JP2008017087A - Communication quality estimating method and device, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily estimate reception viewing and listening quality at a local point from quality factor values relating to video/audio signals transmitted between the local point and other points. <P>SOLUTION: A point-to-point quality estimating means 11A estimates point-to-point qualities corresponding to the respective quality factor values obtained in relation to video/audio signals transmitted between the local point and two other points during multipoint communication on the basis of correspondence relation between quality factor values relating to video/audio signals transmitted between the two arbitrary points and point-to-point qualities for the video/audio signals. A reception viewing and listening quality estimating means 11B estimates reception viewing and listening qualities corresponding to point-to-point qualities for the video/audio signals on the basis of correspondence relation between the point-to-point qualities for the video/audio signals and reception viewing and listening qualities for respective video/audio signals reproduced and displayed at the local point, and outputs them as the reception viewing and listening qualities at the local point. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a communication quality estimation technique, and more particularly to a technique for estimating subjective quality when a video / audio signal of multipoint communication is received and viewed at an arbitrary point.

In multi-point communications such as video conferences, differences in network quality such as packet loss and transmission delay time between points, differences in performance of terminals at each point, video / audio encoding method, encoding method, transmission method Depending on quality factors such as differences, the quality of the video / audio signal at each point transmitted to the point may be different.
Conventionally, with regard to such multipoint communication, taking into account the above-mentioned characteristics, subjective evaluation is performed for all combinations of quality factors related to audio and video signals transmitted between each point, and based on these subjective evaluation results. Thus, the reception / viewing quality is obtained when a plurality of video and audio signals transmitted from each point are displayed and reproduced at the point (see, for example, Non-Patent Document 1).

Yamazaki, Morita, Hayashi, Aida, Takeichi, Doi, “Effects of communication quality variations on subjective quality in multipoint video conferencing”, IEICE Technical Report CQ99-57, The Institute of Electronics, Information and Communication Engineers, December 15, 1999 Day

However, in such a conventional technique, it is necessary to subjectively evaluate all combinations of quality factors relating to audio and video signals transmitted between the points, and much labor and time are required to obtain a desired reception / viewing quality. There was a problem. In addition, a subjective quality evaluation test by conversation is performed for multipoint communication connecting three points, and a method for estimating the total quality at the time of communication between three points has been studied, but the number of points has increased from three points. There has been a problem that a technique for easily and accurately estimating the subjective quality of a case has not been realized.
The present invention is for solving such a problem, and can easily estimate the receiving / viewing quality at the local point from the quality factor value regarding the video / audio signal transmitted between the local point and each other point. It is an object to provide a quality estimation method, apparatus, and program.

  In order to achieve such an object, the communication quality estimation method according to the present invention is based on the correspondence relationship for quality estimation stored in advance in the storage unit, and received and reproduced at each point by multipoint communication. A communication quality estimation method used in a communication quality estimation apparatus for estimating reception / viewing quality related to a video / audio signal from another point, and transmitted between two arbitrary points stored in a storage unit by a point-to-point quality estimation unit Obtained for the video and audio signal transmitted between the local point and each other point at the time of the multipoint communication based on the correspondence between the quality factor value related to the video and audio signal and the inter-point quality for the video and audio signal. The point-to-point quality estimation step for estimating the point-to-point quality corresponding to each quality factor value, and transmission / reception between the own point and each other point stored in the storage unit by the reception / viewing quality estimation means Corresponding to the point-to-point quality obtained in the point-to-point quality estimation step based on the correspondence between the point-to-point quality for each video / audio signal and the receiving / viewing quality for each video / audio signal displayed and reproduced at the local point A reception / viewing quality estimation step for estimating and outputting the reception / viewing quality as reception / viewing quality at the local site.

  In addition, another communication quality estimation method according to the present invention is based on the correspondence relationship for quality estimation stored in advance in the storage unit, and the video and audio from each other point received and reproduced at the own point by multipoint communication. A communication quality estimation method used in a communication quality estimation apparatus for estimating reception / viewing quality related to a signal, which relates to a video / audio signal transmitted between two arbitrary points stored in a storage unit by a point-to-point quality estimation unit Based on the correspondence between the quality factor value and the point-to-point quality for the video and audio signal, the quality factor value obtained for the video and audio signal transmitted between the local point and each other point during the multipoint communication is calculated. The point-to-point quality estimation step for estimating the corresponding point-to-point quality and the point-to-point quality estimation means determine the point-to-point quality obtained in the point-to-point quality estimation step. By multiplying based on constant corresponding to the time, and a receiving viewing quality estimation step of estimating a received viewing quality at the own site.

