Add C++ runtime for spleeter about source separation (#2242)

scripts/spleeter/unet.py

@@ -67,6 +67,14 @@ class UNet(torch.nn.Module):
         self.up7 = torch.nn.Conv2d(1, 2, kernel_size=4, dilation=2, padding=3)
 
     def forward(self, x):
+        """
+        Args:
+          x: (num_audio_channels, num_splits, 512, 1024)
+        Returns:
+          y: (num_audio_channels, num_splits, 512, 1024)
+        """
+        x = x.permute(1, 0, 2, 3)
+
         in_x = x
         # in_x is (3, 2, 512, 1024) = (T, 2, 512, 1024)
         x = torch.nn.functional.pad(x, (1, 2, 1, 2), "constant", 0)
@@ -147,4 +155,5 @@ class UNet(torch.nn.Module):
         up7 = self.up7(batch12)
         up7 = torch.sigmoid(up7)  # (3, 2, 512, 1024)
 
-        return up7 * in_x
+        ans = up7 * in_x
+        return ans.permute(1, 0, 2, 3)