What Are Bluetooth Codecs? A Guide to Everything From AAC to SBC

In the early days of wireless audio, Bluetooth was lousy—the connection standard simply wasn’t capable of consistently and accurately transmitting sound the way a pair of wired headphones could via a 3.5mm connection. But the situation has improved dramatically, likely accelerated to some degree by Apple (and subsequently most Android handset manufacturers) removing the headphone jack from its phones. Wireless earphones and headphones are now the norm, and we rarely review wired models.

Audio quality improvements over Bluetooth are mostly due to the development of increasingly better codecs that enable near-lossless streaming. Before we run through the basics of each of these codecs below, the main thing to understand is that they largely determine the quality of your streaming audio.

Understanding Bluetooth Technology: It’s Like Delivering a Package

Before we get into the details of each codec, it’s important to understand the basics of Bluetooth itself.

Bluetooth 5.4 launched in February of 2023, but 5.3 is still the most common version we see and it largely defines how devices like phones and headphones connect. Older devices might use older Bluetooth versions such as 5.1 or 4.2, but backward compatibility means you can still connect them to newer listening devices with the latest standard. Just keep in mind that you won’t get all the connectivity benefits of a particular standard unless both the sending and receiving devices support the same one.

Think of the Bluetooth version as a road that a delivery truck drives down; a higher number means the road is smoother and wider, with a higher speed limit.

The Beats Studio Pro use Bluetooth 5.3 (Credit: Tim Gideon)

Although the Bluetooth version determines how devices connect to each other, it doesn’t define the type of data that can transmit between them—that’s what profiles are for. Bluetooth profiles are the standards and protocols for sending stereo audio, phone calls, photos, printer jobs, and even faxes over Bluetooth. A2DP, the Advanced Audio Distribution Profile, is the specification for sending high-quality sound over Bluetooth. In the above example, think of the Bluetooth profile as the truck itself and your music as a package on that truck.

The Most Common Bluetooth Codecs

Codecs encode and decode audio using different types of file compression to send as much information as possible given the available speed and bandwidth. Much of what distinguishes a codec comes down to bit depth (bits), bit rate (Kbps), and sampling rate (kHz), with higher numbers indicating higher quality.

Even if you store the highest-quality files on your device, how they sound through your Bluetooth headphones depends in part on the transmission codec. In most cases, the bit rate is what holds back even the high-end codecs from reaching CD quality (16-bit; 44.1kHz; 1,411Kbps) or better. Higher-end audio codecs like LDAC can support up to 32-bit and 96kHz sound, but only about two-thirds the bit rate of CD quality at best (990Kbps), so you still lose data in the process.

In brief, SBC is the most basic codec with the lowest bit rate and, therefore, the most basic sound quality. AAC and AptX are both steps up from SBC and are generally mainstream. AAC is the best you can do on Apple phones and tablets, while AptX is a step-up option on Android.

LDAC and LHDC enable even higher-quality sound and are currently the only ones to which the Japan Audio Society extends its Hi-Res Audio Wireless certification (that’s the gold and black Hi-Fi logo you see on high-end audio products).

Below are all the codecs you might encounter (in order of prevalence) when streaming audio over Bluetooth. We mention a couple of emerging codecs in this article, but you likely don’t need to worry too much about them unless you seek out devices and headphones that specifically support them.

Note that the specs we list apply to mainline applications; variations of each codec might be capable of different specs, but the implementation ultimately depends on the manufacturer.

SBC

SBC, or subband codec, is the default (and only) codec most lower-cost audio gear supports and is what devices often fall back on when higher-quality options aren’t available. SBC isn’t terrible—it’s capable of better-than-CD quality audio in terms of bit depth and sampling rate (16-bit and 48kHz, respectively), but that’s only under the most ideal circumstances. Latency with SBC is also high, which means it isn’t suitable for gaming. All Bluetooth devices must at least support SBC.

On good headphones and with good source material, you can likely easily hear the difference between playing audio over SBC and a higher-end codec, so we recommend that you use SBC only when you have no other choice.

The EarFun Air Pro 3 earbuds support LC3 (Credit: Tim Gideon)

The codec itself isn’t necessarily the limitation here, but rather how it’s usually implemented. A deep dive from the Lineage OS Project(Opens in a new window) details how the combination of SBC’s Dual Channel mode and eXtreme quality profile (SBC XQ) can produce results that rival AptX HD. A successor to SBC, LC3(Opens in a new window) (Low Complexity Communication Codec), which is now officially past the development stage, promises to be more efficient, support more bit depths (up to 32-bit), and work at a broader range of bit rates.

