[trains are bad]

I have a basic grasp of how the audio CD works. It seems to work, but the absence of an embedded clock signal seems week to me, but apparently it works.

Anyway, my question is why?

Why not have some kind of audio file, PCM or otherwise, on the CD, which is read and played back by the playback device, like how my car CD player plays mp3s burned to a disk? Why attempt real-time playback at all?

Is it because technology was different back when it was created? Is it DRM motivated? Could it possibly be that the idea of embedding an audio waveform on a spinning disc, to be played back in real time, was too ingrained?

Of course when I buy CDs, I put them in my computer and use a special program to extract the audio to a usable format. Then if I want to play it in one of the gazillion CD players that somehow got popular, I have to use another special program to put it back to Redbook so that it can be susceptible to the individual transport and errors EVERY time it's played.

I just don't understand what the point is.

 

[F1GTR]

Quote:

Originally Posted by trains are bad Of course when I buy CDs, I put them in my computer and use a special program to extract the audio to a usable format. Then if I want to play it in one of the gazillion CD players that somehow got popular, I have to use another special program to put it back to Redbook so that it can be susceptible to the individual transport and errors EVERY time it's played. I just don't understand what the point is.

Call me old fashioned but I just don't understand what you're saying.

Why not just simply press the PLAY button and listen to the actual cd itself?

I find it extremely hard to believe that EVERY time you play a cd you encounter errors. If that's the case then you either don't own, or have never owned, a quality cd player. Somehow got popular? Perhaps convenience was the ticket.

 

[tkam]

http://en.wikipedia.org/wiki/Compact_disc

 

[trains are bad]

Quote:

Why not just simply press the PLAY button and listen to the actual cd itself?

Sure, but I'm speaking of the format. Why couldn't you do the same thing with a CD filled with WAV files? Why is there a special 'format for reconstructing an audio waveform from a spinning disc' which is useless for any other purpose?

Quote:

I find it extremely hard to believe that EVERY time you play a cd you encounter errors.

I said that every time you play the CD it's susceptible to errors. You have people saying that different colored CD-Rs sound differently and that expensive CD players sound better (though that's probably due more to the DAC). It just makes me wonder why we are 'reading music off discs' instead of just 'storing audio data files on discs'.

 

[tkam]

Quote:

Originally Posted by trains are bad I have a basic grasp of how the audio CD works. It seems to work, but the absence of an embedded clock signal seems week to me, but apparently it works. Why not have some kind of audio file, PCM or otherwise, on the CD, which is read and played back by the playback device, like how my car CD player plays mp3s burned to a disk? Why attempt real-time playback at all?

You really need to brush up your understandng of how audio cd's work. The redbook standard does infact specifiy 16-bit 44.1khz PCM...

http://en.wikipedia.org/wiki/Red_Boo...CD_standard%29

 

[trains are bad]

Sigh. I know how redbook CDs work. 16 bit word length, twos complement, eight to fourteen expansion, 44.1kHz yadda yadda like the beginning of the Shellac song.

Does anybody understand what I'm saying? That it seems less efficient to actually encode the audio on the CD (redbook) rather than just store an audio data file on the CD such as flac, mp3, or some uncompressed other format, to be decoded and played back in software? And that also eliminates any differences in the transport used?

 

[bigshot]

Quote:

Originally Posted by trains are bad Sure, but I'm speaking of the format. Why couldn't you do the same thing with a CD filled with WAV files? Why is there a special 'format for reconstructing an audio waveform from a spinning disc' which is useless for any other purpose?

A better question would be why there's WAV and AIFF.

See ya
Steve

 

[CookieFactory]

Quote:

Originally Posted by bigshot A better question would be why there's WAV and AIFF. See ya Steve

Tagging.

 

[F1GTR]

I don't keep up with the MP3 technology like I should but do they now have 1411.2 kbit/s MP3's? I've been under the impression that 320 is about as high as they go.

 

[Cyrilix]

Quote:

Originally Posted by F1GTR I don't keep up with the MP3 technology like I should but do they now have 1411.2 kbit/s MP3's? I've been under the impression that 320 is about as high as they go.

What would be the point? MP3s are about compression.

 

[F1GTR]

Quote:

Originally Posted by Cyrilix What would be the point? MP3s are about compression.

Well clearly that confirms me knowing very little about MP3 technology. I always just thought it was a method of listening to music without having to hassle with a CD, Record, Tape, etc.

As for the point, to me it's always about sound quality.

 

[Duggeh]

The CD was to replace the 33RPM Record.

They wanted somethign cheap to produce, something tougher and more resiliant to physical damage. Soemthing that was wear-proof. Something easier to use. Something with better sound quality, something more portable, something they could patent, and something that would be sucked up by the consumer.

In terms of the audio tech involved, the redbook spec allowed for what at the time, was superb high quality sound for even the big spending hi fi fan, the fact that DGG dropped the 33RPM Record altogether and purely published on CD was a testiment to that.

CDs as concerns the actual sound storage format? I think it makes snse given the tech of the time and the factors involved.

Where is my thoguht train going with this post? I've no idea, ill just stop now.

 

[HumanMedia]

I think the original question is just a younger persons perspective. Back when CD came out, computers could barely do word processing. Most could only emit a single beep tone and there were no personal computer sound formats, sound cards, or even enough space to store the simple waveform on them. CDs were an absolutely huge amount of data back then and a simple device to play them was a milestone in digital development. It was only years after they were born that any of these formats or technologies slowly emerged.

 

[Garbz]

So back to the original question. Answer it like this. What came first, the random data read off a CD or the audio read?

RedBook CDs were first created to store audio data. The disc would spin at a constant read rate and data was sequentially read from it. The TOC at the very begining of the disc would guide the cdplayer on where to point the laser for if you skip tracks etc.

This was how the CD format was concieved. Mind you a wav file on a cd has identical problems to standard redbook format. There'll be read errors and there'll be ECC to fix them thus creating slight differences in sound. The way computers read data (busting data and processing in chunks) induces it's own jitter similar to ECC in cdplayers.

So the point becomes why store it as data? To eliminate jitter induced problems you need to buffer the data and clock it out acurately, not change how it's read.

 

[Senn20]

Quote:

Originally Posted by trains are bad I have a basic grasp of how the audio CD works. It seems to work, but the absence of an embedded clock signal seems week to me, but apparently it works. Anyway, my question is why? Why not have some kind of audio file, PCM or otherwise, on the CD, which is read and played back by the playback device, like how my car CD player plays mp3s burned to a disk? Why attempt real-time playback at all?

The compact disc was invented back in the late 1970's. Audio "files" didn't exist. Real-time playback was the only option for a digital audio format.

Real-time playback works just fine.
Quote:

Originally Posted by trains are bad Is it because technology was different back when it was created? Is it DRM motivated? Could it possibly be that the idea of embedding an audio waveform on a spinning disc, to be played back in real time, was too ingrained?

Er, yeah! DRM didn't exist either. It wasn't because of force of habit, it was the only way to do it. Besides, why introduce another unneeded step into the chain by having to process clusters of information once you've retrieved it from the disc?

Quote:

Originally Posted by trains are bad I just don't understand what the point is.

CDs were more durable, more convenient, with better dynamic range and detail than any music storage medium available at the time. That's why they became popular.

But by all means, feel free to go back to cassette tapes.