stable_audio_tools/models/blocks.py

from functools import reduce
import math
import numpy as np
import torch
from torch import nn
from torch.nn import functional as F

from torch.backends.cuda import sdp_kernel
from packaging import version

from dac.nn.layers import Snake1d

class ResidualBlock(nn.Module):
    def __init__(self, main, skip=None):
        super().__init__()
        self.main = nn.Sequential(*main)
        self.skip = skip if skip else nn.Identity()

    def forward(self, input):
        return self.main(input) + self.skip(input)

class ResConvBlock(ResidualBlock):
    def __init__(self, c_in, c_mid, c_out, is_last=False, kernel_size=5, conv_bias=True, use_snake=False):
        skip = None if c_in == c_out else nn.Conv1d(c_in, c_out, 1, bias=False)
        super().__init__([
            nn.Conv1d(c_in, c_mid, kernel_size, padding=kernel_size//2, bias=conv_bias),
            nn.GroupNorm(1, c_mid),
            Snake1d(c_mid) if use_snake else nn.GELU(),
            nn.Conv1d(c_mid, c_out, kernel_size, padding=kernel_size//2, bias=conv_bias),
            nn.GroupNorm(1, c_out) if not is_last else nn.Identity(),
            (Snake1d(c_out) if use_snake else nn.GELU()) if not is_last else nn.Identity(),
        ], skip)

class SelfAttention1d(nn.Module):
    def __init__(self, c_in, n_head=1, dropout_rate=0.):
        super().__init__()
        assert c_in % n_head == 0
        self.norm = nn.GroupNorm(1, c_in)
        self.n_head = n_head
        self.qkv_proj = nn.Conv1d(c_in, c_in * 3, 1)
        self.out_proj = nn.Conv1d(c_in, c_in, 1)
        self.dropout = nn.Dropout(dropout_rate, inplace=True)

    def forward(self, input):
        n, c, s = input.shape
        qkv = self.qkv_proj(self.norm(input))
        qkv = qkv.view(
            [n, self.n_head * 3, c // self.n_head, s]).transpose(2, 3)
        q, k, v = qkv.chunk(3, dim=1)
        scale = k.shape[3]**-0.25

        att = ((q * scale) @ (k.transpose(2, 3) * scale)).softmax(3)
        y = (att @ v).transpose(2, 3).contiguous().view([n, c, s])

        return input + self.dropout(self.out_proj(y))

class SkipBlock(nn.Module):
    def __init__(self, *main):
        super().__init__()
        self.main = nn.Sequential(*main)

    def forward(self, input):
        return torch.cat([self.main(input), input], dim=1)

class FourierFeatures(nn.Module):
    def __init__(self, in_features, out_features, std=1.):
        super().__init__()
        assert out_features % 2 == 0
        self.weight = nn.Parameter(torch.randn(
            [out_features // 2, in_features]) * std)

    def forward(self, input):
        f = 2 * math.pi * input @ self.weight.T
        return torch.cat([f.cos(), f.sin()], dim=-1)

def expand_to_planes(input, shape):
    return input[..., None].repeat([1, 1, shape[2]])

_kernels = {
    'linear':
        [1 / 8, 3 / 8, 3 / 8, 1 / 8],
    'cubic': 
        [-0.01171875, -0.03515625, 0.11328125, 0.43359375,
        0.43359375, 0.11328125, -0.03515625, -0.01171875],
    'lanczos3': 
        [0.003689131001010537, 0.015056144446134567, -0.03399861603975296,
        -0.066637322306633, 0.13550527393817902, 0.44638532400131226,
        0.44638532400131226, 0.13550527393817902, -0.066637322306633,
        -0.03399861603975296, 0.015056144446134567, 0.003689131001010537]
}

class Downsample1d(nn.Module):
    def __init__(self, kernel='linear', pad_mode='reflect', channels_last=False):
        super().__init__()
        self.pad_mode = pad_mode
        kernel_1d = torch.tensor(_kernels[kernel])
        self.pad = kernel_1d.shape[0] // 2 - 1
        self.register_buffer('kernel', kernel_1d)
        self.channels_last = channels_last
    
