I. Introduction

YOLOv4 have been released on 23 Apr 2020. The new updated version of the popular YOLO object detection neural network which achieves state-of-the-art results on the MS-COCO dataset, running at real-time speed of more than 65 FPS.
Darknet is a framework to train neural networks, it is open source and written in C/CUDA and serves as the basis for YOLO. The original repository, by J Redmon (also first author of the YOLO paper), can be found here. Darknet is used as the framework for training YOLO, meaning it sets the architecture of the network.
Open Images Dataset v4,provided by Google, is the largest existing dataset with object location annotations with ~9M images for 600 object classes that have been annotated with image-level labels and object bounding boxes.More details about OIDv4 can be read from here.
The OIDv4 Toolkit is easy to use repo allows you to download only the image categories you need, along with their bounding boxes. This is public at https://github.com/EscVM/OIDv4_ToolKit
The problem is that the difference between the label format in Open Images Dataset and the input format of Yolo model makes it a bit difficult and takes a long time to standardize.
In this repository, I have customized and added a few features to easily standardize all data labels. It make easier to use custom data from Open Images Dataset for retraining the YOLO model.
I used main code from https://github.com/AlexeyAB/darknet and https://github.com/EscVM/OIDv4_ToolKit.
I also give a tutorial to train YOLOv4 on google colab with this repository and custom data.

II. Training Yolo_v4 with custom data by Google colab

1. Setup google colab

Check GPU

!nvidia-smi

Sun May 10 07:04:58 2020       
+-----------------------------------------------------------------------------+
| NVIDIA-SMI 440.82       Driver Version: 418.67       CUDA Version: 10.1     |
|-------------------------------+----------------------+----------------------+
| GPU  Name        Persistence-M| Bus-Id        Disp.A | Volatile Uncorr. ECC |
| Fan  Temp  Perf  Pwr:Usage/Cap|         Memory-Usage | GPU-Util  Compute M. |
|===============================+======================+======================|
|   0  Tesla T4            Off  | 00000000:00:04.0 Off |                    0 |
| N/A   65C    P8    12W /  70W |      0MiB / 15079MiB |      0%      Default |
+-------------------------------+----------------------+----------------------+
                                                                               
+-----------------------------------------------------------------------------+
| Processes:                                                       GPU Memory |
|  GPU       PID   Type   Process name                             Usage      |
|=============================================================================|
|  No running processes found                                                 |
+-----------------------------------------------------------------------------+

Clone this repository

!git clone https://github.com/DucLeTrong/YOLOv4_with_OpenImagesV4_GoogleColab.git

2. Download data

Install the required packages

Peek inside the requirements file if you have everything already installed. Most of the dependencies are common libraries.

%cd /content/YOLOv4_with_OpenImagesV4_GoogleColab/OIDv4_ToolKit
!pip3 install -r requirements.txt

Download different classes in separated folders

The ToolKit can be used to download classes in separated folders. The argument --classes accepts a list of classes or the path to the file.txt.

In this example download Person and Car from the train set. In this case we have to use the following command.

Read more about OIDv4_ToolKit here

 !python3 main.py downloader -y --classes Person Car --type_csv train --limit 100

�[92m
		   ___   _____  ______            _    _    
		 .'   `.|_   _||_   _ `.         | |  | |   
		/  .-.  \ | |    | | `. \ _   __ | |__| |_  
		| |   | | | |    | |  | |[ \ [  ]|____   _| 
		\  `-'  /_| |_  _| |_.' / \ \/ /     _| |_  
		 `.___.'|_____||______.'   \__/     |_____|
	�[0m
�[92m
             _____                    _                 _             
            (____ \                  | |               | |            
             _   \ \ ___  _ _ _ ____ | | ___   ____  _ | | ____  ____ 
            | |   | / _ \| | | |  _ \| |/ _ \ / _  |/ || |/ _  )/ ___)
            | |__/ / |_| | | | | | | | | |_| ( ( | ( (_| ( (/ /| |    
            |_____/ \___/ \____|_| |_|_|\___/ \_||_|\____|\____)_|    
                                                          
