What bitrate is Bluetooth audio?
Bitrate refers to the amount of data transferred per second for digital audio transmission via Bluetooth. It determines the quality and fidelity of Bluetooth audio playback. Higher bitrates allow for transfer of more data and higher audio sample rates, resulting in better sound quality.
Bluetooth audio works by encoding the audio data and transmitting it between devices over Bluetooth connections. Different Bluetooth codecs use different bitrates, sample rates, and compression methods to encode the audio.
The purpose of varying bitrates in Bluetooth audio is to balance audio quality with stable connectivity. Lower bitrates allow for more reliable connections but result in lower quality. Higher bitrates enable transfer of CD-like quality audio but may falter if the Bluetooth connection is unstable.
Standard Bluetooth Bitrates
The standard bitrates for Bluetooth audio are:
- SBC: Max 328 kbps, typically around 250 kbps
- AAC: Max 328 kbps, typically around 250 kbps
- aptX: 352 kbps
- aptX HD: 576 kbps
- LDAC: Max 990 kbps, with quality levels of 330/660/990 kbps
The SBC and AAC codecs are mandatory for all Bluetooth devices. SBC is the most basic Bluetooth audio codec that all devices must support. It has a max bitrate of 328 kbps but is typically around 250 kbps. AAC is also widely supported and offers improved audio quality over SBC. However, it has the same max bitrate as SBC.
The aptX codec offers improved audio quality and lower latency compared to SBC/AAC. It has a bitrate of 352 kbps. aptX HD further builds on this with support for 24-bit audio and a higher 576 kbps bitrate. This allows for near CD-quality wireless audio.
LDAC is an advanced codec developed by Sony that can reach up to 990 kbps bitrate. It provides high-resolution wireless audio that can rival wired connections. LDAC has three quality levels of 330 kbps, 660 kbps, and 990 kbps. The higher the bitrate, the better the audio quality.
In summary, the different codecs each provide progressively better audio quality and lower latency. SBC/AAC provide basic playback while aptX HD and LDAC allow for high-fidelity wireless audio comparable to CDs and lossless formats.
SBC Codec
SBC (Subband Coding) is the default Bluetooth audio codec included in the Bluetooth specification. SBC uses a compression algorithm to reduce the size of the audio for transmission over Bluetooth.
The SBC codec supports bitrates ranging from 192kbps to 345kbps. The maximum bitrate for mono audio is 345kbps, while stereo audio is limited to 328kbps. Lower bitrates like 192kbps or 220kbps are commonly used to reduce bandwidth requirements. However, lower bitrates also negatively impact sound quality and audio fidelity.
At its highest bitrate of 328kbps, the SBC codec provides reasonably good sound quality that approaches CD quality audio. However, the compression algorithm introduces some audible artifacts, noise, and loss of clarity compared to the original source audio. The sound quality degrades noticeably as the bitrate drops below 260kbps.
Overall, the SBC codec provides only basic Bluetooth audio quality. While acceptable for background listening and Bluetooth speakers, it does not deliver audiophile quality sound compared to more advanced codecs like aptX and LDAC. The lower latency of SBC can be beneficial for videos and gaming.
AAC Codec
AAC (Advanced Audio Coding) is a lossy compression codec developed by Dolby that is commonly supported by Apple devices. It is designed to achieve better sound quality than SBC at similar bitrates [1].
The AAC codec supports bitrates up to 250 kbps, though the specific bitrate can vary depending on the Bluetooth transmitter and receiver. At its highest bitrates, AAC provides noticeably better audio quality compared to SBC, with richer sound and better handling of high frequencies [2].
However, AAC has some downsides. Lower bitrate AAC can sound significantly worse than SBC, so bitrate must be sufficiently high to get the full benefit. Additionally, AAC compatibility and performance is inconsistent on Android devices compared to Apple devices [2]. Overall, AAC provides good sound quality for Apple users when properly implemented.
aptX Codec
The aptX codec was developed by Qualcomm and is designed to improve audio quality over standard Bluetooth connections. aptX uses a bit rate of 352kbps and samples audio at 44.1kHz [1]. This provides CD-like audio quality that is superior to the default SBC codec used by Bluetooth.
One key feature of aptX is its low audio coding latency of around 40ms. This results in more synchronized audio that better matches the video or gameplay its paired with. The higher bit rate also allows aptX to encode a wider frequency range and dynamics compared to SBC [3].
However, the higher 352kbps bit rate means aptX uses more bandwidth and power compared to SBC. So there is a tradeoff between improved audio quality and battery life. aptX also does not reach the fidelity of wired connections or more advanced codecs like LDAC.
LDAC Codec
LDAC is a high-resolution Bluetooth audio codec developed by Sony that can transmit audio at up to 990 kbps. It uses lossy compression to transmit hi-res audio over Bluetooth wireless connections. LDAC works by splitting the hi-res audio signal into packets and transmitting them individually over Bluetooth. The three selectable bitrates for LDAC are:
- 330kbps: Provides stable connectivity in noisy environments but lower audio quality.
- 660kbps: Balances audio quality and connectivity.
- 990kbps: Highest audio quality but may be prone to connectivity issues.
