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BSE: implement Bus::volume_db and Bus::pan properties
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These properties allow changing the volume without changing the pan position
and changing the pan position without changing the volume. We implement
constant power panning.

Signed-off-by: Stefan Westerfeld <stefan@space.twc.de>
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@swesterfeld
swesterfeld committed Sep 13, 2018
1 parent e850a05 commit 752ee2a
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Showing 3 changed files with 117 additions and 21 deletions.
13 changes: 4 additions & 9 deletions bse/bseapi.idl
View file
Expand Up @@ -977,11 +977,6 @@ sequence TrackPartSeq {
TrackPart parts;
};

Const BUS_VOLUME_MIN = 1.58489319246111e-05; /* -96dB */
Const BUS_VOLUME_MAX = 15.8489319246111; /* +24dB */
Const BUS_VOLUME_DEF = 1;
Const BUS_VOLUME_STEP = 0.1;

/// Interface for effect stacks and per-track audio signal routing to the master output.
interface Bus : SubSynth {
Error ensure_output (); ///< Ensure that a bus has an output connection.
Expand All @@ -996,10 +991,10 @@ interface Bus : SubSynth {
bool mute = Bool (_("Mute"), _("Mute: turn off the bus volume"), STANDARD SKIP_DEFAULT, false);
bool solo = Bool (_("Solo"), _("Solo: mute all other busses"), STANDARD SKIP_DEFAULT, false);
bool sync = Bool (_("Sync"), _("Synchronize left and right volume"), STANDARD SKIP_DEFAULT, true);
float64 left_volume = Range (_("Left Volume"), _("Volume adjustment in decibel of left bus channel"), STANDARD ":scale:db-volume",
BUS_VOLUME_MIN, BUS_VOLUME_MAX, BUS_VOLUME_STEP, BUS_VOLUME_DEF);
float64 right_volume = Range (_("Right Volume"), _("Volume adjustment in decibel of right bus channel"), STANDARD ":scale:db-volume",
BUS_VOLUME_MIN, BUS_VOLUME_MAX, BUS_VOLUME_STEP, BUS_VOLUME_DEF);
float64 left_volume = Range (_("Left Volume"), _("Volume factor of the left bus channel"), STANDARD ":scale:db-volume", 0, 1000, 0.1, 1);
float64 right_volume = Range (_("Right Volume"), _("Volume factor of the right bus channel"), STANDARD ":scale:db-volume", 0, 1000, 0.1, 1);
float64 volume_db = Range (_("Volume"), _("Total volume of both channels in decibel"), GUI ":scale:db-value", -96, 12, 5, 0);
float64 pan = Range (_("Pan [%]"), _("Pan position for stereo output"), GUI ":scale", -100, 100, 5, 0);
};
group _("Internals") {
bool master_output = Bool (_("Master Output"), "", STORAGE SKIP_DEFAULT, false);
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117 changes: 105 additions & 12 deletions bse/bsebus.cc
View file
Expand Up @@ -967,21 +967,13 @@ BusImpl::sync (bool val)

notify ("left_volume");
notify ("right_volume");
notify ("volume_db");
notify ("pan");
notify (prop);
}
self->saved_sync = self->synced;
}

static double
volume_clamp (double val)
{
/* keep in sync with bseapi.idl */
const double BUS_VOLUME_MIN = 1.58489319246111e-05; /* -96dB */
const double BUS_VOLUME_MAX = 15.8489319246111; /* +24dB */

return CLAMP (val, BUS_VOLUME_MIN, BUS_VOLUME_MAX);
}

double
BusImpl::left_volume() const
{
Expand All @@ -1000,14 +992,16 @@ BusImpl::left_volume (double val)
auto prop = "left_volume";
push_property_undo (prop);

self->left_volume = volume_clamp (val);
self->left_volume = CLAMP (val, 0, 1000);
if (self->synced)
{
self->right_volume = self->left_volume;
notify ("right_volume");
}
bus_volume_changed (self);

notify ("volume_db");
notify ("pan");
notify (prop);
}
}
Expand All @@ -1030,14 +1024,113 @@ BusImpl::right_volume (double val)
auto prop = "right_volume";
push_property_undo (prop);

self->right_volume = volume_clamp (val);
self->right_volume = CLAMP (val, 0, 1000);
if (self->synced)
{
self->left_volume = self->right_volume;
notify ("left_volume");
}
bus_volume_changed (self);

notify ("volume_db");
notify ("pan");
notify (prop);
}
}

void
BusImpl::lr_to_volume_pan (double &volume_out, double &pan_out) const
{
BseBus *self = const_cast<BusImpl*> (this)->as<BseBus*>();

// this implements constant power panning

const double total_volume = sqrt (self->left_volume * self->left_volume + self->right_volume * self->right_volume);

volume_out = bse_db_from_factor (total_volume / BSE_SQRT2, -96);

pan_out = acos (std::min (self->left_volume / total_volume, 1.0)) / M_PI * 400 - 100;
}

void
BusImpl::volume_pan_to_lr (double volume_in, double pan_in)
{
BseBus *self = const_cast<BusImpl*> (this)->as<BseBus*>();

volume_in = CLAMP (volume_in, -96, 12);
pan_in = CLAMP (pan_in, -100, 100);

// this implements constant power panning
const double vfactor = bse_db_to_factor (volume_in) * BSE_SQRT2;

pan_in = (pan_in + 100) / 400 * M_PI; /* -> [0,pi/2] */

self->left_volume = cos (pan_in) * vfactor;
self->right_volume = sin (pan_in) * vfactor;
}

double
BusImpl::volume_db() const
{
double volume, pan;
lr_to_volume_pan (volume, pan);
return volume;
}

void
BusImpl::volume_db (double val)
{
BseBus *self = as<BseBus*>();

if (val != volume_db())
{
auto prop = "volume_db";
push_property_undo (prop);

double volume, pan;

lr_to_volume_pan (volume, pan);
volume = val;
volume_pan_to_lr (volume, pan);

bus_volume_changed (self);

notify ("left_volume");
notify ("right_volume");
notify ("pan");
notify (prop);
}
}

double
BusImpl::pan() const
{
double volume, pan;
lr_to_volume_pan (volume, pan);
return pan;
}

void
BusImpl::pan (double val)
{
BseBus *self = as<BseBus*>();

if (val != pan())
{
auto prop = "pan";
push_property_undo (prop);

double volume, pan;

lr_to_volume_pan (volume, pan);
pan = val;
volume_pan_to_lr (volume, pan);

bus_volume_changed (self);

notify ("left_volume");
notify ("right_volume");
notify ("volume_db");
notify (prop);
}
}
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8 changes: 8 additions & 0 deletions bse/bsebus.hh
View file
Expand Up @@ -78,6 +78,10 @@ namespace Bse {
class BusImpl : public SubSynthImpl, public virtual BusIface {
protected:
virtual ~BusImpl ();

void lr_to_volume_pan (double &volume_out, double &pan_out) const;
void volume_pan_to_lr (double volume_in, double pan_in);

public:
explicit BusImpl (BseObject*);
virtual bool mute () const override;
Expand All @@ -90,6 +94,10 @@ public:
virtual void left_volume (double val) override;
virtual double right_volume () const override;
virtual void right_volume (double val) override;
virtual double volume_db () const override;
virtual void volume_db (double val) override;
virtual double pan () const override;
virtual void pan (double val) override;
virtual bool master_output () const override;
virtual void master_output (bool val) override;
virtual Error ensure_output () override;
Expand Down

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