SBC vs. aptX: Bluetooth Codec Comparison

This article delves into the comparison between two common Bluetooth audio codecs: SBC and aptX. We’ll explore their features and highlight the key differences relevant to Bluetooth audio quality and performance.

Introduction to Bluetooth

Bluetooth is a ubiquitous short-range wireless technology operating in the 2.4 GHz ISM band. It boasts a range spanning approximately 10 to 100 meters, making it ideal for connecting devices in close proximity.

Bluetooth comes in various flavors, including Bluetooth Classic, Bluetooth Low Energy (BLE), and Bluetooth High Speed. It utilizes different profiles tailored to specific applications. Some popular profiles include:

• Hands-Free Profile (HFP): For hands-free calling.
• Headset Profile (HSP): For basic headset functionality.
• A2DP (Advanced Audio Distribution Profile): For streaming high-quality audio.
• A/V Remote Control Profile (AVRCP): For controlling audio/video playback remotely.
• Phone Book Access Profile (PBAP): For accessing phone book data.
• Message Access Profile (MAP): For accessing messages.

These profiles leverage various audio codecs to encode and decode audio data, with aptX, SBC, mSBC, and AAC being among the most prevalent.

SBC Audio Codec

SBC, short for Sub Band Coding, is a standard Bluetooth audio codec with the following characteristics:

• It offers reasonably good audio quality at medium bit rates while maintaining low computational complexity, making it efficient.
• It’s the mandatory codec for the A2DP profile as specified by the Bluetooth Special Interest Group (SIG). This means all A2DP devices must support SBC.
• It acts as a digital audio encoder and decoder.
• It’s used to transmit audio data to Bluetooth output devices like headphones and speakers.
• SBC supports both mono and stereo streams.
• It supports sampling frequencies up to 48 kHz.
• It supports bit rates up to 198 Kbps (mono stream) and up to 345 Kbps (stereo stream).
• It uses either 4 or 8 sub-bands and employs an adaptive bit allocation algorithm along with adaptive block PCM quantizers for efficient audio encoding.
• It’s utilized by A2DP profile version 1.3.

aptX Audio Codec

aptX is another popular Bluetooth audio codec with the following attributes:

• It’s developed by Qualcomm.
• It’s generally considered to provide higher audio quality compared to the SBC codec.
• It’s implemented in numerous Android platforms, such as the Samsung Galaxy S series, as well as Apple’s OSX.
• It’s employed in both consumer and automotive wireless audio applications, such as real-time audio streaming over Bluetooth A2DP between source and sink devices.
• aptX utilizes a time-domain ADPCM (Adaptive Differential Pulse Code Modulation) technique for audio encoding.