Codecs
When you have a Bluetooth headphone connected to your phone, digital audio data transmitted over Bluetooth from your phone to your headphones is encoded and decoded, so called codec (codec is short for coder/decoder) - a specified format. Each code determines how audio data is transferred (encoded and decoded) over Bluetooth.
In terms of fidelity, the LDAC codec is the best, but it's not very good for latency, stability and battery life (it drains battery faster than other codec). LC3 replaced the AptX-LL for the lowest latency but it's varied between devices and how it is implemented.
AAC and SBC don't sound as good as LDAC, but it drains Bluetooth accessories' battery slower.
Note that Bit Depth, Sampling Rate and Bit Rate are three critical parameters.
Codec | Logo | Bit Depth | Sampling Rate | Max Sample Rate | Max Bitrate | Introduced | Audio latency |
---|---|---|---|---|---|---|---|
aptX | ![]() |
16 bit | 44.1 kHz, 48 kHz | 48.0 kHz | 352 kbps | 2009 | ~ 40-70 ms |
aptX HD | ![]() |
24 bit | 44.1kHz, 48kHz | 48.0 kHz | 576 kbps | 2016 | ~ 250-400 ms |
aptX LL | ![]() |
16 bit | 44.1 kHz, 48 kHz | 44.1 kHz | 352 kbps | 2016 | ~ 30-40 ms |
AAC | ![]() |
24 bit | Between 8 kHz and 96 kHz | 96.0 kHz | 264 kbps | 2015 | ~ 100-400 ms |
SBC | ![]() |
16 bit | 16 kHz, 32 kHz, 44.1 kHz, 48 kHz | 48.0 kHz | 320 kbps | 2003 | ~ 200-300 ms |
aptX Adaptive | ![]() |
16/24 bit | 44.1 kHz, 48 kHz, 96 kHz | 48 kHz | 420 kbps | 2018 | ~ 40-90 ms |
LHDC | ![]() |
24 bit | 44.1 kHz, 48 kHz | 96 kHz | 990 kbps | 2019 | |
LLAC | 24 bit | 48 kHz | 600 kbps | ~ 30-120 ms | |||
LDAC | ![]() |
24 bit | 44.1 kHz, 48 kHz, 96 kHz | 96.0 kHz | 990 kbps | 2015 | ~ 200-400 ms |
UAT | ![]() |
24 bit | Up to 192kHz | 192 kHz | 1.2 Mbps | 2019 | |
SSC | ![]() |
24 bit | 44.1kHz, 48 kHz | 96 kHz | 512 kbps | 2019 | |
Airoha's Hi-resolution codec | 24 bit | 192 kHz | |||||
AptX Lossless | ![]() |
16 bit | 44.1 kHz | 1 Mbps | 2021 | ||
AAC-ELD | 96 kbps | ||||||
LC3 | 16/24/32 bit | 8 kHz, 16 kHz, 24 kHz, 32 kHz, 44.1 kHz, and 48 kHz | 48 kHz | 345 kbps | 2020 | ~ 20-30 ms | |
Atpx Voice | 32kHz | 32 kHz | 2020 | ||||
FastStream | 16 | 48 kHz | 212 kbps | ~ 30-40 ms | |||
L2HC | 24 bit | From 8 kHz to 96 kHz | 96 kHz | 960 kbps | 2023 | ~ 5-10 ms |