Added hsv plugin with hsvfilter and hsvdetector elements

Cargo.toml

@@ -21,6 +21,7 @@ members = [
     "video/gif",
     "video/rav1e",
     "video/rspng",
+    "video/hsv",
     "text/wrap",
 ]
 

meson.build

@@ -42,6 +42,7 @@ plugins_rep = {
   'gst-plugin-textwrap': 'libgstrstextwrap',
   'gst-plugin-threadshare': 'libgstthreadshare',
   'gst-plugin-togglerecord': 'libgsttogglerecord',
+  'gst-plugin-hsv': 'libgsthsv',
 }
 
 exclude = []

video/hsv/Cargo.toml

@@ -0,0 +1,30 @@
+[package]
+name = "gst-plugin-hsv"
+version = "0.6.0"
+authors = ["Julien Bardagi <julien.bardagi@gmail.com>"]
+repository = "https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs"
+license = "MIT/Apache-2.0"
+edition = "2018"
+description = "HSV manipulation elements, written in Rust"
+
+[dependencies]
+glib = { git = "https://github.com/gtk-rs/gtk-rs" }
+gst = { package = "gstreamer", git = "https://gitlab.freedesktop.org/gstreamer/gstreamer-rs" }
+gst-base = { package = "gstreamer-base", git = "https://gitlab.freedesktop.org/gstreamer/gstreamer-rs" }
+gst-video = { package = "gstreamer-video", git = "https://gitlab.freedesktop.org/gstreamer/gstreamer-rs" }
+gst-audio = { package = "gstreamer-audio", git = "https://gitlab.freedesktop.org/gstreamer/gstreamer-rs" }
+byte-slice-cast = "1.0"
+atomic_refcell = "0.1"
+num-traits = "0.2"
+once_cell = "1.0"
+
+[dev-dependencies]
+gst_check = { package = "gstreamer-check", git = "https://gitlab.freedesktop.org/gstreamer/gstreamer-rs" }
+
+[lib]
+name = "gsthsv"
+crate-type = ["cdylib", "rlib", "staticlib"]
+path = "src/lib.rs"
+
+[build-dependencies]
+gst-plugin-version-helper = { path="../../version-helper" }

video/hsv/LICENSE-APACHE

@@ -0,0 +1,201 @@
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video/hsv/LICENSE-MIT

@@ -0,0 +1,23 @@
+Permission is hereby granted, free of charge, to any
+person obtaining a copy of this software and associated
+documentation files (the "Software"), to deal in the
+Software without restriction, including without
+limitation the rights to use, copy, modify, merge,
+publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software
+is furnished to do so, subject to the following
+conditions:
+
+The above copyright notice and this permission notice
+shall be included in all copies or substantial portions
+of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
+ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
+TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
+PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
+SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
+IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.

