diff --git a/cscore.gradle b/cscore.gradle
index 1b79e2227f..56e4611bec 100644
--- a/cscore.gradle
+++ b/cscore.gradle
@@ -120,6 +120,29 @@ def cscoreSetupExamplesModel = { project ->
                     }
                 }
             }
+
+            settings(NativeExecutableSpec) {
+                if (project.isArm) {
+                    targetPlatform 'arm'
+                } else {
+                    //targetPlatform 'x86'
+                    targetPlatform 'x64'
+                }
+                setupDefines(project, binaries)
+                sources {
+                    cpp {
+                        source {
+                            srcDir "${rootDir}/examples/settings"
+                            include '**/*.cpp'
+                        }
+                        exportedHeaders {
+                            srcDirs = ["${rootDir}/include", "${rootDir}/wpiutil/include", project.openCvInclude]
+                            include '**/*.h'
+                        }
+                        lib library: 'cscore', linkage: 'static'
+                    }
+                }
+            }
         }
     }
 }
diff --git a/examples/settings/settings.cpp b/examples/settings/settings.cpp
new file mode 100644
index 0000000000..ef3bc420f7
--- /dev/null
+++ b/examples/settings/settings.cpp
@@ -0,0 +1,95 @@
+#include <chrono>
+#include <thread>
+
+#include "cscore.h"
+
+#include "llvm/SmallString.h"
+#include "llvm/raw_ostream.h"
+
+int main(int argc, char** argv) {
+  if (argc < 2) {
+    llvm::errs() << "Usage: settings camera [prop val] ... -- [prop val]...\n";
+    llvm::errs() << "  Example: settings 1 brightness 30 raw_contrast 10\n";
+    return 1;
+  }
+
+  int id;
+  if (llvm::StringRef{argv[1]}.getAsInteger(10, id)) {
+    llvm::errs() << "Expected number for camera\n";
+    return 2;
+  }
+
+  cs::UsbCamera camera{"usbcam", id};
+
+  // Set prior to connect
+  int arg = 2;
+  llvm::StringRef propName;
+  for (; arg < argc && llvm::StringRef{argv[arg]} != "--"; ++arg) {
+    if (propName.empty())
+      propName = argv[arg];
+    else {
+      llvm::StringRef propVal{argv[arg]};
+      int intVal;
+      if (propVal.getAsInteger(10, intVal))
+        camera.GetProperty(propName).SetString(propVal);
+      else
+        camera.GetProperty(propName).Set(intVal);
+      propName = llvm::StringRef{};
+    }
+  }
+  if (llvm::StringRef{argv[arg]} == "--") ++arg;
+
+  // Wait to connect
+  while (!camera.IsConnected())
+    std::this_thread::sleep_for(std::chrono::milliseconds(10));
+
+  // Set rest
+  propName = llvm::StringRef{};
+  for (; arg < argc; ++arg) {
+    if (propName.empty())
+      propName = argv[arg];
+    else {
+      llvm::StringRef propVal{argv[arg]};
+      int intVal;
+      if (propVal.getAsInteger(10, intVal))
+        camera.GetProperty(propName).SetString(propVal);
+      else
+        camera.GetProperty(propName).Set(intVal);
+      propName = llvm::StringRef{};
+    }
+  }
+
+  // Print settings
+  llvm::SmallString<64> buf;
+  llvm::outs() << "Properties:\n";
+  for (const auto& prop : camera.EnumerateProperties()) {
+    llvm::outs() << "  " << prop.GetName();
+    switch (prop.GetKind()) {
+      case cs::VideoProperty::kBoolean:
+        llvm::outs() << " (bool): " << "value=" << prop.Get()
+                     << " default=" << prop.GetDefault();
+        break;
+      case cs::VideoProperty::kInteger:
+        llvm::outs() << " (int): "
+                     << "value=" << prop.Get() << " min=" << prop.GetMin()
+                     << " max=" << prop.GetMax() << " step=" << prop.GetStep()
+                     << " default=" << prop.GetDefault();
+        break;
+      case cs::VideoProperty::kString:
+        llvm::outs() << " (string): " << prop.GetString(buf);
+        break;
+      case cs::VideoProperty::kEnum: {
+        llvm::outs() << " (enum): " << "value=" << prop.Get();
+        auto choices = prop.GetChoices();
+        for (size_t i = 0; i < choices.size(); ++i) {
+          if (choices[i].empty()) continue;
+          llvm::outs() << "\n    " << i << ": " << choices[i];
+        }
+        break;
+      }
+      default:
+        break;
+    }
+    llvm::outs() << '\n';
+  }
+}
diff --git a/src/CvSourceImpl.cpp b/src/CvSourceImpl.cpp
index d1911c37fc..0cf48f4ca4 100644
--- a/src/CvSourceImpl.cpp
+++ b/src/CvSourceImpl.cpp
@@ -30,6 +30,11 @@ CvSourceImpl::~CvSourceImpl() {}
 
