How do I write a good prompt for Syren? | Synthesia Knowledge Base

A good prompt gives Syren enough context to build a strong first draft. You can start from scratch, from a use case, or from a style, and then refine the video in chat. This article explains how to prompt from each starting point and how to request changes. For the steps to start each way, check out How do I create a video with Syren?

Start From Scratch

Starting from scratch lets you describe the video in your own words. Cover the goal, the audience, and the scope in your prompt, and then add references and brand settings.

What to Include in Your Prompt

A Syren prompt works best when the prompt covers the goal, the audience, and the scope of the video. Start with one sentence, such as "Create a 30-second social media ad explaining Synthesia to marketing professionals interested in video." Then add the details below as needed.

Goal: Describe what the video should do, such as help new hires finish onboarding.
Audience: Name who watches the video and what that audience already knows. Syren adjusts the words, depth, and tone for the audience.
Length: State the length in your prompt. A length of 30 to 60 seconds gives a focused first draft, and shorter videos are easier to review and refine.
Topics: Cover one key topic, or fewer than four topics for an overview. Syren tries to fit in everything you give it.
Story: Describe a problem, some tension, and a resolution. For product explainers, start with the problem and then show the solution.
Vibe: Describe the feel in plain words, such as "playful and energetic, not corporate."
Pacing: State how fast the video moves. If you skip pacing, Syren tends to choose a fast pace.

Here is a prompt that combines these details:

"Create a 45-second onboarding video for sales reps in their first week. Open with the problem: finding the right deck takes too long. Show the new sales hub using the attached screenshots. Keep the pace calm, with a warm and playful tone. End with a call to action to open the sales hub."

Syren can also ask questions while it builds your video, such as who the video is for. Your answers give Syren more context.

How to Add References

References give Syren real material to build from. You can attach documents, images, videos, and PowerPoint files, and add links to your website or YouTube. Only use files, logos, and brand assets you have the right to use.

Attach real screenshots when you want Syren to show your product. Syren shows the screenshot instead of creating a new image.
Describe what each reference is for. Use "flow" for structure, pacing, and the opening. Use "look" for style, color, and texture.
Choose references that look good together. Mixed visual styles give mixed results.

💡 If a link does not pull in the content you expect, paste the HTML of the page into the prompt box.

How to Apply Your Brand

Brand settings control the look of your video. Syren can use a brand kit from your workspace.

Open Syren.
Select a brand kit in the prompt box.
Write your prompt.
- Leave colors and fonts out of the prompt. The brand kit sets them.
Create your video.

If you do not have a brand kit, attach a website link, a deck, or a video that already looks like your brand. Syren picks up the style from that material.

Start With a Use Case

Starting with a use case tells Syren what kind of video you are making, and Syren asks a few questions to collect the material it needs, such as documents, images, and an Avatar. Choose clear, current source material, such as the guide, policy, or handbook that the video is based on. The documents and images you add act as your references, so the tips in How to Add References apply. After the first draft, add anything that is missing in the chat.

Start With a Style

Starting with a style sets the look of every scene, so you do not need to describe the visuals. Syren offers three styles: Motion Graphics, Cinematic, and Cartoon. Syren asks what you want to show, so focus your answers on the story and the content. Add the audience, the length, and the pacing in the chat.

Prompt for a Cinematic Video

A cinematic video responds best to the language of film. Add cinematic details to your prompt, or ask for them in the chat. Describe what the camera sees and how the scene looks, and keep each detail short and specific. Cover these four areas:

Camera: Describe the movement, the framing, and the lens. Name one camera move per shot, such as a slow push-in, a handheld follow, or a static shot. State the framing, such as a close-up or a wide establishing shot. Add a lens look, such as wide-angle for a sense of space or 50mm for a natural view.
Light: Describe the source, the direction, and the quality. Name where the light comes from, such as a window, a lamp, or the sun. State the direction, such as side light, backlight, or overhead light, and the quality, such as soft, hard, warm, or cool. For example, "soft window light from the left."
Color and Texture: Describe the color grade and the film feel. For example, "warm, muted tones with deep shadows and fine film grain." Describe the look in plain words instead of naming a film or director.
Pacing and Composition: State the shot length, the depth, and the subject. For example, "hold each shot for four seconds, with a shallow depth of field and the subject in the left third of the frame." Name one clear subject per shot.

Here is a prompt that covers all four areas:

"Create a 30-second cinematic video for a coffee brand. Open on a wide shot of a quiet café at sunrise, with a slow push-in. Use soft window light from the left and a warm, muted color grade with fine film grain. Hold each shot for four seconds. Keep the barista as the clear subject, with a shallow depth of field."

💡 When you refine a cinematic video, change one area at a time. For example, ask for softer light first, and then ask for a slower camera move.

📌 If you ask for cinematic or realistic content, Syren may suggest cinematic mode in the chat. Cinematic mode is available on paid self-serve plans and uses more credits than a standard video. You choose whether to switch it on.

How to Refine Your Video in Chat

Refining in chat lets you change a video without starting over. Syren uses credits as you create and refine your video, so specific requests help you reach the final video in fewer rounds.

Watch the full first draft before you request changes.
Identify the scene or moment to change.
Describe the change in the chat.
- Name the scene or moment, and state the change you want.
Attach a screenshot or video if you want Syren to match a look or a motion.
Repeat for each change.

Vague and Specific Requests

Specific requests give Syren a clear target. Use these examples as a guide.

Instead of "It feels rushed," write "Slow down scene 3."
Instead of "It's boring," write "The vibe is too corporate. Make the video more playful and whimsical."
Instead of "The visuals aren't right," write "Replace the stock video with this UI screenshot."

💬FAQs

How long can a Syren video be?

A Syren video can be up to 3 minutes on Basic plans, and all paid plans can create a Syren video up to 60 minutes. For a focused first draft, ask for 30 to 60 seconds in your prompt

How long should my Syren prompt be?

A Syren prompt can be one sentence or several paragraphs. Start with a short prompt and add detail in the chat. If a very long prompt fails to generate, shorten the prompt and add the missing detail in the chat.

How do I choose an Avatar for my Syren video?

To choose an Avatar, name the Avatar in your prompt, such as "Use [Avatar name] as the presenter." Syren can use Synthesia stock Avatars and Avatars you create with Avatar Builder, as long as your account has permission to use them. If you do not name an Avatar, Syren chooses one for you.

What should I do if the chat stops responding?

If the chat stops responding, reload the page, and then type continue in the chat.