diff --git a/chatsim/agents/background_rendering_agent.py b/chatsim/agents/background_rendering_agent.py
index 78051ed..331161b 100644
--- a/chatsim/agents/background_rendering_agent.py
+++ b/chatsim/agents/background_rendering_agent.py
@@ -43,6 +43,10 @@ def func_render_background(self, scene):
             poses_render = scene.current_extrinsics[:, :3, :]
             np.save(os.path.join(self.nerf_data_dir, 'poses_render.npy'), poses_render)
 
+            # remove previous rendered images
+            if os.path.exists(self.nerf_novel_view_dir) and len(os.listdir(self.nerf_novel_view_dir)) > 0:
+                os.system(f"rm -r {self.nerf_novel_view_dir}/*")
+
             current_dir = os.getcwd()
             os.chdir(self.f2nerf_dir) # do not generate intermediate file at root directory
             render_command = f'python scripts/run.py \
diff --git a/chatsim/agents/utils.py b/chatsim/agents/utils.py
index 821af03..16c94db 100644
--- a/chatsim/agents/utils.py
+++ b/chatsim/agents/utils.py
@@ -10,6 +10,7 @@
 import imageio.v2 as imageio
 import collections
 from termcolor import colored
+from tqdm import tqdm
 
 class Struct:
     def __init__(self, **entries):
@@ -33,15 +34,10 @@ def generate_video(scene, prompt):
     filename = prompt.replace(' ', '_')[:40]
     fps = scene.fps
     print(colored("[Compositing video]", 'blue', attrs=['bold']), "start...")
-    # save to gif
-    imageio.mimsave(os.path.join(video_output_path, f"{filename}.gif"), 
-                    scene.final_video_frames, 
-                    fps=fps
-    )
-    # save to mp4
+
     writer = imageio.get_writer(os.path.join(video_output_path, f"{filename}.mp4"), 
                                 fps=fps)
-    for frame in scene.final_video_frames:
+    for frame in tqdm(scene.final_video_frames):
         writer.append_data(frame)
     writer.close()
     # save frames to folder
diff --git a/chatsim/background/inpainting/latent-diffusion/ldm/models/diffusion/ddpm.py b/chatsim/background/inpainting/latent-diffusion/ldm/models/diffusion/ddpm.py
index ef0990e..e4c6cb1 100644
--- a/chatsim/background/inpainting/latent-diffusion/ldm/models/diffusion/ddpm.py
+++ b/chatsim/background/inpainting/latent-diffusion/ldm/models/diffusion/ddpm.py
@@ -16,7 +16,10 @@
 from functools import partial
 from tqdm import tqdm
 from torchvision.utils import make_grid
-from pytorch_lightning.utilities.rank_zero import rank_zero_only
+try:
+    from pytorch_lightning.utilities.distributed import rank_zero_only
+except ImportError:
+    from pytorch_lightning.utilities.rank_zero import rank_zero_only
 
 from ldm.util import log_txt_as_img, exists, default, ismap, isimage, mean_flat, count_params, instantiate_from_config
 from ldm.modules.ema import LitEma
diff --git a/chatsim/background/inpainting/latent-diffusion/main.py b/chatsim/background/inpainting/latent-diffusion/main.py
index e8e18c1..99f120e 100644
--- a/chatsim/background/inpainting/latent-diffusion/main.py
+++ b/chatsim/background/inpainting/latent-diffusion/main.py
@@ -14,7 +14,10 @@
 from pytorch_lightning import seed_everything
 from pytorch_lightning.trainer import Trainer
 from pytorch_lightning.callbacks import ModelCheckpoint, Callback, LearningRateMonitor
-from pytorch_lightning.utilities.distributed import rank_zero_only
+try: # previous requirements.txt
+    from pytorch_lightning.utilities.distributed import rank_zero_only
+except ImportError: # new requirements.txt
+    from pytorch_lightning.utilities.rank_zero import rank_zero_only
 from pytorch_lightning.utilities import rank_zero_info
 
 from ldm.data.base import Txt2ImgIterableBaseDataset