Configuring a DV Workstation
Posted Apr 20, 2005

Like most technology writers, I frequently receive emails from readers with comments, questions, or both. One fairly consistent question is which equipment to purchase to streamline their capture, editing, and authoring tasks. Issues range from the benefit of dual vs. single processors, how additional RAM will impact performance, and what type of disk capacity to buy. Rather than continue to answer these questions piecemeal, I'll explore all these issues and more—for those on the Windows side (for the sake of effective, direct comparison)—in this article.

To provide structure for the discussion, I'll refer to a recent project of mine that's fairly typical of the event video work that I do. The performer was Taimo Toomast, an opera singer from Estonia, and the event was his performance in a neighboring town last December. I shot the concert with two cameras and delivered finished DVDs to Toomast and the concert promoter.

The concert had two sets, each about 45 minutes long. I changed tapes during the intermission, so before editing, I had to capture three hours of video from four separate tapes.

As with many concerts, the actual editing was fairly minimal; I used Liquid Edition's Multicam interface Figure 1 to synchronize Cameras A and B, and cut from camera to camera, consolidating each set into one 45-minute clip. I had to color-correct both clips to make the colors appear consistent, add some titles and credits, and I was ready to start authoring.

Recognizing that the type of effects used to produce the concert is not representative of most wedding and other projects, I built a three-minute test project from the same footage to compare the performance of the RAM and processor configurations presented below. This test project included chromakey, color correction, still-image pan and zoom, picture-in-picture, 2D motion within the video file, and slow motion. I ran the test project through three programs—Adobe Premiere 1.5, Pinnacle Edition 6, and Sony Vegas 5— for a broader assessment of the benefits of upgrading CPU and RAM.

With all programs, I rendered this project twice to test RAM and CPU performance: first, into DV format, representing the time it would take to preview the project; and second, into MPEG-2, which of course indicates the time to render for DVD production. Then I multiplied the results by 30 to scale rendering times up to the actual 90-minute project.

To analyze the savings produced by a faster DVD recorder, I assumed that I would have to burn the final project five times, one to keep and four to give to the artist and promoter. I burned the project to DVD using Adobe Encore 1.5.

Since the advent of DV, capture has been a real-time procedure, so capturing my 180 minutes of source video would take 180 minutes, plus setup time. The only way to shorten this is by using a digital disk recorder (DDR)—essentially a hard drive attached to your camcorder—while shooting. Then, instead of capturing the video traditionally from tape, you connect the DDR to your computer via FireWire, where it looks like another hard disk, and drag the video files from the DDR to your main editing drive. For more information on DDR operation and products, check out Stephen F. Nathans' and David Doering's

To test the time savings produced by DDRs, we captured one hour of video with nNovia's QuickCapture A2D Figure 2 which, as the name suggests, can capture video from both analog and DV camcorders. Then we dragged the video from the DDR to our main capture drive, which took 11 minutes, a savings of 49 minutes over real-time capture, or 147 minutes for three hours of video.

Though the savings-per-hour-saved yielded by the DDR (as shown in Table 1) come with high up-front costs, consider that the QuickCapture unit and others like it also provide a backup copy of your video in the event of tape failure. During shooting, you can access your captured video on a DDR much more quickly than you can from tape, so in certain situations you can check your shots while you still have time to reshoot.

In addition, these units save wear and tear on your camcorder during capture since you're no longer using the camcorder to play the video. (You could also use a dedicated capture deck, but of course there's an equipment investment involved with that approach as well.) In a pinch, you can edit directly from the DDR when attached to your computer, eliminating the transfer time totally, though most users will likely prefer to drag the video to their main drives and edit from there. Note that less expensive DDRs are coming, though most without QuickCapture's high-quality analog-to-digital capture capability.

Central Processing Unit (CPU)
Once the video is captured to disk, it's time to start editing, where the speed of your computer's central processing unit, or CPU, becomes paramount. When considering a new system, note that upgrading your CPU can deliver three potentially complementary mechanisms to accelerate project preview and rendering.

First is CPU speed, which is represented in Gigahertz or GHz, or millions of operations per second. Simply stated, a 3.6GHz processor can perform twice as many operations per second as a 1.8GHz processor. All other things being equal, this generally translates to twice the performance, so your rendering times should drop by roughly 50%. (Of course, the real-life comparison never adds up so cleanly, which is why you have to test it.)

