Video Communication Quality Estimation Apparatus, Method, and Program

• US 20090096874A1
• Filed: 09/06/2006
• Published: 04/16/2009
• Est. Priority Date: 09/06/2005
• Status: Active Grant

• Current Assignee: Nippon Telegraph and Telephone Corporation
• Original Assignee: Nippon Telegraph and Telephone Corporation
• Inventors: Yamagishi, Kazuhisa, Hayashi, Takanori
• Granted Patent: US 8,405,773 B2
• Time in Patent Office: Days
• US Class Current: 348/192
• CPC Class Codes: H04N 17/004 for digital television systems
• CPC Class Codes: H04N 5/04 Synchronising for television systems using pulse code modulation H04N7/56

Abstract

A multi-modal quality estimation unit (11) estimates a multi-modal quality value (23A) on the basis of an audio quality evaluation value (21A) and a video quality evaluation value (21). In addition, a delay quality degradation amount estimation unit (12) estimates a delay quality degradation amount (23B) on the basis of an audio delay time (22A) and a video delay time (22B). A video communication quality estimation unit (13) estimates a video communication quality value (24) on the basis of a multi-modal quality value (23A) and a delay quality degradation amount (23B).

Claims

1. A video communication quality estimation apparatus which estimates quality associated with video communication of bidirectionally exchanging an audio medium and a video medium upon compositing the audio medium and the video medium between communication terminals connected via a network, characterized by comprising:

a multi-modal quality estimation unit which estimates a multi-modal quality value as a quality evaluation value of a composite medium obtained by compositing an audio medium output from a communication terminal and a video medium output from the communication terminal on the basis of an audio medium quality evaluation value as a quality evaluation value of the audio medium and a video medium quality evaluation value as a quality evaluation value of the video medium;

a delay quality degradation amount estimation unit which estimates a delay quality degradation amount caused by an audio medium delay and a video medium delay on the basis of an audio delay time as a delay time from input of the audio medium to output of the audio medium between communication terminals and a video delay time as a delay time from input of the video medium to output of the video medium between the communication terminals; and

a video communication quality estimation unit which estimates quality of the video communication on the basis of the multi-modal quality value estimated by said multi-modal quality estimation unit and the delay quality degradation amount estimated by said delay quality degradation amount estimation unit.

2. A video communication quality estimation apparatus according to claim 1, characterized in that said delay quality degradation amount estimation unit includes:

a storage unit which stores, in advance, a delay quality degradation amount estimation model representing a relationship between an audio delay time, a video delay time, and a delay quality degradation amount; and

a delay quality degradation amount calculation unit which calculates a delay quality degradation amount corresponding to the audio delay time and the video delay time on the basis of the delay quality degradation amount estimation model.

3. A video communication quality estimation apparatus according to claim 2, characterized in that the delay quality degradation amount estimation model has a convex characteristic that when the audio delay time is constant, the delay quality degradation amount monotonically increases and reaches a predetermined maximum value with an increase in the video delay time, and monotonically decreases with a further increase in the video delay time, and a convex characteristic that when the video delay time is constant, the delay quality degradation amount monotonically increases and reaches a predetermined maximum value with an increase in the audio delay time, and monotonically decreases with a further increase in the audio delay time.

4. A video communication quality estimation apparatus according to claim 1, characterized in that said delay quality degradation amount estimation unit includes:

an absolute delay quality degradation amount calculation unit which calculates an absolute delay quality degradation amount originating from an absolute delay of the audio medium and an absolute delay of the video medium on the basis of the audio delay time and the video delay time;

a relative delay quality degradation amount calculation unit which calculates a relative delay quality degradation amount originating from a relative delay between the audio medium and the video medium on the basis of the audio delay time and the video delay time; and

a delay quality degradation amount calculation unit which calculates the delay quality degradation amount on the basis of the absolute delay quality degradation amount and the relative delay quality degradation amount.

5. A video communication quality estimation apparatus according to claim 4, characterized in that said delay quality degradation amount estimation unit includes a storage unit which stores, in advance, an absolute delay quality degradation amount estimation model representing a characteristic that an absolute delay quality degradation amount monotonically increases with an increase in a delay time sum of an audio delay time and a video delay time, and

said delay quality degradation amount estimation unit calculates an absolute delay quality degradation amount corresponding to a delay time sum of the audio delay time and the video delay time on the basis of the absolute delay quality degradation amount estimation model.

6. A video communication quality estimation apparatus according to claim 4, characterized in that

said delay quality degradation amount estimation unit includes a storage unit which stores, in advance, a relative delay quality degradation amount estimation model representing a characteristic that a relative delay quality degradation amount monotonically increases with an increase in a delay time difference between an audio delay time and a video delay time, and

said relative delay quality degradation amount estimation unit derives a relative delay quality degradation amount corresponding to a delay time difference between the audio delay time and the video delay time on the basis of the relative delay quality degradation amount estimation model, and outputs the relative delay quality degradation amount.

7. A video communication quality estimation apparatus according to claim 6, characterized in that

said storage unit stores a plurality of relative delay quality degradation amount estimation models corresponding to a relationship in magnitude between an audio delay time and a video delay time, and

said relative delay quality degradation amount estimation unit selects a relative delay quality degradation amount estimation model corresponding to a relationship in magnitude between the audio delay time and the video delay time from said storage unit, and calculates a relative delay quality degradation amount corresponding to a delay time difference between the audio delay time and the video delay time on the basis of the selected relative delay quality degradation amount estimation model.

