There is no compression.

Of course there's compression. Unless your ears work at 16-bit 44.1kHz and not analogically. If they'd decided on a 48kHz sampling rate or 24-bit encodings, then the capacity of the disk would change significantly. And, like it or not, that's compression. Lossy compression at that, since you're losing a significant amount of data (16bits is a lot fewer than an infinite number of bits, and a 44.1kHz sample rate is, again, much less than continuousness).

And, like it or not, that's compression.

My response was to this post:

I heard it was somewhat based on how much data could be fit on the CD and at what type of compression.

I realize that from a semantic standpoint, you could argue that different sampling frequencies can be considered "compression", even though that word isn't used (as far as I know) to describe the different data rates resulting from different sampling frequencies.

So I'm assuming that you mean one of the factors they considered when deciding upon the CD format was the sampling frequency and the sampling resolution, because those would also affect the amount of sound you could fit on a disc. All right, I'll give you that.

But my response was based on the current definition of compression as being short for "data compression", and I just wanted to make the point that the data rate of an audio compact disc is fixed, and that there's no "type of compression" on an audio compact disk since it is raw, uncompressed, unencrypted wave sample data.

Since an exact copy of the original data would take an infinite amount of storage, any storage of that same data on a finite storage medium would, by definition, be compression. But whatever.

And that would be raw, uncompressed PCM data, BTW. Don't want anyone to confuse the audio storage format of PCM with the containment system known as WAV (which can contain other audio storage formats). (I realize you said ``wave'' and not ``WAV'', but just to make it perfectly clear....)

I believe they reduced the spacing and extended the spiral track out further. I read somewhere recently that they could do this because of better reader hardware and the process for making CDs had improved enough to make the metal deposition quite uniform all the way to the edges. Now, as to where I read this I can't quite remember. Was in the last week or two though...

Don't you just hate it when that happens?

- Trevor

If you account for the hole in the middle of the CD, would that make the numbers work out exactly?

Naaah... makes it further off. You end up with .9902 in^3.



tanstaafl.

Perhaps the rounded edges of the CD make up that last fraction...

That is one bit of trivia I will have to remember. Perhaps I will even use it someday, under a somewhat bizarre set of circumstances...

I'm going to see if I can find the info on this.

Using "Tosho Doi" in some keyword searches, I found a few items including this (interesting in other respects) article from Stereophile . It's not 100% consistent with Doi's interview answer, but it doesn't contradict it, either -- I could see the Von Karajan theory fitting with the other Sony explanation if, as cited in the footnote, HVK was buddies with a bigwig at Sony.

Here's another spin, but with the only reference being the previously mentioned interview.

Based on the Doi interview and the Stereophile piece, I'm taking it out of my list of ULs.

(edit: Oh, and an interesting digital aside on HVK in some liner notes here .)

Perhaps the rounded edges of the CD make up that last fraction...

Oh, crap. That's just an *invitation* for Doug to factor in the volume lost outside a half-circle edge of 1.5mm diameter!

If the radius is irregular, we're doomed.

Ok, here is another one that I have wondered about for a while:

Why do most prices end with .99 or .95? Where did the odd pricing start and why? I know that people will say that things are priced that way because consumers will buy things thinking that $14.99 is less money than $15.00, but I think that I've heard that the odd pricing thing started with another intent. And whats with the 9/10th of a cent tagged on to gasoline prices? That's another one that pisses me off.

Edit:

here is one little bit of explaination that I found. It reads:

Odd-Even Pricing


Many products today are sold at prices with "odd" endings--that is, rather than selling something that $10.00, it is sold at $9.99. Interestingly, the practice was started not so much to deceive consumers, but rather to make sure that dishonest clerks would have to "ring up" a purchase in order to give change. One theory today is that consumers will conceive the $9.99 price as "nine dollars plus 'change'" rather than the effective $10.

Recent research has shown that odd price endings appear to have some modest effects under some circumstances--that is, consumers seem to be influenced a little bit, but not greatly. Interestingly, such effects could not be replicated in Germany, perhaps because of cultural differences.

