Local synthetic media lab

Create a video test file

Generate a short geometric test pattern through this browser's WebCodecs implementation. The workspace checks the exact codec configuration per session and never requests camera, microphone, or upload access.

Recipe v1

Synthetic video recipe

No upload

Output formatDuration (seconds)PatternFrame rateWidthHeightSeed

Capability

Checking this browser session…

Reproducibility: content-equivalent. WebCodecs output bytes can differ by browser, operating system, and hardware encoder.

Generation status

Ready

Fixture-only formats

We link to real catalog samples instead of relabeling unrelated bytes.

3GP samples — Catalog fixture only; this workspace will not put the wrong bytes behind a familiar extension.
AVI samples — Catalog fixture only; this workspace will not put the wrong bytes behind a familiar extension.
FLV samples — Catalog fixture only; this workspace will not put the wrong bytes behind a familiar extension.
MPG samples — Catalog fixture only; this workspace will not put the wrong bytes behind a familiar extension.
OGV samples — Catalog fixture only; this workspace will not put the wrong bytes behind a familiar extension.
WMV samples — Catalog fixture only; this workspace will not put the wrong bytes behind a familiar extension.

Hard limits

1–10 seconds, 24/25/30 fps, up to 1280×720, 70 million pixel-frames, and 64 MiB combined output.

Content reproducibility, not identical encoder bytes

The versioned recipe, dimensions, frame rate, duration, pattern, and seed are reproducible. WebCodecs may choose different software or hardware encoder implementations, so two conforming browsers can emit different bytes for equivalent video. The output hash records what this session actually produced.