Fix false telecine detection on VHS tapes, bump version to 0.7.1

Scan type detection was misclassifying interlaced PAL VHS content as hard
telecine because any single repeated field (repeatedFields > 0) triggered
telecine. VHS tapes produce stray repeated fields from tracking instability,
especially at the start. Now requires >= 15% repeated fields ratio, matching
real 3:2 pulldown (~40%) while filtering out VHS noise. Also skips the first
2s of longer videos to avoid unstable VHS leader sections.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: StuartCameronCode

app/lib/services/field_order_detector.dart

@@ -85,7 +85,7 @@ class FieldOrderDetector {
 
       // Run idet and repeat_pict analysis in parallel
       final results = await Future.wait([
-        _runIdet(videoPath),
+        _runIdet(videoPath, duration: duration),
         _detectSoftTelecine(videoPath),
       ]);
       final idet = results[0] as _IdetResult?;
@@ -132,14 +132,21 @@ class FieldOrderDetector {
   /// - Interlaced vs progressive content
   /// - Field order (TFF/BFF)
   /// - Repeated fields (indicates hard telecine)
-  Future<_IdetResult?> _runIdet(String videoPath) async {
+  ///
+  /// When [duration] is known and > 4s, skips the first 2s to avoid
+  /// VHS leader/tracking instability.
+  Future<_IdetResult?> _runIdet(String videoPath, {double? duration}) async {
     final ffmpeg = ToolLocator.instance.ffmpegPath;
     if (ffmpeg == null) return null;
 
+    // Skip first 2s for longer videos to avoid VHS leader/tracking instability
+    final skipSeconds = (duration != null && duration > 4.0) ? 2 : 0;
+
     try {
       final result = await Process.run(
         ffmpeg,
         [
+          if (skipSeconds > 0) ...['-ss', '$skipSeconds'],
           '-i', videoPath,
           '-vf', 'idet',
           '-frames:v', '200',
@@ -251,8 +258,12 @@ class FieldOrderDetector {
       }
     }
 
-    // Hard telecine: interlaced frames with significant repeated fields
-    if (interlacedRatio > 0.5 && repeatedFields > 0) {
+    // Hard telecine: interlaced frames with significant repeated fields.
+    // True 3:2 pulldown shows ~40% repeated fields, 2:2 shows ~50%.
+    // Require at least 15% to avoid false positives from VHS tracking
+    // artifacts or other analog noise (especially at tape start).
+    final repeatedRatio = total > 0 ? repeatedFields / total : 0.0;
+    if (interlacedRatio > 0.5 && repeatedRatio > 0.15) {
       return ScanType.telecine;
     }
 

app/macos/Runner/Info.plist

@@ -17,9 +17,9 @@
 	<key>CFBundlePackageType</key>
 	<string>APPL</string>
 	<key>CFBundleShortVersionString</key>
-	<string>0.7.0</string>
+	<string>0.7.1</string>
 	<key>CFBundleVersion</key>
-	<string>0.7.0</string>
+	<string>0.7.1</string>
 	<key>LSMinimumSystemVersion</key>
 	<string>$(MACOSX_DEPLOYMENT_TARGET)</string>
 	<key>NSHumanReadableCopyright</key>

app/pubspec.yaml

@@ -1,7 +1,7 @@
 name: vapourbox
 description: "Video restoration and cleanup powered by VapourSynth"
 publish_to: 'none'
-version: 0.7.0+12
+version: 0.7.1+13
 
 environment:
   sdk: ^3.6.2

app/windows/runner/Runner.rc

@@ -73,8 +73,8 @@ IDI_APP_ICON            ICON                    "resources\\app_icon.ico"
 #endif
 
 VS_VERSION_INFO VERSIONINFO
- FILEVERSION 0,7,0,0
- PRODUCTVERSION 0,7,0,0
+ FILEVERSION 0,7,1,0
+ PRODUCTVERSION 0,7,1,0
  FILEFLAGSMASK VS_FFI_FILEFLAGSMASK
 #ifdef _DEBUG
  FILEFLAGS VS_FF_DEBUG

worker/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "vapourbox-worker"
-version = "0.7.0"
+version = "0.7.1"
 edition = "2021"
 description = "Video restoration worker using VapourSynth"
 authors = ["Stuart Cameron"]