Odd endings may have significant implications for the positioning of goods. Discount stores tend to use these endings, while upscale department stores often use whole dollar amounts as a sign of quality. While inflation has undoubtedly changed the figures involved, reseach done in the 1980s suggested odd prices were more effective below $7.00, where people often wanted to feel they got a bargain, while diners who paid more than that amount seemed to prefer the assurance of quality implied by a whole figure.

At Circuit City, they use different numbers of cents to indicate sale conditions. For example, 99 cents might mean normal price, 98 cents might mean clearance, 97 might mean open-box, and 95 might mean sale price. I forget what correlates to what, but it's something like that. Other stores might also use similar systems. On the other hand, I'm sure that that's not the reason it was started, but just abuse of a system that had already been established.

Oh, and if I remember correctly, the nine tenths of a cent on gas prices is part of the gas tax. That is, the gas tax specifies something and nine tenths of a cent per gallon, and the retailers just got used to passing that cost on directly, or some such. (Seems like it would be easier to just overcharge the consumer by one tenth of a cent, but what do I know?)

BTW, I agree with what wfaulk said. I mentioned compression because the sound recorded on current audio CDs is not the actual sound recorded. It's compressed, I believe by chopping out some high and low frequencies (similar to MP3, but significantly less). This is the reason we have the DVD Audio and Super Audio CD formats. They want to fill in all that missing data that had to be cut in order to fit on a regular CD by allowing more data to be fit on these new mediums.

Ok, I think I meant what wfaulk was talking about regarding sampling rates, and not the chopping...

Here's one of the articles I was thinking of, talking about DVD Audio and Super Audio CDs.

http://www.audiorevolution.com/equip/dvdavssacd/index.html

You guys are such square thinkers. The outside of the box converse to what you said.

You can store an infinite amount of data using 1 bit of storage.

How?

If you have a infinite amount of data, in a sequence that looks like this:

989563482947562821837372... and so on, you can place one decimal point thus:

9.89563482947562821837372... and then get a scaled storage medium that is marked from 0 to 10 and place 1 mark just below the "10" mark near the 9.8th position. That 1 bit of data represents an infinite amount of information.

And also, you don't need an infinite amount of description to describe the exact copy of the music. It would be finite. Large yes, but finite.

Calvin

Hey speaking of CD's... how goes my sun tanned CD's? ;-D

Calvin

how goes my sun tanned CD's? ;-D

I have officially admitted defeat.

Cleaning the damage caused by the suntan lotion was trivial. However, the CDs were in such bad condition otherwise with deep scratches running radially, and irregular blemishes a quarter inch across that I could not get them to play error free. I was able to get them to where I could rip and encode all the tracks, but some of the tracks still have artifacts and skips.

Oddly, the CDs appear playable now -- I have CDs that look worse that play with no problems. But I cannot make them work perfectly.

tanstaafl.

I hope you're joking on both of those points.

In reply to:

---

Just saying that a factor of P is P and 1 isn't quite what they had in mind. Finding the values of the two prime numbers that make up P is much harder as you know

---

Well unless the two (prime) numbers that were multiplied to make P were 1 and P, then the resulting number from this multiplication can *never* be prime.

However what you are saying is that the difficulty of finding quickly large prime (or near-prime) numbers is a major cornerstone of modern cryptographic systems.

So, once a quick way is found to find (also called factoring) such large numbers then this cornerstone is severely weakened.

Its this aspect that Gates (and others) have previously commented on.

I've been out of town all week, so I come to this sobject a little later than most but heres some comments:

In reply to:

---

Another little story is how US NTSC (Never The Same Color ) television uses 60 fields (or 30 frames) per second. This was becuase of the US's power system being 120volts AC. The power basically became the timeing device. Someone determined that all humans really need is 45 fields per second to similate a moving image, so the 60 is really over kill and a waste of information. Needing to put out 30 frames per second, NTSC had to sacrifice scan lines per frame. In contrast, PAL uses fewer frames per second (but still enough) but allow for more scan lines. Because of this, PAL has always been considered to be better than NTSC. So it is interesting that the first TV makers in the US were not limited by their own means, but by Edison for picking the number 120. It would be interesting to go back and find out "why 120?"

