track.cc

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/*
    Copyright (C) 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
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    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.
*/
#include "pbd/error.h"

#include "ardour/amp.h"
#include "ardour/debug.h"
#include "ardour/delivery.h"
#include "ardour/diskstream.h"
#include "ardour/io_processor.h"
#include "ardour/meter.h"
#include "ardour/playlist.h"
#include "ardour/port.h"
#include "ardour/processor.h"
#include "ardour/route_group_specialized.h"
#include "ardour/session.h"
#include "ardour/session_playlists.h"
#include "ardour/track.h"
#include "ardour/utils.h"

#include "i18n.h"

using namespace std;
using namespace ARDOUR;
using namespace PBD;

Track::Track (Session& sess, string name, Route::Flag flag, TrackMode mode, DataType default_type)
        : Route (sess, name, flag, default_type)
        , _saved_meter_point (_meter_point)
        , _mode (mode)
        , _monitoring (MonitorAuto)
{
        _freeze_record.state = NoFreeze;
        _declickable = true;
}

Track::~Track ()
{
        DEBUG_TRACE (DEBUG::Destruction, string_compose ("track %1 destructor\n", _name));
}

int
Track::init ()
{
        if (Route::init ()) {
                return -1;
        }

        boost::shared_ptr<Route> rp (shared_from_this());
        boost::shared_ptr<Track> rt = boost::dynamic_pointer_cast<Track> (rp);
        _rec_enable_control = boost::shared_ptr<RecEnableControl> (new RecEnableControl(rt));
        _rec_enable_control->set_flags (Controllable::Toggle);

        /* don't add rec_enable_control to controls because we don't want it to
         * appear as an automatable parameter
         */
        track_number_changed.connect_same_thread (*this, boost::bind (&Track::resync_track_name, this));
        _session.config.ParameterChanged.connect_same_thread (*this, boost::bind (&Track::parameter_changed, this, _1));

        return 0;
}

void
Track::use_new_diskstream ()
{
        boost::shared_ptr<Diskstream> ds = create_diskstream ();

        ds->do_refill_with_alloc ();
        ds->set_block_size (_session.get_block_size ());
        ds->playlist()->set_orig_track_id (id());

        set_diskstream (ds);
}

XMLNode&
Track::get_state ()
{
        return state (true);
}

XMLNode&
Track::state (bool full)
{
        XMLNode& root (Route::state (full));
        root.add_property (X_("monitoring"), enum_2_string (_monitoring));
        root.add_property (X_("saved-meter-point"), enum_2_string (_saved_meter_point));
        root.add_child_nocopy (_rec_enable_control->get_state());
        root.add_child_nocopy (_diskstream->get_state ());
        
        return root;
}       

int
Track::set_state (const XMLNode& node, int version)
{
        if (Route::set_state (node, version)) {
                return -1;
        }

        XMLNode* child;

        if (version >= 3000) {
                if ((child = find_named_node (node, X_("Diskstream"))) != 0) {
                        boost::shared_ptr<Diskstream> ds = diskstream_factory (*child);
                        ds->do_refill_with_alloc ();
                        set_diskstream (ds);
                }
        }

        if (_diskstream) {
                _diskstream->playlist()->set_orig_track_id (id());
        }

        /* set rec-enable control *AFTER* setting up diskstream, because it may
           want to operate on the diskstream as it sets its own state
        */

        XMLNodeList nlist = node.children();
        for (XMLNodeConstIterator niter = nlist.begin(); niter != nlist.end(); ++niter) {
                child = *niter;

                XMLProperty* prop;
                if (child->name() == Controllable::xml_node_name && (prop = child->property ("name")) != 0) {
                        if (prop->value() == X_("recenable")) {
                                _rec_enable_control->set_state (*child, version);
                        }
                }
        }
        
        const XMLProperty* prop;

        if ((prop = node.property (X_("monitoring"))) != 0) {
                _monitoring = MonitorChoice (string_2_enum (prop->value(), _monitoring));
        } else {
                _monitoring = MonitorAuto;
        }

        if ((prop = node.property (X_("saved-meter-point"))) != 0) {
                _saved_meter_point = MeterPoint (string_2_enum (prop->value(), _saved_meter_point));
        } else {
                _saved_meter_point = _meter_point;
        }

        return 0;
}

XMLNode&
Track::get_template ()
{
        return state (false);
}

Track::FreezeRecord::~FreezeRecord ()
{
        for (vector<FreezeRecordProcessorInfo*>::iterator i = processor_info.begin(); i != processor_info.end(); ++i) {
                delete *i;
        }
}

