Unify video metadata in VideoClips (#1527)

* Unify video metadata in VideoClips

* Bugfix

* Make tests a bit more robust

test/test_datasets_video_utils.py

@@ -59,7 +59,7 @@ class Tester(unittest.TestCase):
         self.assertTrue(r.equal(expected))
 
     @unittest.skipIf(not io.video._av_available(), "this test requires av")
-    @unittest.skipIf('win' in sys.platform, 'temporarily disabled on Windows')
+    @unittest.skipIf(sys.platform == 'win32', 'temporarily disabled on Windows')
     def test_video_clips(self):
         with get_list_of_videos(num_videos=3) as video_list:
             video_clips = VideoClips(video_list, 5, 5)
@@ -84,7 +84,7 @@ class Tester(unittest.TestCase):
                 self.assertEqual(clip_idx, c_idx)
 
     @unittest.skipIf(not io.video._av_available(), "this test requires av")
-    @unittest.skipIf('win' in sys.platform, 'temporarily disabled on Windows')
+    @unittest.skipIf(sys.platform == 'win32', 'temporarily disabled on Windows')
     def test_video_clips_custom_fps(self):
         with get_list_of_videos(num_videos=3, sizes=[12, 12, 12], fps=[3, 4, 6]) as video_list:
             num_frames = 4
@@ -94,6 +94,7 @@ class Tester(unittest.TestCase):
                     video, audio, info, video_idx = video_clips.get_clip(i)
                     self.assertEqual(video.shape[0], num_frames)
                     self.assertEqual(info["video_fps"], fps)
+                    self.assertEqual(info, {"video_fps": fps})
                     # TODO add tests checking that the content is right
 
     def test_compute_clips_for_video(self):

test/test_datasets_video_utils_opt.py

+import unittest
+from torchvision import set_video_backend
+import test_datasets_video_utils
+
+
+set_video_backend('video_reader')
+
+
+if __name__ == '__main__':
+    suite = unittest.TestLoader().loadTestsFromModule(test_datasets_video_utils)
+    unittest.TextTestRunner(verbosity=1).run(suite)

test/test_io.py

@@ -183,6 +183,7 @@ class Tester(unittest.TestCase):
 
             self.assertTrue(data.equal(lv))
             self.assertEqual(info["video_fps"], 5)
+            self.assertEqual(info, {"video_fps": 5})
 
     def test_read_timestamps_pts_unit_sec(self):
         with temp_video(10, 300, 300, 5) as (f_name, data):

torchvision/datasets/video_utils.py

@@ -5,6 +5,7 @@ import torch
 from torchvision.io import (
     _read_video_timestamps_from_file,
     _read_video_from_file,
+    _probe_video_from_file
 )
 from torchvision.io import read_video_timestamps, read_video
 
@@ -71,11 +72,11 @@ class VideoClips(object):
                  frame_rate=None, _precomputed_metadata=None, num_workers=0,
                  _video_width=0, _video_height=0, _video_min_dimension=0,
                  _audio_samples=0):
-        from torchvision import get_video_backend
 
         self.video_paths = video_paths
         self.num_workers = num_workers
-        self._backend = get_video_backend()
+
+        # these options are not valid for pyav backend
         self._video_width = _video_width
         self._video_height = _video_height
         self._video_min_dimension = _video_min_dimension
@@ -89,30 +90,23 @@ class VideoClips(object):
 
     def _compute_frame_pts(self):
         self.video_pts = []
-        if self._backend == "pyav":
         self.video_fps = []
-        else:
-            self.info = []
 
         # strategy: use a DataLoader to parallelize read_video_timestamps
         # so need to create a dummy dataset first
         class DS(object):
-            def __init__(self, x, _backend):
+            def __init__(self, x):
                 self.x = x
-                self._backend = _backend
 
             def __len__(self):
                 return len(self.x)
 
             def __getitem__(self, idx):
-                if self._backend == "pyav":
                 return read_video_timestamps(self.x[idx])
-                else:
-                    return _read_video_timestamps_from_file(self.x[idx])
 
         import torch.utils.data
         dl = torch.utils.data.DataLoader(
-            DS(self.video_paths, self._backend),
+            DS(self.video_paths),
             batch_size=16,
             num_workers=self.num_workers,
             collate_fn=lambda x: x)
@@ -120,56 +114,36 @@ class VideoClips(object):
         with tqdm(total=len(dl)) as pbar:
             for batch in dl:
                 pbar.update(1)
-                if self._backend == "pyav":
                 clips, fps = list(zip(*batch))
                 clips = [torch.as_tensor(c) for c in clips]
                 self.video_pts.extend(clips)
                 self.video_fps.extend(fps)
-                else:
-                    video_pts, _audio_pts, info = list(zip(*batch))
-                    video_pts = [torch.as_tensor(c) for c in video_pts]
-                    self.video_pts.extend(video_pts)
-                    self.info.extend(info)
 
     def _init_from_metadata(self, metadata):
         self.video_paths = metadata["video_paths"]
         assert len(self.video_paths) == len(metadata["video_pts"])
         self.video_pts = metadata["video_pts"]
-
-        if self._backend == "pyav":
         assert len(self.video_paths) == len(metadata["video_fps"])
         self.video_fps = metadata["video_fps"]
-        else:
-            assert len(self.video_paths) == len(metadata["info"])
-            self.info = metadata["info"]
 
