It can happen that the main AlsaAudioBackend::_device_reservation
is still busy while I/O devices are set. In this case a
dedicated AlsaDeviceReservation needs to be used which can fail
silently.
A common example is disconnecting a USB device while it is in
use. The Halted signal can show the session dialog, which calls
set_input_device_name before the device reservation of the
unplugged device terminated.
ALSA backend modified the internal state when different devices
were used, re-assigning one (usually input-device) to "None"
when it's resampled. This lead to EngineHints not matching the
EngineState, and autostart was disabled, and a dialog
"Engine I/O device has changed since you last opened this session."
Querying available buffersizes and sample-rates requires access
to the device. Almost all ALSA devices are limited to
a single user-space application so we unconditionally try
to request access to the device.
PBD::Transmitter is neither thread-safe nor rt-safe. This likely
fixes a crash on macOS when process-threads are started.
Many threads simultaneously enter coreaudio_process_thread() and
log a message calling `PBD::info << .. << endmsg` simultaneously.
In all years of using these assert()s never triggered. Besides
there are valid_port() tests in other strategic locations that
are not periodically hit in realtime context.
Found via `codespell -q 3 -S *.po,./share/patchfiles,./libs -L ba,buss,busses,doubleclick,hsi,ontop,ro,seh,siz,sord,sur,te,trough,ue`
Follow-up to 364f2f078
"While 'atomic' has a volatile qualifier, this is a historical
artifact and the pointer passed to it should not be volatile."
Furthermore "It is very important that all accesses to a
particular integer or pointer be performed using only this API"
(from https://developer.gnome.org/glib/2.68/glib-Atomic-Operations.html)
Hence initialization of atomic variables is changed to also use
this API, instead of directly initializing the value.
This also fixes a few cases where atomic variables were
accessed directly.
see also libs/pbd/pbd/g_atomic_compat.h
The backend holds `_port_callback_mutex` while disconnecting ports.
In some cases disconnecting a port can drop the last reference
resulting in a port-deletion from the connection handler.
This in turn will eventually aquire the `_port_callback_mutex`
and deadlock.
This is now circumvented by using atomic operations instead of
taking a lock to set the `_port_change_flag`.
The flag is also used to trigger a latency update in some cases,
atomic is preferable to taking a lock to set this flag.
--
Full bt: https://paste.debian.net/1184056/
Short:
#1 in pthread_mutex_lock ()
#2 in ARDOUR::PortEngineSharedImpl::port_connect_add_remove_callback()
#3 in ARDOUR::BackendPort::~BackendPort()
#4 in ARDOUR::DummyPort::~DummyPort()
#6 in ARDOUR::DummyAudioPort::~DummyAudioPort()
#7 in boost::checked_delete<ARDOUR::BackendPort>(ARDOUR::BackendPort*)
#12 in boost::shared_ptr<ARDOUR::ProtoPort>::reset()
#13 in ARDOUR::Port::drop()
#14 in ARDOUR::Port::~Port()
#15 in ARDOUR::AudioPort::~AudioPort()
#17 in ARDOUR::AudioEngine::add_pending_port_deletion(ARDOUR::Port*)
#20 in boost::detail::sp_counted_base::release()
#37 in ARDOUR::PortManager::connect_callback() at libs/ardour/port_manager.cc:788
#38 in ARDOUR::DummyAudioBackend::main_process_thread() at libs/backends/dummy/dummy_audiobackend.cc:1018
The warning "samples per period does not match." never triggered.
Previously not being able to set the requested buffersize was a
fatal error.
This adds support for soundcards that only support msec.
e.g. recent HDA Intel via SOF (Sound Open Firmware)
This allow to restore original engine port-names as set
by the backend. ALSA MIDI, CoreAudio, CoreMIDI and PortAudio
drivers can provide human readable physical port names for
some devices.
This fixes an issue with some soundcards e.g. "AxeFx III".
Device configuration fails unless set_hwpar() is performed
for the capture device before configuring the playack
device (half duplex is fine, too).
This is mainly for RME RayDAT that has a fixed buffersize of 16k:
dev_name : hw:HDSPMxc2f6c5,0
channels : 36
min_rate : 32000
max_rate : 192000
min_bufz : 16384
max_bufz : 16384
min_nper : 4
max_nper : 512
However nperiod configuration determines the effective latency
regardless.
This is similar to https://github.com/jackaudio/jack1/blob/master/drivers/alsa/alsa_driver.c#L476-L486
