Capitol Broadcasting Company, Inc., (CBC) is a diversified communications company that owns WRAL in Raleigh, NC. WRAL is the only station with all its photographers shooting all HD in the field with 29 DVCPRO HD cameras, representing the only all-digital, all-HD news workflow in the country. In this, and other innovations, the technology at WRAL and CBC often has been so far ahead of the pack that employees helped write instruction manuals the companies had to create to accommodate their latest innovations.
A file-based workflow is essential to manage the high-volume requirements of WRAL.com, which is the most visited local TV website in the country. Since WRAL.com launched in January 1996, it has grown to more than 30 million page views per month by more than 1.2 million unique users. WRAL.com streams more than 500,000 on-demand video clips and serves thousands of live streams of its newscasts each month.
With the recent addition of the BitCentral Précis HD newsroom production system, WRAL is the first station to adopt a full HD file-based workflow. At WRAL, and throughout CBC, the quality of the consumer’s experience is paramount.
OLD TAPE WORKFLOW
The tape workflow at WRAL has been unique to the industry since they launched their completely digital, full-HD workflow in 2001. For ENG, WRAL utilizes 29 sets of Panasonic DVCPRO HD cameras and associated field gear.
In order to preserve the all-digital, all-HD workflow, ENG crews are required, in most cases, to physically bring content recorded onto DVCPRO HD tapes into the station because the microwave systems on their trucks are still analog. At present, when video needs to be sent in via microwave, it is downconverted and remains in widescreen standard definition for that broadcast. Subsequent broadcasts will utilize the HD tapes after they arrive at the station.
Once at the station, the HD tapes are edited on dual Panasonic DVCPRO HD 150 decks. The edited stories are played to air on tape and the archives are also tape-based.
FILE-BASED WORKFLOW
The first phase of the transition to a file-based workflow is within the station. The tape-based DVCPRO HD cameras will continue to provide service to the WRAL news team, and will remain incorporated into the new workflow until file-based HD cameras capable of recording 1080i and suitable data rates become available.
During phase one, WRAL designed and implemented two separate dedicated LANs for the movement of HD video throughout the plant. One LAN is dedicated to marketing and promotions video editing, and the other is dedicated to the new newsroom production system, Précis-HD.
For the Précis newsroom production system LAN, a gigabit Ethernet-based network has been run with standard CAT6 cabling. The Précis workflow is constrained to its own LAN at WRAL because of the mission critical nature of news and the desire to minimize the effect of the transfer of HD video files across legacy networks. All equipment related to Précis will be totally isolated from the Internet.
In addition to the networking requirements, WRAL had a number of system requirements for the conversion to a file-based workflow:
- System must maintain full 1080i resolution without artifacts.
- System must maintain an open architecture that allows easy repurposing of content.
- System must provide full integration with 24-hour cable news channel.
- System must provide newsroom software integration module that utilizes a single point of interaction for producers, writers and directors.
- System must provide online archives capable of saving all WRAL news footage, which can be retrieved at a moment’s notice for utilization by the news staff.
- All media must be located on common storage so it is available to all users on the network at all times, from raw video to archive.
- Editing save times must be no longer than 1.5 times realtime with full resolution 1080i.
- Edit stations must be format agnostic and accommodate HD and SD resolutions of MPEG-2, MPEG-4, Windows Media 9, FCP and AVI all on the same timeline without rendering.
- System must have ability to ingest simultaneously from 4 DVCPRO HD decks at 100 Mbps to common storage.
- System must have ability for up to eight edit stations to operate without slowing down at peak times with all content accessed from common storage.
WRAL’s Panasonic HD 150 decks are connected to the Précis HD edit station via an HD-SDI interface and RS-422 machine control. The ingest stream is generated as the edit station captures content from tape using the Canopus HD AVI Codec with the DVCPRO HD resolution of 1280 x 1080/60i at 100 Mbps. Users control the ingest from within the editing interface via RS-422, and if desired, mark in and out points for a batch capture from tape.
The requirement to support four simultaneous ingest streams to common storage from the HD decks was one of the most important considerations. These four DVCPRO HD 150 decks ingesting simultaneously at 100 Mbps are well within the capacity of the Gigabit Ethernet connection and the RAID array on the Précis editing server that was installed specifically for high-bandwidth HD editing. The software on the editing server sequentially writes each stream to the RAID array and eliminates contention of resources between users who are editing and those who are ingesting.
