How to add captions in your own colours with sparkle effects

Last updated 2026-08-23 · 6 min read

What is the short version?

Captions in specific colours with a specific overlay sounds like a preset and is not. The caption has to match the speech precisely, and the overlay has to blend correctly over your footage, which depends on how that particular effect file was made.

1. Go to Vizard Agent and upload the clip.
2. Name the caption colours — the fill and the outline.
3. Name the effect you want over the top.

What do you need before you start?

The clip and your colours. Vizard Agent transcribes the speech and sources the overlays itself, so nothing needs preparing, and being specific about the colours is worth doing because "bright" and "festive" produce a different result from a named pair.

• The clip. Any length; short is the usual case.
• The colours. The text fill and the outline, named plainly.
• The effect. Sparkles, fairy lights, gold dust, snow.
• The audio. Whether the voice needs cleaning up first.
• A plain version too. Text only, without the overlay.

What do you type into Vizard Agent?

Name both colours. Vizard Agent renders a style test before it commits, and a specific pair — yellow text with a lime green outline — gives it something exact to hit rather than an interpretation of a mood.

Prompt

Variants worth knowing:

• Clean up the voice first. Worth it if the recording is noisy.
• Two versions. Text only, and text with the effect, from the same render.
• A different overlay. Vizard Agent will compare several before choosing.

What does Vizard Agent actually do?

Here is the order Vizard Agent worked in on a real captioned clip. The stretch in the middle is a debugging session: the first sparkle overlay did not blend correctly, and Vizard Agent went into its colour channels to find out why.

1. Probes the clip, transcribes the audio and extracts frames to review.
2. Analyses the audio track and the vocal activity to find where the speech actually sits.
3. Checks the exact timings of each spoken phrase and extracts frames of the speaker to confirm.
4. Cleans up and enhances the voice, then re-transcribes the cleaned audio.
5. Searches for and downloads several sparkle and fairy-light elements and compares samples.
6. Tests the sparkle overlay over the footage and finds it blending incorrectly.
7. Analyses the overlay's colour channels and corrects the blend in the right colour space.
8. Compares four combinations — stars alone, stars with lights, lights with bokeh, stars with gold dust — on real frames.
9. Renders a style test for the exact colour pair, calculates the speech timings precisely, renders the final video, then produces a second version with the text only.

Step 7 is the unglamorous one. An overlay that looks grey and flat over your footage is usually a colour-space problem rather than a bad effect, and diagnosing it takes reading the channels rather than trying another file.

What does the result look like?

From the run this page is written from, probed on the delivered file: 1080x2460, H.264, 23.81fps, 12.05 seconds, AAC audio. Twelve seconds at the phone's own tall resolution, captions in the requested colours timed to the speech, with the sparkle and light overlay composited on top.

Keeping the source's unusual dimensions and frame rate rather than normalising them matters here. The clip was shot on a phone with a tall screen, and re-encoding it to a standard shape would crop or letterbox it for no reason.

When does this not work well?

Captions depend on the speech being clear enough to transcribe, and overlays depend on the footage having visual room for them. Vizard Agent cleans up the audio and tests the blend on real frames, and both of those have limits that the source material sets.

• Unclear speech transcribes badly. Vizard Agent enhances the voice first and there is a ceiling.
• Busy footage fights an overlay. Sparkles over a bright, detailed shot read as noise.
• Strong colours can clash. Vizard Agent renders a style test so you see it before the full render.
• Overlays cover the picture. Say if the subject's face must stay clear.
• Children in videos need care. Anything published featuring a child is a decision beyond the edit.

How do you fix a result that came back wrong?

Say what is off. Vizard Agent keeps the cleaned audio, the precise speech timings, the style tests and every overlay combination it compared, so changing the colours or the effect is a re-render rather than a fresh pass.

• "Use the gold dust version." Already compared and rendered on frames.
• "The outline is too thin." Restyled and shown as a test first.
• "A word is wrong." Corrected against the cleaned transcript.

How does Vizard Agent compare to doing it yourself?

By hand this is typing the captions out and nudging each one into sync, downloading an overlay that comes out grey and flat over your footage, and then trying three more files without ever knowing why the first one failed.

Common questions

Why does an overlay come out grey? Because of how it was encoded rather than how it looks. A sparkle element made for a screen or add blend will sit flat over your footage until it is composited in the right colour space, which is what Vizard Agent diagnosed by reading the effect's channels on this run.

Can I name exact colours? Yes, and it is worth doing. Vizard Agent renders a style test to show you before committing.

Will the captions match the speech? Yes. Vizard Agent measures the phrase timings precisely rather than estimating.

Can it clean up the audio first? Yes, and it re-transcribes the cleaned track for better accuracy.

Can I get a version without the effect? Yes. Vizard Agent produced both on this run from the same work.

What effects are available? Sparkles, fairy lights, bokeh, gold dust and more. Vizard Agent downloads several and compares them composited over your own footage before choosing.

Can Vizard Agent keep the face clear? Yes. Say so and Vizard Agent places the overlay and the caption band away from the subject rather than across them.

Does this work for other occasions? Yes. The same method covers birthday confetti, summer light leaks, snow or any seasonal overlay — what changes is the element, not the process.

Does Vizard Agent check the result? Yes. It renders a quality-control grid from the finished file and inspects it before the video is delivered.

Does it keep my video's shape? Yes. This run delivered at 1080x2460, exactly as the phone recorded it.