# Machine Learning Techniques in the Sound Design for Later Stage of Film Based on Computer Intelligence

Authors: Tian Zhang
Journal: Security and Communication Networks
 (2022)

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## Abstract

This study analyses the connotation of sound design in the later stages of the film and how to grasp the truth of art under subjective creative thinking in order to improve the effect of sound design in the later stages of the film and then proposes multiple methods of sound element selection and organisation, as well as sound element combination modes, in order to improve the effect of sound design in the later stages of the film. Furthermore, in the final stages of the film, this study incorporates digital and intelligent technologies to create a sound design system. Furthermore, in the final stages of the film, this study examines a number of technologies and picks the right sound design. Finally, this article blends experimental research with system performance analysis. The sound design system based on computer intelligence suggested in this study has a specific influence, as shown by the experimental investigation.


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## Body

## 1. Introduction

Sound design refers to the overall design of the sound part of the entire program or film (including language sound, music sound, and effect sound) in the production of visual media, so that sound and other artistic methods can work together to complete the work of shaping the artistic image. According to the overall artistic concept of the program or film, sound designers plan and design the sound composition and recording method of the program or film and organize the implementation, recording, and synthesis of the program [1].In the field of sound design, it can be divided into two categories: films and games. Film sound is currently the most mature sound design industry. Due to the prosperous development of the film itself, its software and hardware technologies will undergo continuous changes in the years to come [2].In sound design, the term “sound” may refer to any aspect connected to hearing in visual media, such as music, sound effects, and conversation. It mainly refers to sound effects in visual media in a restricted sense. The article’s suggested idea of “sound design” is examined in its broadest sense. The goal of this study is to examine the similarities and contrasts of sound design in visual media (films and games) by describing the production process of the author’s two sound design works [3].Sound is our study object in the development of cinema sound art, and it covers a broad variety of topics, including objective physical qualities of sound, subjective physiological reactions, and psychological affects, as well as the complicated research scope of audio-visual interaction. Film sound is first of all sound, and the study of sound should focus on its “nature” first. The characteristics of sound are of great significance to the selection and combination of sound elements in postproduction. Only when the sound engineer is familiar with the “physical properties” of the sound, his creation can have a basis and a relatively good foundation for creation. When the sound engineer fully understands the reasonable characteristics of the sound of the film and deeply understands the inner feelings of the viewers, he can use creativity and technology to actively and effectively select and combine sounds to form the auditory art system of the film and enhance the artistic charm of film sound [4].From the perspective of physics, the film is a “wave” art, which is made up of light waves and sound waves. Among them, sound is a kind of mechanical wave, called a sound wave, which is caused by vibration. The frequency, amplitude, and period of vibration fundamentally determine the nature of the wave. Sound transfers energy in the medium in the form of waves. In a unit time, the greater the sound energy passing through a unit area perpendicular to the sound propagation direction, the stronger the sound intensity. The transmitted energy determines the intensity of the sound. The equal loudness curves obtained by Fletcher and Monsen from experiments reveal that different frequencies of sounds require different sound levels when they are equally loud.Sound propagates in the medium with a certain direction of movement and its independence. Under certain conditions, sound waves will produce reflection, interference, and diffraction phenomena. From the analysis of objective physical properties, the frequency and frequency combination of vibration are transmitted to people in the form of waves. The frequency, frequency spectrum, and propagation properties of the vibration define the pitch and timbre of the sound that humans hear. Paying close attention to the physical features of sound components and the law of propagation is the foundation for actively and successfully choosing and mixing sounds to satisfy artistic expectations in the latter stages of the film’s sound design. This study combines computer intelligence technology to study the sound design in the later stage of the film and build an intelligent system to improve the effect of sound design in the later stage of the film and enhance the degree of film viewing.


