KR20100131735A - A video quality monitoring method and apparatus - Google Patents

Abstract

PURPOSE: A video quality monitoring method and a device thereof are provided to measure deterioration of picture quality for an image played in a settop box. CONSTITUTION: A receiving unit(510) receives a VR(Visual Rhythm)_Diff image from a settop box. A picture quality estimation value calculating unit(520) calculates an image quality estimation value by a frame. An image deterioration standard calculating unit(530) calculates a deterioration number, a threshold deterioration number, a threshold deterioration rate, an average deterioration amount, and an average threshold deterioration amount. A sensory image quality calculating unit(540) calculates subjective picture quality from VR information.

Description

Video quality monitoring method and device {A VIDEO QUALITY MONITORING METHOD AND APPARATUS}

The present invention relates to a method and apparatus for monitoring image quality, and more particularly, to a method and apparatus for monitoring image quality deterioration for an image reproduced in a set-top box.

Recently, with the commercialization of IPTV, interest in image quality has sharply increased. In this regard, IPTV operators are making various efforts to monitor the level of image quality experienced by the viewers and to reflect the results in the content generation or transmission methods to increase customer satisfaction. How to evaluate

Currently, ITU-T SG9 and VQEG are being standardized to measure the objective quality of subjective sensational quality, which is largely referred to as Full Reference (FR), Reduced Reference (RR), and No Standard (NR). ; No Reference).

Among these, the electro-observation method is a method of measuring the similarity or distortion of the reproduced image compared to the original image. In addition, the reduction criterion method is a method of measuring the relative image quality by comparing the feature information extracted from the original image and the feature information extracted from the playback image, the non-reference method is only a playback image visible to the viewer in the absence of the original image itself or feature information How to measure the quality.

Of these, the Electro-Compliance provides the most accurate results, and the Non-Standard Law is known to be the most inaccurate.

However, in the actual IPTV business, there are many factors that affect the quality of the playback video. Therefore, the relative comparison between the original and the playback video suggested by the above standard can cope with the problems such as the deterioration of the quality in the IPTV business. Difficult to do

For example, the distortion of the encoded image, i.e., the distortion at the front-end stage, is mainly due to the defect of the original image or the distortion introduced during the encoding process, and the distortion due to a defect in a network or a set-top box. That is, since the distortion at the back-end is mainly caused by packet loss or malfunction of the set-top box, the distortion at the front-end and the distortion at the back-end are different from each other.

Therefore, since the playback image of the set-top box represented on the viewer's TV appears as the sum of all distortions, it is difficult to find the cause when the distortion occurs.

Therefore, J.240 (Framework for remote monitoring of transmitted picture signal-to-noise ratio using spread-spectrum and orthogonal transform), standardized in June 2004 by ITU-T, divides the input image into blocks of appropriate size. We proposed a method that randomizes image data in frequency domain or spatial domain using spread spectrum and orthogonal transform and takes one sample as feature information. It is claimed that the estimated mean of the Peak Signal-to-Noise Ratio (hereinafter referred to as PSNR) is very accurate.

However, this method requires an operation that requires multiplying image data by a pseudo-noise (PN) sequence and performing Walsh-Hadamard transformation to extract feature information. Although this operation is not very expensive, it is very burdensome to process in the set-top box because the operation must be performed on all pixel information, and the PSNR value estimated at the individual frame level may be different from the claim.

For example, a 720x480 @ 30 fps video requires 1,296kbps of bandwidth required by feature information, which is very burdensome to process in a set-top box.

Also proposed by YAMADA et al (“Reduced-reference based video quality metrics using representative-luminance values,” in Proc. International Workshop on Video Processing and Quality Metrics for Consumer Electronics, Scottsdale, Ariz., USA, Jan. 2007.) The method estimates the PSNR by transmitting the position of the pixels having the "representative luminance value" in the input image and the value as the characteristic information, and extracting and comparing the pixel values of this position as the characteristic information at the receiving side.

Although this method is simple, the location information of the "representative luminance value" involves a large amount of data, and in order to make it practical, a separate binary compression codec for compressing the location information is required.

Therefore, there is a need for a method of quantitatively measuring the quality of the image reproduced in the set-top box while minimizing the computational burden of the set-top box and easily identifying various information on the deterioration of image quality of the reproduced image.

In order to solve the above-mentioned problems of the prior art, the present invention provides a new quality measure for measuring the degree of image quality deterioration and a quality deterioration measure based thereon.

In addition, the present invention provides a method and apparatus for measuring image quality deterioration of an image reproduced in a set-top box while reducing the computational burden of the set-top box.

In addition, the present invention provides a method and apparatus for quantitatively measuring the quality of a playback image deteriorated due to packet loss and allowing a quality control operator to easily identify the location and amount of image quality deterioration.

The objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood from the following description.

In order to achieve the above object, a method for monitoring image quality according to an aspect of the present invention comprises the steps of (a) receiving, from a first server, the first visual rhythm information of an encoded image, (b) the encoded image Extracting second visual rhythm information on the decoded playback image received through a network, (c) calculating a visual rhythm difference based on the first visual rhythm information and the second visual rhythm information; and (d) transmitting the calculated visual rhythm difference to a second server, wherein the second server measures the deterioration of image quality of the reproduced image by using the visual rhythm difference.

In order to achieve the above object, a method for monitoring image quality according to another aspect of the present invention, (a) receiving from the media server, the first visual rhythm information for the encoded image, (b) from the set-top box Receiving second visual rhythm information on the decoded playback image, (c) calculating a visual rhythm difference based on the first visual rhythm information and the second visual rhythm information, and (d) Measuring deterioration of image quality of the reproduced image by using a rhythm difference.

In order to achieve the above object, the apparatus for monitoring the image quality according to an aspect of the present invention is the first visual rhythm information that is visual rhythm information for the encoded image from the set-top box and the visual for the image reproduced in the set-top box Receiving unit for receiving a visual rhythm difference using the difference of the second visual rhythm information that is rhythm information Image quality estimation value calculating unit for calculating the image quality estimation value of the image played in the set-top box using the visual rhythm difference image, the playback image The image quality deterioration scale calculation unit for calculating an image quality deterioration measure including at least one of a deterioration number of times, a threshold deterioration number, a threshold deterioration rate, an average threshold deterioration amount, and an average deterioration amount, and the image quality estimation value and the user's request. Graphical user interface providing image quality monitoring information based on quality deterioration measures It includes.

In order to achieve the above object, an apparatus for monitoring video quality according to another aspect of the present invention is a video decoder for decoding the encoded video received from the first server via a network to generate a playback video, a second from the playback video Visual rhythm information extraction unit for extracting the visual rhythm information, Visual rhythm difference calculation for calculating the visual rhythm difference based on the first visual rhythm information and the second visual rhythm information for the encoded image received from the first server And a visual rhythm difference transmitter for transmitting the visual rhythm difference to a second server that measures image quality deterioration for the reproduced image by using the visual rhythm difference.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG.

