Bluetooth codec is not something that most people pay attention to when buying or using wireless devices, but it can make a big difference in your audio enjoyment.
By knowing what codecs your devices support and how to choose the best one for your needs, you can optimize your wireless audio experience and get the most out of your Bluetooth devices.
This Headphone 101 guide explains what Bluetooth codec is, why it matters for wireless headphones and earbuds, how to compare different Bluetooth codecs for headphones and earbuds, commonly used Bluetooth codecs (SBC, AAC, LC3, aptX, aptX HD, aptX Low Latency, aptX Adaptive, LDAC, LHDC, Samsung Seamless Codec (SSC), SCL6, LC3plus) for headsets, and how to properly consider the Bluetooth codec when buying or evaluating new wireless headphones and earbuds.
What is Bluetooth codec, and why does it matter for wireless headphones and earbuds?
However, Bluetooth has a limited bandwidth, which means it can only transfer a certain amount of data per second, usually capped at 2Mbps. This poses a challenge for audio transmission because audio files are usually large and require a lot of bandwidth, usually exceeding the capacity of Bluetooth, to stream without losing quality or interruptions.
To solve this problem, Bluetooth uses a codec to compress the audio data before sending it (e.g., from your phone) and then decompress it by the receiving devices (e.g., headphones and earbuds) after receiving it. A codec is software or hardware that encodes and decodes data using a specific algorithm. By compressing the audio data, the Bluetooth codec reduces the size of the file and the amount of bandwidth needed to transmit it. However, compression also involves some trade-offs, such as loss of quality, latency, and power consumption.
Essentially, Bluetooth codec is a software format that compresses and then encodes audio data so that it can be efficiently transmitted wirelessly between devices before being decoded by hardware that supports that same codec. In other words, a codec determines how your music is packed (compressed) and unpacked (uncompressed) when it travels from your phone to your headphones (and earbuds).
However, not all codecs are created equal. Sound quality can vary among codecs due to factors like bit depth, bit rate, sampling rate, and compression algorithm. These factors affect how much information is lost or preserved during the encoding and decoding process.
Therefore, it is important to understand the Bluetooth codec if you want to get more from your wireless headphones and earbuds.
Commonly used Bluetooth Codecs for wireless headphones and earbuds
There are different types of Bluetooth codecs, each with its own advantages and disadvantages. Some of the most common ones are:
- aptX HD
- aptX Low Latency
- aptX Adaptive
- Samsung Seamless Codec (SSC)
We now go through them one by one briefly. A detailed technical explanation will be covered in individual posts due to the length of this post.
SBC stands for Subband Coding and is the default and mandatory codec for all Bluetooth devices. It means all Bluetooth audio devices support this codec. To be precise, it is part of the Bluetooth A2DP profile.
SBC is a low-complexity Bluetooth codec that offers acceptable sound quality and low power consumption but also high latency and low compression ratio. It supports a maximum bitrate of 345 kbps.
AAC stands for Advanced Audio Coding and is a popular Bluetooth codec for Apple devices. Some people may mistakenly link the codec to Apple. Apple is simply the most prominent user and spends a lot of effort to optimize it for its devices.
Although AAC is as popular as SBC, partially thanks to Apple, it is not free. Hardware manufacturers, including Apple, must pay license fees for each device with AAC support. However, software developers and streamers usually do not need a license for it.
AAC is confusingly also referred to as the audio codec (file format), similar to MP3, Ogg, and FLAC. The AAC file format (usually .aac and .m4a) and the AAC Bluetooth codec are related but different things. AAC is an audio coding standard for lossy digital audio compression. It was developed to be the successor of the MP3 format. The AAC Bluetooth codec, on the other hand, is a way to compress and transmit audio data over a Bluetooth connection. It is a standard that is used to optimize the audio quality and reduce the amount of data that needs to be sent over the wireless connection.
In a nutshell, the AAC file format is a way to store (compress/decompress) audio files, while the AAC Bluetooth codec is a way to transmit audio over a Bluetooth connection. You can use the AAC Bluetooth codec to stream music files in any format, for example, MP3, FLAC, Ogg, or AAC.
AAC is a high-quality Bluetooth codec that offers better sound quality and compression ratio than SBC but also higher latency and power consumption. It supports a maximum bitrate of 320 kbps.
However, its performance can vary depending on the device and implementation. For example, Apple devices generally deliver better sound quality with AAC Bluetooth codec than Android devices.