## 2. Related Work

In the digital age, scholars have asserted that digitization will completely change the traditional classic films, form a new film language, and show the unique charm of digital film art. There are many research monographs on digital technology. Through the analysis of digital film production and digital film special effects, literature [5] expressed the influence of virtual reality created by digital technology and real virtuality on film concepts. Literature [6] introduced in detail the collection, editing, artistic conception, and comprehensive processing skills of digital audio technology for film and television sound. Literature [7] summarized the media theory of image technology and tried to analyze the change of image technology and film media form, the change of digital film media form under the concept of digital film aesthetics, and the digital prospect of intelligent development. Literature [8] examined the effects of digital technology on visual culture and movie-watching experiences, as well as the pictures and rerecognition of its imaging. The new technology of digital special effects in cinema, as well as the interactive and real-world system of film introduced by the new technology, was detailed in literature [9]. Literature [10] described the manufacturing technique and picture properties of holographic films and 3D films, emphasising that the objective of cinema and television development is to achieve full three-dimensional image projection. Literature [11] documented the recent evolution of new film technologies. It discussed the new evolution of movies brought on by high resolution, high frame rate, dynamic range increase, and colour gamut extension, as well as the future trend of virtual technology in movies. With the continuous development of science and technology in these years, signal analysis equipment has been continuously updated, and dynamic signal analyzers have also been continuously developed in a highly integrated, portable, and real-time direction. At the same time, dynamic signal analyzers are also developing. Signal analysis, vibration detection, fault diagnosis, and other directions have been widely used [12]. Denmark, Belgium, France, and other European countries have also developed them one after another, for example, the SR785 dynamic signal analyzer of Stanford Corporation in the United States. This type of analyzer is a dual-channel 100 kHz dynamic signal analyzer with a dynamic range of 90 dB. The two test channels of SR785 can perform data detection independently, and each test channel can independently set the corresponding acquisition parameters to make it meet the corresponding test environment and test requirements. At the same time, it can also detect the coherence of the signal and other signal performance of the two channels. A low-distortion signal source is also embedded in the SR785 dynamic signal analyzer of Stanford Company, which can test the signal tracking function. The instrument communicates with the host computer through the RS232 serial port. Although the SR785 has powerful functions, due to its early development time, the internal components used are also relatively low end. With the continuous improvement of signal acquisition requirements for dynamic signal analysis equipment, the SR785 has a relatively small number of channels and a relatively obsolete system architecture. The dynamic range is relatively small, the volume of the equipment is relatively large, the shortcomings of not being portable are exposed, and it is difficult to meet the current test requirements [13]. The United Kingdom has also developed a dynamic signal analysis equipment PL202 with more advanced performance. The dynamic signal analyzer of the PL202 model is also a dual channel and can also work independently on a single channel. When it works in dual channels, the signal analysis bandwidth reaches 40 kHz. When a single channel works independently, the signal analysis bandwidth of each channel reaches 10 kHz. The dynamic signal analyzer contains a 1 M memory card inside for data storage. The PL202 has a functional dynamic range of 70 dB and interfaces with the host computer through RS232. However, the PL202 dynamic signal analyzer’s circuit design and system architecture are relatively obsolete, which makes subsequent maintenance and usage problematic, and the instrument’s performance is not enhanced, making it impossible to satisfy today’s sophisticated test environment [14]. The United States has produced modular dynamic signal analysis equipment, such as NI’s PCI-4461 dynamic signal analyzer, as a part of the ongoing improvement of electronics. PCI-4461 is a kind of dynamic signal analysis equipment composed of designing the acquisition board, embedding the acquisition board into the industrial computer, and supporting the analysis and processing software of the upper computer. The product of this architecture has a very large performance improvement over the Agilent 35670A, the dynamic range exceeds 100 dB, and the highest sampling rate reaches 102.4 kSa/s. But it is inconvenient to carry and test on-site. Moreover, the development cost of upper management software is also very high [15]. Although portable dynamic signal analyzers are successively listed abroad, their functions are relatively single, and their performance cannot meet the complex test requirements, so the application range is not very wide [16].


