## 1 Introduction  
Currently, video material uploaded to an Internet service can be very easily and quickly downloaded and then published further without the knowledge and consent of the author or the rights' holder. Of course, there are many types and cases of copyright infringement; however, the description of this phenomenon is not the purpose of this publication. In view of this phenomenon, the protection of intellectual property in the digital field is an important aspect of today's social life. To secure the rights to a video, a visible watermark is applied to the video for subsequent identification [1, 2]. Despite the simplicity and effectiveness of this solution, the method has the significant disadvantage of leaving a visible mark on the entire video, which may affect its reception by the viewer of the video, and it also informs a person who is potentially interested in the unauthorised downloading and publication of the video about the security of the video. Potential infringers will not be discouraged by visible watermark information as there are methods available for the removal of visible watermarks. Due to the above-mentioned drawbacks of the solution for the protection of intellectual rights with a visible watermark, a watermark transparent to the human eye has been introduced, which leaves the reception by the target viewer undisturbed by redundant graphic information. Moreover, a potential copyright infringer may not be aware of the fact that the video material is protected [3, 4]. However, it should be acknowledged that there are specialised methods designed to detect transparently embedded watermarks [5, 6]; moreover, there are methods for attempting to remove such watermarks [7, 8]. With the development of the issue of embedding a transparent watermark, there has been a demand for the development of new ways of embedding a watermark in a video. There are different methods for embedding a watermark in a video based on conventional methods, such as the discrete wavelet transform [9], the use of the least significant bit [10], and others mentioned later in this article; however, this article presents an approach that uses deep neural networks (DNNs) for this task. The methods outlined in the previous sentence are designed to embed a transparent watermark with the greatest possible capacity and resistance to distortion. There are many papers in the literature dealing with video watermarking using artificial neural networks (ANNs) [11; 12]. Among the works describing the process of embedding a watermark in a video, there are works dedicated specifically to a particular video codec, such as H.264/AVC (Advanced Video Coding) [13; 14] and its successor H.265/HEVC (High-Efficiency Video Coding) [15; 16]. Methods based on the use of ANNs, as well as classical methods, have their advantages and disadvantages in their applications, and they have the potential to be further improved. In this paper, the solution is based on the use of DNNs because neural networks are able to predict and find features of the problem under study that a creator of handwritten algorithms cannot predict; therefore, algorithms operating on deep networks are better-suited to solving various, highly complex problems. The necessary condition for such a statement is the assumption that a properly designed neural network architecture is selected and that it has an optimal training set. The aim of this article is to introduce a robust watermarking method based on the use of DNNs with the adjustable subsquares properties encoding data algorithm dedicated to high-quality video compressed by HEVC codec. The main problem to overcome is assuring the survival of the watermark when the embedded frames are passed through the HEVC codec compression channel. It is a demanding task to embed a watermark and provide its resistance to compression channels in a way that does not degrade the visual quality of the video.