LJ Archive



Issue #87, July 2001

Readers sound off.

MPEG Unpegged

I've been deeply involved with MPEG for several months now, so your article on MPEG-1 playback programs caught my eye (LJ May 2001). I found several factual errors about MPEG in the article.

First, MPEG-2 video does not necessarily have better video quality than MPEG-1: the differences between the video portions of the MPEG-1 and MPEG-2 standards are fairly minor. An MPEG-1 file with a 720 x 480 frame size, compressed to 6 Mbit/s is legal, and will be very similar in appearance to a 720 x 480 6 Mbit/s MPEG-2 movie.

Second, the author states that “not all MPEG-1 files are entirely `compliant”'. The MPEG standards define what a compliant decoder is expected to be able to handle, but not how a compliant encoder works. In other words, a compliant decoder is not one that is “tolerant”, but is instead one that adheres closely to the letter of the ISO 13818 standard, so as not to be surprised by the output of a novel (but legal!) encoder. Unfortunately for free software authors, these documents are expensive: the basic set of MPEG-2 PDFs (ISO 13818-1 through -3) costs $424, and the complete set is $1,390 (from http://webstore.ansi.org/). It's little wonder that commercial MPEG products far outstrip free ones' capabilities, in nearly all cases.

Third, the author states that an “MPEG-1 audio stream...is an MP3 file”. This is not always true, and is not even likely. MPEG-1 defines three different audio encodings (or “layers”). Layer I audio is the most basic, but it isn't used very often. Layer II is the most common: video CDs and MPEG files you download from the Internet almost always use Layer II audio. Layer III (aka MP3) is optional, so most MPEG decoders don't include support for it. Since few decoders support Layer III audio, most encoder creators also don't bother including support for it.

—Warren Young

Certified Sword

Just a note to let you know that the certified sword cuts both directions (Editorial focus, LJ May 2001). As CIO of a multimillion dollar corporation it is my job to not only run the IS department but to hire and fire employees. One of the first questions I ask is if the prospective employee has any certifications, if so I politely tell them “I'll let you know if we can use you” and promptly throw their application into the garbage can.

Before you ask, no I am not certified. I have however taught pre-MCSE classes at Unisoft Institute of Technology in Houston and was horrified to learn that I had to teach the way the test worked, and the way the real world worked (pre-MCSE in this case really meant A+ and Networking certification). This effectively meant that I held two classes in one, which to say the least was difficult. Additionally, long ago before computers were my profession I was an ASE-certified mechanic. Since I have passed 10 ASE certifications I can tell you that they are just as much a joke as computer certifications. I quickly realized that even holding all the certifications I did, and after graduating from a top automotive technical school with a 4.0 GPA and Alpha Beta Kappa National Honor Society, that I was not a very good mechanic.

To me, being certified means that the person does not have enough knowledge or experience to get the job on their own merits and hopes that this piece of paper will help them, and it does not. In my experience the only time certifications help you is when you are applying to a business where the person responsible for creating hiring policies is not a real computer technician.

I am forced to deal with MIS and IS degrees from recent college graduates as well as a plethora of certifications on a regular basis. Unfortunately, I have found that the people who have neither a degree nor a certification but who have been working with computers for ten years are much better equipped to handle the job. At least if they are inexperienced I can teach them the way things really work instead of attempting to retrain them after they have their degree or certification.

—Allan Hall

Carried Away with Gratitude

I very much enjoyed the April 2001 Linux Journal article “Linux on Carrier Grade Web Servers”. You did a nice job of describing the software choice, hardware environment and test results. I look forward to future articles discussing the other LVS implementations (direct routing and IP tunneling) and comparing their stability and performance with that of the NAT implementation.

Thank you.

—Bill Landahl

Some Saucy Suggestions

I enjoyed your articles on Linux Certification (LJ May 2001). I thought the “real-life” experience was very telling, although perhaps toned-down a bit to protect the vendors.

Here's my thoughts on what I read:

We can earn an extra $10K per year by becoming certified? Really? Who can? New grads? Having worked on, supported and/or maintained SVR4, AIX, HP-UX and Solaris for twenty years, I can't imagine getting another $10K just because I had some Linux certificate.