video/hsv/build.rs

@@ -0,0 +1,3 @@
+fn main() {
+    gst_plugin_version_helper::get_info()
+}

video/hsv/src/hsvdetector/imp.rs

@@ -0,0 +1,537 @@
+// Copyright (C) 2020 Julien Bardagi <julien.bardagi@gmail.com>
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use glib::subclass;
+use glib::subclass::prelude::*;
+use gst::prelude::*;
+use gst::subclass::prelude::*;
+
+use gst::{gst_debug, gst_info};
+use gst_base::subclass::prelude::*;
+
+use atomic_refcell::AtomicRefCell;
+use std::i32;
+use std::sync::Mutex;
+
+use once_cell::sync::Lazy;
+use std::convert::TryInto;
+
+use super::super::hsvutils;
+
+// Default values of properties
+const DEFAULT_HUE_REF: f32 = 0.0;
+const DEFAULT_HUE_VAR: f32 = 10.0;
+const DEFAULT_SATURATION_REF: f32 = 0.0;
+const DEFAULT_SATURATION_VAR: f32 = 0.15;
+const DEFAULT_VALUE_REF: f32 = 0.0;
+const DEFAULT_VALUE_VAR: f32 = 0.3;
+
+// Property value storage
+#[derive(Debug, Clone, Copy)]
+struct Settings {
+    hue_ref: f32,
+    hue_var: f32,
+    saturation_ref: f32,
+    saturation_var: f32,
+    value_ref: f32,
+    value_var: f32,
+}
+
+impl Default for Settings {
+    fn default() -> Self {
+        Settings {
+            hue_ref: DEFAULT_HUE_REF,
+            hue_var: DEFAULT_HUE_VAR,
+            saturation_ref: DEFAULT_SATURATION_REF,
+            saturation_var: DEFAULT_SATURATION_VAR,
+            value_ref: DEFAULT_VALUE_REF,
+            value_var: DEFAULT_VALUE_VAR,
+        }
+    }
+}
+
+// Metadata for the properties
+static PROPERTIES: [subclass::Property; 6] = [
+    subclass::Property("hue-ref", |name| {
+        glib::ParamSpec::float(
+            name,
+            "Hue reference",
+            "Hue reference in degrees",
+            f32::MIN,
+            f32::MAX,
+            DEFAULT_HUE_REF,
+            glib::ParamFlags::READWRITE,
+        )
+    }),
+    subclass::Property("hue-var", |name| {
+        glib::ParamSpec::float(
+            name,
+            "Hue variation",
+            "Allowed hue variation from the reference hue angle, in degrees",
+            0.0,
+            180.0,
+            DEFAULT_HUE_VAR,
+            glib::ParamFlags::READWRITE,
+        )
+    }),
+    subclass::Property("saturation-ref", |name| {
+        glib::ParamSpec::float(
+            name,
+            "Saturation reference",
+            "Reference saturation value",
+            0.0,
+            1.0,
+            DEFAULT_SATURATION_REF,
+            glib::ParamFlags::READWRITE,
+        )
+    }),
+    subclass::Property("saturation-var", |name| {
+        glib::ParamSpec::float(
+            name,
+            "Saturation variation",
+            "Allowed saturation variation from the reference value",
+            0.0,
+            1.0,
+            DEFAULT_SATURATION_VAR,
+            glib::ParamFlags::READWRITE,
+        )
+    }),
+    subclass::Property("value-ref", |name| {
+        glib::ParamSpec::float(
+            name,
+            "Value reference",
+            "Reference value value",
+            0.0,
+            1.0,
+            DEFAULT_VALUE_REF,
+            glib::ParamFlags::READWRITE,
+        )
+    }),
+    subclass::Property("value-var", |name| {
+        glib::ParamSpec::float(
+            name,
+            "Value variation",
+            "Allowed value variation from the reference value",
+            0.0,
+            1.0,
+            DEFAULT_VALUE_VAR,
+            glib::ParamFlags::READWRITE,
+        )
+    }),
+];
+
+// Stream-specific state, i.e. video format configuration
+struct State {
+    in_info: gst_video::VideoInfo,
+    out_info: gst_video::VideoInfo,
+}
+
+// Struct containing all the element data
+pub struct HsvDetector {
+    settings: Mutex<Settings>,
+    state: AtomicRefCell<Option<State>>,
+}
+
+static CAT: Lazy<gst::DebugCategory> = Lazy::new(|| {
+    gst::DebugCategory::new(
+        "hsvdetector",
+        gst::DebugColorFlags::empty(),
+        Some("Rust HSV-based detection filter"),
+    )
+});
+
+impl ObjectSubclass for HsvDetector {
+    const NAME: &'static str = "HsvDetector";
+    type Type = super::HsvDetector;
+    type ParentType = gst_base::BaseTransform;
+    type Instance = gst::subclass::ElementInstanceStruct<Self>;
+    type Class = subclass::simple::ClassStruct<Self>;
+
+    // Boilerplate macro
+    glib::object_subclass!();
+
+    // Creates a new instance.
+    fn new() -> Self {
+        Self {
+            settings: Mutex::new(Default::default()),
+            state: AtomicRefCell::new(None),
+        }
+    }
+
+    fn class_init(klass: &mut Self::Class) {
+        klass.set_metadata(
+            "HSV detector",
+            "Filter/Effect/Converter/Video",
+            "Works within the HSV colorspace to mark positive pixels",
+            "Julien Bardagi <julien.bardagi@gmail.com>",
+        );
+
+        // src pad capabilities
+        let caps = gst::Caps::new_simple(
+            "video/x-raw",
+            &[
+                (
+                    "format",
+                    &gst::List::new(&[&gst_video::VideoFormat::Rgba.to_str()]),
+                ),
+                ("width", &gst::IntRange::<i32>::new(0, i32::MAX)),
+                ("height", &gst::IntRange::<i32>::new(0, i32::MAX)),
+                (
+                    "framerate",
+                    &gst::FractionRange::new(
+                        gst::Fraction::new(0, 1),
+                        gst::Fraction::new(i32::MAX, 1),
+                    ),
+                ),
+            ],
+        );
+
+        let src_pad_template = gst::PadTemplate::new(
+            "src",
+            gst::PadDirection::Src,
+            gst::PadPresence::Always,
+            &caps,
+        )
+        .unwrap();
+        klass.add_pad_template(src_pad_template);
+
+        // sink pad capabilities
+        let caps = gst::Caps::new_simple(
+            "video/x-raw",