LC3, Low Complexity Communication Codec, is the latest audio codec specified by the Bluetooth Special Interest Group (SIG) for the LE (Low Energy) Audio protocol introduced in Bluetooth 5.2. It was developed by Fraunhofer IIS and Ericsson as the successor of the SBC codec as part of the next generation of Bluetooth audio. It is free as part of the Bluetooth standard. Android 13 and Android 14 support it already.
LC3 is designed for use in LE (Low Energy) Audio profiles. It is capable of encoding speech and music at various bitrates and can be incorporated into any Bluetooth audio profile. LC3 scales down to very low bit rates while retaining good audio quality. This ensures data is correctly sent over the limited bandwidth of Bluetooth LE, even in congested radio conditions.
aptX is a Bluetooth audio codec developed by Qualcomm that offers improved audio quality over the standard SBC codec. aptX achieves this by using a different algorithm to encode and decode audio data. This algorithm is designed to preserve more of the original audio information, resulting in clearer, more detailed sound.
In addition to the improved audio quality, aptX has lower latency than SBC, which means that there is less of a delay between the time that audio is played on the source device and the time that it is heard on the receiver.
aptX codec is widely supported by Android phones and some middle to high-end wireless headphones. But Apple devices and Sony headphones do not support it.
aptX HD is an enhanced version of aptX codec that supports 24-bit audio and a sampling rate of up to 48 kHz. This means that it can reproduce a wider range of frequencies and deliver even clearer, more detailed sound than the original aptX codec.
However, it also consumes more battery power and requires compatible devices. It supports a maximum bitrate of 576 kbps. The power consumption is considerably higher than aptX.
aptX Low Latency (aptX LL)
aptX LL (Low Latency) is an enhanced version of aptX codec that is specifically designed for applications where low latency is critical, such as gaming and watching movies. It achieves this by reducing the latency to as low as 30 milliseconds with a maximum bitrate of 352 kbps.
aptX Adaptive is the newest Bluetooth codec in the aptX family. It is designed to dynamically adjust the bitrate (from 279 kbps low latency to 420 kbps high-quality playback) and latency (as low as 50-80ms) of the audio stream based on the current usage conditions.
Thanks to its dynamic bitrate and new algorithms, the power consumption of aptX Adaptive is noticeably lower than that of aptX HD.
LDAC, Lossless Digital Audio Codec (not acknowledged by Sony), is the hi-res audio codec developed by Sony that offers the highest bitrate (up to 990kbps) and resolution (up to 24 bits/96 kHz) among Bluetooth codecs in the current headphone market, delivering near-lossless sound quality. However, it also has the highest latency and power consumption. Android has had LDAC codec support since Android Oreo (Android 8). Apple devices do not support it.
If you are an audiophile and have to use Bluetooth headphones or earbuds, then LDAC is probably the best choice if your headphones and the playing device both support it.
Please refer to this guide about unleashing the power of LDAC Codec to enjoy Hi-Res Audio on Android Devices with WF-1000XM4, WF1000XM5, and WH-1000 series.
LHDC stands for Low Latency High-Definition Audio Codec. It is an audio codec technology developed by Savitech that allows high-resolution audio streaming over Bluetooth. It is a high-quality Bluetooth codec and allows a bit rate of up to 900 kbps (400/560/900kbps).
LHDC is designed to provide high-quality audio with low latency. It achieves this by using a proprietary algorithm that reduces the amount of data that needs to be transmitted. This algorithm also allows LHDC to adapt to different network conditions, ensuring that audio quality remains consistent even in situations where there is a lot of interference or congestion.
Although the LHDC codec was certified as one of the four Hi-Res Audio Wireless codecs, it is mainly supported by some Chinese manufacturers only. Android started to support LHDC from Android 10. Apple does not support it.
Samsung Seamless Codec (SSC)
Samsung Seamless Codec (SSC) is a proprietary technology, and Samsung does not publicly disclose some of the details of this codec. But its predecessor, Samsung Scalable Codec, can support a bit rate up to 512kbps. So, it is not surprising that Samsung Seamless Codec has a higher maximum bit rate.
Samsung also advertised this Bluetooth codec as a 24-bit Hi-Fi audio codec. But the performance of SSC has not been certified by any third-party organizations.
SCL6 is a new (6th generation) scalable audio codec developed by MQA, the company behind the MQA (Master Quality Authenticated) audio format. It is designed to provide high-quality audio over Bluetooth connections with low latency.