 void CvSourceImpl::Start() {}
 
+std::unique_ptr<SourceImpl::PropertyBase> CvSourceImpl::CreateEmptyProperty(
+    llvm::StringRef name) const {
+  return llvm::make_unique<PropertyData>(name);
+}
+
 bool CvSourceImpl::CacheProperties(CS_Status* status) const {
   // Doesn't need to do anything.
   m_properties_cached = true;
@@ -43,15 +48,20 @@ void CvSourceImpl::SetProperty(int property, int value, CS_Status* status) {
     *status = CS_INVALID_PROPERTY;
     return;
   }
+
+  // Guess it's integer if we've set before get
+  if (prop->propKind == CS_PROP_NONE) prop->propKind = CS_PROP_INTEGER;
+
   if ((prop->propKind & (CS_PROP_BOOLEAN | CS_PROP_INTEGER | CS_PROP_ENUM)) ==
       0) {
     *status = CS_WRONG_PROPERTY_TYPE;
     return;
   }
-  prop->value = value;
-  Notifier::GetInstance().NotifySourceProperty(
-      *this, CS_SOURCE_PROPERTY_VALUE_UPDATED, property, prop->propKind,
-      prop->value, prop->valueStr);
+  prop->SetValue(value);
+  if (m_properties_cached)
+    Notifier::GetInstance().NotifySourceProperty(
+        *this, CS_SOURCE_PROPERTY_VALUE_UPDATED, property, prop->propKind,
+        prop->value, prop->valueStr);
 }
 
 void CvSourceImpl::SetStringProperty(int property, llvm::StringRef value,
@@ -62,14 +72,19 @@ void CvSourceImpl::SetStringProperty(int property, llvm::StringRef value,
     *status = CS_INVALID_PROPERTY;
     return;
   }
+
+  // Guess it's string if we've set before get
+  if (prop->propKind == CS_PROP_NONE) prop->propKind = CS_PROP_STRING;
+
   if (prop->propKind != CS_PROP_STRING) {
     *status = CS_WRONG_PROPERTY_TYPE;
     return;
   }
-  prop->valueStr = value;
-  Notifier::GetInstance().NotifySourceProperty(
-      *this, CS_SOURCE_PROPERTY_VALUE_UPDATED, property, CS_PROP_STRING,
-      prop->value, prop->valueStr);
+  prop->SetValue(value);
+  if (m_properties_cached)
+    Notifier::GetInstance().NotifySourceProperty(
+        *this, CS_SOURCE_PROPERTY_VALUE_UPDATED, property, CS_PROP_STRING,
+        prop->value, prop->valueStr);
 }
 
 bool CvSourceImpl::SetVideoMode(const VideoMode& mode, CS_Status* status) {
diff --git a/src/CvSourceImpl.h b/src/CvSourceImpl.h
index 166afa566e..d9e9535e46 100644
--- a/src/CvSourceImpl.h
+++ b/src/CvSourceImpl.h
@@ -48,16 +48,24 @@ class CvSourceImpl : public SourceImpl {
   class PropertyData : public PropertyBase {
    public:
     PropertyData() = default;
+    PropertyData(llvm::StringRef name_) : PropertyBase{name_} {}
     PropertyData(llvm::StringRef name_, CS_PropertyKind kind_, int minimum_,
                  int maximum_, int step_, int defaultValue_, int value_)
-        : PropertyBase{name_, kind_,         minimum_, maximum_,
-                       step_, defaultValue_, value_} {}
+        : PropertyBase{name_, kind_, step_, defaultValue_, value_} {
+      hasMinimum = true;
+      minimum = minimum_;
+      hasMaximum = true;
+      maximum = maximum_;
+    }
     ~PropertyData() override = default;
 
     std::function<void(CS_Property property)> onChange;
   };
 
  protected:
+  std::unique_ptr<PropertyBase> CreateEmptyProperty(
+      llvm::StringRef name) const override;
+
   bool CacheProperties(CS_Status* status) const override;
 
  private:
diff --git a/src/SourceImpl.cpp b/src/SourceImpl.cpp
index effabe4186..824ec0b2f1 100644
--- a/src/SourceImpl.cpp
+++ b/src/SourceImpl.cpp
@@ -90,7 +90,7 @@ int SourceImpl::GetPropertyIndex(llvm::StringRef name) const {
   if (ndx == 0) {
     // create a new index
     ndx = m_propertyData.size() + 1;
-    m_propertyData.emplace_back();
+    m_propertyData.emplace_back(CreateEmptyProperty(name));
   }
   return ndx;
 }
diff --git a/src/SourceImpl.h b/src/SourceImpl.h
index 0d0e87d2a5..4f8ff9e4b2 100644
--- a/src/SourceImpl.h
+++ b/src/SourceImpl.h
@@ -139,12 +139,11 @@ class SourceImpl {
   class PropertyBase {
    public:
     PropertyBase() = default;
-    PropertyBase(llvm::StringRef name_, CS_PropertyKind kind_, int minimum_,
-                 int maximum_, int step_, int defaultValue_, int value_)
+    PropertyBase(llvm::StringRef name_) : name{name_} {}
+    PropertyBase(llvm::StringRef name_, CS_PropertyKind kind_, int step_,
+                 int defaultValue_, int value_)
         : name{name_},
           propKind{kind_},
-          minimum{minimum_},
-          maximum{maximum_},
           step{step_},
           defaultValue{defaultValue_},
           value{value_} {}
@@ -152,12 +151,38 @@ class SourceImpl {
     PropertyBase(const PropertyBase& oth) = delete;
     PropertyBase& operator=(const PropertyBase& oth) = delete;
 