+            &[
+                (
+                    "format",
+                    &gst::List::new(&[&gst_video::VideoFormat::Rgbx.to_str()]),
+                ),
+                ("width", &gst::IntRange::<i32>::new(0, i32::MAX)),
+                ("height", &gst::IntRange::<i32>::new(0, i32::MAX)),
+                (
+                    "framerate",
+                    &gst::FractionRange::new(
+                        gst::Fraction::new(0, 1),
+                        gst::Fraction::new(i32::MAX, 1),
+                    ),
+                ),
+            ],
+        );
+
+        let sink_pad_template = gst::PadTemplate::new(
+            "sink",
+            gst::PadDirection::Sink,
+            gst::PadPresence::Always,
+            &caps,
+        )
+        .unwrap();
+        klass.add_pad_template(sink_pad_template);
+
+        // Install all our properties
+        klass.install_properties(&PROPERTIES);
+
+        klass.configure(
+            gst_base::subclass::BaseTransformMode::NeverInPlace,
+            false,
+            false,
+        );
+    }
+}
+
+impl ObjectImpl for HsvDetector {
+    fn set_property(&self, obj: &Self::Type, id: usize, value: &glib::Value) {
+        let prop = &PROPERTIES[id];
+
+        match *prop {
+            subclass::Property("hue-ref", ..) => {
+                let mut settings = self.settings.lock().unwrap();
+                let hue_ref = value.get_some().expect("type checked upstream");
+                gst_info!(
+                    CAT,
+                    obj: obj,
+                    "Changing hue-ref from {} to {}",
+                    settings.hue_ref,
+                    hue_ref
+                );
+                settings.hue_ref = hue_ref;
+            }
+            subclass::Property("hue-var", ..) => {
+                let mut settings = self.settings.lock().unwrap();
+                let hue_var = value.get_some().expect("type checked upstream");
+                gst_info!(
+                    CAT,
+                    obj: obj,
+                    "Changing hue-var from {} to {}",
+                    settings.hue_var,
+                    hue_var
+                );
+                settings.hue_var = hue_var;
+            }
+            subclass::Property("saturation-ref", ..) => {
+                let mut settings = self.settings.lock().unwrap();
+                let saturation_ref = value.get_some().expect("type checked upstream");
+                gst_info!(
+                    CAT,
+                    obj: obj,
+                    "Changing saturation-ref from {} to {}",
+                    settings.saturation_ref,
+                    saturation_ref
+                );
+                settings.saturation_ref = saturation_ref;
+            }
+            subclass::Property("saturation-var", ..) => {
+                let mut settings = self.settings.lock().unwrap();
+                let saturation_var = value.get_some().expect("type checked upstream");
+                gst_info!(
+                    CAT,
+                    obj: obj,
+                    "Changing saturation-var from {} to {}",
+                    settings.saturation_var,
+                    saturation_var
+                );
+                settings.saturation_var = saturation_var;
+            }
+            subclass::Property("value-ref", ..) => {
+                let mut settings = self.settings.lock().unwrap();
+                let value_ref = value.get_some().expect("type checked upstream");
+                gst_info!(
+                    CAT,
+                    obj: obj,
+                    "Changing value-ref from {} to {}",
+                    settings.value_ref,
+                    value_ref
+                );
+                settings.value_ref = value_ref;
+            }
+            subclass::Property("value-var", ..) => {
+                let mut settings = self.settings.lock().unwrap();
+                let value_var = value.get_some().expect("type checked upstream");
+                gst_info!(
+                    CAT,
+                    obj: obj,
+                    "Changing value-var from {} to {}",
+                    settings.value_var,
+                    value_var
+                );
+                settings.value_var = value_var;
+            }
+            _ => unimplemented!(),
+        }
+    }
+
+    // Called whenever a value of a property is read. It can be called
+    // at any time from any thread.
+    fn get_property(&self, _obj: &Self::Type, id: usize) -> glib::Value {
+        let prop = &PROPERTIES[id];
+
+        match *prop {
+            subclass::Property("hue-ref", ..) => {
+                let settings = self.settings.lock().unwrap();
+                settings.hue_ref.to_value()
+            }
+            subclass::Property("hue-var", ..) => {
+                let settings = self.settings.lock().unwrap();
+                settings.hue_var.to_value()
+            }
+            subclass::Property("saturation-ref", ..) => {
+                let settings = self.settings.lock().unwrap();
+                settings.saturation_ref.to_value()
+            }
+            subclass::Property("saturation-var", ..) => {
+                let settings = self.settings.lock().unwrap();
+                settings.saturation_var.to_value()
+            }
+            subclass::Property("value-ref", ..) => {
+                let settings = self.settings.lock().unwrap();
+                settings.value_ref.to_value()
+            }
+            subclass::Property("value-var", ..) => {
+                let settings = self.settings.lock().unwrap();
+                settings.value_var.to_value()
+            }
+            _ => unimplemented!(),
+        }
+    }
+}
+
+impl ElementImpl for HsvDetector {}
+
+impl BaseTransformImpl for HsvDetector {
+    fn transform_caps(
+        &self,
