Time-correlated ink

1. A system comprising:

one or more processors; and

one or more computer-readable storage media storing computer-executable instructions that, responsive to execution by the one or more processors, cause the system to perform operations including:

displaying previously stored ink input over video content displayed on a display device, the displaying the ink input based on timestamps applied to ink strokes of the ink input, the timestamps temporally correlating the ink input to the video content, each timestamp indicating a playback time for the video content in which the corresponding ink stroke is displayed;

causing an ink stroke of the ink input to visually unwind, the visual unwinding comprising gradually removing the ink stroke from view on the display device as an unwinding animation that imitates a way the ink input corresponding to the ink stroke was received.

2. The system as described in claim 1 , the visually unwinding of the ink stroke comprising a velocity of visually unwinding, the velocity based on the timestamp associated with the ink stroke caused to unwind.

3. The system as described in claim 1 , the visually unwinding of the ink stroke comprising a velocity of visually unwinding, the velocity based on a distance between a start and end of the ink stroke caused to unwind.

4. The system as described in claim 1 , the visually unwinding of the ink stroke comprising a velocity of visually unwinding, the velocity based on a sampling rate of the ink stroke caused to unwind.

5. The system as described in claim 1 , wherein the operations further include:

receiving a rewind input;

rewinding the video content according to the rewind input;

retrieving the ink strokes of the previously stored ink input that are temporally correlated to a portion of the video content; and

rendering the retrieved ink strokes for display on the display device in temporal correlation with the video content such that the ink strokes are displayed in the reverse of the order in which they were received.

6. A computer-implemented method comprising:

receiving ink strokes that are input over video content displayed on a display device;

timestamping and storing the ink strokes to temporally correlate the ink strokes to the video content, wherein a timestamp for an ink stroke indicates a corresponding playback time for the video content in which the ink stroke is applied;

responsive to receiving an indication that input of an ink stroke ceases, causing the ink stroke to visually unwind, the visual unwinding comprising gradually removing the ink stroke from the display device as an unwinding animation that imitates a way the ink stroke was received; and

enabling playback of the ink strokes along with the video content and based on timestamps applied to the ink strokes.

7. The method as described in claim 6 , the visually unwinding comprising a velocity of visually unwinding, the velocity based on at least one of: the timestamp associated with the ink stroke caused to unwind, a distance between a start and end of the ink stroke caused to unwind, or a sampling rate of the ink stroke caused to unwind.

8. The method as described in claim 6 , further comprising:

receiving a rewind input;

rewinding the video content according to the rewind input; and

displaying the ink strokes over the video content in temporal correlation with the video content such that the ink strokes are displayed in the reverse of the order in which they were received.

9. The method as described in claim 6 , further comprising:

playing back a portion of the video content that is temporally correlated to at least some of the ink strokes; and

displaying the at least some of the ink strokes in temporal correlation with the portion of the video content at the same velocity with which the ink strokes were input.

10. A computer-implemented method comprising:

displaying previously stored ink input over video content displayed on a display device, the displaying the ink input based on timestamped ink strokes of the ink input, the timestamps temporally correlating the ink input to the video content, each timestamp indicating a corresponding playback time for the video content in which an ink stroke is displayed;

causing an ink stroke of the ink input to visually unwind, the visual unwinding comprising gradually removing the ink stroke from view on the display device as an unwinding animation that imitates a way the ink input corresponding to the ink stroke was received.

11. The method as described in claim 10 , further comprising grouping at least some of the ink strokes of the ink input into ink objects based on the respective time stamps for the ink strokes.

12. The method as described in claim 10 , further comprising grouping at least some of the ink strokes together based on geometrical clustering between respective ink strokes of the ink input.

13. The method as described in claim 10 , further comprising:

receiving a rewind input;

rewinding the video content according to the rewind input;

retrieving the ink strokes of the previously stored ink input that are temporally correlated to a portion of the video content; and

rendering the retrieved ink strokes for display on the display device in temporal correlation with the video content such that the ink strokes are displayed in the reverse of the order in which they were received.

14. The method as described in claim 10 , further comprising displaying each of the ink strokes of the ink input as an animation rendered at a velocity in which the respective ink stroke was received.

15. The method of claim 8 , wherein the displayed ink strokes are each rendered backward from the end of the ink stroke to the beginning of the ink stroke.

16. The method as described in claim 9 , further comprising:

causing a displayed ink stroke to visually unwind, the visual unwinding comprising gradually removing the ink stroke from view on the display device as an unwinding animation that imitates a way the ink stroke was received.

17. The method as described in claim 16 , the visually unwinding comprising a velocity of visually unwinding, the velocity based on at least one of: the timestamps associated with the ink stroke, a distance between a start and end of the ink stroke or a sampling rate of the ink stroke.

18. The method as described in claim 10 , the visually unwinding of the ink stroke comprising a velocity of visually unwinding, the velocity based on the timestamps associated with the ink stroke caused to unwind.

19. The method as described in claim 10 , the visually unwinding of the ink stroke comprising a velocity of visually unwinding, the velocity based on a distance between a start and end of the ink stroke caused to unwind.

20. The method as described in claim 10 , the visually unwinding of the ink stroke comprising a velocity of visually unwinding, the velocity based on a sampling rate of the ink stroke caused to unwind.