beyond your department or institution.

A completely open system will transparently support digital video files in any format, a wide range of encoding and decoding hardware and software, to a range of clients, including Windows, Mac and UNIX. Service will be provided by Windows and UNIX servers, utilizing a variety of TCP/IP and UDP/IP transport protocols, including RTP, RTCP, RTSP and IGMP. An open system will have complete web capability, including web plug-in and helper-app client software, remote server and file management via the web, web-based search engine support, and as well as http file access and security.

A truly open system should interface transparently with the systems of other vendors so that two or more institutions could collaborate to create "virtual" collections and services to support user needs. Imagine, for example, users at two institutions, with different digital video client/server systems, transparently sharing a video newsreel collection on life in the U.S. during World War II at one institution and documentary war footage at the other institution. In addition, history lectures from both institutions are transparently viewed via IP multicast by users at either institution.

Full interoperability between disparate systems is a future enhancement that ViDe hopes to explore in the near future with selected vendor partners. Currently, this interoperability is not available, or at least not actively developed and tested, by digital video vendors.

Components of open systems design are discussed below:

Open Networking
Simultaneous unicast streams require a large amount of bandwidth. As your needs grow, it is important to be able to migrate your services to a higher-bandwidth network. Also, future applications involving full MPEG-4 functionality — accompanying text, 3-Dimensional images, object indexing and manipulation, etc. will require more bandwidth, even if the stream number stays the same. An open system will support every flavor of Ethernet, including switched-10, 100BaseT ("Fast Ethernet"), Gigabit Ethernet, as well as ATM (ATM with classical IP (CLIP), ATM with LAN emulation (LANE), and native ATM with Quality of Service (QoS). Depending on your existing topology, or the need to collaborate with another institution or department with a different topology, Token Ring support may also be important to you. Transport protocol support, including TCP/IP, UDP and RTP/RTCP is also a critical requirement for managing network traffic and stream quality. For dial up access, cable and ADSL support can be important considerations.

The ten vendors participating in the RFI are fairly strong in open networking support. Most responded that they support Ethernet and any TCP/IP based network topology. IBM, InfoValue, SGI and Starlight explicitly support FDDI. IBM and InfoValue explicitly support Token Ring. CISCO, Concurrent Computer Corporation, IBM, InfoValue, SGI and 3CX support ATM, with InfoValue, SGI and CISCO explicitly supporting LANE, CLIP, and native ATM over QoS. Panasonic states support for "segmented Ethernet 10BaseT protocol. Co-exists with other popular networks." CyberStorage states support for "All major LAN & WAN interfaces." Advanced Modular Solutions & Digital Bitcasting Corporation support Ethernet and IP-based network topologies.

When selecting a system, verify with the vendor which delivery protocols are supported. Protocol support should include both TCP/IP and UDP/IP protocols, including RTP, RTCP and RTSP. RSVP, for resource reservation, is a good protocol to support, for long-term scalability. CISCO and IBM explicitly support RTP, RTCP, RTSP, and RSVP. No information is currently available for Concurrent Computer Corporation, CyberStorage, InfoValue, Panasonic, SGI or Starlight. Advanced Modular Solutions/Digital Bitcasting supports TCP, UDP, RTSP and PNA protocols. 3CX notes support, more generically, for TCP/IP and UDP/IP protocols. IGMP (IP Multicasting) should be supported for multicasting. Advanced Modular Solutions/Digital Bitcasting, CISCO, IBM, InfoValue, SGI, Starlight, and 3CX explicitly note support for IGMP. Concurrent Computer Corporation and Panasonic do not currently offer IP multicasting service.

Server Platform
Support for off-the-shelf third-party servers, rather than vendor-proprietary, and for NT and UNIX operating systems offer the most purchase and deployment flexibility. However, open networking support (discussed above) and scalable server configurations (discussed later) are more critical issues, unless you have a need for a specific server operating system or if low cost is a driving factor. Windows NT servers do not scale as well as UNIX servers, but they will be less expensive than UNIX and can be supplied off-the-shelf by a third-party server vendor, giving you more options for comparison shopping.

CISCO, CyberStorage, InfoValue, and 3CX require NT servers. Starlight supports both Windows NT and Solaris for its StarWorks VOD server but requires Windows NT for its StarCenter management server, StarCast multicast server, and StarLive distance learning/streaming media application server. SGI requires its proprietary UNIX (IRIX) server platform — the Origin series. For very small (1-20 stream) installations, the IRIX O2 workstation is an alternative. Panasonic requires a Sun Solaris server. Concurrent requires a server with its PowerMAX OS proprietary UNIX operating system. Advanced Modular Solutions/Digital Bitcasting offers NT and LINUX-based stream servers. IBM offers both it's proprietary UNIX (AIX) and Windows NT server solutions.

