Bluetooth is a wireless technology that allows devices to communicate with each other over short distances.
Bluetooth audio codecs are used in a variety of applications, including the playback of audio files from handheld devices, the streaming of MP3s from car stereos, and the connection of wireless headsets. Also known as “wireless transmission protocols” or “wireless data exchange protocols,” these Bluetooth audio codecs are used for transmitting voice or music wirelessly.
We will explore and explain the different Bluetooth codecs as well as the benefits, capabilities, and pitfalls of each one. You will learn which Bluetooth codec to choose for your needs.
What Are Bluetooth Codecs?
Bluetooth audio has come a long way since the days when all it really did was sound like a bad cellphone connection, and that’s largely thanks to aptX. The proprietary codec, which promises “CD-like quality” sound over Bluetooth (and was open-sourced by Qualcomm in 2015), is found in more than 300 million products today — from Bluetooth headphones to speakers, TVs, and cars. But aptX isn’t the only game in town these days.
In recent years, we’ve seen a number of new codecs pop up that offer even better sound quality. But before we get into what those are, let’s first talk about what Bluetooth codecs are.
A Bluetooth codec is simply an algorithm for compressing data so it can be transmitted efficiently over wireless connections. In the case of sending music from your phone to a wireless speaker or pair of headphones, that means using less bandwidth to transmit the same amount of information.
If you’ve ever used a music streaming app like Spotify over a cellular connection, you’ll notice that songs play back at lower bit rates when compared with streaming over Wi-Fi. This is because cellular connections have much lower bandwidth than Wi-Fi networks.
That’s why it’s important to have good Bluetooth codecs: they let you play music over your wireless network while using less bandwidth than a cellular connection.
Types of Bluetooth Codecs
The Bluetooth standard supports many different codecs, and the codec a device uses can have a major impact on sound quality.
Low-complexity Sub-band Codec (SBC)
The most common codec is SBC (subband coding), which is mandated by the Bluetooth standard. It’s used in almost all Bluetooth headphones and speakers, with the sole exception being Qualcomm’s aptX family of codecs (more on that later). SBC is also used in virtually all Bluetooth audio senders, including smartphones, tablets and computers.
While SBC offers good compression ratios, it has a number of drawbacks. Since it uses a relatively simple algorithm, it’s subject to bit errors that degrade sound quality. It’s also very data-intensive, so it tends to be slow.
Finally, since there are only 256 possible audio signal combinations in SBC, a lot of additional information must be stored in Bluetooth devices to represent this data. This can slow down iOS devices when they’re trying to send big files or run a lot of apps at the same time.
Qualcomm aptX, aptX LL, aptX HD, and aptX Adaptive
aptX is a proprietary high-quality Bluetooth codec owned by Qualcomm. It’s been around for decades and is widely used in consumer electronics. While it’s not as good at reproducing music as the best wired hi-fi equipment, it’s not far behind. There are multiple versions of aptX Classic, Low Latency (LL), High Definition (HD), and Adaptive, each offering an increasing level of quality.
aptX Classic offers CD-like 16-bit/44.1kHz audio at 352 kbps or better. In our testing, this codec has consistently produced excellent results with virtually no latency and relatively easy pairing compared to other codecs. However, some devices using aptX Classic actually stream at lower bit depth than others using SBC, so there are no guarantees that aptX Classic will perform better than SBC until you try it yourself.
aptX Low Latency (LL) was launched by Qualcomm in 2016 as a solution for latency issues with Bluetooth audio. This codec allows for real-time streaming of audio with less than 32 milliseconds of latency between the transmitter and receiver. The low latency also makes it easier to have a conversation while wearing two Bluetooth earbuds at the same time.
aptX HD is a high-definition codec capable of streaming 24-bit/48kHz audio at 576 kbps or better. It sounds fantastic and its performance is comparable to wired hi-fi equipment, almost indistinguishable from a wired connection in our testing. However, it’s so much more demanding than other codecs that it drains battery life quickly and often has problems pairing with other devices. In our experience, aptX HD is best reserved for home use rather than on the go.
aptX Adaptive is Qualcomm’s newest codec and is designed for gaming or video streaming applications where latency isn’t as important as consistent sound quality. It can change its bitrate dynamically to get the best sound for the situation, but it will never go above the 576 kbps bitrate of aptX HD.
Advanced Audio Coding (AAC)
AAC is the most widely used lossy format, making it a staple for Apple users. AAC is found in iTunes as well as on iOS devices like the iPhone and iPad. In terms of sound quality, AAC is better than MP3, but not quite as good as Ogg Vorbis. The aforementioned compression doesn’t compromise sound quality like MP3 encoding does, and file sizes are typically smaller than MP3 files.
Sony LDAC is an audio technology from Sony that allows streaming of high resolution (hi-res) audio over Bluetooth connections up to 990 kbps at 24 bit/96 kHz. The technology claims to offer a transmission rate three times greater than standard Bluetooth audio, which in turn can deliver high-resolution audio content. Sony LDAC enables the transmission of 24bit/96kHz Hi-Res audio content, as well as other file formats such as SBC, AAC, and aptX.
HWA Alliance’s LHDC and LLAC Codecs
The HWA Alliance is an alliance of many smartphone manufacturers from China. They’re behind the popular audio codecs, LDHC and LLAC.
