diff --git a/Tests/TestResources/generate_prores422_10bit_test.sh b/Tests/TestResources/generate_prores422_10bit_test.sh
new file mode 100755
index 0000000..af086db
--- /dev/null
+++ b/Tests/TestResources/generate_prores422_10bit_test.sh
@@ -0,0 +1,39 @@
+#!/bin/bash
+# Generate a 10-bit ProRes 422 telecined test clip.
+#
+# This reproduces the source from issue: IVTC (vivtc.VFM) failing on >8-bit
+# input. ProRes 422 decodes to yuv422p10le (10-bit), which VFM rejects unless
+# the pipeline runs field matching on an 8-bit copy and emits full-depth pixels
+# via VFM's clip2 parameter.
+#
+# Properties (matching the reported source):
+#   - Codec: Apple ProRes 422 (Standard, apcn)
+#   - Pixel format: yuv422p10le (10-bit)
+#   - Field order: top field first (interlaced / telecined)
+#   - Resolution: 720x480 (NTSC), 29.97fps, ~1s (30 frames = 6 3:2 cycles)
+#
+# Drop the resulting .mov into the app and run Deinterlace > IVTC (or a preview)
+# to exercise the high-bit-depth path.
+#
+# Usage: ./generate_prores422_10bit_test.sh [output_dir]
+
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+OUTPUT_DIR="${1:-$SCRIPT_DIR}"
+SOURCE="$SCRIPT_DIR/hard_telecine_test.avi"
+OUTPUT="$OUTPUT_DIR/prores422_10bit_telecine.mov"
+
+if [ ! -f "$SOURCE" ]; then
+  echo "Missing $SOURCE — run ./generate_telecine_test.sh first." >&2
+  exit 1
+fi
+
+ffmpeg -y -i "$SOURCE" \
+  -frames:v 30 \
+  -c:v prores_ks -profile:v 2 -vendor apl0 -pix_fmt yuv422p10le \
+  -flags +ildct+ilme -top 1 \
+  "$OUTPUT"
+
+echo "Wrote $OUTPUT"
+ffmpeg -i "$OUTPUT" 2>&1 | grep -E "Stream|Duration" || true
diff --git a/Tests/TestResources/prores422_10bit_telecine.mov b/Tests/TestResources/prores422_10bit_telecine.mov
new file mode 100644
index 0000000..513dbff
Binary files /dev/null and b/Tests/TestResources/prores422_10bit_telecine.mov differ
diff --git a/app/test/integration_filter_parameters_test.dart b/app/test/integration_filter_parameters_test.dart
index 569e9fd..6a0d734 100644
--- a/app/test/integration_filter_parameters_test.dart
+++ b/app/test/integration_filter_parameters_test.dart
@@ -151,6 +151,7 @@ void validateParams({
 
 VideoJob buildJob({
   required String testName,
+  QTGMCParameters? deinterlace,
   NoiseReductionParameters? noiseReduction,
   DehaloParameters? dehalo,
   DeblockParameters? deblock,
@@ -165,7 +166,7 @@ VideoJob buildJob({
   inputPath: TestConfig.inputFile,
   outputPath: '${TestConfig.outputDir}/$testName.mkv',
   processingPipeline: ProcessingPipeline(
-    deinterlace: const QTGMCParameters(enabled: false),
+    deinterlace: deinterlace ?? const QTGMCParameters(enabled: false),
     descratch: descratch ?? const DeScratchParameters(),
     spotless: spotless ?? const SpotLessParameters(),
     noiseReduction: noiseReduction ?? const NoiseReductionParameters(),
@@ -436,5 +437,25 @@ void main() {
       expect(actual['pel'], '1');
       print('  PASS');
     }, timeout: const Timeout(Duration(minutes: 2)));
+
+    // --- IVTC (core.vivtc.VFM + VDecimate) high-bit-depth guard ---
+    // VFM only accepts 8-bit YUV/GRAY, so IVTC on a 10-bit source (e.g. ProRes
+    // 422, yuv422p10le) must run field matching on an 8-bit metrics copy while
+    // emitting full-depth pixels via clip2. Assert that wiring is in the script.
+    test('ivtc: VFM/VDecimate 8-bit guard + clip2', () async {
+      final job = buildJob(
+        testName: 'ivtc_guard',
+        deinterlace: const QTGMCParameters(
+          enabled: true, method: DeinterlaceMethod.ivtc, tff: true,
+        ),
+      );
+      print('  Generating IVTC script...');
+      final script = await generateScriptViaWorker(job);
+      expect(script, contains('bits_per_sample == 8'));
+      expect(script, contains('core.vivtc.VFM(_ivtc_metrics'));
+      expect(script, contains('clip2=_ivtc_src'));
+      expect(script, contains('core.vivtc.VDecimate(clip'));
+      print('  PASS');
+    }, timeout: const Timeout(Duration(minutes: 2)));
   });
 }
diff --git a/app/test/integration_high_bit_depth_test.dart b/app/test/integration_high_bit_depth_test.dart
new file mode 100644
index 0000000..a8a3934
--- /dev/null
+++ b/app/test/integration_high_bit_depth_test.dart
@@ -0,0 +1,100 @@
+/// Full-encode regression test for IVTC on a >8-bit source.