Track::FreezeState
Track::freeze_state() const
{
        return _freeze_record.state;
}

Track::RecEnableControl::RecEnableControl (boost::shared_ptr<Track> t)
        : AutomationControl (t->session(),
                             RecEnableAutomation,
                             ParameterDescriptor(Evoral::Parameter(RecEnableAutomation)),
                             boost::shared_ptr<AutomationList>(),
                             X_("recenable"))
        , track (t)
{
        boost::shared_ptr<AutomationList> gl(new AutomationList(Evoral::Parameter(RecEnableAutomation)));
        set_list (gl);
}

void
Track::RecEnableControl::set_value (double val)
{
        boost::shared_ptr<Track> t = track.lock ();
        if (!t) {
                return;
        }
        
        t->set_record_enabled (val >= 0.5 ? true : false, this);
}

double
Track::RecEnableControl::get_value () const
{
        boost::shared_ptr<Track> t = track.lock ();
        if (!t) {
                return 0;
        }
        
        return (t->record_enabled() ? 1.0 : 0.0);
}

bool
Track::record_enabled () const
{
        return _diskstream && _diskstream->record_enabled ();
}

bool
Track::can_record()
{
        bool will_record = true;
        for (PortSet::iterator i = _input->ports().begin(); i != _input->ports().end() && will_record; ++i) {
                if (!i->connected())
                        will_record = false;
        }

        return will_record;
}

void
Track::prep_record_enabled (bool yn, void *src)
{
        if (!_session.writable()) {
                return;
        }

        if (_freeze_record.state == Frozen) {
                return;
        }

        if (_route_group && src != _route_group && _route_group->is_active() && _route_group->is_recenable()) {
                _route_group->apply (&Track::prep_record_enabled, yn, _route_group);
                return;
        }

        /* keep track of the meter point as it was before we rec-enabled */
        if (!_diskstream->record_enabled()) {
                _saved_meter_point = _meter_point;
        }

        bool will_follow;
        
        if (yn) {
                will_follow = _diskstream->prep_record_enable ();
        } else {
                will_follow = _diskstream->prep_record_disable ();
        }

        if (will_follow) {
                if (yn) {
                        if (_meter_point != MeterCustom) {
                                set_meter_point (MeterInput);
                        }
                } else {
                        set_meter_point (_saved_meter_point);
                }
        }
}

void
Track::set_record_enabled (bool yn, void *src)
{
        if (!_session.writable()) {
                return;
        }

        if (_freeze_record.state == Frozen) {
                return;
        }

        if (_route_group && src != _route_group && _route_group->is_active() && _route_group->is_recenable()) {
                _route_group->apply (&Track::set_record_enabled, yn, _route_group);
                return;
        }

        _diskstream->set_record_enabled (yn);

        _rec_enable_control->Changed ();
}

void
Track::parameter_changed (string const & p)
{
        if (p == "track-name-number") {
                resync_track_name ();
        }
        else if (p == "track-name-take") {
                resync_track_name ();
        }
        else if (p == "take-name") {
                if (_session.config.get_track_name_take()) {
                        resync_track_name ();
                }
        }
}

void
Track::resync_track_name ()
{
        set_name(name());
}

bool
Track::set_name (const string& str)
{
        bool ret;

        if (record_enabled() && _session.actively_recording()) {
                /* this messes things up if done while recording */
                return false;
        }

        string diskstream_name = "";
        if (_session.config.get_track_name_take () && !_session.config.get_take_name ().empty()) {
                // Note: any text is fine, legalize_for_path() fixes this later
                diskstream_name += _session.config.get_take_name ();
                diskstream_name += "_";
        }
        const int64_t tracknumber = track_number();
        if (tracknumber > 0 && _session.config.get_track_name_number()) {
                char num[64], fmt[10];
                snprintf(fmt, sizeof(fmt), "%%0%d" PRId64, _session.track_number_decimals());
                snprintf(num, sizeof(num), fmt, tracknumber);
                diskstream_name += num;
                diskstream_name += "_";
        }
        diskstream_name += str;

        if (diskstream_name == _diskstream_name) {
                return true;
        }
        _diskstream_name = diskstream_name;

        _diskstream->set_write_source_name (diskstream_name);

        boost::shared_ptr<Track> me = boost::dynamic_pointer_cast<Track> (shared_from_this ());
        if (_diskstream->playlist()->all_regions_empty () && _session.playlists->playlists_for_track (me).size() == 1) {
                /* Only rename the diskstream (and therefore the playlist) if
                   a) the playlist has never had a region added to it and
                   b) there is only one playlist for this track.

