Intentionally Corrupt — MP4 Header Fragment Only
An intentionally corrupt MP4 cut off half way through its `moov` box: the `ftyp` header survives, the index does not, and there is no media data at all. Not a valid file by design. Just enough for content sniffing to succeed and everything after that to fail. A `file`-style magic check reports ISO Media, a MIME sniffer says video/mp4, and then the box walk runs off the end of the buffer part way through the index. Useful for testing the gap between format detection and format validation — and for the upload path, where the two are frequently the same check. Distinct from the two other truncations in this group: the mid-mdat file has a complete index and missing media, this one has a broken index and no media, and a length-based cut deep enough to matter is the only way to tell those code paths apart.
mp4
video/mp4
- Integrity
- intentionally corrupt
- Damage
- cut half way through the moov box
- Ftyp Intact
- true
- Moov Present
- truncated — header only, contents incomplete
- Media Data Present
- false
- Original Bytes
- 13016
Binary mp4: no in-browser preview. Download it above to open in a compatible application.
Specifications
- Integrity
- intentionally corrupt
- Damage
- cut half way through the moov box
- Ftyp Intact
- true
- Moov Present
- truncated — header only, contents incomplete
- Media Data Present
- false
- Original Bytes
- 13016
- Expected Behaviour
- magic bytes detect as MP4; the index never finishes parsing
Testing contract
Expected to fail- Scenario
- Run content sniffing over the first bytes, then attempt a full box walk.
- Expected result
- Sniffing succeeds - the magic bytes identify ISO Media and a MIME sniffer returns video/mp4 - and the box walk then runs off the end of the buffer inside the moov box. There is no media data at all in the 869 bytes. The fixture's value is the gap it opens between format detection and format validation, which upload paths routinely treat as the same check.
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 — MP4 Header Fragment Only” 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: cut half way through the moov box. 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-header-only.mp4"></video>Related files
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Generated by generation/video_accessibility.py. Free for any use, no attribution required, license.