Griffin-style listening beats in a recorded avatar video: what works

Tavus describes Griffin as a full-duplex avatar: it listens and talks at the same time, gives backchannels such as "mm-hm", and stops when you interrupt it. The page says it generates 720p video in 320 millisecond chunks, with 0.43 seconds from audio to video on H100 GPUs, from a single user photo. It also says Griffin-Lite is a research preview for select testers and not available to customers. I read the page on 2026-10-04.

Those are live conversation traits. A recorded Sume avatar video does not listen, since nobody is in the loop. What you can borrow is the pacing.

What a recorded video can and cannot do

Borrowing the pacing: silence beats

A talking-head video that never pauses feels like a recording. Sume's video_inputs lets you add scenes with voice.type: "silence", which are beats with no speech and a required duration. Use a one or two second beat after a question, as if the avatar were waiting for an answer. The total planned duration must still fall between 4 and 60 seconds, and one avatar and one shared scene serve the whole video.

What the avatar's face does during a silent beat is up to the model. The docs do not promise a nod, so check it on a preview before you pay for a render.

curl -X POST https://api.sume.com/v1/avatar-video-previews \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"avatar_handle":"@host","aspect_ratio":"9:16","video_inputs":[{"id":"q","voice":{"type":"text","script":"Ever wonder why your first cut is never the best one?","duration":4}},{"id":"beat","voice":{"type":"silence","duration":2}},{"id":"a","voice":{"type":"text","script":"Because you were still deciding what to say.","duration":4}}]}'

Cost of the test

A 10 second video at standard costs 10 x $0.184 = $1.84, and at plus $2.45. The preview comes first, and its still does not change with the tier you choose later.

When you actually need Griffin-style

If the viewer must talk back, you need a real-time avatar product, and Sume does not ship one. Griffin-Lite is not open to customers per the Tavus page. For a one-way message, the silence beat gives a conversational rhythm at a known per-second price.