diff --git a/Cargo.toml b/Cargo.toml
index 0cd39d8..9814411 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -6,11 +6,12 @@ members = [
     "poc002",
     "poc003",
     "poc004",
+    "poc005",
 ]
 resolver = "3"
 
 [workspace.package]
-version = "0.4.0"
+version = "0.5.0"
 edition = "2024"
 license = "MIT"
 repository = "https://git.sasedev.com/Sasedev/poc-qt"
@@ -21,9 +22,18 @@ cxx = { version = "^1", features = ["c++14", "c++17", "c++20"] }
 cxx-qt = { version = "^0.8", features = [] }
 cxx-qt-build = { version = "^0.8", features = ["link_qt_object_files"] }
 cxx-qt-lib = { version = "^0.8", features = ["full", "link_qt_object_files"] }
+glib = { version = "^0.22", features = [] }
+gstreamer = { version = "^0.25", features = ["serde"] }
+gstreamer-app = { version = "^0.25", features = [] }
+gstreamer-video = { version = "^0.25", features = ["serde"] }
 jsonschema = { version = "^0.40", features = [] }
 serde = { version = "^1.0", features = ["derive"] }
 serde_json = { version = "^1.0", features = [] }
+tokio = { version = "^1.50", features = ["full"] }
+tokio-tungstenite = { version = "^0.29", features = ["rustls", "tokio-rustls", "url"] }
+tracing = { version = "^0.1", features = ["async-await", "log"] }
+tracing-subscriber = { version = "^0.3", features = ["ansi", "env-filter", "chrono", "serde", "json"] }
+webrtc = { version = "^0.17", features = [] }
 
 [profile.dev]
 incremental = true # Compile your binary in smaller steps.
diff --git a/poc005/Cargo.toml b/poc005/Cargo.toml
new file mode 100644
index 0000000..e00f1e1
--- /dev/null
+++ b/poc005/Cargo.toml
@@ -0,0 +1,24 @@
+# file: poc-qt/poc005/Cargo.toml
+
+[package]
+name = "poc-qt005"
+version = "0.5.0"
+edition.workspace = true
+license.workspace = true
+authors.workspace = true
+
+[build-dependencies]
+cxx-qt-build = { workspace = true, features = ["link_qt_object_files"] }
+jsonschema = { workspace = true, features = [] }
+serde = { workspace = true, features = ["derive"] }
+serde_json = { workspace = true, features = [] }
+
+[dependencies]
+cxx = { workspace = true, features = [] }
+cxx-qt = { workspace = true, features = [] }
+cxx-qt-lib = { workspace = true, features = ["full", "link_qt_object_files"] }
+glib = { workspace = true, features = [] }
+gstreamer = { workspace = true, features = ["serde"] }
+gstreamer-app = { workspace = true, features = [] }
+gstreamer-video = { workspace = true, features = ["serde"] }
+
diff --git a/poc005/build.rs b/poc005/build.rs
new file mode 100644
index 0000000..daaa320
--- /dev/null
+++ b/poc005/build.rs
@@ -0,0 +1,298 @@
+// file: poc-qt/poc005/build.rs
+
+use std::collections::BTreeMap;
+use std::fs;
+use std::path::{Path, PathBuf};
+
+use cxx_qt_build::{CxxQtBuilder, QmlModule};
+use serde::Deserialize;
+use serde_json::Value;
+
+const DEFAULT_CONFIG_STR: &str = include_str!("build_config.default.json");
+const CONFIG_SCHEMA_STR: &str = include_str!("../build_config.schema.json");
+
+#[derive(Debug, Deserialize)]
+struct BuildConfig {
+    active_profile: String,
+    profiles: BTreeMap<String, BuildProfile>,
+}
+
+#[derive(Debug, Deserialize)]
+struct BuildProfile {
+    qt: QtConfig,
+    link: LinkConfig,
+}
+
+#[derive(Debug, Deserialize)]
+struct QtConfig {
+    qmake: String,
+    lib_dir: String,
+    qml_dir: String,
+    plugins_dir: String,
+    version_major: u8,
+}
+
+#[derive(Debug, Deserialize)]
+struct LinkConfig {
+    rpaths: Vec<String>,
+}
+
+fn ensure_user_config_exists(config_path: &Path) {
+    if config_path.exists() {
+        return;
+    }
+
+    match fs::write(config_path, DEFAULT_CONFIG_STR) {
+        Ok(()) => {
+            println!(
+                "cargo:warning=build_config.json was missing and has been created from build_config.default.json"
+            );
+        }
+        Err(err) => {
+            panic!(
+                "failed to create {} from embedded defaults: {}",
+                config_path.display(),
+                err
+            );
+        }
+    }
+}
+
+fn validate_embedded_schema() {
+    let schema_json = parse_json_str(CONFIG_SCHEMA_STR, "embedded build_config.schema.json");
+
+    match jsonschema::meta::validate(&schema_json) {
+        Ok(()) => {}
+        Err(err) => {
+            panic!("embedded build_config.schema.json is not a valid JSON Schema: {err}");
+        }
+    }
+}
+
