Automatic Video Frame Resizing in edgeimpulsevideoinfer (#29)

This PR enhances the `edgeimpulsevideoinfer` GStreamer element to automatically handle video frame resizing internally, eliminating the need for users to manually resize frames before inference.

Previously, users were required to ensure video frames matched the ML model's expected input dimensions (e.g., 224x224). This forced complex GStreamer pipelines with external `videoscale` elements and manual resolution management:

```bash
# Old approach - complex pipeline with manual resizing
gst-launch-1.0 qtiqmmfsrc camera=0 ! video/x-raw,format=NV12,width=1920,height=1080,framerate=30/1 ! \
  videoconvert ! videoscale ! video/x-raw,format=RGB,width=224,height=224 ! \
  edgeimpulsevideoinfer threshold="3.minScore=0.5" ! edgeimpulseoverlay ! \
  videoconvert ! videoscale ! video/x-raw,format=RGB,width=1920,height=1080 ! \
  waylandsink display="wayland-1" sync=false fullscreen=true
```

```bash
# New approach - clean, simple pipeline
gst-launch-1.0 qtiqmmfsrc camera=0 ! video/x-raw,format=NV12,width=1920,height=1080,framerate=30/1 ! \
  videoconvert ! edgeimpulsevideoinfer threshold="3.minScore=0.5" ! \
  edgeimpulseoverlay ! waylandsink display="wayland-1" sync=false fullscreen=true
```

Author: ferjm

README.md

@@ -1,3 +1,24 @@
 fn main() {
+    // Set PKG_CONFIG_PATH to include all necessary directories for macOS
+    if cfg!(target_os = "macos") {
+        let homebrew_prefix = "/opt/homebrew";
+        let pkg_config_paths = vec![
+            format!("{}/opt/libxml2/lib/pkgconfig", homebrew_prefix),
+            format!("{}/lib/pkgconfig", homebrew_prefix),
+            format!("{}/share/pkgconfig", homebrew_prefix),
+        ];
+
+        let existing_path = std::env::var("PKG_CONFIG_PATH").unwrap_or_default();
+        let new_path = if existing_path.is_empty() {
+            pkg_config_paths.join(":")
+        } else {
+            format!("{}:{}", pkg_config_paths.join(":"), existing_path)
+        };
+
+        println!("cargo:warning=Setting PKG_CONFIG_PATH to: {}", new_path);
+        std::env::set_var("PKG_CONFIG_PATH", &new_path);
+        println!("cargo:rerun-if-env-changed=PKG_CONFIG_PATH");
+    }
+
     gst_plugin_version_helper::info()
 }

build.rs

@@ -8,7 +8,7 @@
 //!   # FFI mode (default, no model path needed):
 //!   cargo run --example audio_inference [OPTIONS]
 //!
-//!   # EIM mode (legacy, requires model path):
+//!   # EIM mode (requires model path):
 //!   cargo run --example audio_inference -- --model <path_to_model> [OPTIONS]
 //!
 //! Optional arguments:
@@ -37,7 +37,7 @@ use std::path::Path;
 /// Command line parameters for the real-time audio classification example
 #[derive(Parser, Debug)]
 struct AudioClassifyParams {
-    /// Path to the Edge Impulse model file (.eim) - EIM mode only (legacy)
+    /// Path to the Edge Impulse model file (.eim) - EIM mode only
     #[clap(short, long)]
     model: Option<String>,
 

examples/audio_inference.rs

@@ -5,13 +5,17 @@
 //! This example demonstrates how to use the Edge Impulse GStreamer plugin to perform
 //! image classification using a trained model on a single image file.
 //!
+//! The edgeimpulsevideoinfer element automatically handles frame resizing to match model
+//! input requirements and scales detection results back to the original resolution.
+//!
 //! Usage:
 //!   # EIM mode (requires model path):
 //!   cargo run --example image_inference -- --model <path_to_model> --image <path_to_image>
 //!
 //!   # FFI mode (no model path needed):
 //!   cargo run --example image_inference -- --image <path_to_image>
 //!
+//!
 //! Environment setup:
 //! export GST_PLUGIN_PATH="target/debug:$GST_PLUGIN_PATH"
 
