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encoder.py

@@ -0,0 +1,601 @@
+"""Copied from https://github.com/salute-developers/GigaAM/blob/main/gigaam/encoder.py"""
+import math
+from abc import ABC, abstractmethod
+from typing import List, Optional, Tuple, Union
+
+import torch
+from torch import Tensor, nn
+
+try:
+    from flash_attn import flash_attn_func
+
+    IMPORT_FLASH = True
+except Exception as err:
+    IMPORT_FLASH = False
+    IMPORT_FLASH_ERR = err
+
+# from .utils import apply_masked_flash_attn, apply_rotary_pos_emb
+
+
+def rtt_half(x: Tensor) -> Tensor:
+    x1, x2 = x[..., : x.shape[-1] // 2], x[..., x.shape[-1] // 2 :]
+    return torch.cat([-x2, x1], dim=x1.ndim - 1)
+
+
+def apply_rotary_pos_emb(
+    q: Tensor, k: Tensor, cos: Tensor, sin: Tensor, offset: int = 0
+) -> Tuple[Tensor, Tensor]:
+    """
+    Applies Rotary Position Embeddings to query and key tensors.
+    """
+    cos, sin = (
+        cos[offset : q.shape[0] + offset, ...],
+        sin[offset : q.shape[0] + offset, ...],
+    )
+    return (q * cos) + (rtt_half(q) * sin), (k * cos) + (rtt_half(k) * sin)
+
+
+def apply_masked_flash_attn(
+    q: Tensor,
+    k: Tensor,
+    v: Tensor,
+    mask: Tensor,
+    h: int,
+    d_k: int,
+) -> Tensor:
+    """
+    Applies Flash Attention with padding masks.
+    """
+
+    from einops import rearrange
+    from flash_attn import flash_attn_varlen_func
+    from flash_attn.bert_padding import pad_input, unpad_input
+
+    pad_mask = ~mask[:, 0, :]
+    b, t = pad_mask.shape
+    q = q.view(b, t, h * d_k)
+    k = k.view(b, t, h * d_k)
+    v = v.view(b, t, h * d_k)
+
+    q_unpad, indices_q, _, max_seqlen_q = unpad_input(q, pad_mask)[:4]
+    q_unpad = rearrange(q_unpad, "nnz (h d) -> nnz h d", h=h)
+
+    k_unpad = unpad_input(k, pad_mask)[0]
+    k_unpad = rearrange(k_unpad, "nnz (h d) -> nnz h d", h=h)
+
+    v_unpad = unpad_input(v, pad_mask)[0]
+    v_unpad = rearrange(v_unpad, "nnz (h d) -> nnz h d", h=h)
+
+    lengths_q = pad_mask.sum(1).to(torch.int32).to(q.device)
+    cu_seqlens_q = F.pad(lengths_q.cumsum(0), (1, 0), value=0).to(torch.int32)
+    max_seqlen_q = torch.max(lengths_q)
+
+    output_unpad = flash_attn_varlen_func(
+        q_unpad,
+        k_unpad,
+        v_unpad,
+        cu_seqlens_q,
+        cu_seqlens_q,
+        max_seqlen_q,
+        max_seqlen_q,
+    )
+
+    scores = pad_input(
+        rearrange(output_unpad, "nnz h d -> nnz (h d)"),
+        indices_q,
+        b,
+        t,
+    )
+
+    return scores
+
+
+class StridingSubsampling(nn.Module):
+    """
+    Strided Subsampling layer used to reduce the sequence length.