When editors are finished with an edit session and want to save their story, they click the save button on the editing interface and a screen is displayed listing the active shows. The editor selects the show they are working on and all the stories within that show are displayed. They click on the desired story and the edited video is automatically associated with that story and ready to go to air. The edit is conformed at this time and the story is ready to go to air in about 1.5 times realtime.
After a thorough evaluation and benchmarking, WRAL and BitCentral chose to outfit the newsroom edit suites with server-class workstations powered by the new AMD Dual-Core Opteron 280 Processor, Canopus Edius Pro-Broadcast, Canopus HD I/O boards and additional software from Canopus called “SpeedEncoder.” SpeedEncoder fully utilizes the processing power available on a dual-core, dual processor system. During testing, BitCentral benchmarked a 40-second editing project populated with various HD AVI and SD MPEG clips, transitions, video filters and other effects. Using SpeedEncoder, the project took approximately 63 seconds to save to an HD 37.5 Mbps MPEG-2 file on the NAS. The format WRAL chose for saved video is 1080/60i Long GOP MPEG-2 at a data rate of 37.5 Mbps. The resolution was kept at the camera original 1280 x 1080/60i.
Once an editor deposits the finished MPEG-2 video by saving it to the story, Précis automatically creates proxy videos and JPEG images for the browser interface and transfers the media to the redundant pair of Précis HD play-to-air servers for playout. Stories can be automatically archived in long-term storage, or sent to the archive manually by the producer flagging the stories to be archived in ENPS.
The online archive system can utilize any local or network-attached storage. The initial archive is 3.5 TB located on the content server. Additional archive capacity is located on three SCSI-attached 4 TB SATA arrays. The content server and the 4 TB SATA arrays are 2RU and each use 12 400 GB hard drives in a RAID 5 configuration. Additional storage can be added at any time to Précis by entering the network address or drive letter into the administration interface.
WRAL estimates that news operations will contribute approximately 764 hours of news to their online archive per year. Based on the chosen format of MPEG-2 1080i at 37.5 Mbps, BitCentral specified 13.5 TB of annual storage requirements across the content server and additional 4 TB SATA arrays.
MPEG-2 at 37.5 Mbps was selected to provide WRAL with appropriate image quality and long-term storage feasibility. In addition, online archiving provides the newsroom with easier and quicker access to the stored video. Keeping the archived material within the system also eliminates the need for any additional labor or facilities.
WRAL’s feasibility study compared the costs of keeping the broadcast video on hard drives as specified by BitCentral using a robotic tape library. Employing all hard drives for storage, backed up with a small robotic library using LTO-3 Data Tape broke even at 35 TB with a larger robotic data tape based system with SGL video library management software. The SGL software automatically matches the broadcast video to the proxy and metadata. Based on rapidly declining hard drive storage costs, WRAL chose the system specified by BitCentral because the ROI for the larger system would have been nearly four years.
WRAL previously installed a dark fiber link between the station and transmitter site, so the backup LTO-3 system will be located there. This off-site backup system will consist of a redundant BitCentral content server providing disk backup capability, which is attached via SCSI ultra 320 to an Overland Neo robotic tape library with approximately 12 TB of internal capacity. Backups will be performed using Veritas Backup Exec from the in-station archives to the disk-based content server located at the transmitter site. The software will then back up from the content server to the colocated tape library. Backups will be done in 4 TB volumes in order to ensure practical full backup times.
NETWORKING REQUIREMENTS
The Précis LAN at WRAL contains the eight Précis HD edit stations, content servers, edit servers, and redundant play-to-air servers. The Gigabit Ethernet switch is a 24-port Dell 5324, which was chosen because it supports Jumbo Frame and Link Aggregation. With link aggregation the throughput between the switch and edit server can go as high as 1.8 Gbps.
This is faster than the edit server can read or write data to its RAID 10 SATA array. All the equipment on the Précis LAN is on its own router and has a fixed IP address. For security purposes they are tied to each other by IP address. Even though the edit stations do not have access to ENPS, they can view the rundowns and scripts from the Précis browser-based interface or in a user interface module developed by BitCentral that plugs into the editing software.
WRAL does not plan to move any video file traffic through the router/firewall. Based upon this layout, WRAL has concluded that a nonproprietary gigabit network can support 8-10 edit stations editing full resolution 100 Mbps HD off common storage.
