MKV to PNG converter

PNG is the output you choose when the still has to survive further work. It adds no lossy generation of its own — but it also cannot repair what the video encoder already threw away. This page is written as a short working session around one frame at 1.5 seconds.

Only one still frame is kept; audio, motion and the rest of the clip are discarded.

Drop files here or Choose files MKV, up to 60 MB

Add a file to start.

Processed on your device. Files aren’t sent anywhere.

No sign-up. Nothing to install.

The generation question

Every encoding is a generation. A recording is already one lossy generation of the scene it captured. Exporting that frame as JPG adds a second. Exporting it as PNG adds none.

Illustrative: Ana has a four-second MKV capture of a UI bug and needs the frame at 1.5 s placed beside a screenshot of the fixed build. She will overlay annotations and compare pixel differences, so a second lossy encoding would blur exactly the edges she is measuring. PNG is the choice that keeps the comparison honest.

PNG does not improve the frame. It stops the frame from getting worse.
The rule this route exists for

A working session at 1.5 seconds

Ana opens the MKV here, sets the timestamp slider to 1.5, and converts. There is nothing else to tune: this route has no quality control, because PNG is not a lossy format.

Load the MKV; the first run pulls about 32 MB of WASM for the local worker
Set the timestamp — half-second steps from 0 to 600 seconds, default 1 second
Convert and download the PNG
Open it at the size you will compare at, then annotate or diff against your reference

What PNG keeps and what it cannot bring back

PNG stores the decoded pixels exactly, so the frame you get is the frame the video held. Dimensions are unchanged, and the file is safe to re-save, crop and annotate without further degradation.

What it cannot do is restore detail the video encoder discarded. Block artefacts, banding in gradients and mushy text in a low-bitrate recording are part of the frame. PNG preserves that damage faithfully; only a better source recording can supply better pixels.

Kept: exact pixel values of the decoded frame, unchanged dimensions
Kept: editability — annotations and re-saves add no further loss
Not kept: audio, motion, and every frame other than the selected one
Not recoverable: detail the video encoder already discarded

There is no quality dial here

The JPG sibling route exposes quality 40–100. This one does not, and that is deliberate: a lossless encoder has no quality knob to offer. If you want a smaller file for delivery rather than a still you will keep editing, use MKV to JPG and accept one extra generation.

PNG files are usually larger than JPG files for photographic frames
For flat-colour UI captures PNG often wins on both size and sharpness
No setting on this page is a quality percentage or a lossless WebP mode

Questions

Is my video sent to a server?

No. Decoding runs in your browser tab through a single-threaded FFmpeg worker whose core and WASM are served from this same origin. The worker is terminated after each conversion and whenever you cancel.

Why is the PNG bigger than the JPG?

PNG stores every pixel of the decoded frame, which for photographic frames is typically more data than JPEG's block encoding. For flat-colour UI captures PNG can be both smaller and sharper.

Can this clean up a heavily compressed recording?

No. The frame inherits whatever compression the video already applied. PNG stops further loss; it does not undo existing loss.

What happens if I set a timestamp past the end of the clip?

The request is clamped near the end and you get the last playable frame, rather than an error. The slider itself runs 0–600 seconds in 0.5-second steps.

When PNG is the wrong answer

A single still cannot carry a sequence, and a lossless still is not always the file someone wants to receive. Match the output to the destination.

Destination	Better route here
A thumbnail in a card or a mail attachment	MKV to JPG, quality 70–90
A frame you will annotate, crop or diff	MKV to PNG, this page
A sequence a reviewer reads in a document	MKV to PDF contact sheet
A frame past roughly 2 megapixels or a file over 60 MiB	None of these routes — the source is refused

The cost of the first run

Decoding happens in your browser through a single-threaded FFmpeg worker served from this same origin, so the first conversion loads about 32 MB of WASM before any frame is decoded. Later runs in the same tab are quicker. The worker is terminated after each conversion and whenever you cancel, which keeps memory from accumulating between jobs. The page must be served over HTTP(S); there is no cloud step and nothing is uploaded.

Coverage is bounded by what the vendored FFmpeg build can decode. This route is beta and is tested against an MJPEG-in-MKV fixture, so other codecs may fail rather than hand you a wrong frame.

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