Add Sign Language detection model by Google

openhands/models/detection/lstm.py

@@ -0,0 +1,21 @@
+import torch
+import torch.nn as nn
+
+# Paper: https://arxiv.org/abs/2008.04637
+# Models ported from: https://github.com/google-research/google-research/tree/master/sign_language_detection
+
+class SignDetectionLSTM(nn.Module):
+    def __init__(self, input_dim=25, input_dropout = 0.5, encoder_layers = 1, hidden_size = 2**6, encoder_bidirectional = False):
+        super(SignDetectionLSTM, self).__init__()
+        self.input_dropout = nn.Dropout(p=input_dropout)
+        self.lstm = nn.LSTM(input_dim, hidden_size, encoder_layers, bidirectional=encoder_bidirectional, batch_first=True)
+        self.linear = nn.Linear(hidden_size, 2)
+
+    def forward(self, x, hidden=None):
+        # input.shape = [batch_size, seq_length, input_dim]
+        x = self.input_dropout(x)
+        lstm_out, self.hidden = self.lstm(input, hidden)
+        # shape = [batch_size, out_dim]
+        y_pred = self.linear(self.dropout(lstm_out[:,-1,:]))
+        return y_pred
+