From af4d412e67bb72af64bf223385acff7f67ed3220 Mon Sep 17 00:00:00 2001
From: kijai <40791699+kijai@users.noreply.github.com>
Date: Wed, 26 Nov 2025 18:14:54 +0200
Subject: [PATCH] Chunk attention map calculation for multiple speakers to
 reduce peak VRAM usage

---
 comfy/ldm/wan/model.py           |  8 +++---
 comfy/ldm/wan/model_multitalk.py | 43 +++++++++++++++++++++-----------
 comfy_extras/nodes_wan.py        |  4 +--
 3 files changed, 35 insertions(+), 20 deletions(-)

diff --git a/comfy/ldm/wan/model.py b/comfy/ldm/wan/model.py
index a34df1dbd..23feb9a7b 100644
--- a/comfy/ldm/wan/model.py
+++ b/comfy/ldm/wan/model.py
@@ -88,8 +88,8 @@ class WanSelfAttention(nn.Module):
             transformer_options=transformer_options,
         )
 
-        if "self_attn" in patches:
-            for p in patches["self_attn"]:
+        if "attn1_patch" in patches:
+            for p in patches["attn1_patch"]:
                 x = p({"x": x, "q": q, "k": k, "transformer_options": transformer_options})
 
         x = self.o(x)
@@ -251,8 +251,8 @@ class WanAttentionBlock(nn.Module):
         # cross-attention & ffn
         x = x + self.cross_attn(self.norm3(x), context, context_img_len=context_img_len, transformer_options=transformer_options)
 
-        if "cross_attn" in patches:
-            for p in patches["cross_attn"]:
+        if "attn2_patch" in patches:
+            for p in patches["attn2_patch"]:
                 x = p({"x": x, "transformer_options": transformer_options})
 
         y = self.ffn(torch.addcmul(repeat_e(e[3], x), self.norm2(x), 1 + repeat_e(e[4], x)))
diff --git a/comfy/ldm/wan/model_multitalk.py b/comfy/ldm/wan/model_multitalk.py
index a651618c8..7e7dda7d5 100644
--- a/comfy/ldm/wan/model_multitalk.py
+++ b/comfy/ldm/wan/model_multitalk.py
@@ -4,27 +4,42 @@ import comfy
 from comfy.ldm.modules.attention import optimized_attention
 
 
-def calculate_x_ref_attn_map(visual_q, ref_k, ref_target_masks):
+def calculate_x_ref_attn_map(visual_q, ref_k, ref_target_masks, split_num=8):
     scale = 1.0 / visual_q.shape[-1] ** 0.5
     visual_q = visual_q.transpose(1, 2) * scale
 
-    attn = visual_q @ ref_k.permute(0, 2, 3, 1).to(visual_q)
-
-    x_ref_attn_map_source = attn.softmax(-1).to(visual_q.dtype) # B, H, x_seqlens, ref_seqlens
-    del attn
+    B, H, x_seqlens, K = visual_q.shape
 
     x_ref_attn_maps = []
-
     for class_idx, ref_target_mask in enumerate(ref_target_masks):
-        ref_target_mask = ref_target_mask.view(1, 1, 1, *ref_target_mask.shape)
-        x_ref_attnmap = x_ref_attn_map_source * ref_target_mask
-        x_ref_attnmap = x_ref_attnmap.sum(-1) / ref_target_mask.sum() # B, H, x_seqlens, ref_seqlens --> B, H, x_seqlens
-        x_ref_attnmap = x_ref_attnmap.transpose(1, 2) # B, x_seqlens, H
-        x_ref_attnmap = x_ref_attnmap.mean(-1) # B, x_seqlens
+        ref_target_mask = ref_target_mask.view(1, 1, 1, -1)
+
+        x_ref_attnmap = torch.zeros(B, H, x_seqlens, device=visual_q.device, dtype=visual_q.dtype)
+        chunk_size = min(max(x_seqlens // split_num, 1), x_seqlens)
+        
+        for i in range(0, x_seqlens, chunk_size):
+            end_i = min(i + chunk_size, x_seqlens)
+            
+            attn_chunk = visual_q[:, :, i:end_i] @ ref_k.permute(0, 2, 3, 1)  # B, H, chunk, ref_seqlens
+            
+            # Apply softmax
+            attn_max = attn_chunk.max(dim=-1, keepdim=True).values
+            attn_chunk = (attn_chunk - attn_max).exp()
+            attn_sum = attn_chunk.sum(dim=-1, keepdim=True)
+            attn_chunk = attn_chunk / (attn_sum + 1e-8)
+            
+            # Apply mask and sum
+            masked_attn = attn_chunk * ref_target_mask
+            x_ref_attnmap[:, :, i:end_i] = masked_attn.sum(-1) / (ref_target_mask.sum() + 1e-8)
+            
+            del attn_chunk, masked_attn
+        
+        # Average across heads
+        x_ref_attnmap = x_ref_attnmap.mean(dim=1)  # B, x_seqlens
         x_ref_attn_maps.append(x_ref_attnmap)
-
-    del x_ref_attn_map_source
-
+    
+    del visual_q, ref_k
+    
     return torch.cat(x_ref_attn_maps, dim=0)
 
 def get_attn_map_with_target(visual_q, ref_k, shape, ref_target_masks=None, split_num=2):
diff --git a/comfy_extras/nodes_wan.py b/comfy_extras/nodes_wan.py
index 409025121..8e0f8287b 100644
--- a/comfy_extras/nodes_wan.py
+++ b/comfy_extras/nodes_wan.py
@@ -1429,9 +1429,9 @@ class WanInfiniteTalkToVideo(io.ComfyNode):
                 is_extend=previous_frames is not None,
             ))
         # add cross-attention patch
-        model_patched.set_model_patch(MultiTalkCrossAttnPatch(model_patch, audio_scale), "cross_attn")
+        model_patched.set_model_patch(MultiTalkCrossAttnPatch(model_patch, audio_scale), "attn2_patch")
         if token_ref_target_masks is not None:
-            model_patched.set_model_patch(MultiTalkGetAttnMapPatch(token_ref_target_masks), "self_attn")
+            model_patched.set_model_patch(MultiTalkGetAttnMapPatch(token_ref_target_masks), "attn1_patch")
 
         out_latent = {}
         out_latent["samples"] = latent