Method and method for shortening video with event preservation

1. A method of shortening a video, the method comprising:

determining shortened key frames by selecting one key frame, for every preset time interval on a time line of the video or for every preset position interval of a camera which captures the video, from among original key frames of the video;

determining event key frames from which an event is detected, from among the original key frames;

determining event-preserved key frames using the shortened key frames and the event key frames; and

generating a shortened video using the event-preserved key frames.

2. The method of claim 1 , the generating comprises correcting a position of each of the event-preserved key frames on a timeline of the shortened video to reduce a change in camera position between two adjacent event-preserved key frames based on camera positions corresponding to the event-preserved key frames.

3. The method of claim 1 , the generating comprises selecting to-be-reproduced key frames, which are included in the shortened video, from among the event-preserved key frames so that a number of the to-be-reproduced key frames corresponds to a video reproduction speed.

4. The method of claim 1 , wherein the determining of the event key frames comprises determining key frames in which a motion of a foreground is detected, from among the original key frames, as the event key frames.

5. The method of claim 1 , wherein the determining of the event key frames comprises determining key frames satisfying a preset event condition from among the original key frames as the event key frames.

6. The method of claim 1 , wherein the determining of the shortened key frames comprises selecting one key frame among one or more original key frames which are captured at camera positions within each preset position interval.

7. The method of claim 6 , wherein the determining of the shortened key frames comprises:

detecting a motion of a background in the original key frames; and

calculating camera positions corresponding to the original key frames based on the motion of the background.

8. The method of claim 7 , wherein the determining of the shortened key frames comprises detecting a motion of a foreground and a motion of a background in the original key frames, and

wherein the determining of the event key frames comprises determining key frames in which the motion of the foreground is detected, from among the original key frames, as the event key frames.

9. The method of claim 3 , further comprising, when the video reproduction speed is changed during reproduction of the shortened video, reselecting the to-be-reproduced key frames from among the event-preserved key frames that come after a time point when the video reproduction speed has been changed on a time line of the shortened video so that a number of the reselected to-be-reproduced key frames corresponds to the changed video reproduction speed.

10. The method of claim 1 , wherein the generating comprises performing image rendering based on the event-preserved key frames.

11. The method of claim 1 , wherein the determining of the event-preserved key frames comprises:

determining camera positions corresponding to the shortened key frames and camera positions corresponding to the event key frames; and

determining the duplicate key frames from among the shortened key frames, camera positions of the duplicate key frames existing within a preset range from camera positions of the event key frames.

12. An apparatus for shortening a video, the apparatus comprising:

at least one processor configured to implement:

a shortened key frame determiner configured to determine shortened key frames by selecting one key frame, for every preset time interval on a time line of the video or for every preset position interval of a camera which captures the video, from among original key frames of the video;

an event key frame determiner configured to determine event key frames from which an event is detected, from among the original key frames;

an event-preserved key frame determiner configured to determine event-preserved key frames using the shortened key frames and the event key frames; and

a video generator configured to generate a shortened video using the event-preserved key frames.

13. The apparatus of claim 12 , wherein the at least one processor is further configured to implement a key frame position corrector configured to correct a position of each of the event-preserved key frames on a timeline of the shortened video to reduce a change in camera position between two adjacent event-preserved key frames based on camera positions corresponding to the event-preserved key frames.

14. The apparatus of claim 12 , wherein the at least one processor is further configured to implement a to-be-reproduced key frame selector configured to select to-be-reproduced key frames, which are included in the shortened video, from among the even-preserved key frames so that a number of the to-be-reproduced key frames corresponds to a video reproduction speed.

15. The apparatus of claim 12 , wherein the event key frame determiner determines key frames in which a motion of a foreground is detected, from among the original key frames, as the event key frames.

16. The apparatus of claim 12 , wherein the event key frame determiner determines key frames satisfying a preset event condition from among the original key frames as the event key frames.

17. The apparatus of claim 12 , wherein the shortened key frame determiner selects one key frame among one or more original key frames which are captured at camera positions within each preset position interval.

18. The apparatus of claim 17 , wherein the shortened key frame determiner detects a motion of a background in the original key frames and calculates camera positions corresponding to the original key frames based on the motion of the background.

19. The apparatus of claim 18 , wherein the shortened key frame determiner detects a motion of a foreground and a motion of a background in the original key frames, and

wherein the event key frame determiner determines key frames in which the motion of the foreground is detected, from among the original key frames, as the event key frames.

20. The apparatus of claim 14 , wherein when the video reproduction speed is changed during reproduction of the shortened video,

the to-be-reproduced key frame selector reselects the to-be-reproduced key frames from among the event-preserved key frames that come after a time point when the video reproduction speed has been changed on a time line of the shortened video so that a number of the reselected to-be-reproduced key frames corresponds to the changed video reproduction speed.