How does Synthesia AI work?
Synthesia turns typed text into video of a lifelike AI presenter. You pick an avatar and a voice, paste your script, and its models generate matching speech and lip-synced facial movements, then render a finished video in your browser. No camera, actor, or studio is needed. It offers 240+ avatars and 1,000+ voices across 160+ languages.
Why — the first-principles explanation
Synthesia replaces the three expensive parts of making a talking-head video, an actor, a camera crew, and an editor, with three AI models working in sequence.
First, text-to-speech converts your written script into natural-sounding audio in the voice you chose. Modern neural voices predict the sound wave word by word, adding pauses and emphasis so it sounds human, not robotic. Second, a video-synthesis model drives a pre-recorded avatar: it takes the audio and generates new mouth shapes, jaw movement, and subtle head motion so the lips match every sound (this is the lip-sync step). Third, the platform composites that avatar onto your slides, background, captions, and brand elements and renders the final MP4 in the cloud.
The avatars themselves are built ahead of time. Synthesia films real actors (or your own personal avatar from a short video) to capture how a specific face looks and moves. The AI then learns to re-animate that captured likeness to say anything you type, which is why one filming session can produce unlimited videos later.
The payoff is editing by editing text. Because the video is generated from a script, fixing a typo or updating a price means changing a sentence and re-rendering, not re-shooting. That decouples video from cameras and turns it into something you update like a document.
An example that makes it click
Imagine a puppet that already knows how to move its mouth. You don't film it, you just hand it a note that says what to say. Synthesia's avatar is that puppet: you type 'Welcome to the team,' and the AI makes the digital face say those exact words with matching lip movements and a chosen voice.
Now imagine you spot a spelling mistake. Instead of re-filming, you erase one word on the note, and the puppet instantly re-says the line correctly. That's the whole trick: the video is glued to the text, so changing the text changes the video.
How to do it
- Sign up at synthesia.io and open the video editor in your browser.
- Pick a template or start blank, then choose one of 240+ AI avatars.
- Type or paste your script into the text box for each scene.
- Select a voice and language from 1,000+ voices across 160+ languages.
- Add slides, images, background, and captions as needed.
- Click Generate; Synthesia renders the finished video in the cloud in minutes.
Key facts
- Synthesia generates video from text using three AI stages: text-to-speech, avatar lip-sync/video synthesis, and cloud rendering.
- The platform offers 240+ stock AI avatars and 1,000+ voices across 160+ languages (as of 2026-07).
- Avatars are pre-filmed from real people, so one recording session can drive unlimited future videos.
- Editing is done by editing the script and re-rendering, not by re-shooting footage.
- Everything runs in a web browser; no camera, microphone, or editing software is required to produce a video.
AI avatar video creation for corporate training and comms.
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How does Synthesia work? It turns typed text into a video of a lifelike AI presenter, no camera or actor needed. Here's the flow. You choose an avatar and a voice, then paste in your script. Behind the scenes, three AI models take over. First, text-to-speech converts your words into natural-sounding audio. Second, a video model drives the avatar, generating new mouth shapes and head movements so the lips match every sound. Third, the platform layers that avatar onto your slides and captions and renders a finished video in the cloud. The clever part is that the avatars are pre-filmed from real people, so one recording session can say anything you type later. And because the video is generated from your script, fixing a typo just means editing the text and re-rendering, not re-shooting. Synthesia offers over 240 avatars and 1,000 voices in more than 160 languages, all inside your web browser.
What authoritative sources say
People also ask
Do I need a camera or actor to use Synthesia?
No. You type a script and choose an AI avatar and voice, and the platform generates the video in your browser. No filming, microphone, or editing software is required.
How does the lip-sync work?
A video-synthesis model reads the generated audio and creates matching mouth and jaw movements on a pre-filmed avatar, so the lips line up with each sound in your chosen language.
Can I edit a Synthesia video after making it?
Yes. Because the video is generated from your script, you edit the text and re-render. There's no need to re-shoot footage to fix a typo or update a fact.
How long does it take to generate a video?
Rendering happens in the cloud and typically takes a few minutes, depending on the video's length and how many scenes it contains.