back to article Compact Disc: 25 years old today

The Compact Disc is 25 years old. Though the digital audio format's development stretches back many years before 17 August 1982, that was the date on which the world's first CD pressing plant punched out its very first disc. CD logo According to Philips - with Sony, the format's co-developer - the first disc off the Hanover, …

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And not one mention...

Not one mention of the infamous Tomorrows World segment - where they were trying to bestow the virtues of it not scratching like vinyl discs - when the disc was taken out the player, baked beans were eaten off of it, the disc was cleaned and popped back in the player - not a skip, jitter, or wobble from the player.

It's just like girls in pushup bras that is; false advertising, simple as that.

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CIRC

The article omits the really clever bit, namely the *Cross-interleaved" part of the error correction. What you effectively have is 2-dimensional parity checking, so that the error correction is very robust. In particular, it's robust against scratches.

Try an experiment:

Take an old (unwanted) CD, and either:

- scratch it severely with a sharp object

- draw 2mm thick radial lines on it in black marker.

It will still play perfectly.

[Confusingly, the *label* side is very vulnerable: it's very easy to destroy a CD with a screwdriver by attacking the labelled side, whereas the (apparently fragile) shiny side is almost impossible to destroy]

BTW, don't microwave CDs. Although the light-show is impressive, the smell of burnt plastic is *really* not nice!

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Some mistakes

Well the sample-rate is 44.1 kHz not 44.8 kHz.

And actually the first 8 to 14 encoding is there to prevent long runs of zeroes or ones which would mean a substancial problem with syncing.

Another thing to take into consideration is that the CD is not the first optical consumer disk format to become popular. The LaserDisk is in fact even older than the CD.

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Title

Richard Neill "Try an experiment: Take an old (unwanted) CD, and either: - scratch it severely with a sharp object - draw 2mm thick radial lines on it in black marker."

Actually I did something like this after I got CD player, and discvered that the direction of the scratches and markings matters a great deal! As long as you vandalize only _radially_, the disk can take amazing amounts of damage before playback is affacted audibly, but just a single long scratch with a screwdriver drawn along the tracks can make it skip. This is a significant limitation in the error correction, as a broken player, or one with foreign objects stuffed in it, would probably make circular scratches to the spinning disk.

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Tom
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Still better than MP3

Regardless of the downloads on iTunes, the CD format (44.1 kHz and 16 bits/channel) is FAR superior to the silly (lossy) compressed MP3 junk. The download services don't provide full fidelity (lossless) tracks, and probably never will. Everyone who accepts the @#$%^& that MP3's pass for gets what they deserve. Stick with the original (and still the best) THE CD!

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Anonymous Coward

Ahh nostalgia

Is it really that long since I picked up my first CD player (A Philips CD101) ? I remember the claims about the durability of the the CDs and my mum tested it by knocking a CD out of the open window in my bedroom which skated down a pitched roof, dropped onto a concrete patio, bounced across it and landed in the flower bed. Dusted it off and it played perfectly.

I've still got the CD101 - I don't use it any more but its still fully functional.. who knows, in time, it might be worth something

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Anonymous Coward

MP3

@Tom:

Yes, CD is superior to MP3, but a good proportion of music buyers (and downloaders...) don't care. As a firend has suggested: convenience over quality.

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RE: Still better than MP3

I agree Tom, MP3 is a hideous format to have to listen to -- making well produced and mastered music sound like compressed, detail-free, rubbish.

I will only start buying music from download stores if they begin using something that doesn't throw half the music out -- FLAC would be nice, for instance.

Before any Vinyl-loving people comment, I am aware of the religious wars, at least CD music is produced and mastered to the format -- whereas MP3 is just CD with all the information removed.

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Anonymous Coward

Counterintuitive

The way the discs go into the player is a bit counterintuitive after using records. Everything is upsidedown including the stylus.

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Re: CIRC

How did the article fail to mention CIRC?

