Play a Video Clip Backwards for Effects

A glass that un-spills, a diver who leaps out of the pool, a rewind transition for a birthday video, a loop that plays forward and back forever. Reversed clips are one of the oldest tricks in video, and one of the few effects that needs no skill beyond choosing the right clip. The tool only has to play every frame in the opposite order, and there is one practical catch that decides how long a clip you can reverse in a browser.

The short version: drop a short clip into Reverse Video, press Reverse, wait for the progress bar, and download an MP4 that plays backwards, picture and sound.

What the tool does

Reverse Video plays a clip backwards. It reverses the picture and the sound together, and the result is always an MP4. All the processing happens on your device, so the clip is not uploaded to a server. The first time you use any of the video tools, the browser downloads a processing engine of about 25 MB from a public network, so allow a moment for that. Your original file is never changed, and the new file is named after the original with "-reversed" added, so beach.mp4 gives beach-reversed.mp4.

There is one checkbox: Shrink to 480p so a longer clip fits in memory. It does what it says, and the next section explains why it matters.

Why length is the limit

Reversing is different from most video edits. To play frame 300 first, the tool has to hold frames 1 to 300 in memory before it can start. That means the longest clip you can reverse in one go depends on the size of the picture and the number of frames per second, not on the file size.

The tool works from a memory budget of about 700 MB for one piece, and it counts each frame as width times height times one and a half bytes. That gives these piece lengths at 30 frames per second:

• 1280 by 720 (720p): up to 16 seconds in one piece.
• 1920 by 1080 (1080p): up to 7 seconds.
• 854 by 480 (the 480p option): up to 37 seconds.
• 3840 by 2160 (4K): only about 1 second.

Frame rate matters too. A 1080p clip at 60 frames per second halves the figure to about 3 seconds per piece, because there are twice as many frames per second to hold.

Long clips are done in pieces

A clip longer than one piece is not refused. The tool cuts it into pieces that fit, reverses each piece, and then joins the pieces last to first, so the whole clip plays backwards. So a 10-second 1080p clip at 30 frames per second is already two pieces. A 30-second 1080p clip is done as 4 pieces of up to 7.5 seconds, and a 2-minute 1080p clip becomes 16 pieces. The progress bar says "part 3 of 16" so you know how far along it is, and the tool shows a note afterwards that tells you how many pieces it used.

This has two consequences you can plan for. First, it takes longer than a one-pass job, so be patient with a long clip and keep the tab open. Second, the sound may click briefly where the pieces meet. The tool says so in its note. For a short effect clip you will never hear it, and for a long one with music, consider reversing only the picture (see below).

There is a hard ceiling because the number of pieces is capped at 150. In practice that means about 1,125 seconds, nearly 19 minutes, at 1080p and 30 frames per second, and about 5,625 seconds at 480p. A 50-minute 1080p recording is therefore refused with a message that says about how long a clip it can handle at that size and suggests trimming first, and ticking the 480p option to allow more. For 4K the ceiling is much lower, about 225 seconds. That is not a limit anyone will notice for the kind of clip people reverse, which is usually five to fifteen seconds long.

Choosing the right clip

The best clips to reverse are short, have one clear action, and look interesting going backwards. Water, smoke, dust, paint, confetti, hair, a ball bouncing and a person walking away from the camera all work. Clips with writing do not, because the text will not read right, and clips with a person speaking sound strange in reverse. Trim away any pause before the action starts and any still frames at the end, because both become the first and last seconds of the reversed clip.

If the clip is longer than the action, cut it first. Trim Video shortens the clip to the seconds you want, and a shorter clip reverses faster and avoids the piece joins altogether. If your clip is a phone recording at 4K, trim it first, tick the 480p option or accept that it will be reversed in pieces of a second or two.

What to do with the sound

Reverse Video reverses the sound as well. For some effects that is right, such as a splash in reverse. For others it is wrong. A reversed song or a reversed voice sounds like noise, and a reversed room tone can add an odd swell. If you want the picture reversed with no sound, the cleanest route is to remove the sound from the original first with Mute Video and then reverse the silent copy. Mute Video copies the picture without re-encoding when it can, so nothing is lost. The sound is only worth keeping when the reversed noise is part of the effect. You can then add your own music in your editor.

Size, quality and sharing

The result is re-encoded as an MP4 in H.264, at a quality setting that keeps most detail. That means a reversed clip is a new encode rather than a copy, and a very detailed picture may be slightly softer than the original. If the output is larger than you want to send, Compress Video reduces it. Compress after reversing, not before, so the reverse step works from the best picture.

The trial allows files up to 50 MB, and a paid plan allows up to 200 MB. Phone clips are usually small enough when they are short, but a 20-second 4K clip can pass 50 MB, so trim it first or choose a lower resolution on the phone.

Making a forward-and-back loop

A reversed clip is also half of a loop. The recipe is: reverse the clip, then join the original and the reversed copy with Merge Video, original first. The result plays forward and then backwards, and when it repeats the movement looks continuous. It works best when the action begins and ends at roughly the same position, such as a swing, a wave or a bounce. Do not expect it to disguise a clip where someone walks across the frame, because the end of the first half and the start of the second half match perfectly but the movement itself looks odd.

Steps

1. Trim the clip to the moment you want, ideally under ten seconds, using Trim Video.
2. If you want silent output, remove the sound with Mute Video first.
3. Open Reverse Video and drop in the clip.
4. Tick the 480p option only if the clip is long or the tool says it is too long at full size.
5. Press Reverse and wait. A longer clip shows part numbers as it works.
6. Watch the preview, then download the MP4.
7. Reduce the size with Compress Video if it needs to be emailed.

The tool is a Professional Tool with 10 trial uses a day, then a $1 day pass or the $4.99 monthly plan.

Common mistakes

Dropping in a long, high-resolution recording and expecting it to finish in seconds. Reversing a clip with spoken words and being surprised it sounds like gibberish. Forgetting that on the trial the file must be under 50 MB. Reversing before trimming, so the tool spends minutes on footage you will throw away. Closing the tab in the middle of a multi-part job. And ticking 480p on a short clip that would have fitted at full size and lost detail for nothing.

Summary

A reversed clip takes seconds to make once you understand the one constraint: frames have to fit in memory. Reverse Video handles short clips in one pass, longer clips in joined pieces, offers a 480p option for length, reverses the sound with the picture, and tells you plainly when a clip is too long. More tools for video are in the video tools category.

Open Reverse Video→

What is the best backwards clip you have made? Tell us on the contact page.