How to Close character mouth?

Unity Questions
1

Hi, I am facing 2 issues with Lipsyncing in Unity with Realusion CC4 character.
The lipsync works fine 4/5 times so it means the settings are correct. It occurs with multiple different character, different voices (GCP, Azure, Elevenlabs, Open AI).
Issue 1: The character keeps mouth closed while audio plays.
Issue 2: The character kepps mouth open even after audio finishes.

Issue 2 is a big issue since if no users start a conversation for a while the character just stands there with it’s mouth wide open which looks really bad.

Is there a way to programatically close the mouth, we can add this code after we get the event that the character stops talking. At least this way it won’t look too unprofessional.

If the issues can be resolved, that would be great.

Character ID : e1251142-7f48-11f0-9366-42010a7be01f (but happening with all our characters)
Character description : only 80 words
Character Voice : All voices
Character AI LLM : gpt-4.1-nano
Character knowledge bank : no files at all
Country : India
Platform : Unity

2

Hello @asmita,

Could you share a video? Make sure the logs are visible.

3

Can you provide a private messaging system as the project is under NDA

4

Hi, I shared a video and logs on DMs. Kindly respond urgently as this is a Live project. Thanks

5

Thanks for the details. In ConvaiNPC.cs, please try increasing BUFFER_TIMEOUT to 3 or 4 (and adjust higher if needed) to see which value stabilizes the behavior.

6

I have the same problem too, but in the script you mentioned I don’t have BUFFER_TIMEOUT, only these constants:

Screenshot 2025-09-09 153130
Screenshot 2025-09-09 153130777×229 33.4 KB

7

Make sure you are using the latest version.

1 Like
8

I’ve updated to version 3.3.1, and setting the constant to 4 seems to work well.

9

I changed the value to 3 and kept increasing 1-by-1 to 8 but nothing helped.
I am on version 3.3.0 which I got from Unity assetstore.

10

Hi, I know with my Reallusion characters after I have imported them from CC4 into Unity the Jaw Bone field assignment in the Rig setup has to be given the value of “None” otherwise the jaw hangs open. Once “None” is assigned (just delete whatever is in the Jaw Bone Root field in rig setup I think it is) the character operates normally afterwards, talking etc works. Please do a backup if you’re going to try this.

11

Thanks for helping, but everything has already been setup correctly. the character talks normally 2/3 times that means settings are correct.

1 Like
12

Ok no problem.

13

@K3 please help urgently. why is this only happening with ElevenLabs voice? we need this voice because of low latency. OpenAI voice lipsync works well but has too much latency (8-12 sec).

14

Hi, yesterday I updated the API and set the constant to 4. It seemed to be working, but today sometimes the mouth moves and sometimes it doesn’t. Additionally, with the new API update, I’m noticing quite long response times.

15

Could you please try again?