+    void SetValue(int v) {
+      if (hasMinimum && v < minimum)
+        value = minimum;
+      else if (hasMaximum && v > maximum)
+        value = maximum;
+      else
+        value = v;
+      valueSet = true;
+    }
+
+    void SetValue(llvm::StringRef v) {
+      valueStr = v;
+      valueSet = true;
+    }
+
+    void SetDefaultValue(int v) {
+      if (hasMinimum && v < minimum)
+        defaultValue = minimum;
+      else if (hasMaximum && v > maximum)
+        defaultValue = maximum;
+      else
+        defaultValue = v;
+    }
+
     std::string name;
     CS_PropertyKind propKind{CS_PROP_NONE};
-    int minimum;
-    int maximum;
-    int step;
-    int defaultValue;
+    bool hasMinimum{false};
+    bool hasMaximum{false};
+    int minimum{0};
+    int maximum{100};
+    int step{1};
+    int defaultValue{0};
     int value{0};
     std::string valueStr;
     std::vector<std::string> enumChoices;
@@ -176,6 +201,12 @@ class SourceImpl {
     return m_propertyData[property - 1].get();
   }
 
+  // Create an "empty" property.  This is called by GetPropertyIndex to create
+  // properties that don't exist (as GetPropertyIndex can't fail).
+  // Note: called with m_mutex held.
+  virtual std::unique_ptr<PropertyBase> CreateEmptyProperty(
+      llvm::StringRef name) const = 0;
+
   // Cache properties.  Implementations must return false and set status to
   // CS_SOURCE_IS_DISCONNECTED if not possible to cache.
   virtual bool CacheProperties(CS_Status* status) const = 0;
diff --git a/src/UsbCameraImpl.cpp b/src/UsbCameraImpl.cpp
index c34753f646..9149eef5a9 100644
--- a/src/UsbCameraImpl.cpp
+++ b/src/UsbCameraImpl.cpp
@@ -57,19 +57,37 @@ static inline struct v4l2_fract FPSToFract(int fps) {
 }
 
 // Conversion from v4l2_format pixelformat to VideoMode::PixelFormat
-static VideoMode::PixelFormat ToPixelFormat(__u32 pixelformat) {
-  switch (pixelformat) {
+static VideoMode::PixelFormat ToPixelFormat(__u32 pixelFormat) {
+  switch (pixelFormat) {
     case V4L2_PIX_FMT_MJPEG:
       return VideoMode::kMJPEG;
     case V4L2_PIX_FMT_YUYV:
       return VideoMode::kYUYV;
     case V4L2_PIX_FMT_RGB565:
       return VideoMode::kRGB565;
+    case V4L2_PIX_FMT_BGR24:
+      return VideoMode::kBGR;
     default:
       return VideoMode::kUnknown;
   }
 }
 
+// Conversion from VideoMode::PixelFormat to v4l2_format pixelformat
+static __u32 FromPixelFormat(VideoMode::PixelFormat pixelFormat) {
+  switch (pixelFormat) {
+    case VideoMode::kMJPEG:
+      return V4L2_PIX_FMT_MJPEG;
+    case VideoMode::kYUYV:
+      return V4L2_PIX_FMT_YUYV;
+    case VideoMode::kRGB565:
+      return V4L2_PIX_FMT_RGB565;
+    case VideoMode::kBGR:
+      return V4L2_PIX_FMT_BGR24;
+    default:
+      return 0;
+  }
+}
+
 // Removes non-alphanumeric characters and replaces spaces with underscores.
 // e.g. "Zoom, Absolute" -> "zoom_absolute", "Pan (Absolute)" -> "pan_absolute"
 static llvm::StringRef NormalizeName(llvm::StringRef name,
@@ -86,13 +104,53 @@ static llvm::StringRef NormalizeName(llvm::StringRef name,
   return llvm::StringRef(buf.data(), buf.size());
 }
 
