WebM — VP9 Short Clip
Short VP9 WebM SAMPLE companion for container conversion tests.
Browser-playable test video · 2 seconds
Specifications
- Resolution
- 480x270
- Fps
- 24
- Codec
- VP9
- Container
- WebM
- Duration
- 2.00s
Testing contract
Expected to pass- Scenario
- Decode the clip and confirm its geometry and the event the fixture is named for.
- Expected result
- 480x270 at 24 fps, 2.00s, VP9 in WebM. A companion clip for the Wave G subtitle group, carrying no caption track of its own.
What is a .webm file?
WebM is a deliberately narrow profile of Matroska, restricted to codecs anyone may implement royalty-free. It keeps Matroska's EBML structure but permits only VP8, VP9, or AV1 video with Vorbis or Opus audio, which is what made it the open counterpart to MP4 in an HTML5 `<video>` element. Google announced it at I/O in 2010 alongside the newly open-sourced VP8 and added VP9 and Opus in 2013. That restriction is also its limit: a WebM cannot carry H.264 or AAC at all.
How to use this file
Use an example WebM to test HTML5 `<video>` playback, EBML demuxing, and VP8/VP9 decoding, checking that a converter turning an MP4 into WebM re-encodes rather than attempting a stream copy, since neither H.264 nor AAC has any place in the container.
How to use this file for testing
“WebM — VP9 Short Clip” is a deterministic Novus Examples fixture for Conversion testing. The same content exported across many formats and linked as a group, so you can convert one and diff against the expected twin.
Documented properties for this file: 2.00s · 24 fps. Compare results against paired or grouped companions on this page when present (clean↔damaged, searchable↔scanned, or format twins) so scores stay reproducible across runs.
Download the file once, keep the path stable in CI or local scripts, and treat the spec table as the contract: dimensions, seeds, field lists, and roles are intentional. Corrupt or invalid samples are labelled as such, expect parsers to fail loudly rather than silently accept them.
Media fixtures are short and synthetic by design. Prefer waveform or transcript ground truth in the same group when measuring ASR, trim, upscale, or sync tools; do not assume broadcast-quality masters.
Code examples
<video controls preload="metadata" width="640" src="soft-sub.webm"></video>Related files
- mp4MP4 — Hard-Burned Caption (EN)Hard-burned EN SAMPLE caption for OCR language tests.
- mp4MP4 — Hard-Burned Caption (ES)Hard-burned ES SAMPLE caption for OCR language tests.
- 3gp3GP — Mobile H.264 ClipThe clip as 3GP — the 3GPP mobile container from the feature-phone era. For testing 3GP demuxing and conversion.
- mp460 fps Clip (MP4)A 60 frames-per-second clip with a smoothly sweeping marker — double the usual frame rate. A fixture for testing high-frame-rate playback, frame-rate detection, and fps conversion (60→30 decimation).
- mp4A/V Sync — Beep + Flash (MP4, with audio)A five-second clip that flashes white and plays a 1 kHz beep on every whole second — the first clip in the library WITH an audio track. A direct fixture for measuring and correcting audio/video sync (lip-sync) offset.
- webmAlpha Channel — Opaque VP9 TwinThe same codec and container with NO alpha plane, as the control for the alpha clip in this group. Useful for checking that alpha detection reads the pixel format rather than assuming every WebM is transparent — and for confirming a compositing bug is in the alpha handling rather than in the player.
Generated by generation/video_wave_g.py. Free for any use, no attribution required, license.