Zp 24/96

Hello
As a long time Sonos user, I swing by this thread every once in a while. I have posted several times advocating that Sonos should support HiRes files.
It became apparent that wasn't about to happen, so a while ago I invested in a dedicated media renderer in my main system, which allows me to listen to HiRes files. I still use Sonos for the rest of the house - in fact I recently added a Play 5 to my son's room.
In case anyone is interested, I'll share my experiences with HiRes. I don't do blind testing, but I do level match and use AB switching. When I began these experiments my entire music collection consisted of lossless rips of my CDs. My expectation was that I would prefer HiRes files to these lossless files. These are my conclusions:
1. There was no consistent preference for HiRes over lossless (ALAC)
2. There was no consistent preference for lossless over AAC
3. There was no consistent preference for HiRes over AAC

I found that in my case, what mattered far more than the format was the mastering quality of the file. I cannot emphasise this enough. For me it has been a bit of a revelation. I now spend more time trying to establish the 'provenance' of specific releases and then buy the one which I think stands most chance of being well mastered. This does lead to me having bought several versions of tracks, but for sanity's sake I delete the non-preferred versions from the library once I've made a judgement.

This leads me onto another topic (hopefully I will be forgiven for going off-topic, but I think it is relevant). I'm sure most of you know all about the 'loudness wars'. I was aware of it but hadn't really thought through the consequences. Over the last few decades, mastering engineers have progressively applied more and more compression, increasing the apparent loudness of music. Each successive 're-master' almost invariably means a more compressed version. This means that it is very hard to find a version/release of an album that uses even a fraction of the dynamic range offered by 16-bits. To say that we need 24-bits is a sad joke I'm afraid. A well-mastered 16-bit version will have more dynamic range than a more compressed 24-bit version.

Sorry for going on, I'll sum up my findings:
1. If you want to experiment with HiRes audio, build yourself a dedicated renderer and allow it to co-exist with your Sonos system.
2. Don't get hung up on the format (sample-rate or bit-depth). Mastering quality is far more audible.
3. Dynamic range is one clue (not a guarantee) that a particular release has been sympathetically mastered.

Lastly, a request: Does anybody know of a website or database which rates different masterings? There's lots of information on the Steve Hoffman site, but it's hard to sort the wheat from the chaff.

I didn't phrase it very well, I've edited that sentence

1. If you want to [experience] experiment with HiRes audio, build yourself a dedicated renderer and allow it to co-exist with your Sonos system.

I don't expect people to change their mind about HiRes formats just because of my opinion. But if they feel so strongly about it they can get on and do their own experiments. (OTOH, it cost me quite a lot of time and money to find this out for myself, so if anyone does take my word for it they can save that expense LOL)

That is, IMO one of the big cons with hires: the hype over the format masks the real benefits to be had.

In turn, this gives the potential for people to be ripped off: at least one of the major hires music suppliers was caught red-handed selling full resolution material that had been simply reformatted into a hires format. These were then sold, at a premium, as "hires" (although most people didn't notice until someone did some measurements on the files).

Arguably, "hires" is just a storage format, and only a part of the format is usable for audio, with the rest containing noise. In this respect, these converted versions could be argued to be just as "hires" as tracks that were directly converted from 24/96 (or better) masters. However, customers were rightly expecting something better, and that was not delivered.

The "better" in this case was a better quality of source master. The unhealthy obsession (and ongoing misconceptions) with "hires" storage formats obfuscates this. It's a distraction, and quite a pernicious one.

A site which did reviews of the different versions that were on the market (irrespective of the storage format) would be a good thing.

I suspect getting full and accurate information on the provenance of the released recordings is probably a major barrier. Whilst the possibility exists for record companies and distributors to recycle and resell old versions of music at a premium price by sticking a shiny new "hires" label on the packet, they are unlikely to open their records to this sort of scrutiny.

Cheers,

Keith

For those who still think "hires" audio (especially higher sampling rates) provides audible benefits, the following might prove a little sobering:

http://youtu.be/VxcbppCX6Rk

Cheers,

Keith

http://youtu.be/VxcbppCX6Rk

Surely the point of hi-res isn't just the higher frequencies, but rather the perceived overall increase in 'resolution' achieved by the higher sampling rates?

Surely the point of hi-res isn't just the higher frequencies, but rather the perceived overall increase in 'resolution' achieved by the higher sampling rates?

A 44.1kHz sample rate can fully capture all of the frequencies in 20kHz+ audio signal.

Fully!

It's not like there are any intermediate frequencies that aren't represented. Any frequency, from 0Hz to 20kHz (plus a bit) that you can name, is fully captured within a 44.1kHz sample rate. Within the frequency domain, and within those ranges, there is no additional "resolution" to be had. In fact the concept of "resolution" does not apply to frequency in digital audio.

The only thing a higher sample rate does is capture higher frequencies.

Cheers,

Keith

Not saying for one minute that I support the 'hires' argument, but it disturbs me that every time this comes up, everyone points to this one article, as if one persons views should be taken as gospel over all others...