+static bool IsPercentageProperty(llvm::StringRef name) {
+  if (name.startswith("raw_")) name = name.substr(4);
+  return name == "brightness" || name == "contrast" || name == "saturation" ||
+         name == "hue" || name == "sharpness" || name == "gain" ||
+         name == "exposure_absolute";
+}
+
+int UsbCameraImpl::RawToPercentage(const PropertyData& rawProp, int rawValue) {
+  return 100.0 * (rawValue - rawProp.minimum) /
+         (rawProp.maximum - rawProp.minimum);
+}
+
+int UsbCameraImpl::PercentageToRaw(const PropertyData& rawProp,
+                                   int percentValue) {
+  return rawProp.minimum +
+         (rawProp.maximum - rawProp.minimum) * (percentValue / 100.0);
+}
+
+void UsbCameraImpl::UpdatePropertyValue(int property, bool setString, int value,
+                                        llvm::StringRef valueStr) {
+  auto prop = static_cast<PropertyData*>(GetProperty(property));
+  if (!prop) return;
+
+  if (setString)
+    prop->SetValue(valueStr);
+  else
+    prop->SetValue(value);
+
+  // Only notify updates after we've notified created
+  if (m_properties_cached)
+    Notifier::GetInstance().NotifySourceProperty(
+        *this, CS_SOURCE_PROPERTY_VALUE_UPDATED, property, prop->propKind,
+        prop->value, prop->valueStr);
+}
+
 #ifdef VIDIOC_QUERY_EXT_CTRL
 UsbCameraImpl::PropertyData::PropertyData(
     const struct v4l2_query_ext_ctrl& ctrl)
-    : PropertyBase(llvm::StringRef{}, CS_PROP_NONE, ctrl.minimum, ctrl.maximum,
-                   ctrl.step, ctrl.default_value, 0),
+    : PropertyBase(llvm::StringRef{}, CS_PROP_NONE, ctrl.step,
+                   ctrl.default_value, 0),
       id(ctrl.id & V4L2_CTRL_ID_MASK),
       type(ctrl.type) {
+  hasMinimum = true;
+  minimum = ctrl.minimum;
+  hasMaximum = true;
+  maximum = ctrl.maximum;
+
   // propKind
   switch (ctrl.type) {
     case V4L2_CTRL_TYPE_INTEGER:
@@ -122,10 +180,15 @@ UsbCameraImpl::PropertyData::PropertyData(
 #endif
 
 UsbCameraImpl::PropertyData::PropertyData(const struct v4l2_queryctrl& ctrl)
-    : PropertyBase(llvm::StringRef{}, CS_PROP_NONE, ctrl.minimum, ctrl.maximum,
-                   ctrl.step, ctrl.default_value, 0),
+    : PropertyBase(llvm::StringRef{}, CS_PROP_NONE, ctrl.step,
+                   ctrl.default_value, 0),
       id(ctrl.id & V4L2_CTRL_ID_MASK),
       type(ctrl.type) {
+  hasMinimum = true;
+  minimum = ctrl.minimum;
+  hasMaximum = true;
+  maximum = ctrl.maximum;
+
   // propKind
   switch (ctrl.type) {
     case V4L2_CTRL_TYPE_INTEGER:
@@ -647,9 +710,10 @@ void UsbCameraImpl::DeviceConnect() {
     SDEBUG3("restoring settings");
     std::unique_lock<std::mutex> lock2(m_mutex);
     for (std::size_t i = 0; i < m_propertyData.size(); ++i) {
-      const auto& prop = m_propertyData[i];
-      if (!prop || !prop->valueSet) continue;
-      if (!DeviceSetProperty(lock2, static_cast<const PropertyData&>(*prop)))
+      const auto prop =
+          static_cast<const PropertyData*>(m_propertyData[i].get());
+      if (!prop || !prop->valueSet || prop->percentage) continue;
+      if (!DeviceSetProperty(lock2, *prop))
         SWARNING("failed to set property " << prop->name);
     }
   }
@@ -820,66 +884,17 @@ void UsbCameraImpl::DeviceProcessCommands() {
       }
     } else if (msg->kind == Message::kCmdSetProperty ||
                msg->kind == Message::kCmdSetPropertyStr) {
+      bool setString = (msg->kind == Message::kCmdSetPropertyStr);
       int property = msg->data[0];
-
-      // Look up
-      auto prop = static_cast<PropertyData*>(GetProperty(property));
-      if (!prop) {
+      int value = msg->data[1];
+      CS_StatusValue status =
+          DeviceCmdSetProperty(lock, property, setString, value, msg->dataStr);
+      if (status == CS_OK) {
+        msg->kind = Message::kOk;
+      } else {
         msg->kind = Message::kError;
-        msg->data[0] = CS_INVALID_PROPERTY;
-        goto done;
+        msg->data[0] = status;
       }
-
-      // Check kind match
-      if ((msg->kind == Message::kCmdSetPropertyStr &&
-           prop->propKind != CS_PROP_STRING) ||
-          (msg->kind == Message::kCmdSetProperty &&
-           (prop->propKind &
-            (CS_PROP_BOOLEAN | CS_PROP_INTEGER | CS_PROP_ENUM)) == 0)) {
-        msg->kind = Message::kError;
-        msg->data[0] = CS_WRONG_PROPERTY_TYPE;
-        goto done;
-      }
-
-      // If we're connected...
-      int fd = m_fd.load();
-      if (fd >= 0) {
-        // Get into local variables before we release the lock
-        int rv;
-        unsigned id = prop->id;
-        int maximum = prop->maximum;
-        int type = prop->type;
-
-        // Set the property value on the device
-        lock.unlock();
-        if (msg->kind == Message::kCmdSetPropertyStr)
-          rv = SetStringCtrlIoctl(fd, id, maximum, msg->dataStr);
-        else
-          rv =
-              SetIntCtrlIoctl(fd, id, type, static_cast<int64_t>(msg->data[1]));
-        lock.lock();
-
-        if (rv < 0) {
-          msg->kind = Message::kError;
-          msg->data[0] = CS_PROPERTY_WRITE_FAILED;
-          goto done;
-        }
-      }
-
-      // Cache the set value.  We need to re-get the pointer due to
-      // releasing the lock.
-      prop = static_cast<PropertyData*>(GetProperty(property));
-      if (msg->kind == Message::kCmdSetPropertyStr)
-        prop->valueStr = msg->dataStr;
-      else
-        prop->value = msg->data[1];
-      prop->valueSet = true;
-      // Only notify updates after we've notified created
-      if (m_properties_cached)
-        Notifier::GetInstance().NotifySourceProperty(
-            *this, CS_SOURCE_PROPERTY_VALUE_UPDATED, property, prop->propKind,
-            prop->value, prop->valueStr);
-      msg->kind = Message::kOk;
     } else if (msg->kind == Message::kNumSinksChanged ||
                msg->kind == Message::kNumSinksEnabledChanged) {
       // These are send-only messages, so recycle here.  DestroyMessage needs
@@ -893,7 +908,6 @@ void UsbCameraImpl::DeviceProcessCommands() {
       msg->kind = Message::kNone;
     }
 