## 3. Film Sound Production Algorithm

ut represents the current frame of the movie audio sequence at time t, utx represents a certain point x in ut, its matching point in the previous frame ut−1 is ut−1x−1, and the matching point in the next frame is ut+1x+. Point x moves within a certain neighborhood range N0, y is the moving distance, and then the pixel difference between utx+y and ut−1x−+y after moving can be expressed as follows:(1)d−=utx+y−ut−1x−+y.Among them,y∈N0. When y takes different values, different d− can be obtained. From the literature, these values are independently distributed random variables and obey Gaussian distribution N0,σX2. In the same way, all d+ can be found.For any pointx, the average difference in gray level can be calculated according to the following formula [17]:(2)Dx−=1M∑i=1Mdi−.Among them,M represents the total number of audio frames in the range N0. According to the basic principles of probability theory, Dx− should obey the Gaussian distribution N0,σX2/M. The same method can be used to obtain Dx+, and the area of the tails at both ends of the Gaussian distribution can be calculated using the formula [18]:(3)FXδ=1−M2πσX2∫−δ+δe−Ms2/2σX2ds.Among them,σX represents the local standard deviation, which reflects the degree to which the pixel difference Dx− (or Dx+) deviates from 0. For any audio frame x, if the calculated FXDx− and FXDx+ are very small, and the observed Dx− and Dx+ will be very large at this time, then it can be considered that the obtained gray level difference does not satisfy the local statistical characteristics between frames. If Dx− and Dx+ have the same sign at the same time, then it can be considered that there is a spot at the audio frame x. On the contrary, it indicates that the corresponding point between the point and the previous frame and the next frame is a normal gray-scale gradual process. For this reason, the adaptive blob detection index in this study is defined as follows:(4)AXDIx=maxFXDx−,FXDx+×signDx−×Dx+.In practical applications, a thresholdε can be set for the current frame ut, 0<ε<1. For any point x in ut, if its detection index satisfies the relationship 0<ASDIx<ε, then it can be considered that there is a spot at the audio frame x.The threshold size is crucial in defining the impact of spot detection. If the threshold is set too high, the detection result will include a significant number of false detection points, and vice versa, it will result in genuine spot missed detection. The standard technique, which lacks flexibility, employs the same threshold for all frames. However, to guarantee that each frame of sound has the optimum spot detection impact, this work uses iterative and convergent approaches. The specific method is to first set a small initial thresholdε0, 0<ε0<1. At this time, only a small number of spots should be detected, and the detection result is M0, the connected spots in the detection result are marked, and the number of spot blocks is recorded as n0. The current threshold is increased by a preset iteration step length Δε, the detection is performed again, and the detection result is recorded as M1. Similarly, the connected blobs in the detection result are marked, and the number n1 of blobs is recorded [19].Ifn0≠n1, then it means that no new spots appear after the threshold is increased, and the spot area has expanded, as shown in Figures 1(a) and 1(b). At this point, it is a process, in which the spot detection result tends to be complete, M0=M1, and it is continued to be iterated. If n0≠n1, then it means that after the threshold is increased, there are new spots in the detection results that are not connected to the original detection results, such as areas 3 and 4 marked by ellipses in Figure 1(c). At this time, further discrimination is required. If the following judgment conditions are met, it indicates that the newly added area is a real spot area and should be retained. Otherwise, it is judged to be a pseudo spot, then it is removed, the detection result in M1 is screened and reassigned to M0, and the iteration is continued. Until the newly added spot area to be verified does not meet the judgment condition, the iteration is stopped, and the last detection result is taken as the final detection result.Figure 1
Threshold iteration process. (a) Original spot map. (b) Spot enlarged map. (c) New spot map.
(a)(b)(c)Due to the temporal discontinuity and spatial consistency of the spots, the judgment conditions for a certain spot areaS0 to be verified can be summarized as follows: (1)
The spot area to be verified and the corresponding areas of the two frames before and after have obvious gray-level differences, according to the formula (2) [20]:(5)b−=1N∑i,j∈S0zti,j−zt−1i,j,b+=1N∑i,j∈S0zti,j−zt+1i,j,CS0=minb−,b+⋅signb−⋅b+.For a given positive numberα, if CS0 > α, then it is considered that condition 1 is satisfied.(2)
The gray value of the pixel in the spot area to be verified is relatively smooth; that is, there is no obvious difference in the gray value of the pixel in the area. The calculation is as follows:(6)σ2S0=1N∑i,j∈S0zti,j−z¯2.For a given positive numberβ, if σ2S0<β, then it is considered that condition 2 is satisfied. Among them, zti,j represents the pixel value of a certain point in the spot area to be verified, zt−1i,j and zt+1i,j represent the pixel value of the corresponding point of the point in the previous frame and the next frame, respectively, z¯ represents the average gray value of the pixel in the area, and z represents the number of audio frames in the area. If the spot area S0 to be verified satisfies the above two conditions at the same time, then it is considered that the area is a spot, and the area needs to be retained; otherwise, the area is removed.Motion estimate is the initial stage of a patch detection technique based on numerous frames, and the outcome of its processing has a direct impact on the patch detection algorithm’s effect, thus it is crucial. Effective motion estimation can ensure that sound information corresponds correctly across subsequent frames and that mutation damage information from the present frame is accurately detected. The block matching approach is used in this research to estimate motion. The specific algorithm has been described in Section 2, and we will not repeat it in this section. For any matching blockW in the current frame ut, W− represents its best matching block in the previous frame ut=1, and W+ represents its best matching block in the next frame ut+1. The block matching