File Format Support
One of the most important considerations is file format support. All ten vendors support the MPEG standard, but implementations of these standards vary widely. Question the vendor closely about MPEG implementations, particularly in the following areas:

MPEG1 and MPEG2 Unicast. Nine vendors responding to the RFI offer MPEG1 and MPEG2 support, but not necessarily for all encoding and decoding systems. CISCO offers MPEG1 Unicast, with MPEG2 Unicast available with version 3. InfoValue states that it supports all available off-the-shelf hardware encoders and decoders. CyberStorage states that it supports any type of digital content and offers automatic support for any hardware decoder.

MPEG2 encoding and decoding support is particularly critical. Vendors may require hardware decoders and may only work with specific models. Some vendors only support MPEG2 streaming at the lower bandwidth spectrum, which is an important consideration for encoding. Bandwidth range — a critical issue! — is discussed in a later section.

It is critical to verify support for the encoding system already in use to create video files and for legacy hardware and software based decoders on client workstations. I cannot over-stress the importance of this issue! If you have not purchased an encoding system, the author recommends selecting the client/server system first, or selecting the two in tandem. All vendors should test encoding systems and decoder cards for compatibility with their client/server streaming software.

Of course, you will want to verify support for your encoding and decoding systems of choice, for any vendor. The author would recommend putting full support for your selected encoding system(s) and hardware or software decoding system(s), including the required bandwidth range and/or encoding level, in the purchase order and/or purchase contract as a condition of sale, so that you are assured of complete compatibility between the files you create, the system storing and serving those files, and the client desktops receiving and playing back the files. Vendors support the constrained bit stream 1.5 Mbps for MPEG1, but a wide range of bit rates for MPEG2. Bitrates (single stream and aggregate) are discussed in the Scalability section.

MPEG1 and MPEG2 Multicast. Concurrent Computer Corporation and Panasonic do not currently support IP multicasting. Panasonic will offer IP multicasting in VNS release 3.1, due in early 1999. CISCO, Starlight, and 3CX currently offer MPEG1 multicasting but will support MPEG2 multicasting in the next release. All other vendors responding support multicasting, specifically IGMP (Internet Group Management Protocol) for IP multicasting. Those vendors did not specify MPEG2 multicasting.

Multicast streams may be handled differently from unicast streams. Verify whether MPEG1 and MPEG2 streams are both supported, as well as the bitrate range supported for multicast. Verify with each vendor particularly whether MPEG2 multicasting is supported, as well as the transmission bitrate. It is not uncommon for a lower MPEG2 bitrate to be supported for multicasting than for unicast. If high-bandwidth multicasting, in applications such as digital medicine or modeling, is critical to you, be sure that the vendor can support MPEG2 multicasting now, or that this service is in development for a contractual commitment. Also ask whether video and audio are transported as separate streams and, if yes, how synchronization of the streams is assured.

Vendors generally support both live and stored multicast broadcasts. Some vendors bundle encoders and recording software so that a live analog feed can be encoded on the fly. An important question to ask is whether a specific encoder/recorder is required for live broadcasting. If so, you will want to insure that files are produced in a standard (MPEG1, MPEG2) medium to high-bandwidth format to create and store assets of a consistent quality with those you already own.

Low-Bandwidth File Format Support
Systems that offer completely open file streaming support will be indifferent to encoding format for storage, basic asset management and streaming. Starlight, Panasonic, InfoValue and CyberStorage all state transparent unicast streaming support for any file format. Advanced Modular Solutions/Digital Bitcasting state that they offer "open file streaming support" with the G2 RealServer. Open file streaming support can be easily verified during a vendor demo by providing files in a range of low-bandwidth formats, since encoders are either free or very inexpensive for most low-bandwidth formats.

Low-bandwidth videos in different formats and bandwidths can also be borrowed extensively from the web, with permission of the page owners, for demonstration purposes. It is always a good idea to test streaming and client functionality with your own files, as well as the canned files provided by the vendor. Before beginning the demo phase of your evaluation process, gather a number of video files (high-action, high-color, talking head) and audio files (range of speaker voices — high pitched, low-pitched, etc., range of music types, including singing and instrumental only) for testing across vendor platforms.

