How to Auto-Trim, Add Subtitles and Motion in an Online Video Editor

You don't need to install heavy software to edit videos anymore. With video97, you can cut, trim, add AI subtitles, and even create motion effects right in your browser. This guide shows you how to take a raw recording with awkward pauses, remove those pauses automatically, add animated captions, and turn the whole thing into a motion video. By the end, you will have a polished MP4 file ready to share.

What You Need Before You Start

• A video file: an MP4, MOV, or WebM file from your phone, camera, or screen recorder.
• A modern browser: Chrome, Edge, Firefox, or Safari. video97 works best with the latest version.
• A stable internet connection: the app runs in the browser, so uploads and exports use the network.
• No software to install. No account is needed to start, though you may need to sign in if you want to save your project later.

Make sure your video has clear speech. The AI uses the audio to detect silence and generate subtitles. If the recording is very quiet, you may need to use the built-in audio enhancer first.

Step 1: Open the Online Video Editor and Upload Your Clip

1. Go to video97.com.
2. Click the button "Open the AI video generator" or the "New project" button. The exact label might change, but it is usually obvious.
3. In the upload area, drag and drop your video file. You can also click to browse your folders.
4. Wait for the video to process. The browser may take a few seconds or a couple of minutes depending on the file size.

Once the video is loaded, you will see it on the timeline. This is your working area. You can play it, pause it, and scrub through it to inspect the content.

Step 2: Auto-Trim Dead Air and Pauses with AI

Dead air is any part of the audio where the speaker is silent, not counting natural pauses between sentences. Removing these long gaps makes your video feel tighter and more professional.

How to remove silence automatically

• Look for the "Trim" or "Cut" tool in the toolbar. In video97, this is usually in the "Edit" or "Video" section.
• Click "Remove silences" or "Detect silence". The AI will scan the audio track and mark the quiet segments in yellow or red on the waveform.
• Adjust the silence threshold if needed. The default is usually good, but you can increase the sensitivity to remove shorter pauses too.
• Click "Apply" or "Remove". The editor will delete those parts and close the gaps.
• Play the result. If some pauses were removed that you actually wanted, use the undo button and tweak the threshold.

Manual trimming

If you prefer granular control, you can also trim manually:

• Drag the left or right edge of the clip on the timeline to cut off the beginning or end.
• Use the split tool to divide the clip at a specific point, then delete the silent section in the middle.
• Zoom in on the waveform to find the exact frame where speech starts and ends.

After trimming, your video should flow from sentence to sentence. If you are unsure whether a pause is too long, listen to a few sections. The goal is to remove empty gaps, not to cut natural pauses that help the audience breathe.

Step 3: Add Subtitles to Your Video with AI

Subtitles are one of the most important things you can add, especially for social media. Most people watch videos without sound on platforms like Instagram or LinkedIn. AI-generated subtitles save you hours of typing.

Generate the automatic subtitles

• Click the "Subtitles" tab in the video97 interface.
• Press "Generate" or "Auto subtitles". The AI transcribes the audio and creates a subtitle track.
• Wait for the transcription to complete. The process is usually fast, but longer videos take more time.
• The subtitles appear on the preview and on the timeline as text segments.

Edit the subtitles

• Click on any subtitle block in the timeline to edit its text, start time, or end time.
• If the transcription made a mistake, correct it here. Pay attention to names, technical terms, and homophones.
• You can also merge or split subtitle blocks if the timing feels off.

Style the captions

• Choose a font, size, and color from the subtitle settings. Make sure the text is easy to read against your footage.
• Add a text background or outline for better contrast. In video97, you can select a box or a stroke.
• Position the subtitles in the lower third of the video, or try the upper area if your video has important visuals at the bottom.

Step 4: Make Motion Video with Animated Subtitles and Effects

Motion makes your video feel alive. For a talking head, motion can mean a subtle zoom to keep the frame from feeling static. For a slideshow, it can mean panning across images. You can also make subtitles themselves move.

Animate the subtitles

• In the subtitle settings, look for "Animation" or "Motion".
• Choose a preset like "Pop", "Slide", "Fade", or "Typewriter".
• Adjust the speed and easing. For example, a fast pop works well for short clips; a gentle fade is better for longer, calmer videos.
• Preview the result. The subtitles will animate when the text appears and disappears.

Add motion to the video layer

• Select the video clip on the timeline.
• Open the "Motion" or "Transform" panel.
• To create a Ken Burns effect, set a zoom from 100% to 110% or 120% over the clip's duration. The camera will slowly push in or pull out.
• You can also add horizontal or vertical panning if your video is not centered.
• For a talking head, a slow zoom keeps the viewer focused and prevents boredom. For a vlog, a slight rotation can add energy.

Use motion graphics and overlays

• video97 includes a library of animated graphics: shapes, lines, icons, and backgrounds.
• Add a lower third with a name or title, and animate it to slide in and out.
• Use an animated background if your original video has a plain wall. You can mask yourself out or place the video over a custom graphic.

Remember to keep it simple. Too many effects can distract from your message. One or two motion elements are enough to make the video feel dynamic.

Step 5: Add Music or Voice-Over (Optional but Recommended)

Even after trimming, your video may feel too quiet. Adding a background track changes the energy. In video97, you can add music from the library or upload your own. If you want a professional voice-over, you can use the built-in AI voice-over tool.

• Click the "Audio" or "Music" tab.
• Browse the free music tracks. Many are loopable and split into moods like energetic, calm, or cinematic.
• Drag a track onto the timeline. Adjust its volume so it sits under the voice track.
• For a voice-over, click "Add voice-over", then type a script or choose a language and voice style. The AI will generate a natural-sounding narration.
• Sync the voice-over with the video. You can trim it or shift it on the timeline.

Music can hide background noise and make your pacing feel smoother. Just make sure the volume is low enough that your speech is still clear.

Step 6: Export Your Video as MP4

• Press the "Play" button to watch the full video from start to finish.
• Check the subtitles for typos, and verify that the motion effects don't cause dizziness.
• Click "Export" in the top right corner.
• Choose a resolution. 1080p is best for YouTube and social media; 720p is fine for quicker uploads.
• Wait for the export to finish. Because video97 processes in the browser, your computer may be busy during this time. Keep the tab open.
• Once the export is done, click "Download" to save the MP4 to your device.

Your video is now ready to share. You have trimmed the dead air, added animated subtitles, and made it a motion video, all without leaving your browser.

FAQ

Is video97 really free?

Yes. video97 is a free online video editor. You can edit and export videos without paying a subscription. There are no watermarks on exported MP4 files unless there is a paid plan for extra features, but the core editing tools are free.

How accurate are the AI subtitles?

The AI transcription is usually very accurate for clear, English speech. Background noise, strong accents, or muffled audio can cause errors. You can always click on a subtitle block and type the correct text. It takes only a few minutes to check and fix a short video.

Can I use these steps for any video file?

Yes. As long as your video is in a common format like MP4, MOV, or WebM, you can upload it. The AI features work on the audio and video inside that file. If you have a very large file, it may take a bit longer to upload and export, but the steps remain the same.