When you purchase Bluetooth headphones, earbuds, or a Bluetooth speaker, you are also selecting the Bluetooth codec that will be used for connection. Codecs compress audio signals for efficient transmission and decompress them for playback.
Not all codecs are equal. The choice of codec is crucial due to Bluetooth’s limited bandwidth. Qualcomm’s industry-leading “aptX” codecs come in five different versions, each offering varying levels of performance to enhance sound quality, reduce latency, and more.
If you’re confused, don’t worry. We are here to help you understand aptX so you can make informed decisions when buying audio products.
What is aptX?
Bluetooth codecs are necessary to compress audio for transmission due to Bluetooth’s narrow wireless pipe. SBC has been the default codec since 2003. AptX, acquired by Qualcomm in 2015, offers higher-quality audio and lower latency than SBC.
The compatibility problem
Alternative codecs like aptX require support on both the source and sink devices for them to work. While aptX is commonly supported across Android devices, Apple typically only supports AAC on its iOS devices.
Are aptX’s benefits real?
AptX offers improved sound quality over SBC and AAC due to its different form of lossy compression and fixed data rate of 352 Kbps. This makes it better at preserving details in heavily compressed audio files.
AptX Low Latency
AptX LL reduces latency to about 38 milliseconds, making it ideal for gaming and syncing video and audio. However, few smartphones support aptX LL, making it challenging to leverage this feature.
AptX HD
AptX HD supports higher quality audio at up to 24-bit/48kHz with a fixed data rate of 576 Kbps. It is backward compatible with classic aptX, although it may face connectivity issues on true wireless earbuds.
AptX Adaptive
AptX Adaptive adjusts its data rate from 110 Kbps to 620 Kbps based on link conditions, offering up to 24-bit/96kHz resolution. It’s more efficient than aptX HD and can switch to low-latency mode for gaming.
AptX Lossless
AptX Lossless delivers CD-quality audio at 16-bit/44.1kHz, promising bit-for-bit perfect audio. It requires Qualcomm’s Snapdragon Sound certification for devices to support this feature.
How do you know if you’re getting aptX’s speed benefits?
Tracking the performance of advanced codecs like aptX can be challenging due to the lack of tools in most devices. Qualcomm’s Snapdragon Sound certification ensures that specific aptX Adaptive features work seamlessly between compatible devices.
Snapdragon Sound
Snapdragon Sound certification guarantees compatibility with specific aptX Adaptive features and performance testing. However, feature support can vary among devices, so buyers should research before making a purchase.