+    """
+
+    def __init__(
+        self,
+        subsampling_factor: int,
+        feat_in: int,
+        feat_out: int,
+        conv_channels: int,
+    ):
+        super().__init__()
+        self._sampling_num = int(math.log(subsampling_factor, 2))
+        self._stride = 2
+        self._kernel_size = 3
+        self._padding = (self._kernel_size - 1) // 2
+
+        layers: List[nn.Module] = []
+        in_channels = 1
+        for _ in range(self._sampling_num):
+            layers.append(
+                torch.nn.Conv2d(
+                    in_channels=in_channels,
+                    out_channels=conv_channels,
+                    kernel_size=self._kernel_size,
+                    stride=self._stride,
+                    padding=self._padding,
+                )
+            )
+            layers.append(nn.ReLU())
+            in_channels = conv_channels
+
+        out_length = self.calc_output_length(torch.tensor(feat_in))
+        self.out = torch.nn.Linear(conv_channels * int(out_length), feat_out)
+        self.conv = torch.nn.Sequential(*layers)
+
+    def calc_output_length(self, lengths: Tensor) -> Tensor:
+        """
+        Calculates the output length after applying the subsampling.
+        """
+        lengths = lengths.to(torch.float)
+        add_pad = 2 * self._padding - self._kernel_size
+        for _ in range(self._sampling_num):
+            lengths = torch.div(lengths + add_pad, self._stride) + 1.0
+            lengths = torch.floor(lengths)
+        return lengths.to(dtype=torch.int)
+
+    def forward(self, x: Tensor, lengths: Tensor) -> Tuple[Tensor, Tensor]:
+        x = self.conv(x.unsqueeze(1))
+        b, _, t, _ = x.size()
+        x = self.out(x.transpose(1, 2).reshape(b, t, -1))
+        return x, self.calc_output_length(lengths)
+
+
+class MultiHeadAttention(nn.Module, ABC):
+    """
+    Base class of Multi-Head Attention Mechanisms.
+    """
+
+    def __init__(self, n_head: int, n_feat: int, flash_attn=False):
+        super().__init__()
+        assert n_feat % n_head == 0
+        self.d_k = n_feat // n_head
+        self.h = n_head
+        self.linear_q = nn.Linear(n_feat, n_feat)
+        self.linear_k = nn.Linear(n_feat, n_feat)
+        self.linear_v = nn.Linear(n_feat, n_feat)
+        self.linear_out = nn.Linear(n_feat, n_feat)
+        self.flash_attn = flash_attn
+        if self.flash_attn and not IMPORT_FLASH:
+            raise RuntimeError(
+                f"flash_attn_func was imported with err {IMPORT_FLASH_ERR}. "
+                "Please install flash_attn or use --no_flash flag. "
+                "If you have already done this, "
+                "--force-reinstall flag might be useful"
+            )
+
+    def forward_qkv(
+        self, query: Tensor, key: Tensor, value: Tensor
+    ) -> Tuple[Tensor, Tensor, Tensor]:
+        """
+        Projects the inputs into queries, keys, and values for multi-head attention.
+        """
+        b = query.size(0)
+        q = self.linear_q(query).view(b, -1, self.h, self.d_k)
+        k = self.linear_k(key).view(b, -1, self.h, self.d_k)
+        v = self.linear_v(value).view(b, -1, self.h, self.d_k)
+        if self.flash_attn:
+            return q, k, v
+        return q.transpose(1, 2), k.transpose(1, 2), v.transpose(1, 2)
+
+    def forward_attention(
+        self, value: Tensor, scores: Tensor, mask: Optional[Tensor]
+    ) -> Tensor:
+        """
+        Computes the scaled dot-product attention given the projected values and scores.
+        """
+        b = value.size(0)
+        if mask is not None:
+            mask = mask.unsqueeze(1)
+            scores = scores.masked_fill(mask, -10000.0)
+            attn = torch.softmax(scores, dim=-1).masked_fill(mask, 0.0)
+        else:
+            attn = torch.softmax(scores, dim=-1)
+        x = torch.matmul(attn, value)
+        x = x.transpose(1, 2).reshape(b, -1, self.h * self.d_k)
+        return self.linear_out(x)
+
+
+class RelPositionMultiHeadAttention(MultiHeadAttention):
+    """
+    Relative Position Multi-Head Attention module.
