Datasets:

kkboy1

/

leaudiocsv

like 0

Bluetooth® LE Audio

A guide to the latest Bluetooth specifications and how they will

change the way we design and use audio and telephony products.

by Nick Hunn

First published January 2022

Paperback ISBN: 979-8-72-723725-0

Hardback ISBN: 979-8-78-846477-0

Copyright © 2022 Nick Hunn

All rights reserved.

The Bluetooth® word mark and logos are registered trademarks owned by Bluetooth SIG, Inc.

and any use of such marks is with permission. Other trademarks and trade names are those

of their respective owners.

www bleaudio.com | www.nickhunn.com

2

 Acknowledgements

I would like to thank everyone who has helped towards the existence of this

book. Without the work of many brilliant people contributing to the

specifications, there would be nothing to write about. They are too numerous

to list here, but they are recorded in each of the Bluetooth® documents. Trying

to develop standards of this complexity results in many days and evenings of

wide-ranging discussions, which have been both challenging and enjoyable. It

has been a pleasure to work with so many people of passion who are always

ready to spend time explaining the intricacies of wireless, audio and its

application.

For taking the time to read through the drafts and coming back with detailed

comments, I would particularly like to thank Richard Einhorn, Kanji Kerai,

Ken Kolderup, Mahendra Tailor, Jonathan Tanner and Martin Woolley. Their

input, from a variety of different reader angles, has helped make this into a

much better book than it would otherwise have been. I must also thank the

Bluetooth SIG for their help and support.

For giving me permission to use the image of Figure 1.8, and also for playing a

pivotal role in kickstarting the whole world of hearables, many thanks to

Nikolaj Hviid of Bragi.

Finally, to my wife, Chris, for reading the endless drafts, as well as the final

book from cover to cover multiple times, questioning everything, as well as

putting up with the many hours I spent writing it.

3

4

Contents

Chapter 1. The background and heritage ................................................................................ 11

1.1 The hearing aid legacy...................................................................................................... 19

1.2 Limitations and proprietary extensions ......................................................................... 20

1.3 What’s in a hearable? ........................................................................................................ 24

Chapter 2. The Bluetooth® LE Audio architecture ............................................................... 29

2.1 The use cases ..................................................................................................................... 29

2.2 The Bluetooth LE Audio architecture .......................................................................... 38

2.3 Talking about Bluetooth LE Audio ............................................................................... 48

Chapter 3. New concepts in Bluetooth® LE Audio .............................................................. 51

3.1 Multi-profile by design..................................................................................................... 51

3.2 The Audio Sink led journey ............................................................................................ 51

3.3 Terminology ...................................................................................................................... 52

3.4 Context Types ................................................................................................................... 56

3.5 Availability ......................................................................................................................... 60

3.6 Audio Location ................................................................................................................. 60

3.7 Channel Allocation (multiplexing) ................................................................................. 61

3.8 Call Control ID - CCID .................................................................................................. 63

3.9 Coordinated Sets............................................................................................................... 64

3.10 Presentation Delay and serialisation of audio data...................................................... 65

3.11 Announcements ................................................................................................................ 71

3.12 Remote controls (Commanders) .................................................................................... 73

Chapter 4. Isochronous Streams .............................................................................................. 75

4.1 Bluetooth LE Audio topologies ..................................................................................... 75

4.2 Isochronous Streams and Roles ..................................................................................... 77

4.3 Connected Isochronous Streams ................................................................................... 80

4.4 Broadcast Isochronous Streams ..................................................................................... 98

4.5 ISOAL – The Isochronous Adaptation Layer ........................................................... 122

Chapter 5. LC3, latency and QoS ........................................................................................... 125

5.1 Introduction .................................................................................................................... 125

5.2 Codecs and latency ......................................................................................................... 126