FORMAT CONSIDERATIONS
There is always a tradeoff between file size and quality. The objective at WRAL was to maintain excellent quality at the lowest possible file size. Since most of the components of the Précis system are nonproprietary, the video formats are mostly at the discretion of the user. There are two places in the workflow where WRAL could choose formats. The first is the acquisition format on the raw video side and the second is the playout format.
All raw video is managed on a specialized editing server designed to handle multiple simultaneous edit sessions.
Currently WRAL is capturing from tape with edit stations directly over a Gigabit Ethernet network to the edit server. The capture data rate is 100 Mbps using a DVCPRO 100 based codec. This acquisition format was chosen because it allows fast scrubbing and it was the lowest data rate codec native to Edius Professional. The Panasonic cameras capture at a resolution of 1280 x 1080/60i and the capture format needs to be compatible with this resolution, or moray patterns (noticeable as rainbow patterns on bright edges of the video) will develop in the video.
Out of all commonly used formats—MPEG-2 Long GOP, MPEG-2 I-Frame only and DVCPRO HD at 100 Mbps—WRAL engineers determined that MPEG-2 Long GOP offered the best picture quality at the lowest bit rate. I-frame-only formats produce excellent images, however, they are not as efficient as a long GOP format and are wasteful of bandwidth and storage. MPEG-2 at 37.5 Mbps with a 15 frame GOP structure was chosen as the highest quality and most efficient format. The next consideration was the data rate and format within Long GOP MPEG-2. The resolution WRAL uses to go to air is 1280 x 1080/60i.
Data rates from 25 Mbps to 50 Mbps were evaluated to determine the point at which artifacts were no longer noticeable. The source video for the test was made up of high-motion detailed images originated in DVCPRO 100 format. The video included nature scenes with flocks of birds flying over water, hockey games with the cameras panning through the crowds and night scenes with flashing lights of emergency vehicles. All these scenes were chosen to test the worst-case scenario and visually measure the encoder’s performance.
The WRAL engineering team scrutinized the video simultaneously on four different display technologies. The first was a 42-inch plasma monitor, the second a 19-inch Ikegami HD CRT broadcast monitor, the third a Dell 20.1-inch 16:9 1680 x 1050 LCD display using a Black Magic HD Link to convert HD-SDI to DVI and the fourth was a Samsung Consumer 32-inch HD CRT monitor using HD-SDI converted to component. All the formats evaluated were 1080/60i. The low data rate format at 25 Mbps utilized an HDV codec while all other formats were MPEG-2 1080i.
The source video directly from the tape at 100 Mbps I-Frame-only was the standard to compare to. Why not start with HDCAM, D-5 or uncompressed? Anything can be proven in math, however, in the real world at WRAL, everything starts on 100 Mbps tape. Because ENG crews never capture in the field in other formats, any other source format was irrelevant.
The WRAL engineering and news teams found only slight differences when looking at 100 Mbps video from the source tapes and 37.5 Mbps Long GOP MPEG-2 encoded from the Edius editor. They felt that the differences were not discernable enough to forgo the advantages. Audio is embedded during the MPEG-2 encode process, which simplifies file management and ensures lip sync when editing. Analog ingest of satellite feeds with resulting SD files can be mixed on the timeline. They can be set up with sidebars or cropped top and bottom depending on the subject matter.
REPURPOSING OF CONTENT
WRAL, like many other broadcasters, has been challenged to change the single-stream paradigm of local television. In addition to WRAL’s CBS affiliation, the station provides programming of local content for a 24-hour news channel, a 24-hour weather channel, newscasts for its sister station (a Fox affiliate), the website (WRAL.com) and a content service for mobile devices. Therefore, any new content management system installed at WRAL must assist news and other content creators in repurposing original content on WRAL and CBC’s multiple streams.
A key requirement to enable repurposing of content is a nonproprietary workflow. The broadcast HD MPEG-2 files can be automatically converted to multiple streams of video in appropriate formats for multiple delivery paths. WRAL utilizes a transcode server powered by Canopus’ ProCoder software, which is integrated into the all-digital workflow.
CONCLUSION
The reason WRAL is an early pioneer in HD is because of CBC’s belief in providing nothing but the best quality for their viewers. Because of a nonproprietary file-based workflow, WRAL is able to do a lot more to extend their brand and give more to their viewers without growing the newsroom. WRAL is becoming a production engine for a variety of formats and venues, not just a television news station. The file-based workflow gives the WRAL viewers both quantity and quality without adding additional resources.
Peter Sockett is Chief Engineer at WRAL and Fred Fourcher is CEO for BitCentral.