The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. It is provided to fully inform the owner of the scope of the invention.

According to one of the problem solving means of the method and apparatus for monitoring the image quality of the present invention described above, it is possible to measure the deterioration of the image quality of the image reproduced in the set-top box while reducing the computational burden of the set-top box.

In addition, since visual rhythm information is used, objective quality measurement such as position, duration, deterioration frequency, average deterioration amount of image quality deterioration with respect to the playback image is possible, and playback quality measurement by frame is also possible.

In addition, visual rhythm information can visually confirm the deterioration of image quality of the playback image, thereby enabling intuitive image quality monitoring.

In addition, by transmitting the compressed visual rhythm information and the compressed visual rhythm information difference image, it is possible to reduce the uplink transmission bandwidth, and contribute to securing the storage space.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention.

The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

For reference, in the entire specification, when a part is "connected" to another part, it is not only "directly connected" but also "electrically connected" with another element in between. Also includes.

Also, when an element is referred to as "comprising ", it means that it can include other elements as well, without departing from the other elements unless specifically stated otherwise.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

1 is a diagram illustrating a configuration of a system for monitoring video quality of an IPTV according to an embodiment of the present invention.

For reference, a system for monitoring video quality of an IPTV according to an embodiment of the present invention may be implemented in an on-line method and an off-line method, and hereinafter, divided into an online method and an offline method. This section describes the operation of each component of the system.

The system for monitoring video quality of an IPTV according to an embodiment of the present invention includes a media server 110, a set top box 120, and a quality management server 130.

First, referring to FIG. 1, each component in the online method will be described. The media server 110 includes a video encoder 111 and a visual rhythm information extractor 112.

Here, the video encoder 111 compresses the video signal. The media server 110 stores the video bit stream compressed by the video encoder 111 and transmits it to the set-top box 120 through a network.

In addition, the visual rhythm information extractor 112 extracts visual rhythm information (hereinafter, referred to as VR) from the video bit stream stored in the media server 110, that is, the encoded image (hereinafter, referred to as first VR information). Extract.

For reference, the VR information extracting unit 112 may include a PTS (Presentation Time Stamp) value, which is time information, and a program ID, which is an identifier for identifying content, in the first VR information.

Here, the VR information is composed of one-dimensional information by partially sampling the pixels of the two-dimensional image frame, and sampling the pixels at the same position for successive image frames on the time axis to project the three-dimensional image information into the two-dimensional information. As such, the detailed description of the VR information will be described later with reference to FIG. 3.

Thereafter, the media server 110 stores the generated first VR information and transmits the generated first VR information to the set-top box 120 in a separate transmission channel different from the video bit stream.

In this case, the first VR information to be transmitted may be divided into a predetermined size and transmitted in segment units. When the storage such as a hard disk exists in the set-top box 120, the entire first VR information may be transmitted at once.

For reference, in the configuration illustrated in FIG. 1, the video encoder 111 and the VR information extractor 112 are illustrated as being included in the media server 110. However, the video encoder 111 and the VR information extractor are different from each other. 112 may exist and operate separately from the media server 110.

The set top box 120 may include a video decoder 121, a VR information extractor 122, a VR difference calculator 123, and a VR difference image transmitter 124.

Here, the video decoder 121 decodes (decodes) the video bit stream transmitted from the media server 110 to generate a reproduced image.

In addition, the VR information extraction unit 122 extracts VR information (hereinafter referred to as second VR information) from the playback image generated by the video decoder 121.

For reference, the VR information extracting unit 122 may include a PTS (Presentation Time Stamp) value, which is time information, and a program ID, which is an identifier for identifying content, in the second VR information.

In addition, the VR difference calculator 123 calculates and calculates a VR difference using a difference between the first VR information transmitted from the media server 110 and the second VR information generated by the VR information extractor 122. A VR difference image (hereinafter, referred to as a VR_Diff image) is generated based on the VR difference.

In this case, the VR difference calculator 123 synchronizes the first VR information and the second VR information based on the PTS value and the program ID to generate the VR_Diff image.

Here, the VR_Diff image is information related to the image quality viewed by the viewer, and can be easily generated by calculating the difference between the first VR information and the second VR information, and the amount of computation required is very small. Therefore, the computational burden for calculating the VR_Diff image in the set-top box 120 is also very small.

In addition, the VR_Diff image has a difference value only in the section deteriorated by packet loss, and has a value of '0' in the remaining section without deterioration, so the amount of data is not large. In the case of using the compression, the amount of data can be further reduced.

A detailed description of the compression method of the VR information (VR_Diff image) will be described later with reference to FIGS. 10 to 15.

In addition, the VR difference image transmitter 124, that is, the VR_Diff image transmitter 124 compresses the VR_Diff image generated by the VR difference calculator 123 and transmits the compressed image to the quality management server 130.

In this case, the VR_Diff image may be transmitted by using a reliable channel such as TCP or may be redundantly transmitted several times to prevent data loss during transmission.

Meanwhile, the quality management server 130 receives the VR_Diff image from the set-top box 120 and measures the image quality degradation of the image reproduced in the set-top box 120 using the VR_Diff image.

In this case, the measurement of image quality deterioration uses an estimate of a distortion amount for packet loss generated during transmission of data from the media server 120 to the set-top box 120 in terms of PSNR, and improves the existing PSNR. It uses a new quality measure called Networked PSNR (NPSNR).

은 VR 정보로 이를 추정한 값이다.The NPSNR represents the quality of the image reproduced in the set-top box 120 based on the encoded image, not the original image, and is a value for the 2D image.

Is the value estimated by VR information.

과, 열화 횟수, 임계 열화 횟수, 임계 열화율, 평균 임계 열화량 및 평균 열화량과 같은 열화 척도들을 이용하여 셋탑박스(120)에서 재생되는 영상에 대한 화질 열화를 측정한다.Quality management server 130 described above

And deterioration quality of the image reproduced by the set-top box 120 by using deterioration measures such as deterioration times, threshold deterioration times, critical deterioration rates, average critical deterioration amounts, and average deterioration amounts.

A detailed description of the image quality degradation degree measurement of the quality management server 130 will be described later.

Hereinafter, a configuration of a system for monitoring video quality of an IPTV according to another embodiment of the present invention will be described with reference to FIG. 2.

FIG. 2 is a diagram illustrating a configuration of a system for monitoring video quality of an IPTV in an offline manner, and includes a media server 210, a set-top box 220, and a quality management server 230.

