If you’ve shopped for or have been looking for any wireless headphones or speakers, you might have seen mention of aptX.
But what’s aptX?
aptX is an audio-coding algorithm created in the 1980s by Qualcomm. It’s popular with film studios and radio broadcasters. And these days it is synonymous with Bluetooth.
As defined on its official website:
“aptX is a proven technology that compresses and then decompresses audio as it travels from a source device like a phone, to a receiving device like a wireless speaker, in a way that it can be transmitted over Bluetooth without damaging the quality. This ensures that you get the very most from your audio.”
aptX promises to deliver CD-like sound quality over Bluetooth. But it’s not CD-quality and does not sound as good as audio transmitted over wired connections. So you will generally find the wireless earbuds, headphones, speakers may not sound as good as wired ones.
Why does that happen?
Because Bluetooth is definitely depressed to help reduce audio coding delays and minimizes latency issues. However, with a compression ratio of 4:1, bitrate of 384kbps (48Hz sampling), aptX is designed to sound better than standard Bluetooth.
How much does aptX help improve sound quality?
To understand how aptX works. Let’s talk about digital audio and Bluetooth firstly.
Digital audio is a technology that records or convert sounds in digital form. In digital audio, the sound wave of the audio signal is encoded as numerical samples in a continuous sequence. For example, in CD audio, samples are taken 44100 times per second each with 16-bit sample depth.
Bluetooth a low power wireless transmission method and music is transmitted using a high-quality audio A2DP transmission profile. And the profile standardizes one mandatory codec – SBC, which stands for Low Complexity Subband Coding. As there are multiple levels of SBC, the lowest common denominator wins when you transmit data between two devices. For example, if your phone can do SBC at a high rate, but your headphones can’t, you get whatever the maximum rate the headphones can handle, and vice versa.
And comes to aptX, it is still compression, but a different kind. While MP3 uses the psychoacoustic modeling to take out data, aptX uses "time-domain ADPCM”. With the aptX audio codec technology, the source material is transparently delivered over Bluetooth, whether it is stored uncompressed or in a compressed format such as MP3, AAC, FLAC.
But one important thing is, you must have the aptX on both the phone and headphones to get the advantage of aptX technology. If only one has it, the other just run SBC. The aptX encoding is supported on Android 4.4+, Windows 10 (desktop and mobile), macOS, to name a few. Unfortunately, you will not be able to get the advantage of aptX if you use an iPhone.
Would you like to get an aptX enabled wireless earbuds? Take a look at our latest B530 Pro true wireless earbuds.