+    """
+
+    def __init__(self, n_head: int, n_feat: int):
+        super().__init__(n_head, n_feat)
+        self.linear_pos = nn.Linear(n_feat, n_feat, bias=False)
+        self.pos_bias_u = nn.Parameter(torch.FloatTensor(self.h, self.d_k))
+        self.pos_bias_v = nn.Parameter(torch.FloatTensor(self.h, self.d_k))
+
+    def rel_shift(self, x: Tensor) -> Tensor:
+        b, h, qlen, pos_len = x.size()
+        x = torch.nn.functional.pad(x, pad=(1, 0))
+        x = x.view(b, h, -1, qlen)
+        return x[:, :, 1:].view(b, h, qlen, pos_len)
+
+    def forward(
+        self,
+        query: Tensor,
+        key: Tensor,
+        value: Tensor,
+        pos_emb: Tensor,
+        mask: Optional[Tensor] = None,
+    ) -> Tensor:
+        q, k, v = self.forward_qkv(query, key, value)
+        q = q.transpose(1, 2)
+        p = self.linear_pos(pos_emb)
+        p = p.view(pos_emb.shape[0], -1, self.h, self.d_k).transpose(1, 2)
+        q_with_bias_u = (q + self.pos_bias_u).transpose(1, 2)
+        q_with_bias_v = (q + self.pos_bias_v).transpose(1, 2)
+        matrix_bd = torch.matmul(q_with_bias_v, p.transpose(-2, -1))
+        matrix_bd = self.rel_shift(matrix_bd)
+        matrix_ac = torch.matmul(q_with_bias_u, k.transpose(-2, -1))
+        matrix_bd = matrix_bd[:, :, :, : matrix_ac.size(-1)]
+        scores = (matrix_ac + matrix_bd) / math.sqrt(self.d_k)
+        return self.forward_attention(v, scores, mask)
+
+
+class RotaryPositionMultiHeadAttention(MultiHeadAttention):
+    """
+    Rotary Position Multi-Head Attention module.
+    """
+
+    def forward(
+        self,
+        query: Tensor,
+        key: Tensor,
+        value: Tensor,
+        pos_emb: List[Tensor],
+        mask: Optional[Tensor] = None,
+    ) -> Tensor:
+        b, t, _ = value.size()
+        query = query.transpose(0, 1).view(t, b, self.h, self.d_k)
+        key = key.transpose(0, 1).view(t, b, self.h, self.d_k)
+        value = value.transpose(0, 1).view(t, b, self.h, self.d_k)
+
+        cos, sin = pos_emb
+        query, key = apply_rotary_pos_emb(query, key, cos, sin, offset=0)
+
+        q, k, v = self.forward_qkv(
+            query.view(t, b, self.h * self.d_k).transpose(0, 1),
+            key.view(t, b, self.h * self.d_k).transpose(0, 1),
+            value.view(t, b, self.h * self.d_k).transpose(0, 1),
+        )
+
+        if not self.flash_attn:
+            scores = torch.matmul(q, k.transpose(-2, -1) / math.sqrt(self.d_k))
+            out = self.forward_attention(v, scores, mask)
+        else:
+            if mask is None:
+                scores = flash_attn_func(q, k, v)
+            else:
+                scores = apply_masked_flash_attn(q, k, v, mask, self.h, self.d_k)
+
+            scores = scores.view(b, -1, self.h * self.d_k)
+            out = self.linear_out(scores)
+
+        return out
+
+
+class PositionalEncoding(nn.Module, ABC):
+    """
+    Base class of Positional Encodings.
+    """
+
+    def __init__(self, dim: int, base: int):
+        super().__init__()
+        self.dim = dim
+        self.base = base
+
+    @abstractmethod
+    def create_pe(self, length: int, device: torch.device) -> Optional[Tensor]:
+        pass
+
+    def extend_pe(self, length: int, device: torch.device):
+        """
+        Extends the positional encoding buffer to process longer sequences.
