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Bluetooth: Gaming Audio Profile Shell

This document describes how to run the Gaming Audio Profile shell functionality. Unlike most other low-layer profiles, GMAP is a profile that exists and has a service (GMAS) on all devices. Thus both the initiator and acceptor (or central and peripheral) should do a discovery of the remote device’s GMAS to see what GMAP roles and features they support.

Using the GMAP Shell

When the Bluetooth stack has been initialized (bt init), the GMAS can be registered by by calling gmap init. It is also strongly suggested to enable BAP via bap init.

uart:~$ gmap --help
gmap - Bluetooth GMAP shell commands
  init      : [none]
  set_role  : [ugt | ugg | bgr | bgs]
  discover  : [none]
  ac_1      : Unicast audio configuration 1
  ac_2      : Unicast audio configuration 2
  ac_3      : Unicast audio configuration 3
  ac_4      : Unicast audio configuration 4
  ac_5      : Unicast audio configuration 5
  ac_6_i    : Unicast audio configuration 6(i)
  ac_6_ii   : Unicast audio configuration 6(ii)
  ac_7_ii   : Unicast audio configuration 7(ii)
  ac_8_i    : Unicast audio configuration 8(i)
  ac_8_ii   : Unicast audio configuration 8(ii)
  ac_11_i   : Unicast audio configuration 11(i)
  ac_11_ii  : Unicast audio configuration 11(ii)
  ac_12     : Broadcast audio configuration 12
  ac_13     : Broadcast audio configuration 13
  ac_14     : Broadcast audio configuration 14

The set_role command can be used to change the role at runtime, assuming that the device supports the role (the GMAP roles depend on some BAP configurations).

Example Central with GMAP UGT role

Connect and establish Gaming Audio streams using Audio Configuration (AC) 3 (some logging has been omitted for clarity):

uart:~$ bt init
uart:~$ bap init
uart:~$ gmap init
uart:~$ bt connect <address>
uart:~$ gatt exchange-mtu
uart:~$ bap discover
Discover complete: err 0
uart:~$ cap_initiator discover
discovery completed with CSIS
uart:~$ gmap discover
gmap discovered for conn 0x2001c7d8:
     role 0x0f
     ugg_feat 0x07
     ugt_feat 0x6f
     bgs_feat 0x01
     bgr_feat 0x03
uart:~$ bap preset sink 32_2_gr
uart:~$ bap preset source 32_2_gs
uart:~$ gmap ac_3
Starting 2 streams for AC_3
stream 0x20020060 config operation rsp_code 0 reason 0
stream 0x200204d0 config operation rsp_code 0 reason 0
stream 0x200204d0 qos operation rsp_code 0 reason 0
stream 0x20020060 qos operation rsp_code 0 reason 0
Stream 0x20020060 enabled
stream 0x200204d0 enable operation rsp_code 0 reason 0
Stream 0x200204d0 enabled
stream 0x20020060 enable operation rsp_code 0 reason 0
Stream 0x20020060 started
stream 0x200204d0 start operation rsp_code 0 reason 0
Stream 0x200204d0 started
Unicast start completed
uart:~$ bap start_sine
Started transmitting on default_stream 0x20020060
[0]: stream 0x20020060 : TX LC3: 80 (seq_num 24800)