At the end of 2005, Discovery Network Europe opened a new media transmission center at the company's European headquarters in Chiswick Park, West London. The broadcaster had been using Ascent Media Network Services' central London playout facility for many years, but it wanted a purpose-built transmission facility located at its new headquarters that would allow room for expansion.
The original facility was typical of turn-of-the-century playout. Interstitials and other short duration content were aired from video servers, and long-form programs played from tape using digital Betacam decks in Flexicarts. Each operator handled two channels in one room.
The move to an entirely new facility would enable changes in work practices — dubbed tapeless operation — and would accommodate emerging media formats, including HD, mobile TV and broadband delivery.
The broadcaster contracted Ascent Media Systems and Technology Services (formerly A. F. Associates) to design and build the new center, which opened in December 2005. The transmission center is operated for Discovery by Ascent Media Network Services. Ascent Media has helped Discovery Networks to circle the world with their entertainment channels by building playout facilities in Stirling (USA), Singapore and London. Ascent also operates the Singapore and London centers for Discovery.
From the new center, the broadcaster originates 48 feeds for uplink and transmission to 104 countries in Europe, Africa and the Middle East. The system has been designed so that it can easily be expanded to 60 channels.
By starting with a ground-up design, the network has been able to take advantages of new technologies that will eliminate most of the tape handling that has made broadcasting so labor-intensive. It also will make the roll-out of HD services much simpler to implement.
Designs for master control rooms generally follow two layouts. One is the single large control room “NASA-style,” and the other is separate pods handling anywhere from a single channel up 10 channels each. The separate pods are more common for stations with live programming, where operators need acoustic isolation for audio monitoring. Discovery programming is all pre-recorded, so audio quality checks can be made during ingest.
The broadcaster adopted the single control room design with a large master control area. Visitors can see this as they enter the foyer, forming a signature for the operation.
The control desks are arranged in front of a huge curved wall that monitors all the channel streams. Not all channels air for 24 hours a day, so Ascent makes a distinction between “streams” as a video and audio processing channel, whereas a “channel” is the output to distribution. Two channels (day and night) may share a stream.
The video monitor wall uses Barco DLP back-projection screens driven by Evertz MVP multi-display processors. Each stream is shown as a column, with the server outputs at the base, then the switcher output, and the off-air picture at the top. That means the operators can see at a glance where a problem lies if the off-air picture is lost.
The technical design is based on other Discovery installations around the world, with subtle changes to accommodate the different workflows of the locale. Programs are aired from video servers, using the Omneon Spectrum, with OmniBus automation controlling the playout. Each operator position has a Miranda Presmaster control panel for manual override of the ImageStore 300 switchers, which provide the channel branding and DVE processing for each stream. Videotek monitoring is used for quality control.
Programs are ingested from videotape from the broadcaster's vast tape library, but the rest of the transmission operation handles video and audio as streams and files. Ten rooms are used to ingest tapes using OmniBus software to manage the operation.
These rooms are set up for all the necessary quality control during the encoding process. One of the big advantages of file-based playout is that once a tape has been checked and encoded, that file can be aired over and over without the need for further checks; this is not the case with videotape, with the ever-present risk of dropouts. Once the operator is happy with the encoding, then he or she can use the automation system to manage the file archiving.
Programs and interstitials arrive in a finished form at the facility. Stings and bumpers can be assembled locally into packages using cuts-only editing. For this, the broadcaster uses Avid Newscutters with LANshare storage. The original program tapes are checked in and out and cycled though the ingest stations, using Xytech tape library management — an application in common use throughout Ascent Media.
The broadcaster operates in 22 languages. Original Digital Betacam tapes can carry only one or two languages. The old tape-based operation had several copies of a program tape, each with different languages, but all with the same video. Some additional language tracks are stored on DAT or DTRS tapes. Voiceovers usually arrive on MiniDisk.
