Fixes for IO port adding/removing
[ardour.git] / libs / ardour / io.cc
index 1c8de5008abc09a4b84a439ad5c5b7314aeef42a..a30881b4dab25b4c09e58d1f0618f86c6c88b261 100644 (file)
@@ -1,5 +1,5 @@
 /*
-    Copyright (C) 2000 Paul Davis 
+    Copyright (C) 2000-2006 Paul Davis 
 
     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
@@ -14,8 +14,6 @@
     You should have received a copy of the GNU General Public License
     along with this program; if not, write to the Free Software
     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
-
-    $Id$
 */
 
 #include <fstream>
 #include <ardour/audioengine.h>
 #include <ardour/io.h>
 #include <ardour/port.h>
+#include <ardour/audio_port.h>
+#include <ardour/midi_port.h>
 #include <ardour/connection.h>
 #include <ardour/session.h>
 #include <ardour/cycle_timer.h>
 #include <ardour/panner.h>
-#include <ardour/dB.h>
+#include <ardour/buffer_set.h>
+#include <ardour/meter.h>
+#include <ardour/amp.h>
 
 #include "i18n.h"
 
@@ -60,19 +62,19 @@ using namespace PBD;
 
 static float current_automation_version_number = 1.0;
 
-jack_nframes_t IO::_automation_interval = 0;
-const string IO::state_node_name = "IO";
-bool         IO::connecting_legal = false;
-bool         IO::ports_legal = false;
-bool         IO::panners_legal = false;
-sigc::signal<void>                IO::Meter;
-sigc::signal<int>                 IO::ConnectingLegal;
-sigc::signal<int>                 IO::PortsLegal;
-sigc::signal<int>                 IO::PannersLegal;
-sigc::signal<void,uint32_t>  IO::MoreOutputs;
-sigc::signal<int>                 IO::PortsCreated;
+jack_nframes_t               IO::_automation_interval = 0;
+const string                 IO::state_node_name = "IO";
+bool                         IO::connecting_legal = false;
+bool                         IO::ports_legal = false;
+bool                         IO::panners_legal = false;
+sigc::signal<void>           IO::Meter;
+sigc::signal<int>            IO::ConnectingLegal;
+sigc::signal<int>            IO::PortsLegal;
+sigc::signal<int>            IO::PannersLegal;
+sigc::signal<void,ChanCount> IO::MoreChannels;
+sigc::signal<int>            IO::PortsCreated;
 
-Glib::StaticMutex       IO::m_meter_signal_lock = GLIBMM_STATIC_MUTEX_INIT;
+Glib::StaticMutex IO::m_meter_signal_lock = GLIBMM_STATIC_MUTEX_INIT;
 
 /* this is a default mapper of [0 .. 1.0] control values to a gain coefficient.
    others can be imagined. 
@@ -91,37 +93,47 @@ static double direct_gain_to_control (gain_t gain) {
        return pow((6.0*log(gain)/log(2.0)+192.0)/198.0, 8.0);
 }
 
-static bool sort_ports_by_name (Port* a, Port* b)
-{
-       return a->name() < b->name();
-}
-
 
 /** @param default_type The type of port that will be created by ensure_io
  * and friends if no type is explicitly requested (to avoid breakage).
  */
 IO::IO (Session& s, string name,
        int input_min, int input_max, int output_min, int output_max,
-       Buffer::Type default_type)
+       DataType default_type)
        : _session (s),
+      _output_buffers(new BufferSet()),
          _name (name),
          _default_type(default_type),
          _gain_control (*this),
          _gain_automation_curve (0.0, 2.0, 1.0),
-         _input_minimum (input_min),
-         _input_maximum (input_max),
-         _output_minimum (output_min),
-         _output_maximum (output_max)
+         _input_minimum (ChanCount::ZERO),
+         _input_maximum (ChanCount::INFINITE),
+         _output_minimum (ChanCount::ZERO),
+         _output_maximum (ChanCount::INFINITE)
 {
        _panner = new Panner (name, _session);
+       _meter = new PeakMeter (_session);
+
+       if (input_min > 0) {
+               _input_minimum = ChanCount(_default_type, input_min);
+       }
+       if (input_max >= 0) {
+               _input_maximum = ChanCount(_default_type, input_max);
+       }
+       if (output_min > 0) {
+               _output_minimum = ChanCount(_default_type, output_min);
+       }
+       if (output_max >= 0) {
+               _output_maximum = ChanCount(_default_type, output_max);
+       }
+
        _gain = 1.0;
        _desired_gain = 1.0;
        _input_connection = 0;
        _output_connection = 0;
        pending_state_node = 0;
-       _ninputs = 0;
-       _noutputs = 0;
        no_panner_reset = false;
+       _phase_invert = false;
        deferred_state = 0;
 
        apply_gain_automation = false;
@@ -130,31 +142,37 @@ IO::IO (Session& s, string name,
 
        _gain_automation_state = Off;
        _gain_automation_style = Absolute;
-    
-    {
-        // IO::Meter is emitted from another thread so the
-        // Meter signal must be protected.
-        Glib::Mutex::Lock guard (m_meter_signal_lock);
-        m_meter_connection = Meter.connect (mem_fun (*this, &IO::meter));
-    }
+
+       {
+               // IO::Meter is emitted from another thread so the
+               // Meter signal must be protected.
+               Glib::Mutex::Lock guard (m_meter_signal_lock);
+               m_meter_connection = Meter.connect (mem_fun (*this, &IO::meter));
+       }
+       
+       // Connect to our own MoreChannels signal to connect output buffers
+       IO::MoreChannels.connect (mem_fun (*this, &IO::attach_buffers));
 }
 
 IO::~IO ()
 {
-
-    Glib::Mutex::Lock guard (m_meter_signal_lock);
+       Glib::Mutex::Lock guard (m_meter_signal_lock);
+       
        Glib::Mutex::Lock lm (io_lock);
-       vector<Port *>::iterator i;
 
-       for (i = _inputs.begin(); i != _inputs.end(); ++i) {
+       for (PortSet::iterator i = _inputs.begin(); i != _inputs.end(); ++i) {
                _session.engine().unregister_port (*i);
        }
 
-       for (i = _outputs.begin(); i != _outputs.end(); ++i) {
+       for (PortSet::iterator i = _outputs.begin(); i != _outputs.end(); ++i) {
                _session.engine().unregister_port (*i);
        }
 
-    m_meter_connection.disconnect();
+       m_meter_connection.disconnect();
+
+       delete _meter;
+       delete _panner;
+       delete _output_buffers;
 }
 
 void
@@ -162,382 +180,89 @@ IO::silence (jack_nframes_t nframes, jack_nframes_t offset)
 {
        /* io_lock, not taken: function must be called from Session::process() calltree */
 
-       for (vector<Port *>::iterator i = _outputs.begin(); i != _outputs.end(); ++i) {
-               (*i)->silence (nframes, offset);
+       for (PortSet::iterator i = _outputs.begin(); i != _outputs.end(); ++i) {
+               i->get_buffer().silence (nframes, offset);
        }
 }
 
+/** Deliver bufs to the IO's Jack outputs.
+ *
+ * This function should automatically do whatever it necessary to correctly deliver bufs
+ * to the outputs, eg applying gain or pan or whatever else needs to be done.
+ */
 void
-IO::apply_declick (vector<Sample *>& bufs, uint32_t nbufs, jack_nframes_t nframes, gain_t initial, gain_t target, bool invert_polarity)
+IO::deliver_output (BufferSet& bufs, jack_nframes_t start_frame, jack_nframes_t end_frame, jack_nframes_t nframes, jack_nframes_t offset)
 {
-       jack_nframes_t declick = min ((jack_nframes_t)4096, nframes);
-       gain_t delta;
-       Sample *buffer;
-       double fractional_shift;
-       double fractional_pos;
-       gain_t polscale = invert_polarity ? -1.0f : 1.0f;
-
-       if (nframes == 0) return;
+       // FIXME: type specific code doesn't actually need to be here, it will go away in time
        
-       fractional_shift = -1.0/declick;
 
-       if (target < initial) {
-               /* fade out: remove more and more of delta from initial */
-               delta = -(initial - target);
-       } else {
-               /* fade in: add more and more of delta from initial */
-               delta = target - initial;
-       }
-
-       for (uint32_t n = 0; n < nbufs; ++n) {
-
-               buffer = bufs[n];
-               fractional_pos = 1.0;
+       /* ********** AUDIO ********** */
 