-done:
     if (msg) m_responses.emplace_back(std::move(msg));
   }
   lock.unlock();
@@ -912,21 +926,12 @@ void UsbCameraImpl::DeviceSetMode() {
                           : 0;
 #endif
   vfmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
-  switch (m_mode.pixelFormat) {
-    case VideoMode::kMJPEG:
-      vfmt.fmt.pix.pixelformat = V4L2_PIX_FMT_MJPEG;
-      break;
-    case VideoMode::kYUYV:
-      vfmt.fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV;
-      break;
-    case VideoMode::kRGB565:
-      vfmt.fmt.pix.pixelformat = V4L2_PIX_FMT_RGB565;
-      break;
-    default:
-      SWARNING("could not set format " << m_mode.pixelFormat
-                                       << ", defaulting to MJPEG");
-      vfmt.fmt.pix.pixelformat = V4L2_PIX_FMT_MJPEG;
-      break;
+  vfmt.fmt.pix.pixelformat =
+      FromPixelFormat(static_cast<VideoMode::PixelFormat>(m_mode.pixelFormat));
+  if (vfmt.fmt.pix.pixelformat == 0) {
+    SWARNING("could not set format " << m_mode.pixelFormat
+                                     << ", defaulting to MJPEG");
+    vfmt.fmt.pix.pixelformat = V4L2_PIX_FMT_MJPEG;
   }
   vfmt.fmt.pix.width = m_mode.width;
   vfmt.fmt.pix.height = m_mode.height;
@@ -977,21 +982,7 @@ void UsbCameraImpl::DeviceCacheMode() {
     m_mode = VideoMode{VideoMode::kMJPEG, 320, 240, 30};
     return;
   }
-  VideoMode::PixelFormat pixelFormat;
-  switch (vfmt.fmt.pix.pixelformat) {
-    case V4L2_PIX_FMT_MJPEG:
-      pixelFormat = VideoMode::kMJPEG;
-      break;
-    case V4L2_PIX_FMT_YUYV:
-      pixelFormat = VideoMode::kYUYV;
-      break;
-    case V4L2_PIX_FMT_RGB565:
-      pixelFormat = VideoMode::kRGB565;
-      break;
-    default:
-      pixelFormat = VideoMode::kUnknown;
-      break;
-  }
+  VideoMode::PixelFormat pixelFormat = ToPixelFormat(vfmt.fmt.pix.pixelformat);
   int width = vfmt.fmt.pix.width;
   int height = vfmt.fmt.pix.height;
 
@@ -1066,49 +1057,118 @@ void UsbCameraImpl::DeviceCacheMode() {
   Notifier::GetInstance().NotifySource(*this, CS_SOURCE_VIDEOMODE_CHANGED);
 }
 