The primary language is encoded with the video. The additional audio tracks are captured from other Digital Betacam tapes, but because the video has already been encoded, only the audio tracks are ingested. They are encoded as linear PCM BWAV files using Digidesign Protools. The Omneon TrackTool then allows the different language tracks to be stacked and tagged in a single QuickTime wrapper along with the main video track. At transmission, the appropriate language tracks can be selected using the tags and played out in sync with the video.
Omneon Spectrum servers are used for ingest and playout. The ingest server provides encoding and storage for 10 rooms and has a capacity of 10TB, about 45 hours per ingest room.
Mirrored playout servers provide resilience against failure. Each server has 52 playout ports and comprises two Spectrum chassis. A third group of servers is used for program quality control.
No one data rate fits all the needs of a facility, so just as the tape world uses Digital Betacam for transmission and archive and VHS for viewing copies, a file-based facility can use different data rates to best suit the application. The broadcaster uses four data rates: two for program material and two for viewing proxies.
Content is ingested and archived to LTO tape as MPEG-2, IMX, at 50Mb/s. Program files are transcoded to 20Mb/s long-GOP MPEG-2 for the playout servers. That way, there is an editable archive copy (for creating versions and promos), with a compact transmission copy to save space on the playout servers.
Any disk storage system has finite capacity. With the number of channels supported at the facility, it did not make economic sense to store the large program library on real-time disk systems that have been designed for playout. Instead, encoded files are moved to a StorageTek SL8500 data tape library. The files can be stored and recalled as perfect copies without the need for further quality checks.
In addition to the tapes and Spectrum servers, a 5TB Cisco disk store provides temporary storage for files following ingest. The server system uses Gigabit Ethernet (GbE) for file transport. The Cisco disk array and the StorageTek drives are linked in a Fibre Channel (F-C) SAN.
A Front Porch Digital DIVArchive bridges the GbE media network and the F-C SAN. This software middleware system provides all the data movement functions and additionally can transcode files between different compression formats. It acts as a crossroads between ingest, playout, storage and editing.
The software middleware system comprises 10 DIVActors, which can move data between the servers and the SAN and can also transcode (using BitScream) the 50Mb/s IMX MPEG-2 to the long-GOP 20Mb/s MPEG-2 used for playout.
All these data movements and transcoding are performed transparently to the operators. The automation system sends commands to the DIVArchive to perform processes as required.
When an ingest operator is happy with an encode, the automation system instructs the DIVArchive to copy the file to the StorageTek and to create the long GOP copy, also archived. Ingested programs are stored on the disk array for 48 hours, so they can be accessed immediately without the need to load a tape and read back to disk.
Recall of program files from tape is driven by the playout schedules. The automation system requests any content missing from the playout servers from the software middleware system, which then restores the file from tape to disk.
With 8500 slots, the StorageTek library can hold about 85,000 hours of video files on LTO format tapes. Each of the 12 drives can read at 34MB/s, which is about five times real-time for a 50Mb/s file. The DIVArchive uses StorageTek's ACSLS Manager (Automated Cartridge System Library Software) to control the robot.
Omneon uses the QuickTime format to wrap the media files on the servers. To interchange content with the NewsCutters, a DIVActor converts these files to Avid OMFI format. The finished packages in OMFI format are converted back to QuickTime with Marquis Margate before return to the storage system. It is possible to make a partial restore of a file from the SAN, if a short segment is all that is required from a long program.
The old tape-based operation used VHS tapes for viewing. The new facility has moved to file-based browse. Two systems are used: one for program and interstitials, and the other for transmitted material.
During the ingest operation, 700kb/s Windows Media 9 files are encoded in parallel to the MPEG-2 file. IPV encoders are used for the ingest. These files are stored on a 9TB IPV browse server with a capacity of 35,000 hours of video.
For regulatory compliance, each outgoing channel is encoded in 430kb/s Window Media 9 format. These are stored for 90 days on a Masstech disk-based MassLogger. The files are exposed to users for general viewing purposes from a Web server.