-               for (jack_nframes_t nx = 0; nx < declick; ++nx) {
-                       buffer[nx] *= polscale * (initial + (delta * (0.5 + 0.5 * cos (M_PI * fractional_pos))));
-                       fractional_pos += fractional_shift;
-               }
-               
-               /* now ensure the rest of the buffer has the target value
-                  applied, if necessary.
-               */
+       // Apply gain if gain automation isn't playing
+       if ( ! apply_gain_automation) {
                
-               if (declick != nframes) {
+               gain_t dg = _gain; // desired gain
 
-                       if (invert_polarity) {
-                               target = -target;
-                       }
+               {
+                       Glib::Mutex::Lock dm (declick_lock, Glib::TRY_LOCK);
 
-                       if (target == 0.0) {
-                               memset (&buffer[declick], 0, sizeof (Sample) * (nframes - declick));
-                       } else if (target != 1.0) {
-                               for (jack_nframes_t nx = declick; nx < nframes; ++nx) {
-                                       buffer[nx] *= target;
-                               }
+                       if (dm.locked()) {
+                               dg = _desired_gain;
                        }
                }
-       }
-}
-
-void
-IO::pan_automated (vector<Sample*>& bufs, uint32_t nbufs, jack_nframes_t start, jack_nframes_t end, jack_nframes_t nframes, jack_nframes_t offset)
-{
-       Sample* dst;
 
-       /* io_lock, not taken: function must be called from Session::process() calltree */
-
-       if (_noutputs == 0) {
-               return;
+               Amp::run(bufs, nframes, _gain, dg, _phase_invert);
        }
+       
+       // Use the panner to distribute audio to output port buffers
+       if (_panner && !_panner->empty() && !_panner->bypassed()) {
+               _panner->distribute(bufs, output_buffers(), start_frame, end_frame, nframes, offset);
+       } else {
+               const DataType type = DataType::AUDIO;
 
-       if (_noutputs == 1) {
-
-               dst = output(0)->get_buffer (nframes) + offset;
-
-               for (uint32_t n = 0; n < nbufs; ++n) {
-                       if (bufs[n] != dst) {
-                               memcpy (dst, bufs[n], sizeof (Sample) * nframes);
-                       } 
+               // Copy any audio 1:1 to outputs
+               assert(bufs.count().get(DataType::AUDIO) == output_buffers().count().get(DataType::AUDIO));
+               BufferSet::iterator o = output_buffers().begin(type);
+               for (BufferSet::iterator i = bufs.begin(type); i != bufs.end(type); ++i, ++o) {
+                       o->read_from(*i, nframes, offset);
                }
-
-               output(0)->mark_silence (false);
-
-               return;
-       }
-
-       uint32_t o;
-       vector<Port *>::iterator out;
-       vector<Sample *>::iterator in;
-       Panner::iterator pan;
-       Sample* obufs[_noutputs];
-
-       /* the terrible silence ... */
-
-       for (out = _outputs.begin(), o = 0; out != _outputs.end(); ++out, ++o) {
-               obufs[o] = (*out)->get_buffer (nframes) + offset;
-               memset (obufs[o], 0, sizeof (Sample) * nframes);
-               (*out)->mark_silence (false);
-       }
-
-       uint32_t n;
-
-       for (pan = _panner->begin(), n = 0; n < nbufs; ++n, ++pan) {
-               (*pan)->distribute_automated (bufs[n], obufs, start, end, nframes, _session.pan_automation_buffer());
-       }
-}
-
-void
-IO::pan (vector<Sample*>& bufs, uint32_t nbufs, jack_nframes_t nframes, jack_nframes_t offset, gain_t gain_coeff)
-{
-       Sample* dst;
-       Sample* src;
-
-       /* io_lock, not taken: function must be called from Session::process() calltree */
-
-       if (_noutputs == 0) {
-               return;
        }
 
-       /* the panner can be empty if there are no inputs to the 
-          route, but still outputs
-       */
-
-       if (_panner->bypassed() || _panner->empty()) {
-               deliver_output_no_pan (bufs, nbufs, nframes, offset);
-               return;
-       }
-
-       if (_noutputs == 1) {
-
-               dst = output(0)->get_buffer (nframes) + offset;
-
-               if (gain_coeff == 0.0f) {
-
-                       /* only one output, and gain was zero, so make it silent */
-
-                       memset (dst, 0, sizeof (Sample) * nframes); 
-                       
-               } else if (gain_coeff == 1.0f){
-
-                       /* mix all buffers into the output */
-
-                       uint32_t n;
-                       
-                       memcpy (dst, bufs[0], sizeof (Sample) * nframes);
-                       
-                       for (n = 1; n < nbufs; ++n) {
-                               src = bufs[n];
-                               
-                               for (jack_nframes_t n = 0; n < nframes; ++n) {
-                                       dst[n] += src[n];
-                               }
-                       }
-
-                       output(0)->mark_silence (false);
-
-               } else {
-
-                       /* mix all buffers into the output, scaling them all by the gain */
-
-                       uint32_t n;
-
-                       src = bufs[0];
-                       
-                       for (jack_nframes_t n = 0; n < nframes; ++n) {
-                               dst[n] = src[n] * gain_coeff;
-                       }       
 
-                       for (n = 1; n < nbufs; ++n) {
-                               src = bufs[n];
-                               
-                               for (jack_nframes_t n = 0; n < nframes; ++n) {
-                                       dst[n] += src[n] * gain_coeff;
-                               }       
-                       }
-                       
-                       output(0)->mark_silence (false);
-               }
+       /* ********** MIDI ********** */
 
+       // No MIDI, we're done here
+       if (bufs.count().get(DataType::MIDI) == 0) {
                return;
        }
 
-       uint32_t o;
-       vector<Port *>::iterator out;
-       vector<Sample *>::iterator in;
-       Panner::iterator pan;
-       Sample* obufs[_noutputs];
+       const DataType type = DataType::MIDI;
 
-       /* the terrible silence ... */
-
-       /* XXX this is wasteful but i see no way to avoid it */
-       
-       for (out = _outputs.begin(), o = 0; out != _outputs.end(); ++out, ++o) {
-               obufs[o] = (*out)->get_buffer (nframes) + offset;
-               memset (obufs[o], 0, sizeof (Sample) * nframes);
-               (*out)->mark_silence (false);
-       }
-
-       uint32_t n;
-
-       for (pan = _panner->begin(), n = 0; n < nbufs; ++n) {
-               Panner::iterator tmp;
-
-               tmp = pan;
-               ++tmp;
-
-               (*pan)->distribute (bufs[n], obufs, gain_coeff, nframes);
-
-               if (tmp != _panner->end()) {
-                       pan = tmp;
-               }
+       // Copy any MIDI 1:1 to outputs
+       assert(bufs.count().get(DataType::MIDI) == output_buffers().count().get(DataType::MIDI));
+       BufferSet::iterator o = output_buffers().begin(type);
+       for (BufferSet::iterator i = bufs.begin(type); i != bufs.end(type); ++i, ++o) {
+               o->read_from(*i, nframes, offset);
        }
 }
 
 void
-IO::deliver_output (vector<Sample *>& bufs, uint32_t nbufs, jack_nframes_t nframes, jack_nframes_t offset)
+IO::collect_input (BufferSet& outs, jack_nframes_t nframes, jack_nframes_t offset)
 {
-       /* io_lock, not taken: function must be called from Session::process() calltree */
+       assert(outs.available() >= n_inputs());
 
-       if (_noutputs == 0) {
-               return;
-       }
+       outs.set_count(n_inputs());
        
-       if (_panner->bypassed() || _panner->empty()) {
-               deliver_output_no_pan (bufs, nbufs, nframes, offset);
+       if (outs.count() == ChanCount::ZERO)
                return;
-       }
-
 
-       gain_t dg;
-       gain_t pangain = _gain;
-       
-       {
-               Glib::Mutex::Lock dm (declick_lock, Glib::TRY_LOCK);
+       for (DataType::iterator t = DataType::begin(); t != DataType::end(); ++t) {
                
-               if (dm.locked()) {
-                       dg = _desired_gain;
-               } else {
-                       dg = _gain;
+               BufferSet::iterator o = outs.begin(*t);
+               for (PortSet::iterator i = _inputs.begin(*t); i != _inputs.end(*t); ++i, ++o) {
+                       o->read_from(i->get_buffer(), nframes, offset);
                }
-       }
 
