Browser 106

max 300MB

Inspector video/video-crop-time-stretch

Browser Video Crop & Time Stretch

Overview

This browser-based video editor lets you crop to any aspect ratio, trim with a filmstrip timeline, and time-stretch from 0.25x to 4x — all processed locally using FFmpeg compiled to WebAssembly. Unlike cloud editors, your video file never leaves your device: no upload, no account, no waiting for a server. Pitch preservation keeps voices sounding natural at any speed, and you can rotate, flip, fade, or mute before exporting to MP4, WebM, or MOV.

Reframe for Social MediaCrop landscape footage to 9:16 or 1:1 with locked aspect-ratio presets for Instagram Reels, TikTok, or YouTube Shorts without re-uploading anywhere.
Create Slow-Motion ClipsTime-stretch any segment to 0.25x–0.5x with pitch preservation so the audio still sounds natural in your slow-motion highlight reel.
Speed Up TutorialsStretch a long screen recording to 2x–4x speed to produce a condensed walkthrough, then trim the silent gaps from the filmstrip timeline.
Remove Unwanted PortionsUse the trim handles to cut a precise start and end point from a longer video before sharing, keeping only the take you want.
Confidential Footage EditingEdit sensitive HR interviews, medical recordings, or private family videos locally — nothing is transmitted to any server at any point.

Key features

Interactive crop box with aspect-ratio presets
Filmstrip timeline with trim handles and scrubbing
Time-stretch from 0.25x to 4x with pitch control
Rotate, flip, mute, volume and fade
Export to MP4, WebM or MOV with quality presets
100% client-side processing with FFmpeg WebAssembly

Set

Video Tools 06

Neighbours

01 Extract Audio from Video 02 Compress Video 03 HLS Stream Generator 04 Video & Audio Viewer 05 Video Converter 06 Audio Converter

Specification

Command: video.video_crop_time_stretch
Set: Video
Input: MIXED
Output: MIXED
Max file: 300MB
Batch: single file

MP4 QUICKTIME WEBM X-MATROSKA X-MSVIDEO

Runtime

Engine: ffmpeg-wasm 0.12
Threads: — workers
Isolated: —
WebGPU: —
Memory: —

Transport 0 B

The file is opened, worked on and written back inside this tab. No upload step exists in this tool — there is nowhere for the bytes to go.

Keys

Search: ⌘K
Panels: ⌘1 · ⌘2
Full width: F
All keys: ⌘/

How it works

Import Your Video

Drag & drop a video or pick a file. MP4, MOV, WebM and MKV open instantly; AVI, WMV, FLV, MPEG-TS and other formats your browser can't play get a quick preview copy first. Nothing is uploaded — your file stays on your device.

Crop, Trim & Adjust Speed

Drag the crop box, set start/end points on the filmstrip timeline, change the playback speed (with optional pitch preservation), then rotate, fade or mute as needed.

Export & Download

Pick a format and quality and the edit is rendered locally with FFmpeg WebAssembly. Download the finished video when it's ready.

Frequently asked

Are my videos uploaded to a server?

No. All editing and exporting runs entirely in your browser using FFmpeg compiled to WebAssembly. Your video never leaves your device, which keeps it completely private.

Which video formats can I import and export?

You can import MP4, MOV, WebM, MKV, AVI, WMV, FLV, MPEG-TS, MPG, OGV, MXF and most other video formats. When your browser can't play a format itself, the tool makes a preview copy (a quick repackage, or a slower conversion for older codecs) — the export always uses your original file. Exports are available as MP4 (recommended, fastest and most compatible), WebM and MOV.

How does time-stretching work?

Pick a speed from 0.25x up to 4x, or type a target duration and we calculate the speed for you. By default audio pitch is preserved so voices still sound natural; you can also let the pitch change with the speed for a classic fast/slow effect.

Can I crop to a specific aspect ratio?

Yes. Use the freeform crop box or lock it to presets like 1:1, 4:5, 9:16, 16:9 and 21:9. The output resolution updates live as you resize.

Is there a file size limit?

Because everything runs in your browser's memory, very large files can be slow or run out of memory. We recommend videos up to about 300MB for a smooth experience.

Why is exporting to WebM slower than MP4?

WebM uses the VP8 encoder, which is slower in WebAssembly than the H.264 encoder used for MP4. For the fastest exports with the widest device compatibility, choose MP4.

Keys

Search: ⌘K
Panels: ⌘1 · ⌘2
Full width: F
All keys: ⌘/

Related · Video Tools