Video and audio system
Two NVISION 8256 routers combined to give a 512 × 512 matrix provide the main signal switching for the facility. All video cabling and infrastructure can support HD so that Discovery can upgrade channels as required. All the cabling and infrastructure is all SDI, with audio embedded in the video, supporting up to eight AES pairs.
Files are moved over a Gigabit Ethernet network. A group of Cisco Catalyst routers and switches form a 1024-port network for media. (Office traffic is handled by a separate network.) Unlike most IT installs, Ascent has used video-style patch panels for Ethernet, rather than patching on the back of the network switches.
When the systems integrator was purchasing for the project, it found that each software vendor specified and qualified a different PC platform. This was not viewed as ideal for maintenance. Instead, it insisted that everything was tested and run on a common platform, the HP DL3800. A total of 140 HP servers are used to run the control software for the transmission system.
Back office and asset management
In a drive to improve efficiency, Discovery International businesses have centralized their systems within their worldwide offices in a project called Discovery One. This enables corporate reporting across each region, as well as the ability to purchase programs and have this information available to program schedulers worldwide.
The management system runs on IBMS from Pilat Media, with a regional hub for each continent (Europe, Asia and Latin America). It covers more than 150 countries/sales offices, with more than 400 users. The finished transmission schedules are exported from IBMS to the automation system.
Staff has comprehensive viewing facilities of programs or transmitted materials. An Artesia digital asset management system is used to store general metadata about programs. The Artesia user interface embeds an IPV client so that the users can view the video proxies with full VCR-like controls.
Staff can also search and view transmitted material using the Web server attached to the MassLogger. The OmniBus as-run logs are processed by the logger to form the index for searching. That means staff can rapidly locate commercials by time, name and channel, or check a transmitted program.
The bottom line
With the advantage of a new building, Ascent has achieved a clean look in this transmission center. The old central London center was full of tapes. There was a large tape library; plus, every transmission suite had stacks of tapes. Staff pushed carts loaded with tapes up and down the corridors.
The first thing you notice at the new facility is the lack of tapes. A small dispatch area is used to check-in tapes for ingest and then to return them to archive storage.
Besides the lack of tapes, with all the attendant physical handling, Discovery is beginning to see advantages from file-based transmission. The browse system provides better visibility of content to those in program planning. Back-office staff can check content without the need to order a VHS dub and then wait while it is copied and delivered. Instead, users can view it instantly from their desktops. The intention is to extend the use of browse for other applications.
The broadcaster has now embarked on the huge operation of ingesting the program tape library. Because the new transmission center needs less staff to run a given number of channels, staff have been redeployed to the ingest rooms. One of the bonuses of the ingest operation has been the chance to audit the library. Users can confirm for each program the languages of the audio tracks, closed captions and subtitles.
The move to file-based playout will transform the workflows for Discovery, giving it a new flexibility to add channels or migrate to high definition, without the upheavals required with tape-based systems.
Technology at work
Avid Newscutter NLE
Barco cDR+67-DL display wall system
Cisco Catalyst 6500 cores, 3750 edges network routing and switching
Evertz MVP multi-display processor
FrontPorch Digital DIVArchive archive management and transcoding
IPV SpectraView WM9 encoding
Presmaster control panel
Imagestore 300 switchers
NVISION NV8256 digital video router
Masstech MassLogger compliance recording
Omneon Spectrum video servers
OmniBus Colossus transmission suite and broadcast control suite
Pilat Media IBMS program scheduling
StorageTek SL8500 tape library
Videotek VTM monitoring
Xytech tape library management
Discovery Network Europe
Sam Cabraal, sr vp technology and business services
Paul Newman, vp network operations
Ascent Media Network Services
Catherine Bell, vp operations
Diana Baur, head of operations, Chiswick Park
Ascent Media Systems & Technology Services
Joe Berini, sr project manager
Stuart Parkinson, project engineer
Steve Samwell, project engineer