+        element: &Self::Type,
+        direction: gst::PadDirection,
+        caps: &gst::Caps,
+        filter: Option<&gst::Caps>,
+    ) -> Option<gst::Caps> {
+        let other_caps = if direction == gst::PadDirection::Src {
+            let mut caps = caps.clone();
+
+            for s in caps.make_mut().iter_mut() {
+                s.set("format", &gst_video::VideoFormat::Rgbx.to_str());
+            }
+
+            caps
+        } else {
+            let mut caps = caps.clone();
+
+            for s in caps.make_mut().iter_mut() {
+                s.set("format", &gst_video::VideoFormat::Rgba.to_str());
+            }
+
+            caps
+        };
+
+        gst_debug!(
+            CAT,
+            obj: element,
+            "Transformed caps from {} to {} in direction {:?}",
+            caps,
+            other_caps,
+            direction
+        );
+
+        // In the end we need to filter the caps through an optional filter caps to get rid of any
+        // unwanted caps.
+        if let Some(filter) = filter {
+            Some(filter.intersect_with_mode(&other_caps, gst::CapsIntersectMode::First))
+        } else {
+            Some(other_caps)
+        }
+    }
+
+    fn get_unit_size(&self, _element: &Self::Type, caps: &gst::Caps) -> Option<usize> {
+        gst_video::VideoInfo::from_caps(caps)
+            .map(|info| info.size())
+            .ok()
+    }
+
+    fn set_caps(
+        &self,
+        element: &Self::Type,
+        incaps: &gst::Caps,
+        outcaps: &gst::Caps,
+    ) -> Result<(), gst::LoggableError> {
+        let in_info = match gst_video::VideoInfo::from_caps(incaps) {
+            Err(_) => return Err(gst::loggable_error!(CAT, "Failed to parse input caps")),
+            Ok(info) => info,
+        };
+        let out_info = match gst_video::VideoInfo::from_caps(outcaps) {
+            Err(_) => return Err(gst::loggable_error!(CAT, "Failed to parse output caps")),
+            Ok(info) => info,
+        };
+
+        gst_debug!(
+            CAT,
+            obj: element,
+            "Configured for caps {} to {}",
+            incaps,
+            outcaps
+        );
+
+        *self.state.borrow_mut() = Some(State { in_info, out_info });
+
+        Ok(())
+    }
+
+    fn stop(&self, element: &Self::Type) -> Result<(), gst::ErrorMessage> {
+        // Drop state
+        *self.state.borrow_mut() = None;
+
+        gst_info!(CAT, obj: element, "Stopped");
+
+        Ok(())
+    }
+
+    fn transform(
+        &self,
+        element: &Self::Type,
+        inbuf: &gst::Buffer,
+        outbuf: &mut gst::BufferRef,
+    ) -> Result<gst::FlowSuccess, gst::FlowError> {
+        let settings = *self.settings.lock().unwrap();
+
+        let mut state_guard = self.state.borrow_mut();
+        let state = state_guard.as_mut().ok_or(gst::FlowError::NotNegotiated)?;
+
+        let in_frame =
+            gst_video::VideoFrameRef::from_buffer_ref_readable(inbuf.as_ref(), &state.in_info)
+                .map_err(|_| {
+                    gst::element_error!(
+                        element,
+                        gst::CoreError::Failed,
+                        ["Failed to map input buffer readable"]
+                    );
+                    gst::FlowError::Error
+                })?;
+
+        // And now map the output buffer writable, so we can fill it.
+        let mut out_frame =
+            gst_video::VideoFrameRef::from_buffer_ref_writable(outbuf, &state.out_info).map_err(
+                |_| {
+                    gst::element_error!(
+                        element,
+                        gst::CoreError::Failed,
+                        ["Failed to map output buffer writable"]
+                    );
+                    gst::FlowError::Error
+                },
+            )?;
+
+        // Keep the various metadata we need for working with the video frames in
+        // local variables. This saves some typing below.
+        let width = in_frame.width() as usize;
+        let in_stride = in_frame.plane_stride()[0] as usize;
+        let in_data = in_frame.plane_data(0).unwrap();
+        let out_stride = out_frame.plane_stride()[0] as usize;
+        let out_data = out_frame.plane_data_mut(0).unwrap();
+
+        assert_eq!(in_data.len() % 4, 0);
+        assert_eq!(out_data.len() / out_stride, in_data.len() / in_stride);
+
+        let in_line_bytes = width * 4;
+        let out_line_bytes = width * 4;
+
+        assert!(in_line_bytes <= in_stride);
+        assert!(out_line_bytes <= out_stride);
+
+        for (in_line, out_line) in in_data
+            .chunks_exact(in_stride)
+            .zip(out_data.chunks_exact_mut(out_stride))
+        {
+            for (in_p, out_p) in in_line[..in_line_bytes]
+                .chunks_exact(4)
+                .zip(out_line[..out_line_bytes].chunks_exact_mut(4))
+            {
+                assert_eq!(out_p.len(), 4);
+                let hsv =
+                    hsvutils::from_rgb(in_p[..3].try_into().expect("slice with incorrect length"));
+
+                // We handle hue being circular here
+                let ref_hue_offset = 180.0 - settings.hue_ref;
+                let mut shifted_hue = hsv[0] + ref_hue_offset;
+
+                if shifted_hue < 0.0 {
+                    shifted_hue += 360.0;
+                }
+
+                shifted_hue %= 360.0;
+
+                out_p[..3].copy_from_slice(&in_p[..3]);
+
+                out_p[3] = if (shifted_hue - 180.0).abs() <= settings.hue_var
+                    && (hsv[1] - settings.saturation_ref).abs() <= settings.saturation_var
+                    && (hsv[2] - settings.value_ref).abs() <= settings.value_var
+                {
+                    255
+                } else {
+                    0
+                };
+            }
+        }
+
+        Ok(gst::FlowSuccess::Ok)
+    }
+}

