25 KB MKV sample
An MKV file of exactly 25,600 bytes. It is a valid Matroska video file, generated by this site. Compare its checksum and test it with the parser used by your application. Use it wherever you need a 25 KB sample, test or dummy MKV file.
Download
sample-mkv-25kb.mkv
25 KB25,600 bytes
Download 25 KB MKVCreated in your browser in a few seconds, then checked against the SHA-256 checksum. The file is not uploaded anywhere. No sign-up.
- Type
- video/x-matroska
- SHA-256
57a152b35ec70eaff8c79eadad8fcd153838a8194f438f222eb9e17364303ed7- Delivery
- Created in your browser from static generator assets (how it works).
What is in this file
16 frames (0.5 s) of a synthetic test pattern with a frame counter, looping every six seconds, in one H.264 (AVC) video track. The index of key frames comes before the picture data, so a player can seek without reading the whole file. 991 bytes of an EBML Void element bring the file to the exact size.
| Dimensions | 640 × 360 px |
|---|---|
| Duration | 0.5 s |
| Frame rate | 30 fps |
| Video codec | H.264 (AVC), Main profile |
| Audio | No audio track |
| Document type | matroska |
| Clusters | 1, one for each key frame |
| Seek index | Cues element before the first cluster |
First bytes of the file
The first 64 bytes of sample-mkv-25kb.mkv as a hex dump: offset, bytes, then the same bytes as text. The MKV signature is 1A 45 DF A3.
00000000 1a 45 df a3 a3 42 86 81 01 42 f7 81 01 42 f2 81 |.E...B...B...B..|
00000010 04 42 f3 81 08 42 82 88 6d 61 74 72 6f 73 6b 61 |.B...B..matroska|
00000020 42 87 81 04 42 85 81 02 18 53 80 67 01 00 00 00 |B...B....S.g....|
00000030 00 00 63 cc 11 4d 9b 74 b3 4d bb 8e 53 ab 84 15 |..c..M.t.M..S...|Preview
MKV files cannot be shown in a browser. Download the file and open it in an application that reads MKV, such as VLC and mpv.
Where 25 KB matters
A 25,600-byte file: the size of a small web image or a short document. These are the default limits a file of this size is useful for testing:
| System | Limit | Note |
|---|---|---|
| TCP initial congestion window | About 14.6 KB (10 segments) | 25 KB needs at least two flights of packets on a new connection. |
| Base64 encoding | Adds 33 percent | A 25 KB file becomes about 34 KB inside JSON or an email. |
Use this file for
- Checking email size handling
- Checking transcoding and remuxing pipelines
- Verifying type detection between MKV and WebM
Testing notes for MKV
- A file with no Cues element still plays but cannot seek quickly. Recordings that were interrupted, and live captures, are often like this.
- MKV and WebM share a signature. Detection has to read the document type inside the EBML header: "matroska" or "webm".
Technical details
| File name | sample-mkv-25kb.mkv |
|---|---|
| Format | MKV (Matroska video) |
| Extension | .mkv |
| MIME type | video/x-matroska |
| Size | 25,600 bytes (25 KB) |
| Kind | Binary |
| Signature | 1A 45 DF A3 |
| SHA-256 | 57a152b35ec70eaff8c79eadad8fcd153838a8194f438f222eb9e17364303ed7 |
| Created | 2026-10-23 |
| Validation | See the listed size and SHA-256. Small downloads are checked in the browser; verify streamed downloads manually. A hash match does not prove parser compatibility. |
| Preview | Not available for this file; details only |
| Source | Generated in your browser by this site's generator; not copied from elsewhere |
| Licence | Free to use, modify and redistribute (terms) |
| Category | Video |
Check the stated structure and checksum against your application requirements. As with any download, scan the file with your own security tools before opening it. How files are made and checked
Verify your copy
This file is created in your browser, so it has no direct URL for curl or wget. The generator is designed to produce reproducible bytes. After saving, compare the checksum with the SHA-256 value above.
sha256sum sample-mkv-25kb.mkv # Linux
shasum -a 256 sample-mkv-25kb.mkv # macOSOn Windows, run Get-FileHash sample-mkv-25kb.mkv -Algorithm SHA256 in PowerShell. For scripts and pipelines, save the file once and keep your own copy.
Related files
Questions about this file
- Is this file exactly 25 KB?
- Yes. It is 25,600 bytes, which is 25 KB in the binary units that operating systems and server limits use (1 KB = 1,024 bytes).
- What is inside the 25 KB MKV file?
- 16 frames (0.5 s) of a synthetic test pattern with a frame counter, looping every six seconds, in one H.264 (AVC) video track. The index of key frames comes before the picture data, so a player can seek without reading the whole file. 991 bytes of an EBML Void element bring the file to the exact size.
- Which media type should a server send for MKV?
- Most software uses video/x-matroska. RFC 9559 registered video/matroska in 2024, and an allow-list should accept both.