While MPEG-4 has been adopted as a standard, it is not yet available except in alpha and beta test, for encoding, storage, streaming and playback. Proprietary low-bandwidth formats must be supported for Internet streaming outside the building or institution LAN. All vendors responding support one or more low-bandwidth formats, in addition to MPEG1 and MPEG2.

CISCO states that IP/TV supports a variety of codecs, including H.261, Indeo, Cinepak, Vxtreme and M-JPEG but notes "in some cases, specific hardware encoder or decoder cards may be required." IBM 's VideoCharger supports MPEG1, MPEG2, QuickTime (through its ActiveMovie implementation), AVI and Bamba (IBM proprietary format). 3CX supports QuickTime. SGI supports RealVideo, RealAudio and H.263. Advanced Modular Solutions/Digital Bitcasting provides the Progressive Networks' RealSystem G2 for video and audio with MPEG1 and MPEG2 as a plug-in application to the G2.

Which proprietary low-bandwidth formats are best? This is mostly an application-specific decision. In the author's opinion, RealVideo and Audio are widely available, generously supported with very good free clients, free encoders, free plug-in applications, free server software (20 streams at date of writing), etc. File quality and streaming are excellent, as is support for the SMIL (synchronized multimedia integration language) standard for incorporating digitized text for audio file transcripts and distance learning. Other new features include RealFlash, RealMedia's integration of Macromedia Flash into its authoring product. The RealSystem seems determined to maintain its enormous presence on the web. If plug-in integration for streaming MPEG-4 is offered, and the current bandwidth streaming limitation of 900KB overcome, RealMedia will remain an excellent low-bandwidth solution.

QuickTime's file format provides the wrapper for MPEG-4. The file format is excellent for download and play, but until recently, streaming capability was lacking. QuickTime 4.0, which was released in April 1999, incorporates streaming functionality and protocol support. In addition, QuickTime 4.0 provides built-in support for digital video, including MiniDV, DVCPro, and DVCam camcorder. QuickTime 4.0 will include source code, allowing great flexibility for custom APIs. The compatibility with MPEG4, while not at the object recognition and manipulation level, is a real plus.

At the present time, the author would look for both RealMedia G2 and QuickTime 4.0 file formats to be supported. At a minimum, insure that at least one of the two — whichever interests you the most for your applications — is supported. Mature MPEG-4 solutions are probably a year away, and a year is a long time in the fast-paced world of the Web. RealMedia G2 and QuickTime 4.0 offer significant enhancements over previous software versions. Be sure that the video client/server system supports the latest release for your proprietary low-bandwidth format, or has firm plans to do so.

Client Support
Your client base is the end user desktops that will play your streaming video files or multicast transmissions. The client base can rarely be completely identified in advance and is therefore a critical concern for most installations. Your client base includes workstations you directly support, in the building where the server resides, customers accessing videos remotely from home or office, as well as any authorized visitor to your web site. Be careful about the assumptions you make concerning your client base. The best way to discover just how many MacOS clients you support is to offer a service with a Windows-only client!

All responding vendors provide Windows players. Support for MacOS and UNIX is another story. Advanced Modular Solutions/Digital Bitcasting uses the RealMedia G2 client software, supporting UNIX, Windows 95/98/NT and, in spring 1999, MacOS. CISCO's IP/TV supports Windows 95/98/NT and can interoperate with the MBONE VIC/VAT client on UNIX platforms as well as the QuickTime streaming extension on the Mac. Concurrent's MediaHawk Player runs under Windows 95/98/NT, and under any application that uses Microsoft DirectShow 5.0, including ActiveMovie.

CyberStorage supports Windows 95/98/NT with MacOS in development. The CyberStorage response notes that UNIX and MacOS can use NFS protocol to access the server and use native media players rather than the CyberStorage client. IBM supports Windows 95/98/NT and has a MacOS client under development.

InfoValue's QuickVideo on Demand player runs on Windows 95/98/NT clients. Panasonic offers both a Solstice NFS client and a Java media player, utilizing the browser-embedded ActiveMovie player. Client playback operates on UNIX, Windows 95/98/NT and MacOS. SGI supports Windows95/98/NT, MacOS, and IRIX.

SGI also provides client support for Solaris and AIX, which must be licensed from a third-party developer, RABA. The ixJet Streaming and Live clients from 3CX runs on Windows 95/98/NT, MacOS, and UNIX. An SDK for the Streaming and the Live Clients provides Java-based API development including a Java applet for a cross-platform client plug-in.

