In-house CD-ROM recording - the newest hardware developments; here's the latest about price, speed, formats, buffer size, and more.
It was about a year ago that I last discussed in-house CD-ROM recording in detail, and since then things have changed dramatically for the better. At that time, in-house CD-ROM recording was still somewhat esoteric, primarily targeted to those who develop textual databases and multimedia titles. Some of the recording was still voodoo practice, and it required devotion, endurance, and about $3,000 for the hardware and the software.
Today, the most typical hardware and software CD recorder bundles range between $850 and $1,800. The unit from Pioneer stands out from the crowd, not so much by its unique capabilities but by its unusually high price tag of about $3,500. At the same time, you could find the single-speed RCD 202 from Pinnacle for $399 just last month.
The installation of the hardware can be quite easy. Most important, the emphasis is shifting from using it for authoring CD-ROM databases to the mainstream application of copying files to the CD for backup or small-scale distribution purposes. This year, I'm not carrying piles of transparencies for my four workshops at the National Online Meeting with me but instead I'm recording them to a CD. The recording itself is still more complex than making a backup to a streamed tape drive, but it is far more efficient--depending on the hardware and software combination that you choose. Both the latest hardware and the latest software developments support this mainstreaming of no-frills CD-ROM recording that would satisfy most of us most of the time.
There are about 20 hardware and software combinations to choose from, but the actual number of models is less than that, as many of the offerings are merely repackaged and/or relabeled and slightly customized versions of the brand-name products from Yamaha, Sony, Philips, JVC, Pioneer, and Ricoh.
I'll discuss the most important selection criteria for the hardware now, and then I'll focus on the premastering software in next month's CD-ROM Commentaries column. I should emphasize here that bundling options (and prices) keep changing, so it is more important to understand what the most relevant factors are than to go for a given brand and model. Ricoh, for example, had the lowest price for a double-speed read/write drive with a 512 KB buffer earlier this year, and in March it sweetened the deal by selling a quadruple-speed drive with a buffer that is expandable up to 8 MB for the same price.
Strange as it may seem, it sometimes happens that the hardware vendor bundles its product with premastering software that does not bring the best out in its hardware. This is the case with Express Writer from Micro Design International. While the drive supports Red Book (i.e., CD) Audio, the software does not. Similarly, while most drives would be capable of recording in Kodak Photo CD format, the bundled software does not offer this functionality.
Speed--Not So Fast
Typically, the first thing you learn about a CD-recorder is whether it is a 1x, 2x, or 4x drive, i.e., one capable of recording at 150, 300, or 600 KB/second. When I was a kid, speed was the first thing I learned about a car. Today, I care more about things like comfort, safety, handling, and gas mileage. The same applies to CD recorders. Quadruple-speed recording sounds good, but it often does not work because your system can't cope with the demands of uninterrupted transfer of data from the hard disk to the CD-ROM at that rate.
CD recording is like CPR: once you've started, you have to continue at the same pace. No wonder paramedics take turns doing CPR, switching places every few minutes. The hard disk, however, has no buddy, so when it pauses for thermal calibration (the equivalent of wiping the sweat off your brow), the dreaded buffer-underrun situation emerges and the disc is ruined.
I very often choose a slower mode (2x or even 1x) for safe recording. This, however, may not be possible if the drive isn't capable of switching to lower gear. For example, Pioneer's quadruple-speed drive can be set to 2x but not to 1x, though in a case where thousands of small files are to be recorded, this may be necessary.
The best premastering software programs make a test run at the higher speed and warn you if your hard disk will not be able to cope. Recording speed may be important when you press a new disc every other day in a dozen copies. For a typical user, however, it does not really matter whether backing up a 250 MB file set takes eight or 16 minutes once a week. Reliability spares you the "Maalox moment" and saves you much more time.
The other aspect of speed is that of reading. Don't even think about using a CD reader as a regular CD-ROM recorder. It is OK for testing the functional and format integrity of the just-recorded disc, but it is not appropriate for running applications. CD-R drives, even the ones with 4x transfer rates, tend to have poor response time when acting like CD-ROM readers. The reason for this is that the read/write heads are much heavier than those used in the CD-ROM drives; therefore, the seek time to get to the desired track can be excruciatingly long (500-600 milliseconds or more). This has much more bearing on the response time--especially for text databases--than transfer rate.
CD-ROMs come in a rainbow of formats: Red Book, Yellow Book, Green Book, Blue Book, White Book, and Orange Book. These refer to the binder color on the original documentation. Alternatively (just to muddy the water), other format names abound: CD-DA, CD-ROM, CD-ROM XA, CD-i, CD Plus, Video CD, Photo CD, Multisession.
