fix(nodes): register HW codec nodes, fix i420_to_nv12 truncation, remove dead code

- Add cfg-gated registration calls for vulkan_video, vaapi, and nvcodec
  nodes in register_video_nodes() — without these, users enabling the
  features would get 'node not found' errors at runtime.
- Fix i420_to_nv12 in vulkan_video.rs to use div_ceil(2) for chroma
  dimensions instead of truncating integer division (h/2, w/2), matching
  the correct implementation in nv_av1.rs.
- Update HwAccelMode::Auto doc comment to accurately reflect that
  HW-only nodes do not implement CPU fallback — Auto and ForceHw
  behave identically; CPU fallback is achieved by selecting a different
  (software) node at the pipeline level.
- Remove dead default_quality() and default_framerate() functions in
  vaapi_av1.rs (unused — the struct uses a manual Default impl).
- Add registration regression tests to nv_av1 and vaapi_av1 modules.

Signed-off-by: StreamKit Devin <devin@streamkit.dev>
Co-Authored-By: Claudio Costa <cstcld91@gmail.com>

Author: streamkit-devin

crates/nodes/src/video/mod.rs

@@ -84,7 +84,12 @@ pub const H264_CONTENT_TYPE: &str = "video/h264";
 )]
 #[serde(rename_all = "lowercase")]
 pub enum HwAccelMode {
-    /// Auto-detect: use HW if available, fall back to CPU otherwise.
+    /// Auto-detect: attempt hardware acceleration.
+    ///
+    /// For HW-only nodes (Vulkan Video, VA-API, NVENC/NVDEC) this behaves
+    /// identically to `ForceHw` — the node will fail if the required
+    /// hardware is unavailable.  CPU fallback is achieved by selecting a
+    /// different (software) node at the pipeline level.
     #[default]
     Auto,
     /// Force HW acceleration — fail if unavailable.
@@ -631,4 +636,13 @@ pub fn register_video_nodes(registry: &mut NodeRegistry, constraints: &GlobalNod
 
     #[cfg(feature = "dav1d")]
     dav1d::register_dav1d_nodes(registry);
+
+    #[cfg(feature = "vulkan_video")]
+    vulkan_video::register_vulkan_video_nodes(registry);
+
+    #[cfg(feature = "vaapi")]
+    vaapi_av1::register_vaapi_av1_nodes(registry);
+
+    #[cfg(feature = "nvcodec")]
+    nv_av1::register_nv_av1_nodes(registry);
 }

crates/nodes/src/video/nv_av1.rs

@@ -1182,4 +1182,21 @@ mod tests {
             }
         }
     }
+
+    // ── Registration test ────────────────────────────────────────────────
+
+    #[test]
+    fn test_node_registration() {
+        let mut registry = NodeRegistry::new();
+        register_nv_av1_nodes(&mut registry);
+
+        assert!(
+            registry.create_node("video::nv::av1_decoder", None).is_ok(),
+            "NV AV1 decoder should be registered"
+        );
+        assert!(
+            registry.create_node("video::nv::av1_encoder", None).is_ok(),
+            "NV AV1 encoder should be registered"
+        );
+    }
 }

crates/nodes/src/video/vaapi_av1.rs

@@ -747,14 +747,6 @@ pub struct VaapiAv1EncoderConfig {
     pub hw_accel: HwAccelMode,
 }
 
-const fn default_quality() -> u32 {
-    DEFAULT_QUALITY
-}
-
-const fn default_framerate() -> u32 {
-    DEFAULT_FRAMERATE
-}
-
 impl Default for VaapiAv1EncoderConfig {
     fn default() -> Self {
         Self {
@@ -1804,4 +1796,21 @@ mod tests {
         let result: Result<VaapiAv1EncoderConfig, _> = serde_json::from_str(json);
         assert!(result.is_err(), "Unknown fields should be rejected");
     }
+
+    // ── Registration test ────────────────────────────────────────────────
+
+    #[test]
+    fn test_node_registration() {
+        let mut registry = NodeRegistry::new();
+        register_vaapi_av1_nodes(&mut registry);
+
+        assert!(
+            registry.create_node("video::vaapi::av1_decoder", None).is_ok(),
+            "VA-API AV1 decoder should be registered"
+        );
+        assert!(
+            registry.create_node("video::vaapi::av1_encoder", None).is_ok(),
+            "VA-API AV1 encoder should be registered"
+        );
+    }
 }

crates/nodes/src/video/vulkan_video.rs

@@ -737,9 +737,11 @@ fn i420_to_nv12(frame: &VideoFrame) -> Vec<u8> {
     let h = frame.height as usize;
     let layout = frame.layout();
 
+    let chroma_w = w.div_ceil(2);
+    let chroma_h = h.div_ceil(2);
+    let uv_row_bytes = chroma_w * 2;
     let y_size = w * h;
-    let uv_size = w * (h / 2);
-    let mut nv12 = vec![0u8; y_size + uv_size];
+    let mut nv12 = vec![0u8; y_size + uv_row_bytes * chroma_h];
 
     let src = frame.data.as_slice();
     let planes = layout.planes();
@@ -756,12 +758,10 @@ fn i420_to_nv12(frame: &VideoFrame) -> Vec<u8> {
     }
 
     // Interleave U and V into NV12 UV plane.
-    let chroma_h = h / 2;
-    let chroma_w = w / 2;
     for row in 0..chroma_h {
         let u_src_start = u_plane.offset + row * u_plane.stride;
         let v_src_start = v_plane.offset + row * v_plane.stride;
-        let dst_start = y_size + row * w;
+        let dst_start = y_size + row * uv_row_bytes;
         for col in 0..chroma_w {
             nv12[dst_start + col * 2] = src[u_src_start + col];
             nv12[dst_start + col * 2 + 1] = src[v_src_start + col];