---

PAL is considered superior to NTSC, not just because they lowered the scan rate to 50 fields/second and therefore increased the number of scan lines per field - they did this trade-off to keep the effective 'horizontal' scan rate for both NTSC and PAL the same. Hence a PAL TV set can often receive and display a black and white NTSC signal without problems.

PAL came second (NTSC was the first all-electronic TV scanning system).

Because PAL came second they had the chance to fix some of the defects with NTSC, one major one being the annoying 'loss of colour' signal phase lock, causing the whole screen field to change colour (you know those faces that flash green and back again).

They fixed this problem with PAL by making every other scan line in the field reverse/invert the colour phase signal, thus stopping those 'loss of colour' lock problems affecting all scan lines in the field (worst case it would affect 2 scan lines and the eye will blend such errors making them much less obvious).

This also gave rise to the name for PAL - it stands for something like Phase (alteration) on Alternate Lines (PAL).

the other comment about 60 fields/second, in fact NTSC runs at 59.997 fields/second or something close to stop any mains interference caused by 60Hz mains.

I can't recall why 60Hz is used, I believe Nikola Telsa (who designed the AC systems used in America today)
[Edison invented/pushed DC, Telsa invented just about everything to do with AC, single phase, 3 phase the works], picked 120 volts because it was considered much safer than any other voltage in use at the time [e.g. 200 Volts DC].

However, 60 is a multiple of lots of numbers and has a lot of factors and this fixation with 60 can be traced back to the Sumerians.
These are the guys who gave us 60 seconds a minute. 60 Minutes a hour and 360 degrees in a circle to name some things.

A bigger question is, why do the countries that have 220 Volts AC power use 50 Hertz as their mains voltage frequency and not 60?

I think that the 50/60 hertz relates to how fast the generator sets of the 19th century could be spun to make AC power, at 60 Hertz the set would need to spin at 3600 RPM, at 50 Hertz, 3000 RPM.

Regarding Railway gauges: not everywhere uses the 5 foot 10 or whatever gauge used in the US.

Here in New Zealand we use 3 foot 6 inch as our railway gauge - the reason mainly being that because this is such a rocky/mountainous/geologically active country using a smaller railway gauge meant that the diameter of the tunnels/ width of bridges/embankments/viaducts etc that had to be built could be "smaller" and thus cheaper to build.
So, because of this decision made about 140 years ago we now have a railway system which trains cannot go much above 60 mph without the trains rocking too much.
Hence Railway is not a popular freight or public transport mechanism.
Good call guys.


On a related note, the current QWERTY layout on the keyboard was (carefully) designed to prevent the typists (who used the early typewriter models) from being able to type most of the commonly adjacent letters simultaneously which could cause the keys to jam together in the first typewriters made.
[A problem which was overcome fairly quickly, but by then the QWERTY layout had become common practise].

So the QWERTY layout is in use today to overcome a mechanical design defect of the earliest mechanical typewriters designed to SLOW typists of the day down.
It has been proven that in some cases as straight alphabetical keyboard can be faster to type on than a QWERTY keyboard, but the QWERTY layout is now firmly entrenched.

Actually, QWERTY was designed to speed typists up, not slow them down. The idea was that the developer of the QWERTY keyboard (I forget his name right now) placed the keys in that order in order to prevent the striking levers from locking together. (If you have an old manual typewriter lying around, you can duplicate this locking.) Before he developed the QWERTY keyboard, typists had to type slowly in order to keep keys from locking together. But by rearranging the keys, he kept the common diads from being placed close together in the striking levers. Since the typists then didn't have to worry about the levers sticking together anymore, they were free to type as fast as they wanted with fewer repercussions.

Oh -- and if you can show me a good study that shows that any particular keyboard is faster than QWERTY, I'd like to see it. (Not to imply that QWERTY is better, but, rather, that none is better than another, at least for just the letters.)

(I know I rambled a little bit there, but I haven't had as much sleep as I'd like.)

Greetings!

I remember hearing that it also involved distributing the most common letters evenly across all of the fingers. This way, you can build better speed. Or so the story went.

