The June 15 meeting of the Washington DC section featured a presentation by Quantel's Chief Technical Officer, Jon Pannaman. 16 members and guests attended the event, which was held at the Hilton Hotel in Mclean, Virginia. The purpose of the meeting was to present the philosophy, rationale, and technology behind the Quantel LAN/WAN production/post-production workflow system based on 'Zone Magic' technology, and to demonstrate its operational capabilities. The remainder of this report is a summary of Jon Pannaman's presentation. The Zone Magic system runs on high-powered Windows2000/XP-based workstations and VxWorks data servers. The system is scalable and expandable without rebooting ó it automatically tracks and adapts to changes in near real time. It supports mixed-format and mixed-resolution local and remote program sharing and production that can span a room, a city, and the entire world.
Wherever possible, Quantel selected open architecture software and standard platforms as a foundation. When system conception and development began around 1996, the state of processor technology led Quantel to prefer the Intel chips to the Motorola series. Also, options such as Linux and MacOS weren't ready for this arena, where extremely high reliability and fault tolerance, plus the ability to run many widely used third-party applications were, and are, critical requirements. If the system were being developed today other choices might be made, but Quantel's and their users' experiences with this system have revealed no substantive problems from use of the Windows operating system. Consideration of alternatives depends on customer demands. The system runs on a 1Gbps Ethernet, with faster networking under development for use where needed.
Even in the 1990s VxWorks was a respected real-time multi-tasking industrial Unix-like operating system used in many government and military applications. It has since been used in the Mars Exploration rovers Spirit and Opportunity, a Linksys wireless router, and in a ReplayTV DVR; Boeing plans to use it in their new 787 airliner. VxWorks also has an excellent history of immunization from viruses and other malware. MySQL is the open-source database used for storage and management of all program data.
The underlying storage concept is to have program data (video, from standard definition (SD) up through 4k digital cinema, plus associated multiple channels of audio) stored directly via SDI I/O (not over the Ethernet) to a RAID-5 server, with each video frame stored separately, along with its metadata, which includes identification of the video acquisition format. SD video is stored as IMX I-frames. HD video is stored as DV100 I-frames. Metadata is stored in AAF format, and can easily accommodate new SMPTE or other metadata definitions, requiring only a simple software modification. During acquisition, the program video is stored two ways ó in full resolution, and in a low-resolution browse format. There are options to allow the data to be stored in multiple locations, though the operation of the system and its reliability generally donít warrant the extra expense.
The editor is isolated from direct computer operations ó he uses pull-down menus that automatically update when programs are added or deleted, or when additional servers are brought online. The user need never be concerned about where the data is stored; the system handles that behind the scenes. While many customers allow access to all program data from all workstations, areas and zones can be set up to provide limits.
When the editor selects a clip for use, the browse clip is downloaded to the editorís workstation via UDP (instead of TCP) over IP. The Quantel workstation software stack performs all error correction. While the workstation does run the Windows OS, only layer 1 (physical), layer 2 (data link), and some of layer 3 (network) of the OSI seven-layer structure are used when performing Quantel's functions. Quantel's workstation software bypasses the rest of Windows (they could not sectionalize the MacOS in the same way), using their own drivers and hardware resources, optimizing performance for editing functions while minimizing Windows' idiosyncrasies. Having Windows on the workstation supports the use of many third-party software packages that the user prefers for production and post-production functions. The structure of their workstation package enables users to buy only the software and specialized hardware to use on their own workstations, and simplifies Quantel's ability to migrate the package to other hardware and operating systems, if sufficient demand arises.
The editor can perform any desired production/post-production operations on the clip, just as on any editing workstation (the latest release includes speed adjustment with coincidental audio pitch adjustment). The difference is in what happens to the data. Any operations that don't require a change to one or more video frames creates an edit command list ó it doesn't alter the source data. On the workstation, the editor sees the effect implemented in the browse copy locally stored. If changes to one or more frames are performed (such as fades or color correction), copies of only those affected original-quality frames are immediately and invisibly downloaded to the workstation, where the changes are made to those copied frames. When all editing is completed, and the editor has (properly) named his edited program, the edit command list and the modified frames are automatically stored on the server.
When a scheduler identifies a program and location for broadcast (publishing), the system immediately moves a copy of the original frames and modified frames, in accordance with the edit command list, to the broadcast location cache storage. At all times, the original data is available to others who might want to copy or edit it for a different purpose. Common Object Request Broker Architecture (CORBA) provides asset management control to prevent deletion of original data that is in use by others, in a manner similar to some better CAD systems. CORBA enables heterogeneous applications in various languages on various platforms to interoperate.
Critical to obtaining the proper system configuration, and to its successful use, is the customer doing their homework - thoroughly describing how the system will be used, source and broadcast formats, network data and video bandwidth requirements, access control needs, expansion plans, and program file naming standards. It is also necessary for the customer to have the equivalent of a database manager to determine when clips can be deleted from the master storage, and to determine when the system will need more storage. The concepts behind Quantel's system have been carefully crafted toward freeing the users from being computer experts, enabling them to concentrate on their function, not the equipment.
Thanks are due to Quantel for hosting the meeting and for the excellent refreshments. Thanks also to Quantel regional sales manager Rob Foreman, who coordinated the arrangements, and to the Quantel support team for their help with the demonstration.
-David J. Weinberg, Section Manager
John Pannaman, Quantel, speaker at the Washington DC June meeting