NAB Replay - Digital acquisition
There is a digital revolution taking place in the world of television broadcasting. At NAB 2003 there was a buzz in the air, created by the realization that the relentless growth in digital processing and data storage capabilities has now turned the video industry on its head.
While the rest of the world is going digital and nonlinear, the video workflow for many stations remains analog and linear. For those who have moved on to linear tape-based formats such as DVCPRO, DVCam, Digital BetaCam, Betacam SX and IMX, the workflow is little more than the digitized version of the legacy analog workflow.
The prototype camcorder shown by Panasonic at NAB will allow the use of up to four PCMCIA modules. These modules can be plugged into the PCMCIA slot of notebook computers where the files can be transferred or edited directly.
Meanwhile, the revolution in computer-based tools for image synthesis, composition and video editing launched a new paradigm in which audio and video streams are treated as data. These tools deal with video and audio as files that can be accessed randomly, shared across digital networks, and manipulated to create traditional linear audio and video programs. These tools are also being used to create new forms of digital media content that give the viewer more control and the programmer the ability to localize, even personalize, the presentation.
For more than a decade we have been told that a tapeless digital workflow was right around the corner. Yet the death of videotape has appeared to be just as remote a possibility as the end of analog television broadcasting scheduled for Dec. 31, 2006. However, at NAB 2003, it became a distinct possibility that broadcasters may be acquiring images without tape by 2006.
In February, Sony pre-announced a major shift in its strategy for video acquisition and production to be introduced at NAB. This strategy is optimized for the new digital workflow, treating video, audio and related metatdata as digital media files. The product family is based on optical disc recording using the new Blue Laser technology being developed by Sony and other consumer electronics companies. The 12-centimeter optical discs can store 23.3GB of data and offer random access to the recorded files.
At NAB, Panasonic unveiled its plans to move directly to a solid-state camera design for video acquisition, based on the recording of data to Panasonic's SD memory cards.
Meanwhile, products that enable acquisition and archiving directly to magnetic hard disks proliferated at NAB.
With the introduction of its optical disc-based product family, Sony has embraced the new digital workflow and a variety of existing and emerging standards for connectivity, video compression and metadata. Two camcorder models offer a choice of compression codecs for recording. The PDW-510 DVCAM camcorder supports 4:1:1 DVCam at 25Mb/s; the PDW-530 MPEG IMX/DVCAM supports both DVCam and IMX (MPEG-2 4:2:2) at 30-, 40- or 50Mb/s. Both cameras can support 50i/25p (625 line) and 59.94i/29.97p (525 line) formats. An optional card will allow the camcorders to capture images at 23.97p/25p for digital cinematography applications.
In addition, both camcorders allow a low-resolution MPEG-4 proxy stream to be recorded simultaneously; this stream can be used both in the production and archival aspects of the digital workflow. The camera also records separate head frame images and a variety of metadata about the captured images; it is capable of searching imagery already captured to disc and recording metadata produced by field editing systems onto the disk with the essence media.
The system components support both the IEEE-1394 and Ethernet interfaces for transferring assets as Material eXchange Format (MXF) files and are also capable of remote management via Simple Network Management Protocol (SNMP) over IP networks.
Panasonic's decision to move directly to a solid-state memory design for image acquisition may indicate what it perceives as significant limitations of optical recording technology. These concerns are centered on operational limitations related to environmental issues and the data transfer rates for files recorded on the optical discs.
Blue Laser discs will be housed in a shuttered carrier, similar to removable floppy and hard disks. The reduced track size makes the discs more vulnerable to environmental contamination, especially dust particles. And like magnetic hard disks, optical drives are sensitive to shock and gyroscopic errors. In the new Sony camcorders the optical drive assembly is isolated on foam shock mounts. The optical recording process requires that the media be heated in order to effect a phase change to record the data. Sony specifies the operating range for the new camcorders at 32 degrees Fahrenheit to 104 degrees Fahrenheit. But there are concerns that power consumption may increase significantly below 40 degrees Fahrenheit, affecting the duration of recording on a battery charge. These issues do not affect workflow; however, they may influence applications for optical recording, especially in demanding ENG environments.
