File size: 21,416 Bytes
8e8cd3e
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
"""
modified from https://github.com/speechbrain/speechbrain/blob/develop/speechbrain/lobes/models/dual_path.py
#Author: Shengkui Zhao

"""

import math
import torch
import torch.nn as nn
import torch.nn.functional as F
import copy
from models.mossformer2_ss.mossformer2_block import ScaledSinuEmbedding, MossformerBlock_GFSMN, MossformerBlock


EPS = 1e-8


class GlobalLayerNorm(nn.Module):
    """Calculate Global Layer Normalization.

    Arguments
    ---------
       dim : (int or list or torch.Size)
           Input shape from an expected input of size.
       eps : float
           A value added to the denominator for numerical stability.
       elementwise_affine : bool
          A boolean value that when set to True,
          this module has learnable per-element affine parameters
          initialized to ones (for weights) and zeros (for biases).

    Example
    -------
    >>> x = torch.randn(5, 10, 20)
    >>> GLN = GlobalLayerNorm(10, 3)
    >>> x_norm = GLN(x)
    """

    def __init__(self, dim, shape, eps=1e-8, elementwise_affine=True):
        super(GlobalLayerNorm, self).__init__()
        self.dim = dim
        self.eps = eps
        self.elementwise_affine = elementwise_affine

        if self.elementwise_affine:
            if shape == 3:
                self.weight = nn.Parameter(torch.ones(self.dim, 1))
                self.bias = nn.Parameter(torch.zeros(self.dim, 1))
            if shape == 4:
                self.weight = nn.Parameter(torch.ones(self.dim, 1, 1))
                self.bias = nn.Parameter(torch.zeros(self.dim, 1, 1))
        else:
            self.register_parameter("weight", None)
            self.register_parameter("bias", None)

    def forward(self, x):
        """Returns the normalized tensor.

        Arguments
        ---------
        x : torch.Tensor
            Tensor of size [N, C, K, S] or [N, C, L].
        """
        # x = N x C x K x S or N x C x L
        # N x 1 x 1
        # cln: mean,var N x 1 x K x S
        # gln: mean,var N x 1 x 1
        if x.dim() == 3:
            mean = torch.mean(x, (1, 2), keepdim=True)
            var = torch.mean((x - mean) ** 2, (1, 2), keepdim=True)
            if self.elementwise_affine:
                x = (
                    self.weight * (x - mean) / torch.sqrt(var + self.eps)
                    + self.bias
                )
            else:
                x = (x - mean) / torch.sqrt(var + self.eps)

        if x.dim() == 4:
            mean = torch.mean(x, (1, 2, 3), keepdim=True)
            var = torch.mean((x - mean) ** 2, (1, 2, 3), keepdim=True)
            if self.elementwise_affine:
                x = (
                    self.weight * (x - mean) / torch.sqrt(var + self.eps)
                    + self.bias
                )
            else:
                x = (x - mean) / torch.sqrt(var + self.eps)
        return x


class CumulativeLayerNorm(nn.LayerNorm):
    """Calculate Cumulative Layer Normalization.

       Arguments
       ---------
       dim : int
        Dimension that you want to normalize.
       elementwise_affine : True
        Learnable per-element affine parameters.

    Example
    -------
    >>> x = torch.randn(5, 10, 20)
    >>> CLN = CumulativeLayerNorm(10)
    >>> x_norm = CLN(x)
    """

    def __init__(self, dim, elementwise_affine=True):
        super(CumulativeLayerNorm, self).__init__(
            dim, elementwise_affine=elementwise_affine, eps=1e-8
        )

    def forward(self, x):
        """Returns the normalized tensor.