+///
+/// vivtc.VFM only accepts 8-bit YUV/GRAY, so IVTC on a 10-bit source such as
+/// ProRes 422 (yuv422p10le) previously failed at vspipe evaluation with
+/// "VFM: input clip must be constant format YUV420P8, ...". The fix runs field
+/// matching on an 8-bit metrics copy while emitting the full-depth pixels via
+/// VFM's clip2 parameter. This test runs the worker end-to-end on the committed
+/// 10-bit ProRes fixture and asserts a valid output — it fails on the pre-fix
+/// pipeline (the encode aborts) and passes with the guard in place.
+///
+/// The fixture (Tests/TestResources/prores422_10bit_telecine.mov) is produced
+/// by Tests/TestResources/generate_prores422_10bit_test.sh.
+///
+/// Heavy (full-encode) — runs in the nightly workflow, not the push gate.
+@Tags(['heavy'])
+library;
+
+// ignore_for_file: avoid_print — these tests print diagnostics to the test log.
+
+import 'dart:io';
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:uuid/uuid.dart';
+
+import 'package:vapourbox/models/encoding_settings.dart';
+import 'package:vapourbox/models/processing_pipeline.dart';
+import 'package:vapourbox/models/qtgmc_parameters.dart';
+import 'package:vapourbox/models/video_job.dart';
+
+import 'support/worker_harness.dart';
+
+String get _outDir => '${WorkerHarness.outputDir}/high_bit_depth';
+String get _proResFixture =>
+    '${WorkerHarness.repoRoot}/Tests/TestResources/prores422_10bit_telecine.mov';
+
+void main() {
+  setUpAll(() async {
+    await WorkerHarness.ensureReady();
+    await Directory(_outDir).create(recursive: true);
+  });
+
+  group('IVTC on high-bit-depth source (full encode)', () {
+    test('IVTC runs end-to-end on 10-bit ProRes 422 (yuv422p10le)', () async {
+      expect(File(_proResFixture).existsSync(), isTrue,
+          reason: 'fixture missing — run generate_prores422_10bit_test.sh');
+
+      // Probe the fixture the way the app does before building a job, so the
+      // worker's pipe decoder gets the right dimensions/format. Confirm it is
+      // genuinely a >8-bit source (otherwise the test would not exercise the
+      // VFM 8-bit guard).
+      final src = await WorkerHarness.firstStream(_proResFixture,
+          selector: 'v:0',
+          entries: ['pix_fmt', 'width', 'height', 'nb_read_frames'],
+          countFrames: true);
+      expect(src, isNotNull);
+      final pixFmt = src!['pix_fmt'] as String;
+      print('  fixture: $pixFmt ${src['width']}x${src['height']} '
+          '${src['nb_read_frames']} frames');
+      expect(pixFmt, contains('10'),
+          reason: 'fixture must be >8-bit to exercise the VFM guard');
+
+      final frames = int.parse(src['nb_read_frames'] as String);
+      final job = VideoJob(
+        id: const Uuid().v4(),
+        inputPath: _proResFixture,
+        outputPath: '$_outDir/ivtc_10bit.mkv',
+        processingPipeline: const ProcessingPipeline(
+          deinterlace: QTGMCParameters(
+            enabled: true,
+            method: DeinterlaceMethod.ivtc,
+            tff: true,
+          ),
+        ),
+        encodingSettings: const EncodingSettings(
+          codec: VideoCodec.h264,
+          container: ContainerFormat.mkv,
+          audioMode: AudioMode.none,
+        ),
+        detectedFieldOrder: FieldOrder.topFieldFirst,
+        totalFrames: frames,
+        inputFrameRate: 29.97,
+        inputWidth: int.parse(src['width'].toString()),
+        inputHeight: int.parse(src['height'].toString()),
+        inputPixelFormat: pixFmt,
+      );
+
+      final result =
+          await WorkerHarness.runJob(job.toJson(), label: 'ivtc_10bit');
+      expect(result.success, isTrue, reason: result.error);
+      expect(File(result.outputPath!).existsSync(), isTrue,
+          reason: 'output file should exist');
+
+      final out = await WorkerHarness.firstStream(result.outputPath!,
+          selector: 'v:0', entries: ['codec_name', 'width', 'height']);
+      expect(out, isNotNull, reason: 'output should contain a video stream');
+      print('  output video: ${out?['codec_name']} '
+          '${out?['width']}x${out?['height']}');
+    }, timeout: const Timeout(Duration(minutes: 5)));
+  });
+}
diff --git a/worker/templates/pipeline_template.vpy b/worker/templates/pipeline_template.vpy
index 03f58d0..3a76a81 100644
--- a/worker/templates/pipeline_template.vpy
+++ b/worker/templates/pipeline_template.vpy
@@ -296,7 +296,13 @@ clip = haf.QTGMC(
 {{/DEINT_QTGMC}}
 {{#DEINT_IVTC}}
 # IVTC: Inverse Telecine (VFM field matching + VDecimate)
-clip = core.vivtc.VFM(clip, order={{IVTC_ORDER}},
+# VFM only accepts 8-bit YUV/GRAY. For higher bit-depth sources (e.g. 10-bit
+# ProRes 422, yuv422p10le) run the field-matching/decimation decisions on an
+# 8-bit copy but take the output pixels from the full-depth clip via clip2, so
+# no precision is lost.