AAC

• Bit Depth: Up to 24-bit

• Sampling Rate: 44.1kHz

• Bit Rate: Up to 320Kbps

AAC (Advanced Audio Codec) is the Bluetooth codec Apple uses, but confusingly, it’s also the name of the file compression scheme the company leans on for storing music files as an alternative to MP3s.

The Apple AirPods Pro (2nd-Generation) support AAC (Credit: Tim Gideon)

SBC offers a (slightly) better sampling rate and maximum bit rate than AAC, though it performs worse, especially on Apple devices. This is because AAC uses a superior compression algorithm, and Apple’s phones, tablets, and headphones can run this potentially battery-guzzling codec efficiently. As a result, AAC sounds less lossy than SBC. It isn’t particularly low-latency, though, so like SBC it’s not ideal for gaming.

You can use AAC on Android phones, but that OS doesn’t usually process it as effectively, which leads to a loss in audio quality.

AptX

• Bit Depth: 16-bit (AptX); Up to 24 bits (AptX HD)

• Sampling Rate: 48kHz (AptX); 48kHz (AptX HD)

• Bit Rate: Up to 384Kbps (AptX); 576Kbps (AptX HD)

There are several versions of Qualcomm’s AptX codec, each with a distinct purpose. There’s standard AptX, AptX LL (low latency) for gaming, AptX HD for high-quality audio, and AptX Adaptive, which uses adaptive bit rates to offer a combination of lower latency and higher quality. AptX HD is the best option for audiophiles out of the bunch because its bit rate locks in at a high level.

The Jabra Elite 4 earphones support AptX (Credit: Tim Gideon)

Another AptX variant to keep an eye on is AptX Lossless. It combines some of the best qualities of AptX Adaptive and AptX HD. It uses an adaptive bit rate that scales from 140Kbps up to 1Mbps, which is even higher than LDAC. Support for this codec is still rare, but some phones and headphones are starting to ship with it on board.

Qualcomm has a helpful resource(Opens in a new window) for finding various products that support each of these standards, and AptX Lossless (Snapdragon Sound with AptX Lossless) is now an option in the drop-down menu.

LDAC

If you want to max out specs while streaming over Bluetooth, Sony’s LDAC codec offers gaudy capabilities. It streams at up to 990Kbps, with a sampling rate of up to 96kHz. It enables some of the highest-quality audio when it’s at its best, but its fallback modes are pretty much in line with the other codecs, as low as 16-bit and 330Kbps. You can force LDAC to always play at the highest bit rate, but doing so can affect playback if streaming conditions aren’t ideal. In contrast, AptX HD stays at a constant bit rate, so it might provide more consistency to your listening experience.

The Sony WF-1000XM5 earphones support LDAC (Credit: Tim Gideon)

Apple’s iOS devices don’t support LDAC, but because it’s part of the Android Open Source Project (AOSP), the vast majority of Android devices should. And, like most other codecs on this list, latency is also an issue on LDAC, so once again it’s not suitable for gaming.

LHDC

• Bit Depth: Up to 24-bit

• Sampling Rate: Up to 96kHz

• Bit Rate: Up to 1,600Kbps

LHDC(Opens in a new window) is a relatively new codec from Savitech and Huawei; it primarily competes with LDAC. LHDC 5.0’s bit rate scales dynamically up to 1,000Kbps, while the LHDC Lossless Audio(Opens in a new window) standard goes all the way up to 1,600Kbps (albeit at 16-bit/48kHz quality).

An additional variant called LLAC offers better latency but limits audio quality to 24-bit, 48kHz, and 600Kbps. Details about LHDC and LLAC are scarce and not easy to confirm, so these specs might not be exact.

The Nothing Ear (2) earbuds support LHDC 5.0 (Credit: Tim Gideon)

The codec benefits from Huawei’s adoption and it is a part of the AOSP, too.

Matching Phones, Tablets, and Computers With Codec Support

AAC is the highest-quality codec that Apple products support, but they default to transmitting over SBC when paired headphones don’t support that codec. So if you use an iPhone (or just about any Bluetooth-capable Apple product), you should make sure your headphones support AAC. You can often (but not always) find this information on the product’s specs page or on the box itself, and we always list this information in our reviews. For reference, AAC also seems to be the most common codec that headphones support apart from SBC based on those we have reviewed.

Android users need to pay even closer attention to codec support on headphones; if they only have AAC and SBC, they won’t provide the best audio quality possible, but that’s just the start. Look for at least aptX, but also consider whether your headphones use aptX HD, LDAC, and LHDC, depending on what your phone supports.

While Android phones aren’t usually capable of efficient AAC playback, they can work with different combinations of SBC, AptX (in various forms), LDAC, and LHDC, depending on both the processor in the device and the whims of the manufacturer. For example, the Snapdragon 8 Gen 2(Opens in a new window) chip is one of the few so far that supports the AptX Lossless codec. And though the Samsung Galaxy S23 Ultra ships with the 8 Gen 2, it does not support AptX Lossless.

