diff --git a/sat/data_video.py b/sat/data_video.py
index 3783340..8f2ef23 100644
--- a/sat/data_video.py
+++ b/sat/data_video.py
@@ -378,8 +378,9 @@ class SFTDataset(Dataset):
                         num_frames = max_num_frames
                         start = int(skip_frms_num)
                         end = int(start + num_frames / fps * actual_fps)
-                        indices = np.arange(start, end, (end - start) / num_frames).astype(int)
-                        temp_frms = vr.get_batch(np.arange(start, end))
+                        end_safty = min(int(start + num_frames / fps * actual_fps), int(ori_vlen))
+                        indices = np.arange(start, end, (end - start) // num_frames).astype(int)
+                        temp_frms = vr.get_batch(np.arange(start, end_safty))
                         assert temp_frms is not None
                         tensor_frms = torch.from_numpy(temp_frms) if type(temp_frms) is not torch.Tensor else temp_frms
                         tensor_frms = tensor_frms[torch.tensor((indices - start).tolist())]
@@ -388,7 +389,7 @@ class SFTDataset(Dataset):
                             num_frames = max_num_frames
                             start = int(skip_frms_num)
                             end = int(ori_vlen - skip_frms_num)
-                            indices = np.arange(start, end, (end - start) / num_frames).astype(int)
+                            indices = np.arange(start, end, (end - start) // num_frames).astype(int)
                             temp_frms = vr.get_batch(np.arange(start, end))
                             assert temp_frms is not None
                             tensor_frms = (