Have you ever noticed the music on Vevo sounds better when played from a CD?

When Tidal relaunched last under Jay Z and several pop artists' ownership, it didn't just kick up a storm of controversy for Spotify in regards to the amount of royalties it pays to artists and rights holders; it increased awareness about the quality of audio files being offered by streaming services.

Here's what Tidal wanted the world to learn: it offers "CD-quality audio", also known as high-fidelity sound, which is music files that haven't been compressed, while most other streaming services, including Spotify and Vevo and YouTube, deliver significantly compressed audio/music files with a steep cut in quality.

While all that sounds quite interesting, you're probably now wondering what is the difference between high-res and high-fidelity sound. You're likely also wondering about the quality of music you stream and whether it's considered bad.

Well, Pocket-lint has gathered up everything you need to know and more, with the purpose of helping you decide which streaming services offer great sound and actually deserve your hard-earned money.

READ: Tidal explained: What is it?

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Before we get into high-res audio, let's start by discussing compression.

It's no secret that music industry went from physical formats (like vinyls) to digital formats (like MP3s), but most people don't realise sound quality was impacted during that transition due to a demand to make music files smaller. Simply put: they're easier (and cheaper) to distribute to consumers who download or stream.

In order to make a music file smaller, it must go through either lossless or lossy compression. With lossless compression, all original data from the music file can be restored after it is uncompressed, where as lossy compression permanently reduces the music file by cutting out some data during the encoding process.

Whenever any data is lost or removed from a music file during compression, the resolution is negatively impacted. If you want to hear the difference between lossless and lossy, check out Tidal's excellent demonstration here.

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There's no universal standard for high-resolution audio, which is also called high-res audio or HRA, though The Digital Entertainment Group (in conjunction with the Consumer Electronics Association and The Recording Academy) has published the following formal definition for the term:

  • High-res audio is: "Lossless audio that is capable of reproducing the full range of sound from recordings that have been mastered from better than CD quality music sources."

Now, when music is digitised for downloading and streaming purposes, it is basically broken down into a series of audio snapshots (sort of like how several still frames make up a film), and our brains interpret all these snapshots together as continuous sound. The more snapshots taken, the more detail a digital music file will have.

We won't get too scientific - but just know that sampling rate is the number of snapshots taken per second when analogue sound waves are converted into digital. There's another aspect called bit depth. It's the amplitude of the waveform at each sample point (8-bit has 256 levels for each sample; 16-bit has up to 65,536 levels).

So, to recap: high-res audio refers to audio files that have a higher sampling rate and more bit depth than a CD (and it is is generally best to have the highest combination possible). A CD has a sampling rate of 44.1kHz and a bit depth of 16-bit, while high-res files have a sampling rate typically ranging between 96kHz and 192kHz at 16- or 24-bit.

Now, let's talk about bitrate. It refer to the number of bits - or the amount of data - that is processed over a certain amount of time. So, in audio, it means kilobits per second. An iTunes song has 256 kilobits of data stored in every second of a tune. Like sampling rates and bit depths, it's better to have a higher bitrate.

But if you download a high-res file with a high bitrate, it'll naturally take up more space on your computer.

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There are several high-resolution audio file formats available with incredible sampling rates and bit-depths. Two of the most popular types are FLAC (Free Lossless Audio Codec) and ALAC (Apple Lossless Audio Codec), both of which are compressed but claim to hold onto and recover every single bit of data from a file.

Tidal offers something called "high-fidelity sound", which it described as "music files that have not been compressed down". That's not entirely true. Tidal streams FLAC audio files. They're compressed, as we mentioned earlier, and designed for efficient packing of audio data so that (in theory) no information is lost.

FLAC files on average have a sampling rate of 44.1 KHz, a bit depth of 16-bit, and a bitrate of 1411Kbps. CDs also have a bitrate of 1411kbps, while "lesser-quality" MP3s have a bitrate of 320kbps. (For reference: the chart above compares file format bitrates offered by Tidal, Spotify, and iTunes.)

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Tidal, of course, is one streaming service that offers high-fidelity audio for £19.99 per month. It has a catalogue of 25 million tracks and streams at 1411kbps. Tidal works with up to 35 platforms as well, including Android and iOS. It's also partnered with 16 hardware brands to ensure fans everywhere get the best listening experience.

Qobuz is both a music streaming service and download store. It offers high-res audio music streams in 16-bit/44.1kHz FLAC. The hi-res tier costs £19.99 per month, and you can listen to your music through the Qobuz apps for iOS and Android devices. It's also integrated with Sonos, Samsung, and Astell & Kern hardware.

Here's a list of other streaming services and download stores that offer high-res audio files: HDTracks, Naim Label, Linn Records, Bowers & Wilkins Society of Sound, PonoMusic, 2L, 7Digital, Gimell, and HD Klassik.

Pocket-lint's Audio hub has more information about high-res audio, high-res players, and streaming services.