fix(producer): correct short VFR frame coverage

packages/engine/src/index.ts

@@ -179,6 +179,7 @@ export {
   parseImageElements,
   extractVideoFramesRange,
   extractAllVideoFrames,
+  extractionFrameCountForDuration,
   resolveProjectRelativeSrc,
   getFrameAtTime,
   createFrameLookupTable,

packages/engine/src/services/videoFrameExtractor.test.ts

@@ -19,6 +19,7 @@ import {
   parseImageElements,
   extractAllVideoFrames,
   extractVideoFramesRange,
+  extractionFrameCountForDuration,
   createFrameLookupTable,
   resolveProjectRelativeSrc,
   resolveFrameFormat,
@@ -45,6 +46,22 @@ import { COMPLETE_SENTINEL, GC_MARKER, SCHEMA_PREFIX } from "./extractionCache.j
 // synthesized VFR fixture.
 const HAS_FFMPEG = spawnSync("ffmpeg", ["-version"]).status === 0;
 
+describe("extractionFrameCountForDuration", () => {
+  it("uses the same VFR ceil and CFR nearest-boundary rules as FFmpeg", () => {
+    expect(extractionFrameCountForDuration(0.466666, 30, true)).toBe(14);
+    expect(extractionFrameCountForDuration(0.466666, 30, false)).toBe(14);
+    expect(extractionFrameCountForDuration(0.616666, 30, true)).toBe(19);
+    expect(extractionFrameCountForDuration(0.616666, 30, false)).toBe(18);
+  });
+
+  it("fails closed for invalid durations and emits one frame for positive sub-frame work", () => {
+    expect(extractionFrameCountForDuration(Number.NaN, 30, true)).toBe(0);
+    expect(extractionFrameCountForDuration(1, 0, true)).toBe(0);
+    expect(extractionFrameCountForDuration(0, 30, true)).toBe(0);
+    expect(extractionFrameCountForDuration(0.001, 30, false)).toBe(1);
+  });
+});
+
 describe("video extraction failure taxonomy and bounded retry", () => {
   it("classifies missing and transient HTTP sources without exposing retry ambiguity", () => {
     expect(classifyVideoExtractionError(new Error("HTTP 404: Not Found"))).toMatchObject({
@@ -1558,6 +1575,29 @@ describe.skipIf(!HAS_FFMPEG)("extractAllVideoFrames on a VFR source", () => {
     expect(supersetDirNames(outputDir)).toEqual([]);
   }, 60_000);
 
+  it("uses VFR ceil frame counts when slicing overlapping short trims from a superset", async () => {
+    const outputDir = join(FIXTURE_DIR, "out-vfr-superset-short");
+    mkdirSync(outputDir, { recursive: true });
+
+    const result = await extractAllVideoFrames(
+      [
+        cfrClipElement("vfr-short-a", VFR_FIXTURE, 0.616666, 0),
+        cfrClipElement("vfr-short-b", VFR_FIXTURE, 0.616666, 0.1),
+      ],
+      FIXTURE_DIR,
+      { fps: 30, outputDir },
+    );
+
+    expect(result.errors).toEqual([]);
+    expect(extractedFor(result, "vfr-short-a").metadata.isVFR).toBe(true);
+    expect(extractedFor(result, "vfr-short-a").totalFrames).toBe(19);
+    expect(extractedFor(result, "vfr-short-b").totalFrames).toBe(19);
+    expect(statSync(framePath(result, "vfr-short-a", 3)).ino).toBe(
+      statSync(framePath(result, "vfr-short-b", 0)).ino,
+    );
+    expect(supersetDirNames(outputDir)).toEqual([]);
+  }, 60_000);
+
   it("publishes overlapping superset slices to cache entries and hits them on the next render", async () => {
     const CACHE_DIR = mkdtempSync(join(tmpdir(), "hf-extract-superset-cache-test-"));
     const SRC = await synthCfrClip("superset-cache-src.mp4", 10);

packages/engine/src/services/videoFrameExtractor.ts

@@ -77,6 +77,26 @@ export function isVideoFrameFormat(value: unknown): value is VideoFrameFormat {
   return typeof value === "string" && (VIDEO_FRAME_FORMATS as readonly string[]).includes(value);
 }
 