criterion is defined as follows [21]:(7)dW−,W=∑i=0p−1∑j=0q−1fx+i,y+j−fm+i,n+j,W−=argmindW−,W.In the formula, (x, y) and (m, n) are the pixel coordinates of the upper left corner of W− and W, respectively and p and q represent the number of pixels in the horizontal and vertical directions of the macroblock. The same method can be used to find W+.The local standard deviationσx reflects the degree of deviation of the pixel difference Dx− (or Dx+). The smaller σx is, the closer Dx− (or Dx+) is to 0. That is, for a certain audio frame x in the current frame, the gray value difference between its neighboring block and the matching block in the previous frame (or the next frame) is smaller. Since the standard deviation of the difference between pixel W− and pixel W can reflect the degree of pixel difference in the corresponding regions in the two frames before and after, the standard deviation of the difference between pixel W− and pixel W can be used as an empirical estimate of the standard deviation σx. At this time, different macroblocks in a frame of sound will produce different local standard deviations, which can be used to detect audio frames in the macroblock area respectively [22].The sound design system is constructed in the later stage of the film.The microphone array signal processing system is made up of the microphone array construction, signal acquisition system, and microphone array signal processing algorithm. The overall procedure of the most typical microphone array employed in the sound source localization system at this stage is shown in Figure2. The sound source is sampled using microphones at predefined places in the microphone array, and the signal acquisition system sends important information to the terminal device, such as the sampled signal of each microphone. Through the related algorithm of microphone array sound source positioning, the position information of the sound source relative to the microphone array is calculated, so as to realize the localization of the target sound source.Figure 2
The process of microphone array sound source positioning.According to the distance between the target sound source and the microphone array, the sound field can be divided into near-field sound source models and far-field sound source models. The near-field model treats sound waves as spherical waves, and the far-field model treats sound waves as plane waves. In comparison, the angle far-field models of the sound source signals received by the microphones in the array are relatively close, while the near-field models are quite different, as shown in Figure3.Figure 3
Schematic diagram of the far-field model and the near-field model. (a) Near-field model: spherical wave. (b) Far-field model: plane wave.
(a)(b)Figure4 is a model of a microphone array receiving a far-field sound source. In the figure, k represents the wave number of the incident wave, and κ is the direction of the incident wave and its value is a unit vector. The microphone array is a set of M uniformly arranged linear microphones.Figure 4
Schematic diagram of far-field microphone signal receiving model.The advantages of multiarray positioning information fusion are as follows: (1) it improves the accuracy and comprehensiveness of positioning information and obtains more accurate and comprehensive positioning information than a single array. (2) It reduces the uncertainty of positioning information. The sound source positioning information obtained by multiple microphone arrays is complementary, which can compensate for the uncertainty of certain single-array positioning and the limitations of the measurement range. (3) It improves the reliability of the positioning system. When one or several arrays fail, the positioning system can still operate normally, increasing the real-time performance of the system. The multiarray positioning information fusion processing model mainly includes two systems: (a) centralized fusion system and (b) distributed fusion system. The centralized fusion system uses the information of all single-array sound source positioning systems to estimate the sound source position and predict the calculation All the position data measured by the single-array sound source positioning system are sent to a central site for Kalman filter processing to obtain the final sound source position.The centralized fusion system processing is shown in Figure5.Figure 5
The processing block diagram of the centralized fusion system.The advantage of this method is that it involves minimal loss of positioning information. However, it will cause a serious computational burden. Because when serious data errors occur, the entire centralized fusion system may become unreliable due to poor accuracy and stability. The location estimate data provided by each single-array sound source positioning system are Kalman filtered by the distributed fusion system. The location estimate data acquired from each individual array are then sent to the data fusion centre for fusion in order to achieve the final sound source localization result. The processing block diagram of the distributed fusion system is shown in Figure6.Figure 6
The processing block diagram of the distributed fusion system.The distributed fusion system is more in line with the multi-array joint positioning algorithm discussed in this study. The Kalman filtering method is used to filter the estimated sound source position of each single array sound source positioning system. The processed data will include an estimate of the sound source location data from the prior and subsequent times, allowing for the filtering of position data with wide differences between the estimated and actual measured values. The Kalman filter may also efficiently filter the location data collected by each single-array sound source positioning system since it is expected that the sound is continuous within a restricted observation duration.The system designed in this subject combines the two digital technologies of algorithmic composition and interactive design. Moreover, while the computer is autonomous, intelligent, and digitized, it uses interactive means to interfere with a large number of variable parameters in the algorithm, thereby adding human subjective initiative to the algorithm and guiding the development of music by way of object feedback without destroying the autonomy of computer digital processing. Its working principle is shown in Figure7.Figure 7
Intelligent sound design system in the later stage of the film.


