+ virtual framecnt_t signal_latency() const { return 0; }
+
+ virtual void set_input_latency (framecnt_t);
+ framecnt_t input_latency () const { return _input_latency; }
+
+ virtual int set_block_size (pframes_t /*nframes*/) { return 0; }
+ virtual bool requires_fixed_sized_buffers() const { return false; }
+
+ /** @param result_required true if, on return from this method, @a bufs is required to contain valid data;
+ * if false, the method need not bother writing to @a bufs if it doesn't want to.
+ */
+ virtual void run (BufferSet& /*bufs*/, framepos_t /*start_frame*/, framepos_t /*end_frame*/, double speed, pframes_t /*nframes*/, bool /*result_required*/) {}
+ virtual void silence (framecnt_t nframes, framepos_t start_frame) { automation_run (start_frame, nframes); }
+
+ virtual void activate () { _pending_active = true; ActiveChanged(); }
+ virtual void deactivate () { _pending_active = false; ActiveChanged(); }
+ virtual void flush() {}