+fn validate_default_config() {
+    validate_config_str_against_schema(DEFAULT_CONFIG_STR, "embedded build_config.default.json");
+}
+
+fn validate_user_config(config_path: &Path) {
+    let raw = match fs::read_to_string(config_path) {
+        Ok(v) => v,
+        Err(err) => {
+            panic!("failed to read {}: {}", config_path.display(), err);
+        }
+    };
+
+    validate_config_str_against_schema(&raw, &format!("{}", config_path.display()));
+}
+
+fn validate_config_str_against_schema(config_raw: &str, config_name: &str) {
+    let schema_json = parse_json_str(CONFIG_SCHEMA_STR, "embedded build_config.schema.json");
+    let config_json = parse_json_str(config_raw, config_name);
+
+    let validator = match jsonschema::validator_for(&schema_json) {
+        Ok(v) => v,
+        Err(err) => {
+            panic!(
+                "failed to build JSON Schema validator for {}: {}",
+                config_name, err
+            );
+        }
+    };
+
+    if validator.is_valid(&config_json) {
+        return;
+    }
+
+    let mut errors = Vec::new();
+    for err in validator.iter_errors(&config_json) {
+        errors.push(format!(
+            "- {} at instance path {}",
+            err,
+            err.instance_path()
+        ));
+    }
+
+    let joined = errors.join("\n");
+    panic!("{} failed schema validation:\n{}", config_name, joined);
+}
+
+fn load_build_config(config_path: &Path) -> BuildConfig {
+    let raw = match fs::read_to_string(config_path) {
+        Ok(v) => v,
+        Err(err) => {
+            panic!("failed to read {}: {}", config_path.display(), err);
+        }
+    };
+
+    match serde_json::from_str::<BuildConfig>(&raw) {
+        Ok(v) => v,
+        Err(err) => {
+            panic!(
+                "failed to deserialize {} into BuildConfig: {}",
+                config_path.display(),
+                err
+            );
+        }
+    }
+}
+
+fn resolve_profile_name(build_config: &BuildConfig) -> String {
+    let env_profile = std::env::var("BUILD_CONFIG_PROFILE");
+    match env_profile {
+        Ok(v) => {
+            if v.trim().is_empty() {
+                build_config.active_profile.clone()
+            } else {
+                v
+            }
+        }
+        Err(_) => build_config.active_profile.clone(),
+    }
+}
+
+fn resolve_profile<'a>(build_config: &'a BuildConfig, profile_name: &str) -> &'a BuildProfile {
+    match build_config.profiles.get(profile_name) {
+        Some(v) => v,
+        None => {
+            let mut available = Vec::new();
+            for key in build_config.profiles.keys() {
+                available.push(key.clone());
+            }
+            panic!(
+                "active profile '{}' not found in build_config.json. available profiles: {}",
+                profile_name,
+                available.join(", ")
+            );
+        }
+    }
+}
+
+fn validate_profile_paths(profile: &BuildProfile, profile_name: &str) {
+    ensure_existing_file(&profile.qt.qmake, profile_name, "qt.qmake");
+    ensure_existing_dir(&profile.qt.lib_dir, profile_name, "qt.lib_dir");
+    ensure_existing_dir(&profile.qt.qml_dir, profile_name, "qt.qml_dir");
+    ensure_existing_dir(&profile.qt.plugins_dir, profile_name, "qt.plugins_dir");
+
+    let mut index = 0usize;
+    while index < profile.link.rpaths.len() {
+        ensure_existing_dir(
+            &profile.link.rpaths[index],
+            profile_name,
+            &format!("link.rpaths[{index}]"),
+        );
+        index += 1;
+    }
+}
+
+fn ensure_existing_file(path_str: &str, profile_name: &str, field_name: &str) {
+    let path = Path::new(path_str);
+    if !path.exists() {
+        panic!(
+            "profile '{}' has invalid {}: path does not exist: {}",
+            profile_name,
+            field_name,
+            path.display()
+        );
+    }
+    if !path.is_file() {
+        panic!(
+            "profile '{}' has invalid {}: path is not a file: {}",
+            profile_name,
+            field_name,
+            path.display()
+        );
+    }
+}
+
+fn ensure_existing_dir(path_str: &str, profile_name: &str, field_name: &str) {
+    let path = Path::new(path_str);
+    if !path.exists() {
+        panic!(
+            "profile '{}' has invalid {}: path does not exist: {}",
+            profile_name,
+            field_name,