video/hsv/src/hsvdetector/mod.rs

@@ -0,0 +1,29 @@
+// Copyright (C) 2020 Julien Bardagi <julien.bardagi@gmail.com>
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use glib::prelude::*;
+
+mod imp;
+
+glib::wrapper! {
+    pub struct HsvDetector(ObjectSubclass<imp::HsvDetector>) @extends gst_base::BaseTransform, gst::Element, gst::Object;
+}
+
+// GStreamer elements need to be thread-safe. For the private implementation this is automatically
+// enforced but for the public wrapper type we need to specify this manually.
+unsafe impl Send for HsvDetector {}
+unsafe impl Sync for HsvDetector {}
+
+pub fn register(plugin: &gst::Plugin) -> Result<(), glib::BoolError> {
+    gst::Element::register(
+        Some(plugin),
+        "hsvdetector",
+        gst::Rank::None,
+        HsvDetector::static_type(),
+    )
+}

video/hsv/src/hsvfilter/imp.rs

@@ -0,0 +1,410 @@
+// Copyright (C) 2020 Julien Bardagi <julien.bardagi@gmail.com>
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use glib::subclass;
+use glib::subclass::prelude::*;
+use gst::prelude::*;
+use gst::subclass::prelude::*;
+use gst::{gst_debug, gst_info};
+use gst_base::subclass::prelude::*;
+
+use atomic_refcell::AtomicRefCell;
+use std::i32;
+use std::sync::Mutex;
+
+use once_cell::sync::Lazy;
+use std::convert::TryInto;
+
+use super::super::hsvutils;
+
+// Default values of properties
+const DEFAULT_HUE_SHIFT: f32 = 0.0;
+const DEFAULT_SATURATION_MUL: f32 = 1.0;
+const DEFAULT_SATURATION_OFF: f32 = 0.0;
+const DEFAULT_VALUE_MUL: f32 = 1.0;
+const DEFAULT_VALUE_OFF: f32 = 0.0;
+
+// Property value storage
+#[derive(Debug, Clone, Copy)]
+struct Settings {
+    hue_shift: f32,
+    saturation_mul: f32,
+    saturation_off: f32,
+    value_mul: f32,
+    value_off: f32,
+}
+
+impl Default for Settings {
+    fn default() -> Self {
+        Settings {
+            hue_shift: DEFAULT_HUE_SHIFT,
+            saturation_mul: DEFAULT_SATURATION_MUL,
+            saturation_off: DEFAULT_SATURATION_OFF,
+            value_mul: DEFAULT_VALUE_MUL,
+            value_off: DEFAULT_VALUE_OFF,
+        }
+    }
+}
+
+// Metadata for the properties
+static PROPERTIES: [subclass::Property; 5] = [
+    subclass::Property("hue-shift", |name| {
+        glib::ParamSpec::float(
+            name,
+            "Hue shift",
+            "Hue shifting in degrees",
+            f32::MIN,
+            f32::MAX,
+            DEFAULT_HUE_SHIFT,
+            glib::ParamFlags::READWRITE,
+        )
+    }),
+    subclass::Property("saturation-mul", |name| {
+        glib::ParamSpec::float(
+            name,
+            "Saturation multiplier",
+            "Saturation multiplier to apply to the saturation value (before offset)",
+            f32::MIN,
+            f32::MAX,
+            DEFAULT_SATURATION_MUL,
+            glib::ParamFlags::READWRITE,
+        )
+    }),
+    subclass::Property("saturation-off", |name| {
+        glib::ParamSpec::float(
+            name,
+            "Saturation offset",
+            "Saturation offset to add to the saturation value (after multiplier)",
+            f32::MIN,
+            f32::MAX,
+            DEFAULT_SATURATION_OFF,
+            glib::ParamFlags::READWRITE,
+        )
+    }),
+    subclass::Property("value-mul", |name| {
+        glib::ParamSpec::float(
+            name,
+            "Value multiplier",
+            "Value multiplier to apply to the value (before offset)",
+            f32::MIN,
+            f32::MAX,
+            DEFAULT_VALUE_MUL,
+            glib::ParamFlags::READWRITE,
+        )
+    }),
+    subclass::Property("value-off", |name| {
+        glib::ParamSpec::float(
+            name,
+            "Value offset",
+            "Value offset to add to the value (after multiplier)",
+            f32::MIN,
+            f32::MAX,
+            DEFAULT_VALUE_OFF,
+            glib::ParamFlags::READWRITE,
+        )
+    }),
+];
+
+// Stream-specific state, i.e. video format configuration
+struct State {
+    info: gst_video::VideoInfo,
+}
+
+// Struct containing all the element data
+pub struct HsvFilter {
+    settings: Mutex<Settings>,
+    state: AtomicRefCell<Option<State>>,
+}
+
+static CAT: Lazy<gst::DebugCategory> = Lazy::new(|| {
+    gst::DebugCategory::new(
+        "hsvfilter",
+        gst::DebugColorFlags::empty(),
+        Some("Rust HSV transformation filter"),
+    )
+});
+
+impl ObjectSubclass for HsvFilter {
+    const NAME: &'static str = "HsvFilter";
+    type Type = super::HsvFilter;
+    type ParentType = gst_base::BaseTransform;
+    type Instance = gst::subclass::ElementInstanceStruct<Self>;
+    type Class = subclass::simple::ClassStruct<Self>;
+
+    // Boilerplate macro
