File size: 4,208 Bytes
4dab15f
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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
"""
ein notation:
b - batch
n - sequence
nt - text sequence
nw - raw wave length
d - dimension
"""

from __future__ import annotations

import torch
from torch import nn

from x_transformers.x_transformers import RotaryEmbedding

from f5_tts.model.modules import (
    TimestepEmbedding,
    ConvPositionEmbedding,
    MMDiTBlock,
    AdaLayerNormZero_Final,
    precompute_freqs_cis,
    get_pos_embed_indices,
)


# text embedding


class TextEmbedding(nn.Module):
    def __init__(self, out_dim, text_num_embeds):
        super().__init__()
        self.text_embed = nn.Embedding(text_num_embeds + 1, out_dim)  # will use 0 as filler token

        self.precompute_max_pos = 1024
        self.register_buffer("freqs_cis", precompute_freqs_cis(out_dim, self.precompute_max_pos), persistent=False)

    def forward(self, text: int["b nt"], drop_text=False) -> int["b nt d"]:  # noqa: F722
        text = text + 1
        if drop_text:
            text = torch.zeros_like(text)
        text = self.text_embed(text)

        # sinus pos emb
        batch_start = torch.zeros((text.shape[0],), dtype=torch.long)
        batch_text_len = text.shape[1]
        pos_idx = get_pos_embed_indices(batch_start, batch_text_len, max_pos=self.precompute_max_pos)
        text_pos_embed = self.freqs_cis[pos_idx]

        text = text + text_pos_embed

        return text


# noised input & masked cond audio embedding


class AudioEmbedding(nn.Module):
    def __init__(self, in_dim, out_dim):
        super().__init__()
        self.linear = nn.Linear(2 * in_dim, out_dim)
        self.conv_pos_embed = ConvPositionEmbedding(out_dim)

    def forward(self, x: float["b n d"], cond: float["b n d"], drop_audio_cond=False):  # noqa: F722
        if drop_audio_cond:
            cond = torch.zeros_like(cond)
        x = torch.cat((x, cond), dim=-1)
        x = self.linear(x)
        x = self.conv_pos_embed(x) + x
        return x


# Transformer backbone using MM-DiT blocks


class MMDiT(nn.Module):
    def __init__(
        self,
        *,
        dim,
        depth=8,
        heads=8,
        dim_head=64,
        dropout=0.1,
        ff_mult=4,
        text_num_embeds=256,
        mel_dim=100,
    ):
        super().__init__()

        self.time_embed = TimestepEmbedding(dim)
        self.text_embed = TextEmbedding(dim, text_num_embeds)
        self.audio_embed = AudioEmbedding(mel_dim, dim)

        self.rotary_embed = RotaryEmbedding(dim_head)

        self.dim = dim
        self.depth = depth

        self.transformer_blocks = nn.ModuleList(
            [
                MMDiTBlock(
                    dim=dim,
                    heads=heads,
                    dim_head=dim_head,
                    dropout=dropout,
                    ff_mult=ff_mult,
                    context_pre_only=i == depth - 1,
                )
                for i in range(depth)
            ]
        )
        self.norm_out = AdaLayerNormZero_Final(dim)  # final modulation
        self.proj_out = nn.Linear(dim, mel_dim)

    def forward(
        self,
        x: float["b n d"],  # nosied input audio  # noqa: F722
        cond: float["b n d"],  # masked cond audio  # noqa: F722
        text: int["b nt"],  # text  # noqa: F722
        time: float["b"] | float[""],  # time step  # noqa: F821 F722
        drop_audio_cond,  # cfg for cond audio
        drop_text,  # cfg for text
        mask: bool["b n"] | None = None,  # noqa: F722
    ):
        batch = x.shape[0]
        if time.ndim == 0:
            time = time.repeat(batch)

        # t: conditioning (time), c: context (text + masked cond audio), x: noised input audio
        t = self.time_embed(time)
        c = self.text_embed(text, drop_text=drop_text)
        x = self.audio_embed(x, cond, drop_audio_cond=drop_audio_cond)

        seq_len = x.shape[1]
        text_len = text.shape[1]
        rope_audio = self.rotary_embed.forward_from_seq_len(seq_len)
        rope_text = self.rotary_embed.forward_from_seq_len(text_len)

        for block in self.transformer_blocks:
            c, x = block(x, c, t, mask=mask, rope=rope_audio, c_rope=rope_text)

        x = self.norm_out(x, t)
        output = self.proj_out(x)

        return output