Bluetooth: Common Audio Profile Shell
This document describes how to run the Common Audio Profile functionality.
CAP Acceptor
The Acceptor will typically be a resource-constrained device, such as a headset, earbud or hearing aid. The Acceptor can initialize a Coordinated Set Identification Service instance, if it is in a pair with one or more other CAP Acceptors.
Using the CAP Acceptor
When the Bluetooth stack has been initialized (bt init), the Acceptor can be registered by
calling cap_acceptor init, which will register the CAS and CSIS services, as well as
register callbacks.
cap_acceptor --help
cap_acceptor - Bluetooth CAP acceptor shell commands
Subcommands:
init :Initialize the service and register callbacks [size <int>]
[rank <int>] [not-lockable] [sirk <data>]
lock :Lock the set
release :Release the set [force]
set_sirk :Set the currently used SIRK <sirk>
get_sirk :Get the currently used SIRK
set_sirk_rsp :Set the response used in SIRK requests <accept, accept_enc,
reject, oob>
Besides initializing the CAS and the CSIS, there are also commands to lock and release the CSIS instance, as well as printing and modifying access to the SIRK of the CSIS.
Setting a new SIRK
This command can modify the currently used SIRK. To get the new RSI to advertise on air,
bt adv-data` or bt advertise must be called again to set the new advertising data.
If CONFIG_BT_CSIP_SET_MEMBER_NOTIFIABLE is enabled, this will also notify connected
clients.
uart:~$ cap_acceptor set_sirk 00112233445566778899aabbccddeeff
Set SIRK updated
Getting the current SIRK
This command can get the currently used SIRK.
uart:~$ cap_acceptor get_sirk
Set SIRK
36 04 9a dc 66 3a a1 a1 |6...f:..
1d 9a 2f 41 01 73 3e 01 |../A.s>.
CAP Initiator
The Initiator will typically be a resource-rich device, such as a phone or PC. The Initiator can discover CAP Acceptors’s CAS and optional CSIS services. The CSIS service can be read to provide information about other CAP Acceptors in the same Coordinated Set. The Initiator can execute stream control procedures on sets of devices, either ad-hoc or Coordinated, and thus provides an easy way to setup multiple streams on multiple devices at once.
Using the CAP Initiator
When the Bluetooth stack has been initialized (bt init), the Initiator can discover CAS and
the optionally included CSIS instance by calling (cap_initiator discover).
cap_initiator --help
cap_initiator - Bluetooth CAP initiator shell commands
Subcommands:
discover :Discover CAS
unicast_start :Unicast Start [csip] [sinks <cnt> (default 1)] [sources <cnt>
(default 1)] [conns (<cnt> | all) (default 1)]
unicast_list :Unicast list streams
unicast_update :Unicast Update <all | stream [stream [stream...]]>
unicast_stop :Unicast stop streams <all | stream [stream [stream...]]>
unicast_cancel :Unicast cancel current procedure
Before being able to perform any stream operation, the device must also perform the
bap discover operation to discover the ASEs and PAC records. The bap init
command also needs to be called.
When connected
Discovering CAS and CSIS on a device:
uart:~$ cap_initiator discover
discovery completed with CSIS
Discovering ASEs and PAC records on a device:
uart:~$ bap discover
conn 0x81cc260: #0: codec 0x81d5b28 dir 0x01
codec 0x06 cid 0x0000 vid 0x0000 count 5
data #0: type 0x01 len 2
00000000: f5 |. |
data #1: type 0x02 len 1
data #2: type 0x03 len 1
data #3: type 0x04 len 4
00000000: 1e 00 f0 |... |
data #4: type 0x05 len 1
meta #0: type 0x01 len 2
00000000: 06 |. |
dir 1 loc 1
snk ctx 6 src ctx 6
Conn: 0x81cc260, Sink #0: ep 0x81e4248
Conn: 0x81cc260, Sink #1: ep 0x81e46a8
conn 0x81cc260: #0: codec 0x81d5f00 dir 0x02
codec 0x06 cid 0x0000 vid 0x0000 count 5
data #0: type 0x01 len 2
00000000: f5 |. |
data #1: type 0x02 len 1
data #2: type 0x03 len 1
data #3: type 0x04 len 4
00000000: 1e 00 f0 |... |
data #4: type 0x05 len 1
meta #0: type 0x01 len 2
00000000: 06 |. |
dir 2 loc 1
snk ctx 6 src ctx 6
Conn: 0x81cc260, Source #0: ep 0x81e5c88
Conn: 0x81cc260, Source #1: ep 0x81e60e8
Discover complete: err 0
Both of the above commands should be done for each device that you want to use in the set.
