Video Crop & Dimension Adjuster
Video Crop & Dimension Adjuster: Applies canvas clipping rectangle and records cropped video frames via MediaRecorder API.
About this video crop & dimension adjuster
Video Crop & Dimension Adjuster — browser-based utility.
How this tool works
Implements client-side Video Crop operations. Center-crops decoded video frames to the requested aspect ratio, scales to even target dimensions, and records a 30 fps canvas stream with source audio to WebM via MediaRecorder API.
- Video Element Ingestion: Loads local video into a hidden HTML5 video object to extract metadata and decode frames.
- Synchronized Frame Seeking: Seeks across calculated timestamp intervals using asynchronous seeked event promises.
- Canvas Rendering & Scaling: Renders frames to a Canvas 2D context scaled to requested dimensions, which may result in stretching if non-proportional.
- MediaStream & GIF Encoding: Records the running canvas stream to WebM via MediaRecorder or quantizes frames to up to 256 colors for GIF compilation.
Worked example
Scenario: A social video creator crops a 16:9 widescreen video into a 9:16 vertical video for mobile reels.
Sample input:
Processing: Center-crops the decoded source to the 608:1080 target ratio, creates an even canvas at least 2 pixels wide and high, records its 30fps captureStream, includes audio only when video capture exposes audio tracks, and selects supported VP9/Opus, VP8/Opus, or generic WebM.
Illustrative output:
Limits and verification
A file must be decodable by the current browser; codec and container support varies by browser and platform. MediaRecorder outputs WebM, and GIF compilation does not enforce strict file-size limits or maximum durations.
Examples demonstrate an expected workflow; they do not prove every input or every branch of an external specification. Check important results with an independent source before using them for money, security, compliance, safety, or irreversible file changes.
Browser processing boundary
Tool input is processed by code running in the browser and is not intentionally sent to a CZOA processing API. The page can still request ordinary site assets, analytics, or advertising when those services are enabled. Browser extensions and managed-device software remain outside this tool's control.
Relevant references
These references govern or help explain the format, protocol, or calculation used here. Listing a reference does not claim certification or complete implementation of every optional feature.
- W3C MediaStream Recording API (MediaRecorder)
- W3C HTML Living Standard (HTMLMediaElement & Canvas 2D)
Content owner: CZOA Tools · Last reviewed: 2026-09-15 · Review methodology
How to use it
- Enter, paste, or select your input data into the Video Crop & Dimension Adjuster workspace controls.
- Review available parameter fields, units, formats, or options configured for your task.
- Click the action button or observe immediate live calculations rendered in your browser runtime.
- Inspect the resulting output and any diagnostic messages, then copy or download the result if needed.
Frequently asked questions
How does Video Crop & Dimension Adjuster transform the selected file?+
A browser-decodable video is drawn through a centered cover crop: the source is trimmed to the requested width-to-height ratio and rendered as a new WebM. The canvas uses an even width and height of at least 2 pixels, captures at 30 fps, and includes source audio only when video capture exposes audio tracks.
Which inputs and controls does Video Crop & Dimension Adjuster provide?+
The page accepts one video plus width and height fields. It has no crop-position, aspect-ratio preset, time-range, bitrate, codec, frame-rate, or audio control.
What limits apply to Video Crop & Dimension Adjuster output?+
The recorder selects supported VP9/Opus, VP8/Opus, or generic WebM in that order. It re-encodes the full playback; it does not preserve the source container, metadata, timestamps, subtitles, exact audio synchronization, file size, or memory use, and it depends on browser decode, captureStream, and MediaRecorder support.
What does the browser-isolation evidence establish for Video Crop & Dimension Adjuster?+
Recorded browser requests contained no submitted tool payload for the selected file or dimensions. That evidence concerns the tool-value request path; ordinary page assets are separate and it is not a promise about every browser extension or network configuration.