-void UsbCameraImpl::DeviceCacheProperty(std::unique_ptr<PropertyData> prop) {
-  std::unique_lock<std::mutex> lock(m_mutex);
-  int& ndx = m_properties[prop->name];
-  if (ndx == 0) {
-    // get the value
-    lock.unlock();
-    if (!DeviceGetProperty(prop.get()))
-      SWARNING("failed to get property " << prop->name);
-    lock.lock();
-    // create a new index
-    ndx = m_propertyData.size() + 1;
-    m_propertyData.emplace_back(std::move(prop));
-  } else {
-    // merge with existing settings
-    auto prop2 = static_cast<PropertyData*>(GetProperty(ndx));
-    prop->valueSet = prop2->valueSet;
-    prop->value = prop2->value;
-    prop->valueStr = std::move(prop2->valueStr);
-    lock.unlock();
-    if (prop->valueSet) {
-      // set the value if it was previously set
-      if (!DeviceSetProperty(lock, *prop))
-        SWARNING("failed to set property " << prop->name);
-    } else {
-      // otherwise get the value
-      if (!DeviceGetProperty(prop.get()))
-        SWARNING("failed to get property " << prop->name);
-    }
-    lock.lock();
-    m_propertyData[ndx - 1] = std::move(prop);
-  }
-  auto eventProp = static_cast<PropertyData*>(GetProperty(ndx));
+void UsbCameraImpl::NotifyPropertyCreated(int propIndex, PropertyData& prop) {
   auto& notifier = Notifier::GetInstance();
-  notifier.NotifySourceProperty(*this, CS_SOURCE_PROPERTY_CREATED, ndx,
-                                eventProp->propKind, eventProp->value,
-                                eventProp->valueStr);
+  notifier.NotifySourceProperty(*this, CS_SOURCE_PROPERTY_CREATED, propIndex,
+                                prop.propKind, prop.value, prop.valueStr);
   // also notify choices updated event for enum types
-  if (eventProp->propKind == CS_PROP_ENUM)
+  if (prop.propKind == CS_PROP_ENUM)
     notifier.NotifySourceProperty(*this, CS_SOURCE_PROPERTY_CHOICES_UPDATED,
-                                  ndx, eventProp->propKind, eventProp->value,
+                                  propIndex, prop.propKind, prop.value,
                                   llvm::StringRef{});
 }
 
+void UsbCameraImpl::DeviceCacheProperty(std::unique_ptr<PropertyData> rawProp) {
+  // For percentage properties, we want to cache both the raw and the
+  // percentage versions.  This function is always called with prop being
+  // the raw property (as it's coming from the camera) so if required, we need
+  // to rename this one as well as create/cache the percentage version.
+  //
+  // This is complicated by the fact that either the percentage version or the
+  // the raw version may have been set previously.  If both were previously set,
+  // the raw version wins.
+  std::unique_ptr<PropertyData> perProp;
+  if (IsPercentageProperty(rawProp->name)) {
+    perProp = llvm::make_unique<PropertyData>(rawProp->name, 0, *rawProp, 0, 0);
+    rawProp->name = "raw_" + perProp->name;
+  }
+
+  std::unique_lock<std::mutex> lock(m_mutex);
+  int* rawIndex = &m_properties[rawProp->name];
+  bool newRaw = *rawIndex == 0;
+  PropertyData* oldRawProp =
+      newRaw ? nullptr : static_cast<PropertyData*>(GetProperty(*rawIndex));
+
+  int* perIndex = perProp ? &m_properties[perProp->name] : nullptr;
+  bool newPer = !perIndex || *perIndex == 0;
+  PropertyData* oldPerProp =
+      newPer ? nullptr : static_cast<PropertyData*>(GetProperty(*perIndex));
+
+  if (oldRawProp && oldRawProp->valueSet) {
+    // Merge existing raw setting and set percentage from it
+    rawProp->SetValue(oldRawProp->value);
+    rawProp->valueStr = std::move(oldRawProp->valueStr);
+
+    if (perProp) {
+      perProp->SetValue(RawToPercentage(*rawProp, rawProp->value));
+      perProp->valueStr = rawProp->valueStr;  // copy
+    }
+  } else if (oldPerProp && oldPerProp->valueSet) {
+    // Merge existing percentage setting and set raw from it
+    perProp->SetValue(oldPerProp->value);
+    perProp->valueStr = std::move(oldPerProp->valueStr);
+
+    rawProp->SetValue(PercentageToRaw(*rawProp, perProp->value));
+    rawProp->valueStr = perProp->valueStr;  // copy
+  } else {
+    // Read current raw value and set percentage from it
+    lock.unlock();
+    if (!DeviceGetProperty(rawProp.get()))
+      SWARNING("failed to get property " << rawProp->name);
+    lock.lock();
+
+    if (perProp) {
+      perProp->SetValue(RawToPercentage(*rawProp, rawProp->value));
+      perProp->valueStr = rawProp->valueStr;  // copy
+    }
+  }
+
+  // Set value on device if user-configured
+  if (rawProp->valueSet) {
+    if (!DeviceSetProperty(lock, *rawProp))
+      SWARNING("failed to set property " << rawProp->name);
+  }
+
+  // Update pointers since we released the lock
+  rawIndex = &m_properties[rawProp->name];
+  perIndex = perProp ? &m_properties[perProp->name] : nullptr;
+
+  // Get pointers before we move the std::unique_ptr values
+  auto rawPropPtr = rawProp.get();
+  auto perPropPtr = perProp.get();
+
+  if (newRaw) {
+    // create a new index
+    *rawIndex = m_propertyData.size() + 1;
+    m_propertyData.emplace_back(std::move(rawProp));
+  } else {
+    // update
+    m_propertyData[*rawIndex - 1] = std::move(rawProp);
+  }
+
+  // Finish setting up percentage property
+  if (perProp) {
+    perProp->propPair = *rawIndex;
+    perProp->defaultValue =
+        RawToPercentage(*rawPropPtr, rawPropPtr->defaultValue);
+
+    if (newPer) {
+      // create a new index
+      *perIndex = m_propertyData.size() + 1;
+      m_propertyData.emplace_back(std::move(perProp));
+    } else if (perIndex) {
+      // update
+      m_propertyData[*perIndex - 1] = std::move(perProp);
+    }
+
+    // Tell raw property where to find percentage property
+    rawPropPtr->propPair = *perIndex;
+  }
+
+  NotifyPropertyCreated(*rawIndex, *rawPropPtr);
+  if (perPropPtr) NotifyPropertyCreated(*perIndex, *perPropPtr);
+}
+
 void UsbCameraImpl::DeviceCacheProperties() {
   int fd = m_fd.load();
   if (fd < 0) return;
@@ -1213,6 +1273,14 @@ bool UsbCameraImpl::DeviceGetProperty(PropertyData* prop) {
 