-       if (dg != _gain) {
-               apply_declick (bufs, nbufs, nframes, _gain, dg, false);
-               _gain = dg;
-               pangain = 1.0f;
-       } 
-
-       /* simple, non-automation panning to outputs */
-
-       if (_session.transport_speed() > 1.5f || _session.transport_speed() < -1.5f) {
-               pan (bufs, nbufs, nframes, offset, pangain * speed_quietning);
-       } else {
-               pan (bufs, nbufs, nframes, offset, pangain);
-       }
-}
-
-void
-IO::deliver_output_no_pan (vector<Sample *>& bufs, uint32_t nbufs, jack_nframes_t nframes, jack_nframes_t offset)
-{
-       /* io_lock, not taken: function must be called from Session::process() calltree */
-
-       if (_noutputs == 0) {
-               return;
-       }
-
-       gain_t dg;
-       gain_t old_gain = _gain;
-
-       if (apply_gain_automation) {
-
-               /* gain has already been applied by automation code. do nothing here except
-                  speed quietning.
-               */
-
-               _gain = 1.0f;
-               dg = _gain;
-               
-       } else {
-
-               Glib::Mutex::Lock dm (declick_lock, Glib::TRY_LOCK);
-               
-               if (dm.locked()) {
-                       dg = _desired_gain;
-               } else {
-                       dg = _gain;
-               }
-       }
-
-       Sample* src;
-       Sample* dst;
-       uint32_t i;
-       vector<Port*>::iterator o;
-       vector<Sample*> outs;
-       gain_t actual_gain;
-
-       if (dg != _gain) {
-               /* unlikely condition */
-               for (o = _outputs.begin(), i = 0; o != _outputs.end(); ++o, ++i) {
-                       outs.push_back ((*o)->get_buffer (nframes) + offset);
-               }
-       }
-
-       /* reduce nbufs to the index of the last input buffer */
-
-       nbufs--;
-
-       if (_session.transport_speed() > 1.5f || _session.transport_speed() < -1.5f) {
-               actual_gain = _gain * speed_quietning;
-       } else {
-               actual_gain = _gain;
-       }
-       
-       for (o = _outputs.begin(), i = 0; o != _outputs.end(); ++o, ++i) {
-
-               dst = (*o)->get_buffer (nframes) + offset;
-               src = bufs[min(nbufs,i)];
-
-               if (dg != _gain || actual_gain == 1.0f) {
-                       memcpy (dst, src, sizeof (Sample) * nframes);
-               } else if (actual_gain == 0.0f) {
-                       memset (dst, 0, sizeof (Sample) * nframes);
-               } else {
-                       for (jack_nframes_t x = 0; x < nframes; ++x) {
-                               dst[x] = src[x] * actual_gain;
-                       }
-               }
-               
-               (*o)->mark_silence (false);
-       }
-
-       if (dg != _gain) {
-               apply_declick (outs, outs.size(), nframes, _gain, dg, false);
-               _gain = dg;
-       }
-
-       if (apply_gain_automation) {
-               _gain = old_gain;
-       }
-}
-
-void
-IO::collect_input (vector<Sample *>& bufs, uint32_t nbufs, jack_nframes_t nframes, jack_nframes_t offset)
-{
-       /* io_lock, not taken: function must be called from Session::process() calltree */
-
-       vector<Port *>::iterator i;
-       uint32_t n;
-       Sample *last = 0;
-       
-       /* we require that bufs.size() >= 1 */
-
-       for (n = 0, i = _inputs.begin(); n < nbufs; ++i, ++n) {
-               if (i == _inputs.end()) {
-                       break;
-               }
-               
-               /* XXX always read the full extent of the port buffer that
-                  we need. One day, we may use jack_port_get_buffer_at_offset()
-                  or something similar. For now, this simple hack will
-                  have to do.
-
-                  Hack? Why yes .. we only need to read nframes-worth of
-                  data, but the data we want is at `offset' within the
-                  buffer.
-               */
-
-               last = (*i)->get_buffer (nframes+offset) + offset;
-               // the dest buffer's offset has already been applied
-               memcpy (bufs[n], last, sizeof (Sample) * nframes);
-       }
-
-       /* fill any excess outputs with the last input */
-       
-       while (n < nbufs && last) {
-               // the dest buffer's offset has already been applied
-               memcpy (bufs[n], last, sizeof (Sample) * nframes);
-               ++n;
        }
 }
 
@@ -545,14 +270,11 @@ void
 IO::just_meter_input (jack_nframes_t start_frame, jack_nframes_t end_frame, 
                      jack_nframes_t nframes, jack_nframes_t offset)
 {
-       vector<Sample*>& bufs = _session.get_passthru_buffers ();
-       uint32_t nbufs = n_process_buffers ();
+       BufferSet& bufs = _session.get_scratch_buffers (n_inputs());
 
-       collect_input (bufs, nbufs, nframes, offset);
+       collect_input (bufs, nframes, offset);
 
-       for (uint32_t n = 0; n < nbufs; ++n) {
-               _peak_power[n] = Session::compute_peak (bufs[n], nframes, _peak_power[n]);
-       }
+       _meter->run(bufs, nframes);
 }
 
 void
@@ -588,7 +310,7 @@ IO::disconnect_input (Port* our_port, string other_port, void* src)
                        
                        /* check that our_port is really one of ours */
                        
-                       if (find (_inputs.begin(), _inputs.end(), our_port) == _inputs.end()) {
+                       if ( ! _inputs.contains(our_port)) {
                                return -1;
                        }
                        
@@ -624,7 +346,7 @@ IO::connect_input (Port* our_port, string other_port, void* src)
                        
                        /* check that our_port is really one of ours */
                        
-                       if (find (_inputs.begin(), _inputs.end(), our_port) == _inputs.end()) {
+                       if ( ! _inputs.contains(our_port) ) {
                                return -1;
                        }
                        
@@ -656,7 +378,9 @@ IO::disconnect_output (Port* our_port, string other_port, void* src)
                {
                        Glib::Mutex::Lock lm (io_lock);
                        
-                       if (find (_outputs.begin(), _outputs.end(), our_port) == _outputs.end()) {
+                       /* check that our_port is really one of ours */
+                       
+                       if ( ! _outputs.contains(our_port) ) {
                                return -1;
                        }
                        
@@ -691,7 +415,7 @@ IO::connect_output (Port* our_port, string other_port, void* src)
                        
                        /* check that our_port is really one of ours */
                        
-                       if (find (_outputs.begin(), _outputs.end(), our_port) == _outputs.end()) {
+                       if ( ! _outputs.contains(our_port) ) {
                                return -1;
                        }
                        
@@ -717,24 +441,24 @@ IO::set_input (Port* other_port, void* src)
           to the specified source.
        */
 
-       if (_input_minimum > 1 || _input_minimum == 0) {
+       if (_input_minimum.get_total() > 1) {
                /* sorry, you can't do this */
                return -1;
        }
 
        if (other_port == 0) {
-               if (_input_minimum < 0) {
-                       return ensure_inputs (0, false, true, src);
+               if (_input_minimum == ChanCount::ZERO) {
+                       return ensure_inputs (ChanCount::ZERO, false, true, src);
                } else {
                        return -1;
                }
        }
 
-       if (ensure_inputs (1, true, true, src)) {
+       if (ensure_inputs (ChanCount(other_port->type(), 1), true, true, src)) {
                return -1;
        }
 
-       return connect_input (_inputs.front(), other_port->name(), src);
+       return connect_input (_inputs.port(0), other_port->name(), src);
 }
 
 int
@@ -747,41 +471,34 @@ IO::remove_output_port (Port* port, void* src)
                
                {
                        Glib::Mutex::Lock lm (io_lock);
-                       
-                       if (_noutputs - 1 == (uint32_t) _output_minimum) {
+
+                       if (n_outputs() <= _output_minimum) {
                                /* sorry, you can't do this */
                                return -1;
                        }
-                       
-                       for (vector<Port *>::iterator i = _outputs.begin(); i != _outputs.end(); ++i) {
-                               if (*i == port) {
-                                       change = IOChange (change|ConfigurationChanged);
-                                       if (port->connected()) {
-                                               change = IOChange (change|ConnectionsChanged);
-                                       } 
-
-                                       _session.engine().unregister_port (*i);
-                                       _outputs.erase (i);
-                                       _noutputs--;
-                                       drop_output_connection ();
-
-                                       break;
-                               }
-                       }
 
-                       if (change != NoChange) {
+                       if (_outputs.remove(port)) {
+                               change = IOChange (change|ConfigurationChanged);
+
+                               if (port->connected()) {
+                                       change = IOChange (change|ConnectionsChanged);
+                               } 
+
+                               _session.engine().unregister_port (*port);
+                               drop_output_connection ();
+                               
                                setup_peak_meters ();
                                reset_panner ();
                        }
                }
        }
-       
+
        if (change != NoChange) {
-               output_changed (change, src); /* EMIT SIGNAL */
+               output_changed (change, src);
                _session.set_dirty ();
                return 0;
-       }
-
+       } 
+       
        return -1;
 }
 
