BoundaryML/baml · error · Error

Video is not base64

Error message

Video is not base64

What it means

JavaScript (compiled) version of Video.asBase64(): throws when this.type !== "base64", i.e. the video is URL-backed. Returns [base64Data, mediaType] only for base64-stored videos. Same semantics as the TypeScript source in typescript_src/video.ts.

Source

Thrown at engine/language_client_typescript/video.js:79

    }
    /**
     * Get the URL of the video if it's stored as a URL
     * @throws Error if the video is not stored as a URL
     */
    asUrl() {
        if (!this.isUrl()) {
            throw new Error("Video is not a URL");
        }
        return this.content;
    }
    /**
     * Get the base64 data and media type if the video is stored as base64
     * @returns [base64Data, mediaType]
     * @throws Error if the video is not stored as base64
     */
    asBase64() {
        if (this.type !== "base64") {
            throw new Error("Video is not base64");
        }
        return [this.content, this.mediaType || ""];
    }
    /**
     * Convert the video to a JSON representation
     */
    toJSON() {
        if (this.type === "url") {
            return { url: this.content };
        }
        return {
            base64: this.content,
            media_type: this.mediaType || "",
        };
    }
}
exports.BamlVideo = BamlVideo;

View on GitHub (pinned to bd85ce9dee)

Solutions

1. Check video.type === "base64" (or !video.isUrl()) before calling asBase64()
2. Download the URL content and encode to base64 yourself before calling base64-only APIs
3. Store the video as base64 at construction time when the downstream consumer requires it
4. Write a normalizeVideo helper that handles both representations once

Example fix

// before
const [data, mediaType] = video.asBase64();
// after
const [data, mediaType] = video.isUrl()
  ? await videoToBase64(video.asUrl())
  : video.asBase64();

if (!video || video.type !== "base64") {
  // convert from URL first
}

function isBase64Video(video) { return !!video && video.type === "base64"; }

let result;
try {
  result = video.asBase64();
} catch (e) {
  if (!/not base64/.test(e.message)) throw e;
  result = null; // handle URL-backed video
}

When it happens

Trigger: Calling video.asBase64() on a URL-backed Video instance in a project consuming the compiled engine/language_client_typescript/video.js build.

Common situations: Building payloads for model APIs that accept inline base64 media while the app stores videos as URLs; code shared between URL-only and base64-only flows without a representation check.

Understand the failure class

Background: "is not a compatible type" / "cannot merge" errors: when a value's type doesn't match what the library requires — this error's family across 65 libraries.

Related errors

• Video is not base64
• Video is not a URL
• Video is not a URL
• Video input is not yet supported by Anthropic Claude models.
• BAML internal error (AWSBedrock): video file should have bee

AI-assisted analysis of BoundaryML/baml@bd85ce9dee (2026-09-12). Data as JSON: /api/errors/64925cb656ce12cb. Report an issue: GitHub.