What Are Bluetooth Codecs? A Bluetooth codec is a software format that compresses and encodes music, making it efficiently transmissible wirelessly between devices. These codecs determine how Bluetooth audio is transmitted from the source device (e.g., smartphone or tablet) to the Bluetooth speaker or headphones. The term “codec” comes from the process of encoding and decoding the transferred media.
There are four most popular Bluetooth codecs, namely: SBC (developed by the Bluetooth Special Interest group – SIG), AAC (developed by the Moving Picture Experts group – MPEG), aptX (developed by Qualcomm), and LDAC (developed by Sony).
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Why Should You Care?
- The choice of Bluetooth codec significantly affects sound quality between your source device and audio peripherals (headphones, speakers, etc.).
- Different codecs have varying bitrates and methods of processing data during transmission.
- If you want the best possible audio quality over Bluetooth, consider using a higher-quality codec than the standard AAC and SBC ones; I advice that you preferably go with an aptX codec.
- Understanding and selecting the right codec ensures an optimal listening experience when using Bluetooth devices.
Introducing the top Bluetooth codecs
SBC (Sub-band Coding): SBC is an audio subband codec specified by the Bluetooth Special Interest Group (SIG) for the Advanced Audio Distribution Profile (A2DP). It serves as a digital audio encoder and decoder used to transfer data to Bluetooth audio output devices like headphones or loudspeakers.
- Key Points:
- Basic codec with the lowest bit rate.
- Provides manageable transfer rates (192-320 kbps) at the expense of sound quality.
- Mandatory for all A2DP-enabled devices, making it virtually universal.
- SBC is the most widely used Bluetooth codec, being supported by most Bluetooth gadgets and devices.
AAC (Advanced Audio Codec): AAC is a widely supported Bluetooth codec used by Apple. It provides fairly good audio quality without requiring excessive processing power. AAC has a maximum transfer rate of 250 kbps and can support audio quality up to 24-bit/96 kHz.
- Key Points:
- Preferred by Apple.
- Inconsistent when used with Android devices.
- Offers higher audio quality than SBC.
aptX: aptX is a series of Bluetooth codecs developed by Qualcomm as an alternative to SBC with the objective of matching the audio quality of wired headsets. It can transmit audio at CD-like 16-bit/44.1 kHz and has a data rate of 352 kbps. aptX is found in various devices, including computers, smartphones, and consumer electronics products.
- Key Points:
- Widely used and synonymous with Bluetooth.
- Provides good audio quality.
- Supports higher bit depth and sampling rate than SBC.
- Found only in smartphones using Qualcomm chipsets (for now).
aptX codecs include: standard aptX, aptX HD, aptX Adaptive, and Snapdragon Sound. Click on each name to go read up some more about their specifics.
LDAC: LDAC is a proprietary audio coding technology developed by Sony. It allows streaming high-resolution audio over Bluetooth connections at up to 990 kbps and 32 bits/96 kHz. LDAC is used in headphones, earphones, smartphones, and other devices.
- Key Points:
- Handles hi-res audio efficiently.
- Approximately three times more data can be streamed over Bluetooth compared to other codecs.
- Offers impressive quality on paper, but real-life performance may vary.
Comparison: SBC vs AAC vs aptX vs LDAC
- SBC: Basic, universal, and manageable transfer rates.
- AAC: Preferred by Apple, better quality than SBC.
- aptX: Widely used, good audio quality, and higher bit depth.
- LDAC: High-resolution audio, efficient streaming, and impressive specifications.
Choosing the right codec depends on your device compatibility and desired audio quality. Personally, I am a fan and evangelist of aptX codecs and look out for that in devices that I am interested in. What is limiting the adoption of aptX codecs is that fewer smartphones are using Qualcomm chipsets, thanks to the rise of MediaTek and other chip brands. As such, where my devices do not support aptX, I gladly use Bluetooth accessories that support SBC, as it is the most widely available Bluetooth codec right now. It is the most basic codec, but where the desirable is not available, the available becomes desirable.
If you are an Apple device user, you are pretty much tied to AAC, as that is what Apple has stuck with, at least for now.