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How many bits, how fast, just how much resolution is enough?


BlueSkyy

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If I'm not mistaken the points are joined using some form of interpolation and the more points you have/take the more accurate curve will be reconstructed.

 

images?q=tbn:ANd9GcT0Fpl447omsfz5jZ8x09fjz07nHtFBYchU4IcZewtclpmtWWyQ

 

R

 

You are mistaken. See Nyquist.

 

The bit depth matters, of course. Sample rate does not once it is sufficient for the input signal.

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several reasons to (maybe) buy a higher bit rate/depth recording:

 

#1 by far is that, just maybe, they took greater care with the recording mastering etc. process before it got to the consumer level - you'd have to check to be sure

 

#2 filtering may be easier/less intrusive as I alluded to above - this is mentioned in that article by "monty" tho I downrate things without a Methods section, or by some dude on the internet - to be taken seriously, your name and affiliation will appear at the top of your peer-reviewed article

 

#3 - um... ah... I thought I had a 3rd one last night...

 

1. Some labels release a high-res "studio master" version. This is as good as it gets. Other formats may have been subjected to additional mastering (aka mangling). When such a studio master version is available, it's the one I get unless it is hideously priced. In some other cases the high-res versions are merely upconverted from CD and a complete waste of money. As you say, check to be sure.

 

2. I know Monty. He's the real deal.

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Since I never spoke of sample rate, let's consider 16/44.1 vs. 24/44.1.

 

Doesn't higher bit depth lower the noise-floor?

And if the noise-floor is lower, don't we get increased resolution?

 

I still don't understand why everyone keeps talking about sample rate...

 

R

 

Yes, higher bit depth reduces the quantisation error. With dither, the error is mainly wideband noise, possibly shaped. Without dither, it becomes harmonic distortion. Either way, more bits gives less error.

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Let us say I have a 24 bit master and way down around 101 db, there is a very faint conversation caught on the recording. Everything else captured has a maximum dynamic range of 30 db.

 

If I down sample this to redbook, I will no longer hear the conversation, but the wave form that remains should be identical?

You wouldn't hear that conversation in either format.

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Compared different systems but not resolutions as resolutions.

 

I don't know how to create identical hardware for 44/16 and 192/24 that need for comparing of resolutions.

Easy. Using a high-res source, apply the same low-pass filter and dither you'd use for a conversion while leaving the result at 192/24. Feed the original and the filtered data to the same DAC with the same settings.

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Of course it is. Imagine two equivalent 10 KHz pure analog sinusoidal tones, one started 100 microseconds before the other. A digital (PCM) 44.1 KHz sampled recording of this will sound different from a higher res digital recording..

 

What makes you say this?

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No doubt about that. But it isn't all about frequency response. There are other criteria that define fidelity.

 

Yes, there is also non-linear distortion. The only distortion inherent in PCM audio is that caused by quantisation, and this is readily addressed with dither.

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I've read that page a few time over the years and always come to the conclusion that Monty wants to have it both ways.

 

1. High resolution is actually harmful and this can be heard.

 

2. Nobody can hear high resolution and it's proven by tests.

 

I think you're being disingenuous. He's saying that since we can't hear high frequencies, reproducing them unnecessary. Moreover, attempting to reproduce them anyway can cause distortion in the audible range, something which is readily demonstrated.

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I mean two *analog* tones of 10kHz, with (very slightly) different phase relative to the recording microphone..

Still too vague. Do you mean two tones simultaneously (which isn't a thing) or a single tone recorded twice with a slightly different phase relative to the sampling clock (this is readily simulated)?

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...that you cannot implement exactly in real world. It only conveniently assumes infinitely long signals with filters that are infinitely long ,so that nothing ever comes out of the filter, because it also has infinite delay. And assumes infinite precision of timing and resolution of the samples. But other than that, yes, it works nice...

 

 

 

IIRC, pretty heavily oversampled converters. Which makes pretty big difference...

 

Here's 19k sine wave from a NOS DAC running at 44.1k sampling rate:

[ATTACH=CONFIG]31158[/ATTACH]

 

And the same source data, same DAC, but now upsampled to 384k sampling rate before sending to the DAC:

[ATTACH=CONFIG]31159[/ATTACH]

 

So you certainly want to have the conversion running at higher rate than 44.1 kHz...

 

 

P.S. DPO-scope is good way to see how stable the waveform is, which also tells quite a bit about the reconstruction that you don't see in old-school scope.

Your figures prove that the 44.1 kHz sampled signal contains everything needed for accurate reconstruction. That incorporating a digital processing step aids in producing a quality output is completely beside the point.

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It's beside the point you are making (that more samples aren't needed to accurately represent the waveform), but is possibly still quite relevant to the OP's question about whether a higher sample rate makes for better digital audio.

 

Can we agree that the engineers who designed 8x oversampling into DAC chips decades ago did so for solid engineering reasons? And if that's granted, then can we go from there to saying there is no engineering reason for a decimation-interpolation sequence in the middle of the recording/playback chain, but this exists solely as an artifact of the way the music industry has evolved?

 

There's a solid reason for that: it saves tremendous amounts of storage space and transmission bandwidth.

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Oh, I've seen many claims that human eyes are not accurate enough to tell difference between 1080p and 4K...

 

Depends on the size of the screen and the viewing distance. With sizes and distances common in most homes, even 1080p is beyond what most people are able to resolve. Besides, most streaming content doesn't take full advantage of 1080p. The difference between Netflix and a good Bluray can be quite striking.

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For example, I can fairly reliably tell a difference between a Tidal 16/44 file and a digital 16/44 copy of the same file on my NAS.

 

How do you know you're listening to the same file? It could be different masters or different down-conversions from a high-res format.

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Sounds like a candidate for Amazon's unlimited storage at $60 a year. :)

 

(Is that available outside the US?)

It's officially available in the UK (at roughly the same price), and anywhere else if you register an account on amazon.com rather than a local domain.

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I have 2.5 meters and 50" 4K TV. I'm not so much interested on movies, because I don't watch much movies. But I use it for watching photos taken with the DSLR. And I can tell that there's a pretty huge difference between 1080p and 4K versions. And yeah, different image scaling algorithms also make difference (regardless of display).

At that size and distance seeing a difference is no surprise.

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Can You show (or at least tell) how the filtering differs when it is feed from 16/44 or 24/44 signal?

 

A typical DAC will pad input of any size to it's internal processing size and use the same filters for everything. A 16-bit-only DAC likely uses lower precision calculations or there'd be no reason to restrict it to 16 bits in the first place.

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