Convert Video

Move a clip between MP4, WebM, MOV and MKV — re-encoding it, or simply rewrapping it when the codecs already fit.

Hybrid processingVideoWorkingNo account needed

What this tool does

Convert Video hands your file to ffmpeg on the processing service and writes it out in one of four containers. A re-encode to MP4 or MOV produces H.264 video and AAC audio, with the index moved to the front of the file so a player can begin before the download has finished; MKV takes the same codecs without that rearrangement; WebM is written as VP9 with Opus. The three quality tiers are constant-quality targets handed to the encoder — high, balanced and small become CRF 20, 26 and 32 — so the size of the result follows from how much detail you asked it to keep, rather than being aimed at in advance. If a specific number of megabytes is the point, Compress Video has the two-pass encode for that and this tool does not.

Copy the streams when possible is the setting worth understanding before you start. When it is ticked, the source video is already H.264 or HEVC, and the target is MP4, MOV or MKV, the picture and sound are remuxed untouched rather than decoded and re-encoded: a MOV to MP4 job then finishes in seconds and no frame is ever recompressed. The conditions are narrower than they look. WebM output never qualifies, so it always re-encodes; a VP9, AV1 or older MPEG-4 source re-encodes even on the way into MP4; and when a copy does happen the quality tier is ignored, because there is no encoding pass for a CRF to apply to. Copying keeps whatever codecs you already had, so an HEVC file rewrapped as MP4 is still HEVC and still needs a player that can decode it, and the sound arrives in its original codec rather than as AAC. A copy also skips the faststart step: the rewrapped MP4 or MOV keeps its index at the end of the file, so a rewrap put straight onto a web server can leave a viewer waiting for the whole download before the first frame appears. Untick the box when changing the codec, not the wrapper, is the actual job.

None of this happens in your browser, and none of it depends on how small the file is: every job travels over an encrypted connection to the machine that runs ffmpeg, is converted there, and then the upload and the file it produced are deleted together at the six-hour mark the job was stamped with. One video goes in each job, up to 200 MB; add several and each is converted separately, one after another. Clips longer than three hours are refused before any work starts, and every job has a ten-minute processing ceiling that a long 4K re-encode can genuinely reach. Input is far more forgiving than output: AVI, WMV, FLV, MPEG and transport streams are all read, but the only video formats it will write are the four in the list.

Three things it deliberately will not do. It never changes the frame size or the frame rate, so a 4K clip converted to MP4 comes out as 4K and Resize Video is where you shrink it; it needs a video track, so an audio-only file is rejected here rather than quietly stripped of its container; and it carries exactly one picture stream and one soundtrack into the result, so a dual-language recording arrives with a single audio track whichever route the job takes. The encoder is also tuned for turnaround rather than for the last few percent of compression: x264 runs at its veryfast preset and VP9 in realtime mode, which means a file from here is somewhat larger than the same quality tier encoded slowly on your own machine. That is a deliberate trade, and it is why a job finishes in minutes instead of hours.

How to use it

  1. Add the file. One video per job, within the 200 MB ceiling. Drop in several and they are converted in turn, each as a separate job with its own result.
  2. Pick the container you want out. MP4 for something that plays almost anywhere, WebM for the open web, MOV for a QuickTime or editing workflow, MKV for a container that will hold nearly anything.
  3. Pick a quality tier. High, balanced or small. This decides how much detail survives the re-encode; whatever file size that produces is the file size you get.
  4. Decide about copying the streams. Leave it ticked for a fast rewrap when the codecs already suit the target. Untick it when you need the picture genuinely re-encoded, for example to turn HEVC into H.264.
  5. Convert, then collect the file. The output keeps the original name with -convert and the new extension appended, so the source and the conversion do not collide in your downloads folder.

Processing & privacy

Hybrid processing. Smaller jobs can run locally; heavier jobs may use secure server processing.

Common use cases

A camera or phone file an editor refuses

MOV and MKV recordings often stall older editing software. Rewrapping them as MP4 usually costs nothing but a container change.

Publishing video on a page

WebM with VP9 and Opus avoids the licensed codecs, at the cost of a full re-encode because stream copying cannot apply to it.

A file that plays silently or not at all

HEVC is the usual culprit on older hardware. Untick stream copying and convert to MP4 to get H.264 that decoders from a decade ago still handle.

Tidying a mixed archive

Footage collected as AVI, WMV, FLV and MPEG can be brought into one video format, so a media library stops needing a different player per decade.

Questions

Does the file leave my computer?
Yes. The work is done by ffmpeg on the processing service and by nothing in the page, so the clip is sent there under TLS, converted on that machine, and erased with everything the job produced six hours after it was accepted.
Does converting lose quality?
It depends on the route. A stream copy re-uses the original frames, so the picture is unchanged. Any real conversion decodes and re-encodes, which is lossy — starting from an already compressed clip, some detail goes each time, so convert from the best copy you have rather than from a previous conversion.
Why did the quality setting appear to do nothing?
Because the job took the stream-copy path. When the source is already H.264 or HEVC and the target is MP4, MOV or MKV, no encoding happens at all, and a constant-quality figure has nothing to attach to. Untick the copy box if you want the tier to take effect.
Can it convert to AVI, WMV or MPEG?
No. Those are read perfectly well as input, but the output list is MP4, WebM, MOV and MKV only. Converting into a legacy container is not offered rather than being quietly approximated.
Does it change the resolution or frame rate?
No. Both are carried through untouched, so the dimensions of the result match the source. Resize Video changes the frame size and Speed Up Video changes the timing.
Why am I asked to solve a small puzzle?
Transcoding occupies a processor core for minutes, so a signed-out job on this tool is asked for a short puzzle first — a sum, the next number in a sequence, a few numbers to type back in order, or which of three words is the animal or the heavier object — to keep automated abuse from taking the queue. A signed-in account is exempt as the service is configured.
Does a second audio track or a subtitle track survive?
Not dependably. One picture stream and one soundtrack are carried into the output, so the commentary track on a dual-language MKV is left behind. Captions only come through when the target container takes the format they are already in: an SRT track reaches an MKV output and is quietly dropped on the way into MP4 or MOV.
Can I convert an audio file here?
No. A file with no video track is turned away with exactly that message, not quietly reshaped into something you did not ask for. Convert Audio is the tool for that, and it writes MP3 and WAV only — the browser it runs in exposes no encoder for AAC, FLAC or OGG.

Related tools