Bluetooth: Basic Audio Profile
This document describes how to run Basic Audio Profile functionality which includes:
Capabilities and Endpoint discovery
Audio Stream Endpoint procedures
Commands
bap --help
Subcommands:
init
select_broadcast : <stream>
create_broadcast : [preset <preset_name>] [enc <broadcast_code>]
start_broadcast :
stop_broadcast :
delete_broadcast :
create_broadcast_sink : 0x<broadcast_id>
sync_broadcast : 0x<bis_index> [[[0x<bis_index>] 0x<bis_index>] ...]
[bcode <broadcast code> || bcode_str <broadcast code
as string>]
stop_broadcast_sink : Stops broadcast sink
term_broadcast_sink :
discover : [dir: sink, source]
config : <direction: sink, source> <index> [loc <loc_bits>]
[preset <preset_name>]
stream_qos : interval [framing] [latency] [pd] [sdu] [phy] [rtn]
qos : Send QoS configure for Unicast Group
enable : [context]
stop
list
print_ase_info : Print ASE info for default connection
metadata : [context]
start
disable
release
select_unicast : <stream>
preset : <sink, source, broadcast> [preset]
[config
[freq <frequency>]
[dur <duration>]
[chan_alloc <location>]
[frame_len <frame length>]
[frame_blks <frame blocks>]]
[meta
[pref_ctx <context>]
[stream_ctx <context>]
[program_info <program info>]
[stream_lang <ISO 639-3 lang>]
[ccid_list <ccids>]
[parental_rating <rating>]
[program_info_uri <URI>]
[audio_active_state <state>]
[bcast_flag]
[extended <meta>]
[vendor <meta>]]
send : Send to Audio Stream [data]
start_sine : Start sending a LC3 encoded sine wave [all]
stop_sine : Stop sending a LC3 encoded sine wave [all]
recv_stats : Sets or gets the receive statistics reporting interval
in # of packets
set_location : <direction: sink, source> <location bitmask>
set_context : <direction: sink, source><context bitmask> <type:
supported, available>
Command |
Depends |
Allowed States |
Next States |
|---|---|---|---|
init |
none |
any |
none |
discover |
init |
any |
any |
config |
discover |
idle/codec-configured/qos-configured |
codec-configured |
qos |
config |
codec-configured/qos-configured |
qos-configured |
enable |
qos |
qos-configured |
enabling |
[start] |
enable |
enabling |
streaming |
disable |
enable |
enabling/streaming |
disabling |
[stop] |
disable |
disabling |
qos-configure/idle |
release |
config |
any |
releasing/codec-configure/idle |
list |
none |
any |
none |
select_unicast |
none |
any |
none |
connect |
discover |
idle/codec-configured/qos-configured |
codec-configured |
send |
enable |
streaming |
none |
Example Central
Connect and establish a stream:
uart:~$ bt init
uart:~$ bap init
uart:~$ bt connect <address>
uart:~$ gatt exchange-mtu
uart:~$ bap discover sink
uart:~$ bap config sink 0
uart:~$ bap qos
uart:~$ bap enable
Or using connect command:
uart:~$ bt init
uart:~$ bap init
uart:~$ bt connect <address>
uart:~$ gatt exchange-mtu
uart:~$ bap discover sink
uart:~$ bap connect sink 0
Disconnect and release:
uart:~$ bap disable
uart:~$ bap release
Example Peripheral
Listen:
uart:~$ bt init
uart:~$ bap init
uart:~$ bt advertise on
Server initiated disable and release:
uart:~$ bap disable
uart:~$ bap release
Example Broadcast Source
Create and establish a broadcast source stream:
uart:~$ bap init
uart:~$ bap create_broadcast
uart:~$ bap start_broadcast
Stop and release a broadcast source stream:
uart:~$ bap stop_broadcast
uart:~$ bap delete_broadcast
Example Broadcast Sink
Scan for and establish a broadcast sink stream.
The command bap create_broadcast_sink 0xEF6716 will either use existing periodic advertising
sync (if exist) or start scanning and sync to the periodic advertising before syncing to the BIG.
