Similar to the listener, separate containers are provided atomically for the
mixer thread to apply updates without needing to block, and a free-list is used
to reuse container objects.
A couple things to note. First, the lock is still used when the effect state's
deviceUpdate method is called to prevent asynchronous calls to reset the device
from interfering. This can be fixed by using the list lock in ALc.c instead.
Secondly, old effect states aren't immediately deleted when the effect type
changes (the actual type, not just its properties). This is because the mixer
thread is intended to be real-time safe, and so can't be freeing anything. They
are cleared away when updates reuse the container they were kept in, and they
don't incur any extra processing cost, but there may be cases where the memory
is kept around until the effect slot is deleted.
This uses a separate container to provide the relevant properties to the
internal update method, using atomic pointer swaps. A free-list is used to
avoid having too many individual containers.
This allows the mixer to update the internal listener properties without
requiring the lock to protect against async updates. It also allows concurrent
read access to the user-facing property values, even the multi-value ones (e.g.
the vectors).
Unfortunately they conflict with AL_EXT_SOURCE_RADIUS, as AL_SOURCE_RADIUS and
AL_BYTE_RW_OFFSETS_SOFT share the same source property value. A replacement for
AL_SOFT_buffer_samples will eventually be made.
This uses a virtual B-Format buffer for mixing, and then uses a dual-band
decoder for improved positional quality. This currently only works with first-
order output since first-order input (from the AL_EXT_BFROMAT extension) would
not sound correct when fed through a second- or third-order decoder.
This also does not currently implement near-field compensation since near-field
rendering effects are not implemented.
This mixes to a 4-channel first-order ambisonics buffer. With ACN ordering and
N3D scaling, this makes it easy to remain compatible with effects that only
care about mono input since channel 0 is an unattenuated mono signal.
This helps the stability of transforms to local space for sources that are at
or near the listener. With a single-precision matrix, even FLT_EPSILON might
not be enough to detect matching positions.
The extension's not going anywhere, and it can't do anything fluidsynth can't.
The code maintenance and bloat is not worth keeping around, and ideally the AL
API would be able to facilitate MIDI-like behavior anyway (envelopes, start-at-
time, etc).
