What is Hi-res audio? A Sony Music engineer explains
Hi-Res Audio, it’s something we’re more than familiar with here at Sony Mobile. First seen on our Z3 handset way back in 2014 and a regular feature of flagship handsets since. In early January the tech received a boost as Sony Music, Universal, Warner, the Recording Publishing Association of America, and Pandora all announced their support for Hi-Res Audio streaming.
You may have also seen Sony recently worked with Google to make sure Android O will sound way better. Well we care about sound here at Sony HQ and you’ll find Hi-res audio capability in many of our devices including the XZ and XZ Premium. To discover what makes hi-res audio hi-res we stopped by London’s award-winning Metropolis Studios (studio of choice for Adele, U2, Bjork and Madonna, to name a few) to catch-up with Peter Hewitt-Dutton, one of their leading Mastering Engineers to discuss Hi-Res, Low-Res and everything in-between.
Peter, lovely to meet you. What do you do here and how long have you been with Metropolis?
I joined Metropolis by sitting on the night reception and almost 10 years later I’m now a Mastering Engineer, which means I take previously mixed audio files and prepare them for final distribution.
To be as brief as possible, what exactly is Hi-Res Audio?
Without getting too technical, Hi-Res is a general term for digital audio being reproduced at sample rates and bit depths higher than that of a normal CD or for those numbers guys out there, 44kHz, 16 bit.
How does the recording process differ between Hi-Res and its standard counterpart?
Virtually all music is recorded in a high-resolution form, but the standard CD, and download versions such as MP3s are heavily reduced, and are therefore compromised versions of the initial high-resolution master. It’s really the mastering and output where the improved clarity comes.
Ok, this time with that technical head-on – what is the difference between standard and Hi-Res audio?
The range of frequencies able to be reproduced, and the level of detail in the sound dynamics.
To give you an example – as the sample rate increases, the highest frequency the system is able to record also increases. And although the human ear is not capable of hearing much above 20kHz, we are able to detect the harmonies and transients in frequencies far higher. These are particularly important in music to maintain the feel of the piece.
Then moving on to “bit depth”, this will determine the dynamic range of the system, that is the difference between the loudest and quietest sounds it can accurately store. CD sits at about 16bit, but all Hi-Res content is 24bit. This means more of the nuance of the performance is captured, as well as the full range of the analogue equipment used to record material. It’s a sharper sound that truly reflects the musician’s work.
So what does that mean in reality for the average music fan?
It means they are able to have the music a lot closer to what the artist actually heard in the studio and mastering room when they signed the record off. In many cases it will be the exact audio they approved. Sample rate converters are then used for the lower resolution formats, to get it to CD and standard digital formats, which means they lose quality on the way.. With Hi-Res, everything the artist wanted to be heard is preserved, and delivered to the listener.
So what about “low-res” files, will Hi-Res audio products improve the listening of these?
Yes. The digital-to-analogue converters needed to convert high resolution files need to be of a higher quality than their low-res counterparts. So those low-res files will be produced closer to their full potential than on lesser equipment.
Do any particular genres benefit from this greater fidelity?
If you simply remove the process of “down sampling” any audio will sound better. It’s one particularly destructive process. That said the more dynamic the material, the more noticeable the difference will be. It also comes down to how well recorded the material is; by which I mean music that takes advantage of the full frequency range available, is well mixed to give all the instruments the space they need, but also maintaining the subtle acoustic information. It is very easy for a lot of this to be lost in a poor mix or master.
TV has graduated from HD to 4K…is Hi-Res as good as it gets for audio?
Not at all – The record industry is making incredible leaps in tech and analogue is having something of a revival. As better products and converters are made available, analogue tape can be recaptured as new digital formats resulting in a better sound. We’re not done yet.
Do you need any special equipment to make the most of Hi-Res audio e.g. Top of the range headphones?
To take full advantage, yes. But the differences will be noticeable to a lot of people down to mid-range equipment. It is only really the cheapest converters, amps and speakers, which will not benefit. The sound you hear is only as good as the weakest point in the chain. A Hi-Res file will simply make the best use of the equipment you have, sounding as good as it can.
Before you get back to it, do you have any recommended tracks that are good to show off the power of Hi-Res audio?
I was lucky enough to work alongside John Davis on the recent Led Zeppelin remastering process. That was all captured at “96/24”, meaning there was virtually no limiting at all. It sounds just fantastic.
To discover more about Hi-Res audio follow this link.