With the rise in popularity of wireless headphones and earbuds, a lot of technical terms have come along with them. From wireless charging to Bluetooth multipoint, wear sensors, ANC and transparency, IPX ratings, and spatial audio, it can all get pretty confusing.
Most of these terms are relatively easy to understand, but one term that can be particularly puzzling is Bluetooth codecs. What exactly are they, and why should you even care about them? We’ll break it down in simple language so that next time you come across a headphone review that mentions aptX, AAC, or LDAC support, you’ll know what it means. More importantly, you’ll understand how it could impact your listening experience.
Let’s get into it.
What is a Bluetooth codec?
Bluetooth, as a wireless technology, has traditionally been fairly limited in terms of bandwidth. Each new version of Bluetooth (we’re up to version 5.4 as of 2024) adds a bit more bandwidth than its predecessor, but it’s still nowhere near as capacious as, say, Wi-Fi.
Because some kinds of digital audio can be too massive to be streamed in real-time over that limited bandwidth, it needs to be re-packaged to fit. Bluetooth codecs are the key to that repackaging and streaming process.
The word codec, by the way, is a portmanteau for encoding and decoding, which is geek-speak for packaging and unpackaging, or perhaps more accurately for our purposes, compressing and decompressing.
Why is there more than one type of Bluetooth codec?
As with all things technological, improvements get made over time as we get better at creating software and hardware. When wireless stereo headphones first appeared, there was only one Bluetooth codec: SBC, or sub-band codec. And to this day, if your phone, computer, headphones, or earbuds only supports one codec, it’s SBC.
SBC is reliable and always gets the job done, but it wasn’t built for high-quality or low-latency applications. In the early 2000s, when stereo audio was added to Bluetooth, the highly-compressed MP3 file format still reigned supreme. Today’s music streaming services hadn’t arrived, and almost nobody was talking about the need to support lossless music in 24-bit/96kHz. Mobile gaming still was many years from becoming mainstream.
But as these scenarios started to creep closer to center stage, it became apparent that we needed new codecs that could take us beyond SBC’s limitations. We now have at least 10 Bluetooth codecs that exceed SBC in some way. Some offer lower latency (the time it takes from when your device makes a sound to when your headphones let you hear that sound), some offer higher quality audio, some are built to be more energy efficient, and some try to do a little bit of everything. And as of 2024, the list of beyond-SBC Bluetooth codecs is astonishingly long:
- AAC
- Airia (SCL6), formerly known as MQair
- aptX
- aptX Low Latency (LL)
- aptX HD
- aptX Adaptive
- aptX Lossless
- LDAC
- LHDC/LLAC
- LC3
- Samsung Scalable Codec (SSC)/Seamless Hi-Fi Codec
Do I need to care about Bluetooth codecs?
No need to worry if you’re feeling overwhelmed. Unless you’re a competitive gamer needing super-fast response times or an audiophile seeking top-notch sound quality, you can probably stop reading.
While specific wireless features may only be fully appreciated with certain codecs, the good news is that all Bluetooth devices support SBC. So, even if you’re unfamiliar with these codecs, your chosen audio products will still work together smoothly.
How do Bluetooth codecs work?
As the word codec implies, if you encode information, you need to be able to decode it on the other end, and codec compatibility is key. For a codec to work, it needs to be supported on both the sending and receiving ends. If your earbuds support aptX, for instance, but your phone doesn’t, you won’t be able to use the aptX codec.
When two Bluetooth devices connect, they relay which codecs they support. In general, they will default to the highest quality mutually supported codec. So if two devices support aptX, they’ll use that instead of SBC.
But if they can’t find any common ground — e.g. one supports AAC but not aptX, and the other supports aptX but not AAC — they will fall back on good ol’ SBC.
This is where I have some bad news for Apple fans. Your iPhone, iPad, Apple Watch, and to a lesser degree your Macs, only support two codecs: SBC and AAC — neither of which supports lossless audio, hi-res, 24-bit audio, or low-latency operation.