First, the media server 210 has the same configuration as the media server 110 shown in FIG. 1, and if different, the media server 210 shown in FIG. 2 sets the generated first VR information into a set-top box ( It is transmitted to the quality control server 130, not 120.

The set top box 220 may include a video decoder 221, a VR information extractor 222, and a VR information transmitter 223. Among them, the video decoder 221 and the VR information extractor 222 have the same functions as the video decoder 121 and the VR information extractor 122 of the set-top box 120 shown in FIG. The transmitter 223 compresses the second VR information extracted by the VR information extractor 222 and transmits the second VR information to the quality control server 230.

That is, in the online method, the set-top box 120 compresses the VR_Diff image and transmits it to the quality management server 130. In the offline method, the set-top box 220 compresses the second VR information and transmits the second VR information to the quality management server 230. There is a difference.

Therefore, the offline method does not need to generate the VR_Diff image in the set-top box 220, which reduces the consumption of computational resources of the set-top box 230, so that the image quality can be monitored even in a set-top box having a lower specification than the online method. There are advantages to it.

Meanwhile, the quality control server 230 receives the first VR information transmitted from the media server 210 and the second VR information transmitted from the set top box 220. Thereafter, the quality control server 230 synchronizes the first VR information and the second VR information based on the PTS value and the program ID included in the first VR information and the second VR information, and uses the difference of each VR information. Create a VR_Diff image.

Since the quality management server 230 uses the VR_Diff image to measure image quality deterioration of the image reproduced in the set-top box 220, the quality management server 130 shown in FIG. 1 will be omitted.

For reference, the offline quality management server 230 does not need to store both the first VR information and the second VR information.

That is, since the offline quality management server 230 generates the VR_Diff image using the first VR information and the second VR information, when the first VR information and the VR_Diff image exist, the second VR information is used. On the contrary, when the second VR information and the VR_Diff image exist, the first VR information may be restored using the second VR information and the VR_Diff image.

Therefore, there is no need to store both the first VR information and the second VR information, and there is an advantage that can contribute to securing the storage space.

Hereinafter, the VR information of the present invention will be described in detail with reference to FIG. 3.

3 is a diagram for VR information according to an embodiment of the present invention.

VR information according to an embodiment of the present invention, as shown in Figure 3, in the two-dimensional video frame to sample the pixels located in the vertical, diagonal, horizontal direction, etc. to configure the one-dimensional information, and then to the time axis Information about projection of 3D video information to 2D information by sampling pixels at the same position for successive video frames.

Although the spatial information included in the VR information is only a small part of the original image, it was confirmed through experiments that the information amount reflects a large part of the 2D frame information. In other words, the experiment confirmed that the PSNR value of the two-dimensional frame between the original video and the set-top box playback image is highly correlated with the PSNR value calculated only with their VR information. Can be estimated.

The theoretical background of the present invention is as follows.

를 원본 영상의 픽셀값,

는 셋탑박스 재생 영상의 픽셀값 ,

는 인코딩 후 재생 영상 프레임 내의 픽셀값을 나타내는 확률변수라 하자. 셋탑박스에서 재생되는 영상의 총 왜곡량

을 아래의 <수학식 1>과 같이 정의하도록 한다. 여기서 E[X]는 확률변수 X의 기대값(즉, 평균)이다.

Is the pixel value of the original image,

Is the pixel value,

Is a random variable that represents a pixel value in a playback video frame after encoding. Total distortion of video played back on set-top box

To be defined as in Equation 1 below. Where E [X] is the expected value (ie mean) of the random variable X.

이며, n 번째 프레임의 i, j 번째 픽셀값을 나타낸다.here

, I, j th pixel value of the n th frame.

는 인코딩 과정에서 발생한 왜곡량이며,

는 전송 과정 중 발생된 패킷 손실에 의해 야기된 왜곡량이다. 두 왜곡량이 서로 독립적이라 가정하면

은 두 왜곡량의 합과 같다. 그런데

는 인코딩 과정에서 알 수 있는 양이지만,

는 알 수 없는 양이고 또한, 셋탑박스에서는 원본 영상이 가용되지도 않으므로

은 셋탑박스에서 알 수 없는 양이다. double

Is the amount of distortion that occurs during encoding.

Is the amount of distortion caused by packet loss generated during the transmission process. Suppose the two distortion amounts are independent of each other

Is equal to the sum of the two distortion amounts. By the way

Is the amount known during encoding,

Is an unknown amount and the original video is not available in the set-top box.

Is an unknown amount in the set-top box.

를 추정하여 화질 열화의 척도를 제안하는 것을 하나의 목적으로 하며, 정확한

양을 알기 위해서는 인코딩된 영상의

가 필요하나, 셋탑박스에서 무결한 인코딩된 영상을 기대할 수 없기 때문에 이 양을 추정하기 위해 상술한 VR 정보를 이용한다.In the present invention

Is to propose a measure of image quality deterioration by estimating

In order to know the quantity,

Is required, but since the encoded video cannot be expected in the set-top box, the above-mentioned VR information is used to estimate the amount.

, 셋 탑박스에서 재생된 영상에 대한 VR 정보를

라 하면

의 추정치

은 아래의 <수학식 2>와 같이 근사화할 수 있다.VR information about the image of the bit stream obtained in the encoding step

Information about the video played back on the set-top box.

If

Estimate of

Can be approximated as in Equation 2 below.

이다.here

to be.

와, 셋탑박스에서 재생되는 영상에 대한 VR 정보인

를 가지고

을 추정한다.That is, VR information about the encoded image

VR information about the video played on the set-top box

Have

Estimate

If there is no degradation due to an error generated during the transmission process, the total distortion amount is equal to the distortion amount generated during the encoding process, and whether the image quality degradation is caused by a transmission error from Equation 2 and the amount of degradation You can get information about how much it is.

을 이용하여 Back-end 단에서 발생한 화질 열화양의 척도를 정의하도록 하며, 또한, 보다 직관적인 통찰력을 제공하기 위하여

을 PSNR로 환산한 값을 사용하여 셋탑 박스에서 재생되는 영상의 화질을 평가하도록 한다.For reference, the amount of distortion generated during the encoding process is not an interest of the present invention.

In order to define the measure of image quality deterioration occurred in the back-end stage, and to provide more intuitive insight

The PSNR value is used to evaluate the image quality of the image played in the set-top box.

은 VR 정보를 이용하여 NPSNR를 추정한 값이다.To this end, a measure of quality for measuring image quality degradation proposed by the present invention is NPSNR (Networked PSNR) defined by Equation 3 below. Here, NPSNR represents the quality of the image reproduced in the set-top box based on the encoded image, not the original image, and is a value for the 2D image, which is defined by Equation 4.