 bool UsbCameraImpl::DeviceSetProperty(std::unique_lock<std::mutex>& lock,
                                       const PropertyData& prop) {
+  // Make a copy of the string as we're about to release the lock
+  llvm::SmallString<128> valueStr{prop.valueStr};
+  return DeviceSetProperty(lock, prop, prop.value, valueStr);
+}
+
+bool UsbCameraImpl::DeviceSetProperty(std::unique_lock<std::mutex>& lock,
+                                      const PropertyData& prop, int value,
+                                      llvm::StringRef valueStr) {
   int fd = m_fd.load();
   if (fd < 0) return true;
   unsigned id = prop.id;
@@ -1224,7 +1292,6 @@ bool UsbCameraImpl::DeviceSetProperty(std::unique_lock<std::mutex>& lock,
     case CS_PROP_ENUM:
       {
         int type = prop.type;
-        int value = prop.value;
         lock.unlock();
         rv = SetIntCtrlIoctl(fd, id, type, value);
         lock.lock();
@@ -1233,7 +1300,6 @@ bool UsbCameraImpl::DeviceSetProperty(std::unique_lock<std::mutex>& lock,
     case CS_PROP_STRING:
       {
         int maximum = prop.maximum;
-        llvm::SmallString<128> valueStr{prop.valueStr};
         lock.unlock();
         rv = SetStringCtrlIoctl(fd, id, maximum, valueStr);
         lock.lock();
@@ -1246,6 +1312,54 @@ bool UsbCameraImpl::DeviceSetProperty(std::unique_lock<std::mutex>& lock,
   return rv >= 0;
 }
 
+CS_StatusValue UsbCameraImpl::DeviceCmdSetProperty(
+    std::unique_lock<std::mutex>& lock, int property, bool setString, int value,
+    llvm::StringRef valueStr) {
+  // Look up
+  auto prop = static_cast<PropertyData*>(GetProperty(property));
+  if (!prop) return CS_INVALID_PROPERTY;
+
+  // If setting before we get, guess initial type based on set
+  if (prop->propKind == CS_PROP_NONE) {
+    if (setString)
+      prop->propKind = CS_PROP_STRING;
+    else
+      prop->propKind = CS_PROP_INTEGER;
+  }
+
+  // Check kind match
+  if ((setString && prop->propKind != CS_PROP_STRING) ||
+      (!setString &&
+       (prop->propKind & (CS_PROP_BOOLEAN | CS_PROP_INTEGER | CS_PROP_ENUM)) ==
+           0))
+    return CS_WRONG_PROPERTY_TYPE;
+
+  // Handle percentage property
+  int percentageProperty = prop->propPair;
+  int percentageValue = value;
+  if (percentageProperty != 0) {
+    if (prop->percentage) {
+      std::swap(percentageProperty, property);
+      prop = static_cast<PropertyData*>(GetProperty(property));
+      value = PercentageToRaw(*prop, percentageValue);
+    } else {
+      percentageValue = RawToPercentage(*prop, value);
+    }
+  }
+
+  // Actually set the new value on the device (if possible)
+  if (!DeviceSetProperty(lock, *prop, value, valueStr))
+    return CS_PROPERTY_WRITE_FAILED;
+
+  // Cache the set values
+  UpdatePropertyValue(property, setString, value, valueStr);
+  if (percentageProperty != 0)
+    UpdatePropertyValue(percentageProperty, setString, percentageValue,
+                        valueStr);
+
+  return CS_OK;
+}
+
 std::unique_ptr<UsbCameraImpl::Message> UsbCameraImpl::SendAndWait(
     std::unique_ptr<Message> msg) const {
   int fd = m_command_fd.load();
@@ -1303,6 +1417,11 @@ void UsbCameraImpl::Send(std::unique_ptr<Message> msg) const {
   eventfd_write(fd, 1);
 }
 
