How do I get the best audio quality from streaming music services?

When it came to how people listened to music at home, vinyl ruled until the 1970s. But technology does not stand still. Cassettes, which had worse sound quality but were more convenient, gave records a run for their money. In the ’80s, CDs took over the market with their superior audio quality and sturdiness, and things stabilized once again for a few decades.

Then MP3s appeared and Internet downloads eroded the CD’s hegemony—again, convenience won out over quality. Once consumers’ Internet connections were fast enough, streaming became the norm, and since 2017 more people are getting their music from streaming services than from any other source; Last year, streaming accounted for 84% of recorded music sales.

But we all have noticed that there are differences among streaming services in terms of sound quality. Some of them are excellent, and some leave a lot to be desired. Many companies offer “tiered” services, which give you better audio fidelity in exchange for a higher monthly fee.

What is compression?

Streaming services—and also downloading services—use what is known as “compressed audio”. This is not the same type of compression used in a recording studio to limit the dynamic range of a track, such as on vocals or a drum set. It is a form of data compression, and can be “lossless” or “lossy”.

Lossless compression is similar to using a .ZIP archive, in that when you uncompress the file, what comes out is an exact copy of what went in—thus achieving full fidelity (“CD quality”). is maintained. Lossy compression is like the compression you use when you convert a RAW or TIFF image to a jpeg: some data is permanently removed from the original file.

An algorithm or “codec” (for compressor/decompressor) determines what data can be removed from an audio file to reduce its size. How does the lossy codec determine which data is removable?

Lossy compression algorithms are very complex, and take into account factors such as dynamics (louder signals require more data), stereo separation (sounds that are in the center of the stereo image only need to be transmitted once). is), and psychological masking, a phenomenon simply put, meaning that if two sounds of unequal loudness come together, the softer sound will not be heard.

The aggressiveness of the codec, and thus the amount of data that gets away, is expressed as a data rate or bit rate, and is one of the major factors to consider when choosing a streaming service. It is to be distinguished from the sampling rate, which is the number of times per second the original waveform is measured by the analog-to-digital converter at the front of the recording chain.

understanding formats

Data rates range from 32 kbps (32,000 bits per second) to 1,411 kbps – if you see a higher number, it means there is no compression. The low data rates are fine for podcasts and other types of speech, and are useful in situations where the Internet connection is slow, such as when you’re on your phone with a weak signal but poor quality music.

Compromise in quality can be heard as poor stereo imaging and less separation between left and right channels, high frequencies as lack of “air” is filtered out, loss of sense of presence as transient – drums Sound starters are soft, low-level noises and a common “dirt” for sound.

The other major factor is the type of codec the streamer is using. MP3 (originally MPEG-1 Audio Layer 3) is the most famous of the lossy codecs, and was the first to find widespread use. The MP3 codec is private property: it was developed in 1994 and is still owned by the German research firm Fraunhofer-Gesellschaft, and any service that generates content using the codec is supposed to pay royalties to Fraunhofer.

AAC, or Advanced Audio Coding, appeared a few years later as part of the MPEG-4 compression algorithm. It was adopted by Apple, which immediately used it on the popular iTunes platform. AAC is more efficient than MP3, meaning that with AAC the sound quality at a given bit rate is better, and content providers are not required to pay royalties for using it.

In addition to these two major formats, there are two more lossy compression codecs used by streaming services, which are both free and open source, and offer higher efficiency than MP3: OGG Vorbis, which is used by many video games and Wikipedia Done through; and Opus, used by Vimeo. As far as lossless codecs go, the most well known are FLAC (for free lossless audio codec) and ALAC (Apple Lossless Audio Codec), which Apple now uses for all of its streams. There is also a lossless version of Windows Media.

Not all streaming services are created equal

Some services like Tidal offer super high-resolution lossless audio streaming with data rates as high as 9,216Kbps, which can enhance the experience if you want to listen to multichannel or spatial audio formats like Dolby Atmos or Sony 360 Reality Audio. . For general stereo listening, however, it is highly debatable whether the extra data adds anything to the audio quality.

Here are the bit rates and codecs of some popular streaming services:

• Amazon Music: 256Kbps AAC, Unlimited Tier FLAC
• Apple Music: ALAC
• Bandcamp: 128Kbps MP3 (but downloads are lossless)
• Deezer: 128 and 320Kbps MP3, FLAC
• Pandora: Free tier is 64Kbps AAC, paid tier is 192Kbps AAC
• Cubase: FLAC
• SoundCloud: 128Kbps MP3, High quality is 256Kbps AAC
• Spotify: Free tier is 128 kbps OGG Vorbis, paid tier is 320 kpbs MP3 and OGG Vorbis, and a lossless tier is reportedly in the works
• Tidal: Free service is 160Kbps AAC, paid level is lossless.
• YouTube Music: 256Kbps AAC

So if you’re looking for the highest quality possible in a streaming service, your best bet is to use a lossless codec, but a lossy codec can look great if the bit rate is high enough. Some studies have concluded that most listeners cannot tell the difference between an MP3 at 320Kbps and an uncompressed CD.

If you’re mainly listening through simple earbuds on your phone, or through the speakers on your laptop, or in a noisy environment like a car, even a low-quality stream can sound perfectly fine. But if you’re a true music lover with a high-quality audio system or headphones, the more advanced the codec and the higher the bitrate, the better your listening experience will be.