  In addition, another communication quality estimation method according to the present invention is based on the correspondence relationship for quality estimation stored in advance in the storage unit, and the video and audio from each other point received and reproduced at the own point by multipoint communication. A communication quality estimation method used in a communication quality estimation apparatus for estimating reception / viewing quality related to a signal, which relates to a video / audio signal transmitted between two arbitrary points stored in a storage unit by a point-to-point quality estimation unit Based on the correspondence between the quality factor value and the point-to-point quality for the video and audio signal, the quality factor value obtained for the video and audio signal transmitted between the local point and each other point during the multipoint communication is calculated. The point-to-point quality estimation step for estimating the corresponding point-to-point quality and the point-to-point quality estimation means determine the point-to-point quality obtained in the point-to-point quality estimation step. Multiplied based on constant corresponding to the time, by calculating the power roots of the obtained multiplication result, and a receiving viewing quality estimation step of estimating a received viewing quality at the own site.

  Moreover, the communication quality estimation apparatus according to the present invention relates to a video / audio signal from each other point received and reproduced at its own point by multipoint communication based on the correspondence relationship for quality estimation stored in advance in the storage unit. Correspondence between quality factor values related to video / audio signals transmitted between two arbitrary points and the inter-point quality with respect to the video / audio signals, which is a communication quality estimation device for estimating reception / viewing quality A point-to-point quality estimation means for estimating the point-to-point quality corresponding to each quality factor value obtained for the video and audio signal transmitted between the own point and each other point during the multipoint communication based on the relationship; , Inter-point quality for each video / audio signal transmitted between the local point and each other point, and reception / viewing quality for each video / audio signal displayed and reproduced at the local point, stored in the storage unit, Based on the correspondence relationship, and a receiving viewing quality estimation means for estimating output receiving viewing quality corresponding to a point between the quality obtained at a point between the quality estimating means as the received viewing quality at the own site.

  In addition, the program according to the present invention is based on the correspondence relationship for quality estimation stored in advance in the storage unit, and received / viewed quality related to video / audio signals from each other point received and reproduced at the own point by multipoint communication. The quality factor value relating to the video / audio signal transmitted between any two points, which is stored in the storage unit by the point-to-point quality estimation means, and the point-to-point for the video / audio signal Based on the correspondence with quality, the point-to-point quality corresponding to each quality factor value obtained for the video and audio signal transmitted between the local point and each other point during the multipoint communication is estimated. The inter-point quality for each video / audio signal transmitted between the local point and each other point stored in the storage unit by the quality estimation step and the received / viewing quality estimation unit Based on the correspondence with the received and viewed quality for each video and audio signal displayed and reproduced at the local point, the received and viewed quality corresponding to the inter-point quality obtained in the inter-point quality estimation step is set as the received and viewed quality at the local point. A reception / viewing quality estimation step of estimating output is executed.

  According to the present invention, based on the correspondence between the quality factor value related to the video / audio signal transmitted between any two points and the inter-point quality for the video / audio signal, the local point and the two The inter-point quality corresponding to each quality factor value obtained for the video / audio signal transmitted between each other point is estimated, and the inter-point quality for these video / audio signals and each video displayed and reproduced at its own point Based on the correspondence between the audio signal and the received / viewed quality, the received / viewed quality corresponding to the inter-point quality is estimated, and the received / viewed quality corresponding to the inter-point quality is estimated and output as the received / viewed quality at the local point. .

  This eliminates the need for the subject to perform subjective assessments for all combinations of quality factors of audio and video signals transmitted between the points, and makes it easy to obtain the own points and each point. It is possible to easily estimate the reception / viewing quality at the local point from the quality factor value regarding the video / audio signal transmitted between the two.

[First Embodiment]
First, a communication quality estimation apparatus according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing the configuration of the communication quality estimation apparatus according to the first embodiment of the present invention.
This communication quality estimation apparatus 10 is composed of an information processing apparatus having a computer as a whole, and each of the others received and reproduced at its own point by multipoint communication based on the correspondence relationship for quality estimation stored in advance in the storage unit Estimate the receiving / viewing quality of the video / audio signal from the point.

  In the present embodiment, the multipoint is based on the correspondence between the quality factor value related to the video / audio signal transmitted between any two points and the quality between the points for the video / audio signal stored in the storage unit. Estimate the inter-point quality corresponding to each quality factor value obtained for the video and audio signals transmitted between the local point and each other point during inter-communication, and store the local point and each other stored in the storage unit Based on the correspondence between each point quality for each video and audio signal transmitted to and from each point and each receiving and viewing quality for each video and audio signal displayed and reproduced at its own point, the receiving quality corresponding to these point and point quality is received. The viewing quality is estimated and output as the receiving / viewing quality at the local point.

