Canvas Animation to Video Converter

Recording an HTML5 Canvas animation to a distributable video file has historically required server-side FFmpeg pipelines or frame-by-frame PNG export followed by manual stitching. Both approaches introduce latency, storage overhead, and deployment complexity. This tool eliminates that dependency entirely by leveraging the browser-native captureStream(fps) method on the <canvas> element, piping the resulting MediaStream into a MediaRecorder instance configured for VP8/VP9 WebM encoding. The output is a standards-compliant video file generated with zero server round-trips. Recording fidelity depends on the client GPU and the complexity of the draw loop. Frame drops occur when the compositor cannot maintain the requested fps under heavy fill-rate pressure. This tool approximates constant-framerate output, but the WebM container uses variable frame timing internally. For production pipelines requiring H.264/MP4, the exported WebM can be transcoded offline via FFmpeg.

The canvas stream capture pipeline follows a direct data flow from the rendering context to an encoded video container:

Estimated output file size can be approximated by:

where S is file size in bits, bitrate is the encoder output rate in bps, and t is duration in seconds. For VP8 at default quality on a 720p canvas:

Frame timing within the animation loop uses delta-time normalization to decouple rendering speed from monitor refresh rate:

where δ is the elapsed time in seconds, used to scale all position updates. This ensures consistent animation speed whether the display runs at 60 Hz or 144 Hz.