HeyGen and Synthesia: a count, or a code per voice
One documents thirty or more languages for video translation, with cloning and lip-sync in the same sentence. The other publishes a formal name, a native name and a code on each voice. A workflow claim against a catalogue. From 3 source pages, read 2026-09-22; no maker pays to be listed.
| Field | HeyGen | Synthesia | Where they part |
|---|---|---|---|
| Audio source | From a speech endpoint, then rendered | From the script, or uploaded | Different answers |
| Voice source | A recording to clone from | A catalogue voice, or a cloned one | Different answers |
| Per-character binding | On a stored clone | Not documented by the vendor | Only HeyGen answers |
| Languages | A count, attached to translation | A catalogue with codes | Different answers |
| Lip-sync | Named, alongside translation | The spoken content, framed close | Different answers |
Inclusion rule. Two entries are given a page together when at least one column puts them at opposite grades of answer. Pairs that agree on every column, or that are both blank throughout, do not get a page. Order. Fixed field order, identical on every side-by-side page.
1Where a language figure sits tells you what it is for
A count attached to translation describes reaching markets by translating a finished master: one performance, one set of frames, and a localisation stage at the end. A catalogue with codes describes choosing a voice for a market before anything is made.
Those are different production plans with different risks. Translating concentrates the work and the risk in one master; choosing per market spreads both, and keeps a bad episode from reaching thirty places at once.
2One threshold, one condition, and both worth copying
One publishes twenty minutes or more of audio for a professional clone, which turns cloning into a booked session rather than a feature. The other publishes a framing condition, saying lip sync performs better with the avatar closer to camera.
Both are sentences that change a plan rather than a preference, and both are rare. Most entries in this register publish neither a threshold on their inputs nor a weak case for their outputs.
3Cloning across thirty languages raises a question neither answers
Naming voice cloning next to a language count implies a performer's voice travelling into markets they never discussed. The mechanics are documented on both platforms and the permission is on neither.
This register records the mechanism because that is what a page can settle. Who may lawfully be cloned, and in how many languages, is decided by a release form that no API quick start contains.
4Each of them on its own
The column this pair was chosen for is languages, and each entry has a page of its own on it. The full row for either, all five columns with the wording behind each cell, is on its model note.
- HeyGen on languages — a count, attached to translation.
- Synthesia on languages — a catalogue with codes.
- HeyGen, all five fields — read from the API quick start.
- Synthesia, all five fields — read from the voices reference and avatar documentation.
5Where HeyGen and Synthesia part, a third entry's answer
| Field | SceneMixer |
|---|---|
| Audio source | With the picture, in the language set for the project |
| Voice source | A preset library, or the user's own recordings |
| Per-character binding | On the character |
| Languages | A named list, set per project |
| Lip-sync | The new audio, when a line is redubbed |
Inclusion rule. The columns on which the two entries above give different answers, each with SceneMixer's answer from its own model note. Order. Fixed field order, identical on every side-by-side page.
- LanguagesVideo translation is documented for thirty or more languages, with voice cloning and lip-synccounted on the translation endpoint
- Voice sourceA voice clone is instant from one recording or professional from twenty minutes or more, and is then passed as a voice idtwo enrolment routes with a threshold
- LanguagesEach voice is listed with its formal and native language name, a language code, a gender, a name and a voice idpublished as a catalogue with codes
- Voice sourceVoice cloning carries a language list of its own, running from Afrikaans to Zulu and described as the same list used for standalone cloninga cloned voice with its own reach
- A framing condition attached to lip-syncLip sync performs best when the avatar is framed closer in the scene rather than positioned far from the camera
6Sources
Every cell above is read from the documentation each vendor publishes, on the dates carried by the two model notes. The whole register on one column is on the field note; entries grouped by the shape of their answer are on the routes. Other pairs: Kling AI and Synthesia, SceneMixer and Synthesia.