Rather than stopping voices/sources when the device becomes disconnected, the
context can be set to leave them alone. As a consequence, their state will
remain as playing and they'll keep their last known sample offset indefinately.
For applications mindful of this behavior, it will allow resetting or reopening
the device to reconnect and automatically resume where it left off.
The inverted atomic flag replaces test_and_set+clear with test_and_clear+set,
essentially inverting the flag status. This makes more logical sense for
flagging dirty state, which is less confusing than flagging clean state. The
one caveat is ATOMIC_FLAG_INIT (or default construction in C++20) initializes
the state to true rather than false.
This uses a bit more memory (each voice needs to hold buffers for the
deinterleaved samples of each channel, instead of just one buffer for the
current channel being mixed on the device), but it will allow for handling
formats that need or prefer their channels decoded together.
NULL devices are still checked, but invalid non-NULL device handles will invoke
undefined behavior, as will attempting to close the device while the function
is being executed (modifying the device state while the function is being
called was inadvertently already UB, and will now remain so).
This change is solely so alcRenderSamplesSOFT can be used in a buffer callback,
and other places that need functions to be real-time safe. The verification
requires locking to access the device list, which isn't allowed in a real-time
callback.
Used when upsampling low-order ambisonic signals to higher order. Rather than a
hardcoded 400hz, it ensures a consistent crossover point when an ambdec
configuration is used. It can also allow for an alsoft config option.