                   If (a) is not followed, people can get confused if, say,
                   they have notes about a playlist with a given name and then
                   it changes (see mantis #4759).

                   If (b) is not followed, we rename the current playlist and not
                   the other ones, which is a bit confusing (see mantis #4977).
                */
                _diskstream->set_name (str);
        }

        /* save state so that the statefile fully reflects any filename changes */

        if ((ret = Route::set_name (str)) == 0) {
                _session.save_state ("");
        }

        return ret;
}

void
Track::set_latency_compensation (framecnt_t longest_session_latency)
{
        Route::set_latency_compensation (longest_session_latency);
        _diskstream->set_roll_delay (_roll_delay);
}

int
Track::no_roll (pframes_t nframes, framepos_t start_frame, framepos_t end_frame, bool session_state_changing)
{
        Glib::Threads::RWLock::ReaderLock lm (_processor_lock, Glib::Threads::TRY_LOCK);

        if (!lm.locked()) {
                return 0;
        }

        bool can_record = _session.actively_recording ();

        /* no outputs? nothing to do ... what happens if we have sends etc. ? */

        if (n_outputs().n_total() == 0) {
                return 0;
        }

        /* not active ... do the minimum possible by just outputting silence */

        if (!_active) {
                silence (nframes);
                if (_meter_point == MeterInput && (_monitoring & MonitorInput || _diskstream->record_enabled())) {
                        _meter->reset();
                }
                return 0;
        }

        if (session_state_changing) {
                if (_session.transport_speed() != 0.0f) {
                        /* we're rolling but some state is changing (e.g. our diskstream contents)
                           so we cannot use them. Be silent till this is over. Don't declick.

                           XXX note the absurdity of ::no_roll() being called when we ARE rolling!
                        */
                        passthru_silence (start_frame, end_frame, nframes, 0);
                        return 0;
                }
                /* we're really not rolling, so we're either delivery silence or actually
                   monitoring, both of which are safe to do while session_state_changing is true.
                */
        }

        _diskstream->check_record_status (start_frame, can_record);

        bool be_silent;

        MonitorState const s = monitoring_state ();
        /* we are not rolling, so be silent even if we are monitoring disk, as there
           will be no disk data coming in.
        */
        switch (s) {
        case MonitoringSilence:
                be_silent = true;
                break;
        case MonitoringDisk:
                be_silent = true;
                break;
        case MonitoringInput:
                be_silent = false;
                break;
        default:
                be_silent = false;
                break;
        }
        
        //if we have an internal generator, let it play regardless of monitoring state
        if (_have_internal_generator) {
                be_silent = false;
        }
        
        _amp->apply_gain_automation (false);

        /* if have_internal_generator, or .. */

        if (be_silent) {

                if (_meter_point == MeterInput) {
                        /* still need input monitoring and metering */

                        bool const track_rec = _diskstream->record_enabled ();
                        bool const auto_input = _session.config.get_auto_input ();
                        bool const software_monitor = Config->get_monitoring_model() == SoftwareMonitoring;
                        bool const tape_machine_mode = Config->get_tape_machine_mode ();
                        bool no_meter = false;

                        /* this needs a proper K-map
                         * and should be separated into a function similar to monitoring_state()
                         * that also handles roll() states in audio_track.cc, midi_track.cc and route.cc
                         *
                         * see http://www.oofus.co.uk/ardour/Ardour3MonitorModesV3.pdf
                         */
                        if (!auto_input && !track_rec) {
                                no_meter=true;
                        }
                        else if (tape_machine_mode && !track_rec && auto_input) {
                                no_meter=true;
                        }
                        else if (!software_monitor && tape_machine_mode && !track_rec) {
                                no_meter=true;
                        }
                        else if (!software_monitor && !tape_machine_mode && !track_rec && !auto_input) {
                                no_meter=true;
                        }

