24bit vs 16bit, the myth exploded!

Discussion in 'Sound Science' started by gregorio, Mar 19, 2009.
  1. JaeYoon
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    Last edited: Oct 17, 2017
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  2. Don Hills
    Done that. Clamped the outlet of a PA compression driver between my teeth. Made my eyesight go blurry and my teeth ache.
     
  3. ev13wt
    :)
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    You and me, we are going to make billions. :)
     
    JaeYoon likes this.
  4. RRod
    Tuning fork to the teeth does wonders for PRaT!
     
    JaeYoon likes this.
  5. OddE
    -I am a bit late to the party, but I'd just like to chime in that the Benchmark AHB2 is getting close enough for all practical purposes (and then some!) - they claim THD+N at -118dB or so at rated output. (Which is where you'd need to be at in order to take advantage of the offered dynamic range.)

    Obviously, you'd also be in severe pain and your ears wouldn't be anywhere near capable of relaying said range to your brain - but it would be there. (nevermind the horrific distortion introduced by any transducer driven that hard; again, you'd have other priorities. Like shutting the system down, for instance.)
     
  6. Cutestudio
    The original article is faulty in it's primary premise, something I have pointed out before to the blind.
    Dither is a statistical method and while your statement is superficially correct there is an important caveat: We are still representing the data in 16bit digital so the quantisation errors are still present.

    Logically then it means that any transient HF shape is still locked to those quantised steps, and therefore still the wrong shape. As a tone it's not an issue (it's a statistical method), but as a one off, non repeated shape, it's still quantised to the wrong shape. The question of whether this creates an audible effect can be addressed by the question: "Can we heard the difference between no dither and (the various types of) dither?" If we can, we must be able to also hear the error. My next point however makes clear that this error is also irrelevant.

    A good post but this is where theory and practice diverge. This thread is about the LSB, bit0, and the worries that swapping that bit for 8 bits (i.e. going to 24bit) may be required or not: i.e. it's about the details of the tiniest sounds. This theory is inapplicable to modern pop CDs however because they are all mastered in 15 bits, having thrown away bit 15, the MSB.
    There's even a very good chance that those loudest peaks of a symphony orchestra will be simply cut off.

    So while the discussion of dither and the misunderstanding of it's limitations is indeed interesting; as a subject I feel it's rather irrelevant to modern digital music. 286 pages on the LSB when the MSB went a long time ago: i.e. we've got a bigger problem that 16 bit dither at -96dB, a problem that's almost exactly +6dB in size.

    Interestingly I find most of life is like this, the elephant in the room is usually quite invisible. Today there are many elephants.
     
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  7. gregorio
    1. Unfortunately, you appear to have completely misunderstood how dither works and it's purpose. After the correct application of dither there is NO quantisation error, nada, none whatsoever, response is perfectly linear down to the digital noise floor.
    1a. "Logically then", the rest of what you say on this matter is nonsense because it's based on your misunderstanding of digital audio/dither. There are no quantisation steps in the waveform after conversion and it is NOT the wrong shape, regardless of whether it's a transient or any other waveform shape!
    BTW, it's not a good idea to call others "blind" when you yourself obviously have a poor grasp of the issue!

    2. I've got no idea where this assertion comes from, it's complete nonsense but at least it's original complete nonsense, I've never heard this one before. Where did you get the idea that the MSB is "thrown away" during the mastering process?

    G
     
  8. 71 dB
    Dithering breaks correlation between the signal and noise. It means errors can't be appointed to the signal, but they form dither noise which is a separate entity of the signal. Quantization errors mean noise that correlates with the signal. When you remove the correlation, quantization noise becomes, well just noise present with the signal.

    Well, yes. Signal + noise is not the same as signal alone meaning we have "wrong shape". To correct this you need infinite bits, infinite dynamic range in theory. In real life worrying about wrong shapes at this scale (16 bit) is meaningless.

    -120 dB.png

    Look at the magnitude spectrum above: I genereted 1000 Hz sinusoid, level -120 dB (amplitude 0.000001) at 32 bit mode. Then I made it 16 bit using shaped dither noise and the spectrum of that 16 bit signal is above! The 1000 Hz sinusoid is clearly there. If I amplify this signal by 50 dB, I can listen to it and hear (just) the sinusoid behind the dither noise. The sinusoid sounds pure, because it is very very pure. What in this spectrum shows quantization errors? Quantization errors (no dither) look like this:

    -80 dB.png

    I Generated 1000 Hz sinusoid, level -80 dB at 32 bit. Then truncated it to 16 bit without dither. This is pure quantization error. You see 3000 Hz, 5000 Hz, 7000 Hz etc. (odd harmonics) dominating as you would expect. Below the same sinusoid at 16 bit with triangle dithering:

    -80 dB dither.png

    The noise power is similar to the non-dither case, but the specrum shape is very different, because the dither noise doesn't correlate with the signal (that would cause harmonics).

    Huh? Are you talking about loudness war?

    Not on the CDs of orchestral music I have. Stop buying bootleg crap. :wink:

    I wonder who has demonstrated most misunderstanding of dither? MSB = + 6 dB of dynamic range. LSB = + 6 dB of dynamic range. They are equally important.
     
  9. TheSonicTruth
    "

    There's even a very good chance that those loudest peaks of a symphony orchestra will be simply cut off.
    Not on the CDs of orchestral music I have. Stop buying bootleg crap. :wink:"

    He may be right. My classical CDs are all original albums released in the mid to late 1980s, yet they all have rock DR values: DR11-13.

    I *know* that a typical symphony sitting features much greater actual DR swings than what was put on my CDs. *Something* was done to them!
     
  10. bigshot
    When people speak of the dynamic range of a symphony orchestra, they're talking about how loud it is from a close perspective. Put your ear right next to a trumpet or tympani and you'll hear some pretty loud sound. But in practice, the louder instruments are arranged further back and the recording is made from a little distance to get a more listenable perspective. The actual dynamics of an orchestral recording is in the same range as any other dynamic music- 35-40dB max. It isn't comfortable to listen to music with wildly exaggerated dynamics.

    I have one surround sound orchestral recording that has the stupidest dynamics I've ever heard. It's a violin concerto, and they arrayed the band all around the conductor in a circle and miked the conductor's perspective. Someone had the bright idea of placing all the instruments at the same distance from the mic. They put the tympani right next to the violin soloist, so every once in a while there's a massive kettle drum hit that blasts you out of your chair. Unlistenable.
     
    Last edited: Oct 18, 2017
    bidn likes this.
  11. TheSonicTruth
    Technique counts for something! lol
     
  12. RRod
    And here's a 1979 classical disc (Soundstream recording) with DR15. And here's a 1986 recording with a track with DR20, but of course DR is not really a dynamic range measure since you can add material and have the DR go down…
     
  13. pinnahertz
    The DR meter is a tool for measuring a very specific case of dynamic range, short term dynamic range that is strongly affected by loudness war processing. But it does not measure total dynamic range, that's not it's function..
     
  14. castleofargh Contributor
    you're telling it to the wrong guy ^_^.
     
  15. pinnahertz
    I know, but I'm also aware that he's not the only one here.
     
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