Free video editing tools

Which edits need re-encoding

Every edit on this page falls into one of two groups. Some can be made by copying the compressed video and audio that are already in your file into a new file, without decoding a single frame. Others have to decode the picture back into raw frames, change those frames, and compress them again from scratch. The first group is fast and loses nothing; the second is slower and, because almost every video codec is lossy, costs a small amount of quality each time it runs.

Copying is possible when the edit does not need to change what is inside any frame. Removing the sound, cutting at keyframes, splitting, repeating a clip and joining clips with matching settings all rearrange or drop whole pieces of the file, so they can copy. Rotation can too: for a file whose codecs MP4 can hold, the turn is written into the file as orientation metadata rather than drawn into the pixels. Raising the volume sits in between: the sound has to be decoded and re-encoded to change its level, but the picture beside it is copied untouched when its codec allows.

Cropping, flipping, changing speed, reversing and a frame-exact trim all change the frames themselves or their timing, so they always re-encode. Here that means H.264 video with AAC sound in an MP4 file, or VP9 and Opus in a WebM file when your browser cannot make MP4.

Copying also depends on the codecs inside your file, not only on the edit. The fast paths work when the video is H.264 or HEVC and any sound is AAC or MP3, the pairings MP4 was built around; the splitter, the looper and the merger can also copy VP8, VP9 or AV1 video with Opus or Vorbis sound into WebM. Anything else is re-encoded, which needs your browser to decode the video first. A file it cannot decode can only go through the copy paths above, where its codecs allow one; a tool that would have to re-encode it says so before you press the button. You never have to guess which path applies: after you choose a file, each tool that writes a video shows a plan line saying whether it will copy or re-encode, before you press the button.

Trimming: fast cuts and precise cuts

Most video is stored as occasional complete pictures, called keyframes, with the frames in between recorded only as changes from the frames around them. That is what makes video files small, and it is also why a cut cannot always land exactly where you want it without re-encoding: a frame in the middle of a run cannot be shown without the keyframe it depends on.

The trimmer's Fast mode copies the video and so has to start from a keyframe. It begins the copy at the keyframe at or before your start time and marks the frames before the cut as a hidden lead-in, using a feature of MP4 called an edit list. The cut itself falls where the frame on screen at your start time begins, so Chrome starts playback on that frame, up to one frame before the time you entered; a player that ignores edit lists shows the lead-in instead, so in some players the clip can start early by as much as the gap between two keyframes. The end can also run a fraction of a second past the time you set. In exchange, the cut takes moments and the picture is untouched.

Precise mode re-encodes, so both cuts land on the exact frame you chose, at the cost of a slower run and a small loss of quality. Fast mode is only offered as a copy when your file's codecs can go into MP4 as they are; for any other file the trimmer re-encodes whichever mode you pick, provided your browser can decode it, and then the cuts are exact anyway.

Times can be typed as plain seconds, such as 12.5, or as minutes and seconds, such as 1:05. A trim must keep at least a tenth of a second, and the end time must fall inside the clip.

Cropping and rotating without losing quality

Rotation is the one change to the picture that can usually skip re-encoding. For a file with H.264 or HEVC video and AAC or MP3 sound, the rotate tool writes the turn into the MP4 file as orientation metadata and copies the streams unchanged, so the result is quick and identical in quality to the original. A player that reads that metadata turns the picture as it shows it. The turn is added to any rotation the file already carries, which matters for phone footage: a clip that already plays upright is turned a further 90, 180 or 270 degrees clockwise. Files in other codecs are re-encoded, with the rotation applied, provided your browser can decode them.

Flipping is different. A mirror image can also be described as metadata, but a player that does not read it would show the video unflipped, so the flip tool always draws the flip into the frames themselves and re-encodes, which makes the result look the same everywhere.

Cropping always re-encodes, because it changes what each frame contains. The crop tool offers presets for 16:9, 9:16, 1:1 and 4:5, or the video's own shape, then a size from 10% to 100% of the largest rectangle of that shape that fits the frame, and a horizontal and vertical position. It keeps the pixels inside the rectangle at their original resolution rather than stretching them back up, so a square crop of a 1920 by 1080 video at full size comes out 1080 by 1080. Width, height and position are always rounded to even numbers of pixels.

The loss from a single re-encode is usually hard to see, but it is real and it adds up across repeated passes. If a video needs several edits, use the copy-only ones where they will do, and keep the number of re-encoding passes as low as you can.

Changing speed and direction

The speed tool plays a video at 0.25x, 0.5x, 0.75x, 1.25x, 1.5x, 2x, 3x or 4x its original speed. It works by re-timing every frame rather than inventing new ones, so it always re-encodes. Speeding up a 30 frames per second clip by 3x or 4x would otherwise produce 90 or 120 frames per second, so the output is capped at 60 frames per second and the extra frames are dropped. Slowing down makes no new frames: each existing frame is held on screen for longer, so a clip slowed to a quarter of its speed shows a quarter as many frames per second.

The sound can be kept or removed. When it is kept, it is re-timed along with the picture the way a tape played faster or slower sounds, which means the pitch rises when the video speeds up and falls when it slows down. There is no pitch-preserving stretch in this tool, so if a changed voice would be distracting, removing the sound is the cleaner choice. Kept sound is encoded at 48 kHz with at most two channels.

