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Speculation On a Lossless iTunes Store
DrJenny writes "C|net UK has up an interesting blog post predicting that within 12 months Apple's iTunes Store will include a download center for lossless audio. This would be a massively positive move for people who spend thousands of dollars on hi-fi gear, but refuse to give money to stores that only offer compressed music — they could finally take advantage of legal digital downloads. The article goes into details on how Apple's home-grown ALAC lossless encoding relates to FLAC, DRM, and the iPod ecosystem."
Speculation On a Lossless iTunes Store
Lossless? I thought the iTunes store was a loss leader?
The theory of relativity doesn't work right in Arkansas.
From the blog:
"And now I have an inkling Apple will add lossless music downloads to the iTunes Store within the next 12 months."
Translation:
I have no fricken clue that this will ever happen, but because I think it'd be cool if it did, I'll go ahead and blog about it.
If someone says he and his monkey have nothing to hide, they almost certainly do.
Sorry, Nyquist's theorem states that you can accurately represent frequencies up to 1/2 the sampling rate. Assuming you are a human and not a dog, you can not hear frequencies above 22khz. As for 16 bit, nobody uses all that dynamic range anyway. So 16bit/44.1khz is entirely good enough for listening.
Now 24/96 has its uses if you're mastering something, so that any errors introduced in the mixing process are below the quantization error in the final 16/44.1 product.
Give me Classic Slashdot or give me death!
Enough with the 24/96 wet dreams. Yes, 24/96 does offer real advantages for mixing houses in terms of being able to normalize levels generated by different sources and reducing the complexity of filters. But 16/44.4 is perfectly fine for home audio playback.
What does >16 bits get you? More dynamic range. BFD. 16 bits gets you (realistically) 90+ dB of dynamic range. Unless your listening room has a background noise level of 20 dB or less (trust me, it doesn't), you're not even enjoying the true benefit of the 16-bits you have now.
What does > 44.1kHz sampling give you? Wider frequency response. BFD. Let's assume that most people have good hearing beyond 20 kHz (very few do). Let's assume that most music/movie content has lots of information above 20 kHz (some do, most don't). Let's assume that your speakers can reproduce signals above 20 kHz (some can, most can't). There is still the issue of how you get that > 20kHz info on your recording on the first place. You see, most microphones don't record signals out that high, and of those that do, they only do so over a very narrow angle. When we have tech that can produce mics that are omni-directional above 20 kHz for reasonable costs then maybe you'll have an argument.
Let's deal with the loudness wars before we start worrying about 24/96.
Human being the key thing here. What makes you think that parent is human?
On the internet nobody knows you're a dog...
Nyquist's theorem states that a wave of frequency f must be sampled at the rate of at least 2f in order for information not to be lost. So, yes, a 44.1kHz sampling rate can accurately reproduce signals up to 22kHz without loss of information, and since that's all we can hear, we should be fine. Right?
Well, not entirely. You see, if the source material contains frequencies above 22.05kHz, they will end up "aliased" onto another part of the frequency spectrum. In short, the extra high-end becomes noise. Information is lost.
Here is the important part, in practical terms. In order to prevent aliasing, the source material must be low-passed to remove the unrepresentable high frequencies. Low-pass filters are not perfect; in order to toss out the frequencies we don't want, we end up attenuating some of the frequencies we do want. Thus it is not uncommon for high-frequency rolloff to begin in the mid-teens of kilohertz, even though we're aiming for 22kHz as the corner frequency.
This causes a real, human-audible difference in the finished product, and it is practically impossible to avoid.
Now, with a 96kHz sample rate, we aim to squash all frequencies above 48kHz, and our non-ideal low-pass filter starts to work in the 30kHz range. The imperfections in the low-pass filter are only apparent at frequencies humans can't hear. The finished audio ends up sounding like the source material, with no human-detectable loss in fidelity.
This is why 96kHz is a good idea.
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