Add API to enforce valid device selection.

[ardour.git] / libs / ardour / ardour / audio_backend.h

diff --git a/libs/ardour/ardour/audio_backend.h b/libs/ardour/ardour/audio_backend.h
index 73310bddb63ea1cae25e5b26e4a08b7b60413bdd..6523eb5081995535741a7dcb28e65a198bc828d3 100644 (file)
--- a/libs/ardour/ardour/audio_backend.h
+++ b/libs/ardour/ardour/audio_backend.h
@@ -80,6 +80,9 @@ struct LIBARDOUR_API AudioBackendInfo {
     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:
 
@@ -199,6 +202,14 @@ class LIBARDOUR_API AudioBackend : public PortEngine {
      */
     virtual bool use_separate_input_and_output_devices () const { return false; }
 
+    /* Return true if the backend uses separate I/O devices only for the case
+     * of allowing one to be "None".
+     *
+     * ie. Input Device must match Output Device, except if either of them
+     * is get_standard_device_name (DeviceNone).
+     */
+    virtual bool match_input_output_devices_or_none () const { return false; }
+
     /** Returns a collection of DeviceStatuses identifying devices discovered
      * by this backend since the start of the process.
      *
@@ -228,6 +239,22 @@ class LIBARDOUR_API AudioBackend : public PortEngine {
     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.
@@ -242,6 +269,23 @@ class LIBARDOUR_API AudioBackend : public PortEngine {
         */
        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
@@ -334,6 +378,11 @@ class LIBARDOUR_API AudioBackend : public PortEngine {
      */
     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,
@@ -426,6 +475,7 @@ class LIBARDOUR_API AudioBackend : public PortEngine {
     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()