+        """
+        pe = self.create_pe(length, device)
+        if pe is None:
+            return
+        if hasattr(self, "pe"):
+            self.pe = pe
+        else:
+            self.register_buffer("pe", pe, persistent=False)
+
+
+class RelPositionalEmbedding(PositionalEncoding):
+    """
+    Relative Positional Embedding module.
+    """
+
+    def create_pe(self, length: int, device: torch.device) -> Optional[Tensor]:
+        """
+        Creates the relative positional encoding matrix.
+        """
+        if hasattr(self, "pe") and self.pe.shape[1] >= 2 * length - 1:
+            return None
+        positions = torch.arange(length - 1, -length, -1, device=device).unsqueeze(1)
+        pos_length = positions.size(0)
+        pe = torch.zeros(pos_length, self.dim, device=positions.device)
+        div_term = torch.exp(
+            torch.arange(0, self.dim, 2, device=pe.device)
+            * -(math.log(10000.0) / self.dim)
+        )
+        pe[:, 0::2] = torch.sin(positions * div_term)
+        pe[:, 1::2] = torch.cos(positions * div_term)
+        return pe.unsqueeze(0)
+
+    def forward(self, x: torch.Tensor) -> Tuple[Tensor, Tensor]:
+        input_len = x.size(1)
+        center_pos = self.pe.size(1) // 2 + 1
+        start_pos = center_pos - input_len
+        end_pos = center_pos + input_len - 1
+        return x, self.pe[:, start_pos:end_pos]
+
+
+class RotaryPositionalEmbedding(PositionalEncoding):
+    """
+    Rotary Positional Embedding module.
+    """
+
+    def create_pe(self, length: int, device: torch.device) -> Optional[Tensor]:
+        """
+        Creates or extends the rotary positional encoding matrix.
+        """
+        if hasattr(self, "pe") and self.pe.size(0) >= 2 * length:
+            return None
+        positions = torch.arange(0, length, dtype=torch.float32, device=device)
+        inv_freq = 1.0 / (
+            self.base ** (torch.arange(0, self.dim, 2).float() / self.dim)
+        )
+        t = torch.arange(length, device=positions.device).type_as(inv_freq)
+        freqs = torch.einsum("i,j->ij", t, inv_freq)
+        emb = torch.cat((freqs, freqs), dim=-1).to(positions.device)
+        return torch.cat([emb.cos()[:, None, None, :], emb.sin()[:, None, None, :]])
+
+    def forward(self, x: torch.Tensor) -> Tuple[Tensor, List[Tensor]]:
+        cos_emb = self.pe[0 : x.shape[1]]
+        half_pe = self.pe.shape[0] // 2
+        sin_emb = self.pe[half_pe : half_pe + x.shape[1]]
+        return x, [cos_emb, sin_emb]
+
+
+class ConformerConvolution(nn.Module):
+    """
+    Conformer Convolution module.
+    """
+
+    def __init__(
+        self,
+        d_model: int,
+        kernel_size: int,
+    ):
+        super().__init__()
+        assert (kernel_size - 1) % 2 == 0
+        self.pointwise_conv1 = nn.Conv1d(d_model, d_model * 2, kernel_size=1)
+        self.depthwise_conv = nn.Conv1d(
+            in_channels=d_model,
+            out_channels=d_model,
+            kernel_size=kernel_size,
+            padding=(kernel_size - 1) // 2,
+            groups=d_model,
+            bias=True,
+        )
+        self.batch_norm = nn.BatchNorm1d(d_model)
+        self.activation = nn.SiLU()
+        self.pointwise_conv2 = nn.Conv1d(d_model, d_model, kernel_size=1)
+
+    def forward(self, x: Tensor, pad_mask: Optional[Tensor] = None) -> Tensor:
+        x = x.transpose(1, 2)
+        x = self.pointwise_conv1(x)
+        x = nn.functional.glu(x, dim=1)
+        if pad_mask is not None:
+            x = x.masked_fill(pad_mask.unsqueeze(1), 0.0)
+        x = self.depthwise_conv(x)
+        x = self.batch_norm(x)
+        x = self.activation(x)
+        x = self.pointwise_conv2(x)
+        return x.transpose(1, 2)
+
+
+class ConformerFeedForward(nn.Module):
+    """
+    Conformer Feed Forward module.
