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24/192 music downloads make no sense

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Re: 24/192 music downloads make no sense

#161

Post by Hello71 »

gwbas1c wrote: post #158

This article really misses the facts of the Nyquest-Shannon theory. In order to decimate a signal to 44.1 or 48khz, and preserve high-frequency content, high frequencies need to be phase-shifted. This phase-shift is similar to how lossy codecs work. For what it's worth: I'm a big fan of music in surround, and most of it comes in high sampling rates. When I investigated ripping my DVD-As and Blurays, I found that they…

no, it addresses it fairly clearly (albeit briefly):

> So the math is ideal, but what of real world complications? The most notorious is the band-limiting requirement. Signals with content over the Nyquist frequency must be lowpassed before sampling to avoid aliasing distortion; this analog lowpass is the infamous antialiasing filter. Antialiasing can't be ideal in practice, but modern techniques bring it very close. ...and with that we come to oversampling.

if you accept that the limit of hearing is around 20 kHz, then you must also accept that frequencies above that can freely be removed without loss of fidelity to the human ear.

the article notes that higher frequencies can be heard, but only in the form of ultrasonic intermodulation distortion. (i.e. not in fact the higher frequencies at all)

Re: 24/192 music downloads make no sense

#162

Post by xiphmont »

TheOtherHobbes wrote: post #134
ska wrote: post #55

Earlier quoted context omitted.

The article is pretty clear about this too - higher bitdepths and sampling rates can be quite useful in mixing and recording situations. They're pointless for playback.

No they're not. And no matter how many times this gets linked to on the Internet, it's still wrong. The basic problem: the quieter a sound or detail gets, the fewer bits of resolution are used to represent it. In 16-bit recording, there simply aren't enough bits to represent very low level details without distorting them with a subtle but audible crunchy digital halo of quantisation noise. In a 24-bit recording, ther…

> No they're not. And no matter how many times this gets linked to on the Internet, it's still wrong.

The article is still correct, just like it always was.

Ironically, most of your analysis is also correct. Somewhere in your understanding though, you're leaping sideways to an incorrect conclusion.

>The basic problem: the quieter a sound or detail gets, the fewer bits of resolution are used to represent it.

So far so good, but you're about to go wrong again once you start thinking in terms of stairsteps and boxes and looking instead of hearing.

Back to the bits.

What lower amplitude (and fewer used bits) means is that the sound, as represented, is not as far above the noise floor as a full-amplitude sound. The digital noise floor is completely analogous to, eg, the noise floor of analog tape. If you use a dithered digital representation, you get something that behaves exactly as analog does. You hear and perceive both the same way.

>In 16-bit recording, there simply aren't enough bits to represent very low level details without distorting them with a subtle but audible crunchy digital halo of quantisation noise.

On an audio tape, the magnetic grains are just too large to represent very low level details without distorting them with a subtle but audible crunchy halo of analogue distortion and hiss.

In a 24 bit recording, the noise you mention is still there! It's just shifted down [theoretically] 8 bits or -48dB. That's the only difference. The noise floor is lower.

[In reality, 24 bit isn't. Most recordings don't even hit a full 16 bits, and no recordings, unless they're mathematically rendered, can get deeper than about 21 bits. There is no such thing as a 24-bit audio ADC/DAC that delivers 24 bits. The very best available today are about 21 bits of signal + 3 bits of noise.]

So the difference in playback between 16 bits and 24 bits is about 5 actual bits. If you're complaining about soft sounds in a 16-bit recording 'not having enough detail' because they're down at, say, 3 bits of resolution, are you saying it's all fixed by using 8? Aren't 8 bits woefully too few for any kind of quality sound?

(I hope at this point, you realize you're barking up an incorrect tree)

If you're following me so far, we can continue, but I expect even this much is going to require more conversation.

Re: 24/192 music downloads make no sense

#163

Post by itp »

gwbas1c wrote: post #158

This article really misses the facts of the Nyquest-Shannon theory. In order to decimate a signal to 44.1 or 48khz, and preserve high-frequency content, high frequencies need to be phase-shifted. This phase-shift is similar to how lossy codecs work. For what it's worth: I'm a big fan of music in surround, and most of it comes in high sampling rates. When I investigated ripping my DVD-As and Blurays, I found that they…

When you say

> In order to decimate a signal to 44.1 or 48khz, and preserve high-frequency content, high frequencies need to be phase-shifted.

What do you mean by high frequency? If you mean frequencies below but near the Nyquist frequency then no, there is no phase shift. If you mean at or above...

I'm struggling to avoid a blatant appeal to authority here, but your position is that the author of the Ogg Vorbis coded doesn't understand digital sampling, which seems challenging to believe.

Re: 24/192 music downloads make no sense

#164

Post by nandemo »

splitdisk wrote: post #36
jchrisa wrote: post #28

Earlier quoted context omitted.

Have you tried listening to SACD? The high sample rate might not give you more reproduction of audible frequencies, but the difference in arrival times it can encode makes well recorded stereo stuff more interesting to listen to, in my limited experience.

I would be very curious to listen to SACD on some good headphones in a quiet room. Not sure if I've ever even seen a SACD player aside from maybe in the Sony store 10 years ago. The trick would be to find something that would be mastered for the format.

Are you sure? Many so-called "universal" bluray players can play SACDs.

I got a Denon one. I haven't played any SACD on it yet (I got it for bluray), though I guess I could easily find some at that video rental store (in Tokyo).

