MKV → WebM
Re-encodes MKV as VP9 + Opus WebM (constant-quality CRF) for royalty-free HTML5 video delivery.
Drag files here or click to upload (multiple files supported)
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How to convert MKV to WebM
- 1Upload your MKV file by dragging, clicking, or pasting.
- 2Adjust quality settings if needed.
- 3Click 'Convert Now' and wait for the conversion to complete.
- 4Download your converted WebM file.
About MKV to WebM conversion
MKV is an open Matroska container released in 2002. It can encapsulate any encoding and multi-track content, and is commonly used for media archiving. WebM is an open subset of Matroska promoted by Google, which only encapsulates VP8/VP9/AV1 video and Vorbis/Opus audio, and is royalty-free. This conversion requires re-encoding to comply with container specifications.
The conversion is based on FFmpeg and uses CRF constant quality mode to control output quality. Only one selected audio track is retained; other audio tracks, subtitle tracks and chapter information are discarded. The output resolution maintains the original aspect ratio to meet common web page requirements, and the file size is smaller than MKV encoded with general settings.
The output can be used for embedded video scenarios in HTML5 web pages. Safari browser requires version 14.1 or above to play VP9-encoded output files normally. Smart TVs and mobile devices can play output files that meet encoding specifications.
MKV vs WebM: technical comparison
| Feature | MKV | WebM |
|---|---|---|
| Released | 2002 | 2010 |
| Developer | Matroska.org |
FAQ about MKV → WebM
Does the quality change after conversion?
Output quality is controlled by the constant CRF parameter. The parameter range complies with FFmpeg standards, and you can adjust it to get the corresponding quality. Conversion requires re-encoding, and quality loss is controllable when parameters are set reasonably.
Will the original MKV subtitles be retained?
Subtitle tracks from the original MKV are not retained after conversion. The WebM container does not natively support embedding external subtitles, and only the selected audio and video streams are retained during conversion.
What is the maximum single file size limit?
The maximum single file size for conversion on this site is 50MB, and only one file can be converted at a time. The duration of the input video must not exceed 10 minutes, files exceeding the limit cannot be processed.
Will my files be stored?
Conversion is completed on the server side. Files are uploaded via HTTPS, and the server immediately deletes both the source file and output file after conversion completes, no storage is performed.