8. A video communication quality estimation apparatus according to claim 1, characterized in that said delay quality degradation amount estimation unit includes:

an absolute delay quality degradation amount estimation unit which estimates an absolute delay quality degradation amount originating from an absolute delay of the audio medium and an absolute delay of the video medium on the basis of the audio delay time and the video delay time; and

a relative delay quality degradation amount estimation unit which estimates a relative delay quality degradation amount originating from a relative delay between the audio medium and the video medium on the basis of the audio delay time, the video delay time, an a frame rate of the video medium.

9. A video communication quality estimation apparatus according to claim 8, characterized in that

said delay quality degradation amount estimation unit includes:

a storage unit which stores, in advance, a relative delay quality degradation amount estimation model comprising a linear function representing a delay time difference—

relative delay quality degradation amount characteristic that a relative delay quality degradation amount monotonically increases with an increase in a delay time difference between an audio delay time and a video delay time, and a slope coefficient estimation model representing a slope coefficient characteristic that a slope coefficient of the linear function increases in a logarithmic function manner with an increase in frame rate; and

a slope coefficient calculation unit which calculates a slope coefficient of the linear function corresponding to a frame rate of the video medium on the basis of the slope coefficient estimation model, and

said relative delay quality degradation amount estimation unit calculates a relative delay quality degradation amount corresponding to a delay time difference between the audio delay time and the video delay time on the basis of the relative delay quality degradation amount estimation model specified by the slope coefficient.

10. A video communication quality estimation apparatus according to claim 9, characterized in that

said storage unit stores a plurality of relative delay quality degradation amount estimation models and a plurality of coefficient estimation models which correspond to a relationship in magnitude between an audio delay time and a video delay time,

said slope coefficient calculation unit selects a slope coefficient estimation model corresponding to the relationship in magnitude between the audio delay time and the video delay time from said storage unit, and calculates the slope coefficient on the basis of the selected slope coefficient estimation model, and

said relative delay quality degradation amount estimation unit specifies a slope from the selected slope coefficient by selecting a relative delay quality degradation amount estimation model corresponding to the relationship in magnitude between the audio delay time and the video delay time from said storage unit, and calculates a relative delay quality degradation amount corresponding to a delay time difference between the audio delay time and the video delay time on the basis of the obtained relative delay quality degradation amount estimation model.

11. A video communication quality estimation apparatus according to claim 1, characterized in that said video communication quality calculation unit includes:

a storage unit which stores, in advance, a video communication quality estimation model representing a relationship between a multi-modal quality value, a delay quality degradation amount, and a video communication quality value; and

a video communication quality calculation unit which calculates a video communication quality value corresponding to a multi-modal quality value and a delay quality degradation amount on the basis of the video communication quality estimation model.

12. A video communication quality estimation method used for a video communication quality estimation apparatus which estimates quality associated with video communication of bidirectionally exchanging an audio medium and a video medium upon compositing the audio medium and the video medium between communication terminals connected via a network, characterized by comprising:

the multi-modal quality estimation step of causing a multi-modal quality estimation unit to estimate a multi-modal quality value as a quality evaluation value of a composite medium obtained by compositing an audio medium output from a communication terminal and a video medium output from the communication terminal on the basis of an audio medium quality evaluation value as a quality evaluation value of the audio medium and a video medium quality evaluation value as a quality evaluation value of the video medium;

the absolute delay quality degradation amount estimation step of causing a delay quality degradation amount estimation unit to estimate a delay quality degradation amount caused by an audio medium delay and a video medium delay on the basis of an audio delay time as a delay time from input of the audio medium to output of the audio medium between communication terminals and a video delay time as a delay time from input of the video medium to output of the video medium between the communication terminals; and

the video communication quality estimation step of causing a video communication quality estimation unit to estimate quality of the video communication on the basis of the multi-modal quality value estimated by the multi-modal quality estimation unit and the delay quality degradation amount estimated by the delay quality degradation amount estimation unit.

13. A program which causes a computer of a video communication quality estimation apparatus which estimates quality associated with video communication of bidirectionally exchanging an audio medium and a video medium upon compositing the audio medium and the video medium between communication terminals connected via a network to execute:

the multi-modal quality estimation step of causing a multi-modal quality estimation unit to estimate a multi-modal quality value as a quality evaluation value of a composite medium obtained by compositing an audio medium output from a communication terminal and a video medium output from the communication terminal on the basis of an audio medium quality evaluation value as a quality evaluation value of the audio medium and a video medium quality evaluation value as a quality evaluation value of the video medium;

the absolute delay quality degradation amount estimation step of causing a delay quality degradation amount estimation unit to estimate a delay quality degradation amount caused by an audio medium delay and a video medium delay on the basis of an audio delay time as a delay time from input of the audio medium to output of the audio medium between communication terminals and a video delay time as a delay time from input of the video medium to output of the video medium between the communication terminals; and

the video communication quality estimation step of causing a video communication quality estimation unit to estimate quality of the video communication on the basis of the multi-modal quality value estimated by the multi-modal quality estimation unit and the delay quality degradation amount estimated by the delay quality degradation amount estimation unit.