Do not clamp LV2 output values under normal circunstances

Only clamp outputs if plugin includes supportsStrictBounds feature,
and an output port does not set hasStrictBounds.
That case means the plugin needs strict bounds support from the host,
and does not set bounds for a port.

In the case of an output port with hasStrictBounds,
it's considered an error if the value is not really in bounds.
We won't check for this though (err, moo moo...).

Fixes #383

source/backend/plugin/CarlaPluginLV2.cpp

@@ -501,9 +501,10 @@ public:
           fCvOutBuffers(nullptr),
           fParamBuffers(nullptr),
           fCanInit2(true),
+          fNeedsFixedBuffers(false),
           fNeedsUiClose(false),
           fLatencyIndex(-1),
-          fNeedsFixedBuffers(false),
+          fStrictBounds(-1),
           fAtomBufferIn(),
           fAtomBufferOut(),
           fAtomForge(),
@@ -842,8 +843,16 @@ public:
         CARLA_SAFE_ASSERT_RETURN(fParamBuffers != nullptr, 0.0f);
         CARLA_SAFE_ASSERT_RETURN(parameterId < pData->param.count, 0.0f);
 
-        if (pData->param.data[parameterId].hints & PARAMETER_IS_STRICT_BOUNDS)
-            pData->param.ranges[parameterId].fixValue(fParamBuffers[parameterId]);
+        if (pData->param.data[parameterId].type == PARAMETER_INPUT)
+        {
+            if (pData->param.data[parameterId].hints & PARAMETER_IS_STRICT_BOUNDS)
+                pData->param.ranges[parameterId].fixValue(fParamBuffers[parameterId]);
+        }
+        else
+        {
+            if (fStrictBounds >= 0 && (pData->param.data[parameterId].hints & PARAMETER_IS_STRICT_BOUNDS) == 0)
+                pData->param.ranges[parameterId].fixValue(fParamBuffers[parameterId]);
+        }
 
         return fParamBuffers[parameterId];
     }
@@ -3451,7 +3460,9 @@ public:
                 if (pData->param.data[k].type != PARAMETER_OUTPUT)
                     continue;
 
-                pData->param.ranges[k].fixValue(fParamBuffers[k]);
+                if (fStrictBounds >= 0 && (pData->param.data[k].hints & PARAMETER_IS_STRICT_BOUNDS) != 0)
+                    // plugin is responsible to ensure correct bounds
+                    pData->param.ranges[k].fixValue(fParamBuffers[k]);
 
                 if (pData->param.data[k].midiCC > 0)
                 {
@@ -4808,6 +4819,10 @@ public:
             {
                 fNeedsFixedBuffers = true;
             }
+            else if (std::strcmp(feature.URI, LV2_PORT_PROPS__supportsStrictBounds) == 0)
+            {
+                fStrictBounds = feature.Required ? 1 : 0;
+            }
             else if (feature.Required && ! is_lv2_feature_supported(feature.URI))
             {
                 CarlaString msg("Plugin wants a feature that is not supported:\n");
@@ -5529,9 +5544,10 @@ private:
     float*  fParamBuffers;
 
     bool    fCanInit2; // some plugins don't like 2 instances
+    bool    fNeedsFixedBuffers;
     bool    fNeedsUiClose;
     int32_t fLatencyIndex; // -1 if invalid
-    bool    fNeedsFixedBuffers;
+    int     fStrictBounds; // -1 unsupported, 0 optional, 1 required
 
     Lv2AtomRingBuffer fAtomBufferIn;
     Lv2AtomRingBuffer fAtomBufferOut;