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The very best in obsolete and failed technology...
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Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 94,785 Mod ✭✭✭✭
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Don't bother reading if you weren't in that CD vs something sound quality debate. Trying to do some mythbusing here.
No, that is nonsense.
It is an indisputable fact that CDs are technically capable of capturing sounds more accurately than vinyl. Whether a CD actually sounds better comes down to how well the recordings are mastered.
CDs capture a digital representation of the sound, but as long as the sampling rate of the sound is twice the range of frequencies you are capturing, the sound will be captured completely accurately, with no loss from converting analog sounds to a digital representation. This is the Nyquist-Shannon sampling theorem
Since most humans can only hear a range of about 16kHz, you would sample at 34kHz to get a perfect (to human ears) representation. CDs sample at 44kHz to give a bit of wiggle room.
I don't know how far back this debate goes, after a few pages I got bored so I don't want to seem like I am picking out yourself.
Anyway, Dempsey was right in a sense about 44.1 capturing a sense of a sound. The Nyquist-Shannon theory is correct however the point about using a higher sample rate is not about hearing a large range of frequencies. Alias filtering will still cut that down as it does in 44.1 but the debate about sample rates comes down to the how the sound in the audible range is chopped up. The sound a CD produces is not as plainly accurate as is perhaps being made out.
Sampling at nyquist rate is the minimum sampling rate you should use in any bandlimited channel.
CD's sample @ 44.1KHz and DVD audio sample @ 192kHz, care to guess why?
That is the key. Regardless of the sample rate being used, the result is still a bandlimited signal. With alias filters mentioned earlier, the extra sample rate above and beyond 40kHz allows for a better quality filter to be applied. Which is in addition the the "chopping" thing I crudely mentioned earlier and talk about later.As Capt'n Midnight said, it's mainly due to storage space, it's sampled at that rate simply because it's possible. Research has shown that very very very select few people can actually hear any difference in 192kHz audio.
And you mentioned earlier about the limitations of 16 bit, the bit depth refers to the dynamic range of the audio. 16 bit allows a 96dB dynamic range, and given that the quietest ambience rooms people would be used to would be 20-30 dB, and the fact that 120dB is the threshold of pain, a 96dB dynamic range is plenty.
Film sound is recorded at 24 bit which allows a 144dB dynamic range, this allows a much lower noise floor since films are played really loud in cinemas, so it allows a lot more head room.
A couple of things here. About Sofaspuds noise floor point, no. About it just being about dynamic range? Not quite. But think about where the noise floor is coming from. Maybe you already do but you didnt say it.Yep, the storage size is the driving factor. 44.1kHz is the minimum sampling rate when the receiver is the human ear, lower than that and the losses become very noticeable.
Why would DVD Audio want to cover frequencies not detectable by the human ear? Why not stay at 44.1kHz if the audio is 'perfectly fine'?
Because a live performance is actually not limited to whats detected by the human ear & its a continuous signal, not sampled. Capturing more information requires more storage space. What you get on a CD is a trade off between audio quality & capacity and the audio quality is set to a minimum really so more 'minutes' can be fitted onto a CD
My question was to debunk this idea about Nyquist rate
I knew the answer to the question I was asking
Think of the human ear as a window filter. Not everyone can hear the same frequencies, especially at the upper & lower limits.
As touched on, there is a misunderstanding about what a 192kHz signal is giving you, and it is not more frequencies being presented to the listener. Storage size has something to do with it, but not in the way you guys think.
I wanted to quote all the posts as I didn't wanna pick out anyone in particular.
The Reason for 44.1
44.1 is not a sample rate derived purely for audio, not directly anyway. It has a weird roundabout way of getting to 44.1. Back when it was being conceived, there were problems recording the high quality digital audio. The CD was a playback medium after all. As it happens, Sony and Philips (along side developing the CD) developed a device which turned PCM audio (what goes into a CD) into a pseudo-video signal for video tapes. Red-book CD and the PCM adapter came out at the same time.
This is important as when all the mathematics is done, taking into account the video tape standards of the USA and Europe and of course Nyquist and Shannon, the amount of audio samples which could be placed onto a single frame on a video tape is 44,100 at 16 bit depth. This caught on to the point that it was adopted for CD.
The Higher Sample Rate Debate
Higher sample rates do not give you more frequencies to listen to. They allow a greater space for the aliasing filters to work. Not only that, they help with this chopping thing.
The chopping thing can be looked at with bit depth.
