Youtube High Resolution Audio
Tommasa Gaetz
High-resolution audio is generally used to refer to music files that have a higher sampling frequency and/or bit depth than that of Compact Disc Digital Audio (CD-DA), which operates at 44.1 kHz/16-bit.[2]
One of the first attempts to market high-resolution audio was High Definition Compatible Digital in 1995, an encoding/decoding technique using standard CD audio.[6] This was followed by two more optical disc formats claiming sonic superiority over CD-DA: SACD in 1999, and DVD-Audio in 2000. These formats offer additional benefits such as multi-channel surround sound. Following a format war, none of these achieved widespread adoption.[7]
Further attempts to market high-resolution audio on optical disc followed with Pure Audio Blu-ray in 2009, and High Fidelity Pure Audio in 2013.[9] Competition in online high-resolution audio retail stepped-up in 2014 with the announcement of Neil Young's Pono service.[10]
In 2014, the Japan Electronics and Information Technology Industries Association (JEITA) announced a specification and accompanying "Hi-Res AUDIO" logo for consumer audio products, administered by the Japan Audio Society (JAS). The standard sets minimums of 96 kHz sample rate and 24-bit depth, and for analog processes, 40 kHz.[4] The related "Hi-Res Audio Wireless" standard additionally requires support for the LDAC, LHDC, LC3plus and MQair codecs.[4] Sony reaffirmed its commitment towards the development in the high-resolution audio segment by offering a slew of Hi-Res Audio products.[11][failed verification]
Business magazine Bloomberg Businessweek suggests that caution is in order with regard to high-resolution audio: "There is reason to be wary, given consumer electronics companies' history of pushing advancements whose main virtue is to require everyone to buy new gadgets."[16]
Most early papers using blind listening tests concluded that differences are not audible by the sample of listeners taking the test.[18] Blind tests have shown that musicians and composers are unable to distinguish higher resolutions from 16-bit audio at 48 kHz.[19] One 2014 paper showed that dithering using outdated methods[a] produces audible artifacts in blind listening tests.[20]
Joshua Reiss performed a meta-analysis on 20 of published tests, saying that trained listeners could distinguish between hi-resolution recordings and their CD equivalents under blind conditions.[21] Hiroshi Nittono pointed out that the results in Reiss's paper showed that the ability to distinguish hi resolution audio from CD quality audio "was only slightly better than chance".[22] However for perspective, the same is true of blind tests between lossy compression (mp3 or equivalent) and lossless CD quality audio, which are widely accepted as audibly different but dependent upon the playback equipment and listening skill (training) of the participants.[23]
Some technical explanations for sonic superiority cite the improved time domain impulse response of the anti-aliasing filter allowed by higher sample rates. This reduces the energy spread in time from transient signals such as plucking a string or striking a cymbal. [24][25]
After years of niche positioning in the music world, high-resolution audio (or 'hi-res audio') finally hit the mainstream thanks to a huge raft of support from streaming services (such as Apple Music, Tidal and Amazon Music) and products (from smartphones to pretty much every digital hi-fi component) alike.
But should you care about hi-res audio? If you want the best digital music experience possible or at least better sound quality than you're currently used to (and why wouldn't you?), then yes; hi-res audio is definitely worth investigating.
It can be a daunting prospect. After all, what exactly constitutes hi-res audio? How does it differ from 'lossless' audio? What do all the different file formats and numbers mean, and what do you need to play it?
That's where we come in. Our handy guide will take you through the ins and outs of hi-res audio. By the end, we hope you'll know everything you need to know (and then some) and will be well on your way to enjoying your new and improved music-listening lifestyle.
In its simplest terms, hi-res audio tends to refer to music files that have a higher bit depth and/or sampling frequency than CD, which is specified at 16-bit/44.1kHz. This definition of 'CD quality' is now commonly referred to as 'lossless', too.
Sampling frequency (or sample rate) refers to the number of times samples of the signal are taken per second during the analogue-to-digital conversion process. The more bits there are, the more accurately the signal can be measured in the first instance, so going from 16-bit to 24-bit can deliver a noticeable leap in quality. Hi-res audio files usually use a sampling frequency of 48kHz, 96kHz or 192kHz at 24-bit, but you can also have 88.2kHz and 176.4kHz files.
