What is Bluetooth
Bluetooth is a wireless technology standard for exchanging data over short distances from fixed and mobile devices, and building personal area networks. This technology is slowly infiltrating the wireless headphone market these days. Bluetooth was introduced in the 1990s and was intended as a wireless replacement for the serial ports used to connect printers, mice and other peripherals to personal computers. The Bluetooth specifications for a smartphone, often have something like “A2DP, AVRCP, HFP, HID, HOGP, HSP, PBAP or aptX.” These acronyms refer to different Bluetooth Profiles. They cover everything from allowing the radio in your car to access your personal phone book, to synchronizing the volume of your smartphone and connected Bluetooth audio devices. Let’s particularly look at the A2DP profile since it enables stereo headphones with wireless Bluetooth connectivity.
What is A2DP
A2DP stands for Advanced Audio Distribution Profile. After the addition of A2DP, Bluetooth became a major player in the music market. However, at introduction to the market, A2DP had a horrible sound quality. It works by taking a big portion of the bandwidth dedicated to two-way communications in a Bluetooth connection and turning it into a one-way transmission for music. That larger transmission allows for higher-quality headphone audio. The more data you send across a Bluetooth connection, the more battery power it takes on both the sending and receiving end. And the whole point of Bluetooth is to use as little bandwidth and power as possible to accomplish a task. To keep your smartphone’s and headphones’ battery from draining very fast, the music on your smartphone is compressed before being sent down that A2DP transmission. By default, A2DP relies on a codec called SBC, or Low Complexity Subband Coding, to compress the music being delivered to your headphones. A2DP can support more advanced codecs for packing your music on one end and unpacking it at the other. One of those advanced codecs is aptX. The downside of SBC is that it can have poor sound quality in its lower-bandwidth implementations. This explains Bluetooth’s early reputation for bad audio quality. That reputation is however changing due to aptX. Related Article: How Bluetooth pairing with NFC works
Aptx explained
AptX is one of the A2DP-supported codecs, meaning that it’s a set of instructions for how to code and decode data that Bluetooth transmits. IT was created in the 1980s and originally used in radio broadcasting and commercial movie theaters. The aptX codec is practically synonymous with high-fidelity Bluetooth audio, for several reasons. To begin with, aptX works differently from other codecs used by A2DP. It doesn’t rely on “psycho-acoustics” to remove the bits of your music that you aren’t likely to hear, but works by measuring the differences between one moment in time and the next, and transmitting those differences. AptX is good at compressing and decompressing your music, and is less of a drain on your battery. It also introduces less delay than other codecs making it handy if you wear wireless headphones while watching videos or playing games on your mobile device. With other codecs, Bluetooth audio can be out of sync with your video by 800 ms or 8/10’s of a second or more. AptX reduces that delay to as little as 60ms or 30ms in its Low Latency version. With aptX, your video and audio will be more in sync. With aptX, you won’t have to dig through esoteric specification boxes or a list of alpha-numerics to find out if your devices support it. Since aptX is a licensed technology, manufacturers usually indicate aptX support very clearly on the headphone packaging. Most Android phones support aptX as do many personal media players. You’ll also find aptX support on a number of high-quality Bluetooth headphones. Apple relies on the AAC codec for Bluetooth streaming. However, wireless headphones that support AAC aren’t as common as aptX models. Getting the best audio quality from a wireless connection doesn’t require that much technology know-how. Just make sure that your player and headphones both support Bluetooth with aptX. With this in place, you can rest assured that they’ll make beautiful music together.
