add read gifs as video support

diffsynth/trainers/utils.py

@@ -154,7 +154,7 @@ class VideoDataset(torch.utils.data.Dataset):
         height_division_factor=16, width_division_factor=16,
         data_file_keys=("video",),
         image_file_extension=("jpg", "jpeg", "png", "webp"),
-        video_file_extension=("mp4", "avi", "mov", "wmv", "mkv", "flv", "webm"),
+        video_file_extension=("mp4", "avi", "mov", "wmv", "mkv", "flv", "webm", "gif"),
         repeat=1,
         args=None,
     ):
@@ -259,8 +259,41 @@ class VideoDataset(torch.utils.data.Dataset):
                 num_frames -= 1
         return num_frames
     
-
+    def _load_gif(self, file_path):
+        gif_img = Image.open(file_path)
+        frame_count = 0
+        delays, frames = [], []
+        while True:
+            delay = gif_img.info.get('duration', 100) # ms
+            delays.append(delay)
+            rgb_frame = gif_img.convert("RGB")   
+            croped_frame = self.crop_and_resize(rgb_frame, *self.get_height_width(rgb_frame))
+            frames.append(croped_frame)             
+            frame_count += 1
+            try:
+                gif_img.seek(frame_count)
+            except:
+                break
+        # delays canbe used to calculate framerates
+        # i guess it is better to sample images with stable interval,
+        # and using minimal_interval as the interval, 
+        # and framerate = 1000 / minimal_interval
+        if any((delays[0] != i) for i in delays):
+            minimal_interval = min([i for i in delays if i > 0])
+            # make a ((start,end),frameid) struct
+            start_end_idx_map = [((sum(delays[:i]), sum(delays[:i+1])), i) for i in range(len(delays))]
+            _frames = []
+            for i in range(sum(delays) // minimal_interval):
+                current_time = minimal_interval * i
+                for ((start, end), frame_idx) in start_end_idx_map:
+                    if start <= current_time < end:
+                        _frames.append(frames[frame_idx])
+            frames = _frames
+        return frames
+    
     def load_video(self, file_path):
+        if file_path.lower().endswith(".gif"):
+            return self._load_gif(file_path)
         reader = imageio.get_reader(file_path)
         num_frames = self.get_num_frames(reader)
         frames = []