+            path.display()
+        );
+    }
+    if !path.is_dir() {
+        panic!(
+            "profile '{}' has invalid {}: path is not a directory: {}",
+            profile_name,
+            field_name,
+            path.display()
+        );
+    }
+}
+
+fn apply_build_environment(profile: &BuildProfile) {
+    unsafe {
+        std::env::set_var("QMAKE", &profile.qt.qmake);
+        std::env::set_var("QT_VERSION_MAJOR", profile.qt.version_major.to_string());
+    }
+
+    println!("cargo:rerun-if-env-changed=BUILD_CONFIG_PROFILE");
+    println!("cargo:rerun-if-env-changed=QMAKE");
+    println!("cargo:rerun-if-env-changed=QT_VERSION_MAJOR");
+}
+
+fn apply_linker_settings(profile: &BuildProfile) {
+    let mut index = 0usize;
+    while index < profile.link.rpaths.len() {
+        println!(
+            "cargo:rustc-link-arg=-Wl,-rpath,{}",
+            profile.link.rpaths[index]
+        );
+        index += 1;
+    }
+}
+
+fn emit_runtime_hints(profile: &BuildProfile, profile_name: &str) {
+    println!(
+        "cargo:warning=using build profile '{}' with qmake '{}'",
+        profile_name, profile.qt.qmake
+    );
+    println!(
+        "cargo:warning=qt lib_dir='{}', qml_dir='{}', plugins_dir='{}'",
+        profile.qt.lib_dir, profile.qt.qml_dir, profile.qt.plugins_dir
+    );
+}
+
+fn parse_json_str(raw: &str, label: &str) -> Value {
+    match serde_json::from_str::<Value>(raw) {
+        Ok(v) => v,
+        Err(err) => {
+            panic!("failed to parse {} as JSON: {}", label, err);
+        }
+    }
+}
+
+fn main() {
+    println!("cargo:rerun-if-changed=build.rs");
+    println!("cargo:rerun-if-changed=build_config.default.json");
+    println!("cargo:rerun-if-changed=build_config.schema.json");
+    println!("cargo:rerun-if-changed=src/bridge.rs");
+    println!("cargo:rerun-if-changed=qml/main.qml");
+
+    let config_path = PathBuf::from("build_config.json");
+
+    ensure_user_config_exists(&config_path);
+    validate_embedded_schema();
+    validate_default_config();
+    validate_user_config(&config_path);
+
+    let build_config = load_build_config(&config_path);
+    let profile_name = resolve_profile_name(&build_config);
+    let profile = resolve_profile(&build_config, &profile_name);
+
+    validate_profile_paths(profile, &profile_name);
+    apply_build_environment(profile);
+    apply_linker_settings(profile);
+
+    CxxQtBuilder::new_qml_module(QmlModule::new("com.sasedev.gstpreview01").qml_files(["qml/main.qml"]))
+        .qt_module("Core")
+        .qt_module("Qml")
+        .qt_module("Network")
+        .files(["src/bridge.rs"])
+        .build();
+
+    emit_runtime_hints(profile, &profile_name);
+}
diff --git a/poc005/build_config.default.json b/poc005/build_config.default.json
new file mode 100644
index 0000000..6a31de4
--- /dev/null
+++ b/poc005/build_config.default.json
@@ -0,0 +1,33 @@
+{
+    "active_profile": "sinus",
+    "profiles": {
+        "sinus": {
+            "qt": {
+                "qmake": "/home/sinus/DEV/Qt/6.11.0/gcc_64/bin/qmake",
+                "lib_dir": "/home/sinus/DEV/Qt/6.11.0/gcc_64/lib",
+                "qml_dir": "/home/sinus/DEV/Qt/6.11.0/gcc_64/qml",
+                "plugins_dir": "/home/sinus/DEV/Qt/6.11.0/gcc_64/plugins",
+                "version_major": 6
+            },
+            "link": {
+                "rpaths": [
+                    "/home/sinus/DEV/Qt/6.11.0/gcc_64/lib"
+                ]
+            }
+        },
+        "system": {
+            "qt": {
+                "qmake": "/usr/bin/qmake6",
+                "lib_dir": "/usr/lib/x86_64-linux-gnu",
+                "qml_dir": "/usr/lib/x86_64-linux-gnu/qt6/qml",
+                "plugins_dir": "/usr/lib/x86_64-linux-gnu/qt6/plugins",
+                "version_major": 6
+            },
+            "link": {
+                "rpaths": [
+                    "/usr/lib/x86_64-linux-gnu"
+                ]
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/poc005/qml/main.qml b/poc005/qml/main.qml
new file mode 100644
index 0000000..d2253bc
--- /dev/null
+++ b/poc005/qml/main.qml
@@ -0,0 +1,38 @@
+// file: poc-qt/poc005/qml/main.qml
+
+import QtQuick
+import QtQuick.Controls
+import QtQuick.Layouts
+import com.sasedev.gstpreview01
+
+ApplicationWindow {
+    visible: true
+    width: 600
+    height: 300
