RecordVideo producing black screen

[patchmeifyoucan]

Hello,

I am trying to use the gymnasium RecordVideo wrapper to capture my episodes. While it works perfectly
with other environments, with MuJoCo environments I experience strange behavior. The problem is that
only the first run within an environment instance is recorded correctly. I did not find a way to fix it properly.

One possible way to do it is to recreate both the environment and recorder instance every time I perform
test rollouts, so the issue seems to be related to some internal state which I do not have access to.

Find the code to reproduce the issue below.

import uuid

import gymnasium as gym

env = gym.wrappers.RecordVideo(
    env=gym.make("Humanoid-v4", render_mode="rgb_array"),
    video_folder=f"video/{uuid.uuid4()}",
    episode_trigger=lambda x: True,
    disable_logger=True
)

for i in range(3):
    env.reset()
    done = False
    while not done:
        next_state, reward, terminated, truncated, info = env.step(env.action_space.sample())
        if terminated or truncated:
            break

I am using

• Ubuntu 22.04
• MuJoCo 2.3.3, gymnasium 0.28.1 and Python 3.10

Thank you very much for your help.

[yuvaltassa]

Please report to gym maintainers, MuJoCo is not associated with this project.
Cheers