Verify client performance on your existing UNIX and MacOS client desktops. It is critical to insure that the vendor's players work with the versions and flavors of OS software that you support. UNIX clients may not run on Linux, a very popular UNIX desktop OS, for example. Compare the Windows clients with MacOS and UNIX clients for functionality. Are all features, such as fast forward, rewind, freeze frame, bookmark, resize, etc. supported? If not, are there plans to add missing features? If you must use a native or third-party client rather than the vendor's client, look for tradeoffs in appearance, functionality and streaming performance. Vendor players will include proprietary communication with the server for managing the stream, which could noticeably affect performance.

Web Support
The Web has become a kind of meta-operating system, providing connectivity, database and document management and support, as well as a common interface for computer-based communications of all kinds. Web integration and support is a very important component of any digital video client/server system. Client/server systems use the Web and its supporting protocols for access to digital video files, but also for asset management, indexing, security and remote server administration. At a minimum, a VOD client/server system should support http access-both for asset streaming and remote management for asset loading, backup and file transfer among servers. In addition, Web-based security and client playback through a Web page should be supported.

3CX's ixJet Streaming Server and Client and ixJet Live Server and Client include an SDK with ActiveX control APIs for Windows applications and a Java package for cross-platform applications. The SDK includes HTML embedding for Web pages and for creating a client plug-in using either ActiveX control or Java applet. IxJet Network Video Presenter, the Web-based authoring and presentation tool, supports the Secure Socket Layer for controlling access to distance learning applications through user authentication and data encryption. InfoValue provides an API that can be used for Web-based applications and is compatible with a wide range of development tools, including Visual Basic, Visual C++, Macromedia Director, among others, including database tools. InfoValue's API is designed to be open and transparent to the application development tool, with the stated goal that "the best API is no API."

Advanced Modular Solutions/Digital Bitcasting provides the Web capabilities of the RealMedia G2 client/server software, including SMIL and Flash authoring and playback capabilities in a Web environment. In addition, authentication is based on the HTTP standard, RFC 2069. CISCO's IP/TV includes a Web plug-in for launching and configuring on a Web site as well as a web button on the viewer to launch a predefined Web page. SGI's WebFORCE MediaBase also uses a browser plug-in that can be embedded in Netscape Navigator or Internet Explorer browsers.

Panasonic provides a Java viewer for Web-based access, as well as remote administration of the server via the Web. IBM's DB2 Digital Library VideoCharger Player provides an external helper view application as well as a browser plug-in viewer for embedding the viewer in a browser window with a subset of the standalone viewer controls. IBM also provides a video-on-demand Web page for searching and selecting videos for playback.

Other Open System Components
In addition to the open system components listed above, it is important to look at several other network components when evaluating vendors:

Security. Does the vendor support http security features? Will the system support kerberos? Will the vendor's own security system interoperate with the institution's security system? Security features to investigate include authentication (access to service), authorization (access to specific files within the service) and encryption (security at the file level). The levels of security to be supported depend on your needs. You may want encryption for multicast distance learning applications where a fee for "attendance" is required, for example.

Database. What database is used to provide file management and administration? Is the database ODBC-compliant? -- CORBA compliant? Many vendors provide a database management system such as Access, Informix, etc. but also provide an API for Oracle.

Storage. A digital video client/server system should support a wide range of storage and HSM (hierarchical storage management) options, including JBOD ("just a bunch of disks") arrays, RAID, optical storage (CD-ROM and DVD), FC-AL (Fiber-Channel Arbitration Loop) as well as storage methods such as robotic manipulation and jukeboxes.

Application Standards Support. Most applications are governed by a suite of standards specific to the application, such as SMIL (synchronized multimedia integration language) for multimedia presentations. The Real G2 client supports the SMIL standard. Asset cataloging and indexing includes numerous standards for creating catalog, or metadata, records, for searching metadata records and retrieving related assets. IBM supports the Dublin Core metadata standard, a robust, general purpose metadata standard for cataloging Web information, and also the Information Retrieval (Z39.50): Application Service and Protocol Specification, a client/server network protocol that enables a client to access any Z39.50 enabled server (one or many) to search databases, retrieve records and organize and display the retrieved records. Z39.50 is not yet a mature standard but has the capability to greatly expand access to information at the database record level. 3CX offers metadata support compatible with the IMS (instructional management systems) Meta-Data standard in its ixJet Network Video Explorer component. IMS Meta-Data is a cataloging standard proposed and supported jointly by Educom and the National Learning Infrastructure Initiative (NLII) and is intended to standardize access to courseware and distance learning tools.