NVIDIA / NVIDIA/cosmos-framework

Clarification on shared vs. independent flow timesteps for video and action

Open
#209 0 comments 0 reactions 2 assignees View on GitHub

@fwd4 is already working on this.

Since Aug 19, 2026.

Dominant language
Python
Stars
535
Forks
148
Avg merge
13h 37m
Merged PRs (30d)
35

Description

Hi Cosmos team,

Thanks for releasing Cosmos 3 and the training code. I have a question about the flow timestep sampling for joint video-action training.

The technical report states that noise levels are sampled independently for each modality. However, in the current code, when independent_action_schedule=False, the action sigma/timestep appears to reuse the vision sigma/timestep:

sigmas_for_action = sigmas if sigmas_action is None else sigmas_action

and the default configuration seems to set:

independent_action_schedule: false

Could you please clarify:

Were the released Cosmos 3 action/mid-training checkpoints trained with independent video/action timesteps (independent_action_schedule=True) or with shared timesteps?

Is the default False setting intentional for post-training only, or does it also reflect the original mid-training setup?

Thanks for the clarification!

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Assessment

This issue has not been assessed yet.

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.