     @property
     def metadata(self):
         _metadata = {
             "video_paths": self.video_paths,
             "video_pts": self.video_pts,
+            "video_fps": self.video_fps
         }
-        if self._backend == "pyav":
-            _metadata.update({"video_fps": self.video_fps})
-        else:
-            _metadata.update({"info": self.info})
         return _metadata
 
     def subset(self, indices):
         video_paths = [self.video_paths[i] for i in indices]
         video_pts = [self.video_pts[i] for i in indices]
-        if self._backend == "pyav":
         video_fps = [self.video_fps[i] for i in indices]
-        else:
-            info = [self.info[i] for i in indices]
         metadata = {
             "video_paths": video_paths,
             "video_pts": video_pts,
+            "video_fps": video_fps
         }
-        if self._backend == "pyav":
-            metadata.update({"video_fps": video_fps})
-        else:
-            metadata.update({"info": info})
         return type(self)(video_paths, self.num_frames, self.step, self.frame_rate,
                           _precomputed_metadata=metadata, num_workers=self.num_workers,
                           _video_width=self._video_width,
@@ -212,22 +186,10 @@ class VideoClips(object):
         self.frame_rate = frame_rate
         self.clips = []
         self.resampling_idxs = []
-        if self._backend == "pyav":
         for video_pts, fps in zip(self.video_pts, self.video_fps):
             clips, idxs = self.compute_clips_for_video(video_pts, num_frames, step, fps, frame_rate)
             self.clips.append(clips)
             self.resampling_idxs.append(idxs)
-        else:
-            for video_pts, info in zip(self.video_pts, self.info):
-                if "video_fps" in info:
-                    clips, idxs = self.compute_clips_for_video(
-                        video_pts, num_frames, step, info["video_fps"], frame_rate)
-                    self.clips.append(clips)
-                    self.resampling_idxs.append(idxs)
-                else:
-                    # properly handle the cases where video decoding fails
-                    self.clips.append(torch.zeros(0, num_frames, dtype=torch.int64))
-                    self.resampling_idxs.append(torch.zeros(0, dtype=torch.int64))
         clip_lengths = torch.as_tensor([len(v) for v in self.clips])
         self.cumulative_sizes = clip_lengths.cumsum(0).tolist()
 
@@ -287,12 +249,28 @@ class VideoClips(object):
         video_path = self.video_paths[video_idx]
         clip_pts = self.clips[video_idx][clip_idx]
 
-        if self._backend == "pyav":
+        from torchvision import get_video_backend
+        backend = get_video_backend()
+
+        if backend == "pyav":
+            # check for invalid options
+            if self._video_width != 0:
+                raise ValueError("pyav backend doesn't support _video_width != 0")
+            if self._video_height != 0:
+                raise ValueError("pyav backend doesn't support _video_height != 0")
+            if self._video_min_dimension != 0:
+                raise ValueError("pyav backend doesn't support _video_min_dimension != 0")
+            if self._audio_samples != 0:
+                raise ValueError("pyav backend doesn't support _audio_samples != 0")
+
+        if backend == "pyav":
             start_pts = clip_pts[0].item()
             end_pts = clip_pts[-1].item()
             video, audio, info = read_video(video_path, start_pts, end_pts)
         else:
-            info = self.info[video_idx]
+            info = _probe_video_from_file(video_path)
+            video_fps = info["video_fps"]
+            audio_fps = None
 
             video_start_pts = clip_pts[0].item()
             video_end_pts = clip_pts[-1].item()
@@ -313,6 +291,7 @@ class VideoClips(object):
                     info["audio_timebase"],
                     math.ceil,
                 )
+                audio_fps = info["audio_sample_rate"]
             video, audio, info = _read_video_from_file(
                 video_path,
                 video_width=self._video_width,
@@ -324,6 +303,11 @@ class VideoClips(object):
                 audio_pts_range=(audio_start_pts, audio_end_pts),
                 audio_timebase=audio_timebase,
             )
+
+            info = {"video_fps": video_fps}
+            if audio_fps is not None:
+                info["audio_fps"] = audio_fps
+
         if self.frame_rate is not None:
             resampling_idx = self.resampling_idxs[video_idx][clip_idx]
             if isinstance(resampling_idx, torch.Tensor):

torchvision/io/_video_opt.py

@@ -383,7 +383,7 @@ def _read_video(filename, start_pts=0, end_pts=None, pts_unit='pts'):
         audio_timebase = info['audio_timebase']
         audio_pts_range = get_pts(audio_timebase)
 
-    return _read_video_from_file(
+    vframes, aframes, info = _read_video_from_file(
         filename,
         read_video_stream=True,
         video_pts_range=video_pts_range,
@@ -392,6 +392,13 @@ def _read_video(filename, start_pts=0, end_pts=None, pts_unit='pts'):
         audio_pts_range=audio_pts_range,
         audio_timebase=audio_timebase,
     )
+    _info = {}
+    if has_video:
+        _info['video_fps'] = info['video_fps']
+    if has_audio:
+        _info['audio_fps'] = info['audio_sample_rate']
+
+    return vframes, aframes, _info
 
 
 def _read_video_timestamps(filename, pts_unit='pts'):