        Arguments
        ---------
        x : torch.Tensor
            Tensor size [N, C, K, S] or [N, C, L]
        """
        # x: N x C x K x S or N x C x L
        # N x K x S x C
        if x.dim() == 4:
            x = x.permute(0, 2, 3, 1).contiguous()
            # N x K x S x C == only channel norm
            x = super().forward(x)
            # N x C x K x S
            x = x.permute(0, 3, 1, 2).contiguous()
        if x.dim() == 3:
            x = torch.transpose(x, 1, 2)
            # N x L x C == only channel norm
            x = super().forward(x)
            # N x C x L
            x = torch.transpose(x, 1, 2)
        return x


def select_norm(norm, dim, shape):
    """Just a wrapper to select the normalization type.
    """

    if norm == "gln":
        return GlobalLayerNorm(dim, shape, elementwise_affine=True)
    if norm == "cln":
        return CumulativeLayerNorm(dim, elementwise_affine=True)
    if norm == "ln":
        return nn.GroupNorm(1, dim, eps=1e-8)
    else:
        return nn.BatchNorm1d(dim)


class Encoder(nn.Module):
    """Convolutional Encoder Layer.

    Arguments
    ---------
    kernel_size : int
        Length of filters.
    in_channels : int
        Number of  input channels.
    out_channels : int
        Number of output channels.

    Example
    -------
    >>> x = torch.randn(2, 1000)
    >>> encoder = Encoder(kernel_size=4, out_channels=64)
    >>> h = encoder(x)
    >>> h.shape
    torch.Size([2, 64, 499])
    """

    def __init__(self, kernel_size=2, out_channels=64, in_channels=1):
        super(Encoder, self).__init__()
        self.conv1d = nn.Conv1d(
            in_channels=in_channels,
            out_channels=out_channels,
            kernel_size=kernel_size,
            stride=kernel_size // 2,
            groups=1,
            bias=False,
        )
        self.in_channels = in_channels

    def forward(self, x):
        """Return the encoded output.

        Arguments
        ---------
        x : torch.Tensor
            Input tensor with dimensionality [B, L].
        Return
        ------
        x : torch.Tensor
            Encoded tensor with dimensionality [B, N, T_out].

        where B = Batchsize
              L = Number of timepoints
              N = Number of filters
              T_out = Number of timepoints at the output of the encoder
        """
        # B x L -> B x 1 x L
        if self.in_channels == 1:
            x = torch.unsqueeze(x, dim=1)
        # B x 1 x L -> B x N x T_out
        x = self.conv1d(x)
        x = F.relu(x)

        return x


class Decoder(nn.ConvTranspose1d):
    """A decoder layer that consists of ConvTranspose1d.

    Arguments
    ---------
    kernel_size : int
        Length of filters.
    in_channels : int
        Number of  input channels.
    out_channels : int
        Number of output channels.


    Example
    ---------
    >>> x = torch.randn(2, 100, 1000)
    >>> decoder = Decoder(kernel_size=4, in_channels=100, out_channels=1)
    >>> h = decoder(x)
    >>> h.shape
    torch.Size([2, 1003])
    """

    def __init__(self, *args, **kwargs):
        super(Decoder, self).__init__(*args, **kwargs)

    def forward(self, x):
        """Return the decoded output.

        Arguments
        ---------
        x : torch.Tensor
            Input tensor with dimensionality [B, N, L].
                where, B = Batchsize,
                       N = number of filters
                       L = time points
        """

        if x.dim() not in [2, 3]:
            raise RuntimeError(
                "{} accept 3/4D tensor as input".format(self.__name__)
            )
        x = super().forward(x if x.dim() == 3 else torch.unsqueeze(x, 1))

        if torch.squeeze(x).dim() == 1:
            x = torch.squeeze(x, dim=1)
        else:
            x = torch.squeeze(x)
        return x


class IdentityBlock:
    """This block is used when we want to have identity transformation within the Dual_path block.

    Example
    -------
    >>> x = torch.randn(10, 100)
    >>> IB = IdentityBlock()
    >>> xhat = IB(x)
    """

    def _init__(self, **kwargs):
        pass

    def __call__(self, x):
        return x


class MossFormerM(nn.Module):
    """This class implements the MossFormer2 block.