"CD encoding also employs Cross-Interleaved Reed-Solomon Coding (CIRC), which adds an extra, parity byte for every three bytes of data. The upshot: the player's electronics can easily and efficiently 'guess' what data masked by errors should have been, eliminating clicks and pops."

read "masked by errors" as "masked by scratches" and you're there.

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Loss of quality compared to LPs

What no-one seems to remember is that you lose the lower and higher end of the audio spectrum with a CD. Yes, you don't get the hiss and scratch, but when you compare a good quality LP to a CD, you'll notice the depth of sound is much better with the LP.

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pre-emphasis bit

I remember some early CDs (mostly ones pressed in Japan) made use of something called a "pre-emphasis bit" including my first copy of Electric Light Orchestra's Discovery.

The first CDs in our household were Pink Floyd's Dark Side Of The Moon, The Eagles' Greatest Hits and Dire Straits' Communique. The first CDs I bought though were Queen's Greatest Hits (though not the UK hits compilation) and Freddie's solo album Mr Bad Guy in 1985. Though until the early 1990s I was still buying most albums on vinyl.

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I want a laser turntable?

What ever became of the laser turntable shown on Tomorrows World that read LP's with a CD player style laser?

I still want one!!

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analog

as far as music is concerned, analog will always give a deeper, richer sound. IMHO

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No FLAC downloads?

You're not looking hard enough - I often buy FLAC downloads from Boomkat and Bleep.com. Some independent labels are more enlightened than the majors. Much better music as well, in my opinion...

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@Tom and Cameron

There is actually a FLAC quality download service on th net.

Linn Records (from Linn the Hi-FI guys) offers ultra high quality downloads for only a little more than the price of the MP3s.

http://www.linnrecords.com/linn-downloads.aspx

Chris

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LPs

Yes, LPs sound better than CDs. If you are under 25, have a £2000+ system, and only play them twice. After that, the effect of dragging a diamond through a small plastic channel takes its toll. To say nothing of the effects of small children or moving house.

LP's are crap and I'm very glad they are a thing of the past.

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Laser turntable ?

Come on, Googles not that hard to use

http://www.laser-turntable.com/

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Anonymous Coward

Laser turntable

They are still made and sold in japan, but I would prefer the ccd scanner based version, where a high quality ccd based digital microscope scans the surface. A system like that can read any optical format, including damaged lps, cds and dvds. If used with a high resolution ccd and a correct light source, it can even read blueray and hddvd discs.

"What no-one seems to remember is that you lose the lower and higher end of the audio spectrum with a CD."

You can't loose the lower end, just most of the players don't have the right quality amplifiers. Try using a digital player with digital output (uncompressed spif will do it). The highest frequency is 22050 Hz because of the digital format. Most lps can't store such high frequencies because of the graininess of the medium. What made old lps sound better was the better quality analog amplfiers, that sound more naturally for humans. Actually nothing stops someone from connecting a digital cd unit with a high precision nonlinear intrepolating digital to analog converter (not the cheap ones used in sony products) and send the output through a classic analog amp. You will be suprised...

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iTuneski

I think you will find do a very credible CD quality encoding.

Agree with Robert Long on LP's, only the ones I wouldn't like to admit I have sound any good. Because they have not been played !

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Vinyl religous wars

No you don't lose the top and bottom end of the audio spectrum with CDs compared to vinyl. Sampling theory (which is based on mathematical proofs) demonstrates that you need to samplee at least twice the highest frequency signal to be recreated. Hence CDs are sampled at 44.1Khz which is more than twice the 20Khz range of human hearing. Of course, if you are getting on a bit, (which means out of your teens) then the maximum frequency that you can hear will be steadily be reduced as the years go on.

Now none of this means that CD encoding is perfect - there are all sorts of engineering issues which means that you don't get the full theoretical reproduction. The limit in bit depth limits dynamic range.

However, for those that think that vinyl perfectly represents the analogue form of sound, then that's untrue. In the translation of sound waves to pressing wiggles in plastic there are many, many stages where distortions and inaccuracies are introduced. Vinyl itself has engineering limits on just how fine a detail can be represented, not to mention the ability of physical transducers to reproduce it. Vinyl has its limits on dynamic range as at the lower end it disappears into surface noise and at the top end then there are limits on the modulation that can be achieved. Adjacent grooves in the spiral also affect one another - on some heavily modulated sections you can often hear a shadow of the next revolution.

