Bluetooth Codec
Last updated
Last updated
The graph above illustrates the relationship between Bluetooth codec types, bitrates, and sound quality.
Y-axis (vertical): Represents sound quality, where a higher position indicates better quality.
X-axis (horizontal): Represents bitrate, with higher values toward the right indicating higher bitrates.
SBC was chosen as the default codec during the early stages of Bluetooth audio development.
It offers the lowest audio performance among the codecs.
The primary reason for its selection as the default codec was its simple implementation and low computational requirements, which aligned with the semiconductor and battery technologies of decades ago.
Known for delivering the best sound quality relative to bitrate.
AAC is the only codec listed here based on a Psychoacoustic Model.
Instead of directly encoding the waveform, it analyzes in real-time which parts of the audio are audible to humans and which are not.
It allocates more precision (bits) to audible parts and fewer bits to masked or inaudible parts.
Due to this model, AAC does not allow traditional measurements like THD or SNR; its performance is evaluated purely by human perception (Perceptual Sound Quality).
It requires significant algorithmic complexity and computational power.
For example, iPhones operate AAC at 260 kbps.
Developed with a focus on high bitrate and high sound quality.
Unlike SBC and aptX, which encode directly in the Time Domain, LDAC converts data into the Frequency Domain for encoding.
This results in higher complexity and efficiency than SBC and aptX but lower than AAC.
LDAC is recommended for Android devices. Generally, LDAC at 660 kbps or higher provides sound quality nearly indistinguishable from wired audio. *There have been occasional reports of sound quality degradation with LDAC. Please check the bitrate when this occurs.
Q: Does the sound quality differ when connecting and playing via Bluetooth LDAC on Android devices like Samsung or LG (Quad DAC)?
A: No, it does not. When listening to music through a Bluetooth receiver like the Qudelix-5K, the DAC/AMP built into the receiver performs all the analog conversions. The source device encodes (compresses) the digital audio into LDAC and transmits it to the receiver. Since the same SONY LDAC encoder is used, source devices have no difference in sound quality.
However, some people report sound quality differences with LDAC on certain smartphones. It is often due to audio effects like Dolby or other settings enabled on the smartphone.
Additionally, some smartphone models may face Bluetooth RF performance issues, preventing them from reaching LDAC's full 990 kbps bitrate, which can cause discrepancies in sound quality.