Most of the current-generation recorders are capable of recording files in the standard CD-DA (digital audio), CD-ROM data (both IBM and Mac file formats), and CD-ROM XA (interleaved audio and video) formats if the premastering software provides the support. The CD Plus and Video CD formats are not yet widely featured by all recorders, and even less supported by software. But most IT readers probably will not lose sleep over this, nor will they miss the capability to create a CD-i disc. Multisession capability, however, is of prime importance. It allows the user to record a set of files, then to add another set--up to a limit.
While the formal limit is 99 sessions per disc, bear in mind that each session adds a considerable overhead of about 15 MB, so in the absurd extreme you may fill the capacity of a CD-ROM by recording about 40 sessions of 1-byte files. In normal situations, the capability of recording a couple of sessions to back up files at their different stages makes CD-ROM recording convenient and efficient, and multisession capability a must.
As we shall see later, there are now better techniques to write on CD-ROM. But first let's look at a critical factor in preventing the production of shiny coasters for your coffee table instead of CD-ROMs.
The buffers on the CD recorders are meant to act as a reservoir, to ensure that whenever the drive requires data to write on the disc, data will be available. The larger the buffer, the more data can be put in reserve and the less likely you are to run into the dreaded buffer underrun. These days, the minimum buffer is 512 KB, but 1 MB is more common. Of the 1996 models, about 75 percent have a 1 MB buffer. My aging Philips CDD522 has 2 MB, and that may be one of the key factors that helps me avoid producing coasters even when burning over 12,000 mostly small files in one session. It says a lot that the predecessor of this recorder, the CDD521, had only a 256 KB buffer and was marred by buffer underrun problems.
Even if your drive has a relatively small buffer, you can help avoid letting the buffer run dry by defragmenting your hard disk (which is as smart, anyhow, as washing your hands, and not only before recording or dining). Defragmenting your files is essential when your premastering software does not create a real image of the CD on the hard disk (or you don't have the space for it) but only a virtual image that merely points to the location of the files that are to be part of the recording session. It also helps if you have a hard drive with a transfer rate at least twice as fast as your recording speed. For nonchalant users who do need this advice, what I discuss below will come as good news, just as anticavity toothpaste is good news for those who brush less often than the dentist recommends.
The Right Way to Write a CD
In the beginning, you had to write a disc at once (DAO), and that was it. This meant pulling together as many files as you could to best take advantage of the single opportunity to write to a disc. Later, the multisession capability alleviated this problem by allowing you to add new files to the existing disc in subsequent sessions. Although separate sessions waste a lot of space, owing to each session's "overhead," it was a reasonable solution.
Then came the write-a-track-at-once (TAO) technology. The size of the track had to be at least 700 KB. The maximum size is the capacity of the disc. A total of 99 tracks can be written on a CD. Although there is also some overhead penalty with this technique (about 600 KB per track), it is not bad even by harddisk formatting standards. Even using the maximum number of tracks, you waste only 60 MB, as--if you wish--all the 99 tracks can be designated as a single session, and the session closing overhead is incurred only once.
More important, the TAO technique drastically reduces buffer underrun nightmares because a system failure (if the write operation cannot be finished) would ruin only a single track, not the entire disc.
Choosing a reasonable track size (say, 30 MB) to back up a group of files whose aggregate size is 270 MB is far less strenuous for your system--which has to maintain a constant transfer rate--than writing the entire 270 MB in one stretch. It is certainly easier to go 400 yards by swimming 16 lengths in your swimming pool (with the natural break at the turns) than it is to swim a straight 400-yard stretch in the ocean.
The latest craze is packet writing, which allows you to write variable-length packets of information with a mere 14 KB of overhead penalty per packet. Unfortunately, while there are many developers working on software support for packet writing (JVC, Sony, Incat, COREL), there is no agreement on a common standard yet.
Beyond the Drives
When you are comparing features and prices of drives, don't forget to check what is included. Many vendors don't include a controller card, cable, and/or the terminator. While the former sets you back about $300, and the latter only $20-$25, it is very irritating, when you finally set up your recorder and are ready to go, to discover that you don't have the terminator needed to close the last device on a SCSI chain.
Practically all recorders use a SCSI adapter, and you may recall that seven devices can be hooked up to one SCSI controller. If you have already a SCSI drive, you may be tempted to attach the recorder to that.
Don't! Just as no thinking parents should let a single grandparent struggle with two or more grandchildren who vie for her/his exclusive attention, you shouldn't split your SCSI controller's attention between two devices being used simultaneously, especially with one being so sensitive to timing.
Be ready, however, to iron out conflicts between the direct memory address and interrupt number of two SCSI controllers. Also, make sure that your vendor knows whether you have ISA, MCA, or PCI bus architecture, as the controller cards vary (and make Macintosh users feel superior).
Beyond the hardware issues, the premastering software issues are as important. The software can make or break a recorder, as we shall see next month.
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|Date:||May 1, 1996|
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