                        if (no_meter) {
                                BufferSet& bufs (_session.get_silent_buffers (n_process_buffers()));
                                _meter->run (bufs, 0, 0, nframes, true);
                                _input->process_input (boost::shared_ptr<Processor>(), start_frame, end_frame, nframes);
                        } else {
                                _input->process_input (_meter, start_frame, end_frame, nframes);
                        }
                }

                passthru_silence (start_frame, end_frame, nframes, 0);

        } else {

                BufferSet& bufs = _session.get_route_buffers (n_process_buffers());
                
                fill_buffers_with_input (bufs, _input, nframes);

                if (_meter_point == MeterInput) {
                        _meter->run (bufs, start_frame, end_frame, nframes, true);
                }

                passthru (bufs, start_frame, end_frame, nframes, false);
        }

        for (ProcessorList::iterator i = _processors.begin(); i != _processors.end(); ++i) {
                boost::shared_ptr<Delivery> d = boost::dynamic_pointer_cast<Delivery> (*i);
                if (d) {
                        d->flush_buffers (nframes);
                }
        }

        return 0;
}

int
Track::silent_roll (pframes_t nframes, framepos_t /*start_frame*/, framepos_t /*end_frame*/, bool& need_butler)
{
        Glib::Threads::RWLock::ReaderLock lm (_processor_lock, Glib::Threads::TRY_LOCK);
        if (!lm.locked()) {
                framecnt_t playback_distance = _diskstream->calculate_playback_distance(nframes);
                if (can_internal_playback_seek(playback_distance)) {
                        internal_playback_seek(playback_distance);
                }
                return 0;
        }

        if (n_outputs().n_total() == 0 && _processors.empty()) {
                return 0;
        }

        if (!_active) {
                silence (nframes);
                return 0;
        }

        _silent = true;
        _amp->apply_gain_automation(false);

        silence (nframes);

        framecnt_t playback_distance;

        BufferSet& bufs (_session.get_route_buffers (n_process_buffers(), true));

        int const dret = _diskstream->process (bufs, _session.transport_frame(), nframes, playback_distance, false);
        need_butler = _diskstream->commit (playback_distance);
        return dret;
}

void
Track::set_diskstream (boost::shared_ptr<Diskstream> ds)
{
        _diskstream = ds;

        ds->PlaylistChanged.connect_same_thread (*this, boost::bind (&Track::diskstream_playlist_changed, this));
        diskstream_playlist_changed ();
        ds->RecordEnableChanged.connect_same_thread (*this, boost::bind (&Track::diskstream_record_enable_changed, this));
        ds->SpeedChanged.connect_same_thread (*this, boost::bind (&Track::diskstream_speed_changed, this));
        ds->AlignmentStyleChanged.connect_same_thread (*this, boost::bind (&Track::diskstream_alignment_style_changed, this));
}

void
Track::diskstream_playlist_changed ()
{
        PlaylistChanged (); /* EMIT SIGNAL */
}

void
Track::diskstream_record_enable_changed ()
{
        RecordEnableChanged (); /* EMIT SIGNAL */
}

void
Track::diskstream_speed_changed ()
{
        SpeedChanged (); /* EMIT SIGNAL */
}

void
Track::diskstream_alignment_style_changed ()
{
        AlignmentStyleChanged (); /* EMIT SIGNAL */
}

boost::shared_ptr<Playlist>
Track::playlist ()
{
        return _diskstream->playlist ();
}

void
Track::request_input_monitoring (bool m)
{
        _diskstream->request_input_monitoring (m);
}

void
Track::ensure_input_monitoring (bool m)
{
        _diskstream->ensure_input_monitoring (m);
}

bool
Track::destructive () const
{
        return _diskstream->destructive ();
}

list<boost::shared_ptr<Source> > &
Track::last_capture_sources ()
{
        return _diskstream->last_capture_sources ();
}

void
Track::set_capture_offset ()
{
        _diskstream->set_capture_offset ();
}

std::string
Track::steal_write_source_name()
{
        return _diskstream->steal_write_source_name ();
}

void
Track::reset_write_sources (bool r, bool force)
{
        _diskstream->reset_write_sources (r, force);
}

float
Track::playback_buffer_load () const
{
        return _diskstream->playback_buffer_load ();
}