Is an estimated value of NPSNR using VR information.

Here, c = 0.65025, which is a constant normalized so that NPSNR is 50dB when there is no packet loss.

와

정보를 단순 비교하기만 해도 전송 과정 중에 발생한 에러(열화)의 위치와 에러(열화)가 지속된 시간, 에러(열화)의 발생 횟수 등에 대한 정보를 얻을 수 있으며,

을 통해 얼마나 심하게 화질(화면)이 열화되었는지를 추정할 수 있다.As can be seen from the above equation,

Wow

By simply comparing the information, it is possible to obtain information about the location of the error (deterioration), the duration of the error (deterioration), the number of occurrences of the error (deterioration), etc.

It is possible to estimate how badly the picture quality is degraded.

Hereinafter, a method of measuring (evaluating) image quality degradation in the quality control servers 130 and 230 will be described in detail.

In order to measure image quality deterioration in the quality control server 130 or 230 according to an exemplary embodiment of the present invention, first, the following amounts are defined.

Degradation time

는 k번째 열화가 시작된 프레임 시간이며,

는 k번째 열화가 종료된 시간을 나타낸다. 따라서, <수학식 5>

를 통해 k번째 열화가 지속된 시간을 알 수 있다.here

Is the frame time at which the kth degradation started,

Denotes the time at which the k-th degradation has ended. Therefore, <Equation 5>

This shows how long the kth degradation lasted.

이 최대치(즉 50dB)가 아닌 시점을 찾으면 된다.For reference, the beginning and end of deterioration

You can find a time point other than this maximum (ie 50dB).

* Critical degradation time:

이하의 화질을 갖는 구간을 의미한다.The threshold deterioration interval is critical for any one of the frames of the deterioration interval described above.

It means a section having the following image quality.

은 시청자의 눈에 불편을 줄 수 있는 화질 열화를 가져오는

양으로서, 눈에 불편을 줄 수 있는 화질 열화는

이 사전에 설정된 임계값보다 작으면 발생하는 것으로 간주한다.Critical

Is an image quality degradation that can be inconvenient to viewers.

As a quantity, the image quality deterioration that may cause inconvenience to eyes

It is considered to occur if it is less than this preset threshold.

4 is a diagram illustrating a degradation section and a critical degradation section according to an embodiment of the present invention.

The first and third deterioration sections were included as critical deterioration sections because they were smaller than the threshold value, but the second deterioration sections were not included as critical deterioration sections because the deterioration amount was small.

In order to quantify the degradation of the image quality reproduced in the set-top box using the above-described deterioration period and the critical deterioration period, the present invention proposes the following deterioration measures.

1.degradation count:

Kd: the largest k of

2. Critical degradation count:

Kcd: the largest k of

3. Critical degradation ratio:

4. Average threshold degradation NPSNR:

5. Average degradation

here,

6. Playback quality scale:

, for the nth frame.

, for the nth frame.

Referring to each of the deterioration measures described above, first, the number of degradations refers to the number of times that degradation occurs in the entire video sequence time, that is, the number of degradation intervals, and the number of threshold degradations refers to the number of critical degradation intervals.

값으로 정의될 수 있다.In addition, the critical degradation rate refers to the ratio of time occupied by all critical degradation intervals in the total time, and the average threshold degradation amount is an average of the frames constituting all the critical degradation intervals.

Can be defined as a value.

In addition, the average degradation amount is obtained by converting an average distortion amount between two VR information into an NPSNR value, and a reproduction quality measure is defined as an NPSNR value in units of frames.

이 떨어지더라도 눈에 잘 띄지 않을 수 있다. 영상의 종류에 따라 다르긴 하나, 실험적으로, 보통

이 45dB 이하 정도가 되면 눈에 불편을 줄 수 있는 열화가 검출되는 경향이 있다.For reference, when performing the error suppression function in the set-top box, small degradation

Even if it falls, it may not be noticeable. It depends on the type of image, but experimentally, usually

If it is less than 45dB, the deterioration which may cause an inconvenience to an eye tends to be detected.

값의 설정 예로서 45dB을 사용하도록 한다. 그러나, 당업자의 실시예에 따라 임계

값은 다른 값으로 설정될 수도 있다.Critical in the present invention

Use 45dB as an example of setting the value. However, according to embodiments of those skilled in the art

The value may be set to another value.

Hereinafter, the configuration of the quality control server (130, 230) of the present invention with reference to FIG.

5 is a block diagram showing the configuration of a quality control server according to an embodiment of the present invention.

The quality control server 500 according to an embodiment of the present invention includes a receiver 510, an image quality estimation value calculator 520, an image quality deterioration scale calculator 530, a sensory image quality calculator 540, and a storage 550. And a graphic user interface providing unit 560.

For reference, the components 510 to 560 of the quality management server illustrated in FIG. 5 are for both an online method and an offline method, and in the case of the offline method, a VR_Diff generation for generating a VR_Diff image in addition to the component shown in FIG. 5. It may further include a portion (not shown).

When the quality management server 500 is an online method, the receiving unit 510 of the quality management server 500 receives the VR_Diff image from the set top box, and in the offline method, the first VR information and the first VR information are received from the media server and the set top box. 2 VR information is received to generate a VR_Diff image.

Thereafter, the quality management server 500 measures the degradation of the playback quality of one video content by using the VR_Diff image.

)을 계산하고, 화질 열화 척도 계산부(530)는 본 발명에서 제안하는 화질 열화 척도인 열화 횟수, 임계 열화 횟수, 임계 열화율, 평균 열화량 및 평균 임계 열화량 등을 계산한다.At this time, the image quality estimation value calculation unit 520 may estimate the image quality for each frame (

), And the image quality deterioration scale calculation unit 530 calculates the number of deterioration, the number of critical deterioration, the critical deterioration rate, the average deterioration amount, and the average critical deterioration amount, which are the image deterioration measures proposed by the present invention.

Here, the number of degradations is the number of times that degradation occurs in the entire video sequence time, that is, the number of degradation intervals, and the number of threshold degradations means the number of critical degradation intervals.

In addition, the critical deterioration rate is a ratio of time occupied by all critical deterioration intervals in the total time, and the average deterioration amount is converted into an NPSNR value by an average distortion amount between two VR information.

값이다.Also, the average threshold degradation amount is an average of the frames constituting all the threshold degradation intervals.

Value.

For reference, in the present invention, the quality deterioration scale calculation unit 530 calculates each quality deterioration scale, but there are separate components corresponding to each quality deterioration scale, so that the corresponding quality deterioration scale may be calculated (eg. For example, the number of deterioration is calculated by the deterioration count calculation unit).

Meanwhile, although the sensory image quality calculator 540 does not present a detailed algorithm in the present invention, it may calculate subjective image quality using human visual characteristics from VR information.

