#define ARDOURBACKEND_API LIBARDOUR_DLL_EXPORT
#else
#define ARDOURBACKEND_API LIBARDOUR_DLL_IMPORT
-#endif
+#endif
#define ARDOURBACKEND_LOCAL LIBARDOUR_DLL_LOCAL
namespace ARDOUR {
const char* name;
/** Using arg1 and arg2, initialize this audiobackend.
- *
+ *
* Returns zero on success, non-zero otherwise.
*/
int (*instantiate) (const std::string& arg1, const std::string& arg2);
int (*deinstantiate) (void);
/** Factory method to create an AudioBackend-derived class.
- *
+ *
* Returns a valid shared_ptr to the object if successfull,
* or a "null" shared_ptr otherwise.
*/
bool (*available)();
};
+/** AudioBackend is an high-level abstraction for interacting with the operating system's
+ * audio and midi I/O.
+ */
class LIBARDOUR_API AudioBackend : public PortEngine {
public:
AudioBackend (AudioEngine& e, AudioBackendInfo& i) : PortEngine (e), _info (i), engine (e) {}
virtual ~AudioBackend () {}
-
+
enum ErrorCode {
NoError = 0,
BackendInitializationError = -64,
BackendDeinitializationError,
+ BackendReinitializationError,
AudioDeviceOpenError,
AudioDeviceCloseError,
+ AudioDeviceInvalidError,
AudioDeviceNotAvailableError,
AudioDeviceNotConnectedError,
AudioDeviceReservationError,
MidiDeviceNotAvailableError,
MidiDeviceNotConnectedError,
MidiDeviceIOError,
+ SampleFormatNotSupportedError,
SampleRateNotSupportedError,
RequestedInputLatencyNotSupportedError,
RequestedOutputLatencyNotSupportedError,
PeriodSizeNotSupportedError,
PeriodCountNotSupportedError,
DeviceConfigurationNotSupportedError,
+ ChannelCountNotSupportedError,
InputChannelCountNotSupportedError,
OutputChannelCountNotSupportedError,
AquireRealtimePermissionError,
SettingAudioThreadPriorityError,
- SettingMIDIThreadPriorityError
+ SettingMIDIThreadPriorityError,
+ ProcessThreadStartError,
+ FreewheelThreadStartError,
+ PortRegistrationError,
+ PortReconnectError,
+ OutOfMemoryError,
};
static std::string get_error_string (ErrorCode);
* before any device can be selected. Return false otherwise.
*
* Intended mainly to differentiate between meta-APIs like JACK
- * which can still expose different backends (such as ALSA or CoreAudio
+ * which can still expose different backends (such as ALSA or CoreAudio
* or FFADO or netjack) and those like ASIO or CoreAudio which
* do not.
*/
virtual int set_driver (const std::string& /*drivername*/) { return 0; }
/** used to list device names along with whether or not they are currently
- * available.
+ * available.
*/
struct DeviceStatus {
std::string name;
virtual std::vector<DeviceStatus> enumerate_output_devices () const
{ return std::vector<DeviceStatus>(); }
+
+ /** An interface to set buffers/period for playback latency.
+ * useful for ALSA or JACK/ALSA on Linux.
+ *
+ * @return true if the backend supports period-size configuration
+ */
+ virtual bool can_set_period_size () const { return false; }
+
+ /** Returns a vector of supported period-sizes for the given driver */
+ virtual std::vector<uint32_t> available_period_sizes (const std::string& driver) const { return std::vector<uint32_t>(); }
+
+ /** Set the period size to be used.
+ * must be called before starting the backend.
+ */
+ virtual int set_peridod_size (uint32_t) { return -1; }
+
+ /**
+ * @return true if backend supports requesting an update to the device list
+ * and any cached properties associated with the devices.
+ */
+ virtual bool can_request_update_devices () { return false; }
+
+ /**
+ * Request an update to the list of devices returned in the enumerations.
+ * The Backend must return true from can_request_update_devices to support
+ * this interface.
+ * @return true if the devices were updated
+ */
+ virtual bool update_devices () { return false; }
+
+ /**
+ * @return true if backend supports a blocking or buffered mode, false by
+ * default unless implemented by a derived class.
+ */
+ virtual bool can_use_buffered_io () { return false; }
+
+ /**
+ * Set the backend to use a blocking or buffered I/O mode
+ */
+ virtual void set_use_buffered_io (bool) { }
+
+ /**
+ * @return Set the backend to use a blocking or buffered I/O mode, false by
+ * default unless implemented by a derived class.
+ */
+ virtual bool get_use_buffered_io () { return false; }
+
/** Returns a collection of float identifying sample rates that are
* potentially usable with the hardware identified by @param device.
* Any of these values may be supplied in other calls to this backend
virtual bool can_change_sample_rate_when_running () const = 0;
/* Return true if the derived class can change the buffer size of the
* device in use while the device is already being used. Return false
- * otherwise.
+ * otherwise.
*/
virtual bool can_change_buffer_size_when_running () const = 0;
+ /** return true if the backend can measure and update
+ * systemic latencies without restart.
+ */
+ virtual bool can_change_systemic_latency_when_running () const { return false; }
+
/* Set the hardware parameters.
- *
+ *
* If called when the current state is stopped or paused,
* the changes will not take effect until the state changes to running.