uart:~$ bap init
uart:~$ bap broadcast_scan on
Found broadcaster with ID 0xEF6716 and addr 3D:A5:F9:35:0B:19 (random) and sid 0x00
uart:~$ bap create_broadcast_sink 0xEF6716
Attempting to PA sync to the broadcaster
PA synced to broadcast with broadcast ID 0xEF6716
Attempting to sync to the BIG
Received BASE from sink 0x20031fac:
Presentation delay: 40000
Subgroup count: 2
Subgroup[0]:
codec cfg id 0x06 cid 0x0000 vid 0x0000
data_count 4
data #0: type 0x01 len 1
00000000: 03 |. |
data #1: type 0x02 len 1
00000000: 01 |. |
data #2: type 0x03 len 4
00000000: 01 00 00 00 |.... |
data #3: type 0x04 len 2
00000000: 28 00 |(. |
meta_count 4
meta #0: type 0x02 len 2
00000000: 01 00 |.. |
BIS[0] index 0x01
Subgroup[1]:
codec cfg id 0x06 cid 0x0000 vid 0x0000
data_count 4
data #0: type 0x01 len 1
00000000: 03 |. |
data #1: type 0x02 len 1
00000000: 01 |. |
data #2: type 0x03 len 4
00000000: 01 00 00 00 |.... |
data #3: type 0x04 len 2
00000000: 28 00 |(. |
meta_count 4
meta #0: type 0x02 len 2
00000000: 01 00 |.. |
BIS[1] index 0x01
[0]: 0x01
[1]: 0x01
Possible indexes: 0x01 0x01
Sink 0x20019110 is ready to sync without encryption
uart:~$ bap sync_broadcast 0x01
Syncing to encrypted broadcast
If the broadcast is encrypted, the broadcast code can be entered with the bap sync_broadcast
command as such:
Sink 0x20019110 is ready to sync with encryption
uart:~$ bap sync_broadcast 0x01 bcode 0102030405060708090a0b0c0d0e0f
The broadcast code can be 1-16 values, either as a string or a hexadecimal value.
Sink 0x20019110 is ready to sync with encryption
uart:~$ bap sync_broadcast 0x01 bcode_str thisismycode
Stop and release a broadcast sink stream:
uart:~$ bap stop_broadcast_sink
uart:~$ bap term_broadcast_sink
Init
The init command register local PAC records which are necessary to be
able to configure stream and properly manage capabilities in use.
Depends |
Allowed States |
Next States |
|---|---|---|
none |
any |
none |
uart:~$ bap init
Discover PAC(s) and ASE(s)
Once connected the discover command discover PAC records and ASE
characteristics representing remote endpoints.
Depends |
Allowed States |
Next States |
|---|---|---|
init |
any |
any |
Note
Use command gatt exchange-mtu to make sure the MTU is configured
properly.
uart:~$ gatt exchange-mtu
Exchange pending
Exchange successful
uart:~$ bap discover [type: sink, source]
uart:~$ bap discover sink
cap 0x8175940 type 0x01
codec 0x06 cid 0x0000 vid 0x0000 count 4
data #0: type 0x01 len 1
00000000: 3f |? |
data #1: type 0x02 len 1
00000000: 03 |. |
data #2: type 0x03 len 1
00000000: 03 |. |
data #3: type 0x04 len 4
00000000: 1e 00 f0 00 |.... |
meta #0: type 0x01 len 2
00000000: 06 00 |.. |
meta #1: type 0x02 len 2
00000000: ff 03 |.. |
ep 0x81754e0
ep 0x81755d4
Discover complete: err 0
Select preset
The preset command can be used to either print the default preset
configuration or set a different one, it is worth noting that it doesn’t change
any stream previously configured.
uart:~$ bap preset
preset - <sink, source, broadcast> [preset]
[config
[freq <frequency>]
[dur <duration>]
[chan_alloc <location>]
[frame_len <frame length>]
[frame_blks <frame blocks>]]
[meta
[pref_ctx <context>]
[stream_ctx <context>]
[program_info <program info>]
[stream_lang <ISO 639-3 lang>]
[ccid_list <ccids>]
[parental_rating <rating>]
[program_info_uri <URI>]
[audio_active_state <state>]
[bcast_flag]
[extended <meta>]
[vendor <meta>]]
uart:~$ bap preset sink
16_2_1
codec 0x06 cid 0x0000 vid 0x0000 count 4
data #0: type 0x01 len 1
data #1: type 0x02 len 1
data #2: type 0x03 len 4
00000000: 01 00 00 |... |
data #3: type 0x04 len 2
00000000: 28 |( |
meta #0: type 0x02 len 2
00000000: 06 |. |
QoS: interval 10000 framing 0x00 phy 0x02 sdu 40 rtn 2 latency 10 pd 40000
uart:~$ bap preset sink 32_2_1
32_2_1
codec 0x06 cid 0x0000 vid 0x0000 count 4
data #0: type 0x01 len 1
data #1: type 0x02 len 1
data #2: type 0x03 len 4
00000000: 01 00 00 |... |
data #3: type 0x04 len 2
00000000: 50 |P |
meta #0: type 0x02 len 2
00000000: 06 |. |
QoS: interval 10000 framing 0x00 phy 0x02 sdu 80 rtn 2 latency 10 pd 40000
Configure preset
The bap preset command can also be used to configure the preset used for the subsequent
commands. It is possible to add or set (or reset) any value. To reset the preset, the command can simply be run without the config or meta parameter. The parameters are using the
assigned numbers values.
