Cut a clip down to the part you need. Drag the in and out handles on the thumbnail strip, or play to a frame and set the start or end at the playhead, then choose how the cut is made.
Exact frame vs key frame
Compressed video stores a full picture only every so often. These are key frames, and the frames between them are stored as changes from the frames before. That is why there are two ways to cut.
- Exact frame decodes the kept range, starts on the frame you picked, and re-encodes it. The cut lands where you set it, and the export takes about as long as the clip plays.
- Key frame copies the compressed packets from the key frame at or before your start to the key frame at or after your end. Nothing is decoded or re-encoded, so a long clip finishes in seconds and the picture is bit for bit the source. The cost is precision: each cut moves outward to the nearest key frame.
Use key frame when you are cutting a long recording down to a section and a second of slack at each end is fine. Use exact frame when the cut has to land on a specific moment, such as the start of a sentence.
Setting the range
The dimmed part of the timeline is what gets removed. Press near a handle to drag it; press anywhere else to move the playhead. Playback loops inside the range, so what you hear is what you keep. The Start and End fields take values to a hundredth of a second for cuts you have measured elsewhere.
The range is kept in the page address, so a shared link opens with the same cut points.
Audio
The soundtrack is trimmed to the same range. A key frame cut copies the audio packets from the same start point, so sound and picture stay aligned. An exact cut decodes the audio and cuts it on the sample. Remove audio drops the track entirely.
Output
The trimmed file keeps the source container: MP4 stays MP4, MOV stays MOV, WebM stays WebM. The result under the controls reports the length, the container and codec, and whether the video was copied or encoded.
Large files
The source is read from disk as the export runs, and the output streams to browser storage, so a file larger than memory still works. Trimming a two hour recording with a key frame cut reads only the packets inside the range.