    Arguments
    ---------
    num_blocks : int
        Number of mossformer blocks to include.
    d_model : int
        The dimension of the input embedding.
    attn_dropout : float
        Dropout for the self-attention (Optional).
    group_size: int
        the chunk size
    query_key_dim: int
        the attention vector dimension
    expansion_factor: int
        the expansion factor for the linear projection in conv module
    causal: bool
        true for causal / false for non causal

    Example
    -------
    >>> import torch
    >>> x = torch.rand((8, 60, 512))
    >>> net = MossFormerM(num_blocks=8, d_model=512)
    >>> output, _ = net(x)
    >>> output.shape
    torch.Size([8, 60, 512])
    """
    def __init__(
        self,
        num_blocks,
        d_model=None,
        causal=False,
        group_size = 256,
        query_key_dim = 128,
        expansion_factor = 4.,
        attn_dropout = 0.1
    ):
        super().__init__()

        self.mossformerM = MossformerBlock_GFSMN(
                           dim=d_model,
                           depth=num_blocks,
                           group_size=group_size,
                           query_key_dim=query_key_dim,
                           expansion_factor=expansion_factor,
                           causal=causal,
                           attn_dropout=attn_dropout
                              )
        self.norm = nn.LayerNorm(d_model, eps=1e-6)
    def forward(
        self,
        src,
    ):
        """
        Arguments
        ----------
        src : torch.Tensor
            Tensor shape [B, L, N],
            where, B = Batchsize,
                   L = time points
                   N = number of filters
            The sequence to the encoder layer (required).
        src_mask : tensor
            The mask for the src sequence (optional).
        src_key_padding_mask : tensor
            The mask for the src keys per batch (optional).
        """
        output = self.mossformerM(src)
        output = self.norm(output)

        return output

class MossFormerM2(nn.Module):
    """This class implements the MossFormer block.

    Arguments
    ---------
    num_blocks : int
        Number of mossformer blocks to include.
    d_model : int
        The dimension of the input embedding.
    attn_dropout : float
        Dropout for the self-attention (Optional).
    group_size: int
        the chunk size
    query_key_dim: int
        the attention vector dimension
    expansion_factor: int
        the expansion factor for the linear projection in conv module
    causal: bool
        true for causal / false for non causal

    Example
    -------
    >>> import torch
    >>> x = torch.rand((8, 60, 512))
    >>> net = MossFormerM2(num_blocks=8, d_model=512)
    >>> output, _ = net(x)
    >>> output.shape
    torch.Size([8, 60, 512])
    """
    def __init__(
        self,
        num_blocks,
        d_model=None,
        causal=False,
        group_size = 256,
        query_key_dim = 128,
        expansion_factor = 4.,
        attn_dropout = 0.1
    ):
        super().__init__()

        self.mossformerM = MossformerBlock(
                           dim=d_model,
                           depth=num_blocks,
                           group_size=group_size,
                           query_key_dim=query_key_dim,
                           expansion_factor=expansion_factor,
                           causal=causal,
                           attn_dropout=attn_dropout
                              )
        self.norm = nn.LayerNorm(d_model, eps=1e-6)

    def forward(
        self,
        src,
    ):
        """
        Arguments
        ----------
        src : torch.Tensor
            Tensor shape [B, L, N],
            where, B = Batchsize,
                   L = time points
                   N = number of filters
            The sequence to the encoder layer (required).
        src_mask : tensor
            The mask for the src sequence (optional).
        src_key_padding_mask : tensor
            The mask for the src keys per batch (optional).
        """
        output = self.mossformerM(src)
        output = self.norm(output)

        return output

class Computation_Block(nn.Module):
    """Computation block for dual-path processing.

    Arguments
    ---------
    intra_mdl : torch.nn.module
        Model to process within the chunks.
     inter_mdl : torch.nn.module
        Model to process across the chunks.
     out_channels : int
        Dimensionality of inter/intra model.
     norm : str
        Normalization type.
     skip_around_intra : bool
        Skip connection around the intra layer.
     linear_layer_after_inter_intra : bool
        Linear layer or not after inter or intra.

