Tape machines
Mar 1, 2009 12:00 PM, By John Luff
The first practical (i.e. commercially viable) electronic recordings for television were shown more than 50 years ago at NAB in 1956. Later that year, CBS became the first user when “Douglas Edwards with the news” was delayed for rebroadcast on the West Coast. We have come a long way in 53 years. Though it is clear that videotape was one of the most influential inventions in our business, it was just in 2005 that the National Academy of Television Arts and Sciences awarded a lifetime achievement award to the engineering team that paved the way for this important development.
A 90-minute reel of quad tape weighs about 30lb, whereas a DV tape weighs only a fraction of that. Quad tape photo courtesy LabGuy’s World.
Though the importance of video recording on moving media has diminished, it is clear that there is a long way to go before videotape is dead. The demise of videotape has been predicted for many years, however, based in no small measure on the increasing importance of new methods of recording to static memory, optical media and disk drives. These alternative media have found niches in the industry, including in consumer recorders.
Volumetrically, videotape is still incredibly efficient. A standard equipment rack might hold a few tens or perhaps a hundred terabytes. In terms of storing complete television programs, only recently could a rack of spinning disks hold as much content as the same volume of readily available DV videotapes. While not exactly shocking, it points out that videotape on shelves, which is a green method of storing content, competes well with arguably more modern methods that consume kilowatts of power.
Identifying a professional video recorder
Increasingly, our industry relies on advances in recording technology from consumer electronics research. I don't think it is in dispute that the DVC PRO format, which clearly had a large impact on news acquisition, would not have been introduced if most of the development cost had not been shared with consumer products. Over time, many of the DV-based camcorders that found their way into news departments worldwide were modified consumer products.
To me that begs the question: What constitutes a professional video recorder these days? Though a definitive answer to such a broad question is impossible, the answer is partly features and partly performance. In considering performance, I choose to speak only of digital recorders, as analog recording is both hard to find and not appropriate given the state of the art today.
High-end modern video recorders can record 880Mb/s. Such high bit rates are obviously suited to high-quality mastering for digital cinema and high-end production. Other common bit rates used today are based on the DV 25Mb/s standard, for both HD and SD content. Advances in compression technology have increased the quality of recorded content to such an extent that you can't simply look at the bit rate and extrapolate relative quality. For example, it's impossible to compare MPEG-2 at 25Mb/s (long GOP) and AVC coding at 25Mb/s (AVC Intra); they are not equal. The improvements in codecs are such that 25Mb/s AVC content compares favorably with a considerably higher data rate for long GOP MPEG-2.
Other formats abound. JPEG 2000 is in use for digital cinema and broadcast. At high bit rates, suitable for mezzanine recording formats for high-quality use in studio production and backhaul, JPEG 2000 offers excellent results in multigeneration performance. Recorders in commercial use for JPEG 2000 are not videotape at this time, but rather IT standard recording media.
Size-wise
It is interesting to look at the evolution of videotape in a second dimension, or more correctly in several more dimensions: weight, thickness, width and length (of tape). A 90-minute reel of quad tape weighs about 30lb. In contrast, an 83-minute DV tape weighs only a few percent of that. Not surprisingly, it is also only a few percent of the volume. While quad tape is fully 2in across, DV tape is only 6.35mm across (12 percent of quad tape's dimension). No one who has seen pictures from both eras would disagree that for a fraction of the cost, weight and volume, DV produces a vastly superior picture. I'm not surprised because I remember changing tubes in Ampex VR-1000A recorders from the late 1950s. Refurbishing recording heads on a quad recorder cost more 20 years ago (even in uninflated dollars) than a new professional DV recorder that produces superior quality.
Unvideotape
I have not yet discussed “unvideotape,” which is my favorite name for data tapes used to archive video content. I think I can make the argument that LTO and other data formats are lossless videotapes. In the future, we will certainly find a huge uptake in data tape storage of video content. Robotic libraries can hold thousands of hours of content in the same volume the VR-1000A of my previous life represented. Ironically, I enjoy robotic video transports of the 1970s. They are more reliable and eat tapes less often. They also facilitate the long-term preservation of content that video recorders cannot be relied upon to do.
Signs point to an end
No one can predict when videotape will disappear. But the signs pointing to the elimination of tape are everywhere. Recently, the last plant duplicating VHS went offline. Fortunately for all of the news operations that depend on DVC PRO and DVCAM, the same media is used in ubiquitous consumer recorders, which provides a bit of insurance. When it ceases to be profitable for manufacturers to supply consumers, I bet that all professional uses of videotape will feel the threat.
John Luff is a broadcast technology consultant.
Send questions and comments to: john.luff@penton.com
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