Fix video recorder and add test (#2063)

* Fix video recorder and add test

* Update github CI

* Install ffmpeg

* Revert "Update github CI"

This reverts commit 07791e9.

* Skip VecVideoRecorder test on github

docs/misc/changelog.rst

@@ -3,7 +3,7 @@
 Changelog
 ==========
 
-Release 2.5.0a0 (WIP)
+Release 2.5.0a1 (WIP)
 --------------------------
 
 Breaking Changes:
@@ -42,6 +42,14 @@ Documentation:
 - Add FootstepNet Envs to the project page (@cgaspard3333)
 - Added FRASA to the project page (@MarcDcls)
 
+Release 2.4.1 (2024-12-20)
+--------------------------
+
+Bug Fixes:
+^^^^^^^^^^
+- Fixed a bug introduced in v2.4.0 where the ``VecVideoRecorder`` would override videos
+
+
 Release 2.4.0 (2024-11-18)
 --------------------------
 

stable_baselines3/common/vec_env/vec_video_recorder.py

@@ -29,6 +29,9 @@ class VecVideoRecorder(VecEnvWrapper):
     :param name_prefix: Prefix to the video name
     """
 
+    video_name: str
+    video_path: str
+
     def __init__(
         self,
         venv: VecEnv,
@@ -50,7 +53,7 @@ def __init__(
 
         if isinstance(temp_env, DummyVecEnv) or isinstance(temp_env, SubprocVecEnv):
             metadata = temp_env.get_attr("metadata")[0]
-        else:
+        else:  # pragma: no cover # assume gym interface
             metadata = temp_env.metadata
 
         self.env.metadata = metadata
@@ -67,15 +70,12 @@ def __init__(
         self.step_id = 0
         self.video_length = video_length
 
-        self.video_name = f"{self.name_prefix}-step-{self.step_id}-to-step-{self.step_id + self.video_length}.mp4"
-        self.video_path = os.path.join(self.video_folder, self.video_name)
-
         self.recording = False
         self.recorded_frames: list[np.ndarray] = []
 
         try:
             import moviepy  # noqa: F401
-        except ImportError as e:
+        except ImportError as e:  # pragma: no cover
             raise error.DependencyNotInstalled("MoviePy is not installed, run `pip install 'gymnasium[other]'`") from e
 
     def reset(self) -> VecEnvObs:
@@ -85,6 +85,9 @@ def reset(self) -> VecEnvObs:
         return obs
 
     def _start_video_recorder(self) -> None:
+        # Update video name and path
+        self.video_name = f"{self.name_prefix}-step-{self.step_id}-to-step-{self.step_id + self.video_length}.mp4"
+        self.video_path = os.path.join(self.video_folder, self.video_name)
         self._start_recording()
         self._capture_frame()
 
@@ -109,8 +112,6 @@ def _capture_frame(self) -> None:
         assert self.recording, "Cannot capture a frame, recording wasn't started."
 
         frame = self.env.render()
-        if isinstance(frame, list):
-            frame = frame[-1]
 
         if isinstance(frame, np.ndarray):
             self.recorded_frames.append(frame)
@@ -123,12 +124,12 @@ def _capture_frame(self) -> None:
     def close(self) -> None:
         """Closes the wrapper then the video recorder."""
         VecEnvWrapper.close(self)
-        if self.recording:
+        if self.recording:  # pragma: no cover
             self._stop_recording()
 
     def _start_recording(self) -> None:
         """Start a new recording. If it is already recording, stops the current recording before starting the new one."""
-        if self.recording:
+        if self.recording:  # pragma: no cover
             self._stop_recording()
 
         self.recording = True
@@ -137,7 +138,7 @@ def _stop_recording(self) -> None:
         """Stop current recording and saves the video."""
         assert self.recording, "_stop_recording was called, but no recording was started"
 
-        if len(self.recorded_frames) == 0:
+        if len(self.recorded_frames) == 0:  # pragma: no cover
             logger.warn("Ignored saving a video as there were zero frames to save.")
         else:
             from moviepy.video.io.ImageSequenceClip import ImageSequenceClip
@@ -150,5 +151,5 @@ def _stop_recording(self) -> None:
 
     def __del__(self) -> None:
         """Warn the user in case last video wasn't saved."""
-        if len(self.recorded_frames) > 0:
+        if len(self.recorded_frames) > 0:  # pragma: no cover
             logger.warn("Unable to save last video! Did you call close()?")

stable_baselines3/version.txt

@@ -1 +1 @@
-2.5.0a0
+2.5.0a1

tests/test_vec_envs.py

@@ -11,9 +11,17 @@
 import pytest
 from gymnasium import spaces
 
+from stable_baselines3 import PPO
 from stable_baselines3.common.env_util import make_vec_env
 from stable_baselines3.common.monitor import Monitor
-from stable_baselines3.common.vec_env import DummyVecEnv, SubprocVecEnv, VecFrameStack, VecNormalize
+from stable_baselines3.common.vec_env import DummyVecEnv, SubprocVecEnv, VecFrameStack, VecNormalize, VecVideoRecorder
+
+try:
+    import moviepy
+
+    have_moviepy = True
+except ImportError:
+    have_moviepy = False
 
 N_ENVS = 3
 VEC_ENV_CLASSES = [DummyVecEnv, SubprocVecEnv]
@@ -624,3 +632,37 @@ def test_render(vec_env_class):
     vec_env.render()
 
     vec_env.close()
+
+
+@pytest.mark.skipif(not have_moviepy, reason="moviepy is not installed")
+def test_video_recorder(tmp_path):
+    env_id = "CartPole-v1"
+    video_folder = str(tmp_path)
+
+    vec_env = make_vec_env(env_id, n_envs=1)
+
+    # Wrap to check unwrapping works
+    vec_env = VecNormalize(vec_env)
+
+    # Record the video starting at the first step
+    vec_env = VecVideoRecorder(
+        vec_env,
+        video_folder,
+        record_video_trigger=lambda x: x % 65 == 0,
+        video_length=10,
+        name_prefix=f"agent-{env_id}",
+    )
+
+    model = PPO("MlpPolicy", vec_env, n_steps=64, n_epochs=1, verbose=0)
+
+    model.learn(total_timesteps=128)
+
+    # print all videos in video_folder, should be multiple step 0-100, step 1024-1124
+    video_files = list(map(str, tmp_path.glob("*.mp4")))
+
+    # Clean up
+    vec_env.close()
+
+    assert len(video_files) == 2
+    assert "agent-CartPole-v1-step-65-to-step-75.mp4" in video_files[0]
+    assert "agent-CartPole-v1-step-0-to-step-10.mp4" in video_files[1]