        �[0m
    [INFO] | Downloading Person.�[0m

�[95mPerson�[0m
    [INFO] | Downloading train images.�[0m
    [INFO] | [INFO] Found 248384 online images for train.�[0m
    [INFO] | Limiting to 100 images.�[0m
    [INFO] | Download of 100 images in train.�[0m
100% 100/100 [01:02<00:00,  1.59it/s]
    [INFO] | Done!�[0m
    [INFO] | Creating labels for Person of train.�[0m
    [INFO] | Labels creation completed.�[0m
    [INFO] | Downloading Car.�[0m

�[95mCar�[0m
    [INFO] | Downloading train images.�[0m
    [INFO] | [INFO] Found 89465 online images for train.�[0m
    [INFO] | Limiting to 100 images.�[0m
    [INFO] | Download of 100 images in train.�[0m
100% 100/100 [00:57<00:00,  1.73it/s]
    [INFO] | Done!�[0m
    [INFO] | Creating labels for Car of train.�[0m
    [INFO] | Labels creation completed.�[0m

3. Prepare data for Yolo formatting

Making obj_name.txt file contain all classes

%cd /content/YOLOv4_with_OpenImagesV4_GoogleColab

!echo Person >> obj_name.txt
!echo Car >> obj_name.txt

/content/YOLOv4_with_OpenImagesV4_GoogleColab

Processing data to yolo formatting and preparing training data with process_data.py

!python3 process_data.py --data_set_name='Train' --des_path='custom_data'

4. Config model

Mount google drive and create a symbolic link backup file at google drive to save training weight in case of training interruption with internet problems.

from google.colab import drive
drive.mount('/content/drive')

Go to this URL in a browser: https://accounts.google.com/o/oauth2/auth?client_id=947318989803-6bn6qk8qdgf4n4g3pfee6491hc0brc4i.apps.googleusercontent.com&redirect_uri=urn%3aietf%3awg%3aoauth%3a2.0%3aoob&response_type=code&scope=email%20https%3a%2f%2fwww.googleapis.com%2fauth%2fdocs.test%20https%3a%2f%2fwww.googleapis.com%2fauth%2fdrive%20https%3a%2f%2fwww.googleapis.com%2fauth%2fdrive.photos.readonly%20https%3a%2f%2fwww.googleapis.com%2fauth%2fpeopleapi.readonly

Enter your authorization code:
··········
Mounted at /content/drive

!ln -s "/content/drive/My Drive/backup_yolo" "/content/YOLOv4_with_OpenImagesV4_GoogleColab"

I created a text file named it 'config_data.txt' containing the following:

classes is '2' as number of classes training.
train.txt is a single text file that lists the full directory of where each photo is that you downloaded; I created it by runing process_data.py
test.txt; same as above and this is created along with the train.txt file.
"backup_yolo" is just a folder where you want the trained weights files to be output to while it trains.

# Create config_data.txt config file
!rm -rf config_data.txt
!echo classes=2 > config_data.txt
!echo train=train.txt >> config_data.txt
!echo valid=test.txt >> config_data.txt
!echo names=obj_name.txt >> config_data.txt
!echo backup=backup_yolo >> config_data.txt

Compile Darknet (using cmake)

