CD audio is not good enough, CD Standard is bad quality
CD audio is not good enough, CD Standard is bad quality
May 1 2003, 04:29
Group: Members (Donating)
Joined: 7-April 03
From: Newark, CA
Member No.: 5871
Sound quality is a complex subject, and one that has been thrashed
out elsewhere time after time. Nonetheless I'll give it a bit of a
spin here, without getting all technical, in order to justify why I
think CD audio is not good enough.
When I complain about CD sound I am not doing so as some sort of
retrograde vinyl lover who can't change with the times. :-) I am
simply saying that the sound of the CD I am listening to has audible
problems and does not match what I expect the creators wanted. This
can be measured by how closely the CD replicates the master. Of
course in most cases I don't get to hear the master, so much is
guesswork. However, as a trained audio engineer I have *some* idea of
what is expected and can certainly compare CDs to the masters I
CDs improved on vinyl in many ways, notably in reduced noise floor,
phase artifacts, and crosstalk; ease of handling; and accurate
handling of low frequency stereo information. But CDs are inferior to
vinyl in frequency response and degradation characteristics. If a CD
gets a scratch you hear unlistenable white noise; if a record gets a
scratch you hear a DJ. ;-)
Going further, some may "prefer" the sound of vinyl precisely because
of the distortions it introduces. These include rounded signal peaks
and second-order harmonics, as well as the aforementioned phase
issues. All of these introduce a "warm" sound that is palatable to
many. Whether I like that sound or not, I prefer to hear what the
artist intended. If they wanted harmonics they could have used a
tube. And so on.
A bit more is in order about error correction. Most errors are
corrected by CD players, but this can produce tiny glitches of noise
that most people do not notice. I notice them. It's not that I have
better ears; once I point them out you can hear them as well. Of
course, the better the music reproduction system the more noticable
these are. (Though contrary to this, the better the CD player error
correction, the less you'll hear.) For most people with crappy
stereos it's not an issue.
I do not think that there is anything inherently wrong with digital
sound encoding, only that the 44.1KHz sampling rate and 16 bits per
sample are not good enough. Currently, studios use 96KHz and 24 (or
32) bits throughout the recording chain process, and must reduce this
down to consumer standards for replication. There's probably a good
reason why those people most highly trained in listening don't think
CD quality is good enough for recording. It's simply because their
ears tell them so.
You may be interested to know that the current CD standard was a
matter of much compromise between the American, European, and
Japanese manufacturers. I can remember reading some of the research
articles at the time (I was in university). The Japanese insisted
that 100KHz and 24-bit (if memory serves on the exact numbers) were
required for accurate reproduction. But the others argued that no-one
would hear the difference and it would reduce cost and time to market
if the lower standard was adopted. And so, unfortunately, it was.
Another big problem with many CDs is the terrible job of mastering.
Back in vinyl days you really had to know what you were doing to
adjust the master tape to the deficiencies of the medium. There were
relatively few mastering engineers, but they knew their job. Today
almost anyone thinks they can master, and so they do... badly.
So the problems with CD can be summarised as: insufficient frequency
response, insufficient resolution, poor mastering, nasty error
characteritics, and cases that break all the time. ;-)
MP3s inherit all of these except the bit about the cases.
May 1 2003, 20:28
Joined: 1-October 01
Member No.: 137
Well, all there issues have been discussed here from some time, and most of them pretty thoroughly.
I strongly believe 44.1 KHz 16-bit audio is more than enough for transparent reproduction under real-world listening conditions.
About read errors in cds: as 2decided says, this is a non-issue as long as the cd you are playing is not badly scratched. Cds have redundant information recorded, so physical errors can be recovered 100% with no lost data at all, most of the times. Only when there are too many errors of the error is too big, the data can't be recovered, and it has to be interpolated to reduce audibility of the remaining error. Even then, this interpolation, if not constant, I believe is quite bening, or in other words, inaudible.
About using 96 KHz is all studios, well, I'd say this is not generalized. I'd say some use 96 KHz and some still use 44.1 or 48 KHz. I'd also say that 24 bits is generalized, but just useful for mixing and such, not as a release format.
About 44.1 KHz sampling rate not being enough today or filter limitations, any decent 44.1 KHz DAC is free of aliasing problems, frequency response problems, phase problems, ripple problems, etc, up to around 21 KHz or more. How many people can hear up to 21 KHz?
Also, this is the first time I hear a sampling rate of 100 KHz was proposed for the cd. I don't think that happened, but I could be wrong. What I know is that 14 bits were going to be used, because were considered to be enough, but at last, 16 bits were used for convenience, being exactly 2 bytes.
About dynamic range of cd-audio... Well, using flat dither, it is about 94 dB. Using noise shaped dither, it can be the equivalent of around 110 dB. Back here in real world, even 94 dB is more than enough. If you take into account the ambient noise in a quiet listening room (around 30 dB) and realistic listening levels (110 dB peak as much?), 94 dB is more than enough to cover dynamic range requirements. Not to say that you won't find any recording that makes full use of those 94 dB of dynamic range.
About mastering engineers saying that 96 KHz sounds better, I have read about some experienced ones saying that it sounds the same to their ears. Anyway, ever heard of expectation effects or placebo effect? I won't believe that 96 KHz sampled music sounds any different than 44.1 KHz sampled music to anyone until I see a rigorously performed blind listening test that proves it, up to this moment I have not seen any.
Edit: jitter is a non-issue in good (and most average) players, there are plenty of measurements that support this. Take a look at http://www.pcavtech.com
Edit: if today's cds are badly mastered, it is not a fault of the format.
This post has been edited by KikeG: May 2 2003, 00:10
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