model.py

import torch.nn as nn

class CRNN(nn.Module):

    def __init__(self, num_classes):
        super().__init__()
        self.cnn = nn.Sequential(nn.Conv2d(1, 64, 3, padding=1), nn.BatchNorm2d(64), nn.ReLU(inplace=True), nn.MaxPool2d((2, 2)), nn.Conv2d(64, 128, 3, padding=1), nn.BatchNorm2d(128), nn.ReLU(inplace=True), nn.MaxPool2d((2, 2)), nn.Conv2d(128, 256, 3, padding=1), nn.BatchNorm2d(256), nn.ReLU(inplace=True), nn.MaxPool2d((2, 1)), nn.Conv2d(256, 256, 3, padding=1), nn.BatchNorm2d(256), nn.ReLU(inplace=True), nn.MaxPool2d((2, 1)), nn.Conv2d(256, 384, 3, padding=1), nn.BatchNorm2d(384), nn.ReLU(inplace=True), nn.MaxPool2d((2, 1)), nn.Conv2d(384, 384, 3, padding=1), nn.BatchNorm2d(384), nn.ReLU(inplace=True), nn.AdaptiveAvgPool2d((1, None)))
        self.rnn = nn.LSTM(input_size=384, hidden_size=256, num_layers=2, bidirectional=True, batch_first=True, dropout=0.2)
        self.classifier = nn.Linear(512, num_classes)

    def forward(self, x):
        x = self.cnn(x)
        x = x.squeeze(2)
        x = x.permute(0, 2, 1)
        x, _ = self.rnn(x)
        return self.classifier(x)