+    glib::object_subclass!();
+
+    // Creates a new instance.
+    fn new() -> Self {
+        Self {
+            settings: Mutex::new(Default::default()),
+            state: AtomicRefCell::new(None),
+        }
+    }
+
+    fn class_init(klass: &mut Self::Class) {
+        klass.set_metadata(
+            "HSV filter",
+            "Filter/Effect/Converter/Video",
+            "Works within the HSV colorspace to apply tranformations to incoming frames",
+            "Julien Bardagi <julien.bardagi@gmail.com>",
+        );
+
+        // src pad capabilities
+        let caps = gst::Caps::new_simple(
+            "video/x-raw",
+            &[
+                (
+                    "format",
+                    &gst::List::new(&[&gst_video::VideoFormat::Rgbx.to_str()]),
+                ),
+                ("width", &gst::IntRange::<i32>::new(0, i32::MAX)),
+                ("height", &gst::IntRange::<i32>::new(0, i32::MAX)),
+                (
+                    "framerate",
+                    &gst::FractionRange::new(
+                        gst::Fraction::new(0, 1),
+                        gst::Fraction::new(i32::MAX, 1),
+                    ),
+                ),
+            ],
+        );
+
+        let src_pad_template = gst::PadTemplate::new(
+            "src",
+            gst::PadDirection::Src,
+            gst::PadPresence::Always,
+            &caps,
+        )
+        .unwrap();
+        klass.add_pad_template(src_pad_template);
+
+        let sink_pad_template = gst::PadTemplate::new(
+            "sink",
+            gst::PadDirection::Sink,
+            gst::PadPresence::Always,
+            &caps,
+        )
+        .unwrap();
+        klass.add_pad_template(sink_pad_template);
+
+        // Install all our properties
+        klass.install_properties(&PROPERTIES);
+
+        klass.configure(
+            gst_base::subclass::BaseTransformMode::AlwaysInPlace,
+            false,
+            false,
+        );
+    }
+}
+
+impl ObjectImpl for HsvFilter {
+    fn set_property(&self, obj: &Self::Type, id: usize, value: &glib::Value) {
+        let prop = &PROPERTIES[id];
+
+        match *prop {
+            subclass::Property("hue-shift", ..) => {
+                let mut settings = self.settings.lock().unwrap();
+                let hue_shift = value.get_some().expect("type checked upstream");
+                gst_info!(
+                    CAT,
+                    obj: obj,
+                    "Changing hue-shift from {} to {}",
+                    settings.hue_shift,
+                    hue_shift
+                );
+                settings.hue_shift = hue_shift;
+            }
+            subclass::Property("saturation-mul", ..) => {
+                let mut settings = self.settings.lock().unwrap();
+                let saturation_mul = value.get_some().expect("type checked upstream");
+                gst_info!(
+                    CAT,
+                    obj: obj,
+                    "Changing saturation-mul from {} to {}",
+                    settings.saturation_mul,
+                    saturation_mul
+                );
+                settings.saturation_mul = saturation_mul;
+            }
+            subclass::Property("saturation-off", ..) => {
+                let mut settings = self.settings.lock().unwrap();
+                let saturation_off = value.get_some().expect("type checked upstream");
+                gst_info!(
+                    CAT,
+                    obj: obj,
+                    "Changing saturation-off from {} to {}",
+                    settings.saturation_off,
+                    saturation_off
+                );
+                settings.saturation_off = saturation_off;
+            }
+            subclass::Property("value-mul", ..) => {
+                let mut settings = self.settings.lock().unwrap();
+                let value_mul = value.get_some().expect("type checked upstream");
+                gst_info!(
+                    CAT,
+                    obj: obj,
+                    "Changing value-mul from {} to {}",
+                    settings.value_mul,
+                    value_mul
+                );
+                settings.value_mul = value_mul;
+            }
+            subclass::Property("value-off", ..) => {
+                let mut settings = self.settings.lock().unwrap();
+                let value_off = value.get_some().expect("type checked upstream");
+                gst_info!(
+                    CAT,
+                    obj: obj,
+                    "Changing value-off from {} to {}",
+                    settings.value_off,
+                    value_off
+                );
+                settings.value_off = value_off;