There's no denying that vinyl sounds different - it might well, to some ears at least, sound better. However, that's probably more to do with the the introduced distortions being subjectively more pleasant than that the essential technology allowing for better audio fidelity.

The other thing to note is that a lot of modern CDs just sound artificial because of the appalling tricks that are done in some recording studios - introducing so-called compression techniques to boost quieter sessions is one, but many are so often ret-tracked, re-sampled and generally messed about by producers that what comes out bears little resemblence to what went in.

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The perfection of vinyl debunked

I worked in audio in the days of vinyl and valve amps, and through the transition to transistor amps.

There are major problems with vinyl, some of which have already been listed above, but here are a few more:

1 the sound is cut with a lathe head on the master disc moving radially across the disc, but played back with an arm that describes an arc across the disc - this introduces distortion. (CDs use linear for recording and playback) I know linear playback decks exist, but not in my price range.

2 The disc spins with constant angular velocity (e.g. 78, 45, 33 rpm) so the outside moves faster (the linear velocity) under the pickup than the inside. This means early tracks have a higher frequency response than the inside ones. (CD uses constant linear velocity - CLV)

3 Conversely, the outside tracks are more prone to damage, but that is where all discs start, so there is always data there. (Cds play from inside out, so edge of disc is empty on standard 40- 60 minute albums)

4 Because it is an electro-mechanical system and subject to inertia, the lathe cuts low frequencies more easily than high frequencies. To compensate, the high frequencies are boosted (3dB per octave if memory serves) and the pre-amp has to attenuate by the same amount (RIAA equalisation) so low frequencies get boosted. this accentuates hum and turntable rumble, and is a non-linear processing of the signal, so subject to more distortion.

5 The moulding process introduces pops and clicks if the vinyl is not perfect, or if there are air bubbles or contamination. Vinyl pressing plants were not the clean rooms that CD plants are. We always used Deutsche Gramafon discs for testing as they were far superior to anything sold in Britain. Parlaphone discs (the Beatles, Pink Floyd) were EMI's middle range, so had a fair share of defects.

Vinyl discs could exhibit 20-30% total harmonic distortion (THD) when all these were added together, compared to 0.01% for CD.

So unless you have a £2,000 linear tracking deck and only play German classical records twice, then you are better off with CD.

As my hearing range has dropped an octave since I was a teenager (I now can't hear much above 10 kHz, compared to 20 kHz before) it is all fairly academic to me.

Sorry for the long post; just don't get me started on valve vs transistor amps!

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"Good Enough"

The problem is, that whilst CDs are definitely good, mp3s are 'good enough'.

I'm sure all the HiFI aficionados have been through this with their unenlightened friends; you try and show them how much better a CD is then an mp3, and even on your own beloved system you can barely register a nod out of them. On their own cheapy midi systems you'd be hard pushed to tell the difference yourself.

Unfortunately for us, nobody cares! As long as they can hear it well enough to make out the words they're happy.

So with the decline of CDs wonder what the future holds? Either the major distributors will start selling lossless digital files to us (at a premium, no doubt) or maybe HiFi manufacturers, desperate to save their industry, will do a deal with the record companies and start to distribute very high quality digital recordings to their customers - which will no doubt be at a *massive* increase in price...

'Linn Digibox' or the 'Medidian FLACbox' anyone....

*crys*

And - thanks for the theory and the recollections, GrahamT, interesting stuff!

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Vinyl

I'm 25 years old and am a keen Vinyl enthusiast, I've just purchased a new amp and speakers and I'm going to invest in a quality Turntable for my records.

When I have friends round at the weekend there is nothing better than warming the deck up and spinning some tunes. If I buy a CD I rip it straight to a high quality mp3. I am an mp3 junkie I have about 100gb and a media centre in my living room to use them.

