[fbsync] Fix int/float typing in video_utils.py (#8234)

Summary: Co-authored-by: Nicolas Hug <nh.nicolas.hug@gmail.com>

Reviewed By: vmoens

Differential Revision: D55062804

fbshipit-source-id: a880482450d6275597bec500648ff1e085b65a39

torchvision/datasets/video_utils.py

@@ -89,7 +89,7 @@ class VideoClips:
         video_paths (List[str]): paths to the video files
         clip_length_in_frames (int): size of a clip in number of frames
         frames_between_clips (int): step (in frames) between each clip
-        frame_rate (int, optional): if specified, it will resample the video
+        frame_rate (float, optional): if specified, it will resample the video
             so that it has `frame_rate`, and then the clips will be defined
             on the resampled video
         num_workers (int): how many subprocesses to use for data loading.
@@ -102,7 +102,7 @@ def __init__(
         video_paths: List[str],
         clip_length_in_frames: int = 16,
         frames_between_clips: int = 1,
-        frame_rate: Optional[int] = None,
+        frame_rate: Optional[float] = None,
         _precomputed_metadata: Optional[Dict[str, Any]] = None,
         num_workers: int = 0,
         _video_width: int = 0,
@@ -136,7 +136,7 @@ def __init__(
 
     def _compute_frame_pts(self) -> None:
         self.video_pts = []  # len = num_videos. Each entry is a tensor of shape (num_frames_in_video,)
-        self.video_fps: List[int] = []  # len = num_videos
+        self.video_fps: List[float] = []  # len = num_videos
 
         # strategy: use a DataLoader to parallelize read_video_timestamps
         # so need to create a dummy dataset first
@@ -203,15 +203,15 @@ def subset(self, indices: List[int]) -> "VideoClips":
 
     @staticmethod
     def compute_clips_for_video(
-        video_pts: torch.Tensor, num_frames: int, step: int, fps: int, frame_rate: Optional[int] = None
+        video_pts: torch.Tensor, num_frames: int, step: int, fps: Optional[float], frame_rate: Optional[float] = None
     ) -> Tuple[torch.Tensor, Union[List[slice], torch.Tensor]]:
         if fps is None:
             # if for some reason the video doesn't have fps (because doesn't have a video stream)
             # set the fps to 1. The value doesn't matter, because video_pts is empty anyway
             fps = 1
         if frame_rate is None:
             frame_rate = fps
-        total_frames = len(video_pts) * (float(frame_rate) / fps)
+        total_frames = len(video_pts) * frame_rate / fps
         _idxs = VideoClips._resample_video_idx(int(math.floor(total_frames)), fps, frame_rate)
         video_pts = video_pts[_idxs]
         clips = unfold(video_pts, num_frames, step)
@@ -227,7 +227,7 @@ def compute_clips_for_video(
             idxs = unfold(_idxs, num_frames, step)
         return clips, idxs
 
-    def compute_clips(self, num_frames: int, step: int, frame_rate: Optional[int] = None) -> None:
+    def compute_clips(self, num_frames: int, step: int, frame_rate: Optional[float] = None) -> None:
         """
         Compute all consecutive sequences of clips from video_pts.
         Always returns clips of size `num_frames`, meaning that the
@@ -275,8 +275,8 @@ def get_clip_location(self, idx: int) -> Tuple[int, int]:
         return video_idx, clip_idx
 
     @staticmethod
-    def _resample_video_idx(num_frames: int, original_fps: int, new_fps: int) -> Union[slice, torch.Tensor]:
-        step = float(original_fps) / new_fps
+    def _resample_video_idx(num_frames: int, original_fps: float, new_fps: float) -> Union[slice, torch.Tensor]:
+        step = original_fps / new_fps
         if step.is_integer():
             # optimization: if step is integer, don't need to perform
             # advanced indexing