    Example
    ---------
        >>> comp_block = Computation_Block(64)
        >>> x = torch.randn(10, 64, 100)
        >>> x = comp_block(x)
        >>> x.shape
        torch.Size([10, 64, 100])
    """

    def __init__(
        self,
        num_blocks,
        out_channels,
        norm="ln",
        skip_around_intra=True,
    ):
        super(Computation_Block, self).__init__()

        ##MossFormer+: MossFormer with recurrence
        self.intra_mdl = MossFormerM(num_blocks=num_blocks, d_model=out_channels)
        ##MossFormerM2: the orignal MossFormer
        #self.intra_mdl = MossFormerM2(num_blocks=num_blocks, d_model=out_channels)
        self.skip_around_intra = skip_around_intra

        # Norm
        self.norm = norm
        if norm is not None:
            self.intra_norm = select_norm(norm, out_channels, 3)

    def forward(self, x):
        """Returns the output tensor.

        Arguments
        ---------
        x : torch.Tensor
            Input tensor of dimension [B, N, S].


        Return
        ---------
        out: torch.Tensor
            Output tensor of dimension [B, N, S].
            where, B = Batchsize,
               N = number of filters
               S = sequence time index 
        """
        B, N, S = x.shape
        # [B, S, N]
        intra = x.permute(0, 2, 1).contiguous() #.view(B, S, N)

        intra = self.intra_mdl(intra)

        # [B, N, S]
        intra = intra.permute(0, 2, 1).contiguous()
        if self.norm is not None:
            intra = self.intra_norm(intra)

        # [B, N, S]
        if self.skip_around_intra:
            intra = intra + x

        out = intra
        return out


class MossFormer_MaskNet(nn.Module):
    """The MossFormer MaskNet for predicting mask for encoder output features.
       The MossFormer2 model uses an upgraded MaskNet structure

    Arguments
    ---------
    in_channels : int
        Number of channels at the output of the encoder.
    out_channels : int
        Number of channels that would be inputted to the intra and inter blocks.
    intra_model : torch.nn.module
        Model to process within the chunks.
    num_layers : int
        Number of layers of Dual Computation Block.
    norm : str
        Normalization type.
    num_spks : int
        Number of sources (speakers).
    skip_around_intra : bool
        Skip connection around intra.
    use_global_pos_enc : bool
        Global positional encodings.
    max_length : int
        Maximum sequence length.

    Example
    ---------
    >>> mossformer_masknet = MossFormer_MaskNet(64, 64, num_spks=2)
    >>> x = torch.randn(10, 64, 2000)
    >>> x = mossformer_masknet(x)
    >>> x.shape
    torch.Size([2, 10, 64, 2000])
    """

    def __init__(
        self,
        in_channels,
        out_channels,
        num_blocks=24,
        norm="ln",
        num_spks=2,
        skip_around_intra=True,
        use_global_pos_enc=True,
        max_length=20000,
    ):
        super(MossFormer_MaskNet, self).__init__()
        self.num_spks = num_spks
        self.num_blocks = num_blocks
        self.norm = select_norm(norm, in_channels, 3)
        self.conv1d_encoder = nn.Conv1d(in_channels, out_channels, 1, bias=False)
        self.use_global_pos_enc = use_global_pos_enc

        if self.use_global_pos_enc:
            self.pos_enc = ScaledSinuEmbedding(out_channels)

        self.mdl = Computation_Block(
                    num_blocks,
                    out_channels,
                    norm,
                    skip_around_intra=skip_around_intra,
                )

        self.conv1d_out = nn.Conv1d(
            out_channels, out_channels * num_spks, kernel_size=1
        )
        self.conv1_decoder = nn.Conv1d(out_channels, in_channels, 1, bias=False)
        self.prelu = nn.PReLU()
        self.activation = nn.ReLU()
        # gated output layer
        self.output = nn.Sequential(
            nn.Conv1d(out_channels, out_channels, 1), nn.Tanh()
        )
        self.output_gate = nn.Sequential(
            nn.Conv1d(out_channels, out_channels, 1), nn.Sigmoid()
        )

    def forward(self, x):
        """Returns the output tensor.

        Arguments
        ---------
        x : torch.Tensor
            Input tensor of dimension [B, N, S].

