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Building A Better NLE Realtime Editing For The New Millenium

This past year the DV format has become as the preferred format for nonlinear video editing. This came about for several reasons: the increasing sales of DV camcorders with IEEE 1394 (i.LINK) interfaces from major camera manufactures, and the increased performance of PCs, with faster CPUs and larger/faster hard disks. By using the IEEE 1394 DV connector to import data directly to the PC from the camcorder and back again after editing, editors can now create a high-quality master tape, with the lowest amount of data loss, quickly and economically. The DV format has brought the productivity of nonlinear video editing to an all time high for professional videographers.

In 2000, real-time editing will bring even more value to video professionals. The increased speed of real-time editing systems will let editors spend less time editing, and more time on the creative aspects of their video production. With basic editing commands played out in real-time (without any rendering), fine-tuning of the video will become easier, allowing editors to quickly view and evaluate their productions during the editing process. And because basic editing will take less time, editors can use more complex editing techniques that might require some processing time, to improve the overall quality of their production. Video professionals who have already shifted to well-designed real-time NLE systems from rendering NLE system have recognized these merits.

With all this talk about the benefits of real-time, I would like to address some important points to consider when evaluating real-time NLE systems.

First, a real-time system has to improve productivity significantly.
For this, real-time capabilities should be applied to the editing functions that are used most to shorten the overall time required when capturing, editing, and outputting to DV tape. Since editors need to check the image quality of edited footage during editing in the same quality as the final video out (to DV), real-time DV output must be supported. Systems that require rendering before DV-out are not acceptable, because often editors need to adjust the image after they see the final DV out. They know that some changes in the image (quality, title display area) might be detected only after the video has been rendered or encoded to DV. Unless they wish to output the final image only in analog format, real-time output to DV is necessary.

It is obvious that functions like dissolve, or titling, which editors use frequently, must be processed in real-time.
Most real-time systems claim that they can output 2D transitions or titles in real-time, but when you put them together, such as placing a title over a transition, many require rendering. This is a big limitation. For example, if the editor wants to put a copyright watermark on the video from the beginning to end, and if it needs to be rendered when it overlaps transitions and other titles, this can take many hours. You can hardly call a system that requires so much rendering "real-time."

Image adjustments (color correction) should also be processed in real-time.
Usually, adjusting the images in DV systems is a very difficult process. When editors need to adjust the brightness or white balance for all the footage in a production each clip has to be rendered. This takes a very long time, even with today’s powerful PC systems. These are just a few examples of common editing functions that need to be processed in real-time for a system to be truly real-time. They are much more important than, for example, 3D transitions that editors rarely use. Although there are immense technical challenges in designing real-time systems, these editing capabilities must be included -- based on what users need not what the hardware can easily provide. Of course, stability is another important factor of productivity. Editors can accurately estimate editing time only with a stable and reliable system.

The second crucial element of real-time editing is maintaining image quality.
Some real-time systems sacrifice quality to achieve real-time speed, such as rendering only one field per frame, or not using anti-aliasing on titles, or by using low-cost video encoders made for game machines for analog real-time output. Professional video editors will not accept these schemes.

The quality of the DV CODEC itself is also important. If the DV CODEC used is not fully tested and turns out to be non-compliant with existing DV decks and camcorders, the final output will show artifacts that are unacceptable. Internal real-time rendering processes should be done in YUV, preferably YUV 4:2:2, which stays true to the original video. Many systems use the RGB color space instead because it’s simpler and cheaper to build into the system, but it doesn’t maintain image quality as well. This is particularly noticeable with bright colors. The main reason for using DV format is because of its high image quality. A real-time system that cannot maintain this quality is useless for professional editors.

The third point to consider when choosing a real-time system is its upgrade capabilities.
CPU speeds are doubling every year. This increase in CPU power should be used for more complicated and sophisticated real-time editing processes. Real-time editing boards in many NLE systems have expensive DSP chips on board, which may be fast when they first hit the market, but are unable to take advantage of faster CPUs as they become available, and are quickly outmoded. Only systems that are specifically designed to use CPU power can utilize it very well. The best real-time systems require only software updates to add new features, and can continue to upgrade together with CPU clock-ups and new signal processing commands. This extends the life of the NLE system and gives editors a much higher return on their original investment. In the future, the popularity of the DV format will continue to soar along with technical advancements in related equipment. DV camcorders will upgrade from 4:1:1 to 4:2:2 for better image quality, NLE systems will be required to support HDTV format, and DVD is fast becoming a leading format for final distribution. And let’s not overlook the importance and growing popularity of Web-based video streaming distribution.

Video editing software will also change its specification, in response to new demands. Linear editing systems will be replaced by NLE systems very quickly on a worldwide basis, and the editing process will become entirely digital in many areas, such as DVD authoring. The highest barrier for switching to NLE will be in the learning process of editing software. The need for simple yet productive editing software will become greater. Compositing software will become more sophisticated and require less processing time. Several DVD authoring systems supporting CD-R disks were introduced recently, but still need more time to mature, since we have a very wide range of PCs to support software playback. Easy-to-use DVD-compliant authoring and playback systems are needed, but because of the delay in the unification of the DVD-R, DVD-RW, and DVD-RAM formats, there are still difficulties to be worked out in this area.

In 2000, the real-time NLE systems that will succeed will have to be flexible. They will succeed only if they significantly reduce editing time, if the hardware is designed to take advantage of the CPUs escalating power, and the software is upgraded continually to support the changing market requirements. This ideal system will not be made possible by the effort of only one company. The solution will have to be the result of a collaboration of hardware and software companies

Well said Hiro! We could not agree more! And no product is a better example of what a real-time system should be then the MEGAREX!!!

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