The next way to boost performance is to purchase a processor with Hyperthreading (HT) Technology. At a high level, processors with HT Technology can perform two logical operations simultaneously, but still can perform only one execution operation at a time. To explain, assume that a processor is a widget stamper on an assembly line. The widget stamper itself can stamp X widgets per hour—this is the execution engine. Feeding the widgets into the stamper is an assembly-line worker, which is the logical operation. If the assembly-line worker takes a break to scratch his nose or chat with his neighbor, having an extra assembly-line worker to feed widgets to the stamper boosts overall production. Even adding the extra worker, however, you'll still never produce more than X widgets per hour. Similarly, adding the additional logical operation makes the processor more efficient, but not truly faster.

In addition, programs must be rewritten to benefit from HT Technology. If the original program was highly efficient, HT Technology may provide little benefit. Like any other coding, some rewrites for HT Technology are done better than others, so may produce variable benefits. The bottom line is that you can't expect HT Technology to double your performance, and in some instances, performance boosts may be quite modest.

The third way to increase performance is by installing two processors, each of which can have HT Technology, which together look like four processors to Windows. Here you've installed an additional stamping machine, which theoretically should double performance. Again, however, application developers must modify their programs to benefit from dual processors, and performance gains vary widely by program.

To test the benefit of HT Technology and dual pro- cessors, we used a dual 3.6GHz Xeon Dell Precision 670 workstation Figure 3. In the system setup, we configured and tested the system in three different ways: as a single processor without HT Technology, as a single processor with HT Technology, and as a dual-processor system with HT Technology. We ran all configurations with 1GB of system RAM.

We tested preview and rendering with three different programs—Adobe Premiere Pro, Pinnacle Edition, and Sony Vegas—with the results presented in Figure 4 Note that the times for Premiere Pro and Vegas include both rendering to DV (for preview) and output to MPEG-2, while Edition's time includes only MPEG-2 rendering. This is because Edition previews in the output format (in this case MPEG-2), and doesn't need to render to DV. The results in the table are presented in hours.

Table 2 shows the cost per hour saved by a dual-processor system over a system with HT Technology. We used Vegas for this calculation as a best-case scenario, since the faster configuration shaved the most rendering time of the three programs. Note that you can no longer buy a workstation-class PC without HT Technology, so we couldn't compute the cost per hour saved for HT over a system without HT.

Much like the way one-time Montreal Expos skipper Dick Williams famously characterized his job, GHz never has an off day. That is, while faster processors will improve all applications run on the computer, the benefit of multiple processors is very application-dependent. In this regard, it's not surprising that you can purchase a dual-processor 2.8GHz system from Dell for $2,911, about $500 less than a single-processor 3.6GHz system ($3,412). That's because in most applications, the faster, single-processor system should outperform the slower, dual-processor system.

Random Access Memory (RAM)
To test the benefit of additional RAM on system performance, we used a startup script to configure the Precision 670 with various amounts of RAM, including 256MB, 512MB, and 1GB for the single processor-with-HT Technology test case using a single SATA drive. While running these tests for all editors, we also had Adobe Photoshop and Internet Explorer open to increase memory usage. Figure 4 shows the results of our performance trials for the single processor-with-HT Technology configuration.

As Figure 5 illustrates, the benefits of additional RAM are quite modest, at least on this configuration. This makes sense for two reasons. First, neither preview nor encoding works in close-to-real time, which usually means that the performance bottleneck is processing, not data retrieval. Second, the SATA drive was capable of very high read rates (see "Hard Disk Drives" section), further ensuring that data retrieval wouldn't create a bottleneck.

Once again, as Table 3 shows, since the minimum Dell workstation configuration is 512MB, we can't calculate the cost per hour saved for the jump between 256MB and 512MB. Looking at the best case, Premiere Pro, and the jump from 512MB to 1GB, we find a cost per-hour-saved of $842, the worst of the review.

If you're buying a new computer for digital video work, note that while running the respective editors and other open applications, none of the test cases consumed more than 671MB of RAM. Given the relatively modest cost of jumping from 512MB to 1GB, this may make sense. However, spending another $380 to get to 2GB clearly isn't warranted.

Also note that while rendering isn't a real-time event, these results would likely change if you were to use the computer for presentations, especially if they involve video playback. For example, during presentations and seminars, I often open PowerPoint, a video editor like Premiere Pro, and media players like Real, QuickTime, and Windows Media.

During recent presentations, on two separate 500MB systems—one an HP desktop, the other a Dell laptop—video playback often suffered and PowerPoint became unstable. Checking the performance tab of the Windows Task Manager (click Ctrl+Alt+Delete), I noticed that RAM application usage exceeded the amount of installed RAM, which forced the system to store the excess to disk. In both cases, installing an additional 512MB RAM improved performance and stability. So, if you'll be using the computer for both presentations and production, additional RAM may pay dividends there.

