It has 20 years of organic growth and includes a lot of lessons learned from the initial underspecification. Lots of profiles were specified but never used (video delivery, over bluetooth, anyone?). Many were not fully thought through and had to be revised (often in nasty ways to remain backwards-compatible). Sadly backwards compatibility makes it worse and worse every year. If you go and write a stack that complies with the spec 100%, you'll find that it works with maybe 50% of devices out there.

BT 4.0 was a chance to start over, and it will help a lot, in time... BT 5.1 will likely finally bring stereo audio over BT LE, with a cleaner spec than A2DP is. But once again, until all the EDR (classic) devices out there are trashed, BT classic remains a huge pain in everyone's rear and a mandatory thing to support. How soon is that? More than 10 years from now! Why? Cars are a major BT use case and many still ship with BT 2.1 car kits. People do not replace cars as easily as headphones.

source: i work on this currently

> source: i work this currently

You have my deepest condolences. Thank you for your sacrifice.

If BT 4 is better, shouldn't BT 4 devices like the AirPods connected to BT 4 devices like modern Mac computers not have these types of weird problems? :/

In my case, AirPods + MB Pro 2013, BT just disconnects for no reason sometimes, other times it refuses to connect. And it's Apples to Apples. Considering the hefty price tag for both devices, the fact that they often fail to produce sound is shameful.

No. Bt 4 adds LE but audio doesn't go over LE yet so no improvement yet

Are you able to tell me if the codec situation (for A2DP) is as big a mess as it seems? One manufacturer is flat out lying about apt-X support, but it seems that if you want to support it you need DRM everywhere and hefty payments.

Worse

Way over-engineered. What most people don’t realize is that Bluetooth isn’t just a PHY layer, or a data decription or ‘just’ an anything - it’s everything. Who would make a spec to be 6 layers of an OSI model (only a slight exageration).

USB doesn’t really care what you send over it after a few base class types, BT does.

BT Classic is really bad in the type of designed by committee way. BT Low Energy is alright imo, but intentionally limited (no SPP, 16bit SIG approved GATTS, a 5.0 feature doesn’t “need” to fully support 5.0 in order to be called a BTLE5 device). I think the BY SIG is too big to get out of its own way.