The communication quality estimation apparatus 10 includes an arithmetic processing unit 11 and a storage unit 12.
The arithmetic processing unit 11 has a microprocessor such as a CPU and its peripheral circuits, and reads and executes a predetermined program, thereby realizing various functional means by cooperating the hardware and the program.

The arithmetic processing unit 11 includes an inter-point quality estimating unit 11A and a received / viewing quality estimating unit 11B as the functional units.
The inter-point quality estimation means 11A has a function of estimating the inter-point quality indicating the communication quality of the video / audio signal from the quality factor value regarding the video / audio signal transmitted between the local point and each other point. Yes.
The reception / viewing quality estimation unit 11B estimates the reception / viewing quality when a plurality of video and audio signals transmitted from each point are displayed and reproduced at the own point based on the point-to-point quality obtained by the point-to-point quality estimation unit 11A. It has a function to do.

The storage unit 12 includes a storage device such as a memory or a hard disk, and stores various information and programs used in the arithmetic processing unit 11.
In particular, the storage unit 12 stores, as various information, a correspondence relationship between a quality factor value related to a video / audio signal transmitted between two arbitrary points and a point-to-point quality with respect to the video / audio signal, that is, a quality factor-point-to-point quality relationship. The relationship between the quality between each point for each video / audio signal transmitted between each point and the reception / viewing quality with respect to each video / audio signal displayed and reproduced at its own point, that is, the relationship between the quality between points and reception / viewing quality. Remember.

  In the point-to-point quality estimation unit 11A and the reception / viewing quality estimation unit 11B of the arithmetic processing unit 11, the quality factor-point-to-point quality relationship and the point-to-point quality-receiving / viewing quality that are derived in advance and stored in the storage unit 12. Based on the relationship, the point-to-point quality corresponding to each quality factor value is estimated, and the receiving and viewing quality corresponding to the point-to-point quality is estimated.

The communication quality estimation device 10 has an input / output interface unit for exchanging various types of information with an external device or a storage medium, and an operation / display interface unit for exchanging various types of information with an operator. However, these configurations are the same as those of a general information processing apparatus such as a personal computer, and detailed description thereof is omitted here.
The video / audio signal referred to in the present embodiment is a multimedia signal including both a video signal and an audio signal transmitted between communication terminals.

[Operation of First Embodiment]
Next, the operation of the communication quality estimation apparatus according to the first embodiment of the present invention will be described with reference to FIG. FIG. 2 is a configuration example of multipoint communication.
In the multipoint communication shown in FIG. 2, communication terminals 51 to 53 are arranged at three points 1 to 3, respectively. In the following, a case will be described as an example in which the reception / viewing quality is estimated when the point 1 is the own point and the video and audio signals from the point 2 and the point 3 that are other points are displayed and reproduced at the point.

First, in the arithmetic processing unit 11 of the communication quality estimation apparatus 10, the inter-point quality estimation unit 11 </ b> A determines the video / audio signal transmitted from the point 2 to the point 1 based on the quality factor-inter-point quality relationship in the storage unit 12. The quality Q of the video / audio signal transmitted from the point 2 to the point is estimated by estimating the inter-point quality corresponding to the packet loss rate L _2-1 in the transmission section from the point 2 to the point 1 input as the quality factor value. _2-1 is obtained (point-to-point quality estimation step).

Similarly, the point 3 input as the quality factor value of the video / audio signal transmitted from the point 3 to the point 1 based on the quality factor-point-to-point quality relationship in the storage unit 12 by the point-to-point quality estimation unit 11A. The point-to-point quality corresponding to the packet loss rate L _3-1 in the transmission section from point 1 to point 1 is estimated, and the quality Q _3-1 of the video and audio signal transmitted from point 3 to point 1 is obtained (point-to-point quality Estimation step).

At this time, with respect to the quality factor-point-to-point quality relationship, a subjective quality evaluation experiment is performed in advance using the correspondence between the quality of the video / audio signal transmitted between the points and the quality factor value as the video / audio quality estimation function F1. The model indicating the video / audio quality estimation function F1 may be stored in the storage unit 12.
For example, when the quality factor is packet loss, a video / audio quality estimation function F1 which is a relational expression between the quality Q _nm of the video / audio signal transmitted from the point n to the point m and the packet loss rate L _{nm in the} transmission section is And represented by the following formula (1). Here, nm is a symbol representing a transmission section between two points from point n to point m.
Q _nm = F1 (L _nm ) (1)

An embodiment of a subjective quality evaluation experiment for deriving the video / audio quality estimation function F1 will be described. A multipoint communication system connecting three points shown in FIG. 2 is configured, and packet loss rates between the points are set independently. In this subjective quality evaluation experiment, the video / audio signal method and the display / reproduction method were as follows.
・ Video signal: MPEG4, 1 Mbps, 2 CIF images are displayed in parallel on CRT ・ Audio signal: 7kHz band audio, monaural mixed sound playback through headphones