+/**
+ * Resolve the frame count produced for a requested extraction duration.
+ *
+ * CFR extraction uses FFmpeg's fps filter, whose end boundary rounds to the
+ * nearest frame. The VFR path normalizes with `-fps_mode cfr -r`, whose end
+ * boundary rounds up. Keep this calculation shared by superset slicing and
+ * producer coverage accounting so a complete VFR extraction cannot be
+ * rejected because the two paths disagree by one frame.
+ */
+export function extractionFrameCountForDuration(
+  durationSeconds: number,
+  fps: number,
+  isVFR: boolean,
+): number {
+  if (!Number.isFinite(durationSeconds) || !Number.isFinite(fps)) return 0;
+  if (durationSeconds <= 0 || fps <= 0) return 0;
+  const frames = isVFR ? Math.ceil(durationSeconds * fps) : Math.round(durationSeconds * fps);
+  return Math.max(1, frames);
+}
+
 export interface ExtractionOptions {
   fps: number;
   outputDir: string;
@@ -942,7 +962,11 @@ function sliceSupersetMember(
   // offset_i + k, so its source time is
   // baseStart + (offset_i + k) / fps = mediaStart_i + k / fps.
   // The frame-alignment precondition is what makes offset_i integral.
-  const requestedFrames = Math.round(work.videoDuration * fps);
+  const requestedFrames = extractionFrameCountForDuration(
+    work.videoDuration,
+    fps,
+    work.metadata.isVFR,
+  );
   const availableFrames = Math.max(0, superset.totalFrames - member.offsetFrames);
   const frameCount = Math.min(requestedFrames, availableFrames);
   for (let i = 0; i < frameCount; i += 1) {

packages/producer/src/services/render/videoFrameCoverage.test.ts

@@ -150,7 +150,7 @@ describe("computeVideoFrameCoverage", () => {
     expect(() => assertVideoFrameCoverage(reports, 0.95)).not.toThrow();
   });
 
-  it("keeps ceil coverage for the VFR extraction branch", () => {
+  it("tolerates a single FFmpeg boundary frame on a short 18/19 VFR extraction", () => {
     const videos = [makeVideo({ id: "short-vfr", start: 0, end: 0.616666 })];
     const reports = computeVideoFrameCoverage(
       videos,
@@ -162,7 +162,7 @@ describe("computeVideoFrameCoverage", () => {
       capturedFrames: 18,
       ratio: 18 / 19,
     });
-    expect(() => assertVideoFrameCoverage(reports, 0.95)).toThrow(VideoFrameCoverageError);
+    expect(() => assertVideoFrameCoverage(reports, 0.95)).not.toThrow();
   });
 
   it("still fails closed when a positive sub-frame clip captured zero frames", () => {
@@ -312,6 +312,86 @@ describe("assertVideoFrameCoverage", () => {
     expect(() => assertVideoFrameCoverage(reports, 0.95)).toThrow(VideoFrameCoverageError);
   });
 