@@ -789,15 +506,15 @@ IO::remove_output_port (Port* port, void* src)
  *
  * @param destination Name of input port to connect new port to.
  * @param src Source for emitted ConfigurationChanged signal.
- * @param type Data type of port.  Default value (Buffer::NIL) will use this IO's default type.
+ * @param type Data type of port.  Default value (NIL) will use this IO's default type.
  */
 int
-IO::add_output_port (string destination, void* src, Buffer::Type type)
+IO::add_output_port (string destination, void* src, DataType type)
 {
        Port* our_port;
        char name[64];
 
-       if (type == Buffer::NIL)
+       if (type == DataType::NIL)
                type = _default_type;
 
        {
@@ -806,14 +523,14 @@ IO::add_output_port (string destination, void* src, Buffer::Type type)
                { 
                        Glib::Mutex::Lock lm (io_lock);
                        
-                       if (_output_maximum >= 0 && (int) _noutputs == _output_maximum) {
+                       if (n_outputs() >= _output_maximum) {
                                return -1;
                        }
                
                        /* Create a new output port */
                        
                        // FIXME: naming scheme for differently typed ports?
-                       if (_output_maximum == 1) {
+                       if (_output_maximum.get(type) == 1) {
                                snprintf (name, sizeof (name), _("%s/out"), _name.c_str());
                        } else {
                                snprintf (name, sizeof (name), _("%s/out %u"), _name.c_str(), find_output_port_hole());
@@ -824,15 +541,13 @@ IO::add_output_port (string destination, void* src, Buffer::Type type)
                                return -1;
                        }
                        
-                       _outputs.push_back (our_port);
-                       sort (_outputs.begin(), _outputs.end(), sort_ports_by_name);
-                       ++_noutputs;
+                       _outputs.add (our_port);
                        drop_output_connection ();
                        setup_peak_meters ();
                        reset_panner ();
                }
 
-               MoreOutputs (_noutputs); /* EMIT SIGNAL */
+               MoreChannels (n_outputs()); /* EMIT SIGNAL */
        }
 
        if (destination.length()) {
@@ -844,6 +559,7 @@ IO::add_output_port (string destination, void* src, Buffer::Type type)
        // pan_changed (src); /* EMIT SIGNAL */
        output_changed (ConfigurationChanged, src); /* EMIT SIGNAL */
        _session.set_dirty ();
+       
        return 0;
 }
 
@@ -858,29 +574,21 @@ IO::remove_input_port (Port* port, void* src)
                {
                        Glib::Mutex::Lock lm (io_lock);
 
-                       if (((int)_ninputs - 1) < _input_minimum) {
+                       if (n_inputs() <= _input_minimum) {
                                /* sorry, you can't do this */
                                return -1;
                        }
-                       for (vector<Port *>::iterator i = _inputs.begin(); i != _inputs.end(); ++i) {
-
-                               if (*i == port) {
-                                       change = IOChange (change|ConfigurationChanged);
 
-                                       if (port->connected()) {
-                                               change = IOChange (change|ConnectionsChanged);
-                                       } 
+                       if (_inputs.remove(port)) {
+                               change = IOChange (change|ConfigurationChanged);
 
-                                       _session.engine().unregister_port (*i);
-                                       _inputs.erase (i);
-                                       _ninputs--;
-                                       drop_input_connection ();
+                               if (port->connected()) {
+                                       change = IOChange (change|ConnectionsChanged);
+                               } 
 
-                                       break;
-                               }
-                       }
-                       
-                       if (change != NoChange) {
+                               _session.engine().unregister_port (*port);
+                               drop_input_connection ();
+                               
                                setup_peak_meters ();
                                reset_panner ();
                        }
@@ -892,7 +600,7 @@ IO::remove_input_port (Port* port, void* src)
                _session.set_dirty ();
                return 0;
        } 
-
+       
        return -1;
 }
 
@@ -904,12 +612,12 @@ IO::remove_input_port (Port* port, void* src)
  * @param src Source for emitted ConfigurationChanged signal.
  */
 int
-IO::add_input_port (string source, void* src, Buffer::Type type)
+IO::add_input_port (string source, void* src, DataType type)
 {
        Port* our_port;
        char name[64];
        
-       if (type == Buffer::NIL)
+       if (type == DataType::NIL)
                type = _default_type;
 
        {
@@ -918,14 +626,14 @@ IO::add_input_port (string source, void* src, Buffer::Type type)
                { 
                        Glib::Mutex::Lock lm (io_lock);
                        
-                       if (_input_maximum >= 0 && (int) _ninputs == _input_maximum) {
+                       if (n_inputs() >= _input_maximum) {
                                return -1;
                        }
 
                        /* Create a new input port */
                        
                        // FIXME: naming scheme for differently typed ports?
-                       if (_input_maximum == 1) {
+                       if (_input_maximum.get(type) == 1) {
                                snprintf (name, sizeof (name), _("%s/in"), _name.c_str());
                        } else {
                                snprintf (name, sizeof (name), _("%s/in %u"), _name.c_str(), find_input_port_hole());
@@ -935,16 +643,14 @@ IO::add_input_port (string source, void* src, Buffer::Type type)
                                error << string_compose(_("IO: cannot register input port %1"), name) << endmsg;
                                return -1;
                        }
-                       
-                       _inputs.push_back (our_port);
-                       sort (_inputs.begin(), _inputs.end(), sort_ports_by_name);
-                       ++_ninputs;
+
+                       _inputs.add (our_port);
                        drop_input_connection ();
                        setup_peak_meters ();
                        reset_panner ();
                }
 
-               MoreOutputs (_ninputs); /* EMIT SIGNAL */
+               MoreChannels (n_inputs()); /* EMIT SIGNAL */
        }
 
        if (source.length()) {
@@ -957,7 +663,7 @@ IO::add_input_port (string source, void* src, Buffer::Type type)
        // pan_changed (src); /* EMIT SIGNAL */
        input_changed (ConfigurationChanged, src); /* EMIT SIGNAL */
        _session.set_dirty ();
-
+       
        return 0;
 }
 
@@ -970,14 +676,16 @@ IO::disconnect_inputs (void* src)
                {
                        Glib::Mutex::Lock lm (io_lock);
                        
-                       for (vector<Port *>::iterator i = _inputs.begin(); i != _inputs.end(); ++i) {
+                       for (PortSet::iterator i = _inputs.begin(); i != _inputs.end(); ++i) {
                                _session.engine().disconnect (*i);
                        }
 
                        drop_input_connection ();
                }
        }
-        input_changed (ConnectionsChanged, src); /* EMIT SIGNAL */
+       
+       input_changed (ConnectionsChanged, src); /* EMIT SIGNAL */
+       
        return 0;
 }
 
@@ -990,7 +698,7 @@ IO::disconnect_outputs (void* src)
                {
                        Glib::Mutex::Lock lm (io_lock);
                        
-                       for (vector<Port *>::iterator i = _outputs.begin(); i != _outputs.end(); ++i) {
+                       for (PortSet::iterator i = _outputs.begin(); i != _outputs.end(); ++i) {
                                _session.engine().disconnect (*i);
                        }
 
@@ -1000,76 +708,74 @@ IO::disconnect_outputs (void* src)
 
        output_changed (ConnectionsChanged, src); /* EMIT SIGNAL */
        _session.set_dirty ();
+       
        return 0;
 }
 
 bool
-IO::ensure_inputs_locked (uint32_t n, bool clear, void* src)
+IO::ensure_inputs_locked (ChanCount count, bool clear, void* src)
 {
-       Port* input_port;
-       bool changed = false;
-       bool reduced = false;
-       
-       /* remove unused ports */
+       Port* input_port = 0;
+       bool  changed    = false;
 
-       while (_ninputs > n) {
-               _session.engine().unregister_port (_inputs.back());
-               _inputs.pop_back();
-               _ninputs--;
-               reduced = true;
-               changed = true;
-       }
-               
-       /* create any necessary new ports */
-               
-       while (_ninputs < n) {
-               
-               char buf[64];
-               
-               /* Create a new input port */
+
+       for (DataType::iterator t = DataType::begin(); t != DataType::end(); ++t) {
                
-               // FIXME: of what type?
+               const size_t n = count.get(*t);
+       
+               /* remove unused ports */
+               for (size_t i = n_inputs().get(*t); i > n; --i) {
+                       input_port = _inputs.port(*t, i-1);
 