Meanwhile, while LDAC and LHDC are technically part of AOSP, individual manufacturers can still choose whether to enable them on their devices, and LDAC seems to be supported more broadly than LHDC.

You can change the Bluetooth codec in the Settings menu of your Android phone (tap System > Developer Options > Bluetooth Audio Codec). With the LDAC codec specifically, you can set a streaming preference: Optimized for Audio Quality; Balanced Audio and Connection Quality; or Optimized for Connection Quality. That first option gets you to the highest 990Kbps bit rate.

Some manufacturers helpfully equip headphones and speakers with both AAC and AptX or LDAC, which saves you from having to think about sticking with a single platform for listening to music. But you still may need to manually switch between the two codecs in an app, your phone’s settings menu, or on your computer depending on your sound source.

Even if your device doesn’t support a specific codec, some software or hardware workaround likely exists. For example, it’s possible with some Macs to stream via AptX instead of AAC, but you have to manually set this up and the process is more involved than we have room to describe here. Similarly, you can buy external gear that you can use with iPhones and iPads to force support for other codecs, but again, this isn’t an ideal (or Apple-approved) solution. Windows 11 devices support AAC, but you must turn to alternative methods to use any of the other high-end codecs.

What About Apple Lossless and Other High-Res Streaming Audio?

Apple and other streaming services have joined Tidal to offer lossless streaming, but if you’re listening via Bluetooth, you’re not hearing it. Virtually all Bluetooth codecs are lossy, which means some data is lost in the compression and decompression process that lets the audio be transmitted wirelessly. That means the sound you get through your Bluetooth headphones won’t technically have as much detail as if you used a wired pair of headphones or a different wireless connection (such as Wi-Fi) that’s fast and wide enough to send all of that data without encoding.

Apple Music uses the company’s own lossless audio compression technology, called Apple Lossless Audio Codec (ALAC). So what happens when you listen to ALAC over Bluetooth headphones that only support AAC or SBC? The short answer is that you eliminate the lossless quality—the source device encodes the ALAC files to the AAC codec before transmission. Even on AirPods.

This isn’t really Apple’s fault and is more a result of the current limitations of Bluetooth. For instance, the most popular non-Apple lossless compression codec, Free Lossless Audio Codec (FLAC), still loses some data when sent over Bluetooth, at least until aptX Lossless or LHDC Lossless Audio becomes readily available. Apple Lossless being unavailable (at its highest fidelity, at least) on AirPods is somewhat ironic, but until Bluetooth upgrades to truly hi-res specs, no Bluetooth headphones or speakers can output ALAC or FLAC at its best.

This goes for every music streaming service out there, Apple or otherwise—no matter how “lossless” the stream may be, it becomes lossy once the source encodes the stream for Bluetooth transmission. Exactly how lossy depends on the codec.

When Codecs Don’t Matter (as Much)

Let’s be reasonable: The goal of a budget-friendly pair of headphones isn’t to produce superb audio. Most of these models stick with the SBC codec, and that’s fine because most of the drivers in these models are unable to produce crystal-clear, audiophile-grade audio anyway. This holds true for most headphones and speakers under about $100. Manufacturers also have to pay to license AAC or AptX support on their devices, which likely contributes to the decision to omit the codecs.

The JBL Charge 5 supports SBC only (Credit: JBL)

Bluetooth speakers are even less generous with high-end codec support—plenty of portable models that cost over $200 (and that we recommend enthusiastically) support only SBC. The reality is that pristine audio quality often takes a backseat to a list of other features in this category, like booming bass or a waterproof design. That doesn’t mean you can’t find quality codec support in Bluetooth speakers, but SBC-only portable speakers are the most common. 

There’s Still a Long Way to Go to Lossless

When televisions made the leap from CRT to flat-panel, letterbox-shaped screens, it was pure magic. But if you were to go back and watch a Blu-ray on an early LCD TV, you might find the resolution lacking and the color-banding problematic. Once you get used to something good (4K resolution, for example), it’s easier to see the flaws in older gear.

Bluetooth codecs are like that—they enable far better sound than early Bluetooth technologies, but there is still room for improvement. Latency remains an issue with most codecs, some of the better ones aren’t very energy-efficient, and frequency response can vary greatly.

Even if you load your phone with lossless uncompressed WAV files, no mainstream Bluetooth codec can currently transmit them without some level of compression. Until truly lossless codecs become the norm, you need to pay close attention to which ones your source device and headphones support—it’s a matter of ensuring that you get the least compressed audio quality possible.

Of course, you can also consider using one of our favorite pairs of audiophile headphones with a DAC/AMP, and bypass the whole issue of not having a headphone jack.