Meanwhile, the storage 550 stores a value for evaluating image quality deterioration calculated by the above-described units 520 and 530. In addition, the storage 550 stores the VR_Diff image received from the set-top box in the online manner, and the VR_Diff generated by receiving the first VR information and the second VR information from the media server and the set-top box in the offline manner. Save the image.

Meanwhile, the graphic user interface providing unit 560 provides various information through a graphic user interface (hereinafter referred to as a GUI) so that the quality management operator can view the quality information when necessary.

The information provided by the GUI providing unit 560 includes NPSNR graphs and various image quality deterioration scale values, VR information (first VR information) of encoded images, VR information (second VR information) of images played in the set-top box, and VR. VR_Diff image between the information.

FIG. 6 is a diagram illustrating viewing quality information of content watched by a specific subscriber provided by a quality management server according to an exemplary embodiment of the present invention.

The image quality deterioration data is recorded in the storage 550 in the form of a structure having a data structure as shown in FIG.

When the viewing quality information shown in FIG. 6 is recorded in the storage 550, the quality management operator can access this information at any time and view the quality information on the content viewed by the subscriber in the form of a text or a graph.

Hereinafter, a method of representing and synchronizing VR information will be described with reference to FIGS. 7 to 9, and the first VR information and the first method are used to generate the VR_Diff image in the offline quality management server 230 illustrated in FIG. 2. 2 Assume that the VR information is synchronized.

For reference, the reason for synchronizing the first VR information and the second VR information to generate the VR_Diff image will be described briefly. In the offline method, the media server 210 and the set-top box 220 respectively generate the VR information (the first). VR information and second VR information) is transmitted to the quality management server 230, and in this case, it is highly likely that the first VR information and the second VR information do not exactly match 1: 1 for various reasons.

Since VR information is transmitted to the quality management server 230 through a reliable and secure channel, VR information itself is rarely lost, but the playback image of the set-top box 220 is missing frames due to transmission errors or other reasons. If the same frame is repeated, the VR information may be missing or repeated.

Therefore, in order to evaluate the deterioration of image quality of the playback image of the set-top box 220 (that is, to generate a VR_Diff image), it is necessary to synchronize the first VR information and the second VR information. A program ID may be added, which is an identifier that uniquely identifies time information and content.

7 is a diagram illustrating a method of expressing VR information for VR synchronization according to an embodiment of the present invention.

Using the video presentation time stamp (PTS) value used in the MPEG-2 System as the time information to the VR value extracted from the frame, "time information + VR value" is used as one VR information presentation unit.

Since the video PTS value is time information indicating when the video frame is played, the media server 210 and the set-top box 220 have the same value for a specific frame. The 210 and the set-top box 220 may uniquely identify the specific frame.

8 is a diagram illustrating a form of VR information for VR synchronization according to an embodiment of the present invention.

In the form of VR information for VR synchronization, a VR chunk (an identifier) is added to the VR information presentation unit during the unit time shown in FIG. 7 by adding a program ID (identifier) that is an identifier for uniquely identifying the content. chunk).

The VR information for one content may have a form in which VR chunks are continuously connected as shown in FIG. 8.

9 illustrates a method of synchronizing VR information according to an embodiment of the present invention.

As described above, since the first VR information of the media server 210 and the second VR information of the set-top box 220 are not information available at exactly the same time, a delay may occur between the two information.

In order to compare the delayed VR information, a method of synchronizing the two informations is required, and the offline quality management server 230 uses the video PTS information of the MPEG-2 PES packet included in the VR information for synchronization between the VR information. .

If there is a missing frame in the set-top box 220, the PTS value and the VR information of the previous frame may be replaced or the quality deterioration measure may be calculated by ignoring the missing frame.

As illustrated in FIG. 9, the quality management server 230 may easily synchronize the two information by comparing the VR information having the same PTS value in VR information units.

In the above, the method of expressing and synchronizing the VR information in the offline quality control server 230 has been described with reference to FIGS. 7 to 9, but the set-top box 120 of the online method expresses and synchronizes the VR information in the same manner. can do.

Hereinafter, the storage method of the VR information will be briefly described.

The VR information generated in the set-top box is information to be preserved for evaluating image quality deterioration. The place for storing the VR information may be a quality control server, or in some cases, may be a storage such as a hard disk in the set-top box.

If the amount of storage that the QC server can handle is burdensome, all VR information for one audience is stored on the hard disk in the set-top box, and the QC server can access and use the hard disk in the set-top box when necessary. It may be.

If the VR information is stored in the quality control server, in order to minimize the storage capacity, the VR information may be converted into a lossless compressed VR_Diff image instead of the generated VR information, and the VR information of the media server may be stored in the media server. Since it can be provided when needed from, it is possible to recover the VR information of the set-top box using the stored VR_Diff image and the VR information of the media server.

In addition, when VR information is stored in the hard disk of the set-top box, the online set-top box 120 losslessly compresses the VR_Diff image to store the VR_Diff image in the hard disk, and the offline set-top box 220 generates the VR information can be compressed and stored on the hard disk.

Then, at the request of the quality management server, the set-top box 220 transmits the VR information or the VR_Diff image compressed and stored in the hard disk to the quality management server using a reliable channel.

Hereinafter, a compression method of VR information will be described in detail with reference to FIGS. 10 to 15.

FIG. 10 is a diagram illustrating VR information extracted from an hour-long video content according to an embodiment of the present invention.

The amount of data of VR information extracted from an SD video content having an 720x480 resolution of one hour is 480 B / frame x 30 frames / sec x 3600 sec / hour = 51,840,000 B / hr = 115,200 kbps.

That is, the transmission bandwidth required for transmitting the VR information of this content to the quality management server is 115.2kbps, and 51.84MB of storage space is required to store this VR information.

One hour of viewing quality information for one viewer is a very large amount of data. Therefore, there is a need for a method of reducing VR information. Hereinafter, various methods for reducing the amount of transmission data by reducing VR information will be described.

11 is a diagram illustrating a reduction method by spatial subsampling according to an embodiment of the present invention.

When extracting the VR information from the content, as shown in FIG. 8, the VR information may be reduced by subsampling from about 2: 1 to about 8: 1 in the spatial direction (vertical direction). If subsampling is performed at 8: 1, it is experimentally confirmed that the estimation performance of estimating the NPSNR is not significantly different.

This means that only enough samples to be statistically significant have little effect on the estimated performance. This reduces the original VR data amount of 51.84MB to 6.48MB, which can be transmitted with a transmission bandwidth of 14.4kbps.

12 is a diagram illustrating a reduction method by temporal subsampling according to an embodiment of the present invention.