Re: 24/192 music downloads make no sense

#165

Post by Franciscouzo »

Hello71 wrote: post #160
alkonaut wrote: post #132

Earlier quoted context omitted.

Doesn't that depend on what type of playback you are doing? More and more playback these days is done via digital transfer with the volume set in software at the sending end, to amplifiers at fixed volume, such as many multi-room systems. If I airplay a song from my iPhone and have the volume at 50% set in software, then a few extra bits can help. Not sure if it makes a noticable difference, but it's a digital mixing…

no, because if you play at lower volume, that simply means that the quietest parts are closer to (or underneath) the threshold of hearing. I see it this way: let's say 16 bits is needed to represent the entire discernable dynamic range between the threshold of hearing and the threshold of pain. if you turn the volume to 50%, then you throw out 8 bits, but you also only need to represent 8 bits worth of hearing range.

turning the volume %50 down would yield 15 bits, not 8 bits, which would be discernible.

Re: 24/192 music downloads make no sense

#166

Post by beat »

ska wrote: post #135
TheOtherHobbes wrote: post #134

Earlier quoted context omitted.

No they're not. And no matter how many times this gets linked to on the Internet, it's still wrong. The basic problem: the quieter a sound or detail gets, the fewer bits of resolution are used to represent it. In 16-bit recording, there simply aren't enough bits to represent very low level details without distorting them with a subtle but audible crunchy digital halo of quantisation noise. In a 24-bit recording, ther…

If your mastering is done competently, you really aren't going to be able to hear it in a realistic scenario. Which is why: "Talking about dynamic range completely misses the point." isn't really sensible. It's the use of dynamic range that decides how much useful resolution you have when quantizing a signal. This is really why higher bit depths on record and mixing are useful - they let you be sloppier with the inpu…

Mastering, especially modern mastering, compresses the bejesus out of the end product. Trust me, you do not want to listen to uncompressed recordings under real-world conditions. Details will be so quiet you can't hear them. It'll sound thin and dull. Most modern pop has maybe 5-6db of dynamic range. Really loose, open mastering will be 20db or so.

As someone who both records/mixes albums and a live-instrument musician, a live instrument in the room sounds utterly different than any recording. Not necessarily worse, just different. The pursuit of "accuracy" in audio playback is childish and naive. The sound of a recording is a function of technical limitations, compromises, and aesthetic decisions as much as it is a product of the raw source sounds. Don't make it sound accurate, make it sound GOOD! And that usually means a lot of compression, and often deliberate distortion.

Re: 24/192 music downloads make no sense

#167

Post by beat »

earlz wrote: post #119
shmageggy wrote: post #113

Earlier quoted context omitted.

Mastering for vinyl is very common in the industry. I don't have time to dig up a reference right now, but the medium has different constraints than digital so is usually mastered separately, especially for big budget stuff. The differing constraints are mainly that while CD has a hard amplitude limit (hence brickwall limiting), the constraint on vinyl is not hard in the same way -- it mostly has to do with amplitude…

My understanding is that with vinyl, if the signal has too high of an RMS at low frequencies the needle can literally skip off the groove, and for this reason vinyl can't necessarily be as compressed and loud..

Not necessarily, but full-power vinyl grooves would cause all sorts of distortion and misbehavior for the very mechanical nature of cartridges and tonearms. Likewise, high frequencies would be so small they couldn't really be picked up.

Hence the RIAA curve, which is an eq curve applied to the mastering before put to vinyl that reduces the lows and exaggerates the highs. It is reversed by the phono preamp during playback.

Re: 24/192 music downloads make no sense

#168

Post by S_A_P »

I just recently purchased Izotope Ozone 7 advanced. One feature it has is "codec preview" which lets you "solo" the codec artifacts for MP3 and AAC format. Even at high but rates it's amazing how swishy bit reduction sounds. It also made me realize what I was hearing with mp3s was artifacts from compression. That said, it's not unlike tape hiss or vinyl noise. In fact I think it can have its own charm and in some cases make the music sound more full. It's also probably why 24/192 digital audio can sound so "cold" or lifeless.

Re: 24/192 music downloads make no sense

#169

Post by beat »

hatsunearu wrote: post #10

The single worst thing that harms audio quality is excessive compression. It's ruining everything, I'd say. Heck, I'm sure everyone who knows their worth would agree that compression harms audio quality. Recommended reading: https://en.wikipedia.org/wiki/Loudness_war edit: compression as in dynamic range compression, not data compression like mp3 in audio

I've played acoustic and electric instruments for over 30 years, and recorded numerous albums.

Compression is the best tool we have for accurately reproducing the musicality and emotion of a musical performance. Without compression, most recordings would be unlistenable.

Don't confuse the foolishness of the loudness wars for "compression is bad". That's like saying the internet is bad because there's porn on it.

Re: 24/192 music downloads make no sense

#170

Post by beat »

S_A_P wrote: post #168

I just recently purchased Izotope Ozone 7 advanced. One feature it has is "codec preview" which lets you "solo" the codec artifacts for MP3 and AAC format. Even at high but rates it's amazing how swishy bit reduction sounds. It also made me realize what I was hearing with mp3s was artifacts from compression. That said, it's not unlike tape hiss or vinyl noise. In fact I think it can have its own charm and in some cas…

From mastering records at home, I've found that in all but the most golden-ears focused listening, I can't hear the difference between 192 bit mp3 and 44.1/16 cd quality. But 128 bit mp3 is audibly degraded and irritating.

That's a pretty cool feature for Ozone 7, for sure! I'm still using Ozone 5 and don't feel a need to upgrade, but that might make it...

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