+    """
+
+    def __init__(self, d_model: int, d_ff: int, use_bias=True):
+        super().__init__()
+        self.linear1 = nn.Linear(d_model, d_ff, bias=use_bias)
+        self.activation = nn.SiLU()
+        self.linear2 = nn.Linear(d_ff, d_model, bias=use_bias)
+
+    def forward(self, x: Tensor) -> Tensor:
+        return self.linear2(self.activation(self.linear1(x)))
+
+
+class ConformerLayer(nn.Module):
+    """
+    Conformer Layer module.
+    This module combines several submodules including feed forward networks,
+    depthwise separable convolution, and multi-head self-attention
+    to form a single Conformer block.
+    """
+
+    def __init__(
+        self,
+        d_model: int,
+        d_ff: int,
+        self_attention_model: str,
+        n_heads: int = 16,
+        conv_kernel_size: int = 31,
+        flash_attn: bool = False,
+    ):
+        super().__init__()
+        self.fc_factor = 0.5
+        self.norm_feed_forward1 = nn.LayerNorm(d_model)
+        self.feed_forward1 = ConformerFeedForward(d_model=d_model, d_ff=d_ff)
+        self.norm_conv = nn.LayerNorm(d_model)
+        self.conv = ConformerConvolution(
+            d_model=d_model,
+            kernel_size=conv_kernel_size,
+        )
+        self.norm_self_att = nn.LayerNorm(d_model)
+        if self_attention_model == "rotary":
+            self.self_attn: nn.Module = RotaryPositionMultiHeadAttention(
+                n_head=n_heads,
+                n_feat=d_model,
+                flash_attn=flash_attn,
+            )
+        else:
+            assert not flash_attn, "Not supported flash_attn for rel_pos"
+            self.self_attn = RelPositionMultiHeadAttention(
+                n_head=n_heads,
+                n_feat=d_model,
+            )
+        self.norm_feed_forward2 = nn.LayerNorm(d_model)
+        self.feed_forward2 = ConformerFeedForward(d_model=d_model, d_ff=d_ff)
+        self.norm_out = nn.LayerNorm(d_model)
+
+    def forward(
+        self,
+        x: Tensor,
+        pos_emb: Union[Tensor, List[Tensor]],
+        att_mask: Optional[Tensor] = None,
+        pad_mask: Optional[Tensor] = None,
+    ) -> Tensor:
+        residual = x
+        x = self.norm_feed_forward1(x)
+        x = self.feed_forward1(x)
+        residual = residual + x * self.fc_factor
+
+        x = self.norm_self_att(residual)
+        x = self.self_attn(x, x, x, pos_emb, mask=att_mask)
+        residual = residual + x
+
+        x = self.norm_conv(residual)
+        x = self.conv(x, pad_mask=pad_mask)
+        residual = residual + x
+
+        x = self.norm_feed_forward2(residual)
+        x = self.feed_forward2(x)
+        residual = residual + x * self.fc_factor
+
+        x = self.norm_out(residual)
+        return x
+
+
+class ConformerEncoder(nn.Module):
+    """
+    Conformer Encoder module.
+    This module encapsulates the entire Conformer encoder architecture,
+    consisting of a StridingSubsampling layer, positional embeddings, and
+    a stack of Conformer Layers.
+    It serves as the main component responsible for processing speech features.