+_ivtc_src = clip
+_ivtc_metrics = clip if clip.format.bits_per_sample == 8 else core.resize.Bilinear(clip, format=clip.format.replace(bits_per_sample=8, sample_type=vs.INTEGER))
+clip = core.vivtc.VFM(_ivtc_metrics, order={{IVTC_ORDER}},
 {{#IVTC_MODE}}
     mode={{IVTC_MODE}},
 {{/IVTC_MODE}}
@@ -312,7 +318,8 @@ clip = core.vivtc.VFM(clip, order={{IVTC_ORDER}},
 {{#IVTC_BLOCK_Y}}
     blocky={{IVTC_BLOCK_Y}},
 {{/IVTC_BLOCK_Y}}
-)
+    clip2=_ivtc_src)
+# VFM output is full-depth again; VDecimate accepts 8..16 bit natively.
 clip = core.vivtc.VDecimate(clip,
 {{#IVTC_CYCLE}}
     cycle={{IVTC_CYCLE}},
diff --git a/worker/templates/preview_template.vpy b/worker/templates/preview_template.vpy
index faed109..23f9dc2 100644
--- a/worker/templates/preview_template.vpy
+++ b/worker/templates/preview_template.vpy
@@ -273,7 +273,12 @@ clip = haf.QTGMC(
 {{/DEINT_QTGMC}}
 {{#DEINT_IVTC}}
 # IVTC Preview: VFM field matching only (no VDecimate for single-frame preview)
-clip = core.vivtc.VFM(clip, order={{IVTC_ORDER}},
+# VFM only accepts 8-bit YUV/GRAY. For higher bit-depth sources (e.g. 10-bit
+# ProRes 422, yuv422p10le) run the field matching on an 8-bit copy but take the
+# output pixels from the full-depth clip via clip2, so no precision is lost.
+_ivtc_src = clip
+_ivtc_metrics = clip if clip.format.bits_per_sample == 8 else core.resize.Bilinear(clip, format=clip.format.replace(bits_per_sample=8, sample_type=vs.INTEGER))
+clip = core.vivtc.VFM(_ivtc_metrics, order={{IVTC_ORDER}},
 {{#IVTC_MODE}}
     mode={{IVTC_MODE}},
 {{/IVTC_MODE}}
@@ -289,7 +294,7 @@ clip = core.vivtc.VFM(clip, order={{IVTC_ORDER}},
 {{#IVTC_BLOCK_Y}}
     blocky={{IVTC_BLOCK_Y}},
 {{/IVTC_BLOCK_Y}}
-)
+    clip2=_ivtc_src)
 {{/DEINT_IVTC}}
 {{/DEINTERLACE}}
 
diff --git a/worker/tests/filter_integration_test.rs b/worker/tests/filter_integration_test.rs
index ae2fb16..63026d2 100644
--- a/worker/tests/filter_integration_test.rs
+++ b/worker/tests/filter_integration_test.rs
@@ -1977,3 +1977,26 @@ fn test_56_frame_count_mapping() {
     assert_eq!(span.start, 10);
     assert!(span.exact);
 }
+
+#[test]
+fn test_57_ivtc_high_bit_depth_guard() {
+    // VFM only accepts 8-bit YUV/GRAY, so IVTC on a higher bit-depth source
+    // (e.g. 10-bit ProRes 422, yuv422p10le) must run field matching on an 8-bit
+    // metrics copy while emitting full-depth pixels via clip2. Verify the guard
+    // and clip2 wiring appear in the generated script. (The telecine fixture is
+    // 8-bit, so this also confirms the guarded path still runs end-to-end.)
+    create_output_dir();
+
+    let mut job = create_ivtc_base_job("test_57_ivtc_high_bit_depth_guard");
+    job.processing_pipeline = Some(ProcessingPipeline {
+        deinterlace: job.qtgmc_parameters.clone(),
+        ..ProcessingPipeline::default()
+    });
+
+    run_job_and_verify(&job, "IVTC - High Bit Depth Guard", &[
+        "bits_per_sample == 8",
+        "core.vivtc.VFM(_ivtc_metrics",
+        "clip2=_ivtc_src",
+        "core.vivtc.VDecimate(clip",
+    ]).unwrap();
+}