The data transfer rates that can be achieved with optical media, however, have a significant impact on workflow and may limit the use of optical recording for high-definition image acquisition. The write speed for the consumer version of Blue Laser recorders will be 36Mb/s; this is inadequate to support the higher data rates needed for the higher quality IMX formats. To address this limitation the optical drives that Sony developed for this product family support a write speed of 72Mb/s; this is adequate to support all of the available formats, but insufficient to support the write speeds needed for a future HD version without heavy compression. The studio decks use two optical head assemblies to support transfer rates of 144Mb/s.
The camcorders and battery-powered mobile player can transfer DV25 files at 2.25x realtime and IMX files at 1.25x for 50Mb/s files to 2x for 30Mb/s files. Proxy files can be transferred at 30x real time. The studio decks can transfer DV25 files at 5x real time and IMX files at speeds between 2.5x and 4x; proxy files can be transferred at 50x real time.
Panasonic espouses the advantages of solid-state camcorders in dealing with both the environmental and transfer speed issues. A solid-state design will allow the development of camcorders that operate over a much wider range of temperatures and environmental conditions. They also noted that the elimination of the bulky drive mechanism has the potential to enable radical changes in the physical packaging of camcorders, significantly reducing their weight, size and power consumption.
Like other memory devices, SD memory cards support high read/write speeds. Panasonic has developed PCMCIA card modules with four embedded SD memory cards. These modules will support a data transfer speed of 640Mb/s; 20x real time for 4:1:1 DVCPRO25 and 10x for 4:2:2 DVCPRO50. This transfer speed will also support future HD camcorder products. First-generation PCMCIA modules will use four 1GB SD memory cards, supporting a record time of 18 minutes for DVCPRO25. The prototype camcorder shown by Panasonic at NAB will allow the use of up to four PCMCIA modules. These modules can be plugged into the PCMCIA slot of notebook computers where the files can be transferred or edited directly.
One limitation of solid-state memory is that it is too expensive for archival purposes. For first-generation products, the media cost per minute will be relatively high compared to other acquisition media. But the SD memory cards are riding the Moore's Law curve; over the next five years storage densities will increase to 4GB per card, then 16GB. And all of the products that use SD memory storage will be able to take advantage of the higher density cards as they become available.
Sony has indicated that they will migrate to solid-state memory for acquisition products as the cost of the media becomes practical. This raises the issue of whether optical storage for acquisition will have a relatively short window of opportunity. And it raises the specter of another competitive threat to the companies that now dominate sales of acquisition gear to broadcasters.
Memory cards are one of the core technologies enabling the revolution in digital photography. Most of the new digital cameras from the traditional photographic vendors like Canon, Fuji, Olympus and Nikon already offer still image resolutions that are higher than HDTV acquisition gear. And most of these cameras support the capture of short clips of low-resolution video as well. It is just a matter of time until digital photography and HDTV acquisition collide. By the end of this decade, the chips needed to build a high-resolution still/video acquisition system will become commodities; at that point the core competencies for these products will be the lens and the packaging.
Hard (disk) realities
Over the past few years there has been another quiet revolution in digital workflow. That revolution has been driven by the incredible increases in storage capacity and transfer speeds for hard disk drives.
A year ago, Thomson introduced the Viper FilmStream digital cinematography camera. This flexible camera system has the ability to output uncompressed RGB data via two 1.5Gb/s SMPTE 292M connections. Director's Friend stepped up to the opportunity to capture this avalanche of bits directly to their HDreel hard disk arrays, now available only through rental arrangements. Many companies took notice.
This year, new hard disk-based digital cinema and HD recording systems proliferated like MP3 files. The new product introductions include: Accom's WSD/HDi, BayTech Cinema's CineRAM, BOXX Technology's CineBOXX, DVS's CineControl/CineReel, Kei Soku's UDR-2E (seen with the Thomson Grass Valley Viper camera) and S.two's D.Mag (found in the back of an SUV).
Focus Enhancements and JVC teamed up to integrate disk-recording performance with the camcorder. The FireStore DR-DV5000 can be mounted directly to JVC full-size DV camcorders for simultaneous recording to tape and disk. The FireStore FS-1 allows recording direct to disk via a Firewire interconnect; Sony offers a similar product, the DSRDU1 DVCAM video disk unit. The FireStore FS-2 is a studio VCR replacement with Firewire I/O as well as analog composite, S-video and analog component I/O, which is converted to DV 25 for recording.
Craig Birkmaier is a technology consultant at Pcube Labs, and hosts and moderates the OpenDTV Forum.
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