SCL6 offers a scalable and adaptable bit rate up to 960kbps. It was also certified as one of the four Hi-Res Audio Wireless codecs.
In addition to Bluetooth, SCL6 works with UWB (UltraWide Band) and Wi-Fi with a bit rate of up to 20mbps.
LC3plus is LC3's sibling with numerous additional functionalities and features aimed at Hi-Res audio. In the high-resolution mode, the maximum bit rate can reach up to 1000kbps for 24bit/96KHz. Unlike LC3, LC3plus is not free.
LC3plus is one of the four certified Hi-Res Audio Wireless codecs. However, device support is still rare because it is still new.
How to compare Bluetooth codecs for wireless headphones and earbuds?
The role of a Bluetooth codec is to compress the audio stream at the source in preparation for transmission and then decompress it at the receiving end for playback.
To compare different Bluetooth codecs for wireless headphones and earbuds, the following factors should be considered:
- Sample rate.
- Bit depth.
- Bit rate.
- Sound quality
Sample Rate (Hz)
Sample rate is the number of times an audio signal is sampled per second. The higher the sample rate, the more accurately the audio signal can be represented. To accurately represent any given frequency in a digital signal, at least two samples per cycle are required. This is why audio is typically sampled at a rate of 44.1kHz, which is approximately twice the upper limit of human hearing at 20kHz.
The sample rate for Bluetooth codecs typically ranges from 44.1 kHz to 96 kHz. CD-quality audio is 44.1 kHz, and high-resolution audio is typically 96 kHz.
The sample rate of a Bluetooth codec is important for audio quality. A higher sample rate will result in better audio quality, but it will also require more bandwidth.
Here is a table of sample rates for common Bluetooth codecs:
|SBC||44.1 kHz, 48 kHz|
|AAC||8 kHz to 44.1 kHz|
|LC3||8, 16, 24, 32, 44.1, 48, 96 kHz|
|aptX HD||44.1 kHz, 48 kHz|
|aptX Adaptive||25.6 kHz to 48 kHz|
|LDAC||44.1 kHz, 48 kHz, 88.2 kHz, 96 kHz|
|LHDC||44.1 kHz to 96 kHz|
|SSC||44.1kHz, 48 kHz|
|SCL6||44.1 kHz, 48 kHz, 88.2 kHz, 96 kHz|
|LC3Plus||44.1 kHz, 48 kHz, 88.2 kHz, 96 kHz|
Bit Depth (bits)
The bit depth of a Bluetooth codec refers to the number of digital bits used to represent each sample (remember the sample rate) of the audio data. You can also interpret the bit depth as the number of levels between the quietest and the loudest frequency of any samples. 16-bit means 65,536 levels.
A higher bit depth means more precision in the representation of the audio signal in one sample, which usually leads to better sound quality.
The most common bit depths used for Bluetooth codecs are 16 and 24 bits. 16-bit audio is the standard found on CDs, which is generally considered to be good enough for most people's listening needs. However, if you're looking for a more detailed and nuanced sound, 24-bit audio is considered to be high-resolution audio, which can provide just that.
Here is the bit depth of the commonly used Bluetooth codecs for headphones and earbuds:
|LC3||16-bit, 24-bit, 32-bit|
|aptX Adaptive||16-bit, 24-bit|
|LC3Plus||16-bit, 24-bit, 32-bit|
Bit Rate (kbps)
The bit rate refers to the amount of data that can be transferred per second by a Bluetooth codec. It is measured in kilobits per second (kbps) or megabits per second (Mbps). A higher bit rate indicates that more data can be transferred, which in turn can lead to improved sound quality.
Most Bluetooth codecs have a set maximum bit rate, but the actual bit rate utilized depends on two factors – the available bandwidth and the quality of the audio source. In the case of low bandwidth, the bit rate will decrease to prevent audio dropouts. Likewise, when the audio source is of low quality, using a high bit rate is unnecessary.
The maximum bit rate of some Bluetooth codecs is summarized in the table below.
|aptX HD||576 kbps|
|aptX Adaptive||420 kbps|
|SSC||> 512 kbps|
When it comes to evaluating sound quality, there is no one-size-fits-all answer. Sound quality is subjective, varying from person to person based on individual preferences and experiences. What one person may perceive as excellent sound quality, another might find lacking or unimpressive. Some people might prioritize clarity and precision, while others might prefer warmer or more bass-heavy tones.