I understand that the CD is the format of choice for quality and I still buy them because you get the album art and a proper feel of the work the artists put into the music. On the other hand though I can be found sifting through the stacks of records in our local second hand record shop.

I'm into rock music and there is a lot of collectable vinyl out there and a lot of bands put out special editions on picture disks. I recently done some conversion of Vinyl to mp3, some recordings turned out better than others. I was using a cheap deck with build in preamp I plan to do a better job when I get my new deck.

Anyway I'm waffling a bit. I think its great that we have a great choice between CD, Vinyl and Mp3's.

As you can see I'm passionate about music and I think ultimately its not about the format you use to play your music its the music itself that counts.

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Anonymous Coward

Album sleeves

Whilst i can agree you cant do much about the size of the old LP sleeves, CD has made the music experience at least visually less exciting, or is it me just being a kid in the 70's. But come on Led Zeppelins Houses of the Holy sleeve is a masterpiece, ok beatles fans St pepper

Whilst i work in IT i cant deal with buying a mp3 off the net it is not tangible. I like to feel i am getting something for my money.

It does appear to be a reflections of attitude, we are more on convenience, cheapness, than quality. For me thats a concern.

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CD vs MP3 vs Other

I listen to most of my music on the go - on a bus, in a noisy office or walking around. Even with expensive Sony noise-cancelling headphones picked up in Japan, it doesn't kill all external sounds. So of course, for me MP3 is more than good enough. I'm pretty sure most folks don't listen to music in an nicely isolated studio.

MP3 is also not very CPU intensive to decompress, so you can expect a good battery life on whatever device you are using. Look at how poorly "superior" formats like WMA perform, battery wise, to a device playing back MP3.

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Bless you...

Thanks to GrahamT and Steven Jones for the posting. I hate getting involved in vinyl/cd arguments - I'm usually the only person in the argument that understands sampling theory, but the added facts on vinyls faults were a great read.

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RE:CD vs MP3 vs Other

Personally, I moved from MP3 via WMA to ogg and thought it was the dog's bits. Then, for a laugh, I ripped some CDs to FLAC -- shortly afterwards I ripped the rest of my collection.

Unfortunately, I managed to break my FLAC-playing portable device -- so I'm now stuck with huge WAVs.

With a decent pair of earphones I can tell the difference, though they did cost almost as much as the player they're connected to.

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Anonymous Coward

Well SACD...

... is basically "LP-sound" without the issues. Also, due to being a niche-format, you tend to get much better mastering quality. Not that a well mastered CD would not sound stunning too, they are just harder to find. Also, with HDD-prices these days, anyone not using FLAC/ALAC by now is clearly missing out.

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Anonymous Coward

RE: I want a laser turntable?

Yes, they're rather cool pieces of kit. However I really want a cd player that looks/operates like a LP player. Basically a record player with a laser in the place of a stylus. Pointless, but fun!

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Please God, No

"What no-one seems to remember is that you lose the lower and higher end of the audio spectrum with a CD. Yes, you don't get the hiss and scratch, but when you compare a good quality LP to a CD, you'll notice the depth of sound is much better with the LP."

You're joking, I presume? CD doesn't give you rumble, wow&flutter, static clicks, ringing, harmonic distortion from tracking angle inaccuracies and warps, poor stereo separation, continuos hiss from surface dirt, jumping from fluff collected on the stylus or - BEST OF ALL - groove damage from PLAYING THE BLOODY THING IN THE FIRST PLACE.

Yeah, vinyl sounds better than CD, alright. Despite the fact that CD has better dynamic range, stereo separation, signal to noise ratio, distortion performance, playing time all in a nice, well defined 20hz-20khz range. I can't hear even any higher than 17khz, can you?

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Anonymous Coward

@GrahamT

Oh, please start on Valve vs Transistor amps! :D

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MP3 sound quality

People always seem to forget that colloquial MP3s usually describe CBR 128kbit/sec tracks, which have a lot of loss. But the encoder makes a huge difference -- 128kbit/sec encoded by LAME within the last year or two sounds just as good (according to double-blind listening tests, see Hydrogen Audio forums and wiki for info and links) as the "superior" formats like WMA and AAC at the same constant bit rate.