@@ -42,14 +46,6 @@ struct ImageClassifyParams {
     #[arg(short, long, default_value = "RGB")]
     format: String,
 
-    /// Input width
-    #[arg(short = 'W', long, default_value = "96")]
-    width: i32,
-
-    /// Input height
-    #[arg(short = 'H', long, default_value = "96")]
-    height: i32,
-
     /// Enable debug output
     #[arg(short, long)]
     debug: bool,
@@ -103,8 +99,6 @@ fn create_pipeline(args: &ImageClassifyParams) -> Result<gst::Pipeline, Box<dyn
             "caps",
             &gst::Caps::builder("video/x-raw")
                 .field("format", &args.format)
-                .field("width", &args.width)
-                .field("height", &args.height)
                 .build(),
         )
         .build()?;
@@ -222,7 +216,6 @@ fn example_main() -> Result<(), Box<dyn Error>> {
     if let Some(output) = &args.output {
         println!("💾 Output image: {}", output);
     }
-    println!("📐 Image dimensions: {}x{}", args.width, args.height);
     println!("🎨 Format: {}", args.format);
     println!("🔧 Debug mode: {}", args.debug);
 

examples/image_inference.rs

@@ -13,6 +13,7 @@ use image::io::Reader as ImageReader;
 use image::ImageFormat;
 
 /// A GStreamer-based image slideshow that runs inference on images from a folder.
+/// The edgeimpulsevideoinfer element automatically handles frame resizing to match model requirements.
 #[derive(Parser, Debug)]
 #[command(author, version, about, long_about = None)]
 struct Args {
@@ -28,14 +29,6 @@ struct Args {
     #[arg(short = 'n', long, default_value = "100")]
     max_images: usize,
 
-    /// Input width
-    #[arg(short = 'W', long)]
-    width: i32,
-
-    /// Input height
-    #[arg(short = 'H', long)]
-    height: i32,
-
     /// Slideshow framerate (images per second, default: 1)
     #[arg(long, default_value = "1")]
     framerate: i32,
@@ -187,7 +180,7 @@ fn example_main() -> Result<()> {
         .property("max-size-buffers", 1u32)
         .property("max-size-time", 30000000000u64)
         .build()?;
-    let videoscale = ElementFactory::make("videoscale").build()?;
+    // videoscale removed - edgeimpulsevideoinfer now handles resizing
     let videorate = ElementFactory::make("videorate")
         .property("max-rate", args.framerate)
         .build()?;
@@ -203,18 +196,15 @@ fn example_main() -> Result<()> {
         .build()?;
 
     // Set caps for GRAY8 before inference, including framerate to control slideshow speed
+    // The edgeimpulsevideoinfer element will automatically resize to match model requirements
     let caps_gray = gstreamer::Caps::builder("video/x-raw")
         .field("format", "GRAY8")
-        .field("width", args.width)
-        .field("height", args.height)
         .field("framerate", &gstreamer::Fraction::new(args.framerate, 1))
         .build();
     capsfilter_gray.set_property("caps", &caps_gray);
 
     let caps_rgb = gstreamer::Caps::builder("video/x-raw")
         .field("format", "RGB")
-        .field("width", args.width)
-        .field("height", args.height)
         .build();
     capsfilter_rgb.set_property("caps", &caps_rgb);
 
@@ -223,7 +213,6 @@ fn example_main() -> Result<()> {
         &decodebin,
         &videoconvert1,
         &queue,
-        &videoscale,
         &videorate,
         &capsfilter_gray,
         &edgeimpulse,
@@ -259,7 +248,6 @@ fn example_main() -> Result<()> {
     Element::link_many([
         &videoconvert1,
         &queue,
-        &videoscale,
         &videorate,
         &capsfilter_gray,
         &edgeimpulse,