16 bits gives you 65,536 levels to assign the volume (amplitude) of a signal. So, if I am speaking the computer will decide which level I get assigned to. The problem here is that the process creates errors, which creates noise which ties into the noise floor point.
The reason for 24 bit depth is not because it provides you with a low noise floor as such, it gets rid of the noise being created by that amplitude level decision. The reason for this is that 24 bit has 16,777,216 of these levels. In the studio for recording I use 24 bit but 32bit for mixing because, as you can imagine, adding up loads of signals in 16bit which are getting this error can build noise easily. Incidentally, 32 bit has 4,294,967,296 levels.
The same can be seen in the sample rate. 44.1 is chopping up the frequency of the sound we hear (not amplitude) 44,100 times a second and the digital playback joins those dots together. By using 192,000 snapshots a second the dots can be more accurately joined. More practically, 48,000 snapshots per second seems to be getting a supportive following. So, the use of higher sample rates is not about hearing higher frequencies, it is about making the frequencies we do hear get their respective dots joined up by someone decent at it and not a toddler.0 -
And then there was the Iomga Zip Drive....
Back when I started college, and had access to the internet for the first time, the only way you could bring all of your midi files, FORTRAN code and ascii art home was though a 1.44Mb floppy. Enter the zip drive.... 100Mb of portable storage per disk, parallel port connection, was a dream come true.... for about a year...
G'way with that, the Jaz disk was where it was at. 1gb portable disk in 1995, fook yeah :cool:
And quite the flop too!0 -
I think that it has something to do with a fax being considered a legally binding document which is difficult to intercept and forge and produces an instant hard copy!Every bank in the country still uses fax machines. So do the big insurance companies and the businesses in the IFSC
Every year multi million pound transfer deals for football players have to be faxed in before a deadline
Fax is far from dead and will be around for a long, long time
Emails don't0 -
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SEPT 23 1989 wrote: »Concorde
I raise you one Tu-144, well I would if I hadn't just read the entire thread and realised someone beat me to it pages ago, while Concorde wasnt quite the technological failure, it wasn't exactly an economic success. Whereas the Tu-144 which preceded the concorde was more or less a complete, if not interesting failure, so you could say both are obsolete and technical evolutionary dead ends in aviation. Surpassed by events, oil crisis, and before they got off the ground, the original and defining aircraft of decades to come was already off the ground (747). So it/they kind of are obsolete and failed.Hah - still got that Creative Zen Vision: M meself. And I can tell you I felt the same way when I got it way back in 2005
I should have gotten one of those creative zen jukebox, I think they look pretty cool. They seemed to be rapidly displaced by ipods?
I went and got a minidisc player right before the release of mp3 players like the zen, Id heard nothing of mp3's impending release and was ridiculed by a mate (all in hindsight) for throwing away money on a minidisc. I hardy used it and I thought at the time it was fairly limited, had to use the sony software, couldnt import other file formats? as I recal. I got rid of it after mp3s were well known still for a tidy enough sum (but well less than what i paid) and didnt replace it. The guy that bought it off me must've been some diehard mini disc fan or maybe he thought mp3 players would be a flash in the pan. Thankfully I wasnt the only one after all, so maybe mp3 was a big secret as I had suspected all along .
Ive seen nor heard of either since.Digital compact cassette player. Had one in our home back in the day.
I think this is up there as a potential winner, just because I never even heard of it.Capt'n Midnight wrote: »TU95 isn't merely a prop aircraft. It's another Russian example of stuff that shouldn't work but somehow does.
Turbo props are more efficient at speeds around Mach 0.5 , this is why short haul commuter aircraft use them, as do slower military transports and patrol aircraft. But get any faster and they are dreadfully inefficient.
The Tu95 has a dash speed of Mach 0.87 and from it's normal cruising speed it can out-accelerate most interceptors. Which should be impossible since that would mean the propellers are running at supersonic speed. They do, and it's VERY, VERY LOUD.
Its merely a turboprop, not sure why it should not work? Turbo props were chosen because they provided better efficiency and allowed longer range than turbojets and better reliability than piston engines at the time for what was available the the manufacturers. The speed the aircraft could develop, wouldnt be related completely to the tip speed of the props, dont know what the operating range of the prop was, but if the tip speeds exceeded supersonic it would increase aerodynamic inefficiency, and could lead to damage, cant see the advantage, the Tu-95 does not belong in this thread. 0 -
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Palm VII.
http://en.wikipedia.org/wiki/Palm_VII
Wireless PDA. Only ever worked in a couple of states in the US. Well ahead of it's time though.0 -
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