-               if (_input_maximum == 1) {
-                       snprintf (buf, sizeof (buf), _("%s/in"), _name.c_str());
-               }
-               else {
-                       snprintf (buf, sizeof (buf), _("%s/in %u"), _name.c_str(), find_input_port_hole());
+                       assert(input_port);
+                       _inputs.remove(input_port);
+                       _session.engine().unregister_port (*input_port);
+
+                       changed = true;
                }
-               
-               try {
-                       
-                       if ((input_port = _session.engine().register_input_port (_default_type, buf)) == 0) {
-                               error << string_compose(_("IO: cannot register input port %1"), buf) << endmsg;
-                               return -1;
+
+               /* create any necessary new ports */
+               while (n_inputs().get(*t) < n) {
+
+                       char buf[64];
+
+                       if (_input_maximum.get(*t) == 1) {
+                               snprintf (buf, sizeof (buf), _("%s/in"), _name.c_str());
+                       } else {
+                               snprintf (buf, sizeof (buf), _("%s/in %u"), _name.c_str(), find_input_port_hole());
                        }
-               }
 
-               catch (AudioEngine::PortRegistrationFailure& err) {
-                       setup_peak_meters ();
-                       reset_panner ();
-                       /* pass it on */
-                       throw err;
+                       try {
+
+                               if ((input_port = _session.engine().register_input_port (*t, buf)) == 0) {
+                                       error << string_compose(_("IO: cannot register input port %1"), buf) << endmsg;
+                                       return -1;
+                               }
+                       }
+
+                       catch (AudioEngine::PortRegistrationFailure& err) {
+                               setup_peak_meters ();
+                               reset_panner ();
+                               /* pass it on */
+                               throw err;
+                       }
+
+                       _inputs.add (input_port);
+                       changed = true;
                }
-               
-               _inputs.push_back (input_port);
-               sort (_inputs.begin(), _inputs.end(), sort_ports_by_name);
-               ++_ninputs;
-               changed = true;
        }
        
        if (changed) {
                drop_input_connection ();
                setup_peak_meters ();
                reset_panner ();
-               MoreOutputs (_ninputs); /* EMIT SIGNAL */
+               MoreChannels (n_inputs()); /* EMIT SIGNAL */
                _session.set_dirty ();
        }
        
        if (clear) {
                /* disconnect all existing ports so that we get a fresh start */
-                       
-               for (vector<Port *>::iterator i = _inputs.begin(); i != _inputs.end(); ++i) {
+               for (PortSet::iterator i = _inputs.begin(); i != _inputs.end(); ++i) {
                        _session.engine().disconnect (*i);
                }
        }
@@ -1077,24 +783,28 @@ IO::ensure_inputs_locked (uint32_t n, bool clear, void* src)
        return changed;
 }
 
+/** Attach output_buffers to port buffers.
+ * 
+ * Connected to IO's own MoreChannels signal.
+ */
+void
+IO::attach_buffers(ChanCount ignored)
+{
+       _output_buffers->attach_buffers(_outputs);
+}
+
 int
-IO::ensure_io (uint32_t nin, uint32_t nout, bool clear, void* src)
+IO::ensure_io (ChanCount in, ChanCount out, bool clear, void* src)
 {
-       bool in_changed = false;
-       bool out_changed = false;
-       bool in_reduced = false;
-       bool out_reduced = false;
-       bool need_pan_reset;
+       bool in_changed     = false;
+       bool out_changed    = false;
+       bool need_pan_reset = false;
 
-       if (_input_maximum >= 0) {
-               nin = min (_input_maximum, (int) nin);
-       }
+       in = min (_input_maximum, in);
 
-       if (_output_maximum >= 0) {
-               nout = min (_output_maximum, (int) nout);
-       }
+       out = min (_output_maximum, out);
 
-       if (nin == _ninputs && nout == _noutputs && !clear) {
+       if (in == n_inputs() && out == n_outputs() && !clear) {
                return 0;
        }
 
@@ -1104,108 +814,114 @@ IO::ensure_io (uint32_t nin, uint32_t nout, bool clear, void* src)
 
                Port* port;
                
-               if (_noutputs == nout) {
-                       need_pan_reset = false;
-               } else {
+               if (n_outputs() != out) {
                        need_pan_reset = true;
                }
                
-               /* remove unused ports */
-               
-               while (_ninputs > nin) {
-                       _session.engine().unregister_port (_inputs.back());
-                       _inputs.pop_back();
-                       _ninputs--;
-                       in_reduced = true;
-                       in_changed = true;
-               }
-               
-               while (_noutputs > nout) {
-                       _session.engine().unregister_port (_outputs.back());
-                       _outputs.pop_back();
-                       _noutputs--;
-                       out_reduced = true;
-                       out_changed = true;
-               }
-               
-               /* create any necessary new ports */
-               
-               // FIXME: of what type?
+               for (DataType::iterator t = DataType::begin(); t != DataType::end(); ++t) {
 
-               while (_ninputs < nin) {
-                       
-                       char buf[64];
+                       const size_t nin = in.get(*t);
+                       const size_t nout = out.get(*t);
 
-                       /* Create a new input port */
-                       
-                       if (_input_maximum == 1) {
-                               snprintf (buf, sizeof (buf), _("%s/in"), _name.c_str());
+                       Port* output_port = 0;
+                       Port* input_port = 0;
+
+                       /* remove unused output ports */
+                       for (size_t i = n_outputs().get(*t); i > nout; --i) {
+                               output_port = _outputs.port(*t, i-1);
+
+                               assert(output_port);
+                               _outputs.remove(output_port);
+                               _session.engine().unregister_port (*output_port);
+
+                               out_changed = true;
                        }
-                       else {
-                               snprintf (buf, sizeof (buf), _("%s/in %u"), _name.c_str(), find_input_port_hole());
+
+                       /* remove unused input ports */
+                       for (size_t i = n_inputs().get(*t); i > nin; --i) {
+                               input_port = _inputs.port(*t, i-1);
+
+                               assert(input_port);
+                               _inputs.remove(input_port);
+                               _session.engine().unregister_port (*input_port);
+
+                               in_changed = true;
                        }
-                       
-                       try {
-                               if ((port = _session.engine().register_input_port (_default_type, buf)) == 0) {
-                                       error << string_compose(_("IO: cannot register input port %1"), buf) << endmsg;
-                                       return -1;
+
+                       /* create any necessary new input ports */
+
+                       while (n_inputs().get(*t) < nin) {
+
+                               char buf[64];
+
+                               /* Create a new input port */
+
+                               if (_input_maximum.get(*t) == 1) {
+                                       snprintf (buf, sizeof (buf), _("%s/in"), _name.c_str());
+                               } else {
+                                       snprintf (buf, sizeof (buf), _("%s/in %u"), _name.c_str(), find_input_port_hole());
                                }
-                       }
 
-                       catch (AudioEngine::PortRegistrationFailure& err) {
-                               setup_peak_meters ();
-                               reset_panner ();
-                               /* pass it on */
-                               throw err;
-                       }
-               
-                       _inputs.push_back (port);
-                       ++_ninputs;
-                       in_changed = true;
-               }
+                               try {
+                                       if ((port = _session.engine().register_input_port (*t, buf)) == 0) {
+                                               error << string_compose(_("IO: cannot register input port %1"), buf) << endmsg;
+                                               return -1;
+                                       }
+                               }
 
-               /* create any necessary new ports */
-               
-               while (_noutputs < nout) {
-                       
-                       char buf[64];
-                       
-                       /* Create a new output port */
-                       
-                       if (_output_maximum == 1) {
-                               snprintf (buf, sizeof (buf), _("%s/out"), _name.c_str());
-                       } else {
-                               snprintf (buf, sizeof (buf), _("%s/out %u"), _name.c_str(), find_output_port_hole());
-                       }
-                       
-                       try { 
-                               if ((port = _session.engine().register_output_port (_default_type, buf)) == 0) {
-                                       error << string_compose(_("IO: cannot register output port %1"), buf) << endmsg;
-                                       return -1;
+                               catch (AudioEngine::PortRegistrationFailure& err) {
+                                       setup_peak_meters ();
+                                       reset_panner ();
+                                       /* pass it on */
+                                       throw err;
                                }
+
+                               _inputs.add (port);
+                               in_changed = true;
                        }
-                       
-                       catch (AudioEngine::PortRegistrationFailure& err) {
-                               setup_peak_meters ();
-                               reset_panner ();
-                               /* pass it on */
-                               throw err;
+
+                       /* create any necessary new output ports */
+
+                       while (n_outputs().get(*t) < nout) {
+
+                               char buf[64];
+
+                               /* Create a new output port */
+
+                               if (_output_maximum.get(*t) == 1) {
+                                       snprintf (buf, sizeof (buf), _("%s/out"), _name.c_str());
+                               } else {
+                                       snprintf (buf, sizeof (buf), _("%s/out %u"), _name.c_str(), find_output_port_hole());
+                               }
+
+                               try { 
+                                       if ((port = _session.engine().register_output_port (*t, buf)) == 0) {
+                                               error << string_compose(_("IO: cannot register output port %1"), buf) << endmsg;
+                                               return -1;
+                                       }
+                               }
+
+                               catch (AudioEngine::PortRegistrationFailure& err) {
+                                       setup_peak_meters ();
+                                       reset_panner ();
+                                       /* pass it on */
+                                       throw err;
+                               }
+
+                               _outputs.add (port);
+                               out_changed = true;
                        }
-               
-                       _outputs.push_back (port);
-                       ++_noutputs;
-                       out_changed = true;
                }
                
                if (clear) {
                        
                        /* disconnect all existing ports so that we get a fresh start */
                        
-                       for (vector<Port *>::iterator i = _inputs.begin(); i != _inputs.end(); ++i) {
+                       for (PortSet::iterator i = _inputs.begin(); i != _inputs.end(); ++i) {
                                _session.engine().disconnect (*i);
                        }
                        
