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Fix batch decoding for Wan-Video-VAE #859

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Merged
Artiprocher merged 2 commits into from
Aug 29, 2025
Merged

Fix batch decoding for Wan-Video-VAE #859

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ac2e859
Fix batch decoding for Wan VAE.
krahets Aug 26, 2025
419d47c
Remove unnecessary newline in encode method
krahets Aug 26, 2025
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18 changes: 12 additions & 6 deletions diffsynth/models/wan_video_vae.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1216,7 +1216,6 @@ def single_decode(self, hidden_state, device):


def encode(self, videos, device, tiled=False, tile_size=(34, 34), tile_stride=(18, 16)):

videos = [video.to("cpu") for video in videos]
hidden_states = []
for video in videos:
Expand All @@ -1234,11 +1233,18 @@ def encode(self, videos, device, tiled=False, tile_size=(34, 34), tile_stride=(1


def decode(self, hidden_states, device, tiled=False, tile_size=(34, 34), tile_stride=(18, 16)):
if tiled:
video = self.tiled_decode(hidden_states, device, tile_size, tile_stride)
else:
video = self.single_decode(hidden_states, device)
return video
hidden_states = [hidden_state.to("cpu") for hidden_state in hidden_states]
videos = []
for hidden_state in hidden_states:
hidden_state = hidden_state.unsqueeze(0)
if tiled:
video = self.tiled_decode(hidden_state, device, tile_size, tile_stride)
else:
video = self.single_decode(hidden_state, device)
video = video.squeeze(0)
videos.append(video)
videos = torch.stack(videos)
return videos
Comment on lines +1236 to +1247
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@gemini-code-assist gemini-code-assist bot Aug 26, 2025

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medium

The implementation correctly fixes the batch decoding issue by iterating through the batch. However, the code can be made more readable and slightly more memory-efficient.

  1. The current implementation reassigns hidden_states and then uses hidden_state as a loop variable which is also reassigned inside the loop. This can be confusing. Using new variable names for clarity is better.
  2. It's slightly more memory-efficient to move each hidden_state to CPU inside the loop, rather than creating a new list of all hidden states on CPU at once.

Here is a suggested refactoring that addresses these points.

        videos = []
        for hs in hidden_states:
            hs_batch = hs.to("cpu").unsqueeze(0)
            if tiled:
                video = self.tiled_decode(hs_batch, device, tile_size, tile_stride)
            else:
                video = self.single_decode(hs_batch, device)
            videos.append(video.squeeze(0))
        return torch.stack(videos)



@staticmethod
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