Intentionally Corrupt — Zero-Byte MP4
An intentionally corrupt MP4 containing nothing at all — zero bytes, with a `.mp4` extension. Not a valid file by design. The degenerate case, and one that reaches production more often than any other: a failed upload, a `touch`ed placeholder, a copy that never started. It is worth having because so much code divides by duration, reads the first N bytes without checking N, or reports 'unsupported format' for a file that has no format to support. Note that content sniffing cannot help here — there are no magic bytes — so anything that must classify this file has only the extension to go on.
mp4
video/mp4
- Integrity
- intentionally corrupt
- Damage
- no content at all
- Bytes
- 0
- Expected Behaviour
- no magic bytes; sniffing must fall back to extension
Binary mp4: no in-browser preview. Download it above to open in a compatible application.
Specifications
- Integrity
- intentionally corrupt
- Damage
- no content at all
- Bytes
- 0
- Expected Behaviour
- no magic bytes; sniffing must fall back to extension
Testing contract
Expected to fail- Scenario
- Classify the file, then read its duration and first N bytes.
- Expected result
- The file is exactly 0 bytes, so there are no magic bytes and content sniffing cannot classify it - only the .mp4 extension is available. Every read returns end-of-file immediately, and any code that divides by duration, or reads a fixed-size header without checking how much it got, fails here rather than reporting an unsupported format.
What is a .mp4 file?
MP4 (MPEG-4 Part 14) is the dominant container for digital video, holding video, audio, subtitle, and metadata tracks in a tree of typed boxes. `ftyp` declares the brand, `moov` carries the sample tables that make seeking possible, and `mdat` holds the media; when an encoder writes `moov` last, playback cannot begin until the file has fully downloaded, which a faststart remux fixes. It derives from Apple's QuickTime format, generalized by ISO into the ISOBMFF base that MOV, 3GP, and HEIF share.
How to use this file
Use an example MP4 to test box parsing and track detection, seeking, range-request streaming, and transcode or thumbnail pipelines: verifying that a file with a trailing `moov` box is still handled, and that codec support is checked per track rather than inferred from the extension.
How to use this file for testing
“Intentionally Corrupt — Zero-Byte MP4” is a deterministic Novus Examples fixture for Error handling, Video QA, Video codecs. Deliberately corrupt and invalid files, clearly labelled, for testing how your tool fails.
Documented properties for this file: damage: no content at all. 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="mp4-zero-bytes.mp4"></video>Related files
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- webmAlpha Channel — VP9 in WebMVideo with a real per-pixel alpha channel: VP9 yuva420p in WebM, the one alpha path browsers decode natively. Composite it over a page background and the transparency is genuine, not a chroma key. Roughly 90% of each frame is fully transparent. Two traps this file exists to expose. First, auto-alt-ref must be disabled at encode time or libvpx silently drops the alpha plane, producing a valid file with no transparency and no error. Second, WebM stores VP9 alpha in BlockAdditional and signals it with AlphaMode=1, so FFmpeg's NATIVE vp9 decoder reports pix_fmt yuv420p and decodes fully opaque — you must force `-c:v libvpx-vp9` to see the alpha at all. Probing this file with default settings and concluding it has no alpha is the expected mistake.
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- mp4Bitstream — All-Intra (Every Frame a Keyframe)Every frame is an I-frame, so any frame is an independent cut point. Much larger, and the shape editing and frame-accurate seeking want. Same picture and same codec as every other clip in this group — only the GOP and frame-type structure differ, so the effect on size and seekability is directly attributable.
Generated by generation/video_accessibility.py. Free for any use, no attribution required, license.