Hi-res audio does come with a downside, though: file size. A hi-res file can typically be tens of megabytes in size, and a few tracks can quickly eat up the storage on your device. They can be cumbersome to stream over your wi-fi or mobile network, though internet bandwidth has generally improved in recent years and this is less of an issue nowadays. These larger file sizes have, however, been why Bluetooth hasn't been able to pass through hi-res audio losslessly (i.e. without lossy compression) yet.
Thankfully, storage is much cheaper than it used to be, so it's easier to get higher-capacity devices. Streaming technologies like MQA (see below) cleverly found a way to make packaging and streaming hi-res audio more efficient, though again streaming hi-res audio is less of an issue nowadays.
They include the popular FLAC (Free Lossless Audio Codec) and ALAC (Apple Lossless Audio Codec) formats, both of which are compressed but in a way that means that, in theory, no information is lost. They are 'lossless' as opposed to 'lossy'. Other formats include the uncompressed WAV and AIFF formats, DSD (the format used for Super Audio CDs), and the more recent MQA (Master Quality Authenticated).
MP3 (not hi-res): Popular, lossy compressed format ensures small file size, but far from the best sound quality. Convenient for storing music on smartphones and iPods, but doesn't support hi-res.
WAV (hi-res): The standard format all CDs are encoded in. Great sound quality but it's uncompressed, meaning huge file sizes (especially for hi-res files). It has poor metadata support (that is, album artwork, artist and song title information).
FLAC (hi-res): This lossless compression format supports hi-res sample rates, takes up about half the space of WAV, and stores metadata. It's royalty-free and widely supported (though not by Apple) and is considered the preferred format for downloading and storing hi-res albums.
MQA (hi-res): A lossless compression format that efficiently packages hi-res files with a high emphasis on retaining quality. Used for Tidal Masters hi-res streams, with increasingly high product support in the digital hi-fi domain. MQA Ltd was recently acquired by Canadian firm Lenbrook, who also owns Bluesound and NAD.
Downloads from sites such as Amazon, as well as the Spotify streaming service, use compressed file formats with relatively low bitrates. For example, Spotify (which unlike Amazon Music and Apple Music has still not delivered its promise of CD-quality streams, via Spotify Hi-Fi) uses 320kbps Ogg Vorbis streams.
The hi-res 24-bit/96kHz or 24-bit/192kHz files should, therefore, more closely replicate the sound quality the musicians and engineers were working with in the studio. And they could be that very same recorded file, too. These files are labelled as "Studio Masters" in some cases.
There's a huge variety of products that can play hi-res audio these days. It's never been easier to get involved, now that the digital and streaming audio ecosystem almost universally supports hi-res, including popular streaming platforms such as Sonos and Google Chromecast (although not AirPlay 2, which currently has a limit of 16-bit/44.1kHz). Apple products are increasingly hi-res compatible following the addition of a hi-res library to Apple Music, too.
These days, you don't even have to completely abandon your vinyl collection to go hi-res, either; turntables such as the Sony PS-HX500 let you digitise your vinyl collection by ripping your record tracks into hi-res audio files.
Hi-res audio can be streamed wirelessly between phones and headphones/speakers that support the latest Bluetooth codecs (such as aptX HD, aptX Adaptive and LDAC)... but not losslessly (i.e. not without compression). Qualcomm claims to have found a way to transmit CD-quality music losslessly with its upcoming Snapdragon Sound aptX Lossless solution, and MQA's SCL6 could also pave the way for better on-the-go quality, but it could be some time before portable hi-res playback over non-wi-fi means materialises.
Desktop
For a desktop solution, your laptop (Windows, Mac, Linux) is a prime source for storing and playing hi-res music. After all, this is where you would download hi-res files from hi-res download sites if you did want to own your music. But make sure the software you use to play music also supports hi-res playback. Apple Music, for instance, doesn't support it, even if your MacBook does, so you'll need to download separate music-playing software. The likes of Channel D's Pure Music and Amarra are worth considering for a Mac. On a PC? Try JRiver Media Center. Roon is an increasingly popular (paid-for) music management platform worth considering if you listen to music from several sources and on various (Roon-compatible) kit.
DACs
We wouldn't just rely on your computer or phone's internal DAC to do hi-res audio justice, either. A USB or desktop DAC (such as the Chord Mojo 2, Cambridge Audio DacMagic 200M and AudioQuest DragonFly Cobalt) is a good way to get great sound quality out of hi-res files stored on, or streamed from, your computer or smartphone, whose own audio circuits don't tend to be optimised for sound quality. Simply plug a decent digital-to-analogue converter (DAC) in between your source and wired headphones for an instant sonic boost.