*** UPDATE FEB 16, 2022 ***
I should acknowledge as of WIndows 11, the AAC codec is natively supported in Windows (hooray!). Also, for an updated guide to 2022 bluetooth codecs, including their relative performance, check out this fantastic resource from Matija Feran at HeadphonesAddict.
I finally got a pair of wireless earbuds. I wanted them for zoom calls for our new remote way of life, but also for freedom and mobility while listening to music on my computer. But I soon learned that wireless earbuds, phones and computers don’t all necessarily play nicely together.
Specifically, if you’re an audiophile, you may have noticed that the same music played on your Windows computer through your earbuds sounds worse than when it is played through your Android or iOS phone (or vice versa). In both cases the music is being played over Bluetooth, but the difference lies in the codecs that are employed.
Patents, Bluetooth and Codecs
Bluetooth refers to a set of wireless standards that is overseen by a standard-setting organization called the Bluetooth Special Interest Group. The easiest way to think of it is that Bluetooth is a set of standards that replaces wires. The same data that normally passes through a wire can be wirelessly transmitted using a virtual wire called Bluetooth. That data can be many things – documents, information, and music.
But the virtual wire is only part of the story; it also matters how efficiently you can package information travelling on that virtual wire. To that end there are codecs. Codecs are software that encode and decode the music files that are passed between devices using Bluetooth. And here’s they key: just because technologies like Bluetooth and Bluetooth codecs are standardized, that doesn’t meant they’re free to use. Many of the best audio codecs are proprietary and covered by patents. A company that wants to incorporate them into their products may need to pay significant licensing fees.
Why Your Earbuds Sound Bad
Because licensing each codec can cost money, companies often pick and choose to keep costs down. Unfortunately, that means that where there is no overlap in compatibility, your devices will default to a mandatory and broadly compatible codec called SBC (Sub-band Coding). For a variety of reasons that I’ll leave to others to explain, “it’s never been SBC’s job to provide you with a high-end listening experience.”
Qualcomm owns a proprietary family of codecs called aptX that range in their ability to allow high quality music streaming. Meanwhile, a rival codec called AAC was developed by a set of companies including Bell Labs, Dolby, Fraunhofer, LG Electronics, NEC, NTT Docomo, Panasonic, Sony Corporation, ETRI, JVC Kenwood, Philips, Microsoft, and NTT. LDAC is another proprietary codec, developed by Sony. Both devices involved (e.g. phone and earbuds) need to support the same codec to use it.
To make matters more complicated, sometimes the codecs are offered for free for encoding but require licenses for decoding. That encourages people and companies to adopt use of the codec, but receiving device manufacturers (e.g. wireless earbud manufacturers) still need to pay license fees.
What emerges is a messy compatibility matrix. Devices that have Qualcomm chips tend to support aptX codecs. Apple and Huawei earbuds that don’t use Qualcomm chips support AAC and SBC. Windows-based devices can just default to SBC (for example, if you try to use your Airpods with your Dell Laptop), but also support others (just not AAC). LDAC might also be available on your Android device, but you might need to do some work to use it (assuming your earbuds support it too).
The Future of Audio Codecs and Bluetooth
There have been many promises over the years that the situation will get better. One codec to rule them all would be great. A codec called LC3 is being hailed as the default replacement for SBC that could finally do it. But for now, while the world of audio codecs remains fragmented, unfortunately you’ll still need to navigate the Bluetooth codec maze to get great sound from your earbuds.