gchq/CyberChef · error · OperationError

Invalid file type

Error message

Invalid file type

What it means

Play Media's present() re-detects the file type with detectFileType(data) and requires types[0].mime to start with 'audio' or 'video' before building the <audio>/<video> element. This is a second guard after run() already validated with isType; it can fire when detection returns a non-media type first (detectFileType returns an ordered list and present() only inspects index 0) or when the data passed to present differs from what run validated.

Solutions

1. Ensure the data reaching present() is the same media bytes validated by run().
2. If the file has an ambiguous signature, re-encode it to a clean, unambiguous container.
3. Confirm the file is genuinely audio/video and not mis-detected due to truncation.
4. Treat both Play Media errors identically: the bytes are not recognised media.

import { detectFileType } from "../lib/FileType.mjs";
const types = detectFileType(data);
if (!types.length || !/^audio|video/.test(types[0].mime)) {
  throw new Error("Top detected type is not audio/video");
}

function topTypeIsMedia(data) {
  const types = detectFileType(data);
  return types.length > 0 && /^audio|video/.test(types[0].mime);
}

try {
  return await playMedia.present(data);
} catch (e) {
  if (e.message === "Invalid file type") {
    // detection disagrees with run(); re-encode to an unambiguous container
  }
  throw e;
}

When it happens

Trigger: detectFileType returns a list whose first entry is a non-media type even though isType earlier matched an audio/video type deeper in the list; present() is called with empty/changed data; a file that triggers ambiguous signatures where the top match is not media.

Common situations: A file with a magic sequence shared by a non-media format that sorts first in detection; chaining ops that alter the byte array between run and present; very short or ambiguous inputs.

Related errors

• Invalid or unrecognised file type
• Invalid file type.
• Error loading image.
• Invalid file format.
• Invalid file type.

AI-assisted analysis of gchq/CyberChef@4290ea7539 (2026-08-13). Data as JSON: /api/errors/dc3c8262ceb383bb. Report an issue: GitHub.

Appendix: source

Thrown at src/core/operations/PlayMedia.mjs:89

        }

        return input;
    }

    /**
     * Displays an audio or video element that may be able to play the media
     * file.
     *
     * @param {byteArray} data Data containing an audio or video file.
     * @returns {string} Markup to display a media player.
     */
    async present(data) {
        if (!data.length) return "";

        const types = detectFileType(data);
        const matches = /^audio|video/.exec(types[0].mime);
        if (!matches) {
            throw new OperationError("Invalid file type");
        }
        const dataURI = `data:${types[0].mime};base64,${toBase64(data)}`;
        const element = matches[0];

        let html = `<${element} src='${dataURI}' type='${types[0].mime}' controls>`;
        html += "<p>Unsupported media type.</p>";
        html += `</${element}>`;
        return html;
    }
}

export default PlayMedia;

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