Goodbye to the universal format?

Digital video recording formats based on the DVC standard tend to elicit mixed reactions. Many users disqualify them for the size of the tape, which makes them prone to dropout problems and lack of stability in playback.

Many others complain about the problems of tape interchangeability, which are also directly related to the physical size of tapes and mechanisms. Some claim that bandwidth and 4:1:1 sampling are simply not enough for truly professional applications. And others, more simply, are limited to renewing their analog equipment, waiting for the waters to clear up.

In the current state of technology even domestic DV equipment can be considered as a viable option for the registration of material destined for broadcasting, and the additional features of robustness, sound handling and image quality of professional formats make them really attractive options.

However, it must also be admitted that mechanical problems exist, and that with the exception of recordings made in DVCPRO-50, DV-encoded material does not withstand the chroma-key test: Compression is really excessive for critical applications in post-production. But as long as it is not about making sequences of effects, the image has nothing to envy to the Betacam SP.

The wide range of recording formats makes it clear that a future very different from what we are used to awaits: The selection of the right format for each operation is more a problem of equipment specifications than of compatibility or dominance of a particular format.

Everyone will operate "at home" with the format that is most convenient for them, leaving aside the massive movements of the market. In fact, at this point it is clear that the exchange format of the coming years will be the Betacam SP, as the installed equipment will continue to be used while the market evolves towards a high specialization of the equipment used for each application.

While Panasonic's sophisticated D1 transports and D5 recorders retain their place in the most sophisticated post-production and effects making applications, Sony's Digital Betacam format has established itself as the most widely used high-quality recording medium in mainstream applications.

Its performance has ensured high market penetration, and for now offers a clear route for migration to 16:9 production and standard resolution digital television (SDTV). The robust Digital Betacam machines are at ease both next to the most sophisticated composition systems and in telecine applications and in online editing rooms or high-profile mobile units.

Another alternative offered by Sony is the Betacam SX format, which although it is presented as a line of products especially aimed at news production, can work very well as a direct replacement for Betacam SP equipment. In fact, Betacam SX transports can be inserted completely transparently into any linear or non-linear system that uses analog equipment.

In addition to conventional video recorders, Sony's offering includes a portable linear editor, a VTR that doubles as a hybrid editing system, and pre-read editing machines. These devices use the same type of cassettes as SP recorders, and some models can even play analog recordings of Betacam SP tapes. Additionally, SX recording equipment can be integrated with existing analog cameras, allowing a gradual migration to the new format.

Betacam SX products record MPEG-2 digital video, which allows them to obtain very good image quality with relatively low bandwidth. Sony managed to implement a brilliant solution to convert continuous streams of MPEG video into editable material, which allows it to use the same digital video format for recording and playback on recorders, hard drives and transmission on local networks, taking full advantage of the benefits of temporal compression. In addition, it has the advantage of being able to handle two or four fully editable audio channels.

It should be noted that compression defects become visible in especially critical applications (such as images with very fast movements and a lot of detail). However, the format has the advantages of 4:2:2 processing, including better apparent resolution and better response when using its signals in analog environments.

Sony proposes the integration of production systems where the video is compressed only once, and handled completely transparently until its final delivery. In fact, the material recorded on Betacam SX machines can be edited, stored on small servers or playback systems and even transmitted over satellite links while always retaining the original encoding and compression. Being able to enjoy these advantages implies, at least for now, maintaining total brand loyalty.

JVC introduced the Digital-S format three years ago, which uses 1/2" tapes in VHS-type boxes, to record 4:2:2 digital video with a compression of 3.3 to 1 and two or four channels of excellent quality and fully editable audio.

Digital-S is a conventional recording format, and the equipment offers the possibility of integrating into existing facilities without any inconvenience. Considering that the bandwidth of Digital-S is 50 MBb/s, exactly double that of DV formats, it is not surprising that it offers images of excellent quality.

In principle, these recorders are designed to communicate with other equipment using analog or SDI signals. In other words, they are not in themselves an integral part of a connectivity solution.

Although some specialists object to the apparent resolution of the images, the truth is that this format is successfully positioning itself as an alternative to replace Sp Betacam equipment in existing facilities, and even competes successfully with the Digital Betacam in the European market.

The cost/benefit ratio of JVCs is excellent, as it is possible to acquire digital equipment of excellent performance with investments similar to those required by Betacam SP recorders of the "industrial" type. The use of Digital-S in the production of 480p material would not offer any difficulties, and JVC representatives have occasionally mentioned the possibility of modifying the equipment to operate in 720p.

At NAB'98 prototypes of a format known as Digital-S 100 were presented, equipment that based on the same platform offers a performance of 100 MB / s and that were demonstrated handling HDTV signals of type 1920i. This variation of the format constitutes a reasonable route for the migration towards the recording of high definition signals, although its standardization is yet to be defined.

For its part, Panasonic also presented last year prototypes of the DVCPRO 100 format, which is an integral part of its proposal for the production of high definition signals in 1080i format.

Although the performance of this system is very attractive, its compression scale and architecture are also to be defined, as in the case of Digital-S 100. Panasonic's proposal is based on the use of four DV encoders in parallel and the same platform as the DVCPRO and DVCPRO 50 equipment.

Some people believe that it is not possible to make reliable recordings on 6mm tape with such a high density, but if the performance of DVCPRO 50 equipment serves as an indicator of this parameter, it is possible that Panasonic will achieve a viable format with a very high density and great operating comfort.

This offer complements the well-known D5 equipment, which offers the best possible image quality for PAL or NTSC productions without compression and which, with some modifications, supports the recording of high definition images with a very reasonable level of compression.

After this brief review, a restlessness appears. The positioning of the existing formats at the moment is reasonably clear, although the pressure of the industry to segment the market and end the notion of the "universal" format, which was the dubious privilege that it enjoyed in Betacam SP for many years, is already evident. However, the high-level market offering has not been standardized around a single signal encoding format.

In the next two years it will be defined if the native format of the 100MB/s recorders will be one of the DTV standards or if each one will record in its own video system that must then be converted into the television format that is most convenient for its dissemination.

Let's not forget that the DTV streams that will reach home TVs will be MPEG-2 sequences, and that the leading companies in the area of signal distribution, with Tektronix at the head, have proposed a model in which MPEG-2 encoding should only be applied for storage and final distribution.

In short, the transports and recorders for the next era of DTV already exist, but it remains to be defined what their inputs and outputs will be. This is another part of the most difficult decision in recent years, which most producers have decided to handle in a Solomonic way: postponing it.