    def forward(self, x):
        if self.channels_last:
            x = x.permute(0, 2, 1)
        x = F.pad(x, (self.pad,) * 2, self.pad_mode)
        weight = x.new_zeros([x.shape[1], x.shape[1], self.kernel.shape[0]])
        indices = torch.arange(x.shape[1], device=x.device)
        weight[indices, indices] = self.kernel.to(weight)
        x = F.conv1d(x, weight, stride=2)
        if self.channels_last:
            x = x.permute(0, 2, 1)
        return x


class Upsample1d(nn.Module):
    def __init__(self, kernel='linear', pad_mode='reflect', channels_last=False):
        super().__init__()
        self.pad_mode = pad_mode
        kernel_1d = torch.tensor(_kernels[kernel]) * 2
        self.pad = kernel_1d.shape[0] // 2 - 1
        self.register_buffer('kernel', kernel_1d)
        self.channels_last = channels_last
    
    def forward(self, x):
        if self.channels_last:
            x = x.permute(0, 2, 1)
        x = F.pad(x, ((self.pad + 1) // 2,) * 2, self.pad_mode)
        weight = x.new_zeros([x.shape[1], x.shape[1], self.kernel.shape[0]])
        indices = torch.arange(x.shape[1], device=x.device)
        weight[indices, indices] = self.kernel.to(weight)
        x = F.conv_transpose1d(x, weight, stride=2, padding=self.pad * 2 + 1)
        if self.channels_last:
            x = x.permute(0, 2, 1)
        return x
        
def Downsample1d_2(
    in_channels: int, out_channels: int, factor: int, kernel_multiplier: int = 2
) -> nn.Module:
    assert kernel_multiplier % 2 == 0, "Kernel multiplier must be even"

    return nn.Conv1d(
        in_channels=in_channels,
        out_channels=out_channels,
        kernel_size=factor * kernel_multiplier + 1,
        stride=factor,
        padding=factor * (kernel_multiplier // 2),
    )


def Upsample1d_2(
    in_channels: int, out_channels: int, factor: int, use_nearest: bool = False
) -> nn.Module:

    if factor == 1:
        return nn.Conv1d(
            in_channels=in_channels, out_channels=out_channels, kernel_size=3, padding=1
        )

    if use_nearest:
        return nn.Sequential(
            nn.Upsample(scale_factor=factor, mode="nearest"),
            nn.Conv1d(
                in_channels=in_channels,
                out_channels=out_channels,
                kernel_size=3,
                padding=1,
            ),
        )
    else:
        return nn.ConvTranspose1d(
            in_channels=in_channels,
            out_channels=out_channels,
            kernel_size=factor * 2,
            stride=factor,
            padding=factor // 2 + factor % 2,
            output_padding=factor % 2,
        )

def zero_init(layer):
    nn.init.zeros_(layer.weight)
    if layer.bias is not None:
        nn.init.zeros_(layer.bias)
    return layer

def rms_norm(x, scale, eps):
    dtype = reduce(torch.promote_types, (x.dtype, scale.dtype, torch.float32))
    mean_sq = torch.mean(x.to(dtype)**2, dim=-1, keepdim=True)
    scale = scale.to(dtype) * torch.rsqrt(mean_sq + eps)
    return x * scale.to(x.dtype)