If additionally subsampling VR information reduced by spatial subsampling shown in FIG. 11 from 2: 1 to 3: 1 temporally, the data amount can be further reduced, and the effect thereof is as shown in FIG. 8. .

If temporal subsampling is additionally applied to the VR information reduced by spatial subsampling, the VR information can be reduced to about 2.16MB and 4.8kbps.

13 is a view illustrating a reduction method by lossless compression according to an embodiment of the present invention.

Information sub-sampled temporally, spatially or spatiotemporally by the reduction method as shown in FIGS. 11 and 12 may further reduce the data amount by the lossless compression method as shown in FIG. 13.

Applying a lossless compression method can further reduce the amount of data to about 1/2 to 1/3, and in the case of the VR information shown in FIG. 9, can further reduce the amount of data up to about 1 MB and 2 kbps. have.

This is a small amount of data that can not be compared with the existing method (J.240, YAMADA) which requires a data amount of several hundred kbps to several Mbps as the data amount of feature information.

14 is a diagram illustrating a method of reducing information by extracting VR information by RTP packet loss detection according to an embodiment of the present invention.

The method shown in FIG. 14 does not extract the VR information for every frame, but uses the packet loss information provided by the RTP packet layer, and when the loss is detected, the VR for the image played in the set-top box for a predetermined time therefrom. By extracting the information and not extracting the VR information in the remaining time intervals, the data amount of the VR information can be reduced.

It takes a certain amount of time (hundreds of ms to several seconds) before the lost packet affects the viewer's TV screen. Therefore, when a packet loss event occurs in the packet layer, VR information is only displayed for a certain period of time (N seconds). Extract.

If no packet loss occurs, the VR information is not extracted. Therefore, the VR information is extracted in proportion to the amount of packet loss. If no packet loss occurs, the amount of data of the VR information is almost zero. .

FIG. 15 illustrates a method of reducing information by extracting VR information by video bitstream error detection according to an embodiment of the present invention.

The method illustrated in FIG. 15 is a method of reducing the data amount of VR information by starting to extract VR information from the moment when the video decoder of the set-top box detects an error of a bit stream syntax structure.

Since the video bitstream is independently encoded in GoP (group of picture) units, even if an error occurs in any frame, the error does not affect the next GoP.

That is, since the error only affects the remaining frames in the same GoP, it is sufficient to extract VR information only during that GoP period.

In general, in broadcast applications, since GoP size is 0.5 seconds, that is, 15 frames, when the error of the bit stream syntax structure is detected once, the VR information is extracted only up to 15 frames, which can drastically reduce the amount of data of the VR information. have.

Hereinafter, the operation of each component of the system for monitoring the video quality of the IPTV in an online manner will be described with reference to FIGS. 16 to 18.

16 is a flowchart illustrating the operation of the media server 110 in an online manner according to an embodiment of the present invention.

The media server 110 compresses the video signal and stores the compressed video stream (S1601).

After step S1601, the media server 110 extracts first VR information from the compressed video stream, that is, the encoded image (S1602).

After step S1602, the media server 110 includes the PTS (Presentation Time Stamp) value, which is time information, and the program ID, which identifies the content, in the extracted first VR information (S1603).

After step S1603, the media server 110 stores the VR information, and when the viewer requests it later, transmits the stored 1 VR information to the set-top box 120 (S1604).

In this case, the first VR information to be transmitted may be divided into a predetermined size and transmitted in segment units. When the storage such as a hard disk exists in the set-top box 120, the entire first VR information may be transmitted at once.

17 is a flowchart illustrating the operation of the set-top box 120 in an online manner according to an embodiment of the present invention.

The set top box 120 receives the video bit stream and the first VR information from the media server 110 (S1701).

For reference, in step S1701, for convenience of description, the reception of the video bit stream and the first VR information is described as one step. However, the first VR information is set as a separate transmission channel different from the video bit stream. ) May be sent.

In addition, the set-top box 120 may receive the first VR information in segments divided into a predetermined size, or when the storage such as a hard disk is present in the set-top box 120, the entire first VR information may be received at once. It may be.

After step S1701, the set-top box 120 decodes the video bit stream to generate a playback image (S1702).

After step S1703, the set top box 120 extracts second VR information from the decoded playback image (S1703).

After step S1703, the set-top box 120 includes a presentation time stamp (PTS) value, which is time information, and a program ID, which is an identifier for identifying content, in the second VR information (S1704).

After the step S1704, the set-top box 120 synchronizes the first VR information and the second VR information, and generates a VR_Diff image (S1705).

At this time, the set-top box 120 synchronizes the first VR information and the second VR information based on the PTS value and the program ID included in each VR information.

After step S1705, the set-top box 120 compresses and stores the VR_Diff image and transmits it to the quality management server (S1706).

18 is a flowchart illustrating the operation of the quality control server 130 in an online manner according to an embodiment of the present invention.

The quality management server 130 receives and stores the VR_Diff image from the set-top box 120 (S1801).

After step S1801, the quality management server 130 calculates an NPSNR estimate value using the VR_Diff image (S1802).

After step S1802, the quality management server 130 calculates a quality deterioration measure value (S1803).

In this case, the image quality deterioration measure for measuring the image quality deterioration is a deterioration number, a threshold deterioration number, a threshold deterioration rate, an average deterioration amount, and an average threshold deterioration amount.

After step S1803, the quality management server 130 stores the quality deterioration measurement value in the storage, and provides various information using the same to the quality management operator later (S1804).

Hereinafter, the operation of each component of the system for monitoring the video quality of the IPTV in an offline manner will be described with reference to FIGS. 19 to 22.

19 is a flowchart illustrating an operation of the media server 210 in an offline manner according to an embodiment of the present invention.

The media server 210 compresses the video signal and stores the compressed video stream (S1901).

After step S1901, the media server 210 extracts first VR information from the compressed video stream, that is, the encoded image (S1902).

After step S1902, the media server 210 includes a PTS (Presentation Time Stamp) value, which is time information, and a program ID, which is an identifier for identifying content, in the extracted first VR information (S1903).

After step S1903, the media server 210 stores the first VR information, and transmits the stored first VR information to the quality management server 230 at the request of the quality management server 230 (S1904).

20 is a flowchart illustrating the operation of the set-top box 220 in the offline manner according to an embodiment of the present invention.

The set top box 220 receives the video bit stream from the media server 210 (S2001).

After step S2001, the set-top box 220 decodes the video bit stream to generate a playback image (S2002).

After step S2003, the set-top box 220 extracts the second VR information from the decoded playback image (S2003).

After step S2003, the set-top box 220 includes a PTS (Presentation Time Stamp) value, which is time information, and a program ID, which is an identifier for identifying content, in the second VR information (S2004).

