Bluetooth AptX on Windows 10

How can I tell if Bluetooth audio is using lossless AptX coded on my Windows 10? My computer - Lenovo T430s - is connected to a Philips AEA2700 receiver.

My LG HBS-730 headset supports aptX and it has a indirect indication to tell whether the headset is connected with aptX codec. Just press and hold the volume up and down buttons simultaneously for 1 second, this is supposed to switch EQs, but has no effect if aptX is working, although you can still hear the beep sound.

Using this method, I found that my regular Intel Bluetooth adapter in Skull Canyon NUC on Windows 10 is actually connected to my headset with aptX codec.

I've no idea whether this has restriction on the Bluetooth adapter hardware, but the built-in adapter of NUC is such a common chipset which is widely used in most Windows laptops.

First of all, your bluetooth audio receiver (Philips AEA2700) supports decoding aptX. That's listed in its specification.

Then it comes to the transmitter. AFAIK there are two types of transmitter for bluetooth audio.

The first type is a USB audio class device (i.e. a USB sound card) with hardware codec. Examples are the ones from Creative, such as BT-W2.

For this type of transmitter, you can safely assume that it will automatically use the "best" codec (i.e. aptX Low-Latency > aptX > SBC) available on both itself and the receiver. And I don't suppose you have ways other than checking its specification to know whether aptX is available.

The second type is a general bluetooth transmitter that supports the A2DP profile. The ones that are equipped in laptops are pretty much always of this type.

This type of transmitter usually relies on software codec(s), which are provided its driver / software stack, such as CSR Harmony.

Take CSR Harmony as an example, when it is used to connect to a aptX-capable receiver, an aptX logo with text such as "You are now connected to an aptX-enabled headset" will pop up for a while.

It appears to me that CSR Harmony has been discontinued though. If true, one of the reasons could be the fact that Windows 10 has aptX codec built in, according to this. I have yet to notice any other indication that aptX will be used if you use the Windows-builtin bluetooth driver / stack though.

P.S. aptX is NOT a lossless codec.