Video Eraser API for Video Subtitle and Watermark Removal

What the 550W developer API actually supports

The 550W developer API lets a backend submit authorized video subtitle/text or watermark-removal jobs using a selected rectangle, plus image watermark-removal jobs. API access does not grant rights to source media, and completed results still need review.

Video subtitle and watermark removal

For video, submit MP4 or MOV footage through /open/uploadVideo or provide a public videoUrl to /open/submitTask. The request includes video dimensions, duration, and the rectangle to repair. Video jobs run asynchronously and can be checked through /open/taskDetail or /open/taskList.

Image watermark removal

For images, /open/removeImageWatermark accepts JPG, PNG, BMP, WebP, AVIF, TIFF, or SVG files up to 50 MB. It can wait for a result or return a processing task for later lookup. The Eraser developer API does not expose video-link watermark downloading, so integrations should not promise that capability.

Use the API for authorized video subtitle/text cleanup and image watermark removal; keep unsupported video-link watermark workflows out of your product promise.

A production-ready request flow

Every request is authenticated with userNo and apiKey. Keep both values on your server: placing an API key in browser or mobile client code makes it recoverable by users and extensions. A video may be uploaded first or supplied as a publicly reachable HTTP(S) URL.

Authenticate and upload

Submit /open/submitTask with width, height, duration, and x1, y1, x2, y2. In Standard mode (mode=normal, the default), the selected rectangle is processed. In Protect mode (mode=protect), the selected rectangle is kept and the area outside it is processed; Protect is not a higher-quality mode. Set removeAudio only if audio should be stripped before processing.

Submit an idempotent job

Send an Idempotency-Key of no more than 128 characters for retry-safe creation. If a connection drops after submission, retry with the same key instead of creating a second billable job. Store the returned taskId beside your own asset ID.

Receive and verify the result

For asynchronous delivery, provide a public HTTP(S) callbackUrl. The webhook fires when the task reaches a final state. Your handler should acknowledge quickly, verify the task again through /open/taskDetail, and treat repeated webhook delivery as normal. Polling remains useful as a recovery path when a callback is delayed.

Server-side credentials, idempotency, durable task IDs, and webhook verification make retries safe and observable.

Input limits and quality controls

API input rules can differ from the browser video workflow. Check the current developer documentation, then validate format, duration, dimensions, bit depth, and HDR status before submission so unsupported media does not enter the paid workflow.

Validate before spending credits

Quality depends on what moves behind the subtitle or text. Flat walls, sky, and slowly changing scenery are usually easier than hands, hair, patterned clothing, reflections, or fast camera movement. Build a review queue for edge cases and compare the entire timeline, not only a thumbnail.

Review difficult footage

Image jobs support common web and design formats and cost a fixed number of credits per successful task according to the current API page. Preserve the source file and save the result as a derivative; watermark removal does not create copyright or commercial-use permission.

Reject unsupported inputs early and require human review whenever the repair area crosses important moving detail.

Billing, failures, and retry policy

Video subtitle removal is billed by duration and resolution. The current schedule is 1.3 credits per second at 720p or below and 1.6 credits per second above 720p up to 1080p. A 30-second 1280×720 video is therefore about 39 credits, while a 30-second 1920×1080 video is about 48 credits. Query /open/queryCredits before accepting a large batch.

Estimate cost before submission

Successful responses include code and message; task responses additionally expose status and, when complete, resultUrl. Failed tasks can include failCode, failReason, and refundStatus. Retry temporary transport or internal failures with exponential backoff, but do not blindly retry invalid parameters, unsupported media, suspended accounts, or insufficient credit errors.

Handle stable failure fields

Record submission latency, completion latency, failure rate, review rejection rate, and cost per approved asset. These metrics reveal whether automation is improving the workflow instead of merely moving manual work downstream.

A useful integration measures approved output and effective cost, not just successful HTTP responses.

Launch the integration in four steps

First, generate an API key from the localized 550W developer page and submit one representative video. Second, implement task lookup and display waiting, processing, success, and failed states in your own product. Third, add idempotency and a webhook with polling recovery. Finally, run a controlled batch and review every output before increasing concurrency.

Pilot before scaling

Use separate development and production controls, rotate exposed credentials, restrict access to source media, and keep a deletion policy for results. Teams with clear acceptance criteria can then connect the API to a DAM, CMS, localization queue, or creator upload workflow without sacrificing editorial review.