#rms_norm = torch.compile(rms_norm)

class AdaRMSNorm(nn.Module):
    def __init__(self, features, cond_features, eps=1e-6):
        super().__init__()
        self.eps = eps
        self.linear = zero_init(nn.Linear(cond_features, features, bias=False))
  
    def extra_repr(self):
        return f"eps={self.eps},"

    def forward(self, x, cond):
        return rms_norm(x, self.linear(cond)[:, None, :] + 1, self.eps)
    
def normalize(x, eps=1e-4):
    dim = list(range(1, x.ndim))
    n = torch.linalg.vector_norm(x, dim=dim, keepdim=True)
    alpha = np.sqrt(n.numel() / x.numel())
    return x / torch.add(eps, n, alpha=alpha)

class ForcedWNConv1d(nn.Module):
    def __init__(self, in_channels, out_channels, kernel_size=1):
        super().__init__()
        self.weight = nn.Parameter(torch.randn([out_channels, in_channels, kernel_size]))

    def forward(self, x):
        if self.training:
            with torch.no_grad():
                self.weight.copy_(normalize(self.weight))
        
        fan_in = self.weight[0].numel()

        w = normalize(self.weight) / math.sqrt(fan_in)

        return F.conv1d(x, w, padding='same')
        
# Kernels

# use_compile = True
use_compile = False

def compile(function, *args, **kwargs):
    if not use_compile:
        return function
    try:
        return torch.compile(function, *args, **kwargs)
    except RuntimeError:
        return function


@compile
def linear_geglu(x, weight, bias=None):
    x = x @ weight.mT
    if bias is not None:
        x = x + bias
    x, gate = x.chunk(2, dim=-1)
    return x * F.gelu(gate)


@compile
def rms_norm(x, scale, eps):
    dtype = reduce(torch.promote_types, (x.dtype, scale.dtype, torch.float32))
    mean_sq = torch.mean(x.to(dtype)**2, dim=-1, keepdim=True)
    scale = scale.to(dtype) * torch.rsqrt(mean_sq + eps)
    return x * scale.to(x.dtype)

# Layers

class LinearGEGLU(nn.Linear):
    def __init__(self, in_features, out_features, bias=True):
        super().__init__(in_features, out_features * 2, bias=bias)
        self.out_features = out_features

    def forward(self, x):
        return linear_geglu(x, self.weight, self.bias)


class RMSNorm(nn.Module):
    def __init__(self, shape, fix_scale = False, eps=1e-6):
        super().__init__()
        self.eps = eps

        if fix_scale:
            self.register_buffer("scale", torch.ones(shape))
        else:
            self.scale = nn.Parameter(torch.ones(shape))

    def extra_repr(self):
        return f"shape={tuple(self.scale.shape)}, eps={self.eps}"

    def forward(self, x):
        return rms_norm(x, self.scale, self.eps)    

def snake_beta(x, alpha, beta):
    return x + (1.0 / (beta + 0.000000001)) * pow(torch.sin(x * alpha), 2)

# try:
#     snake_beta = torch.compile(snake_beta)
# except RuntimeError:
#     pass

# Adapted from https://github.com/NVIDIA/BigVGAN/blob/main/activations.py under MIT license
# License available in LICENSES/LICENSE_NVIDIA.txt
class SnakeBeta(nn.Module):

    def __init__(self, in_features, alpha=1.0, alpha_trainable=True, alpha_logscale=True):
        super(SnakeBeta, self).__init__()
        self.in_features = in_features

        # initialize alpha
        self.alpha_logscale = alpha_logscale
        if self.alpha_logscale: # log scale alphas initialized to zeros
            self.alpha = nn.Parameter(torch.zeros(in_features) * alpha)
            self.beta = nn.Parameter(torch.zeros(in_features) * alpha)
        else: # linear scale alphas initialized to ones
            self.alpha = nn.Parameter(torch.ones(in_features) * alpha)
            self.beta = nn.Parameter(torch.ones(in_features) * alpha)

        self.alpha.requires_grad = alpha_trainable
        self.beta.requires_grad = alpha_trainable

        self.no_div_by_zero = 0.000000001

    def forward(self, x):
        alpha = self.alpha.unsqueeze(0).unsqueeze(-1) # line up with x to [B, C, T]
        beta = self.beta.unsqueeze(0).unsqueeze(-1)
        if self.alpha_logscale:
            alpha = torch.exp(alpha)
            beta = torch.exp(beta)
        x = snake_beta(x, alpha, beta)

        return x