uart:~$ bap preset sink 32_2_1
32_2_1
codec cfg id 0x06 cid 0x0000 vid 0x0000 count 16
data #0: type 0x01 value_len 1
00000000: 06 |. |
data #1: type 0x02 value_len 1
00000000: 01 |. |
data #2: type 0x03 value_len 4
00000000: 03 00 00 00 |.... |
data #3: type 0x04 value_len 2
00000000: 50 00 |P. |
meta #0: type 0x02 value_len 2
00000000: 08 00 |.. |
QoS: interval 10000 framing 0x00 phy 0x02 sdu 80 rtn 2 latency 10 pd 40000
uart:~$ bap preset sink 32_2_1 config freq 10
32_2_1
codec cfg id 0x06 cid 0x0000 vid 0x0000 count 16
data #0: type 0x01 value_len 1
00000000: 0a |. |
data #1: type 0x02 value_len 1
00000000: 01 |. |
data #2: type 0x03 value_len 4
00000000: 03 00 00 00 |.... |
data #3: type 0x04 value_len 2
00000000: 50 00 |P. |
meta #0: type 0x02 value_len 2
00000000: 08 00 |.. |
QoS: interval 10000 framing 0x00 phy 0x02 sdu 80 rtn 2 latency 10 pd 40000
uart:~$ bap preset sink 32_2_1 config freq 10 meta stream_lang "eng" stream_ctx 4
32_2_1
codec cfg id 0x06 cid 0x0000 vid 0x0000 count 16
data #0: type 0x01 value_len 1
00000000: 0a |. |
data #1: type 0x02 value_len 1
00000000: 01 |. |
data #2: type 0x03 value_len 4
00000000: 03 00 00 00 |.... |
data #3: type 0x04 value_len 2
00000000: 50 00 |P. |
meta #0: type 0x02 value_len 2
00000000: 04 00 |.. |
meta #1: type 0x04 value_len 3
00000000: 65 6e 67 |eng |
QoS: interval 10000 framing 0x00 phy 0x02 sdu 80 rtn 2 latency 10 pd 40000
Configure Codec
The config command attempts to configure a stream for the given
direction using a preset codec configuration which can either be passed directly
or in case it is omitted the default preset is used.
Depends |
Allowed States |
Next States |
|---|---|---|
discover |
idle/codec-configured/qos-configured |
codec-configured |
uart:~$ bap config <direction: sink, source> <index> [loc <loc_bits>] [preset <preset_name>]
uart:~$ bap config sink 0
ASE Codec Config: conn 0x8173800 ep 0x81754e0 cap 0x816a360
codec 0x06 cid 0x0000 vid 0x0000 count 3
data #0: type 0x01 len 1
00000000: 02 |. |
data #1: type 0x02 len 1
00000000: 01 |. |
data #2: type 0x04 len 2
00000000: 28 00 |(. |
meta #0: type 0x02 len 2
00000000: 02 00 |.. |
ASE Codec Config stream 0x8179e60
Default ase: 1
ASE config: preset 16_2_1
Configure Stream QoS
The stream_qos Sets a new stream QoS.
uart:~$ bap stream_qos <interval> [framing] [latency] [pd] [sdu] [phy] [rtn]
uart:~$ bap stream_qos 10
Configure QoS
The qos command attempts to configure the stream QoS using the preset
configuration, each individual QoS parameter can be set with use optional
parameters.
Depends |
Allowed States |
Next States |
|---|---|---|
config |
qos-configured/codec-configured |
qos-configured |
uart:~$ bap qos
Enable
The enable command attempts to enable the stream previously configured,
if the remote peer accepts then the ISO connection procedure is also initiated.
Depends |
Allowed States |
Next States |
|---|---|---|
qos |
qos-configured |
enabling |
uart:~$ bap enable [context]
uart:~$ bap enable Media
Start
The start command is only necessary when acting as a sink as it
indicates to the source the stack is ready to start receiving data.
Depends |
Allowed States |
Next States |
|---|---|---|
enable |
enabling |
streaming |
uart:~$ bap start
Disable
The disable command attempts to disable the stream previously enabled,
if the remote peer accepts then the ISO disconnection procedure is also
initiated.
Depends |
Allowed States |
Next States |
|---|---|---|
enable |
enabling/streaming |
disabling |
uart:~$ bap disable
Stop
The stop command is only necessary when acting as a sink as it indicates
to the source the stack is ready to stop receiving data.
Depends |
Allowed States |
Next States |
|---|---|---|
disable |
disabling |
qos-configure/idle |
uart:~$ bap stop
Release
The release command releases the current stream and its configuration.
Depends |
Allowed States |
Next States |
|---|---|---|
config |
any |
releasing/codec-configure/idle |
uart:~$ bap release
List
The list command list the available streams.
Depends |
Allowed States |
Next States |
|---|---|---|
none |
any |
none |
uart:~$ bap list
*0: ase 0x01 dir 0x01 state 0x01
Select Unicast
The select_unicast command set a unicast stream as default.
Depends |
Allowed States |
Next States |
|---|---|---|
none |
any |
none |
uart:~$ bap select <ase>
uart:~$ bap select 0x01
Default stream: 1
To select a broadcast stream:
uart:~$ bap select 0x01 broadcast
Default stream: 1 (broadcast)
Send
The send command sends data over BAP Stream.
Depends |
Allowed States |
Next States |
|---|---|---|
enable |
streaming |
none |
uart:~$ bap send [count]
uart:~$ bap send
Audio sending...