Video Converter

How to use

1. Drop the clip onto the Video area, or use Choose file.
2. Read the file card: it names the container, the length, the frame size and the codecs inside.
3. Pick a target under Convert to. Only the containers the clip isn't already in are listed, each tagged instant or re-encode.
4. Check the strip under the targets. It says whether the move is a repackage or a re-encode and to which codec, before you commit.
5. Press Convert and keep the tab open while the run row counts through the clip. Cancel stops it and keeps the original loaded.
6. Play the converted take, switch back to the original if you want to compare, then press Download.

About this tool

Most “this video won't play” problems are container problems. The footage is fine; the wrapper around it is one the phone, the editor or the website refuses to open. Drop the clip in and its card names what is inside, container, length, size and both codecs, and the containers you are not already in appear as targets. Each one says instant or re-encode before you press anything.

Instant means the container can hold the tracks you already have, so the packets are copied across with no quality lost and the job takes moments. Re-encode means the target expects a different codec and every frame is decoded and written again by WebCodecs on your device, which takes real time on a long clip. Where this browser has no encoder for what a container needs, that target is switched off with the reason next to it instead of failing halfway.

The converted clip plays in the same window as the original, with a Take switch between the two. Check that the sound came along before saving. The file keeps your clip's name with the new extension, and the container you picked is remembered for the next visit.

One holiday clip, three very different targets

A four-second phone clip saved as an MP4 with VP9 picture and Opus sound reads as exactly that on its file card: MP4 · 0:04 · 640 × 360 · VP9 + Opus. The targets are the three containers it is not already in. MKV and WebM both say instant, because both carry VP9 and Opus as they are, and pressing Convert on MKV hands back holiday-clip.mkv with the same frames in a new wrapper.

MOV says re-encode. QuickTime files expect H.264 or HEVC, so every frame goes back through the encoder on its way to H.264 and the sound becomes AAC. The strip says Re-encode to H.264 before you press anything, and the run row counts through the clip while it works.

Rough edges

What this tool leaves out

• Instant depends on what each container conventionally holds. MP4 takes H.264, HEVC, VP9 and AV1; MOV takes H.264, HEVC and ProRes; WebM takes VP8, VP9 and AV1; MKV takes all of them. A VP8 clip going to MP4 is therefore re-encoded, even though some players would cope with it as it is.

What a browser cannot do

• Four containers come out: MP4, MOV, MKV and WebM. AVI, WMV and FLV cannot be written from a browser page, so they are not offered.
• The whole output is built in memory before it is handed over. A phone converting a long 4K recording can run out of room late in the job.