float
Track::capture_buffer_load () const
{
        return _diskstream->capture_buffer_load ();
}

int
Track::do_refill ()
{
        return _diskstream->do_refill ();
}

int
Track::do_flush (RunContext c, bool force)
{
        return _diskstream->do_flush (c, force);
}

void
Track::set_pending_overwrite (bool o)
{
        _diskstream->set_pending_overwrite (o);
}

int
Track::seek (framepos_t p, bool complete_refill)
{
        return _diskstream->seek (p, complete_refill);
}

bool
Track::hidden () const
{
        return _diskstream->hidden ();
}

int
Track::can_internal_playback_seek (framecnt_t p)
{
        return _diskstream->can_internal_playback_seek (p);
}

int
Track::internal_playback_seek (framecnt_t p)
{
        return _diskstream->internal_playback_seek (p);
}

void
Track::non_realtime_input_change ()
{
        _diskstream->non_realtime_input_change ();
}

void
Track::non_realtime_locate (framepos_t p)
{
        Route::non_realtime_locate (p);

        if (!hidden()) {
                /* don't waste i/o cycles and butler calls
                   for hidden (secret) tracks
                */
                _diskstream->non_realtime_locate (p);
        }
}

void
Track::non_realtime_set_speed ()
{
        _diskstream->non_realtime_set_speed ();
}

int
Track::overwrite_existing_buffers ()
{
        return _diskstream->overwrite_existing_buffers ();
}

framecnt_t
Track::get_captured_frames (uint32_t n) const
{
        return _diskstream->get_captured_frames (n);
}

int
Track::set_loop (Location* l)
{
        return _diskstream->set_loop (l);
}

void
Track::transport_looped (framepos_t p)
{
        _diskstream->transport_looped (p);
}

bool
Track::realtime_set_speed (double s, bool g)
{
        return _diskstream->realtime_set_speed (s, g);
}

void
Track::transport_stopped_wallclock (struct tm & n, time_t t, bool g)
{
        _diskstream->transport_stopped_wallclock (n, t, g);
}

bool
Track::pending_overwrite () const
{
        return _diskstream->pending_overwrite ();
}

double
Track::speed () const
{
        return _diskstream->speed ();
}

void
Track::prepare_to_stop (framepos_t t, framepos_t a)
{
        _diskstream->prepare_to_stop (t, a);
}

void
Track::set_slaved (bool s)
{
        _diskstream->set_slaved (s);
}

ChanCount
Track::n_channels ()
{
        return _diskstream->n_channels ();
}

framepos_t
Track::get_capture_start_frame (uint32_t n) const
{
        return _diskstream->get_capture_start_frame (n);
}

AlignStyle
Track::alignment_style () const
{
        return _diskstream->alignment_style ();
}

AlignChoice
Track::alignment_choice () const
{
        return _diskstream->alignment_choice ();
}

framepos_t
Track::current_capture_start () const
{
        return _diskstream->current_capture_start ();
}

framepos_t
Track::current_capture_end () const
{
        return _diskstream->current_capture_end ();
}

void
Track::playlist_modified ()
{
        _diskstream->playlist_modified ();
}

int
Track::use_playlist (boost::shared_ptr<Playlist> p)
{
        int ret = _diskstream->use_playlist (p);
        if (ret == 0) {
                p->set_orig_track_id (id());
        }
        return ret;
}

int
Track::use_copy_playlist ()
{
        int ret =  _diskstream->use_copy_playlist ();

        if (ret == 0) {
                _diskstream->playlist()->set_orig_track_id (id());
        }

        return ret;
}

int
Track::use_new_playlist ()
{
        int ret = _diskstream->use_new_playlist ();

        if (ret == 0) {
                _diskstream->playlist()->set_orig_track_id (id());
        }

        return ret;
}

void
Track::set_align_style (AlignStyle s, bool force)
{
        _diskstream->set_align_style (s, force);
}

void
Track::set_align_choice (AlignChoice s, bool force)
{
        _diskstream->set_align_choice (s, force);
}

bool
Track::using_diskstream_id (PBD::ID id) const
{
        return (id == _diskstream->id ());
}

void
Track::set_block_size (pframes_t n)
{
        Route::set_block_size (n);
        _diskstream->set_block_size (n);
}

void
Track::adjust_playback_buffering ()
{
        if (_diskstream) {
                _diskstream->adjust_playback_buffering ();
        }
}

void
Track::adjust_capture_buffering ()
{
        if (_diskstream) {
                _diskstream->adjust_capture_buffering ();
        }
}

