Free MP4 test files and sample generator
Compressed video container (H.264/AAC). Common for media playback and upload testing.
What is a .mp4 file?
MP4: Video. MP4 is the default video container of the web and mobile, holding H.264 video in an ISO base media structure. It is what a phone produces and what a browser plays, so it is the format most upload paths will meet first.
Why generate a test MP4 file?
- Test video upload, transcoding and thumbnail extraction.
- Check duration and size limits on a media pipeline.
- Verify playback in a browser player.
What you can put inside a .mp4 file
You get 3 content options for MP4, so the file holds something meaningful rather than random padding: Color bars, Timer / counter, Logo motion. For MP4 these are alternatives, so choose the one that matches what you need to test.
How a .mp4 file is identified
Every .mp4 file begins at offset 4 with 66 74 79 70, "ftyp" at offset 4, the file type box, preceded by its own 4-byte length. That is what a validator inspecting content rather than the file name looks for.
How the size lands on the exact byte
ISO base media files are a tree of boxes, and a `free` box is defined as ignorable, so the padding goes in one.
Negative testing with broken MP4 files
- Invalid. Identifiable, but wrong inside, so it fails during parsing.
- Corrupted. The leading bytes are destroyed, so the
66 74 79 70identifying a .mp4 is gone. Same length as the valid file. - Incomplete. Truncated part-way, so it is genuinely shorter.
- Empty. Chosen under Content rather than File Condition: valid structure, no data.
Which failure to reach for, and what to assert for each, is covered in how to make a corrupted file for testing. For upload limits and type checks see testing file upload validation.
Sample MP4 content
[Binary video], 1080p, H.264, AAC audio.
This shows the shape of the file. Your download is generated fresh at the size you choose, so the values will differ.
How to open and verify the file
Play in any browser or VLC; inspect with `ffprobe file.mp4`.
Media type video/mp4 · extension .mp4 · category Video
Generate a .mp4 file → · questions about sizes, privacy or cost are answered on the site FAQ.
Frequently asked questions about MP4 files
What identifies a .mp4 file?
A .mp4 file begins at offset 4 with the bytes 66 74 79 70, "ftyp" at offset 4, the file type box, preceded by its own 4-byte length. Those bytes are what a content-sniffing validator looks for, and what the Corrupted condition destroys.
How can a .mp4 file be an exact number of bytes?
ISO base media files are a tree of boxes, and a `free` box is defined as ignorable, so the padding goes in one.
What can go inside the MP4 file?
There are 3 content options for .mp4: Color bars, Timer / counter, Logo motion. For MP4 these are alternatives, so pick the one matching what you need to test.
Can I download several broken MP4 files at once?
Yes, select more than one File Condition and you get one ZIP containing a .mp4 per condition, each named after its condition.
Can the MP4 file use UTF-16 or a byte-order mark?
No, and deliberately. A .mp4 file is a container rather than plain text, so rewriting its bytes as UTF-16 would not produce a UTF-16 document. It would produce a broken file. Use a text format such as CSV, JSON or XML for encoding tests.
How do I open or verify the MP4 file?
Play in any browser or VLC; inspect with ffprobe file.mp4.