+std::unique_ptr<SourceImpl::PropertyBase> UsbCameraImpl::CreateEmptyProperty(
+    llvm::StringRef name) const {
+  return llvm::make_unique<PropertyData>(name);
+}
+
 bool UsbCameraImpl::CacheProperties(CS_Status* status) const {
   // Wake up camera thread; this will try to reconnect
   auto msg = CreateMessage(Message::kNone);
diff --git a/src/UsbCameraImpl.h b/src/UsbCameraImpl.h
index da44196573..01dc3644eb 100644
--- a/src/UsbCameraImpl.h
+++ b/src/UsbCameraImpl.h
@@ -53,6 +53,22 @@ class UsbCameraImpl : public SourceImpl {
   class PropertyData : public PropertyBase {
    public:
     PropertyData() = default;
+    PropertyData(llvm::StringRef name_) : PropertyBase{name_} {}
+
+    // Normalized property constructor
+    PropertyData(llvm::StringRef name_, int rawIndex_,
+                 const PropertyData& rawProp, int defaultValue_, int value_)
+        : PropertyBase(name_, rawProp.propKind, 1, defaultValue_, value_),
+          percentage{true},
+          propPair{rawIndex_},
+          id{rawProp.id},
+          type{rawProp.type} {
+      hasMinimum = true;
+      minimum = 0;
+      hasMaximum = true;
+      maximum = 100;
+    }
+
 #ifdef __linux__
 #ifdef VIDIOC_QUERY_EXT_CTRL
     PropertyData(const struct v4l2_query_ext_ctrl& ctrl);
@@ -60,8 +76,14 @@ class UsbCameraImpl : public SourceImpl {
     PropertyData(const struct v4l2_queryctrl& ctrl);
 #endif
 
-    unsigned id;  // implementation-level id
-    int type;  // implementation type, not CS_PropertyKind!
+    // If this is a percentage (rather than raw) property
+    bool percentage{false};
+
+    // If not 0, index of corresponding raw/percentage property
+    int propPair{0};
+
+    unsigned id{0};  // implementation-level id
+    int type{0};  // implementation type, not CS_PropertyKind!
   };
 
   // Messages passed to/from camera thread
@@ -89,6 +111,9 @@ class UsbCameraImpl : public SourceImpl {
   };
 
  protected:
+  std::unique_ptr<PropertyBase> CreateEmptyProperty(
+      llvm::StringRef name) const override;
+
   // Cache properties.  Immediately successful if properties are already cached.
   // If they are not, tries to connect to the camera to do so; returns false and
   // sets status to CS_SOURCE_IS_DISCONNECTED if that too fails.
@@ -126,12 +151,27 @@ class UsbCameraImpl : public SourceImpl {
   void DeviceSetMode();
   void DeviceSetFPS();
   void DeviceCacheMode();
-  void DeviceCacheProperty(std::unique_ptr<PropertyData> prop);
+  void DeviceCacheProperty(std::unique_ptr<PropertyData> rawProp);
   void DeviceCacheProperties();
   void DeviceCacheVideoModes();
   bool DeviceGetProperty(PropertyData* prop);
   bool DeviceSetProperty(std::unique_lock<std::mutex>& lock,
                          const PropertyData& prop);
+  bool DeviceSetProperty(std::unique_lock<std::mutex>& lock,
+                         const PropertyData& prop, int value,
+                         llvm::StringRef valueStr);
+
+  // Command helper functions
+  CS_StatusValue DeviceCmdSetProperty(std::unique_lock<std::mutex>& lock,
+                                      int property, bool setString, int value,
+                                      llvm::StringRef valueStr);
+
+  // Property helper functions
+  int RawToPercentage(const PropertyData& rawProp, int rawValue);
+  int PercentageToRaw(const PropertyData& rawProp, int percentValue);
+  void UpdatePropertyValue(int property, bool setString, int value,
+                           llvm::StringRef valueStr);
+  void NotifyPropertyCreated(int propIndex, PropertyData& prop);
 
   //
   // Variables only used within camera thread