AnyTool
Your files never leave your device. All processing happens locally in your browser.

How do I add a blurred background to fit a video into a vertical frame?

Open AnyTool's Video Background Blur, drop in a clip, and pick a target aspect ratio (9:16, 1:1, 4:5 or 16:9). It fits the video into that frame and fills the empty bars with a scaled, blurred copy of the video itself — the popular look for turning landscape clips into vertical TikTok, Reels or Shorts — with adjustable blur strength, plus a full-frame blur mode. It runs with a self-hosted ffmpeg engine in your browser — the video is never uploaded, the engine is bundled (no CDN), and there is no signup, watermark or size cap. Note: this is blurred-background reframing, not AI subject cutout.

  • Reframe to 9:16, 1:1, 4:5 or 16:9 with blurred bars (no black bars)
  • Fills empty space with a scaled, blurred copy of the video
  • Adjustable blur strength; also a full-frame blur mode
  • Self-hosted engine — no CDN, no upload, no watermark

What is

Blurred-background reframing

Blurred-background reframing fits a video into a different aspect ratio without cropping the subject by filling the leftover space with a scaled, blurred copy of the same video instead of plain black bars. It is commonly used to turn landscape clips into vertical 9:16 video for TikTok, Reels and Shorts; a full-frame blur mode blurs the whole picture. This is not AI subject cutout. Client-side processing runs in the browser, so the video is never uploaded.

Video Tools

Related terms

aspect ratioreframevertical videoTikTokffmpeg

How to Add a Blurred Background to a Video

Reframe a video into a new aspect ratio with blurred bars in your browser.

40 secWeb browser
  1. 1

    Add a video

    Drop in a clip — it stays on your device.

  2. 2

    Pick a frame

    Choose 9:16, 1:1, 4:5 or 16:9 and set the blur strength (or full-frame blur).

  3. 3

    Export

    Render the reframed video and download an MP4 — nothing is uploaded.

Result: A reframed video with a blurred background

Frequently Asked Questions

Pick a 9:16 target and it fills the empty space with a scaled, blurred copy of your video instead of black bars.

It also supports 1:1, 4:5 and 16:9 targets, with adjustable blur strength for the background.

No — it is blurred-background reframing, not AI subject cutout.

The background bars are simply a scaled, blurred copy of the same video; a full-frame blur mode is also available.

No — the reframing runs entirely in your browser with a self-hosted engine.

The video never leaves your device and there is no size cap, signup or watermark.

Detailed Explanation

Methodology

How the Video Background Blur Tool Works

AnyTool blurs video backgrounds entirely in the browser using a self-hosted single-threaded ffmpeg.wasm engine — the core (ffmpeg-core.js + the 32 MB wasm) is bundled from npm and served as a same-origin asset, so nothing is fetched from a CDN. In the reframe mode the filtergraph splits the source into two copies: one is scaled to COVER the target aspect ratio and blurred with the gblur filter to fill the frame as the background, while the other is scaled to FIT and overlaid centered on top — giving the popular blurred-bars look that fits any clip into a new aspect (for example portrait into landscape). A simpler full-frame mode just applies gblur to the whole video. The result is re-encoded to H.264/AAC and read back as an MP4 blob. This is a deterministic filter effect, not ML person segmentation. Single-threaded is deliberate: the multi-threaded core needs SharedArrayBuffer + cross-origin isolation (COOP/COEP), which would block cross-origin ad iframes.

  • Runs client-side — the video is never uploaded
  • Self-hosted ffmpeg core (bundled) — no CDN
  • Reframe: source split — COVER+gblur background, FIT overlay
  • Centered overlay gives the blurred-bars reframing look
  • Full-frame gblur mode also available
  • Filter effect, not ML segmentation; H.264/AAC MP4
  • No backend, no signup, no size cap
Privacy & Security

Privacy vs Upload-based Blur Tools

Most online background-blur tools upload your video to a server and cap the free tier or add a watermark. AnyTool blurs and reframes locally with a bundled engine, so the video never leaves your browser, there is no size cap or watermark and no signup, and it works offline after the first load.

Video background blur: AnyTool vs typical tools
CapabilityAnyToolTypical tools
Data handlingIn your browserOften uploaded
Reframe modeBlurred-bars (cover+fit)Rare
Blur enginegblur filterVaries
Full-frame blurYesVaries
CostFree, no signupFree/limited

AnyTool is a privacy-first client-side blur tool — processing runs locally and nothing is uploaded.