-                       for (vector<Port *>::iterator i = _outputs.begin(); i != _outputs.end(); ++i) {
+                       for (PortSet::iterator i = _outputs.begin(); i != _outputs.end(); ++i) {
                                _session.engine().disconnect (*i);
                        }
                }
@@ -1217,19 +933,17 @@ IO::ensure_io (uint32_t nin, uint32_t nout, bool clear, void* src)
        }
 
        if (out_changed) {
-               sort (_outputs.begin(), _outputs.end(), sort_ports_by_name);
                drop_output_connection ();
                output_changed (ConfigurationChanged, src); /* EMIT SIGNAL */
        }
        
        if (in_changed) {
-               sort (_inputs.begin(), _inputs.end(), sort_ports_by_name);
                drop_input_connection ();
                input_changed (ConfigurationChanged, src); /* EMIT SIGNAL */
        }
 
        if (in_changed || out_changed) {
-               MoreOutputs (max (_noutputs, _ninputs)); /* EMIT SIGNAL */
+               MoreChannels (max (n_outputs(), n_inputs())); /* EMIT SIGNAL */
                _session.set_dirty ();
        }
 
@@ -1237,99 +951,92 @@ IO::ensure_io (uint32_t nin, uint32_t nout, bool clear, void* src)
 }
 
 int
-IO::ensure_inputs (uint32_t n, bool clear, bool lockit, void* src)
+IO::ensure_inputs (ChanCount count, bool clear, bool lockit, void* src)
 {
        bool changed = false;
 
-       if (_input_maximum >= 0) {
-               n = min (_input_maximum, (int) n);
-               
-               if (n == _ninputs && !clear) {
-                       return 0;
-               }
+       count = min (_input_maximum, count);
+
+       if (count == n_inputs() && !clear) {
+               return 0;
        }
-       
+
        if (lockit) {
                Glib::Mutex::Lock em (_session.engine().process_lock());
                Glib::Mutex::Lock im (io_lock);
-               changed = ensure_inputs_locked (n, clear, src);
+               changed = ensure_inputs_locked (count, clear, src);
        } else {
-               changed = ensure_inputs_locked (n, clear, src);
+               changed = ensure_inputs_locked (count, clear, src);
        }
 
        if (changed) {
                input_changed (ConfigurationChanged, src); /* EMIT SIGNAL */
                _session.set_dirty ();
        }
-
        return 0;
 }
 
 bool
-IO::ensure_outputs_locked (uint32_t n, bool clear, void* src)
+IO::ensure_outputs_locked (ChanCount count, bool clear, void* src)
 {
-       Port* output_port;
-       bool changed = false;
-       bool reduced = false;
-       bool need_pan_reset;
+       Port* output_port    = 0;
+       bool  changed        = false;
+       bool  need_pan_reset = false;
 
-       if (_noutputs == n) {
-               need_pan_reset = false;
-       } else {
+       if (n_outputs() != count) {
                need_pan_reset = true;
        }
        
-       /* remove unused ports */
-       
-       while (_noutputs > n) {
-               
-               _session.engine().unregister_port (_outputs.back());
-               _outputs.pop_back();
-               _noutputs--;
-               reduced = true;
-               changed = true;
-       }
-       
-       /* create any necessary new ports */
-       
-       while (_noutputs < n) {
-               
-               char buf[64];
-               
-               /* Create a new output port */
-               
-               if (_output_maximum == 1) {
-                       snprintf (buf, sizeof (buf), _("%s/out"), _name.c_str());
-               } else {
-                       snprintf (buf, sizeof (buf), _("%s/out %u"), _name.c_str(), find_output_port_hole());
-               }
-               
-               if ((output_port = _session.engine().register_output_port (_default_type, buf)) == 0) {
-                       error << string_compose(_("IO: cannot register output port %1"), buf) << endmsg;
-                       return -1;
+       for (DataType::iterator t = DataType::begin(); t != DataType::end(); ++t) {
+
+               const size_t n = count.get(*t);
+
+               /* remove unused ports */
+               for (size_t i = n_outputs().get(*t); i > n; --i) {
+                       output_port = _outputs.port(*t, i-1);
+
+                       assert(output_port);
+                       _outputs.remove(output_port);
+                       _session.engine().unregister_port (*output_port);
+
+                       changed = true;
                }
-               
-               _outputs.push_back (output_port);
-               sort (_outputs.begin(), _outputs.end(), sort_ports_by_name);
-               ++_noutputs;
-               changed = true;
-               setup_peak_meters ();
 
-               if (need_pan_reset) {
-                       reset_panner ();
+               /* create any necessary new ports */
+               while (n_outputs().get(*t) < n) {
+
+                       char buf[64];
+
+                       if (_output_maximum.get(*t) == 1) {
+                               snprintf (buf, sizeof (buf), _("%s/out"), _name.c_str());
+                       } else {
+                               snprintf (buf, sizeof (buf), _("%s/out %u"), _name.c_str(), find_output_port_hole());
+                       }
+
+                       if ((output_port = _session.engine().register_output_port (*t, buf)) == 0) {
+                               error << string_compose(_("IO: cannot register output port %1"), buf) << endmsg;
+                               return -1;
+                       }
+
+                       _outputs.add (output_port);
+                       changed = true;
+                       setup_peak_meters ();
+
+                       if (need_pan_reset) {
+                               reset_panner ();
+                       }
                }
        }
        
        if (changed) {
                drop_output_connection ();
-               MoreOutputs (_noutputs); /* EMIT SIGNAL */
+               MoreChannels (n_outputs()); /* EMIT SIGNAL */
                _session.set_dirty ();
        }
        
        if (clear) {
                /* disconnect all existing ports so that we get a fresh start */
-               
-               for (vector<Port *>::iterator i = _outputs.begin(); i != _outputs.end(); ++i) {
+               for (PortSet::iterator i = _outputs.begin(); i != _outputs.end(); ++i) {
                        _session.engine().disconnect (*i);
                }
        }
@@ -1338,13 +1045,13 @@ IO::ensure_outputs_locked (uint32_t n, bool clear, void* src)
 }
 
 int
-IO::ensure_outputs (uint32_t n, bool clear, bool lockit, void* src)
+IO::ensure_outputs (ChanCount count, bool clear, bool lockit, void* src)
 {
        bool changed = false;
 
-       if (_output_maximum >= 0) {
-               n = min (_output_maximum, (int) n);
-               if (n == _noutputs && !clear) {
+       if (_output_maximum < ChanCount::INFINITE) {
+               count = min (_output_maximum, count);
+               if (count == n_outputs() && !clear) {
                        return 0;
                }
        }
@@ -1354,9 +1061,9 @@ IO::ensure_outputs (uint32_t n, bool clear, bool lockit, void* src)
        if (lockit) {
                Glib::Mutex::Lock em (_session.engine().process_lock());
                Glib::Mutex::Lock im (io_lock);
-               changed = ensure_outputs_locked (n, clear, src);
+               changed = ensure_outputs_locked (count, clear, src);
        } else {
-               changed = ensure_outputs_locked (n, clear, src);
+               changed = ensure_outputs_locked (count, clear, src);
        }
 
        if (changed) {
@@ -1381,7 +1088,7 @@ IO::reset_panner ()
 {
        if (panners_legal) {
                if (!no_panner_reset) {
-                       _panner->reset (_noutputs, pans_required());
+                       _panner->reset (n_outputs().get(DataType::AUDIO), pans_required());
                }
        } else {
                panner_legal_c.disconnect ();
@@ -1392,7 +1099,7 @@ IO::reset_panner ()
 int
 IO::panners_became_legal ()
 {
-       _panner->reset (_noutputs, pans_required());
+       _panner->reset (n_outputs().get(DataType::AUDIO), pans_required());
        _panner->load (); // automation
        panner_legal_c.disconnect ();
        return 0;
@@ -1446,9 +1153,9 @@ IO::state (bool full_state)
        }
 
        if (need_ins) {
-               for (vector<Port *>::iterator i = _inputs.begin(); i != _inputs.end(); ++i) {
+               for (PortSet::iterator i = _inputs.begin(); i != _inputs.end(); ++i) {
                        