+            }
+            _ => unimplemented!(),
+        }
+    }
+
+    // Called whenever a value of a property is read. It can be called
+    // at any time from any thread.
+    fn get_property(&self, _obj: &Self::Type, id: usize) -> glib::Value {
+        let prop = &PROPERTIES[id];
+
+        match *prop {
+            subclass::Property("hue-shift", ..) => {
+                let settings = self.settings.lock().unwrap();
+                settings.hue_shift.to_value()
+            }
+            subclass::Property("saturation-mul", ..) => {
+                let settings = self.settings.lock().unwrap();
+                settings.saturation_mul.to_value()
+            }
+            subclass::Property("saturation-off", ..) => {
+                let settings = self.settings.lock().unwrap();
+                settings.saturation_off.to_value()
+            }
+            subclass::Property("value-mul", ..) => {
+                let settings = self.settings.lock().unwrap();
+                settings.value_mul.to_value()
+            }
+            subclass::Property("value-off", ..) => {
+                let settings = self.settings.lock().unwrap();
+                settings.value_off.to_value()
+            }
+            _ => unimplemented!(),
+        }
+    }
+}
+
+impl ElementImpl for HsvFilter {}
+
+impl BaseTransformImpl for HsvFilter {
+    fn get_unit_size(&self, _element: &Self::Type, caps: &gst::Caps) -> Option<usize> {
+        gst_video::VideoInfo::from_caps(caps)
+            .map(|info| info.size())
+            .ok()
+    }
+
+    fn set_caps(
+        &self,
+        element: &Self::Type,
+        incaps: &gst::Caps,
+        outcaps: &gst::Caps,
+    ) -> Result<(), gst::LoggableError> {
+        let _in_info = match gst_video::VideoInfo::from_caps(incaps) {
+            Err(_) => return Err(gst::loggable_error!(CAT, "Failed to parse input caps")),
+            Ok(info) => info,
+        };
+        let out_info = match gst_video::VideoInfo::from_caps(outcaps) {
+            Err(_) => return Err(gst::loggable_error!(CAT, "Failed to parse output caps")),
+            Ok(info) => info,
+        };
+
+        gst_debug!(
+            CAT,
+            obj: element,
+            "Configured for caps {} to {}",
+            incaps,
+            outcaps
+        );
+
+        *self.state.borrow_mut() = Some(State { info: out_info });
+
+        Ok(())
+    }
+
+    fn stop(&self, element: &Self::Type) -> Result<(), gst::ErrorMessage> {
+        // Drop state
+        *self.state.borrow_mut() = None;
+
+        gst_info!(CAT, obj: element, "Stopped");
+
+        Ok(())
+    }
+
+    fn transform_ip(
+        &self,
+        element: &Self::Type,
+        buf: &mut gst::BufferRef,
+    ) -> Result<gst::FlowSuccess, gst::FlowError> {
+        let settings = *self.settings.lock().unwrap();
+
+        let mut state_guard = self.state.borrow_mut();
+        let state = state_guard.as_mut().ok_or(gst::FlowError::NotNegotiated)?;
+
+        let mut frame = gst_video::VideoFrameRef::from_buffer_ref_writable(buf, &state.info)
+            .map_err(|_| {
+                gst::element_error!(
+                    element,
+                    gst::CoreError::Failed,
+                    ["Failed to map output buffer writable"]
+                );
+                gst::FlowError::Error
+            })?;
+
+        let width = frame.width() as usize;
+        let stride = frame.plane_stride()[0] as usize;
+        let format = frame.format();
+        let data = frame.plane_data_mut(0).unwrap();
+
+        assert_eq!(format, gst_video::VideoFormat::Rgbx);
+        assert_eq!(data.len() % 4, 0);
+
+        let line_bytes = width * 4;
+
+        for line in data.chunks_exact_mut(stride) {
+            for p in line[..line_bytes].chunks_exact_mut(4) {
+                assert_eq!(p.len(), 4);
+
+                let mut hsv =
+                    hsvutils::from_rgb(p[..3].try_into().expect("slice with incorrect length"));
+                hsv[0] = (hsv[0] + settings.hue_shift) % 360.0;
+                if hsv[0] < 0.0 {
+                    hsv[0] += 360.0;
+                }
+                hsv[1] = hsvutils::Clamp::clamp(
+                    settings.saturation_mul * hsv[1] + settings.saturation_off,
+                    0.0,
+                    1.0,
+                );
+                hsv[2] = hsvutils::Clamp::clamp(
+                    settings.value_mul * hsv[2] + settings.value_off,
+                    0.0,
+                    1.0,
+                );
+
+                p[..3].copy_from_slice(&hsvutils::to_rgb(&hsv));
+            }
+        }
+
+        Ok(gst::FlowSuccess::Ok)
+    }
+}

