My recent article Face the Music: CDs Suck pointed to market forces that inhibit the arrival of a high-performance successor to the venerable and ubiquitous optical format.
As a part of my argument, I pointed to the arrival of the CD and its comparison with the phonograph record format. “The disc was convenient and smaller than a record. And while the CDs sound was compressed and didnt offer the acoustical range of vinyl, the digital format held the appeal of consistency; it could be played perfectly, perhaps indefinitely, without the creeping degradation suffered by the earlier record media.”
This last line drew howls of protest from many readers, even as they agreed with my thesis. And upon reflection, I regret the choice of verbiage.
Yes, I recognize that CD-Audio isnt compressed. Regardless, sampled sound isnt the same as real life audio (nor is vinyl, of course) and the sampling rate most often used for CD-A is not the ultimate in sound reproduction. Progress on that front is captive to the established format and the market around that format.
Many readers offered excellent points on the subject, as well as asking “what was I smoking?” Without further ado, heres a sampling of those responses:
“The CD format is not a compressed format. The MiniDisc is a compressed format, this is why it never really caught on in consumer circles. The audio-philes of the day were still intimate with their vinyl—they wouldnt accept a compressed format.
MP3 is compressed, but the only reason it has caught on is because of the time that has ensued since the demise of vinyl. Enough time has elapsed that the public has become divorced from the technology. MP3 is simply accepted. The technology is trusted because it is not generally understood.
CD audio is comprised of 16-bit samples that are taken 44,100 times per second. Each 16 bit sample is split into 2 eight-bit words. Since the CD standard demands that at least two zeros be between each one, each 8 bit word is exchanged with a 14 bit word (EFM, or eight-to-fourteen modulation). … [a long long technical explanation of CD signaling followed] … The speed of the disc starts at about 500 rpm in the center and goes to about 300 rpm as the pickup nears the end. The speed is adjusted each time a frame is read due to the timing error that is calculated from the last frame.
Nowhere in any of this is the signal ever compressed.”
Eric Stromberg, Senior Electrical Engineer
The Dow Chemical Company
Considering Audio CD Compression
and Dynamic Range”>
“I dont think its really accurate to say that CDs are compressed, although the MP3 files on them certainly are. Any medium is restricted somewhat by its format. CD audio is restricted by its 16-bit, 44-Khz design.
Similarly, vinyl is restricted by the properties of the vinyl as well as those of the needle and cartridge. Both of these face restrictions one or more places in the signal chain until it comes out the speakers, where they face the acoustical properties of the environment and the widely varying human ear.
More to the point, high resolution systems like Dolby Digital and DTS are also compressed (as is, I think, DVD Audio and SACD). If Im not mistaken the Dolby Digital and DTS sound at your local theatre comes off of a special purpose CD player, or at they least used to.
As a point of interest, I once read that the size of the CD was determined by what would fit in the dashboard radio in a car. It always irritated me that this restriction resulted in two CDs instead of one when the many great double record rock records of my youth—some of which were 20 or more minutes per side—were released on CD.”
“Um, Audio CDs are NOT, by definition, compressed (unless youre listening to an MP3 CD, which is a horse of a different flavor). CDs offer well over 90 db of dynamic range compared to vinyls 45 db or so. Granted, this dynamic range may not be fully utilized by the producer, but thats a human decision, not a limitation of the technology.
A CDs frequency response is theoretically limited to just over 20KHz, only a dream for vinyl. Early CDs suffered from poor Analog-to-Digital conversions which could make them sound gritty or overly bright. But such is not usually the case today.
Most of the bad sounds found on todays CDs are the result of poor engineering or lousy performances. What many people miss on CDs, indeed, in digital recordings of any type, is the DISTORTION inherent in most analog recording systems.
When presented with excessive signal levels analog devices typically saturate gracefully while digital devices run out of bits (a bad thing). Moderate levels of this saturation produce the “fat” analog sound so many find pleasing. This is why so many high-end recordings are now made with analog devices in the signal chain: to warm up that sterile (real) sound with analog distortion. We corrupt the signal to make it sound better!