-                       const char **connections = (*i)->get_connections();
+                       const char **connections = i->get_connections();
                        
                        if (connections && connections[0]) {
                                str += '{';
@@ -1483,9 +1190,9 @@ IO::state (bool full_state)
        if (need_outs) {
                str = "";
                
-               for (vector<Port *>::iterator i = _outputs.begin(); i != _outputs.end(); ++i) {
+               for (PortSet::iterator i = _outputs.begin(); i != _outputs.end(); ++i) {
                        
-                       const char **connections = (*i)->get_connections();
+                       const char **connections = i->get_connections();
                        
                        if (connections && connections[0]) {
                                
@@ -1516,11 +1223,13 @@ IO::state (bool full_state)
        snprintf (buf, sizeof(buf), "%2.12f", gain());
        node->add_property ("gain", buf);
 
-       snprintf (buf, sizeof(buf)-1, "%d,%d,%d,%d",
-                 _input_minimum,
-                 _input_maximum,
-                 _output_minimum,
-                 _output_maximum);
+       // FIXME: this is NOT sufficient!
+       const int in_min  = (_input_minimum == ChanCount::ZERO) ? -1 : _input_minimum.get(_default_type);
+       const int in_max  = (_input_maximum == ChanCount::INFINITE) ? -1 : _input_maximum.get(_default_type);
+       const int out_min = (_output_minimum == ChanCount::ZERO) ? -1 : _output_minimum.get(_default_type);
+       const int out_max = (_output_maximum == ChanCount::INFINITE) ? -1 : _output_maximum.get(_default_type);
+
+       snprintf (buf, sizeof(buf)-1, "%d,%d,%d,%d", in_min, in_max, out_min, out_max);
 
        node->add_property ("iolimits", buf);
 
@@ -1612,12 +1321,18 @@ IO::set_state (const XMLNode& node)
                _id = prop->value ();
        }
 
+       size_t in_min =  -1;
+       size_t in_max  = -1;
+       size_t out_min = -1;
+       size_t out_max = -1;
+
        if ((prop = node.property ("iolimits")) != 0) {
-               sscanf (prop->value().c_str(), "%d,%d,%d,%d", 
-                       &_input_minimum,
-                       &_input_maximum,
-                       &_output_minimum,
-                       &_output_maximum);
+               sscanf (prop->value().c_str(), "%zd,%zd,%zd,%zd",
+                       &in_min, &in_max, &out_min, &out_max);
+               _input_minimum = ChanCount(_default_type, in_min);
+               _input_maximum = ChanCount(_default_type, in_max);
+               _output_minimum = ChanCount(_default_type, out_min);
+               _output_maximum = ChanCount(_default_type, out_max);
        }
        
        if ((prop = node.property ("gain")) != 0) {
@@ -1735,7 +1450,8 @@ IO::create_ports (const XMLNode& node)
 
        no_panner_reset = true;
 
-       if (ensure_io (num_inputs, num_outputs, true, this)) {
+       // FIXME: audio-only
+       if (ensure_io (ChanCount(DataType::AUDIO, num_inputs), ChanCount(DataType::AUDIO, num_outputs), true, this)) {
                error << string_compose(_("%1: cannot create I/O ports"), _name) << endmsg;
                return -1;
        }
@@ -1819,7 +1535,8 @@ IO::set_inputs (const string& str)
                return 0;
        }
 
-       if (ensure_inputs (nports, true, true, this)) {
+       // FIXME: audio-only
+       if (ensure_inputs (ChanCount(DataType::AUDIO, nports), true, true, this)) {
                return -1;
        }
 
@@ -1869,7 +1586,8 @@ IO::set_outputs (const string& str)
                return 0;
        }
 
-       if (ensure_outputs (nports, true, true, this)) {
+       // FIXME: audio-only
+       if (ensure_outputs (ChanCount(DataType::AUDIO, nports), true, true, this)) {
                return -1;
        }
 
@@ -1961,16 +1679,16 @@ IO::set_name (string name, void* src)
                return 0;
        }
 
-       for (vector<Port *>::iterator i = _inputs.begin(); i != _inputs.end(); ++i) {
-               string current_name = (*i)->short_name();
+       for (PortSet::iterator i = _inputs.begin(); i != _inputs.end(); ++i) {
+               string current_name = i->short_name();
                current_name.replace (current_name.find (_name), _name.length(), name);
-               (*i)->set_name (current_name);
+               i->set_name (current_name);
        }
 
-       for (vector<Port *>::iterator i = _outputs.begin(); i != _outputs.end(); ++i) {
-               string current_name = (*i)->short_name();
+       for (PortSet::iterator i = _outputs.begin(); i != _outputs.end(); ++i) {
+               string current_name = i->short_name();
                current_name.replace (current_name.find (_name), _name.length(), name);
-               (*i)->set_name (current_name);
+               i->set_name (current_name);
        }
 
        _name = name;
@@ -1982,23 +1700,59 @@ IO::set_name (string name, void* src)
 void
 IO::set_input_minimum (int n)
 {
-       _input_minimum = n;
+       if (n < 0)
+               _input_minimum = ChanCount::ZERO;
+       else
+               _input_minimum = ChanCount(_default_type, n);
 }
 
 void
 IO::set_input_maximum (int n)
 {
-       _input_maximum = n;
+       if (n < 0)
+               _input_maximum = ChanCount::INFINITE;
+       else
+               _input_maximum = ChanCount(_default_type, n);
 }
 
 void
 IO::set_output_minimum (int n)
 {
-       _output_minimum = n;
+       if (n < 0)
+               _output_minimum = ChanCount::ZERO;
+       else
+               _output_minimum = ChanCount(_default_type, n);
 }
 
 void
 IO::set_output_maximum (int n)
+{
+       if (n < 0)
+               _output_maximum = ChanCount::INFINITE;
+       else
+               _output_maximum = ChanCount(_default_type, n);
+}
+
+void
+IO::set_input_minimum (ChanCount n)
+{
+       _input_minimum = n;
+}
+
+void
+IO::set_input_maximum (ChanCount n)
+{
+       _input_maximum = n;
+}
+
+void
+IO::set_output_minimum (ChanCount n)
+{
+       _output_minimum = n;
+}
+
+void
+IO::set_output_maximum (ChanCount n)
 {
        _output_maximum = n;
 }
@@ -2008,8 +1762,8 @@ IO::set_port_latency (jack_nframes_t nframes)
 {
        Glib::Mutex::Lock lm (io_lock);
 
-       for (vector<Port *>::iterator i = _outputs.begin(); i != _outputs.end(); ++i) {
-               (*i)->set_latency (nframes);
+       for (PortSet::iterator i = _outputs.begin(); i != _outputs.end(); ++i) {
+               i->set_latency (nframes);
        }
 }
 
@@ -2023,8 +1777,8 @@ IO::output_latency () const
 
        /* io lock not taken - must be protected by other means */
 
-       for (vector<Port *>::const_iterator i = _outputs.begin(); i != _outputs.end(); ++i) {
-               if ((latency = _session.engine().get_port_total_latency (*(*i))) > max_latency) {
+       for (PortSet::const_iterator i = _outputs.begin(); i != _outputs.end(); ++i) {
+               if ((latency = _session.engine().get_port_total_latency (*i)) > max_latency) {
                        max_latency = latency;
                }
        }
@@ -2042,8 +1796,8 @@ IO::input_latency () const
 
        /* io lock not taken - must be protected by other means */
 
-       for (vector<Port *>::const_iterator i = _inputs.begin(); i != _inputs.end(); ++i) {
-               if ((latency = _session.engine().get_port_total_latency (*(*i))) > max_latency) {
+       for (PortSet::const_iterator i = _inputs.begin(); i != _inputs.end(); ++i) {
+               if ((latency = _session.engine().get_port_total_latency (*i)) > max_latency) {
                        max_latency = latency;
                }
        }
@@ -2064,7 +1818,8 @@ IO::use_input_connection (Connection& c, void* src)
                
                drop_input_connection ();
                