video/hsv/src/hsvfilter/mod.rs

@@ -0,0 +1,29 @@
+// Copyright (C) 2020 Julien Bardagi <julien.bardagi@gmail.com>
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use glib::prelude::*;
+
+mod imp;
+
+glib::wrapper! {
+    pub struct HsvFilter(ObjectSubclass<imp::HsvFilter>) @extends gst_base::BaseTransform, gst::Element, gst::Object;
+}
+
+// GStreamer elements need to be thread-safe. For the private implementation this is automatically
+// enforced but for the public wrapper type we need to specify this manually.
+unsafe impl Send for HsvFilter {}
+unsafe impl Sync for HsvFilter {}
+
+pub fn register(plugin: &gst::Plugin) -> Result<(), glib::BoolError> {
+    gst::Element::register(
+        Some(plugin),
+        "hsvfilter",
+        gst::Rank::None,
+        HsvFilter::static_type(),
+    )
+}

video/hsv/src/hsvutils.rs

@@ -0,0 +1,173 @@
+// Copyright (C) 2020 Julien Bardagi <julien.bardagi@gmail.com>
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// Reference used for implementation: https://en.wikipedia.org/wiki/HSL_and_HSV
+
+#![allow(unstable_name_collisions)]
+
+// Since the standard 'clamp' feature is still considered unstable, we provide
+// a subsititute implementaion here so we can still build with the stable toolchain.
+// Source: https://github.com/rust-lang/rust/issues/44095#issuecomment-624879262
+pub trait Clamp: Sized {
+    fn clamp<L, U>(self, lower: L, upper: U) -> Self
+    where
+        L: Into<Option<Self>>,
+        U: Into<Option<Self>>;
+}
+
+impl Clamp for f32 {
+    fn clamp<L, U>(self, lower: L, upper: U) -> Self
+    where
+        L: Into<Option<Self>>,
+        U: Into<Option<Self>>,
+    {
+        let below = match lower.into() {
+            None => self,
+            Some(lower) => self.max(lower),
+        };
+        match upper.into() {
+            None => below,
+            Some(upper) => below.min(upper),
+        }
+    }
+}
+
+const EPSILON: f32 = 0.00001;
+
+// Converts a RGB pixel to HSV
+#[inline]
+pub fn from_rgb(in_p: &[u8; 3]) -> [f32; 3] {
+    let r = in_p[0] as f32 / 255.0;
+    let g = in_p[1] as f32 / 255.0;
+    let b = in_p[2] as f32 / 255.0;
+
+    let value: f32 = *in_p
+        .iter()
+        .max()
+        .expect("Cannot find max value from rgb input") as f32
+        / 255.0;
+    let chroma: f32 = value
+        - (*in_p
+            .iter()
+            .min()
+            .expect("Cannot find min value from rgb input") as f32
+            / 255.0);
+
+    let mut hue: f32 = if chroma == 0.0 {
+        0.0
+    } else if (value - r).abs() < EPSILON {
+        60.0 * ((g - b) / chroma)
+    } else if (value - g).abs() < EPSILON {
+        60.0 * (2.0 + ((b - r) / chroma))
+    } else if (value - b).abs() < EPSILON {
+        60.0 * (4.0 + ((r - g) / chroma))
+    } else {
+        0.0
+    };
+
+    if hue < 0.0 {
+        hue += 360.0;
+    }
+
+    let saturation: f32 = if value == 0.0 { 0.0 } else { chroma / value };
+
+    [
+        hue % 360.0,
+        saturation.clamp(0.0, 1.0),
+        value.clamp(0.0, 1.0),
+    ]
+}
+
+// Converts a HSV pixel to RGB
+#[inline]
+pub fn to_rgb(in_p: &[f32; 3]) -> [u8; 3] {
+    let c: f32 = in_p[2] * in_p[1];
+    let hue_prime: f32 = in_p[0] / 60.0;
+
+    let x: f32 = c * (1.0 - ((hue_prime % 2.0) - 1.0).abs());
+
+    let rgb_prime = if hue_prime < 0.0 {
+        [0.0, 0.0, 0.0]
+    } else if hue_prime <= 1.0 {
+        [c, x, 0.0]
+    } else if hue_prime <= 2.0 {
+        [x, c, 0.0]
+    } else if hue_prime <= 3.0 {
+        [0.0, c, x]
+    } else if hue_prime <= 4.0 {
+        [0.0, x, c]
+    } else if hue_prime <= 5.0 {
+        [x, 0.0, c]
+    } else if hue_prime <= 6.0 {
+        [c, 0.0, x]
+    } else {
+        [0.0, 0.0, 0.0]
+    };
+
+    let m = in_p[2] - c;
+
+    [
+        ((rgb_prime[0] + m) * 255.0).clamp(0.0, 255.0) as u8,
+        ((rgb_prime[1] + m) * 255.0).clamp(0.0, 255.0) as u8,
+        ((rgb_prime[2] + m) * 255.0).clamp(0.0, 255.0) as u8,
+    ]
+}
+
+#[cfg(test)]
+mod tests {
+
+    fn is_equivalent(hsv: &[f32; 3], expected: &[f32; 3], eps: f32) -> bool {
+        // We handle hue being circular here
+        let ref_hue_offset = 180.0 - expected[0];
+        let mut shifted_hue = hsv[0] + ref_hue_offset;
+
+        if shifted_hue < 0.0 {
+            shifted_hue += 360.0;
+        }
+
+        shifted_hue %= 360.0;
+
+        (shifted_hue - 180.0).abs() < eps
+            && (hsv[1] - expected[1]).abs() < eps
+            && (hsv[2] - expected[2]).abs() < eps
+    }
+
+    const RGB_WHITE: [u8; 3] = [255, 255, 255];
+    const RGB_BLACK: [u8; 3] = [0, 0, 0];
+    const RGB_RED: [u8; 3] = [255, 0, 0];
+    const RGB_GREEN: [u8; 3] = [0, 255, 0];
+    const RGB_BLUE: [u8; 3] = [0, 0, 255];
+
+    const HSV_WHITE: [f32; 3] = [0.0, 0.0, 1.0];
+    const HSV_BLACK: [f32; 3] = [0.0, 0.0, 0.0];
+    const HSV_RED: [f32; 3] = [0.0, 1.0, 1.0];
+    const HSV_GREEN: [f32; 3] = [120.0, 1.0, 1.0];
+    const HSV_BLUE: [f32; 3] = [240.0, 1.0, 1.0];
+
+    #[test]
+    fn test_from_rgb() {
+        use super::*;
+
+        assert!(is_equivalent(&from_rgb(&RGB_WHITE), &HSV_WHITE, EPSILON));
+        assert!(is_equivalent(&from_rgb(&RGB_BLACK), &HSV_BLACK, EPSILON));
+        assert!(is_equivalent(&from_rgb(&RGB_RED), &HSV_RED, EPSILON));
+        assert!(is_equivalent(&from_rgb(&RGB_GREEN), &HSV_GREEN, EPSILON));
+        assert!(is_equivalent(&from_rgb(&RGB_BLUE), &HSV_BLUE, EPSILON));
+    }
+
+    #[test]
+    fn test_to_rgb() {
+        use super::*;
+
+        assert!(to_rgb(&HSV_WHITE) == RGB_WHITE);
+        assert!(to_rgb(&HSV_BLACK) == RGB_BLACK);
+        assert!(to_rgb(&HSV_RED) == RGB_RED);
+        assert!(to_rgb(&HSV_GREEN) == RGB_GREEN);
+        assert!(to_rgb(&HSV_BLUE) == RGB_BLUE);
+    }
+}

video/hsv/src/lib.rs

@@ -0,0 +1,29 @@
+// Copyright (C) 2020 Julien Bardagi <julien.bardagi@gmail.com>
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+mod hsvdetector;
+mod hsvfilter;
+mod hsvutils;
+
+fn plugin_init(plugin: &gst::Plugin) -> Result<(), glib::BoolError> {
+    hsvfilter::register(plugin)?;
+    hsvdetector::register(plugin)?;
+    Ok(())
+}
+
+gst::plugin_define!(
+    hsv,
+    env!("CARGO_PKG_DESCRIPTION"),
+    plugin_init,
+    concat!(env!("CARGO_PKG_VERSION"), "-", env!("COMMIT_ID")),
+    "MIT/X11",
+    env!("CARGO_PKG_NAME"),
+    env!("CARGO_PKG_NAME"),
+    env!("CARGO_PKG_REPOSITORY"),
+    env!("BUILD_REL_DATE")
+);