While Im no great defender of the CD we still should be honest in our characterizations of it.”
Richard Thompson, President
: Its not the format thats the problem, its your hearing!”>
“One quick thing worth noting.—the “tyranny of the installed base” of CD-Audio is only one part of the equation. The other part is how difficult is it to upgrade to support the new features of the new formats, and whether the consumer sees the need for it.
Moving from vinyl to CD was a no-brainer, which is why it went pretty quickly—the audio quality difference was significant. But it was still just a stereo signal that required no new speakers or amplifier with special decoding capabilities.
DVD-Audio has the benefit of higher fidelity, which for many is not significant, and holds more songs per disc, which is its primary benefit. SACD (and DVD-Audio, too?) adds additional channels and encoding to the mix. The problem here is that it requires more equipment to take advantage of the new features, and for many people that is not practical.
Besides, where do people listen to music discs? A large percentage use portables with only stereo headphones or carry-arounds with only two speakers, usually of middling quality, so the extra channels and encoding are lost.
Cars are the best place. But this requires significant investment for older cars, not much in new cars, and in either case, road noise and other sonic distractions mean some of the additional goodness is lost here as well.
Home is where you can get the best audio setup. But even then, how many households are going to have multi-speaker setups and be willing to buy the equipment to process the new format for full usage of the formats capability? I dont have surround-sound even, and of the people in my social circle only a few do.
Part of the problem is the house itself—without extensive changes its not practical to wire a room for multi-speaker setups. Maybe when wireless technology is improved enough for remote unwired speakers, can the mulitchannel formats take off.
Anyway, CD-Audio is good enough in quality, but doesnt hold enough songs per disc. Should that hold us back? No!
I dont think SACD is going to make it in the long-run, much like MiniDisc and MemoryStick. Sony has been trying to lock into a licensing goldmine but seems to fall short each time.
DVD-Audio I think has a great shot. But the MP3 CD will be a tough competitor because it works on computers, inexpensive portable players, and most DVD players. The ability to hold so many more songs per disc is also a huge benefit, and while compression is an issue, its often at the choice of the user what bitrate (sampling rate) to use. This ability to choose your own bitrate is part of whats made it so popular.
Is it more important to get the most songs on your MP3 CD or to get as many as you can without sacrificing quality? I like that choice. So in that case, its good enough for me to buy my CD-Audio discs and rip em how I want em, and know that I can play them on a variety of devices.”
“I think that the Compact Disc became such a successful format not only because of its more convenient size and superior resistance to damage and deterioration, but also because the signal-to-noise ratio is so much better than vinyl. While the frequency response of analog recordings certainly exceeds that of CD-Audio, the vast majority of consumers dont own audiophile-quality playback equipment, dont usually listen to music critically, and consider the noise inherent in vinyl (pops, clicks and groove wall noise) more annoying and distracting than a compressed frequency response. Consequently, the CD became an unqualified success, despite the overwhelming installed base of turntables.
As for the newer formats (DVD Audio, SACD), I think the reasons why these formats have not yet made inroads are three:
- For the masses, the improvement in sound quality isnt great enough to justify the purchase of new playback equipment (quality of consumer-grade gear; nature of mass-marketing listening habits).
- For the techno-geeks, the use of (largely unnecessary) copy protection measures such as watermarking and prohibition of digital output, is off-putting.
- The relatively small segment of the market that is audiophiles who will endure any inconvenience or additional expense to obtain the highest quality music playback is insufficient to ensure the success of any format.
I believe that until the recording companies replace the CDs they current manufacture and distribute with high-resolution, multichannel discs that are (a) not copy-protected, (b) will play in conventional CD players (in standard CD-Audio quality stereo), and (c) for the same price as standard CDs, the 20-year-old CD-Audio standard will continue to dominate, and the new formats will languish.
As for departure from the current optical disc—maybe when flash memory (Im partial to Compact Flash, myself) reaches DVD capacities?”
William J. Austin