-               if (ensure_inputs (limit, false, false, src)) {
+               // FIXME connections only work for audio-only
+               if (ensure_inputs (ChanCount(DataType::AUDIO, limit), false, false, src)) {
                        return -1;
                }
 
@@ -2077,13 +1832,13 @@ IO::use_input_connection (Connection& c, void* src)
                        
                        for (Connection::PortList::const_iterator i = pl.begin(); i != pl.end(); ++i) {
                                
-                               if (!_inputs[n]->connected_to ((*i))) {
+                               if (!_inputs.port(n)->connected_to ((*i))) {
                                        
                                        /* clear any existing connections */
                                        
-                                       _session.engine().disconnect (_inputs[n]);
+                                       _session.engine().disconnect (*_inputs.port(n));
                                        
-                               } else if (_inputs[n]->connected() > 1) {
+                               } else if (_inputs.port(n)->connected() > 1) {
                                        
                                        /* OK, it is connected to the port we want,
                                           but its also connected to other ports.
@@ -2094,7 +1849,7 @@ IO::use_input_connection (Connection& c, void* src)
                                           the one we want.
                                        */
                                        
-                                       _session.engine().disconnect (_inputs[n]);
+                                       _session.engine().disconnect (*_inputs.port(n));
                                        
                                }
                        }
@@ -2107,9 +1862,9 @@ IO::use_input_connection (Connection& c, void* src)
                        
                        for (Connection::PortList::const_iterator i = pl.begin(); i != pl.end(); ++i) {
                                
-                               if (!_inputs[n]->connected_to ((*i))) {
+                               if (!_inputs.port(n)->connected_to ((*i))) {
                                        
-                                       if (_session.engine().connect (*i, _inputs[n]->name())) {
+                                       if (_session.engine().connect (*i, _inputs.port(n)->name())) {
                                                return -1;
                                        }
                                }
@@ -2142,7 +1897,8 @@ IO::use_output_connection (Connection& c, void* src)
                        
                drop_output_connection ();
 
-               if (ensure_outputs (limit, false, false, src)) {
+               // FIXME: audio-only
+               if (ensure_outputs (ChanCount(DataType::AUDIO, limit), false, false, src)) {
                        return -1;
                }
 
@@ -2156,13 +1912,13 @@ IO::use_output_connection (Connection& c, void* src)
                                
                        for (Connection::PortList::const_iterator i = pl.begin(); i != pl.end(); ++i) {
                                        
-                               if (!_outputs[n]->connected_to ((*i))) {
+                               if (!_outputs.port(n)->connected_to ((*i))) {
 
                                        /* clear any existing connections */
 
-                                       _session.engine().disconnect (_outputs[n]);
+                                       _session.engine().disconnect (*_outputs.port(n));
 
-                               } else if (_outputs[n]->connected() > 1) {
+                               } else if (_outputs.port(n)->connected() > 1) {
 
                                        /* OK, it is connected to the port we want,
                                           but its also connected to other ports.
@@ -2173,7 +1929,7 @@ IO::use_output_connection (Connection& c, void* src)
                                           the one we want.
                                        */
                                                
-                                       _session.engine().disconnect (_outputs[n]);
+                                       _session.engine().disconnect (*_outputs.port(n));
                                }
                        }
                }
@@ -2186,9 +1942,9 @@ IO::use_output_connection (Connection& c, void* src)
                                
                        for (Connection::PortList::const_iterator i = pl.begin(); i != pl.end(); ++i) {
                                        
-                               if (!_outputs[n]->connected_to ((*i))) {
+                               if (!_outputs.port(n)->connected_to ((*i))) {
                                                
-                                       if (_session.engine().connect (_outputs[n]->name(), *i)) {
+                                       if (_session.engine().connect (_outputs.port(n)->name(), *i)) {
                                                return -1;
                                        }
                                }
@@ -2286,27 +2042,6 @@ IO::GainControllable::get_value (void) const
        return direct_gain_to_control (io.effective_gain());
 }
 
-void
-IO::reset_peak_meters ()
-{
-       uint32_t limit = max (_ninputs, _noutputs);
-
-       for (uint32_t i = 0; i < limit; ++i) {
-               _peak_power[i] = 0;
-       }
-}
-
-void
-IO::setup_peak_meters ()
-{
-       uint32_t limit = max (_ninputs, _noutputs);
-
-       while (_peak_power.size() < limit) {
-               _peak_power.push_back (0);
-               _visible_peak_power.push_back (0);
-       }
-}
-
 UndoAction
 IO::get_memento() const
 {
@@ -2326,6 +2061,12 @@ IO::state_factory (std::string why) const
        return state;
 }
 
+void
+IO::setup_peak_meters()
+{
+       _meter->setup(std::max(_inputs.count(), _outputs.count()));
+}
+
 /**
     Update the peak meters.
 
@@ -2339,40 +2080,16 @@ IO::update_meters()
 {
     Glib::Mutex::Lock guard (m_meter_signal_lock);
     
-    Meter();
+    Meter(); /* EMIT SIGNAL */
 }
 
 void
 IO::meter ()
 {
-       Glib::Mutex::Lock lm (io_lock); // READER: meter thread.
-       uint32_t limit = max (_ninputs, _noutputs);
+       // FIXME: Remove this function and just connect signal directly to PeakMeter::meter
        
-       for (uint32_t n = 0; n < limit; ++n) {
-
-               /* XXX we should use atomic exchange here */
-
-               /* grab peak since last read */
-
-               float new_peak = _peak_power[n];
-               _peak_power[n] = 0;
-               
-               /* compute new visible value using falloff */
-
-               if (new_peak > 0.0) {
-                       new_peak = coefficient_to_dB (new_peak);
-               } else {
-                       new_peak = minus_infinity();
-               }
-               
-               if (_session.meter_falloff() == 0.0f || new_peak > _visible_peak_power[n]) {
-                       _visible_peak_power[n] = new_peak;
-               } else {
-                       // do falloff
-                       new_peak = _visible_peak_power[n] - _session.meter_falloff();
-                       _visible_peak_power[n] = max (new_peak, -INFINITY);
-               }
-       }
+       Glib::Mutex::Lock lm (io_lock); // READER: meter thread.
+       _meter->meter();
 }
 
 int
@@ -2652,12 +2369,12 @@ IO::find_input_port_hole ()
 
        for (n = 1; n < UINT_MAX; ++n) {
                char buf[jack_port_name_size()];
-               vector<Port*>::iterator i;
+               PortSet::iterator i = _inputs.begin();
 
                snprintf (buf, jack_port_name_size(), _("%s/in %u"), _name.c_str(), n);
 
-               for (i = _inputs.begin(); i != _inputs.end(); ++i) {
-                       if ((*i)->short_name() == buf) {
+               for ( ; i != _inputs.end(); ++i) {
+                       if (i->short_name() == buf) {
                                break;
                        }
                }
@@ -2682,12 +2399,12 @@ IO::find_output_port_hole ()
 
        for (n = 1; n < UINT_MAX; ++n) {
                char buf[jack_port_name_size()];
-               vector<Port*>::iterator i;
+               PortSet::iterator i = _outputs.begin();
 
                snprintf (buf, jack_port_name_size(), _("%s/out %u"), _name.c_str(), n);
 
-               for (i = _outputs.begin(); i != _outputs.end(); ++i) {
-                       if ((*i)->short_name() == buf) {
+               for ( ; i != _outputs.end(); ++i) {
+                       if (i->short_name() == buf) {
                                break;
                        }
                }
@@ -2699,3 +2416,37 @@ IO::find_output_port_hole ()
        
        return n;
 }
+
+AudioPort*
+IO::audio_input(uint32_t n) const
+{
+       return dynamic_cast<AudioPort*>(input(n));
+}
+
+AudioPort*
+IO::audio_output(uint32_t n) const
+{
+       return dynamic_cast<AudioPort*>(output(n));
+}
+
+MidiPort*
+IO::midi_input(uint32_t n) const
+{
+       return dynamic_cast<MidiPort*>(input(n));
+}
+
+MidiPort*
+IO::midi_output(uint32_t n) const
+{
+       return dynamic_cast<MidiPort*>(output(n));
+}
+
+void
+IO::set_phase_invert (bool yn, void *src)
+{
+       if (_phase_invert != yn) {
+               _phase_invert = yn;
+       }
+       //  phase_invert_changed (src); /* EMIT SIGNAL */
+}
+