+    title: "POC005 - GStreamer Rust"
+
+    GstController {
+        id: gstController
+    }
+
+    ColumnLayout {
+        anchors.centerIn: parent
+        spacing: 12
+
+        Button {
+            text: "Start webcam (GStreamer)"
+            enabled: !gstController.started
+            onClicked: gstController.startPreview()
+        }
+
+        Button {
+            text: "Stop"
+            enabled: gstController.started
+            onClicked: gstController.stopPreview()
+        }
+
+        Label {
+            text: gstController.started ? "Started" : "Stopped"
+        }
+    }
+}
diff --git a/poc005/src/bridge.rs b/poc005/src/bridge.rs
new file mode 100644
index 0000000..2a43540
--- /dev/null
+++ b/poc005/src/bridge.rs
@@ -0,0 +1,80 @@
+// file: poc-qt/poc005/src/bridge.rs
+
+use core::pin::Pin;
+use gstreamer as gst;
+use gstreamer::prelude::*;
+
+#[derive(Default)]
+pub struct GstControllerRust {
+    started: bool,
+}
+
+#[cxx_qt::bridge]
+pub mod qobject {
+    extern "RustQt" {
+        #[qobject]
+        #[qml_element]
+        #[qproperty(bool, started)]
+        type GstController = super::GstControllerRust;
+
+        #[qinvokable]
+        #[cxx_name = "startPreview"]
+        fn start_preview(self: Pin<&mut GstController>);
+
+        #[qinvokable]
+        #[cxx_name = "stopPreview"]
+        fn stop_preview(self: Pin<&mut GstController>);
+    }
+}
+
+impl qobject::GstController {
+    pub fn start_preview(self: Pin<&mut Self>) {
+        if *self.started() {
+            println!("preview already started");
+            return;
+        }
+
+        if let Err(err) = gst::init() {
+            eprintln!("gst init failed: {err}");
+            return;
+        }
+
+        let pipeline_str = "v4l2src ! videoconvert ! fakesink";
+
+        let element = match gst::parse::launch(pipeline_str) {
+            Ok(v) => v,
+            Err(err) => {
+                eprintln!("failed to parse pipeline: {err}");
+                return;
+            }
+        };
+
+        let pipeline: gst::Pipeline = match element.downcast::<gst::Pipeline>() {
+            Ok(v) => v,
+            Err(_) => {
+                eprintln!("parsed element is not a gst::Pipeline");
+                return;
+            }
+        };
+
+        match pipeline.set_state(gst::State::Playing) {
+            Ok(_) => {
+                println!("pipeline started");
+                self.set_started(true);
+            }
+            Err(err) => {
+                eprintln!("failed to set pipeline to Playing: {err:?}");
+            }
+        }
+    }
+
+    pub fn stop_preview(self: Pin<&mut Self>) {
+        if !*self.started() {
+            println!("preview already stopped");
+            return;
+        }
+
+        self.set_started(false);
+        println!("pipeline stop requested");
+    }
+}
diff --git a/poc005/src/main.rs b/poc005/src/main.rs
new file mode 100644
index 0000000..4dccc95
--- /dev/null
+++ b/poc005/src/main.rs
@@ -0,0 +1,51 @@
+// file: poc-qt/poc005/src/main.rs
+
+mod bridge;
+
+use cxx_qt_lib::{QGuiApplication, QQmlApplicationEngine, QString, QUrl};
+use std::env;
+use std::path::PathBuf;
+
+fn main() {
+    let mut app = QGuiApplication::new();
+    let mut engine = QQmlApplicationEngine::new();
+
+    let current_dir = match env::current_dir() {
+        Ok(v) => v,
+        Err(err) => {
+            eprintln!("failed to get current_dir: {err}");
+            return;
+        }
+    };
+
+    let qml_path: PathBuf = current_dir.join("qml/main.qml");
+    let qml_path = match qml_path.canonicalize() {
+        Ok(v) => v,
+        Err(err) => {
+            eprintln!("failed to resolve qml/main.qml: {err}");
+            return;
+        }
+    };
+
+    let qml_path_str = match qml_path.to_str() {
+        Some(v) => v.to_string(),
+        None => {
+            eprintln!("qml path is not valid UTF-8: {}", qml_path.display());
+            return;
+        }
+    };
+
+    println!("loading qml from: {}", qml_path_str);
+
+    if let Some(engine_ref) = engine.as_mut() {
+        let url = QUrl::from_local_file(&QString::from(qml_path_str));
+        engine_ref.load(&url);
+    } else {
+        eprintln!("failed to create QQmlApplicationEngine");
+        return;
+    }
+
+    if let Some(app_ref) = app.as_mut() {
+        app_ref.exec();
+    }
+}