At 990kbps, LDAC can transmit 24 bit/96 kHz hi-res audio files completely uncompressed. Lower bitrates use lossy compression, so there is some loss in audio quality. However, LDAC at 660kbps still provides excellent CD-like audio quality. The main tradeoff with LDAC is connectivity strength versus maximum audio quality. At the highest 990kbps bitrate, small hiccups in the Bluetooth connection can cause audio dropout. Choosing a lower bitrate provides a more stable connection but at the cost of lower audio resolution.
Choosing a Bitrate
When choosing a Bluetooth audio bitrate, there are a few key factors to consider:
First, think about your use case. If you’re listening to music casually in the background, a lower bitrate like SBC’s 328kbps may suffice. However, for critical listening like mixing audio or gaming where lag is detrimental, you’ll want a higher bitrate codec like LDAC’s maximum 990kbps.
You’ll also need to balance audio quality and bandwidth. Higher bitrates mean more data transferred per second, which translates to better quality. But they also consume more bandwidth. If you’re in an area with lots of wireless interference, connections can become unstable at very high bitrates.
Finally, consider your source audio quality. There’s no benefit to high bitrate codecs if you’re streaming low quality audio. Match the bitrate to the quality of your audio source.
In most cases, 320-600kbps provides a good blend of quality and reliable connectivity for Bluetooth audio streaming. Test different bitrates to see what works best for your listening situation.
Setting the Bitrate
The default bitrate used by Bluetooth audio depends on the Bluetooth codec being utilized. The most commonly used Bluetooth codec for audio is SBC, which has a default bitrate of 328kbps. Other codecs like AAC, aptX, and LDAC have higher default bitrates – for example, LDAC defaults to 990kbps.
You can change the bitrate settings on both Android and iOS devices, though the process differs between operating systems.
On Android, open the Settings app, go to Developer Options, and select “Bluetooth Audio Codec.” Here you can choose your preferred codec like AAC or aptX as well as adjust the bitrate. For example, with LDAC you can set the bitrate to 990kbps (best quality), 660kbps (balanced) or 330kbps (best connection). The optimal setting depends on your listening needs and environment.[1]
On iOS, go to Settings, Bluetooth, tap the “i” next to your headphones, and choose your preferred codec. The bitrate cannot be adjusted beyond each codec’s default. For example, AAC will use a bitrate of 250kbps and there’s no setting to change this.[2]
On both platforms, changing to a higher quality codec like aptX or LDAC can provide better sound quality. However, the headphones must also support the codec in order to utilize it. Always check for codec compatibility. Higher bitrates require more bandwidth and may be prone to connectivity issues, so balance audio quality needs with your environment.
[1] https://www.makeuseof.com/change-bluetooth-codec-android/
[2] https://www.soundguys.com/bluetooth-codec-support-headphones-61989/
Troubleshooting Bluetooth Audio Quality
If you experience issues with Bluetooth audio quality like skipping, static, echoes or disconnects, there are a few steps you can take to troubleshoot:
First, check your device connections and make sure your Bluetooth source device and receiving device are both powered on and paired properly. Try disconnecting and re-pairing the devices if the connection seems faulty. Also ensure the devices are within range – 30 feet or less for most Bluetooth versions.
Interference from other wireless devices can also impact Bluetooth audio. Make sure WiFi, routers, microwaves and other appliances are not active or located too closely to your Bluetooth source and receiving device.
On Windows 10 and 11 PCs, you can try adjusting the Bluetooth sample rate in Sound Settings to CD quality or lower, as very high sample rates can cause choppy audio over Bluetooth. See this Microsoft Forum post for details.
Updating your device’s Bluetooth drivers can also help resolve connectivity and audio issues. Check your device manufacturer’s website for the latest drivers. On Windows, you can update drivers automatically via Device Manager.
As a last resort, resetting network settings on your Bluetooth source and receiving devices can remove any faulty configurations that may be disrupting the Bluetooth connection. Just be aware this resets all wireless settings, not just Bluetooth.
If you continue having Bluetooth audio quality problems after trying these troubleshooting tips, consult your device manuals or contact technical support for further assistance.
Conclusion
In summary, standard Bluetooth audio has a bitrate of 328 kbps using the SBC codec. Higher quality codecs like AAC, aptX, and LDAC can achieve bitrates between 250 kbps to 990 kbps. The bitrate determines audio quality, with higher bitrates delivering better quality. When choosing headphones, look for support for advanced codecs beyond basic SBC. You can usually adjust the bitrate in your device’s Bluetooth settings to balance quality and latency. Some troubleshooting steps for low quality Bluetooth audio include checking codec support, increasing the bitrate, and minimizing interference.
In the future, we will likely see more adoption of high bitrate codecs like aptX HD and LDAC for enhanced quality. Bluetooth specifications will continue improving to allow for lossless CD-quality wireless audio. As Bluetooth audio becomes more prevalent, bitrates will steadily rise to keep pace with listener’s expectations.
Bluetooth audio has come a long way in a relatively short time. We’ve gone from struggling with frequent dropouts to enjoying high definition wireless audio. Yet there remains room for improvement when it comes to latency and truly lossless quality. While the bitrates continue increasing, audiophiles eagerly await the day Bluetooth can fully match and exceed the fidelity of wired listening.