Android owners have more options, but beware: Android is a highly fragmented world in which some handsets support virtually all of the most common codecs, while others only support some. Google’s Pixel phones are a good example. They support AAC, LDAC, and both aptX and aptX HD, but they don’t support Qualcomm’s aptX Adaptive or aptX Lossless codecs.
What’s the difference between Bluetooth codecs?
As previously mentioned, since the introduction of SBC, codecs have been striving to enhance sound quality, reduce latency, and improve energy efficiency. However, achieving all three simultaneously is challenging, as prioritizing one or two aspects often comes at the expense of the third.
To enhance latency and energy efficiency, a codec can minimize computational processing, but this typically results in reduced sound quality. Conversely, pursuing higher-quality sound through increased bandwidth or complex audio processing may lead to heightened latency and reduced battery life.
Both of these trade-offs are acceptable if they align with your priorities. Hence, the existence of numerous codecs.
Now, let’s explore the specific advantages provided by each Bluetooth codec.
Sub-band Codec (SBC)
Pros:
- Supported by all Bluetooth devices
- Decent audio quality for casual listening
Cons:
- Old standard that hasn’t been optimized for newer devices
- Can suffer from longer latency
- Doesn’t support hi-res or lossless audio
Advanced Audio Coding (AAC)
Pros:
- Default high-quality codec for all Apple devices
- Very good audio quality
Cons:
- More demanding of battery life because of greater computational complexity
- Can suffer from poorer performance and longer latency, especially on Android devices
- Doesn’t support hi-res or lossless audio
Low Complexity Communication Codec (LC3)
Pros:
- Designed to be more power-efficient than other codecs
- Supports bit-depths up to 32-bit
- Lower latency than SBC and AAC
- Works with both hearing aids and wireless audio products
Cons:
- Doesn’t support lossless audio
Qualcomm aptX family codecs (aptX, aptX HD, aptX LL, aptX Adaptive, and aptX Lossless)
Pros:
- Lower latency, less computationally demanding than AAC, especially aptX LL
- More energy efficient than SBC
- Capable of hi-res lossy audio up to 24-bit/96kHz (aptX HD, aptX Adaptive) or 16-bit/44.1kHz CD-quality lossless audio (aptX Lossless)
- The most widely supported hi-res codecs on wireless headphones and earbuds (aptX HD, aptX Adaptive)
- Can adjust on the fly to wireless and audio conditions to maintain maximum quality (aptX Adaptive)
- The first (and currently only) lossless Bluetooth codec (aptX Lossless)
Cons:
- Not supported on Apple devices
- Not always included by default on Android devices (aptX Adaptive/Lossless)
- Can be confusing due to the number of different versions
LDAC
Pros:
- Certified for hi-res, lossy audio up to 24-bit/96kHz
- Included within the Android operating system since version 8.0
- Supported by all of Sony’s flagship wireless headphones, earbuds, soundbars, and a variety of other audio devices
Cons:
- Not supported on Apple devices
- Can be very power-hungry
- Sometimes high latency makes it a poor choice for gaming/watching TV or movies
- Headphone/earbud support is less common than aptX codecs
- Best audio quality requires short distances between devices, with little or no interference from other wireless signals
Low Latency High-Definition Audio Codec (LHDC/LLAC)
Pros:
- Certified for hi-res, lossy audio up to 24-bit/96kHz
- Latency comparable to aptX LL (LLAC)
- Available as a license-free option within the Android operating system since version 10.0
Cons:
- Not supported on Apple devices
- Hard to find on Android devices
- Low support among major headphone makers
Samsung Scalable Codec (SSC) / Seamless Hi-Fi Codec
Pros:
- Support for hi-res, lossy audio up to 24-bit/96kHz
- Can adjust on the fly to wireless and audio conditions to maintain maximum quality (aptX Adaptive)
Cons:
- Only available when you use a compatible Samsung phone and Samsung earbuds
Airia (SCL6), formerly MQair
Pros:
- It works for broadcast and streaming across wireless protocols like Bluetooth, Ultra-Wide Band (UWB), and Wi-Fi
- It can dynamically adjust the data rate based on the connection’s available bandwidth
- Compatibility: Under the right conditions, Airia can transmit the MQA audio codec, making it the only Bluetooth codec that can do so
Airia’s MQA compatibility will be of questionable value in the short term: Tidal, the only major streaming service to offer tracks in the MQA format, has almost finished its transition to FLAC, leaving MQA fans without readily available source.