MonitorState
Track::monitoring_state () const
{
        /* Explicit requests */
        
        if (_monitoring & MonitorInput) {
                return MonitoringInput;
        }
                
        if (_monitoring & MonitorDisk) {
                return MonitoringDisk;
        }

        /* This is an implementation of the truth table in doc/monitor_modes.pdf;
           I don't think it's ever going to be too pretty too look at.
        */

        bool const roll = _session.transport_rolling ();
        bool const track_rec = _diskstream->record_enabled ();
        bool const auto_input = _session.config.get_auto_input ();
        bool const software_monitor = Config->get_monitoring_model() == SoftwareMonitoring;
        bool const tape_machine_mode = Config->get_tape_machine_mode ();
        bool session_rec;

        /* I suspect that just use actively_recording() is good enough all the
         * time, but just to keep the semantics the same as they were before
         * sept 26th 2012, we differentiate between the cases where punch is
         * enabled and those where it is not.
         */

        if (_session.config.get_punch_in() || _session.config.get_punch_out()) {
                session_rec = _session.actively_recording ();
        } else {
                session_rec = _session.get_record_enabled();
        }

        if (track_rec) {

                if (!session_rec && roll && auto_input) {
                        return MonitoringDisk;
                } else {
                        return software_monitor ? MonitoringInput : MonitoringSilence;
                }

        } else {

                if (tape_machine_mode) {

                        return MonitoringDisk;

                } else {

                        if (!roll && auto_input) {
                                return software_monitor ? MonitoringInput : MonitoringSilence;
                        } else {
                                return MonitoringDisk;
                        }
                        
                }
        }

        abort(); /* NOTREACHED */
        return MonitoringSilence;
}

void
Track::maybe_declick (BufferSet& bufs, framecnt_t nframes, int declick)
{
        /* never declick if there is an internal generator - we just want it to
           keep generating sound without interruption.

           ditto if we are monitoring inputs.
        */

        if (_have_internal_generator || monitoring_choice() == MonitorInput) {
                return;
        }

        if (!declick) {
                declick = _pending_declick;
        }

        if (declick != 0) {
                Amp::declick (bufs, nframes, declick);
        }
}

framecnt_t
Track::check_initial_delay (framecnt_t nframes, framepos_t& transport_frame)
{
        if (_roll_delay > nframes) {

                _roll_delay -= nframes;
                silence_unlocked (nframes);
                /* transport frame is not legal for caller to use */
                return 0;

        } else if (_roll_delay > 0) {

                nframes -= _roll_delay;
                silence_unlocked (_roll_delay);
                transport_frame += _roll_delay;

                /* shuffle all the port buffers for things that lead "out" of this Route
                   to reflect that we just wrote _roll_delay frames of silence.
                */

                Glib::Threads::RWLock::ReaderLock lm (_processor_lock);
                for (ProcessorList::iterator i = _processors.begin(); i != _processors.end(); ++i) {
                        boost::shared_ptr<IOProcessor> iop = boost::dynamic_pointer_cast<IOProcessor> (*i);
                        if (iop) {
                                iop->increment_port_buffer_offset (_roll_delay);
                        }
                }
                _output->increment_port_buffer_offset (_roll_delay);

                _roll_delay = 0;

        }

        return nframes; 
}

void
Track::set_monitoring (MonitorChoice mc)
{
        if (mc !=  _monitoring) {
                _monitoring = mc;

                for (ProcessorList::iterator i = _processors.begin(); i != _processors.end(); ++i) {
                        (*i)->monitoring_changed ();
                }

                MonitoringChanged (); /* EMIT SIGNAL */
        }
}

MeterState
Track::metering_state () const
{
        bool rv;
        if (_session.transport_rolling ()) {
                // audio_track.cc || midi_track.cc roll() runs meter IFF:
                rv = _meter_point == MeterInput && (_monitoring & MonitorInput || _diskstream->record_enabled());
        } else {
                // track no_roll() always metering if
                rv = _meter_point == MeterInput;
        }
        return rv ? MeteringInput : MeteringRoute;
}