Bluetooth:Shell:Bap: Support for 48kHz high reliability (RTN=4) with iso_interval=20ms

Summary

My goal is to do measurements using the BAP config 48_6_2 with RTN=4 (5 transmissions). Typically, this leads to an iso_interval=20ms (decided by the controller) because the accumulated air time with 5 transmissions would be too high.

When trying to run such a configuration using the nrf auraconfig, it results in a config with RTN=3 (4 transmissions) and iso_interval=10ms.

The goal of this ticket would be to have a way to make the nordic transmit a 48_6_2 Auracast stream 5 transmissions with iso_interval=20ms.

Describe the solution you'd like

When CONFIG_BT_ISO_TEST_PARAMS is enabled extend the command create_broadcast as follow: create_broadcast [preset <preset_name>] [enc <broadcast_code>] [irc <irc>] [pto <pto>] [iso_interval <iso_interval>] [nse <nse>] [bn <bn>] [max_pdu <max_pdu>]

set the values irc, pto and iso_interval to bt_bap_broadcast_source_param and max_pdu, bn, nse to default_source.qos

Alternatives

There is no other alternatives if iso_interval is not set it will not use HCI_LE_Create_BIG_Test which is the only way to force the controller stack to use the value we want.

Additional Context

This is only for broadcast for unicasr there is the HCI_LE_Set_CIG_Parameters_Test which should be used but I have not yet look at it.