HOW IT WORKS
Lossless audio on Apple Music
Music was compressed using digital file formats, but streaming services are now able to use lossless audio formats
YOU WILL LEARN How audio compression works, and how to get the best quality from Apple
Well, it’s about time. After years of rumours, Apple has finally taken the plunge and added lossless and highresolution audio to its Apple Music streaming service. It’s bizarre, really, that a company that talks so much about innovation has taken so long to catch up with the latest audio technologies. In fact, with the exception of Spotify, all the main music streaming services have been offering lossless or high-res audio for years (which is why many of us opt for a subscription to Tidal rather than Apple Music).
But what, exactly is lossless or high-res audio? That question takes us back to the very first digital audio format – ye olde Compact Disc – way back in the 1980s. The music stored on CDs is ‘digitised’ – converted from analogue sound waves by ‘sampling’ the original sound and then storing it as digital data. Music stored on CD is sampled at a rate of 44,100 times per second – also known as 44.1kHz. Each sample also requires a certain number of ‘bits’ to be stored as a digital file. So, for CD-quality music, the sampling rate is 44.1kHz and the bit-rate is 16-bits – with this format often referred to as 16-bit/44.1kHz.
Lossy vs lossless
Recording 44,100 samples a second means you can end up with some really big audio files and, until relatively recently, home broadband services simply weren’t fast enough to stream true CD-quality music. So, to make the file sizes a bit more manageable, the music was ‘compressed’ using digital file formats, such as the old MP3 or Apple’s AAC, that discard some of the audio data and sacrifice some of the detail and quality of the original recording in order to reduce the size of the audio file. This is known as ‘lossy’ compression, as some of the audio data is lost in the process of compressing the file.
But, of course, modern broadband services are much faster, so the size of digital music files isn’t really a problem anymore. As a result, streaming services are now able to use lossless audio formats that preserve all of the original audio data with no loss of detail or sound quality at all. The lossless WAV and FLAC formats are widely used online, while Apple Music uses the Apple Lossless Audio Codec, (or ALAC). So, the term ‘lossless audio’ generally means music that is equivalent to true CD-quality recorded in 16-bit/44.1kHz format.
In addition to CD-quality lossless audio, Apple Music – and streaming rivals such as Qobuz and Tidal – also offer
‘high-res audio’ as well. This extra level of quality is often compared to the ‘studio master’ recordings that are created by artists in a professional recording studio. These high-res recordings can have sampling rates as high as 192kHz, and bit rates of 24-bit or even 32-bit. By default, Apple Music still streams music in the lossy AAC format, but if you look at the Settings panel for the Music app on your Mac or iOS devices, you’ll now find an option to switch into the new Lossless Audio mode as well.
The standard Lossless Audio mode streams CD-quality music in 16-bit/44.1kHz format, although some tracks may also offer a slightly higher quality option that uses 24-bit/48kHz. There are currently 20 million lossless tracks available on Apple Music, with Apple aiming to get the entire library of 75 million tracks upgraded to lossless by the end of this year. However, the real high-res audio option – which Apple refers to as Hi-Res Lossless – goes right up to 24-bit/192kHz. The bad news for audiophiles is that Hi-Res Lossless requires you to buy some additional hardware, known as a DAC – digital-toanalogue converter – because the cheapand-cheerful sound chips that Apple uses in Macs and mobile devices simply can’t handle that level of audio quality on their own. And, bizarrely, for Apple audiophiles, there’s one other hardware problem that we have to deal with as well…
Bluetooth blues
Millions of people now use Apple’s AirPods or Bluetooth headphones from other manufacturers for listening to music. The convenience of Bluetooth wireless headphones is great, of course – but it comes at a price. Bluetooth streaming uses its own form of lossy compression, so even if you’re streaming lossless or high-res audio from Apple Music or any other streaming service, your Bluetooth headphones are actually compressing it all over again and serving you lower quality lossy audio instead.
Apple has really shot itself in the foot here, as its own headphones can’t play the highest quality music that is now available on Apple Music. If you really want to hear music with the best possible sound quality then good oldfashioned wired headphones are still your best bet. The HomePod and HomePod mini can’t play lossless or high-res audio at the moment either, although Apple is working on a software update that will hopefully solve this problem. It’ll probably take a few months for all the technical details to be ironed out, but the fact that Apple has finally adopted high-res audio – and, crucially, doesn’t charge any extra for it – means that lossless audio is the new industry standard for streaming services. Cliff Joseph