Back to Blog
Tutorials4 min readJuly 13, 2026

Effortless Composite Captions: Text Behind Your Subject Automatically

Discover how to create stunning composite captions that render text behind your subject in videos effortlessly, without any manual work.


Introduction

Every video creator knows the struggle of making captions visually appealing while ensuring they complement the subject in the frame. Traditional captioning methods often fall short, overlaying text that can distract from the video’s focal point. Enter Composite Captions, a revolutionary way to place captions behind the subject automatically, enhancing the visual storytelling of your videos.

What Are Composite Captions?

Composite Captions are a feature in Sleepy Motion that allows for stunning motion-graphics subtitles, rendering text behind the subject in a video. Unlike traditional captioning tools that simply overlay text, Composite Captions leverage advanced automatic subject segmentation. This means that the engine identifies the subject in the video and masks them, allowing the text to sit seamlessly behind. The result? A polished look that mimics the labor-intensive process of manual rotoscoping in After Effects—without any of the effort.

The Difference Between Plain Subtitles and Motion-Graphics Subtitles

Let’s clarify the distinction:

  • Plain Subtitles: These are basic captures of spoken words, often just static text overlaid on the video. They lack depth and can easily become background noise.
  • Motion-Graphics Subtitles: These are dynamic and visually engaging, like the Composite Captions system. They enhance the video narrative, ensuring that text interacts with the visual elements without distraction.

For example, if you’re showcasing a product in a reel, plain subtitles can detract from the product visuals. In contrast, motion-graphics subtitles can frame the product, making the information pop without overshadowing it.

How to Create Composite Captions Easily

Creating Composite Captions is simple. Here’s how:

  • Upload Your Video: Supported files are vertical MP4s, under 150MB, with a maximum length of 30 seconds for Free, Starter, and Creator plans, or up to 2 minutes for the Agency plan.
  • Automatic Processing: Once uploaded, the Sleepy Motion engine automatically detects speech, masks the subject, and renders graphics behind them. That’s it! No manual adjustments or rotoscoping required.
  • Review and Download: After processing, review your composite captions and hit download. It’s that straightforward.

Example Use Cases

  • Short-Form Creators: If you’re a TikTok or Instagram Reel creator, Composite Captions can elevate your content. For instance, a cooking video where you explain steps can benefit from motion-graphics subtitles that highlight key ingredients behind you, ensuring the focus remains on both you and the cooking process.
  • Paid Ads: For marketing professionals, Composite Captions add a layer of sophistication to ads. Imagine a fashion brand’s ad where the model walks down the runway, and subtitles appear behind them, emphasizing sale messages or product details. This makes the ad visually striking and keeps the viewer’s attention on the brand.

Troubleshooting Common Issues

While the Composite Captions process is designed to be seamless, here are a few tips for common hiccups:

  • Subject Masking Issues: If the engine struggles to mask the subject properly, ensure the video has good lighting and clear edges around the subject. Dark backgrounds can confuse the automatic masking.
  • Text Visibility: If the text isn’t contrasting well with the background, try adjusting the color palette of your graphics during the review stage. Sleepy Motion allows for some customization.

Conclusion

Using Composite Captions transforms how creators engage with their audience. They serve as an elegant solution for anyone looking to enhance their video content without adding complexity to the workflow. With automatic subject masking, you can place text behind the subject effortlessly—perfect for short-form videos and ads. Say goodbye to manual adjustments and hello to captivating visuals that elevate your storytelling.

FAQs

  • What are Composite Captions?
Composite Captions allow you to place motion-graphics text behind the subject in a video automatically, enhancing visual appeal.
  • How do I create Composite Captions?
Just upload your video (vertical MP4, max 150MB) and the engine will automatically create the captions.
  • What’s the difference between plain subtitles and motion-graphics subtitles?
Plain subtitles overlay text, while motion-graphics subtitles create depth by rendering text behind the subject, making them more visually engaging.
  • Can I use auto language detection subtitles?
Yes, Sleepy Motion supports auto language detection, making it easy to create captions in various languages based on the spoken content.
  • What formats does Sleepy Motion support?
Sleepy Motion primarily supports vertical MP4 videos with a maximum size of 150MB for most plans.
  • How long can my video be for Composite Captions?
Videos can be up to 30 seconds for Free, Starter, and Creator plans, and up to 2 minutes for the Agency plan.

Frequently Asked Questions

What are Composite Captions?

Composite Captions allow you to place motion-graphics text behind the subject in a video automatically, enhancing visual appeal.

How do I create Composite Captions?

Just upload your video (vertical MP4, max 150MB) and the engine will automatically create the captions.

What’s the difference between plain subtitles and motion-graphics subtitles?

Plain subtitles overlay text, while motion-graphics subtitles create depth by rendering text behind the subject, making them more visually engaging.

Can I use auto language detection subtitles?

Yes, Sleepy Motion supports auto language detection, making it easy to create captions in various languages based on the spoken content.

What formats does Sleepy Motion support?

Sleepy Motion primarily supports vertical MP4 videos with a maximum size of 150MB for most plans.

How long can my video be for Composite Captions?

Videos can be up to 30 seconds for Free, Starter, and Creator plans, and up to 2 minutes for the Agency plan.

composite captionsmotion graphics subtitlesvideo captionsautomatic maskingcaptioning tools