## 4. The Effect Verification of Sound Design System in the Later Stage of the Film Based on Computer Intelligence

This study combines multiple technologies to construct the sound design system in the later stage of the film and analyzes multiple technologies to select the appropriate sound design in the later stage of the film technology. After constructing the sound design system in the later stage of the film based on computer intelligence, the performance of the system is verified and the system performance from the sound design in the later stage of the film requirements is verified. This study mainly evaluates the digital effect of sound in the later stage of the film and the sound design effect of the later stage of the film. This study conducts research through simulation experiments and analyzes the results with expert evaluation methods. The results are shown in Tables1 and 2 and Figure 8.Table 1
Statistical table of the digital effect of the sound in the later stage of the film.
No.DigitizingNo.DigitizingNo.Digitizing193.13084.55993.8288.13190.26091.3393.93290.26194.5483.53389.26285.4584.13493.66382.8691.83587.56482.9786.73691.86593.3890.53787.06692.8993.73889.56791.51086.73992.66885.71190.64084.06988.91293.24190.07093.91382.64290.07193.01492.94393.57284.41588.84488.47393.81690.74585.67489.81786.04687.27589.81895.04793.27692.11990.44882.47789.12087.14988.47883.42186.45083.87994.92292.25186.58084.32394.35293.18192.52485.55390.78282.62584.35489.68382.12694.65584.78486.82790.85688.18585.52890.65787.08691.72988.95888.38789.9Table 2
Statistical table of the design effect of the sound in the later stage of the film.
No.Design effectNo.Design effectNo.Design effect180.23089.15986.4288.53188.86089.7382.93289.06180.0488.83385.66290.1580.93484.76385.2686.13588.76490.3780.33687.06579.8884.83782.46689.5984.73879.56789.61090.63990.86881.91180.04083.66980.41287.14183.77090.51386.64288.27184.91489.64383.27282.61584.84487.37381.01682.64579.97488.31779.54684.67587.21880.94786.57685.41984.04890.77785.82087.54988.47890.12183.35091.07989.72289.45184.08081.92389.35288.28189.42485.45383.48286.42584.15486.48381.52689.15585.38489.02780.65680.28588.12889.95787.48689.82982.75883.28786.2Figure 8
Statistical diagram of the digital effect of the sound in the later stage of the film.From the above experimental research, we can see that the sound design system in the later stage of the film based on computer intelligence proposed in this study has certain effects, and the system in this study can be used in the subsequent film sound production.


## 5. Conclusion

The film’s final stages provide plenty of room for filmmakers, composers, and sound engineers to express themselves. This study examines the meaning of sound design in the film’s latter stages and how to understand the reality of art while engaging in subjective creative thought. Then, using empirical analysis, this study presents the mode, structure, and law of the sound element combination of multiple methods of sound element selection and organisation and sorts out a set of knowledge systems with certain theoretical guiding significance and certain practical operation value. The selection and arrangement of cinema sound components will overcome blindness, be more proactive, and be more productive within the framework of this knowledge system. This study combines digital technology and intelligent technology to construct a sound design in the later stage of the film system and combines multiple technologies to construct a sound design in the later stage of the film system. Moreover, this study analyzes a variety of technologies and selects the appropriate sound design technology in the later stage of the film. In addition, this study combines experimental research to analyze the performance of the system constructed in this study. It can be seen from the experimental research that the sound design system in the later stage of the film based on computer intelligence proposed in this study has a certain effect.



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