+    """
+
+    def __init__(
+        self,
+        feat_in: int = 64,
+        n_layers: int = 16,
+        d_model: int = 768,
+        subsampling_factor: int = 4,
+        ff_expansion_factor: int = 4,
+        self_attention_model: str = "rotary",
+        n_heads: int = 16,
+        pos_emb_max_len: int = 5000,
+        conv_kernel_size: int = 31,
+        flash_attn: bool = False,
+    ):
+        super().__init__()
+        self.feat_in = feat_in
+        assert self_attention_model in [
+            "rotary",
+            "rel_pos",
+        ], f"Not supported attn = {self_attention_model}"
+
+        self.pre_encode = StridingSubsampling(
+            subsampling_factor=subsampling_factor,
+            feat_in=feat_in,
+            feat_out=d_model,
+            conv_channels=d_model,
+        )
+
+        if self_attention_model == "rotary":
+            self.pos_enc: nn.Module = RotaryPositionalEmbedding(
+                d_model // n_heads, pos_emb_max_len
+            )
+        else:
+            self.pos_enc = RelPositionalEmbedding(d_model, pos_emb_max_len)
+
+        self.layers = nn.ModuleList()
+        for _ in range(n_layers):
+            layer = ConformerLayer(
+                d_model=d_model,
+                d_ff=d_model * ff_expansion_factor,
+                self_attention_model=self_attention_model,
+                n_heads=n_heads,
+                conv_kernel_size=conv_kernel_size,
+                flash_attn=flash_attn,
+            )
+            self.layers.append(layer)
+
+        self.pos_enc.extend_pe(pos_emb_max_len, next(self.parameters()).device)
+
+    def input_example(
+        self,
+        batch_size: int = 1,
+        seqlen: int = 200,
+    ):
+        device = next(self.parameters()).device
+        features = torch.zeros(batch_size, self.feat_in, seqlen)
+        feature_lengths = torch.full([batch_size], features.shape[-1])
+        return features.float().to(device), feature_lengths.to(device)
+
+    def input_names(self):
+        return ["audio_signal", "length"]
+
+    def output_names(self):
+        return ["encoded", "encoded_len"]
+
+    def dynamic_axes(self):
+        return {
+            "audio_signal": {0: "batch_size", 2: "seq_len"},
+            "length": {0: "batch_size"},
+            "encoded": {0: "batch_size", 1: "seq_len"},
+            "encoded_len": {0: "batch_size"},
+        }
+
+    def forward(self, audio_signal: Tensor, length: Tensor) -> Tuple[Tensor, Tensor]:
+        audio_signal, length = self.pre_encode(
+            x=audio_signal.transpose(1, 2), lengths=length
+        )
+
+        max_len = audio_signal.size(1)
+        audio_signal, pos_emb = self.pos_enc(x=audio_signal)
+
+        pad_mask = torch.arange(0, max_len, device=audio_signal.device).expand(
+            length.size(0), -1
+        ) < length.unsqueeze(-1)
+
+        att_mask = None
+        if audio_signal.shape[0] > 1:
+            att_mask = pad_mask.unsqueeze(1).repeat([1, max_len, 1])
+            att_mask = torch.logical_and(att_mask, att_mask.transpose(1, 2))
+            att_mask = ~att_mask
+
+        pad_mask = ~pad_mask
+
+        for layer in self.layers:
+            audio_signal = layer(
+                x=audio_signal,
+                pos_emb=pos_emb,
+                att_mask=att_mask,
+                pad_mask=pad_mask,
+            )
+
+        return audio_signal.transpose(1, 2), length

gigaam_transformers.py

@@ -4,7 +4,7 @@ import numpy as np
 import torch
 import torch.nn as nn
 import torchaudio
-from gigaam.encoder import ConformerEncoder
+from .encoder import ConformerEncoder
 from torch import Tensor
 from transformers import Wav2Vec2CTCTokenizer, Wav2Vec2Processor
 from transformers.configuration_utils import PretrainedConfig