Well, there may have been some thought to generally placing the elements of common diads on the opposite sides of the keyboard (that would be one good way to keep the striking levers far apart), but you might be thinking of the Dvorak keyboard. In that arrangement, all of the common English vowels are in the home row under the left hand, and the most common consonants are on the home row under the right hand. Since English words tend to a more-or-less consonant-vowel-consonant rhythm that would tend to make a left-right-left rhythm when typing.

(BTW, the only well-known studies that show that Dvorak's keyboard layout are superior are the ones conducted by Dvorak himself, and he had a financial stake in a venture promoting his keyboards.)

And before someone asks, in this case "Dvorak" refers to the man who invented that keyboard, NOT the computer columnist who writes for PC Magazine and hosts "Silicon Spin" on ZDTV. Different people. If they're related, it's only distantly.

It used to be 60hz until they added colour to the signal and then it became 59.94hz. No idea why it is exactly that though

- Trevor

At Circuit City, they use different numbers of cents to indicate sale conditions

Best Buy does this as well, and I think 94 means it's on closeout. It's kinda nice to know, because you can see exactly what items they are planning on getting rid of shortly. Having several friends work there has revealed a lot I ddn't need to know about retail stores.

I'm convinced the sun screen lotion did in the CD, not the scratches. The scratches were in place before the CD were sun screened, and there was no skipping or errors of any sort until the sun screen got on the CD. ;-)

I don't even recall the brand of sunscreen, think it was most likely Coppertone SPF 40. I think an experiment is in order -- spread Coppertone SPF 40 on a clean CD-R (the effect is the same on CD-R's) and see if it can be reversed. :-D

Doug you can keep the CD's. Thanks for trying :-)

Calvin

Having several friends work there has revealed a lot I ddn't need to know about retail stores.

For a while, a friend was an assistant manager at a bicycle shop here (one of the largest). Their price tags were square fluorescent green stickers (orange for closeout). If you saw a price on something of $99.95, you would also see a number/code up above offset to the right, something like 0005. That was simply the employee discount price (on which they could still make a little money) printed with no decimals in reverse. And, yes, figures of $99.95 - 0005 were typical. 100%+ markup.

Straying a bit off topic, but I worked at a bike shop for several years. We made almost NO money on bikes (we had pretty low prices, but not super low). But we made a killing on accessories. That is why we would rather throw in a few $10 water bottles and some $12 water bottle holders rather than knock $44 off of the price of the bike. That "$44" that we just "threw in" only cost us maybe $8. On the otherhand, we made at most $50 off a bike. Service was another money maker.

OK, another WHY? question.
Why is a 2x4 not?
I know its because of milling etc etc, but why call it a 2x4 when it is NEVER that size.
You can't tell me that it starts out as 2x4 then trimmed down to be straight because the length is a huge factor for that.
Most other engineered lumber is the actual size, 3/4 ply is 3/4 thick.
3/4 MDF is 3/4 even though its pressed into that shape and starts out 3 feet thick, they don't call it 3foot MDF!
Same question for measuring nails in pennies. Has the penny been that size since it was first minted or am I missing something?
I don't think James Burke would cover that.
I did like him in Tomorrows World, yes I am old enough to remember him in that!

I'm guessing that the 2x4 thing is similar to how all soda is called "coke" in some areas and how all in-line skates are called "rollerblades" (I used to skate for them and they faught this as best they could!!) and how all cotton swabs are called "q-tips" etc.... Older homes DO have 2"x4" 2x4's. I am guessing that there was a gradual change to the new size and that carpenders still refered to them as 2x4's because they used them inplace of what the original 2"x4" versions were used for....

But that is pure guess.

On the otherhand, we made at most $50 off a bike.

Yes. When I mentioned markups, I probably should have qualified that. All those green tags were on the sexy lycra tights, Italian shoes, water bottles, etc. People will spend a lot of time price shopping the big stuff, but then get killed on the little bits. Also, I gather that 100% markup is pretty standard stuff for retail lines like clothing -- overall retailers can need those margins to cover the XXS and oddball items that don't move..