  In the subjective quality assessment test, 24 people in their 20s and 30s, each with 3 people (1 person at each location), received a “grade 5: very good”, “grade 4: good”, and “grade 3: both The conversation test is evaluated using a five-level quality scale of “I cannot say”, “Score 2: Bad”, and “Score 1: Very Bad”. As subjective quality, the viewing / listening quality when video / audio signals transmitted from two points other than the local point are displayed and reproduced at the local point, and the video / audio transmitted from the point 2 reproduced and displayed at the local point The point-to-point quality of the signal and the point-to-point quality of the video / audio signal transmitted from the point 3 reproduced and displayed at the own point are evaluated. The received / viewing quality and inter-point quality are average values of the evaluator's scores.

The relational expression F1 between the packet loss rate L _nm and the quality Q _nm of the video / audio signal is the relationship between the packet loss rate and the inter-point quality in the transmission section from the point 2 to the point 1, and the packet in the transmission section from the point 3 to the point 1. Obtained from the relationship between loss rate and point-to-point quality. The function type of the video / audio quality estimation function F1 is derived from the least square regression of the packet loss rate and the subjective quality. FIG. 3 shows the correspondence between the packet loss rate and video / audio quality.
Another method for obtaining the relational expression F1 is that the packet loss rate and the reception rate when the packet loss rate in the transmission section from point 2 to point 1 and the packet loss rate in the transmission section from point 3 to point 1 are equal. You may obtain | require from the relationship of viewing quality.

Next, in the arithmetic processing unit 11 of the communication quality estimation apparatus 10, the reception / viewing quality estimation unit 11B obtains the inter-point quality estimation unit 11A based on the inter-point quality-reception / viewing quality relationship in the storage unit 12. The receiving and viewing quality corresponding to the quality Q _2-1 of the video / audio signal transmitted from the point 2 to the point 1 and the quality Q _3-1 of the video / audio signal transmitted from the point 3 to the point 1 is estimated. The reception / viewing quality QL of the video / audio signal to be displayed and reproduced is obtained (reception / viewing quality estimation step).

At this time, with regard to the inter-point quality-reception / viewing quality relationship, the quality Q _nm of the video / audio signal transmitted between the local point and another point and the video / audio signal at a plurality of points are displayed and reproduced at the local point. The received viewing quality QL is modeled in advance as a received viewing quality estimation function F2 expressed by the following equation (2) from a subjective evaluation experiment, and a model indicating the received viewing quality estimation function F2 is stored in the storage unit 12. You just have to.
QL = F2 ( _Q2-1 , _Q3-1 ) (2)

The following formulas (3) and (4) are shown as specific function type examples of the received / viewing quality estimation function F2. a ₁ to a ₈ are constants indicating the degree of influence of the quality Q between each point on the received / viewed quality QL, and are obtained by a method such as least square regression based on the result of the subjective evaluation experiment.
QL = a ₁ Q _2-1 × a ₂ Q _3-1 + a ₃ (3)
QL = (a ₁ Q _2-1 × a ₂ Q _3-1 ) ^1/2 + a ₃ (4)

Expression (3) is a function type that nonlinearly affects the received / viewed quality as a function of the product of the respective inter-point quality, and the inter-point quality value is set to a constant according to the degree of influence on the received / viewed quality. The received / viewing quality QL is calculated by multiplying based on this.
On the other hand, equation (4) is a function type in which the value of the power root between each point to be considered for the product of the respective point quality has a non-linear effect on the receiving and viewing quality. The reception / viewing quality QL is calculated by multiplying based on a constant corresponding to the degree of influence on each reception / viewing quality and obtaining the power root of the multiplication result. At this time, if the number of multiplied quality Q _nm is k (= 2), the k-th root of the multiplication result is obtained.

The reception / viewing quality estimation function F2 uses a least square regression between the reception / viewing quality obtained in the subjective quality evaluation experiment described in the point-to-point quality estimation unit 11A and the point-to-point quality output from the point-to-point quality estimation unit 11A. Derived in advance.
As an example, when Expression (4) is used, FIG. 4 shows a correspondence relationship between the actually measured value of the received / viewed quality and the estimated value of the received / viewed quality obtained from the function F2. The correlation coefficient between the measured value of the received / viewed quality and the estimated value of the received / viewed quality is 0.97, which is a good estimation result.