After step S2004, the set-top box 220 compresses and stores the second VR information and transmits it to the quality management server (S2005).

For reference, in the offline method, the set-top box 220 does not need to generate a VR_Diff image, which reduces the consumption of computational resources of the set-top box 220, so that the set-top box 220 can operate even in a lower-level set-top box. There is this.

21 is a flowchart illustrating the operation of the quality control server 230 in an online manner according to an embodiment of the present invention.

The quality management server 230 receives the first VR information transmitted from the media server 210 and the second VR information transmitted from the set top box 220 (S2101).

After step S2101, the quality management server 230 synchronizes the two VR information based on the PTS value and the program ID included in the first VR information and the second VR information (S2102).

After step S2102, the quality management server 230 generates a VR_Diff image by using the difference of each VR information (S2103).

After step S2103, the quality management server 230 calculates an NPSNR estimate using the VR_Diff image (S2104).

After step S2104, the quality management server 230 calculates a quality deterioration measure value (S2105).

In this case, the image quality deterioration measure for measuring the image quality deterioration is a deterioration number, a threshold deterioration number, a threshold deterioration rate, an average deterioration amount, and an average threshold deterioration amount.

After step S2105, the quality management server 230 stores the quality deterioration measurement value in the storage, and provides various information using the quality management operator later (S2106).

Hereinafter, the simulation results performed to verify the validity and performance of the image quality degradation measurement method proposed in the present invention will be described.

The video used in the experiment is an H.264 stream provided by the real IPTV business. The characteristics are as shown in Table 1. VR information is generated by extracting the pixels on the vertical line at the center of the frame.

는 H.264 스트림을 오류없이 디코딩한 재생 영상으로부터 추출하였으며, 이후 H.264 스트림을 1,500 바이트 크기의 패킷으로 나누고 패킷 손실율 0.1%로 무작위로 패킷을 손실시킨 후, 디코더에서 재생된 영상으로부터 추출한 VR 정보를 셋탑박스에서 재생된 영상의 VR 정보

라 가정하였다.In addition, VR information of the encoded playback image

Extracted H.264 stream from error-free decoded playback video, and then divided the H.264 stream into packets of 1,500 byte size, randomly losing packets with a packet loss rate of 0.1%, and then extracting VR from the video played back from the decoder. VR information of video played on set-top box

Assume that

<Table 1> Experimental Video

을 사용하여 얼마나 잘 추정하였는가’가 관심사항 이다. The verification of the performance is based on the VR information obtained from the deterioration scale calculated by NPSNR obtained for 2D image.

How well did you estimate using ??

The result of estimating the NPSNR by the technique of the present invention for the experimental image is shown in FIG.

22A to 22C illustrate NPSNR estimation performances of experimental images of Table 1 according to an embodiment of the present invention.

이 NPSNR 을 잘 근사화 해냄을 볼 수 있다.In FIG. 22A to FIG. 22C, a section showing an NPSNR value smaller than 50 dB is a section in which degradation occurs due to packet loss. You can see that the VR information detects the deterioration point as well as the 2D video frame.

It can be seen that the NPSNR is well approximated.

의 유용성은 경미한 화질 열화보다는 심각한 화질 열화를 검출해 내고, 이 때의 열화량을 근사화하는 데 있다고 볼 수 있다. 경미한 화질 열화는 시청자들의 눈에 잘 보이지 않기 때문이다.As a quantitative measure of quality

The usefulness of can be seen in detecting serious image quality deterioration and approximating the amount of degradation at this time, rather than a slight image quality deterioration. The slight deterioration in image quality is difficult to see in the viewers' eyes.

을 근거로 하여 화질 열화 척도를 계산하면 <표 2>와 같다.

Based on the calculation, the quality deterioration scale is calculated as shown in Table 2.

For reference, in Table 2, '2D' is a value calculated for 2D playback video, and 'VR' is an estimated value based on VR information only.

<Table 2> Estimation Performance of Image Quality Degradation Scale

On all scales, we can see that the value estimated by VR information is very close to the value calculated for 2D image. From these values, there were 32 deteriorations in the case of 'winter bird' image, but there were 28 deterioration among them. can do.

For reference, the deterioration shown in <Table 2> is set for the simulation to evaluate the performance of the proposed method, and in practice, commercial service is impossible. IPTV operators can use this information to provide on-site data for network or service improvement.

23A to 23D illustrate VR_Diff images for an experimental image of Table 2 according to an embodiment of the present invention.

23A to 23D, it is easy to see visually how much deterioration has occurred at which position of the entire frame.

The foregoing description of the present invention is intended for illustration, and it will be understood by those skilled in the art that the present invention may be easily modified in other specific forms without changing the technical spirit or essential features of the present invention. will be.

It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined form.

The scope of the present invention is shown by the following claims rather than the above description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention. do.

1 is a diagram illustrating a configuration of a system for monitoring video quality of an IPTV according to an embodiment of the present invention.

2 is a diagram illustrating a configuration of a system for monitoring video quality of an IPTV according to another embodiment of the present invention.

3 is a diagram for VR information according to an embodiment of the present invention.

4 is a diagram illustrating a degradation section and a critical degradation section according to an embodiment of the present invention.

5 is a block diagram showing the configuration of a quality control server according to an embodiment of the present invention.

FIG. 6 is a diagram illustrating viewing quality information of content watched by a specific subscriber provided by a quality management server according to an exemplary embodiment of the present invention.

7 is a diagram illustrating a method of expressing VR information for VR synchronization according to an embodiment of the present invention.

8 is a diagram illustrating a form of VR information for VR synchronization according to an embodiment of the present invention.

9 illustrates a method of synchronizing VR information according to an embodiment of the present invention.

FIG. 10 is a diagram illustrating VR information extracted from an hour-long video content according to an embodiment of the present invention.

11 is a diagram illustrating a reduction method by spatial subsampling according to an embodiment of the present invention.

12 is a diagram illustrating a reduction method by temporal subsampling according to an embodiment of the present invention.

13 is a view illustrating a reduction method by lossless compression according to an embodiment of the present invention.

14 is a diagram illustrating a method of reducing information by extracting VR information by RTP packet loss detection according to an embodiment of the present invention.

FIG. 15 illustrates a method of reducing information by extracting VR information by video bitstream error detection according to an embodiment of the present invention.

16 is a flowchart illustrating an operation of a media server in an online manner according to an embodiment of the present invention.

17 is a flowchart illustrating the operation of the set-top box in the online manner according to an embodiment of the present invention.

18 is a flowchart illustrating an operation of a quality control server in an online manner according to an embodiment of the present invention.

19 is a flowchart illustrating an operation of a media server in an offline manner according to an embodiment of the present invention.