!chmod +x ./build.sh
!./build.sh

[100%] �[32m�[1mLinking CXX executable uselib�[0m
[100%] Built target uselib
�[36mInstall the project...�[0m
-- Install configuration: "Release"
-- Installing: /content/Train-YOLOv4-with-OpenImagesV4-Colab/libdark.so
-- Installing: /content/Train-YOLOv4-with-OpenImagesV4-Colab/include/darknet/darknet.h
-- Installing: /content/Train-YOLOv4-with-OpenImagesV4-Colab/include/darknet/yolo_v2_class.hpp
-- Installing: /content/Train-YOLOv4-with-OpenImagesV4-Colab/uselib
-- Set runtime path of "/content/Train-YOLOv4-with-OpenImagesV4-Colab/uselib" to ""
-- Installing: /content/Train-YOLOv4-with-OpenImagesV4-Colab/darknet
-- Installing: /content/Train-YOLOv4-with-OpenImagesV4-Colab/share/darknet/DarknetTargets.cmake
-- Installing: /content/Train-YOLOv4-with-OpenImagesV4-Colab/share/darknet/DarknetTargets-release.cmake
-- Installing: /content/Train-YOLOv4-with-OpenImagesV4-Colab/share/darknet/DarknetConfig.cmake
-- Installing: /content/Train-YOLOv4-with-OpenImagesV4-Colab/share/darknet/DarknetConfigVersion.cmake

Download weights of YoloV4 pretrain from google drive

import gdown
url = 'https://drive.google.com/uc?id=1JKF-bdIklxOOVy-2Cr5qdvjgGpmGfcbp&export=download'
output = 'yolov4.conv.137'
gdown.download(url, output, quiet=False)

Downloading...
From: https://drive.google.com/uc?id=1JKF-bdIklxOOVy-2Cr5qdvjgGpmGfcbp&export=download
To: /content/YOLOv4_with_OpenImagesV4_GoogleColab/yolov4.conv.137
170MB [00:03, 44.3MB/s]

'yolov4.conv.137'

Customize model config file

Copy config file

!cp cfg/yolov4-custom.cfg yolov4-custom.txt

Edit yolov4-custom.txt file as follows:

Line 3: Set batch=64.
Line 4: Set subdivisions=32, the batch will be divided by 16 or 64 depends on GPU VRAM requirements.
Change line max_batches to classes*2000 but not less than number of training images, and not less than 6000, f.e. max_batches=6000 if you train for 3 classes.
Change line steps to 80% and 90% of max_batches, f.e. steps=4800,5400.
Change line classes=2 to your number of objects in each of 3: Line 970 1058 1146.
Change [filters=255] to filters=(classes + 5)x3 in the 3 [convolutional] before each [yolo] layer, keep in mind that it only has to be the last [convolutional] before each of the [yolo] layers. Line 1139 1051 963. In this case, filters=(2 + 5)x3

Save that after making the changes.

5. Train Model

!chmod +x ./darknet
!./darknet detector train config_data.txt yolov4-custom.txt yolov4.conv.137 -dont_show > yolov3-5c.log

 CUDA-version: 10010 (10010), cuDNN: 7.6.5, CUDNN_HALF=1, GPU count: 1  
 OpenCV version: 3.2.0
 0 : compute_capability = 750, cudnn_half = 1, GPU: Tesla T4 
   layer   filters  size/strd(dil)      input                output
   0 conv     32       3 x 3/ 1    608 x 608 x   3 ->  608 x 608 x  32 0.639 BF
   1 conv     64       3 x 3/ 2    608 x 608 x  32 ->  304 x 304 x  64 3.407 BF
   2 conv     64       1 x 1/ 1    304 x 304 x  64 ->  304 x 304 x  64 0.757 BF
   3 route  1 		                           ->  304 x 304 x  64 
   4 conv     64       1 x 1/ 1    304 x 304 x  64 ->  304 x 304 x  64 0.757 BF
   5 conv     32       1 x 1/ 1    304 x 304 x  64 ->  304 x 304 x  32 0.379 BF
   6 conv     64       3 x 3/ 1    304 x 304 x  32 ->  304 x 304 x  64 3.407 BF
   7 Shortcut Layer: 4,  wt = 0, wn = 0, outputs: 304 x 304 x  64 0.006 BF
   8 conv     64       1 x 1/ 1    304 x 304 x  64 ->  304 x 304 x  64 0.757 BF
   9 route  8 2 	                           ->  304 x 304 x 128

DucLeTrong/YOLOv4_with_OpenImagesV4_GoogleColab