  As described above, in the present embodiment, the point-to-point quality estimation unit 11A of the arithmetic processing unit 11 calculates the quality factor value related to the video / audio signal transmitted between two arbitrary points and the point-to-point quality for the video / audio signal. Based on the correspondence relationship, the point-to-point quality corresponding to each quality factor value obtained for the video / audio signal transmitted between the local point and each of the two other points during the multipoint communication is estimated and calculated. The reception / viewing quality estimation means 11B of the unit 11 handles the inter-point quality based on the correspondence between the inter-point quality with respect to these video / audio signals and the reception / viewing quality with respect to each video / audio signal displayed and reproduced at the local point. The received and viewed quality is estimated and output as the received and viewed quality at the local location.

  This eliminates the need for the subject to perform subjective assessments for all combinations of quality factors of audio and video signals transmitted between the points, and makes it easy to obtain the own points and each point. It is possible to easily estimate the reception / viewing quality at the local point from the quality factor value regarding the video / audio signal transmitted between the two.

[Second Embodiment]
Next, a communication quality estimation apparatus according to the second embodiment of the present invention will be described with reference to FIG. FIG. 5 is a block diagram showing a configuration of a communication quality estimation apparatus according to the second exemplary embodiment of the present invention.

This communication quality estimation device 20 is composed of an information processing device having a computer as a whole, and each of the others received and reproduced at its own point by multipoint communication based on the correspondence relationship for quality estimation stored in advance in the storage unit Estimate the receiving / viewing quality of the video / audio signal from the point.
In the first embodiment described above, the case where the received / viewing quality is estimated based on the quality factor between the local point and each of the two other points has been described as an example. In the present embodiment, a case will be described in which received / viewed quality is estimated in consideration of three or more other points.

The communication quality estimation device 20 has the same configuration as the communication quality estimation device 10 of FIG. 1, and includes an arithmetic processing unit 21 and a storage unit 22 instead of the arithmetic processing unit 11 and the storage unit 12.
The arithmetic processing unit 21 includes a microprocessor such as a CPU and peripheral circuits thereof, and reads and executes a predetermined program, thereby realizing various functional means by cooperating the hardware and the program.

The arithmetic processing unit 21 has a point-to-point quality estimation unit 21A and a receiving / viewing quality estimation unit 21B as the functional unit.
The point-to-point quality estimation means 21A has a function of estimating the point-to-point quality indicating the communication quality of the video signal from the quality factor value regarding the video / audio signal transmitted between the local point and each other point. .
The reception / viewing quality estimation means 21B estimates the reception / viewing quality when a plurality of video and audio signals transmitted from each point are displayed and reproduced at the own point based on the point-to-point quality obtained by the point-to-point quality estimation unit 21A. It has a function to do.

The storage unit 22 includes a storage device such as a memory or a hard disk, and stores various information and programs used by the arithmetic processing unit 21.
In particular, the storage unit 22 stores, as various information, the correspondence between the quality factor value related to the video / audio signal transmitted between any two points and the quality between the points for the video / audio signal, that is, the quality factor-point-to-point quality relationship. The relationship between the quality between each point for each video / audio signal transmitted between each point and the reception / viewing quality with respect to each video / audio signal displayed and reproduced at its own point, that is, the relationship between the quality between points and reception / viewing quality. Remember.

  In the point-to-point quality estimation means 21A and the reception / viewing quality estimation means 21B of the arithmetic processing unit 21, the quality factor-point-to-point quality relationship and the point-to-point quality-receiving / viewing quality derived in advance and stored in the storage unit 22. Based on the relationship, the inter-point quality and the receiving / viewing quality are estimated.

The communication quality estimation device 20 has an input / output interface unit for exchanging various information with an external device or a storage medium, and an operation / display interface unit for exchanging various information with an operator. However, these configurations are the same as those of a general information processing apparatus such as a personal computer, and detailed description thereof is omitted here.
In addition, the video / audio signal referred to in the present embodiment is a signal including at least both a video signal and an audio signal transmitted between communication terminals.

[Operation of Second Embodiment]
Next, the operation of the communication quality estimation apparatus according to the second embodiment of the present invention will be described with reference to FIG. FIG. 6 is a configuration example of multipoint communication.
In the multipoint communication shown in FIG. 6, the communication terminals 51-54 are arrange | positioned at each of the four points 1-4. Below, the point 1 is made into an own point and the case where the viewing / listening quality at the time of displaying and reproducing | regenerating the audio-video signal from the points 2-4 used as another point is demonstrated by an example is demonstrated.

First, in the arithmetic processing unit 21 of the communication quality estimation apparatus 20, the inter-point quality estimation unit 21 </ b> A determines the video / audio signal transmitted from the point 2 to the point 1 based on the quality factor-inter-point quality relationship in the storage unit 22. The quality Q of the video / audio signal transmitted from the point 2 to the point is estimated by estimating the inter-point quality corresponding to the packet loss rate L _2-1 in the transmission section from the point 2 to the point 1 input as the quality factor value. _2-1 is obtained (point-to-point quality estimation step).