20 is a flowchart illustrating the operation of the set-top box in an offline manner according to an embodiment of the present invention.

21 is a flowchart illustrating an operation of a quality control server in an online manner according to an embodiment of the present invention.

22A to 22C illustrate NPSNR estimation performances of experimental images of Table 1 according to an embodiment of the present invention.

23A to 23D illustrate VR_Diff images of an experimental image of Table 2 according to an embodiment of the present invention.

<Description of the code | symbol about the principal part of drawing>

510: receiver

520: image quality estimation value calculation unit

530: image quality deterioration scale calculation unit

540: sensory image quality calculation unit

550: store

560: Graphical user interface (GUI) provider

Claims (20)

In the method for monitoring the image quality, (a) receiving first visual rhythm information of the encoded image from the first server, (b) extracting second visual rhythm information with respect to the reproduced video obtained by receiving the encoded video over a network; (c) calculating a visual rhythm difference based on the first visual rhythm information and the second visual rhythm information; and (d) transmitting the calculated visual rhythm difference to a second server Including, And the second server measures image quality deterioration of the reproduced image using the visual rhythm difference. The method of claim 1, The first visual rhythm information and the second visual rhythm information are composed of one-dimensional information by partially sampling pixels of a two-dimensional image frame, and sampling three-dimensional images by sampling pixels at the same position for successive image frames on a time axis. The image quality degradation monitoring method of projecting the information to two-dimensional information. The method of claim 2, And wherein the partially sampled pixels are located in at least one of the vertical, diagonal, and horizontal directions of the two-dimensional image frame. The method of claim 1, The second server calculates a reproduction quality estimation value of the reproduced image by using the visual rhythm difference, and at least one of the number of degradations, the number of threshold degradations, a threshold degradation rate, an average threshold degradation amount, and an average degradation amount of the playback image. Image quality degradation monitoring method for calculating a quality degradation measure comprising a. The method of claim 1, The first visual rhythm information and the second visual rhythm information received in step (a) includes a presentation time stamp (PTS) value, which is time information, and a program ID, which is an identifier for identifying content. Way. The method of claim 5, Step (c) is (c-1) synchronizing the first visual rhythm information and the second visual rhythm information based on the PTS value and the program ID; and (c-2) calculating the visual rhythm difference by using the difference between the first visual rhythm information and the second visual rhythm information Image quality degradation monitoring method comprising a. The method of claim 1, The first visual rhythm information and the second visual rhythm information are reduced by temporal subsampling, reduced by spatial subsampling, reduced by lossless compression, extracted by RTP packet loss, and bitstream error. And decompression using at least one of the extraction methods by detection. In the method for monitoring the image quality, (a) receiving from the media server first visual rhythm information about the encoded image, (b) receiving, from the set top box, second visual rhythm information about the decoded playback image, (c) calculating a visual rhythm difference based on the first visual rhythm information and the second visual rhythm information; and (d) measuring image quality deterioration of the reproduced image using the visual rhythm difference Image quality degradation monitoring method comprising a. The method of claim 8, Step (d) (d-1) calculating an image quality estimation value of the playback image Including, wherein the image quality estimation value of the playback image is the image quality degradation monitoring method of expressing the image quality of the playback image based on the encoded image as visual rhythm information. The method of claim 9, Step (d) (d-2) calculating at least one of the number of degradations, the number of threshold degradations, a threshold degradation rate, an average threshold degradation amount, and an average degradation amount of the reproduced video; Image quality degradation monitoring method comprising a. In the device for monitoring the image quality, A receiver for receiving a visual rhythm difference using a difference between first visual rhythm information, which is visual rhythm information on the encoded image, and second visual rhythm information, which is visual rhythm information on the image reproduced in the set-top box, from the set-top box. An image quality estimation value calculator configured to calculate an image quality estimation value of an image reproduced in the set-top box using the visual rhythm difference image; An image quality deterioration scale calculation unit configured to calculate an image quality deterioration measure including at least one of a deterioration number, a deterioration number, a critical deterioration rate, an average critical deterioration amount, and an average deterioration amount of the reproduced image; Graphical user interface for providing image quality monitoring information based on the image quality estimation value and the image quality deterioration measure according to a user's request Image quality degradation monitoring device comprising a. The method of claim 11, wherein The image quality monitoring information includes at least one of a graph of the image quality estimation value, the image quality measurement value, the first visual rhythm information, the second visual rhythm information, and the visual rhythm difference. . The method of claim 11, wherein And the receiving unit receives the first visual rhythm information from a media server according to a monitoring method, and receives the second visual rhythm information from the set top box. The method of claim 13, According to the monitoring method, a visual rhythm difference calculation unit for generating a visual rhythm difference, based on the first visual rhythm information and the second visual rhythm information Further comprising, the image quality degradation monitoring device. The method of claim 14, The visual rhythm difference calculating unit uses the first visual rhythm information by using a presentation time stamp (PTS) value, which is time information included in the first visual rhythm information, and the second visual rhythm information, and a program ID that identifies a content. And synchronize the second visual rhythm information. The method of claim 15, And the visual rhythm difference calculator calculates the visual rhythm difference using the difference between the synchronized first visual rhythm information and the second visual rhythm information. In the set-top box for monitoring the image quality, A video decoder for decoding a encoded image received from a first server through a network to generate a reproduced image; A visual rhythm information extraction unit for extracting second visual rhythm information from the reproduced video; A visual rhythm difference calculator for calculating a visual rhythm difference based on the first visual rhythm information and the second visual rhythm information on the encoded image received from the first server; A visual rhythm difference transmitter for transmitting the visual rhythm difference to a second server that measures image quality deterioration for the reproduced image by using the visual rhythm difference. Including, image quality degradation monitoring device The method of claim 17, The visual rhythm difference calculator is configured to display the first visual rhythm based on a PTS (Presentation Time Stamp) value, which is time information included in the first visual rhythm information, and the second visual rhythm information, and a program ID that identifies a content. Synchronizing information and the second visual rhythm information, and calculating the visual rhythm difference by using a difference between the first visual rhythm information and the second visual rhythm information. The method of claim 17, The second server calculates a reproduction quality estimation value of the reproduced image by using the visual rhythm difference, and at least one of the number of degradations, the number of threshold degradations, a threshold degradation rate, an average threshold degradation amount, and an average degradation amount of the playback image. Image quality deterioration monitoring apparatus for calculating the quality deterioration measure comprising a. The method of claim 17, The first visual rhythm information and the second visual rhythm information are reduced by temporal subsampling, reduced by spatial subsampling, reduced by lossless compression, extracted by RTP packet loss, and bitstream error. The image quality degradation monitoring apparatus, which is compressed using at least one of the extraction method by detection.

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