@@ -266,14 +266,15 @@ def __repr__(self):
266266
267267
268268@TRANSFORMS .register_module ()
269- class UniformSampleFrames (BaseTransform ):
270- """Uniformly sample frames from the video.
269+ class UniformSample (BaseTransform ):
270+ """Uniformly sample frames from the video. Currently used for Something-
271+ Something V2 dataset. Modified from
272+ https://github.com/facebookresearch/SlowFast/blob/64a
273+ bcc90ccfdcbb11cf91d6e525bed60e92a8796/slowfast/datasets/ssv2.py#L159.
271274
272275 To sample an n-frame clip from the video. UniformSampleFrames basically
273276 divides the video into n segments of equal length and randomly samples one
274- frame from each segment. To make the testing results reproducible, a
275- random seed is set during testing, to make the sampling results
276- deterministic.
277+ frame from each segment.
277278
278279 Required keys:
279280
@@ -292,113 +293,23 @@ class UniformSampleFrames(BaseTransform):
292293 num_clips (int): Number of clips to be sampled. Default: 1.
293294 test_mode (bool): Store True when building test or validation dataset.
294295 Default: False.
295- seed (int): The random seed used during test time. Default: 255.
296- out_of_bound_opt (str): The way to deal with out of bounds frame
297- indexes. Available options are 'loop', 'repeat_frame'.
298- Default: 'loop'.
299296 """
300297
301298 def __init__ (self ,
302299 clip_len : int ,
303300 num_clips : int = 1 ,
304- test_mode : bool = False ,
305- seed : int = 255 ,
306- out_of_bound_opt : str = 'loop' ) -> None :
301+ test_mode : bool = False ) -> None :
307302
308303 self .clip_len = clip_len
309304 self .num_clips = num_clips
310305 self .test_mode = test_mode
311- self .seed = seed
312- self .out_of_bound_opt = out_of_bound_opt
313- assert self .out_of_bound_opt in ['loop' , 'repeat_frame' ]
314-
315- def _get_train_clips (self , num_frames : int ):
316- """Uniformly sample indices for training clips.
317-
318- Args:
319- num_frames (int): The number of frames.
320- """
321-
322- assert self .num_clips == 1
323- if num_frames < self .clip_len :
324- start = np .random .randint (0 , num_frames )
325- inds = np .arange (start , start + self .clip_len )
326- elif self .clip_len <= num_frames < 2 * self .clip_len :
327- basic = np .arange (self .clip_len )
328- inds = np .random .choice (
329- self .clip_len + 1 , num_frames - self .clip_len , replace = False )
330- offset = np .zeros (self .clip_len + 1 , dtype = np .int32 )
331- offset [inds ] = 1
332- offset = np .cumsum (offset )
333- inds = basic + offset [:- 1 ]
334- else :
335- bids = np .array ([
336- i * num_frames // self .clip_len
337- for i in range (self .clip_len + 1 )
338- ])
339- bsize = np .diff (bids )
340- bst = bids [:self .clip_len ]
341- offset = np .random .randint (bsize )
342- inds = bst + offset
343- return inds
344-
345- def _get_test_clips (self , num_frames : int ):
346- """Uniformly sample indices for testing clips.
347306
348- Args:
349- num_frames (int): The number of frames.
350- """
351-
352- np .random .seed (self .seed )
353- if num_frames < self .clip_len :
354- # Then we use a simple strategy
355- if num_frames < self .num_clips :
356- start_inds = list (range (self .num_clips ))
357- else :
358- start_inds = [
359- i * num_frames // self .num_clips
360- for i in range (self .num_clips )
361- ]
362- inds = np .concatenate (
363- [np .arange (i , i + self .clip_len ) for i in start_inds ])
364- elif self .clip_len <= num_frames < self .clip_len * 2 :
365- all_inds = []
366- for i in range (self .num_clips ):
367- basic = np .arange (self .clip_len )
368- inds = np .random .choice (
369- self .clip_len + 1 ,
370- num_frames - self .clip_len ,
371- replace = False )
372- offset = np .zeros (self .clip_len + 1 , dtype = np .int32 )
373- offset [inds ] = 1
374- offset = np .cumsum (offset )
375- inds = basic + offset [:- 1 ]
376- all_inds .append (inds )
377- inds = np .concatenate (all_inds )
378- else :
379- bids = np .array ([
380- i * num_frames // self .clip_len
381- for i in range (self .clip_len + 1 )
382- ])
383- bsize = np .diff (bids )
384- bst = bids [:self .clip_len ]
385- all_inds = []
386- for i in range (self .num_clips ):
387- offset = np .random .randint (bsize )
388- all_inds .append (bst + offset )
389- inds = np .concatenate (all_inds )
390- return inds
391-
392- def _get_repeat_sample_clips (self , num_frames : int ) -> np .array :
393- """Repeat sample when video is shorter than clip_len Modified from
394- https://github.com/facebookresearch/SlowFast/blob/64ab
395- cc90ccfdcbb11cf91d6e525bed60e92a8796/slowfast/datasets/ssv2.py#L159.
396-
397- When video frames is shorter than target clip len, this strategy would
398- repeat sample frame, rather than loop sample in 'loop' mode.
399- In test mode, this strategy would sample the middle frame of each
400- segment, rather than set a random seed, and therefore only support
401- sample 1 clip.
307+ def _get_sample_clips (self , num_frames : int ) -> np .array :
308+ """When video frames is shorter than target clip len, this strategy
309+ would repeat sample frame, rather than loop sample in 'loop' mode. In
310+ test mode, this strategy would sample the middle frame of each segment,
311+ rather than set a random seed, and therefore only support sample 1
312+ clip.
402313
403314 Args:
404315 num_frames (int): Total number of frame in the video.
@@ -421,17 +332,7 @@ def _get_repeat_sample_clips(self, num_frames: int) -> np.array:
421332 def transform (self , results : dict ):
422333 num_frames = results ['total_frames' ]
423334
424- if self .out_of_bound_opt == 'loop' :
425- if self .test_mode :
426- inds = self ._get_test_clips (num_frames )
427- else :
428- inds = self ._get_train_clips (num_frames )
429- inds = np .mod (inds , num_frames )
430- elif self .out_of_bound_opt == 'repeat_frame' :
431- inds = self ._get_repeat_sample_clips (num_frames )
432- else :
433- raise ValueError ('Illegal out_of_bound option.' )
434-
335+ inds = self ._get_sample_clips (num_frames )
435336 start_index = results ['start_index' ]
436337 inds = inds + start_index
437338
@@ -445,8 +346,7 @@ def __repr__(self):
445346 repr_str = (f'{ self .__class__ .__name__ }
446347 f'clip_len={ self .clip_len }
447348 f'num_clips={ self .num_clips }
448- f'test_mode={ self .test_mode }
449- f'seed={ self .seed } )
349+ f'test_mode={ self .test_mode } )
450350 return repr_str
451351
452352
0 commit comments