From 8dab6d184a034ca86eafa644ea0d2100aadfe27d Mon Sep 17 00:00:00 2001
From: jmwang66 <wangjiaming.wjm@alibaba-inc.com>
Date: 星期二, 09 五月 2023 10:58:33 +0800
Subject: [PATCH] Merge pull request #473 from alibaba-damo-academy/dev_smohan

---
 funasr/modules/embedding.py |   90 +++++++++++++++++++++++++++++++++++++++-----
 1 files changed, 79 insertions(+), 11 deletions(-)

diff --git a/funasr/modules/embedding.py b/funasr/modules/embedding.py
index 4b292a7..aaac80a 100644
--- a/funasr/modules/embedding.py
+++ b/funasr/modules/embedding.py
@@ -425,19 +425,87 @@
         return encoding.type(dtype)
 
     def forward(self, x, cache=None):
-        start_idx = 0
-        pad_left = 0
-        pad_right = 0
         batch_size, timesteps, input_dim = x.size()
+        start_idx = 0
         if cache is not None:
             start_idx = cache["start_idx"]
-            pad_left = cache["left"]
-            pad_right = cache["right"]
+            cache["start_idx"] += timesteps
         positions = torch.arange(1, timesteps+start_idx+1)[None, :]
         position_encoding = self.encode(positions, input_dim, x.dtype).to(x.device)
-        outputs = x + position_encoding[:, start_idx: start_idx + timesteps]
-        outputs = outputs.transpose(1, 2)
-        outputs = F.pad(outputs, (pad_left, pad_right))
-        outputs = outputs.transpose(1, 2)
-        return outputs
-       
+        return x + position_encoding[:, start_idx: start_idx + timesteps]
+
+class StreamingRelPositionalEncoding(torch.nn.Module):
+    """Relative positional encoding.
+    Args:
+        size: Module size.
+        max_len: Maximum input length.
+        dropout_rate: Dropout rate.
+    """
+
+    def __init__(
+        self, size: int, dropout_rate: float = 0.0, max_len: int = 5000
+    ) -> None:
+        """Construct a RelativePositionalEncoding object."""
+        super().__init__()
+
+        self.size = size
+
+        self.pe = None
+        self.dropout = torch.nn.Dropout(p=dropout_rate)
+
+        self.extend_pe(torch.tensor(0.0).expand(1, max_len))
+        self._register_load_state_dict_pre_hook(_pre_hook)
+
+    def extend_pe(self, x: torch.Tensor, left_context: int = 0) -> None:
+        """Reset positional encoding.
+        Args:
+            x: Input sequences. (B, T, ?)
+            left_context: Number of frames in left context.
+        """
+        time1 = x.size(1) + left_context
+
+        if self.pe is not None:
+            if self.pe.size(1) >= time1 * 2 - 1:
+                if self.pe.dtype != x.dtype or self.pe.device != x.device:
+                    self.pe = self.pe.to(device=x.device, dtype=x.dtype)
+                return
+
+        pe_positive = torch.zeros(time1, self.size)
+        pe_negative = torch.zeros(time1, self.size)
+
+        position = torch.arange(0, time1, dtype=torch.float32).unsqueeze(1)
+        div_term = torch.exp(
+            torch.arange(0, self.size, 2, dtype=torch.float32)
+            * -(math.log(10000.0) / self.size)
+        )
+
+        pe_positive[:, 0::2] = torch.sin(position * div_term)
+        pe_positive[:, 1::2] = torch.cos(position * div_term)
+        pe_positive = torch.flip(pe_positive, [0]).unsqueeze(0)
+
+        pe_negative[:, 0::2] = torch.sin(-1 * position * div_term)
+        pe_negative[:, 1::2] = torch.cos(-1 * position * div_term)
+        pe_negative = pe_negative[1:].unsqueeze(0)
+
+        self.pe = torch.cat([pe_positive, pe_negative], dim=1).to(
+            dtype=x.dtype, device=x.device
+        )
+
+    def forward(self, x: torch.Tensor, left_context: int = 0) -> torch.Tensor:
+        """Compute positional encoding.
+        Args:
+            x: Input sequences. (B, T, ?)
+            left_context: Number of frames in left context.
+        Returns:
+            pos_enc: Positional embedding sequences. (B, 2 * (T - 1), ?)
+        """
+        self.extend_pe(x, left_context=left_context)
+
+        time1 = x.size(1) + left_context
+
+        pos_enc = self.pe[
+            :, self.pe.size(1) // 2 - time1 + 1 : self.pe.size(1) // 2 + x.size(1)
+        ]
+        pos_enc = self.dropout(pos_enc)
+
+        return pos_enc

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