+  it.each([
+    [13, 14],
+    [18, 19],
+  ])(
+    "tolerates exactly one nonzero boundary frame for a short clip (%i/%i)",
+    (capturedFrames, expectedFrames) => {
+      const reports = [
+        {
+          videoId: "short-boundary",
+          clipStart: 0,
+          clipEnd: expectedFrames / 30,
+          expectedFrames,
+          capturedFrames,
+          ratio: capturedFrames / expectedFrames,
+        },
+      ];
+      expect(() => assertVideoFrameCoverage(reports, 0.95)).not.toThrow();
+    },
+  );
+
+  it("does not treat a one-frame deficit as tolerance when it represents major loss", () => {
+    const reports = [
+      {
+        videoId: "major-loss",
+        clipStart: 0,
+        clipEnd: 2 / 30,
+        expectedFrames: 2,
+        capturedFrames: 1,
+        ratio: 0.5,
+      },
+    ];
+    expect(() => assertVideoFrameCoverage(reports, 0.95)).toThrow(VideoFrameCoverageError);
+  });
+
+  it("does not tolerate two missing frames, zero captured frames, or an exact threshold", () => {
+    const report = {
+      videoId: "short-incomplete",
+      clipStart: 0,
+      clipEnd: 19 / 30,
+      expectedFrames: 19,
+      capturedFrames: 17,
+      ratio: 17 / 19,
+    };
+    expect(() => assertVideoFrameCoverage([report], 0.95)).toThrow(VideoFrameCoverageError);
+    expect(() =>
+      assertVideoFrameCoverage([{ ...report, capturedFrames: 0, ratio: 0 }], 0.95),
+    ).toThrow(VideoFrameCoverageError);
+    expect(() =>
+      assertVideoFrameCoverage([{ ...report, capturedFrames: 18, ratio: 18 / 19 }], 1),
+    ).toThrow(VideoFrameCoverageError);
+  });
+
+  it("does not apply the one-frame tolerance to longer clips", () => {
+    const reports = [
+      {
+        videoId: "long-boundary",
+        clipStart: 0,
+        clipEnd: 21 / 30,
+        expectedFrames: 21,
+        capturedFrames: 20,
+        ratio: 20 / 21,
+      },
+    ];
+    expect(() => assertVideoFrameCoverage(reports, 0.99)).toThrow(VideoFrameCoverageError);
+  });
+
+  it("still rejects a material long-clip shortfall even when it is five frames", () => {
+    const reports = [
+      {
+        videoId: "long-partial",
+        clipStart: 0,
+        clipEnd: 89 / 30,
+        expectedFrames: 89,
+        capturedFrames: 84,
+        ratio: 84 / 89,
+      },
+    ];
+    expect(() => assertVideoFrameCoverage(reports, 0.95)).toThrow(VideoFrameCoverageError);
+  });
+
   it("respects a threshold override — 0.5 passes 60% coverage", () => {
     const reports = [
       {

packages/producer/src/services/render/videoFrameCoverage.ts

@@ -45,7 +45,14 @@
  */
 
 import { parseHTML } from "linkedom";
-import type { ExtractedFrames, VideoElement } from "@hyperframes/engine";
+import {
+  extractionFrameCountForDuration,
+  type ExtractedFrames,
+  type VideoElement,
+} from "@hyperframes/engine";
+
+const SHORT_CLIP_ONE_FRAME_TOLERANCE_MIN_EXPECTED_FRAMES = 14;
+const SHORT_CLIP_ONE_FRAME_TOLERANCE_MAX_EXPECTED_FRAMES = 20;
 
 export interface VideoFrameCoverageReport {
   videoId: string;
@@ -134,9 +141,20 @@ export function expectedFramesForClip(
   if (fps <= 0) return 0;
   const duration = Math.max(0, end - start);
   if (duration === 0) return 0;
-  const frameCount =
-    rounding === "nearest" ? Math.round(duration * fps) : Math.ceil(duration * fps);
-  return Math.max(1, frameCount);
+  return extractionFrameCountForDuration(duration, fps, rounding === "ceil");
+}
+
+function isToleratedShortClipBoundaryMiss(
+  report: VideoFrameCoverageReport,
+  threshold: number,
+): boolean {
+  return (
+    threshold < 1 &&
+    report.capturedFrames > 0 &&
+    report.expectedFrames >= SHORT_CLIP_ONE_FRAME_TOLERANCE_MIN_EXPECTED_FRAMES &&
+    report.expectedFrames <= SHORT_CLIP_ONE_FRAME_TOLERANCE_MAX_EXPECTED_FRAMES &&
+    report.expectedFrames - report.capturedFrames === 1
+  );
 }
 
 function expectedFramesForVideo(
@@ -203,7 +221,12 @@ export function assertVideoFrameCoverage(
   threshold: number | null,
 ): void {
   if (threshold === null) return;
-  const failed = reports.filter((report) => report.expectedFrames > 0 && report.ratio < threshold);
+  const failed = reports.filter(
+    (report) =>
+      report.expectedFrames > 0 &&
+      report.ratio < threshold &&
+      !isToleratedShortClipBoundaryMiss(report, threshold),
+  );
   if (failed.length === 0) return;
   // Sort ascending by ratio so the "worst" is first — that's what we cite
   // in the message and pin on the error details for telemetry.