To use multiple devices, simply connect to more and then use bt select the device to execute
the commands on.
Once all devices have been connected and the respective discovery commands have been called, the
cap_initiator unicast_start command can be used to put one or more streams into the
streaming state.
uart:~$ cap_initiator unicast_start sinks 1 sources 0 conns all
Setting up 1 sinks and 0 sources on each (2) conn
Starting 1 streams
Unicast start completed
To stop all the streams that has been started, the cap_initiator unicast_stop command can be
used.
uart:~$ cap_initiator unicast_stop all
Unicast stop completed
CAP Commander
The Commander will typically be a either co-located with a CAP Initiator or be on a separate resource-rich mobile device, such as a phone or smartwatch. The Commander can discover CAP Acceptors’s CAS and optional CSIS services. The CSIS service can be read to provide information about other CAP Acceptors in the same Coordinated Set. The Commander can provide information about broadcast sources to CAP Acceptors or coordinate capture and rendering information such as mute or volume states.
Using the CAP Commander
When the Bluetooth stack has been initialized (bt init), the Commander can discover CAS and
the optionally included CSIS instance by calling (cap_commander discover).
cap_commander --help
cap_commander - Bluetooth CAP commander shell commands
Subcommands:
discover :Discover CAS
change_volume :Change volume on all connections <volume>
change_volume_offset :Change volume offset per connection <volume_offset
[volume_offset [...]]>
Before being able to perform any stream operation, the device must also perform the
bap discover operation to discover the ASEs and PAC records. The bap init
command also needs to be called.
When connected
Discovering CAS and CSIS on a device
uart:~$ cap_commander discover
discovery completed with CSIS
Setting the volume on all connected devices
uart:~$ vcp_vol_ctlr discover
VCP discover done with 1 VOCS and 1 AICS
uart:~$ cap_commander change_volume 15
uart:~$ cap_commander change_volume 15
Setting volume to 15 on 2 connections
VCP volume 15, mute 0
VCP vol_set done
VCP volume 15, mute 0
VCP flags 0x01
VCP vol_set done
Volume change completed
Setting the volume offset on one or more devices
The offsets are set by connection index, so connection index 0 gets the first offset, and index 1 gets the second offset, etc.:
uart:~$ bt connect <device A>
Connected: <device A>
uart:~$ cap_commander discover
discovery completed with CSIS
uart:~$ vcp_vol_ctlr discover
VCP discover done with 1 VOCS and 1 AICS
uart:~$
uart:~$ bt connect <device B>
Connected: <device B>
uart:~$ cap_commander discover
discovery completed with CSIS
uart:~$ vcp_vol_ctlr discover
VCP discover done with 1 VOCS and 1 AICS
uart:~$
uart:~$ cap_commander change_volume_offset 10
Setting volume offset on 1 connections
VOCS inst 0x200140a4 offset 10
Offset set for inst 0x200140a4
Volume offset change completed
uart:~$
uart:~$ cap_commander change_volume_offset 10 15
Setting volume offset on 2 connections
Offset set for inst 0x200140a4
VOCS inst 0x20014188 offset 15
Offset set for inst 0x20014188
Volume offset change completed
Setting the volume mute on all connected devices
uart:~$ bt connect <device A>
Connected: <device A>
uart:~$ cap_commander discover
discovery completed with CSIS
uart:~$ vcp_vol_ctlr discover
VCP discover done with 1 VOCS and 1 AICS
uart:~$
uart:~$ bt connect <device B>
Connected: <device B>
uart:~$ cap_commander discover
discovery completed with CSIS
uart:~$ vcp_vol_ctlr discover
VCP discover done with 1 VOCS and 1 AICS
uart:~$
uart:~$ cap_commander change_volume_mute 1
Setting volume mute to 1 on 2 connections
VCP volume 100, mute 1
VCP mute done
VCP volume 100, mute 1
VCP mute done
Volume mute change completed
uart:~$ cap_commander change_volume_mute 0
Setting volume mute to 0 on 2 connections
VCP volume 100, mute 0
VCP unmute done
VCP volume 100, mute 0
VCP unmute done
Volume mute change completed