        Returns
        -------
        out : torch.Tensor
            Output tensor of dimension [spks, B, N, S]
            where, spks = Number of speakers
               B = Batchsize,
               N = number of filters
               S = the number of time frames
        """

        # before each line we indicate the shape after executing the line

        # [B, N, L]
        x = self.norm(x)

        # [B, N, L]
        x = self.conv1d_encoder(x)
        if self.use_global_pos_enc:
            base = x
            x = x.transpose(1, -1)
            emb = self.pos_enc(x)
            emb = emb.transpose(0, -1) 
            x = base + emb
            

        # [B, N, S]
        x = self.mdl(x)
        x = self.prelu(x)

        # [B, N*spks, S]
        x = self.conv1d_out(x)
        B, _, S = x.shape

        # [B*spks, N, S]
        x = x.view(B * self.num_spks, -1, S)

        # [B*spks, N, S]
        x = self.output(x) * self.output_gate(x)

        # [B*spks, N, S]
        x = self.conv1_decoder(x)

        # [B, spks, N, S]
        _, N, L = x.shape
        x = x.view(B, self.num_spks, N, L)
        x = self.activation(x)

        # [spks, B, N, S]
        x = x.transpose(0, 1)

        return x

class MossFormer(nn.Module):
    """ The E2E Encoder-MaskNet-Decoder MossFormer model for speech separation
        The MossFormer2 model uses an upgraded MaskNet
    ---------
    Arguments
    ---------
    in_channels : int
        Number of channels at the output of the encoder.
    out_channels : int
        Number of channels that would be inputted to the MossFormer2 blocks.
    num_layers : int
        Number of layers of Dual Computation Block.
    norm : str
        Normalization type.
    num_spks : int
        Number of sources (speakers).
    skip_around_intra : bool
        Skip connection around intra.
    use_global_pos_enc : bool
        Global positional encodings.
    max_length : int
        Maximum sequence length.

    Example
    ---------
    >>> mossformer = MossFormer(num_spks=2)
    >>> x = torch.randn(1, 10000)
    >>> x = mossformer(x)
    >>> x
    x[0]: torch.Size([1, 10000])
    x[1]: torch.Size([1, 10000])
    """
    def __init__(
        self,
        in_channels=512,
        out_channels=512,
        num_blocks=24,
        kernel_size=16,
        norm="ln",
        num_spks=2,
        skip_around_intra=True,
        use_global_pos_enc=True,
        max_length=20000,
    ):
        super(MossFormer, self).__init__()
        self.num_spks = num_spks
        self.enc = Encoder(kernel_size=kernel_size, out_channels=in_channels, in_channels=1)
        self.mask_net = MossFormer_MaskNet(
            in_channels=in_channels,
            out_channels=out_channels,
            num_blocks=num_blocks,
            norm=norm,
            num_spks=num_spks,
            skip_around_intra=skip_around_intra,
            use_global_pos_enc=use_global_pos_enc,
            max_length=max_length,
        )
        self.dec = Decoder(
           in_channels=out_channels,
           out_channels=1,
           kernel_size=kernel_size,
           stride = kernel_size//2,
           bias=False
        )
    def forward(self, input):
        x = self.enc(input)
        mask = self.mask_net(x)
        x = torch.stack([x] * self.num_spks)
        sep_x = x * mask

        # Decoding
        est_source = torch.cat(
            [
                self.dec(sep_x[i]).unsqueeze(-1)
                for i in range(self.num_spks)
            ],
            dim=-1,
        )
        T_origin = input.size(1)
        T_est = est_source.size(1)
        if T_origin > T_est:
            est_source = F.pad(est_source, (0, 0, 0, T_origin - T_est))
        else:
            est_source = est_source[:, :T_origin, :]

        out = []
        for spk in range(self.num_spks):
            out.append(est_source[:,:,spk])
        return out


class MossFormer2_SS_16K(nn.Module):
    """MossFormer2 model wrapper for outside calling"""

    def __init__(self, args):
        super(MossFormer2_SS_16K, self).__init__()
        self.model = MossFormer(
            in_channels=args.encoder_embedding_dim,
            out_channels=args.mossformer_sequence_dim,
            num_blocks=args.num_mossformer_layer,
            kernel_size=args.encoder_kernel_size,
            norm="ln",
            num_spks=args.num_spks,
            skip_around_intra=True,
            use_global_pos_enc=True,
            max_length=20000)

    def forward(self, x):
        outputs = self.model(x)
        return outputs