Lossless audio — the better-than-MP3 alternative you should know

We’ve been hearing a lot about lossless audio lately. Apple Music says it has it. So does Amazon Music. Tidal and Qobuz have it too, but Spotify doesn’t. (Yet. Or still.)

Is lossless audio a big deal? Or just marketing hype? Why does it feel like a few years ago no one was talking about it, and now almost everyone is. Does it really affect sound quality? And should you consider ditching your streaming service if it doesn’t have lossless audio?

All excellent questions, and we’ve got the answers. Let’s get into it.

What is lossless audio?

Digital audio — the kind that’s written onto audio CDs — takes up a lot of room. Eighty minutes of stereo sound needs 700MB of storage space. Making a song smaller can save a lot of money in terms of storage and bandwidth. There are two ways to do that: lossy compression and lossless compression.

As the names suggest, lossy compression removes some of the original information — some audio is lost — in the process of creating a smaller file. Lossless, by contrast, achieves a smaller file size but retains 100% of the original audio data. So when we talk about “lossless” audio, we’re referring to audio that has been compressed losslessly.

What does compression sound like?

Here’s a fun fact: We don’t listen to compressed audio at all — at least not directly. Before your favorite streaming app can play a song, it must be decompressed. Because a losslessly compressed song is exactly like its original source, there’s no perceptible difference between listening to track from a CD versus a track that has been losslessly compressed and then decompressed. Thanks to this fidelity, lossless is sometimes described as “bit-perfect.”

A track that has been lossy compressed, however, no longer has all of the original data, and there’s no way to get it back when you decompress it. There are varying degrees of lossy compression. At the lowest level, lossy audio sounds pretty bad. If you’ve ever been on a phone call and the other person has sounded distorted and wobbly — that’s usually because of lossy compression.

At its highest level, however, it can sound so close to CD quality that most people can’t tell the difference. But some folks can (or say they can), which is why music streaming services are increasingly advertising that they offer lossless audio.

Why use lossy compression at all?

If lossy compression destroys some of the original audio data, why use it? While some of the original sound is removed, many people don’t notice it at all (more on why in a moment) and the up-side to that compromise is that lossy compression can create incredibly small files. While today most of us have fast broadband connections and plenty of storage room on our phones and computers, in the late 1990s, when digital music arrived, it was a different story. Back then, at the dawn of music sharing across the internet, 28.8 kbps dial-up connections were the norm, and mobile data connections were effectively nonexistent.

If you had tried to download a three-minute song as an uncompressed CD audio file, it would have taken two hours and 18 minutes. (And that’s assuming Mom didn’t pick up the phone in the middle of it.) Even a losslessly compressed version would have taken around 80 minutes.

What’s an example of a lossy audio format?

The MP3 format is the poster child for lossy audio. It became ubiquitous in the late 1990s and early 2000s thanks its small size. Depending on the bitrate used, a song encoded as an MP3 can be as small as one-tenth the size of the same song encoded as an uncompressed file on a CD. Or put another way, they could be transferred in as little as 15 minutes.

Once portable music players like the Apple iPod began to show up and file-sharing services like Napster became popular, the MP3 became synonymous with digital music. Other lossy formats include AAC and Ogg Vorbis.

MP3s use a type of lossy compression that’s based on the science of psychoacoustics, which identifies the information our brains rely on to recognize a song and thus which information can be safely removed.

If it helps, you can think of it like a JPG image. If you look very closely at the edges of objects in a JPG, you may see a bit of blockiness or blurriness, but it’s still an easily recognized photo. Like MP3s, JPGs remove a bit of image information for the sake of a smaller file. It’s a very effective technique.

Unfortunately, many MP3s don’t sound much better than FM radio, and even the best MP3s are considered by some to be inferior to uncompressed CD audio — widely thought of as the gold standard for digital audio.

While connection speeds and storage remained a bottleneck, the MP3 continued its reign. But more recently we’ve seen big gains in both areas, which pushed a renewed interest in lossless compression. Losslessly compressed files are still smaller than their uncompressed counterparts (as little as half the size), but they achieve their space savings through algorithmic optimization of data. Nothing is removed — it’s simply squeezed into a smaller space and then returned to its original size when it’s time to play the file.

The most popular lossless format is the open-source FLAC, but other lossless formats exist, too, like Apple’s ALAC and to a much lesser extent WavPack and Monkey’s Audio.

If you’ve ever zipped a folder or a file on your computer to make it small enough to email, you’ve already experienced the benefits of lossless compression.

What about hi-res audio?

Despite being more than 42 years old, CD audio remains the most popular form of uncompressed recorded digital audio. To some, it’s still the gold standard. For others, newer technology promises even greater levels of fidelity. Any audio that surpasses the amount of information captured by CD audio is known as hi-res audio.

You can read all about hi-res audio in our in-depth explainer. For our purposes, the most important thing is that whether you want to listen to CD audio or hi-res audio without popping a physical disc into a player, or saving humungous files to your computer, you need lossless compression.

Lossless formats like FLAC or ALAC can compress any digital audio, including hi-res recordings.

Where can you get lossless audio?

