So apparently after not advancing an inch for almost 2 decades, Bluetooth voice audio over the Headset Profile and Hands-Free Profile has started getting better with the introduction of mSBC, which reproduces up to 8 kHz (old CVSD only did 4 kHz).
Audio sample:
Gonna look for some pocketable mSBC headset with an earhooked earbud and a long close-to-mouth microphone cos I kinda want to be able to take calls without always pulling my whole-ass phone out of my big zippered pocket. Just have to clarify what Android versions support this mSBC first or if I have to install anything.
Oh, looks like there’s also FastStream, which is a standards-noncompliant solution (hack!) by CSR to stick a similar 16 kSps voice channel in the A2DP protocol (not in HSP, not in HFP) along with the 44.1k or 48k stereo output signal. Needless to say, Bluetooth standards accept no such thing. Yet many companies seem to have liked and implemented the idea (vs. keeping catastrophic 4 kHz lowpass quality, who can blame them).
I tested this with my Avantree Leaf USB transceiver + the BTR3, and I got a nice 7+ kHz spectrum (with higher-frequency artifacts probably from the Opus reencoding applied by Discord where I recorded myself in a voice channel):
This must mean that the BTR3 supports FastStream just like the Avantree, because Avantree do talk about supporting FastStream in their products while saying nothing about mSBC. So this suggests FastStream support is reasonably widespread if it has been around at least since the BTR3 came out, and this also tells us some mainstream Chinese manufacturers are on board with it too.
