Once Pipewire is started it will try to register a BAP broadcast source media endpoint on UUID 00001852-0000-1000-8000-00805f9b34fb if the media codec that supports BAP and the adapter indicates LE Audio is supported.
When the endpoint is detected (over DBus) by Pipewire and it has a broadcast sink UUID, a new device will be created with the address 00:00:00:00:00:00. This device will be our simulated remote device. This is done because a broadcast source emitting device does not need any connection to start transmitting the audio. This device is set as connected.
When the SetConfiguration DBus method is called and the spa_bt_transport structure with the profile BAP broadcast source is created we switch the device from the one read from DBus to the one created by us. This is done because in BlueZ, when the transport is created, at the Device property, BlueZ sets the adapter as the device that the transport is connected to. Here the device will have the newly created SPA_BT_PROFILE_BAP_BROADCAST_SINK profile connected.
Added code that allows to create a node in the graph for a device connected to the SPA_BT_PROFILE_BAP_BROADCAST_SINK profile.
When a sink contributing to an ISO CIG does not have data, output
silence for it, as long as at least one sink in the CIG is running.
Only if writes to sockets fail, pause all streams to reset
synchronization.
This way we write exactly the same number of packets for each CIS at the
same time, which probably is the best tested configuration in BT
adapters and devices. We also don't then have to pause output if some
sinks are not running or miss their timing, as we generate silence on
the fly.
When using iso-io, have it initialize the codec instance, and have
media-sink uses that instance, so that silence and actual audio are
encoded with the same codec.
Resynchronize ISO streams on playback (re)start, so the stream positions
are aligned immediately. This is better than relying on rate matching
to correct any offsets.
For ISO server sockets, the QOS struct from getsockopt contains values
with different meaning from ISO client socket. Get the values via DBus
instead, which is right in both cases.
Add factored out helper for ISO socket I/O.
ISO sockets need synchronization of writes and audio position for
different stream fds in the same isochronous group, and it's easier to
separate out the part that coordinates it.