In the early days of lossless compression, the most popular sources were CDs. Using software, people would rip their CDs to FLAC files, much the same way they had once done with MP3s.

And, just like with MP3s, people would use legally dubious file-sharing apps to swap their FLACs.

But legitimate lossless download stores began to appear — like HDtracks, which offered CD quality, and hi-res quality lossless tracks in FLAC format. Strangely, Apple’s iTunes Store — easily the most popular source for online music purchases — has never offered lossless downloads in either FLAC or ALAC.

More recently, since the advent of broadband speeds both at home and on mobile devices, streaming music services have embraced lossless formats. Apple Music, Amazon Music, Tidal, Qobuz, and Deezer have all added CD-quality lossless tracks to their libraries. In some cases, lossless is now the default, with lossy versions acting as secondary streams for when bandwidth is limited or (in the case of mobile data) too expensive to support lossless streaming. A portion of these libraries are also available in hi-res audio.

It’s worth noting that currently, Spotify does not offer any tracks in lossless audio, though we remain hopeful that this will eventually change.

Depending on your streaming service, you may have to enable lossless audio in the settings. Look for the option to change audio quality for three different scenarios depending on the app: Wi-Fi streaming, mobile streaming, and downloads. Some apps may not refer to lossless audio — Amazon Music, for instance, uses the terms HD and Ultra HD to refer to CD quality lossless and hi-res lossless, respectively.

What do you need to hear lossless audio?

Having a source of lossless audio is the starting point. But depending on the device you are using, you may not actually hear the extra detail that lossless audio can give you.

Here’s an example: An Apple Music subscription will let you stream lossless audio to the Apple Music app on your iPhone. The app can decompress that stream into CD quality or hi-res quality (if the song in question is a hi-res track) digital audio.

But if you’re using a set of wireless headphones or earbuds, you won’t hear CD or hi-res quality.

This is because the iPhone has to once again compress that audio to make it small enough to stream using Bluetooth, which is a relatively low-bandwidth connection. To do that, it uses AAC — one of the lossy compression formats we discussed earlier. The iPhone is very good at AAC, so there’s a chance you won’t notice, but it’s no longer lossless once it gets to your ears.

There are other Bluetooth codecs like aptX and LDAC, which (if you have a phone and wireless audio device that both support one or more of these codecs) can preserve more information than AAC, but they’re still considered lossy.

At the moment, only one Bluetooth codec is lossless: aptX Lossless. However, it’s only supported on a few smartphones equipped with Qualcomm’s Snapdragon Sound platform, and it only works if the wireless earbuds/headphones are also aptX Lossless compatible. Even then, aptX Lossless only promises bit-perfect transmission of CD quality — not hi-res — audio.

A (mostly) wired world

Until we get a version of Bluetooth that can handle more data, listening to true lossless music from a smartphone requires a digital-to-analog converter (DAC) and a wired set of earbuds or headphones. Phones that still have built-in headphone jacks all have built-in DACs. Some are better than others, so you may need to do some research especially if you want to listen to hi-res lossless (not all DACs are hi-res compatible).

Alternatively, you can use an external DAC/amp. These plug into your phone’s USB-C or Lightning port and have their own headphone jack.

Some external DAC/amps cost hundreds of dollars and possess special features like DSD and MQA compatibility, high-power amps, and separate volume control, or they may use circuitry aimed at achieving exceptionally low levels of distortion. Others, like Apple’s simple Lightning-to-3.5mm adapter, cost just $9, but are limited in their features.

The resampling gotcha

Ok, so you have a source of lossless audio and a DAC that translate the decoded lossless audio into something you can hear. All done, right?

Well, yes, but audio purists will want to take note of a somewhat frustrating thing that can happen between these steps, known as resampling. Some app/device combinations create a condition where the DAC, instead of cleanly converting your lossless digital audio into analog, first resamples the digital audio. Resampling is when the sampling frequency of the audio (let’s say 44.1kHz, for example) doesn’t match the sample rate your DAC is set to (say, 48kHz). When this happens, the DAC converts the 44.1kHz signal to 48kHz, a process that can’t be done without some alterations to the original audio. With most high-quality DACs, this will likely be invisible to your ear, but it’s technically no longer lossless.

The Headphone Show has a great video on YouTube that explains the problem in greater detail and the steps you can take (in some cases) to correct for resampling.

Lossless at home

Hearing lossless audio at home can be a lot easier if you own Wi-Fi-capable wireless speakers, or if you use a device like an Apple TV. These devices can receive and decompress lossless audio straight from a subscription service like Amazon Music. Once decompressed, they can play those streams through their own built-in DACs.

Alternatively, if your audio component is compatible with Apple AirPlay or Google Cast, these Wi-Fi-based protocols support the streaming of lossless audio from your phone or computer.

The future is lossless

Today, our media ecosystem is comprised of both lossy and lossless audio, but the trend is clearly toward lossless. Our connection speeds (especially mobile speeds thanks to 5G) get faster every year, and storage prices have been steadily decreasing for decades.

In the not-too-distant future, there will be virtually no reason to use lossy compression.

At least, not for audio. It may take considerably longer for lossless video to become the norm.