Similarly, the point 3 input as the quality factor value of the video / audio signal transmitted from the point 3 to the point 1 based on the quality factor-point-to-point quality relationship in the storage unit 22 by the point-to-point quality estimation unit 21A. The point-to-point quality corresponding to the packet loss rate L _3-1 in the transmission section from point 1 to point 1 is estimated, and the quality Q _3-1 of the video and audio signal transmitted from point 3 to point 1 is obtained (point-to-point quality Estimation step).

Similarly, from point 4 to point, the point-to-point quality estimation unit 21A inputs the quality factor value of the video / audio signal transmitted from point 4 to point 1 based on the quality factor-point-to-point quality relationship in the storage unit 22. The point-to-point quality corresponding to the packet loss rate L _4-1 in the transmission section to 1 is estimated, and the quality Q _4-1 of the video / audio signal transmitted from the point 4 to the point 1 is obtained (inter-point quality estimation step) ).

The quality factor-point-to-point quality relationship used for the estimation of the point-to-point quality is the same as that in the first embodiment described above, and can be expressed by the above-described equation (1).
Also in the present embodiment, the relationship between the quality of the video / audio signal transmitted between each point and the quality factor value is modeled by conducting a subjective quality evaluation experiment in advance as the video / audio quality estimation function F1. The model indicating the video / audio quality estimation function F <b> 1 may be stored in the storage unit 22.

Next, in the arithmetic processing unit 21 of the communication quality estimation device 20, the reception / viewing quality estimation unit 21B obtains the inter-point quality estimation unit 21A based on the inter-point quality-reception / viewing quality relationship in the storage unit 22. Quality Q _2-1 of video / audio signal transmitted from point 2 to point 1, Quality Q _3-1 of video / audio signal transmitted from point 3 to point 1, and video / audio transmitted from point 4 to point 1 The reception / viewing quality corresponding to the signal quality Q _4-1 is estimated, and the reception / viewing quality QL of the video / audio signal displayed and reproduced at the point 1 is obtained (reception / viewing quality estimation step).

At this time, with regard to the inter-point quality-received / viewed quality relationship, the quality Q _nm of the video / audio signal transmitted between the points and the received / viewed quality QL when the video / audio signals at a plurality of points are displayed and reproduced at the own point. Is previously modeled by subjective evaluation experiments as a reception / viewing quality estimation function F3 represented by the following equation (5), and a model indicating the reception / viewing quality estimation function F3 may be stored in the storage unit 22. .
QL = F3 ( _Q2-1 , _Q3-1 , _Q4-1 ) (5)

The following formulas (6) and (7) are shown as specific function type examples of the received / viewing quality estimation function F3. a ₁ to a ₄ are constants indicating the degree of influence of the quality Q between each point on the received / viewed quality QL, and are obtained by a method such as least square regression based on the result of the subjective evaluation experiment.
QL = a ₁ Q _2-1 × a ₂ Q _3-1 × a ₃ Q _4-1 + a ₄ (6)
QL = (a ₁ Q _2-1 × a ₂ Q _3-1 × a ₃ Q _4-1 ) ^1/3 + a ₄ (7)

Expression (6) is a function type that nonlinearly affects the received / viewed quality as a function of the product of the quality between the points, and the quality value between the points is a constant corresponding to the degree of influence on the received / viewed quality. The received / viewing quality QL is calculated by multiplying based on this.
On the other hand, Equation (7) is a function type in which the value of the power root between each point to be considered for the product of the respective point quality has a non-linear effect on the receiving and viewing quality. The reception / viewing quality QL is calculated by multiplying based on a constant corresponding to the degree of influence on each reception / viewing quality and obtaining the power root of the multiplication result. At this time, if the number of multiplied quality Q _nm is k (= 3), the k-th root of the multiplication result is obtained.

The reception / viewing quality estimation function F3 uses a least-squares regression between the reception / viewing quality obtained in the subjective quality evaluation experiment described in the first embodiment and the point-to-point quality output from the point-to-point quality estimation means 21A. To derive.
As an example, when Expression (6) is used, FIG. 7 shows a correspondence relationship between the actually measured value of the received viewing quality and the estimated value of the received viewing quality obtained from the function F3. The correlation coefficient between the measured value of the received / viewed quality and the estimated value of the received / viewed quality is 0.97, which is a very good estimation result. Also, the reception / viewing quality of multipoint communication connecting five points is estimated in the same manner as in the present embodiment, but the correlation coefficient between the measured value of the reception / viewing quality and the estimated value of the reception / viewing quality is 0.97. Was obtained, and an extremely good estimation result was confirmed.