*
* If @param yn is true, then the hardware will interleave
* samples for successive channels; otherwise, the hardware will store
* samples for a single channel contiguously.
- *
+ *
* Setting this does not change the fact that all data streams
* to and from Ports are mono (essentially, non-interleaved)
*/
/** Set the number of output channels that should be used
*/
virtual int set_output_channels (uint32_t) = 0;
- /** Set the (additional) input latency that cannot be determined via
+ /** Set the (additional) input latency that cannot be determined via
* the implementation's underlying code (e.g. latency from
* external D-A/D-A converters. Units are samples.
*/
virtual int set_systemic_input_latency (uint32_t) = 0;
- /** Set the (additional) output latency that cannot be determined via
+ /** Set the (additional) output latency that cannot be determined via
* the implementation's underlying code (e.g. latency from
* external D-A/D-A converters. Units are samples.
*/
virtual uint32_t systemic_output_latency () const = 0;
virtual uint32_t systemic_midi_input_latency (std::string const) const = 0;
virtual uint32_t systemic_midi_output_latency (std::string const) const = 0;
+ virtual uint32_t period_size () const { return 0; }
/** override this if this implementation returns true from
* requires_driver_selection()
*/
virtual std::string driver_name() const { return std::string(); }
- /** Return the name of a control application for the
+ /** Return the name of a control application for the
* selected/in-use device. If no such application exists,
* or if no device has been selected or is in-use,
* return an empty string.
virtual void launch_control_app () = 0;
/* @return a vector of strings that describe the available
- * MIDI options.
+ * MIDI options.
*
* These can be presented to the user to decide which
* MIDI drivers, options etc. can be used. The returned strings
virtual bool can_set_systemic_midi_latencies () const = 0;
/* State Control */
-
+
/** Start using the device named in the most recent call
* to set_device(), with the parameters set by various
* the most recent calls to set_sample_rate() etc. etc.
- *
+ *
* At some undetermined time after this function is successfully called,
* the backend will start calling the ::process_callback() method of
* the AudioEngine referenced by @param engine. These calls will
* this pattern, or possibly just this:
*
* http://stackoverflow.com/questions/12139786/good-pratice-default-arguments-for-pure-virtual-method
- */
+ */
int start (bool for_latency_measurement=false) {
return _start (for_latency_measurement);
}
- /** Stop using the device currently in use.
+ /** Stop using the device currently in use.
*
* If the function is successfully called, no subsequent calls to the
* process_callback() of @param engine will be made after the function
* returns, until parameters are reset and start() are called again.
- *
+ *
* The backend is considered to be un-configured after a successful
* return, and requires calls to set hardware parameters before it can be
* start()-ed again. See pause() for a way to avoid this. stop() should
- * only be used when reconfiguration is required OR when there are no
+ * only be used when reconfiguration is required OR when there are no
* plans to use the backend in the future with a reconfiguration.
*
* Return zero if successful, 1 if the device is not in use, negative values on error
*/
virtual int stop () = 0;
- /** Reset device.
+ /** Reset device.
*
* Return zero if successful, negative values on error
*/
* from 0.0 to 1.0
*
* E.g. if the buffer size represents 5msec and current processing
- * takes 1msec, the returned value should be 0.2.
- *
+ * takes 1msec, the returned value should be 0.2.
+ *
* Implementations can feel free to smooth the values returned over
* time (e.g. high pass filtering, or its equivalent).
*/
/* Transport Control (JACK is the only audio API that currently offers
the concept of shared transport control)
*/
-
- /** Attempt to change the transport state to TransportRolling.
+
+ /** Attempt to change the transport state to TransportRolling.
*/
virtual void transport_start () {}
- /** Attempt to change the transport state to TransportStopped.
+ /** Attempt to change the transport state to TransportStopped.
*/
virtual void transport_stop () {}
/** return the current transport state
* timebase, otherwise cease to be the time master for the same.
*
* Return zero on success, non-zero otherwise
- *
+ *
* JACK is the only currently known audio API with the concept of a shared
* transport timebase.
*/
virtual int usecs_per_cycle () const { return 1000000 * (buffer_size() / sample_rate()); }
virtual size_t raw_buffer_size (DataType t) = 0;
-
+
/* Process time */
-
+
/** return the time according to the sample clock in use, measured in
* samples since an arbitrary zero time in the past. The value should
* increase monotonically and linearly, without interruption from any
* source (including CPU frequency scaling).
*
* It is extremely likely that any implementation will use a DLL, since
- * this function can be called from any thread, at any time, and must be
+ * this function can be called from any thread, at any time, and must be
* able to accurately determine the correct sample time.
*
* Can be called from any thread.
/** Return the time since the current buffer process cycle started,
* in samples, according to the sample clock in use.
- *
+ *
* Can ONLY be called from within a process() callback tree (which
* implies that it can only be called by a process thread)
*/
virtual int create_process_thread (boost::function<void()> func) = 0;
/** Wait for all processing threads to exit.
- *
+ *
* Return zero on success, non-zero on failure.
*/
virtual int join_process_threads () = 0;
}
protected:
- AudioBackendInfo& _info;
+ AudioBackendInfo& _info;
AudioEngine& engine;
virtual int _start (bool for_latency_measurement) = 0;
} // namespace
#endif /* __libardour_audiobackend_h__ */
-
+
projects / ardour.git / blobdiff