With the surge in popularity of wireless headphones and earbuds, a plethora of technical terms have emerged. From wireless charging to Bluetooth multipoint, wear sensors, ANC and transparency, IPX ratings, and spatial audio, the landscape can seem confusing. While many of these terms are relatively straightforward, one that often puzzles users is Bluetooth codecs. This article aims to demystify Bluetooth codecs, explaining what they are, why they matter, and how they impact your listening experience.
Understanding Bluetooth Codecs
Bluetooth, as a wireless technology, traditionally has limited bandwidth. Each new version (we are currently at version 5.4) offers increased bandwidth, but it still pales in comparison to, for instance, Wi-Fi. Streaming certain digital audio formats in real-time over this limited bandwidth requires repackaging. This is where Bluetooth codecs come into play. They act as the key to this repackaging and streaming process.
The term “codec” is a portmanteau of “encoding” and “decoding,” essentially meaning packaging and unpacking, or more accurately, compressing and decompressing for our purposes.
Why Multiple Bluetooth Codecs?
Like most technologies, advancements are made over time through improvements in software and hardware. When wireless stereo headphones first appeared, there was only one Bluetooth codec: SBC (Sub-band Codec). To this day, if your phone, computer, headphones, or earbuds support only one codec, it’s SBC. SBC is reliable and functional but wasn’t designed for high-quality or low-latency applications.
In the early 2000s, when stereo audio was introduced to Bluetooth, the highly compressed MP3 file format was dominant. Today’s music streaming services didn’t exist, and lossless music in 24-bit/96kHz was a niche concept. Mobile gaming was also years from mainstream adoption. However, as these scenarios emerged, the need for codecs beyond SBC’s limitations became apparent.
We now have at least 10 Bluetooth codecs that surpass SBC in various aspects. Some offer lower latency (the delay between your device playing a sound and your headphones reproducing it), some offer higher-quality audio, some are designed for energy efficiency, and some aim to achieve a balance of these factors.
As of 2024, the list of beyond-SBC Bluetooth codecs is extensive:
* 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 Worry About Bluetooth Codecs?
Don’t fret if you feel overwhelmed. Unless you’re a competitive gamer requiring super-fast response times or an audiophile seeking top-notch sound quality, you can likely skip this section. While specific wireless features may be fully appreciated with certain codecs, all Bluetooth devices support SBC, ensuring that your audio products will work together smoothly even if you’re unfamiliar with these codecs.
How Bluetooth Codecs Work
As the word “codec” suggests, if you encode information, you need to be able to decode it on the receiving end, making codec compatibility essential. For a codec to work, it must be supported by both the sender and receiver. If your earbuds support aptX, for example, but your phone doesn’t, you won’t be able to use the aptX codec.
When two Bluetooth devices connect, they communicate their supported codecs. Typically, they will default to the highest quality mutually supported codec. So, if both devices support aptX, they will use it instead of SBC. However, if they lack common ground (e.g., one supports AAC but not aptX, and the other supports aptX but not AAC), they will revert to SBC.
Here’s some unfortunate news for Apple fans: your iPhone, iPad, Apple Watch, and to a lesser extent, your Macs, only support two codecs: SBC and AAC. Neither of these codecs support lossless audio, hi-res, 24-bit audio, or low-latency operation. Android users have more options, but it’s a fragmented world where some handsets support almost all common codecs, while others support only a few. Google’s Pixel phones are a good example. They support AAC, LDAC, and both aptX and aptX HD, but not Qualcomm’s aptX Adaptive or aptX Lossless codecs.
The Differences Between Bluetooth Codecs
Since the introduction of SBC, codecs have been striving to improve sound quality, reduce latency, and enhance energy efficiency. However, achieving all three simultaneously is challenging, as prioritizing one or two aspects often compromises the third. To improve 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. These trade-offs are acceptable if they align with your priorities. This explains the existence of numerous codecs.
Now, let’s examine the specific advantages of each Bluetooth codec:
SBC
*
Pros:
Supported by all Bluetooth devices, decent audio quality for casual listening.*
Cons:
An old standard that hasn’t been optimized for newer devices, can suffer from longer latency, doesn’t support hi-res or lossless audio.AAC
*
Pros:
Default high-quality codec for all Apple devices, very good audio quality.*
Cons:
More demanding of battery life due to greater computational complexity, can suffer from poorer performance and longer latency, especially on Android devices, doesn’t support hi-res or lossless audio.aptX
*
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.aptX Low Latency (LL)
*
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.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)
*
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, does any of this matter when choosing new wireless earbuds or headphones, or possibly a phone? The answer is both yes and no.
Numerous factors contribute to the quality of wireless headphones, such as audio source, driver size, design, materials, amplification power, digital signal processing, digital-to-analog conversion quality, and the Bluetooth codec used. All of these elements play a role in sound quality.
However, even considering these factors, the codec is often among the least important elements. In other words, a high-resolution codec like aptX Adaptive or LDAC cannot magically improve the sound quality of a lower-quality set of headphones. It’s like trying to turn a minivan into a sports car by using high-octane fuel.
Therefore, if you’re purchasing budget earbuds or headphones and aren’t interested in gaming, codecs are unlikely to be a major concern. I’ve listened to several sub-$100 earbuds that sound great, even though they only support the basic SBC codec.
But if you’re investing in high-quality wireless earbuds or headphones to achieve top-notch sound, codecs can make a difference. I’ve auditioned high-end headphones like Bowers & Wilkins Px7 S2, Master & Dynamic MW75, or the exceptionally expensive Mark Levinson No.5909 and Dali IO-12, all of which support either LDAC or aptX Adaptive (sometimes both). When switching between an iPhone with AAC and an Android device with LDAC or AptX Adaptive, the difference was immediately noticeable. Using these high-resolution codecs improved detail, dynamic range, and soundstage accuracy.
Would you notice the difference while listening to a low-bit rate Spotify stream during a noisy commute? Probably not. However, if you have access to high-resolution, lossless content through a streaming service or your personal music collection and can find a quiet space to enjoy it, the difference is remarkable.
Gamers, particularly those playing fast-paced first-person shooters or other genres where reaction speed is critical, should seek out products offering low-latency codecs. Latency is measured in milliseconds and represents the delay between a visual cue (like an on-screen flash) and the corresponding auditory cue (like a bang). The shorter the delay, the faster you can react to in-game events.
The most effective way to minimize latency for gaming is to purchase gaming headphones or earbuds with their own dedicated wireless transmitter. This completely bypasses Bluetooth, achieving latency as low as 20 milliseconds (20-thousandths of a second). A good example is Angry Miao’s Cyberblade wireless earbuds, with latency around 36ms.
For a more versatile solution, look for wireless headphones supporting aptX LL. With delays between 30-40 milliseconds, it’s as close to a dedicated wireless setup as you can get. However, there’s a catch: even though aptX LL is a Bluetooth codec, it’s not supported by phones. It requires a dedicated antenna instead of the shared antennas in phones that are often used for Bluetooth and Wi-Fi connections. To utilize aptX LL, you need headphones supporting it (like the Sennheiser HD 450BT) and a dedicated aptX LL USB dongle that you can plug into your computer or game console.
When searching for headphones or earbuds for mobile gaming, consider latency times. Achieving the low latency of aptX LL might not always be possible, but some headphones and earbuds offer a gaming mode or low-latency mode to help reduce latency. This might involve turning off additional sound processing to minimize delay 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 100ms, faster than both SBC and AAC, which can have latency ranging from 150-300ms.