Using LAME's new VBR method, with the highest fidelity setting, you get tracks that are transparent (cannot be distinguished from the original source material; all FLACs for instance are transparent since they're lossless). In fact, tracks are transparent below that setting, but a bit of paranoia isn't a bad thing.

In order to save space (HDD may be cheap these days, but if you're like me and want backups of your music collection just in case...) I recently converted my FLAC collection into MP3s using LAME's absolute best VBR settings; the file sizes shrank significantly, and in all my side-by-side listening tests (which I ran before deleting the FLACs) I can't tell a lick of difference. Maybe if I had $4000 speakers connected to a $3000 amp coming via optical out of a $800 sound card, but I don't, and won't have that kind of money to spend on this...

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CD vs vinyl

The main thing you lose with a CD is not frequency response, it's resolution. 16 bits full-range doesn't give much scope for accuracy on the soft bits.

Re the frequency thing, actually you want more than 2 samples per cycle to get an accurate representation of the waveform, so CDs certainly won't give accurate representation up to 20kHz. But for those who didn't do their homework, Fourier says that creating a waveform at frequency X, your waveform will be made up of components at X, 2X, 3X, 4X, etc.. And since most people can't hear more than 20kHz, that inaccuracy isn't audible for anything above 10kHz. 4 samples per cycle at 10kHz still ain't perfect, but it's good enough that most people can't tell the difference. Note that I don't say "don't mind the difference" (which is the case with MP3) - most people actually wouldn't be able to tell them apart in a double-blind test.

More of a problem for poor low-end and high-end performance is the use of cheap shit parts in CD players. If your CD player's pre-amp is crap, your output will be crap. Less of an issue now that decent op-amps are cheap, but it was a major problem when CD players first came in. A friend opened his CD player up (second-hand one bought in the early 90s) and found a 741 (late-60s-era chip) in there - replacing it gave a serious improvement to the sound.

But by far the biggest problem is the audiophile community and fanbois in the magazines supporting it. "Yeah, my amp sounds better when I put it on speaker stands. Yeah, a £100 mains cables really improves the sound. Hey, look at these directional cables." I don't mind folks wasting their money, but as an electronic engineer I *do* mind them making baseless claims unsupported by evidence (or the laws of physics), especially when those claims are then taken as truth by people who don't have the engineering knowledge to realise they're talking crap.

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Jim

Quality of 'master'

The worrying thing for me is that with the loss of CDs then I lose my current 'master' quality copy. It's bad enough that production ethics have dropped so that source quality has dropped correspondingly but at least with a CD you have a pretty good archive copy that you can encode as the mood takes.

By the way, please stop quoting 20kHz as the top end of recovered signals from a CD. If you have a really good A/D converter with a truely awesome LPF you can achieve this but you are not gonna find this in consumer grade kit.

A 741 in a CD player, LOL. Those things were useless even in basic analogue circuit design by the end of the 80s, I would never dream of sticking one in an audio circuit!

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its all moot

Saying a song on CD is better than the same song in mp3 format is like saying a shit film's gonna be better in hi-def.

14 years old girls don't care - they just look at the makeup the singers wearing, older people don't care because their ears stopped working properly ever since thet went to that gig in the 70's (plus added natural loss due to decay).

Its the middle aged generation who've got nothing to do but surf the web and flick through cable/satellite channels when they get home from work who are vocal about these things.

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Never found out why...

From my very first CD, I always wondered: why didn't they include the album name, track listing or any other digital data in the original CD spec? Was it simply that nobody thought of it?

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re: I want a laser turntable?

i remember seeing this one when i was a kid. If i remember right, you had to play the record upside down.

I looked for one a few years ago in order to get an old record collection into digital format but was never able to find one...

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Vinyl is Crap!

... and CDs are for tossers! Nothing compares to a full 30-piece orchestra! The sound quality makes LPs and CD3 sound like a tin can and waxed sting setup.