  Thus, in the present embodiment, the quality factor value relating to the video / audio signal transmitted between any two points and the quality between the points for the video / audio signal by the point-to-point quality estimation means 21A of the arithmetic processing unit 21. Based on the correspondence relationship, the point-to-point quality corresponding to each quality factor value obtained for the video / audio signal transmitted between the own point and each of the three or more other points during the multipoint communication is estimated, The point-to-point quality estimation means 21B of the arithmetic processing unit 21 determines the inter-point quality based on the correspondence between the point-to-point quality for these video and audio signals and the point-and-view quality for each video and audio signal displayed and reproduced at its own point. The received and viewed quality corresponding to is estimated and output as the received and viewed quality at the local location.

  This eliminates the need for the subject to perform subjective evaluations for all combinations of quality factors of the audio-video signal transmitted between the points, and can be easily acquired at the own point and the three or more points. The receiving / viewing quality at the local point can be easily estimated from the quality factor value regarding the video / audio signal transmitted between the other points.

[Extension of each embodiment]
In each of the embodiments described above, the case where the quality factor-point-to-point quality relationship and the point-to-point quality-receiving / viewing quality relationship are respectively formulated by functions has been described as an example. However, the present invention is not limited to this. It may be expressed by a known inference model, for example, an inference model such as fuzzy, neuro, or case base.
In addition, the communication quality estimation apparatus according to each embodiment is provided with means for formulating a quality factor-point-to-point quality relationship and point-to-point quality-received viewing quality relationship with functions, respectively, and a means for generating an inference model. Also good.

Further, the quality factor value is not limited to the packet loss rate, and any value may be used as long as it is a factor related to the quality of the video / audio signal transmitted between arbitrary points. Two or more quality factors may be used in combination.
Specific examples of quality factors include differences in network quality such as packet loss and transmission delay time of video and audio signals transmitted between each point, performance differences between terminal devices installed at each point, and transmission and reception of video and audio signals. Differences in encoding method, encoding method, or transmission method can be mentioned, and values indicating these quality factors may be arbitrarily used.

  Further, in each of the embodiments described above, the case where the communication quality estimation apparatus is provided as an apparatus separate from the communication terminals arranged at each point has been described as an example. However, the communication quality estimation apparatus according to the present invention is described. The configuration, the communication quality estimation method, or the program may be incorporated into any communication terminal.

Further, in each of the embodiments described above, three and four points have been described as examples. However, in the same manner as described above, each of the above-described embodiments also applies to multipoint communication performed at five or more points. Can be applied.
Moreover, about each quality factor value, what was measured with the communication terminal may be notified to a communication quality estimation apparatus via a data communication network, and receiving / viewing quality may be estimated in real time.

Further, in each of the embodiments described above, the quality of the reception / viewing is accurately estimated by using the quality factor value measured in the transmission direction in which the video / audio signal related to the desired reception / viewing quality is transmitted. it can.
At this time, when the same quality factor value is obtained regardless of the transmission direction in the same transmission section, the quality factor value measured in any transmission direction may be used. For example, in the transmission section between two points of point n and point m, if the same quality factor value, here the packet loss rate L _nm = L _mn, is obtained regardless of the transmission direction, Q _nm = F1 (L _nm ) = F1 (L _mn ) = Q _mn

It is a block diagram which shows the structure of the communication quality estimation apparatus concerning the 1st Embodiment of this invention. It is a structural example of the multipoint communication concerning the 1st Embodiment of this invention. It is explanatory drawing which shows the correspondence of a packet loss rate and video / audio quality. It is explanatory drawing which shows the corresponding relationship of receiving / viewing quality (actual value) and receiving / viewing quality (estimated value) in the communication quality estimation apparatus concerning the 1st Embodiment of this invention. It is a block diagram which shows the structure of the communication quality estimation apparatus concerning the 2nd Embodiment of this invention. It is a structural example of the multipoint communication concerning the 2nd Embodiment of this invention. It is explanatory drawing which shows the correspondence of receiving / viewing quality (actual value) and receiving / viewing quality (estimated value) in the communication quality estimation apparatus concerning the 2nd Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Communication quality estimation apparatus, 11 ... Operation processing part, 11A ... Inter-point quality estimation means, 11B ... Reception / viewing quality estimation means, 12 ... Storage part, 20 ... Communication quality estimation apparatus, 21 ... Operation processing part, 21A ... Point Inter-quality estimation means, 21B... Received / viewing quality estimation means, 22.