I looked at some of the questions from Red Hat's and Sair's study guides and tests. What a crock! “What's the fdisk type code for a Linux swap partition?” Who cares?! Look it up by typing l to list the types. Forgot that command? Type ? to list them all. Better yet were the impossible to understand questions and answers on Sair's test. Their “correct” answer for wc -l * is that it returns the total number of lines in the files. Gee, my experience is that it shows the line count for each file, followed by the total, but that answer isn't available. Yes, they want the entire Linux community to help improve the tests, but if they can't get the simple things right, I'd hate to see how they do with the hard topics.

Finally, the exam companies could learn a good lesson from the FCC and ARRL. The amateur radio exams are also multiple choice, but they are composed of a certain number of sub-elements. Each sub-element has a number or required topics. Each topic has a number of published questions and answers, with references to the rules and regulations. The effect is, the actual exam might have only 25 questions, but those questions are pulled from a pool of several hundred, and each critical element is covered.

—Mike Hall

Thanks for the GRUB

Mr. Marshall,

I want to extend a gigantic thank you for the article in the May 2001 issue of Linux Journal on the GNU Boot loader, “Boot with GRUB”. It could not have arrived at a better time.

We have a Linux machine whose main (boot) hard-drive started giving us IDE bus resets and other attendant errors. It became unusable although we are pretty sure the files we need are probably still good.

I tried constructing a new system from scratch and then copying the needed files and applications to the new system. Unfortunately this didn't work.

After some effort I was able to clone the bad drive onto a similarly-sized replacement drive using Norton's Ghost program. However, the LILO booter was no longer functional.

With the use of the information in your article I was able to construct a boot floppy that would get the replacement drive booted, and then I ran LILO on it to get the boot configuration properly re-written onto the drive. It is now a booting system.

—Keith Ericson

What Do You Expect?

In the “Best of Technical Support” May 2001 a suggestion was made to use the command expect. The editor inserted a note that expect was described in an article published in the December 2000 Linux Journal but did not mention the specific article, author or page number. I relied on the Interactive Journal to find it. However, expect did not get picked up by your search engine. I ended up searching each article with my web browser's find feature and did locate the article: “Linux System Administration: A User's Guide” by Marcel Gagné. May I suggest that when referencing an earlier article that you use a fuller citation. Thanks.

—George Palma

In addition to Marcel's article, we've run two other articles on expect. One can be found in issue 54, “Automating Tasks with expect” and one in 68, “What Can You Expect?”


History Lesson

I would be more inclined to take Tobin Maginnis' infomercial on Sair Certification, “Why be Certified”, seriously, if his grasp of PC history wasn't as shaky as his understanding of Shakespeare (LJ May 2001).

When IBM introduced the original PC, it didn't “revolutionize the technology”. The design borrowed pretty heavily from the Apple II, and for the first few years of its life, it was a fairly pathetic machine. However, it had the one magic component, those three letters on the label. That made it socially acceptable in the office, even though it was distinctly inferior to the CP/M machines of the time. (On the positive side, it brought an end to the bewildering proliferation of floppy disk formats then current.)

Ever since Novell hit on the concept of certification as an extra cash cow, and corrupted the term “engineer” in the process, it's been making life easier for ignorant personnel (aka HR) types to sort resumes into piles, and I don't suppose that's going to go away. The only question is, to which pile will this certificate direct my resume?

—Alan Rocker

Deep Pockets

I received the latest issue with the Training & Certification focus and was very disappointed to read that Red Hat's RHCE program was given essentially no print space, despite being widely recognized as the industry leader in Linux certification.

Having just completed the course, I can say that it is an accurate measure of a person's basic Linux systems administration skills, and even with 6+ years experience administering Linux, I found the class informative and the exam challenging.

I find the lack of mention of the course very disturbing, and I can only hope that this is not the beginning of a trend that will see LJ catering towards advertisers with deep pockets rather than accurately reporting on the Linux world.

—Cheyenne T. Greatorex, RHCE

Cheyenne, There certainly is no such trend. Between Sair, LCI and Red Hat I would have to say that the latter has the deepest pockets.


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