However, longer term, this may change: Lenbrook (the company that owns the rights to MQA and Airia) recently announced a partnership with HDtracks to create a new streaming service that will work with both MQA and Airia. It’s just not entirely clear how a streaming service interacts with a Bluetooth codec.
Cons:
- Limited adoption
- Potential licensing cost
- Learning curve
Bluetooth codec buying advice
So, when it comes right down to it, does any of this matter when choosing a new set of wireless earbuds or headphones, or possibly a phone? Yes and no.
Buying for sound quality
A million variables go into wireless headphones. Things like audio source and driver size. Or design and materials. The quality and power of amplification. The use of digital signal processing, quality of digital-to-analog conversion, and the Bluetooth codec being used. It all factors into sound quality. But even then, the codec would be among the least important ingredients.
In other words, a hi-res codec like aptX Adaptive or LDAC cannot make a lower-quality set of cans sound better, just like putting high-octane fuel in a minivan won’t turn it into a sports car.
So if you’re buying a budget set of earbuds or headphones — and you’re not into gaming — codecs probably are not something you need to worry about.
I’ve listened to several sub-$100 earbuds that sound great, even though they only support the base-level SBC codec.
But if you’re looking to make a big investment in wireless earbuds or headphones in order to get top-quality sound, codecs can and do make a difference. I’ve auditioned high-end headphones like Bowers & Wilkins Px7 S2, Master & Dynamic MW75, or the crazy-expensive Mark Levinson No.5909 and Dali IO-12, which all support either LDAC or aptX Adaptive (and sometime both). I’ve alternated between an iPhone with AAC and an Android device with LDAC or AptX Adaptive, the difference was immediately noticeable.
When using these hi-res codecs, detail, dynamic range, and soundstage accuracy were all improved. Would you notice the difference if you were listening to a low-bit rate Spotify stream while commuting on a busy bus or train? Not a chance. But if you have access to hi-res, lossless content via a streaming service or your own personal collection of music, and you can find a quiet place to chill, it’s the bees’ knees.
Buying for gaming performance
Gamers — particularly those who play rapid-action first-person shooters or other genres where reaction speed is critical — need to be on the lookout for products that offer low-latency codecs. Latency is measured in milliseconds and is best described as the time between an on-screen flash that you see, and the corresponding bang that you hear. The lower that time, the faster you’ll be able to react to what’s happening in your game.
The absolute best way to reduce latency for gaming is to buy a set of gaming headphones or earbuds that come with their own dedicated wireless transmitter. This sidesteps the question of Bluetooth altogether, delivering latency as low as 20 milliseconds — we’re talking 20-thousandths of a second. A good example is Angry Miao’s Cyberblade wireless earbuds, which clock in at around 36ms.
But for a more flexible solution, you can look for a set of wireless headphones that support aptX LL. With delays measuring between 30-40 milliseconds, this is about as close to a dedicated wireless setup as you can get. But there’s a catch.
Even though aptX LL is a Bluetooth codec, it’s not available on phones. It requires its own dedicated antenna instead of the antennas in phones that are often shared between Bluetooth and Wi-Fi connections. To get aptX LL, you’ll not only need a set of headphones that support it, like the Sennheiser HD 450BT, but also a dedicated aptX LL USB dongle that you can plug into your computer or game console.
When looking for headphones or earbuds for mobile gaming, it’s important to consider the latency times. While achieving latency times as low as aptX LL may not be possible, some headphones and earbuds offer a gaming mode or a low-latency mode, which can help reduce latency. This may involve the earbuds turning off additional sound processing to minimize latency, or utilizing Qualcomm’s aptX Adaptive technology to automatically adjust to the content being listened to. AptX Adaptive’s low-latency mode can reduce latency to under 100 ms, which is faster than both SBC and AAC and can have latency ranging from 150-300 ms.