LDHC and LLAC are Bluetooth codecs that offer really good audio quality, better than aptX or aptX HD. You’ll find LDHC on smartphones like the OnePlus 7T Pro or Xiaomi Mi 9T Pro, while LLAC is found on phones like the Huawei Mate 20 Pro or Honor Magic 2.
Both LDHC and LLAC are proprietary codecs that are not available to third-party manufacturers. So you will only find these audio codecs on smartphones that support it internally. If a third-party manufacturer wanted to implement this in their headphones or speakers, they’d have to pay royalties to the HWA Alliance.
Bluetooth LE Audio LC3 Codec
This is a new codec introduced in Bluetooth 5.2. It promises to deliver superior audio quality and lower latency than previous codecs. As a result, it improves the listening experience for wireless audio devices. Improved sound quality doesn’t require a lot of extra bandwidth or electricity. The LC3 codec is a good choice.
The LC3 is designed to be backwards compatible with the SBC codec, while providing better audio quality and increased battery life.
It offers greater bitrates (maxing out at 768 kbps), which means audio files can be transmitted more efficiently. This allows for higher-quality streaming, including lossless audio.
Samsung Scalable Codec
Samsung’s own codec, which is built into the new Galaxy S9. It offers more flexibility than the SBC and AAC. It can use three sub-bands (instead of one), and can dynamically drop down to a single sub-band if audio quality is suffering in a noisy environment. There’s also an optional high-quality mode for when you’re listening through headphones that don’t have very good noise isolation, like AirPods or in-ear headphones.
At the moment, Samsung phones are the only ones that support it. But hopefully, other manufacturers will add support soon, since it has the potential to become the next big Bluetooth audio standard.
Which Bluetooth Codec Should I Choose?
The Bluetooth standard supports several different Bluetooth codecs, each of which uses a different algorithm to compress the digital audio. Each codec has its own advantages and disadvantages. When you buy a Bluetooth product, the codec you choose can have a big impact on how you listen to it.
The codec you get will depend on the devices you’re using. Smartphones, tablets, and computers may only be able to play one or two codecs because they don’t have a lot of processing power or energy. However, most modern headphones and speakers can play more than one codec.
The default codec, SBC, is generally considered to deliver subpar audio quality. The good news is that the iPhone 7 supports the AAC codec and most Android phones support the aptX codec, which typically offers better sound quality.
Note that Apple devices do not support the aptX codec, so if you’re using an iPhone and want to take advantage of aptX, you’ll need to pair it with another device that also supports aptX, such as certain Android phones, PCs, and Macs (with a plugin).
However, if you want the best possible audio quality, then you should choose LDAC or LLAC.
How Does Bluetooth Work?
Bluetooth is a wireless technology. It’s short-range, low-power and used to transmit data between devices. Chances are you’ve got at least one of these wireless devices in your pocket: a mobile phone, wireless headset, or fitness tracker.
But how does Bluetooth actually work? When you’ve got two Bluetooth-enabled devices like your phone and your wireless headphones, how do they communicate?
It’s all about radio waves. Bluetooth uses what’s known as frequency hopping spread spectrum (FHSS) technology. This means that the data transmitted from one device to another “hops” around frequencies in the 2.4 GHz range. In other words, it’s constantly switching frequencies so it can send and receive data without interference from other devices.
Bluetooth is managed by the Bluetooth Special Interest Group (SIG), which has more than 30,000 member companies in the areas of telecommunication, computing, networking, and consumer electronics.
The IEEE standardized Bluetooth as IEEE 802.15.1, but no longer maintains the standard. The Bluetooth SIG oversees development of the specification, manages the qualification program, and protects the trademarks.
A manufacturer must meet Bluetooth SIG standards to market it as a Bluetooth device. A network of patents apply to the technology; these are licensed to individual qualifying devices.
Does Bluetooth 5.0 Support aptX?
Bluetooth 5.0 has been released since June 2016, and aptX is a codec that allows you to transmit high quality audio via Bluetooth. Many people are wondering if Bluetooth 5.0 supports aptX. Well, the answer is yes, but you will need the right device that supports it to be able to use it.
Can Bluetooth Handle FLAC?
Yes, you can transmit FLAC audio over Bluetooth.
Does Bluetooth Support Dolby Atmos?
Bluetooth does not support Dolby Atmos. But that doesn’t mean you can’t enjoy your Dolby Atmos setup and listen via Bluetooth headphones.
Headphones that support Dolby Atmos can use the technology, but they are connected to a device with Dolby Atmos capabilities via a wired connection, such as a USB-C or 3.5mm port.
What Is the Maximum Range of Bluetooth Technology?
According to the BluetoothSpecial Interest Group, Bluetooth is the wireless technology that enables simple, short-range connections between devices such as cell phones and headphones, and has a maximum range of about 30 feet.
As you can see, there’s certainly a lot involved when it comes to Bluetooth audio and codecs. But whether you’re an audiophile or just someone who wants their music to sound as good as possible, this information is essential. Armed with the details in this guide, you’ll be able to make the right decisions regarding Bluetooth devices—whether they’re speakers, phones, or headphones.