Bluetooth audio transmission always involves some form of compression. The exact amount of compression varies significantly depending on the specific Bluetooth audio codec being used by your devices (headphones, speakers, phone, computer, etc.).
Bluetooth Bitrates and Compression Levels
Audio compression for Bluetooth is typically measured by the bitrate, which is the amount of data transmitted per second, usually in kilobits per second (kbps). A higher bitrate generally means less compression and potentially better audio quality, while a lower bitrate means more compression and a smaller data stream.
The provided reference highlights various common Bluetooth codecs and their typical bitrates:
Common Bluetooth Audio Codecs and Bitrates
| Bluetooth Codec | Typical Bitrate (as per reference) | Compression Level |
|---|---|---|
| SBC (Subband Coding) | As low as 256 kbps | High compression |
| AAC (Advanced Audio Coding) | As low as 256 kbps | High compression |
| aptX | Around 600 kbps | Moderate compression |
| LDAC | Around 900 kbps | Lower compression |
| SSC (Samsung Seamless Codec) | Around 900 kbps | Lower compression |
| aptX Lossless | Around 1600 kbps | Designed for lossless (CD quality or better) |
Note: These bitrates can sometimes vary depending on the specific implementation and connection quality.
Understanding the Compression
Compared to uncompressed CD-quality audio, which has a bitrate of approximately 1411.2 kbps (16-bit, 44.1 kHz stereo), you can see the different levels of compression:
- High Compression: Codecs like SBC and AAC operating around 256 kbps significantly compress the audio data. This is often done to ensure a stable connection, but it removes more audio information.
- Moderate to Lower Compression: Codecs such as aptX, LDAC, and SSC offer higher bitrates (600-900 kbps), reducing the amount of compression compared to SBC or AAC, leading to potentially better fidelity.
- Lossless/Near-Lossless: aptX Lossless, with a bitrate of around 1600 kbps, is designed for "lossless CD transmission." This means it aims to transmit audio data at a quality equivalent to or better than the original CD source without discarding information.
Therefore, the degree of compression varies widely, from significant compression with basic codecs at lower bitrates to near-lossless transmission with advanced codecs designed for higher fidelity.
