Video Converter & Compressor
Convert and compress video in your browser — MP4, MOV, WebM, MKV; H.264, HEVC, AV1, VP9; target size, resolution, frame rate, trim, crop, rotate
How it works
Drop video or audio files — MP4, MOV, MKV, WebM, MPEG-TS, MP3, WAV, FLAC, Ogg and whatever else the browser can demux — and each is probed for its container, codecs, size, frame rate, duration and bitrate. Pick the output: MP4, MOV, WebM or MKV with H.264, HEVC, AV1, VP9 or VP8 for the picture (codecs this browser cannot encode are marked) and AAC, Opus, MP3, FLAC or PCM for the sound, or an audio-only M4A, MP3, Ogg, FLAC or WAV to extract the sound. Set the rate as a quality level, an explicit bitrate, or a target file size in MB — the bitrate is worked out from the duration and the sound's share, and the estimated size and the ratio to the source are shown before you start. Change the size (presets or a custom width and height, letterboxed, cropped to fill or stretched), the frame rate, rotate, crop a rectangle, set the keyframe interval, prefer the hardware or software encoder, drop the picture or the sound, re-sample or re-mix the sound, raise or lower its gain, peak-normalise it, trim a start and end, keep, strip or set tags. Presets cover the common cases — a web MP4, the smallest file, a messaging-sized clip, audio only, a lossless remux. A stream whose codec already fits the container is copied packet by packet when the codec is left to keep, the rate is a quality level and nothing about the picture changes, so remuxing or trimming is lossless and takes seconds; everything else is decoded and encoded again with the browser's WebCodecs. Batches run file after file with progress and speed; results play in the page and download one by one or together as a ZIP, or — with the File System Access API — stream straight into a folder you pick, so multi-gigabyte files never sit in memory. The settings travel in the share link; the files never leave your device.
Questions
How do I make a video smaller?
Pick Target size and type the MB you want per file: the picture's bitrate is worked out from the duration after the sound's share, and the estimate shows the result before you convert. For the smallest files at a given quality use AV1 (where this browser encodes it) or HEVC instead of H.264, lower the size to 1080p or 720p, and drop the frame rate to 30 if the source is 60. A quality level or an explicit bitrate works the same way.
Which formats and codecs are supported?
Input: anything the browser demuxes — MP4, MOV, M4V, MKV, WebM, MPEG-TS, plus MP3, WAV, FLAC, Ogg and AAC audio. Output containers: MP4, MOV, WebM, MKV, and audio-only M4A, MP3, Ogg, FLAC, WAV. Picture codecs: H.264, HEVC, AV1, VP9, VP8 as this browser's encoders allow (Chrome and Edge encode all of them on most machines; Safari and Firefox fewer). Sound: AAC, Opus, MP3 (through a WebAssembly encoder), FLAC, PCM.
Does converting lose quality?
Only when a stream is re-encoded. With the codec left to keep and the rate on a quality level, a stream that fits the container is copied as it is — a remux or a trim loses nothing and takes seconds. Scaling, a new frame rate, rotation, crop, an explicit codec, a bitrate or a target size re-encode the picture, which costs some quality; choose High or Very high, or a generous bitrate, when that matters.
Are my files uploaded?
No. Demuxing, decoding, encoding and muxing all run in your browser with WebCodecs. Large files work; with a folder as the destination the output streams straight to disk, so even multi-gigabyte conversions need no memory to speak of.
Why is a codec greyed out?
The encoders come from the browser and the machine. HEVC and AV1 encoding usually need hardware support or a recent Chrome; Safari and Firefox lack several WebCodecs encoders. Pick another codec, or convert in Chrome or Edge.
How is this different from the Audio Converter?
The Audio Converter is the audio-only page with the full set of audio options. This tool handles the picture as well — codecs, size, frame rate, rotation, crop, target size — and converts batches of video files; it extracts audio too.