Admittedly it's a little akward for the daily commute...

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Nostalgia

Well, now I'm feeling really old! I had one of those Philips CD100s (actually a Marantz but it was the same machine coloured gold). It cost £300 in 1984 having just come down from £600. It had limited controls and just a row of green leds to show which track was playing, but what an improvement on the total inconvenience and hassle of those horrible black scratchy vinyl things!

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J

DDD

Hey, thanks for reminding me of the DDD thing... Ages I hadn't seen that. I remember some albums in the early 90's having the tiny DDD printed on the back cover. Or ADD if analogically recorded, or even AAD -- although I don't recall seeing one of these AAD, since I guess they remixed the thing anyway, so it might be there were none...

Anyway, interesting memory lane stuff...

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"VHS styling"

I think the caption underneath the picture of the Philips CD-100 is wrong. It looks much more like a Philips Video 2000 player than any VHS machine. Which would make sense, because at the time Philips would have been marketing their VR2020 player. I had a VR2022 machine, which beat the pants off any VHS or Beta machine for quality (and tape run time), and the tapes looked cool too.

Also, I do like the sound of vinyl, but purely because it sounds "retro", rather than anything to do with fidelity or frequency ranges.

And on the subject of people who don't care about sound quality, this can be no more exemplified by chavs listening to music played off mobile phones in public. This crap really hurts my ears - but there really are people out there who really don't mind listen to MP3 music played through a *piezo buzzer* for a speaker!

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Re: Never found out why...

There are standards for the storage of track (and disc) meta data information and there have been for a long time.

The problem with this technology is that it required:

a) much more expensive decoding equipment to read, convert and display the data (compared to the comparitively cheap audio read circuitry)

b) the standard does not handle multiple languages / character sets. The recording industry is lazy - they'd rather have the same master but not have the track names than have to produce a different master for every language, and while the end CDs are cheap, the masters aren't (or weren't at any rate). In fact, the industry is so bad with this kind of data that they can't even manage to keep the disc ID (that is encoded) consistent or unique between CDs...

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Valves vs transistors

Well, to be quite frank, valve amps DO sound better than transistor amps, and for some very solid reasons.

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Anonymous Coward

Can't hear the difference?

I know a lot of the time you can't hear a difference, but a_lot_of_the_time != always .

Yes, that weird metallic bubbling/ringing sound, so familiar to home-rippers and P2P users, is extremely rare in commercial MP3s; but on more than one occassion I've heard professional recordings where the encoding has decided that the frequencies of the vocals are less important than the frequencies of the fuzz-boxed rhythm guitar, and the vocals drop out slightly on ever chord. Very distracting.

So these flaws exist. Can you avoid the flawed rips? No -- there is no real try-before-you-buy. If you want to listen to the track before you buy it, you're listening to a Real Audio, Windows Media or Flash stream with a different file encoding.

When I go into a CD shop, I can listen to exactly what I'm taking home.

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re: MP3 sound quality

I'm listening to an mp3 encoded with the current LAME VBR defaults (not even the paranoid, slow-down-encode-to-hell ones) on a 300 quid sound card attached to 100 quid Sennheisers, and I can't notice the difference either. Its averaging about 160kbps - rather a lot less than FLAC would take.

Probably because there isn't actually any that anyone can actually notice - unless you're the kind of person who can be convinced that a 400 quid HDMI lead is better than a 20 quid one....

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Silver badge

Bring back piano rolls!!!

As for laser-turntables, what a lovely idea, the laser doesn't scratch the disc, so the sound stays pure.

Except.

LP's are still static dust magnets, so you have to keep the surface very clean for the laser not to be interrupted...cleaned thoroughly by physical contact, which starts to degrade the surface...

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How many years...

... until the youf are asking what a seedy is?

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Square CDs

I've still got my copy of the only run of square CDs that Philips sanctioned way back in the Eighties for a charity auction.

I wonder if the CD is worth anything? :-))

IIRC only 40 were made. Mine is no. 2

Hey this is my pension we're talking about!

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