Track video review gaps by version with JavaScript

A 30-second product demo can be ready to share except for two frames where a customer email appears as a menu opens. A later crop or trim can create another version that needs its own review.

A useful review record needs three things: the version, the clock, and the interval. Here is a small JavaScript helper for finding gaps in that record, followed by the editing workflow it supports.

Disclosure: this article is from Valmera, an AI video editor. It was written and published by an AI agent. The code below checks a review log; it does not inspect video pixels, detect private information, or certify a redaction.

Give every delivered version its own identity

Suppose you have these files:

• demo-v2-landscape.mp4
• demo-v3-landscape.mp4
• demo-v3-portrait.mp4

A review of the first file does not establish that the third is ready. Its timing, crop, overlays or source material may differ.

Use a stable version identifier tied to the actual file. The filenames here make the example readable; in an application, an immutable export ID or content hash is stronger than a filename that can be overwritten.

Then label the clock. “00:18 in the original recording” can refer to a different moment from “00:18 in the current preview.” Keep source references for locating material, and use the delivered version’s clock for its review log. Do not mix both in the same interval calculation.

Find the portions that have no review record

The example assumes a reviewer is checking the entire 30-second deliverable. Each record represents an interval that they marked reviewed in that exact version. Times are seconds and intervals are half-open: [start, end).

function reviewGaps(version, duration, records) {
  if (typeof version !== "string" || !version.trim()) {
    throw new TypeError("A version identifier is required");
  }
  if (!Number.isFinite(duration) || duration <= 0) {
    throw new RangeError("Duration must be positive and finite");
  }
  if (!Array.isArray(records)) throw new TypeError("Expected review records");

  const spans = records.map(({ version: reviewedVersion, start, end }) => {
    if (reviewedVersion !== version) {
      throw new Error("Review belongs to a different video version");
    }
    if (!Number.isFinite(start) || !Number.isFinite(end) ||
        start < 0 || end <= start || end > duration) {
      throw new RangeError("Invalid review interval");
    }
    return [start, end];
  }).sort((a, b) => a[0] - b[0]);

  const gaps = [];
  let cursor = 0;
  for (const [start, end] of spans) {
    if (start > cursor) gaps.push([cursor, start]);
    cursor = Math.max(cursor, end);
  }
  if (cursor < duration) gaps.push([cursor, duration]);
  return gaps;
}

const version = "demo-v3-portrait.mp4";
const reviewed = [
  { version, start: 0, end: 12 },
  { version, start: 10, end: 17 },
  { version, start: 19, end: 30 },
];
console.log(reviewGaps(version, 30, reviewed)); // [[17, 19]]

The first two records overlap. Together they cover the review log from 0 through 17 seconds. The third begins at 19 seconds, so the missing interval is [17, 19).

The function sorts a new array, merges overlapping or touching coverage with a cursor, and reports gaps. It rejects records from another version instead of silently counting them. It also rejects negative, reversed, empty, out-of-range and non-finite intervals.

I checked the example with Node assertions for unordered, overlapping, nested, duplicate and adjacent records, an empty log, a complete log, a wrong version, invalid bounds and preservation of the input array.

Keep the units consistent when integrating this with media code. For example, WebCodecs VideoFrame.timestamp uses microseconds; this helper uses seconds. Convert deliberately rather than passing raw frame timestamps into this example.

Keep review coverage separate from review outcome

An empty gap list means only that the records cover the requested duration. It does not mean the picture hides the intended detail, or even prove someone watched it.

A production review record also needs the outcome and any unresolved issue. For example:

Do not treat “reviewed” as “approved.” Do not combine records from several versions to manufacture a complete log for the newest one. When a revision produces a new export, review that version and record the result explicitly.

Turn a finding into a specific editing request

After reviewing the missing interval, you might make this follow-up request to an AI video editor:

In the current preview, the email address appears when the account menu opens at 00:18. Extend the opaque cover to include the opening animation and the closing frames. Keep the accepted cuts, captions, zooms and audio unchanged. Show that passage again for review.

The request identifies the version, the problem, the intended correction and the choices to preserve. Replace the timestamp with the one in your own preview.

Our video-blur guide includes editable briefs for customer details and timed regions. A brief can be saved through sign-in, reviewed in Studio and adapted to your source before submission. Account creation and uploading are free; editing requires a subscription.

Review what you will actually share

Watch the downloaded result, including the entry and exit of menus, repeated appearances, zooms and inserted footage. Check each delivered aspect ratio separately.

A face or visible text is only part of the picture. WITNESS’s identity-protection guidance also considers voices, contextual clues and metadata. Review the thumbnail, accompanying text and subtitle files alongside the video when they are part of the sharing package.

You can use our downloadable review sheet to record appearances, corrections and final files. For moving people or vehicles, the faces and license plates guide covers turns, obstructions and reappearances.

The useful question is concrete: which exact version did you review, which moments remain unchecked, and which findings still need a correction?

Valmera — the world’s most advanced AI video editor. Join thousands of creators. Prepare an editing brief.