Claims (5)

Based on the correspondence relationship for quality estimation stored in advance in the storage unit, it is used in a communication quality estimation device that estimates the reception / viewing quality related to video / audio signals from other points received and reproduced at the local point by multipoint communication. A communication quality estimation method,
Based on the correspondence between the quality factor value related to the video / audio signal transmitted between any two points and the quality between the points corresponding to the video / audio signal, stored in the storage unit by the inter-point quality estimation means, A point-to-point quality estimation step for estimating the point-to-point quality corresponding to each quality factor value obtained for the video / audio signal transmitted between the own point and each other point during multipoint communication;
Each inter-point quality for each video / audio signal stored between the local point and each other point and each video / audio displayed and reproduced at the local point, stored in the storage unit, by the received / viewing quality estimation means Reception / viewing quality estimation step for estimating and outputting the reception / viewing quality corresponding to the inter-point quality obtained in the point-to-point quality estimation step based on the correspondence relationship with the reception / viewing quality for the signal as the reception / viewing quality at the local point A communication quality estimation method comprising: and. Based on the correspondence relationship for quality estimation stored in advance in the storage unit, it is used in a communication quality estimation device that estimates the reception / viewing quality related to video / audio signals from other points received and reproduced at the local point by multipoint communication. A communication quality estimation method,
Based on the correspondence between the quality factor value related to the video / audio signal transmitted between any two points and the quality between the points corresponding to the video / audio signal, stored in the storage unit by the inter-point quality estimation means, A point-to-point quality estimation step for estimating the point-to-point quality corresponding to each quality factor value obtained for the video / audio signal transmitted between the own point and each other point during multipoint communication;
The received / viewing quality estimation means multiplies the inter-point quality obtained in the inter-point quality estimation step based on a constant corresponding to the degree of influence on each received / viewed quality, thereby obtaining the received / viewed quality at the own point. A communication quality estimation method comprising: a receiving / viewing quality estimation step to estimate. Based on the correspondence relationship for quality estimation stored in advance in the storage unit, it is used in a communication quality estimation device that estimates the reception / viewing quality related to video / audio signals from other points received and reproduced at the local point by multipoint communication. A communication quality estimation method,
Based on the correspondence between the quality factor value related to the video / audio signal transmitted between any two points and the quality between the points corresponding to the video / audio signal, stored in the storage unit by the inter-point quality estimation means, A point-to-point quality estimation step for estimating the point-to-point quality corresponding to each quality factor value obtained for the video / audio signal transmitted between the own point and each other point during multipoint communication;
The received / viewing quality estimation means multiplies the inter-point quality obtained in the inter-point quality estimation step based on a constant corresponding to the degree of influence on each received / viewed quality, and calculates the power root of the obtained multiplication result A communication quality estimation method, comprising: a reception / viewing quality estimation step for estimating reception / viewing quality at a local point. A communication quality estimation device that estimates reception / viewing quality related to a video / audio signal from each other point received and reproduced at a local point by multipoint communication based on a correspondence relationship for quality estimation stored in advance in a storage unit. And
Based on the correspondence between the quality factor value related to the video / audio signal transmitted between any two points and the quality between the points for the video / audio signal, stored in the storage unit, Point-to-point quality estimation means for estimating the point-to-point quality corresponding to each quality factor value obtained with respect to the video and audio signal transmitted between each other point and each other point;
The inter-point quality for each video / audio signal transmitted between the local point and each other point and the reception / viewing quality for each video / audio signal displayed and reproduced at the local point, stored in the storage unit. Receiving / viewing quality estimation means for estimating and outputting received / viewing quality corresponding to the inter-point quality obtained by the inter-point quality estimation means based on the correspondence relationship as received / viewing quality at its own point, Communication quality estimation device. A computer of a communication quality estimation apparatus that estimates reception / viewing quality related to a video / audio signal from each other point received and reproduced at its own point by multipoint communication based on a correspondence relationship for quality estimation stored in advance in a storage unit In addition,
Based on the correspondence between the quality factor value related to the video / audio signal transmitted between any two points and the quality between the points corresponding to the video / audio signal, stored in the storage unit by the inter-point quality estimation means, A point-to-point quality estimation step for estimating the point-to-point quality corresponding to each quality factor value obtained for the video / audio signal transmitted between the own point and each other point during multipoint communication;
Each inter-point quality for each video / audio signal stored between the local point and each other point and each video / audio displayed and reproduced at the local point, stored in the storage unit, by the received / viewing quality estimation means Reception / viewing quality estimation step for estimating and outputting the reception / viewing quality corresponding to the inter-point quality obtained in the point-to-point quality estimation step based on the correspondence relationship with the reception / viewing quality for the signal as the reception / viewing quality at the local point A program that executes and.

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