Hard Disk Drives
If you're producing video, hard disk space is a necessity, and no matter how much you have, it never seems like enough. Fortunately, hard disk prices have continued to drop precipitously, so there's no shortage of inexpensive disk capacity. But not all hard drives are created equal, and capacity is only one differentiating factor. Instead of buying lots of capacity at a low cost, you can spend lots of dough and get much faster disk space at a much higher cost per gigabyte. The obvious questions are how much extra do these high-speed drives cost, and how does the extra speed impact rendering performance.

As shown in Table 4, the extra speed costs quite a lot. Specifically, the Seagate UltraSCSI 320 Cheetah costs $4.94/GB, while adding another Serial ATA drive to the system costs just $.91/GB. Both external FireWire drives came out at just under $1/GB (all prices except LaCie, which is direct).

As you can see, the UltraSCSI did deliver some time savings over the Serial ATA in rendering MPEG-2 files, but not substantial. Given what we know about the process, this isn't surprising, since all drives easily read more than nine times the bandwidth of a single DV file (3.6MB/sec), which is plenty of overhead during rendering. This is reflected in the Read/Write numbers shown in Table 3, as measured by Pinnacle Studio's capture utility.

To be clear, if the computer encoded into MPEG-2 format in real time, it would require at most 7.2MB/sec of data, and then only when rendering a picture-in-picture effect, which involves two simultaneous video streams. Even with dual processors running, in the fastest disk configuration, Premiere produced our 90-minute video in just over three hours, or roughly 34% of real time. When rendering the picture-in-picture effect, Premiere had to retrieve only about 2.4MB/sec, clearly within the read capacity of all drives.

Obviously, in ultra-high capacity applications like video servers, the UltraSCSI drive's extra capacity would pay off in spades. In a CPU-limited application like rendering that uses about 5% of the maximum write capacity, UltraSCSI's performance benefit is minimal. These drives make sense only for the most time-critical video production environments. Clearly, however, for most other producers, loading up on Serial ATA drives makes the most sense.

Note that while the LaCie Bigger Disk Figure 6 can connect via FireWire 800 in addition to FireWire 400, we didn't have a FireWire 800 adapter so couldn't test in this configuration. Even connected via FireWire 400, the Bigger Disk's reasonable production times and the inherent ease of installation of an external unit make it a very attractive option. I must admit that the concept of 1TB of storage is extraordinarily liberating, though I'm sure all that space will disappear as I start adding more multi-camera projects. Finally, though you can use the Maxtor drive for production, the sheer portability of the book-sized drive makes it the most attractive for backup.

DVD Burner
If you haven't upgraded your DVD recently, a faster DVD recorder represents the least expensive option for boosting production time. To test recording time, we burned DVDs from Adobe Encore in the single processor with HT configuration with 1GB of RAM, burning to an HP 2.4X drive and the new NEC 16X ND-3500A drive Figure 7, which recorded at a blistering 16X using newly certified Verbatim media. (At this writing, 8X media is much more common than 16X media. You can write at 12X and 16X speeds to 8X media, but both the drive and burning software have to support it. That said, 8X recording is probably the most reliable strategy with 8X media, and you'll probably never miss the 2-4-minute advantage of accelerating to 12X or 16X.) We didn't have a 1X drive around so we calculated these numbers using theoretical transfer rates, which presents the best-case analysis.

To isolate recording performance, recall that we rendered in DVD-compatible MPEG-2, so rendering and writing time was very minimal (menus only) for the first burn, and non-existent for subsequent writes. Rendering times would boost dramatically, at least for the first burn, if we encoded within Encore. The results are shown in Table 5.

If you're still running a 1X DVD drive, the cost per hour saved on one project is a ridiculously cheap $26.47, or $.88 each for 30 projects. Savings are less dramatic when upgrading from a 2.4X drive, which costs $3.06 per hour saved after 30 projects.

Of course, as the last stage before delivery (unless you're printing your DVDs as well), shaving five or ten minutes off the process feels like a lot, especially when you're burning your last discs as the customer is knocking on your door (been there, done that). This factor alone may make periodically upgrading to the fastest available burner a sound decision.

Overall, our recommendations vary by your situation. If you're looking for a cheap reduction of post-production time via system performance, the simplest decision is to upgrade to the fastest available burner. If you're buying a new computer system, opt for the fastest available processor over a dual-processor system. As for RAM, going beyond 1GB probably doesn't make costs/time-savings sense, and neither do Ultra-SCSI 320 disks.

If you're in an extremely time-critical production environment, or could benefit from some measure of media redundancy, DDRs are an attractive, though pricey option. Current prices bear a substantial early-adopter premium, but as prices drop—as they inevitably will—this product category will become increasingly alluring.