The reverse tool plays a clip backwards, sound included. Reversing cannot be done by copying: most frames in a compressed video are stored as changes from other frames, so the tool decodes a short run of frames at a time from the end of the clip and encodes them in the opposite order. To bound the time and memory that takes in a browser, reverse works on clips up to 60 seconds and caps the output at 720 pixels on its short edge, never scaling a smaller video up. For a longer video, trim out the part you want first.

Joining, splitting and looping clips

Merging joins 2 to 10 videos in the order you list them, and you can move clips up and down or remove them before you start. When every clip shares the same video codec and frame size and the same sound settings, and the files' deeper encoder settings match too, the merge copies each clip's compressed data one after another with no re-encoding. That is the usual case for clips from the same camera or phone at the same settings. When they differ, and provided your browser can decode every clip, every clip is re-encoded to the first clip's frame size, with any clip of a different shape fitted inside that frame with black bars. If some clips have sound and others do not, the silent ones are given silence, so the sound of later clips stays in step with their pictures.

The splitter does the reverse: it cuts one video into separate files, either at times you list or into 2 to 20 equal parts, and offers every part individually and as one ZIP. When the codecs allow, each part is copied, which means the same keyframe rule as the trimmer's Fast mode: in some players a part can start before its cut by as much as the gap between two keyframes, and a WebM part always starts at that keyframe. A part can also run a fraction of a second past its end. Files that cannot be copied are re-encoded, provided your browser can decode them, and then every cut lands exactly.

The looper plays a clip 2 to 10 times in a row as one file. When the codecs allow, it copies the clip's data once per play with the timing shifted, so even ten plays take little work. A clip whose codecs cannot be copied, or one that starts with a hidden lead-in left by a fast trim, is re-encoded once, provided your browser can decode it, and that result is then copied for each play. Each play lasts as long as the picture, and the finished loop is capped at 30 minutes.

Pulling stills out of a video

The frame extractor saves still images from a video, either at a regular interval from every half second to every 60 seconds, starting at the very beginning, or at a list of times you type. Each image is the frame showing at that moment, drawn at the video's display size with any rotation already applied, or scaled down to 1280 or 640 pixels wide if you choose. It never scales a small video up.

Images come out as PNG or JPEG. PNG keeps every pixel exactly as decoded and makes much larger files; JPEG is compressed and a fraction of the size, which is usually the better choice for large numbers of frames or for sharing. Because the browser makes the images itself, this tool needs no video encoder at all, only the ability to decode your video.

A run saves at most 500 frames. If an interval or a list would produce more, only the first 500 are saved, and the tool says so before you start. Before it runs, it also estimates how much image data the job would produce, and refuses a job that would come to more than a browser can safely hold in memory; choosing JPEG, a smaller width or fewer frames brings it back within range. The results show the first frames as thumbnails, each with its own download, and every frame is also in a single ZIP.

Limits of editing in a browser

Everything on this page runs inside your browser tab rather than on a server. Your video, its name and its contents never leave your device. If you accept analytics, we record only rough bands for size and length, the output format and the outcome, and for a merge a rough band for the number of files; our privacy notice sets this out.

The trade-off is memory. A browser tab has far less room to work with than a server, so every tool here has limits set by what a tab can hold safely. A single file over 2 GB carries a warning that editing it may be slow and memory-hungry, and a file over 4 GB is refused; for a merge the same 4 GB limit applies to all the clips together. Reverse is limited to 60 seconds, a loop to 30 minutes, a split to 20 parts and a frame extraction to 500 images. A ZIP cannot be made once its contents pass 4 GB, because the ZIP writer used here cannot record sizes past 4 GB; the parts or frames are then offered one at a time instead.

What your browser can encode matters too. Each tool checks before it starts, and when your browser cannot make an MP4 it makes a WebM file instead and says so. These tools read video files, not GIFs: to edit a GIF, convert it to MP4 first with the GIF to MP4 converter.

Questions about quick video edits

Do these video editing tools upload my files?

No. Every tool on this page runs in your browser, on your own device. Your video, its name and its contents never leave your browser. If you accept analytics, we record only rough size and length bands, the output format and the outcome, and for a merge a rough band for the number of files, as our privacy notice explains.

Will editing my video lose quality?

Only when the edit has to re-encode. Rotating, removing the sound, fast trimming, splitting, looping and merging matching clips copy the video without re-encoding when its codecs allow, so nothing is lost. Cropping, flipping, changing speed, reversing and precise trimming always re-encode, which costs a small amount of quality. Each tool tells you which will happen before you start.

Why does a fast-trimmed clip start a little early in some players?

A fast cut starts on the frame that is on screen at your start time, so even in Chrome it can begin up to one frame early. A copy also has to start from a keyframe, so the file begins at the keyframe at or before your start time and hides the frames before the cut with an MP4 edit list. Chrome honours the edit list; a player that ignores it shows those frames, which can be as much as the gap between two keyframes. Choose Precise in the trimmer for a frame-exact cut.

How large a video can I edit?

Files over 2 GB carry a warning that editing may be slow and use a lot of memory, and files over 4 GB are refused. Some tools have their own limits: reverse works on clips up to 60 seconds, a loop can run up to 30 minutes, and a merge takes up to 10 videos and 4 GB in total.