One reason it's quoted is because the authors are renowned experts on digital audio. They are the brains behind a number of lossy and lossless audio codecs, including the one most commonly used for Hires formats.

The other reason is that they explain, very well, why most of the reasons given by supporters for hires are actually based on a misunderstanding of how digital audio works. He provides explanations and evidence to support these explanations.

I have also yet to see any meaningful counter-argument which points out any flaw in his article. To date it is the best, most accurate, description of the benefits (or lack of) of hires.

It bears repeating that these guys are some of the leading experts in the world on this subject. THAT is why we all should be reading this article and taking it's claims seriously.

Put it this way, if you were involved in a complex legal case, you wouldn't take the legal advice given by your mates down the pub over that given by one of the top lawyers in the country, would you?

Cheers,

Keith

Surely the point of hi-res isn't just the higher frequencies, but rather the perceived overall increase in 'resolution' achieved by the higher sampling rates?

You do not achieve "higher resolution" by using higher sampling rates. Since the Nyquist–Shannon sampling theorem definitively states that a sound wave can be perfectly reconstructed by sampling at a rate 2x the highest frequency, the only thing you achieve by increasing the sampling frequency is increasing the frequency range of the sound. Period.

Ignore the "jaggies" representation that you see in audio magazines, where the "jaggies" approach a smoother curve as you increase the sampling rate. This is a gross misrepresentation of the actual process. There is no "increase the samples and you get a better copy of the sound" process going on here. That is bunk invented by the ignorant and the snake oil peddlers. The actual science is quite different.

You're right, I should have tought about it better.

Never been challenged yet, most people just draw using the points as diameter indication.

Thanks for setting me straight

A 44.1kHz sample rate can fully capture all of the frequencies in 20kHz+ audio signal.

OK - what about the 24 bit part?

amun,

In terms of rendering (playing into a room or headphone), controlled experiments have not been able to demonstrate any advantage for rendering more than 16 bits to a human listening panel.

I don't want to extrapolate this too far, but consider an interest calculation for a savings account. When the account is ultimately settled, the resolution of that payment is limited to the currency or coin available. One cannot pay fractions of a coin. And, what is the point of chopping a coin into a fraction? Would one need to purchase a fraction of a stick of gum? However, while calculating along the way, it is handy to use many decimal places in order to minimize errors caused by little truncations.

24 or 32 bits are very handy in the recording studio because they minimize issues caused by processing truncation, but we only need 16 bits for rendering. A prime benefit of recording at 24 bits is that the recording engineer does not need to "ride gain" (keep adjusting the recording level to match the artists). In order to minimize the impact of noise, one attempts to keep the levels high, but if the input signal level crosses over the maximum allowed, there will be clearly audible flaws in the recording. Recording at 24 bits relaxes this traditionally difficult aspect of recording.

When we "pay" our audio signal, we only need 16 bits.

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If the end user wants to continue processing the recording, having access to the 24 bit data would be useful. But this is not the realm of the audiophile. It is interesting to note that I have never seen this mentioned in any of the heated discussions about 16 vs 24. All of the "heat" is directed toward somehow delivering the full 24 bits to the speakers -- without any processing.

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BTW, while I can be a nightmare critic, picking up little clicks, pops, noises (in a local hall one really should close the men's room during a recording), and distortions, I'm not against constructive processing. For example, in a noisy listening situation a little dynamic range compression works wonders for listening enjoyment. And, the room could have an ugly frequency response issue that could be improved with a little equalization.

OK - what about the 24 bit part?

"Resolution" is a very misunderstood largely because of the pictures of jagged sine waves or analogies with photography and imaging that are so often used to explain it. These, usually, foster incorrect conclusions about how digital audio works.

When you increase "resolution", you are really just lowering the noise floor. An 8-bit sample will sound horrible because there is a lot of sampling noise. A 16-bit sample will sound better because there is less noise: the noise floor is lower.

Increasing the sample rate from 16 to 24 bits lowers the noise floor even further. However, a 16-bit sample rate is already capable of reproducing audio down to around -120dB, which is, for all practical purposes, beyond the ability of human hearing.

And, even in the quietest environment practical (like a commercial recording studio) the background noise will mask the quietest sounds, making the range of human hearing 100dB or less in practise. Even the most carefully mastered commercial audio material has a dynamic range less than 60dB which is well within the range of 16-bit audio.

As buzz mentions, 24-bit is useful during the music production stages where you may be mixing and manipulating dozens of tracks and applying processing (reverb, compression, etc.), but once the final product is completed, 16-bits is enough.

This is all explained, very well, in the Xiph article.

Have you actually read and understood it?

For reference, a lot of this stuff is also explained, to a much higher degree of detail and complexity in articles and books by Audio Engineers. One of the more famous ones is "Mastering Audio" by Bob Katz (ISBN: 0240 808376) who, by the way, is another expert in digital audio who should be taken notice of.

Cheers,

Keith