libcamera's CameraManager runs the event handlers on its own thread,
thus synchronization is needed to ensure correct functionality.
Implement that by collecting hotplug events into a mutex protected queue
and signalling the main loop where they can be processed and the
"object_info" event can be safely emitted.
Using a shared_ptr removes the need for manually calling
`libcamera_manager_release()` to drop the reference as it is done
automatically whenever the shared_ptr is destroyed or reset.
Previously, the libcamera manager `impl` object was neither properly
constructed neither properly destructed. As a consequence, for example,
the shared pointers in the `devices` array weren't properly destructed,
although this has been somewhat mitigated by a previous change
that modifed `clear_devices()`.
Previously, the "impl" object was never properly constructed or
destructed, but it more or less worked out since the memory was initialized
to zero bytes and each member had trivial constructors. Except std::shared_ptr,
but an all zero storage happened to be equivalent to a default constructed
shared_ptr.
However, there was the still the problem that the shared_ptr was never
destructed, so it kept the referenced `Camera` object alive, which lead
to memory leaks.
An additional, somewhat unrelated change is that the "props" struct
is removed, and the device identifier is now stored in an `std::string`.
The reason is that `CameraManager::get()` already takes a const std::string reference,
so an std::string must be constructed in any case, so we might as well
take advantage of that and use `std::string` in the "impl" object as well.
Furthermore, wrap the `impl` struct in an anonymous namespace
to avoid name resolution problems.
Previously, in `remove_device()`, the last device would be copied into
the slot of the to-be-remove device. The problem with this is that it
left the shared_ptr untouched in the previously last slot, and hence
creating an extra reference. Fix this by moving instead of copying.
A similar problem is present in `clear_devices()` which also
did not properly dispose of the shared_ptrs. Fix that by
calling `reset()` on each device's camera pointer.
BlueZ adds the Endpoint property to the Properties dictionary of
SelectProperties.
This allows to know which remote Endpoint is an acceptor, and so which
local transport should be used as an initiator.
Multiple transport from the same device may share the same stream (CIS)
and group (CIG) but for different direction, e.g. a speaker and a
microphone. In this case they are linked.
In this case:
- On acquire, if another transport has already been acquired, the new
transport should not call Acquire or TryAcquire but re-use values from
the previously acquired transport,
- on release, the closing of transport fd and call to Release should be
done only for the last transport.
We can't determine which remote endpoint or device the
SelectConfiguration() call is associated with. For LE Audio BAP, as this
method is called only for the Initiator we set the whole instance as a
Central/Initiator.
This flag is unset on BAP media endpoint removal.
Add methods activate() that is called before first call to run() when
stream starts and deactivate() that is called after last call to run()
when stream stops. This makes it possible for aec-plugins to reset their
state between streams.
DSD64 would be a rate of 44100 * 64 / 8. When packed in U32_BE, we would
negotiate 44100 * 8 / 4 (88200) with the device, this means all rates
from 88200 and up are allowed for DSD64 in U32_BE.