Bluetooth codecs affect sound quality significantly. Generally, codecs that have higher bit rates and more advanced compression algorithms tend to produce better sound quality. However, it is worth noting that the quality of the Bluetooth connection and the source material can also play a role in the overall sound quality.
Here is the rough evaluation of the sound quality performance of various Bluetooth codecs, assuming Hi-Res music source, strong Bluetooth connections, and high-end headphones with proper codec support.
|LC3||No Devices to Test|
|aptX HD||Very Good|
|aptX Adaptive||Very Good|
|SCL6||No Devices to Test|
|LC3Plus||No Devices to Test|
Latency is the time delay between when an audio signal is sent from a source device to a Bluetooth receiver and when it is actually heard. Latency is a common issue with Bluetooth audio, and it can be particularly noticeable when watching videos or playing games.
The latency of a Bluetooth codec is determined by a number of factors, including the codec itself, the bitrate, and the quality of the Bluetooth connection. In general, codecs with lower bitrates and more advanced compression algorithms tend to have lower latency.
If you are a gamer or a video watcher, you might want to choose a codec that minimizes the delay between the audio and the video. aptX, aptX LL, and SBC are generally considered to offer lower latency than LDAC, aptX HD, and LHDC.
What is the proper way to consider Bluetooth codec when buying new wireless headphones and earbuds?
Among all Bluetooth codecs, only SBC (and LC3 for LE audio) is mandatory. However, other codecs are not universally supported and are only available on certain devices. If you want to utilize a Bluetooth codec other than SBC, you must make sure that both the transmitting device (such as your Android phone or iPhone) and the receiving device (for instance, wireless headphones or earbuds) support the same codec.
Understanding the Bluetooth codec can help you get the right wireless headphone or earbuds.
You need to consider the following factors:
- Your sending device.
- Your intended usage scenario.
Your sending device
If you have multiple devices or use different platforms, you might want to choose a codec that is widely supported by most devices. Second to the mandatory SBC codec, AAC is widely supported on most devices and platforms, for example, Android, iOS, Mac, Windows, and Linux.
For Android users, LDAC is supported on Android devices with Android Oreo or later. LHDC is supported on Android 10 or later. LC3 codec is supported in Android 13 or later. Of course, a few Android manufacturers may disable the support due to hardware limitations.
Support for aptX family codecs is very complicated on Android devices. Android supports aptX since Android Oreo. But unlike LDAC or LHDC, aptX family codecs require licensing fees from hardware manufacturers for the decoder. Therefore, some Android devices actually do not support aptX family codecs. You need to check the device specification to see whether it supports aptX codecs and which aptX codecs are supported.
Bluetooth codec support on Windows is messy. Officially, only SBC and AAC are supported on Windows 10/11. However, if your PC or laptop has a compatible Bluetooth chipset (usually integrated with WiFi), LDAC and aptX codecs may also work.
Your intended usage scenario
If you are gaming or watching videos, you want to use a codec that minimizes the latency and avoids audio-video sync issues, such as aptX, aptX Low Latency, or LC3.
If you are listening to podcasts or audiobooks or Spotify, you can use a codec that maximizes the battery life and doesn't affect the voice quality much. SBC or AAC is usually sufficient.
However, if you want to enjoy high-fidelity music (e.g., playing FLAC music files), you may consider LDAC, aptX HD, aptX adaptive, or LHDC.
Normally, the more expensive flag-ship wireless headphones or earbuds support more advanced codecs. The budget product line usually supports SBC and AAC only.
Please note Bose traditionally only supports SBC and AAC codecs, even on the flagship products. However, in the latest lineup, QuietComfort Ultra Headphones and QuietComfort Ultra Earbuds finally support aptX adaptive codec.
All Apple headphone/earbuds products (AirPods, AirPods Pro, and AirPods Max) only support SBC and AAC codecs.
Sony always includes LDAC support on all generations of the WH-1000 series. Among the earbuds, LDAC support can be found on the WF-1000-xm4, WF-1000xm5, and LinkBuds S. Sony usually markets these products as “premium” headphones/earbuds.
Wireless Headphones and earbuds from Bang & Olufsen, Bowers & Wilkins, Sennheiser, Jabra, and Shure often support aptX codecs. Qualcomm maintains a list of aptX-enabled products here.
Do you have any questions about Bluetooth Codec for wireless headphones and earbuds?
If you have any questions about the Bluetooth codec for wireless headphones and earbuds, or if you want to share your thoughts or experiences with Bluetooth codecs, please post them in the comment box below.
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