Management of presentation time in a digital media presentation system with variable rate presentation capability

1. A method, performed by at least one machine, for rendering temporal sequence presentation data in a machine-implemented rendering system, the temporal sequence presentation data being tangibly stored in a first computer-readable medium, the method comprising steps of:

(A) maintaining a value of a presentation time parameter tangibly stored in a second computer-readable medium and representing an amount of time elapsed during rendering of a portion of the temporal sequence presentation data;

(B) providing the value of the presentation time parameter to a first component of the rendering system;

(C) maintaining a value of a data time parameter tangibly stored in a third computer-readable medium and representing an amount of time required by the rendering system to render the portion of the temporal sequence presentation data at a default presentation rate; and

(D) providing the value of the data time parameter to a second component of the rendering system;

wherein the value of the presentation time parameter is not equal to the value of the data time parameter.

2. The method of claim 1 , wherein the first component and the second component are the same component of the rendering system.

3. The method of claim 1 , wherein the step (B) comprises a step of providing the presentation time parameter value in response to a request from the first component for a current time.

4. The method of claim 1 , wherein the step (D) comprises a step of providing the data time parameter value in response to a request from the second component for a current time.

5. The method of claim 1 , wherein the step (C) comprises steps of:

(C)(1) identifying a number of elements in the portion of the temporal sequence presentation data;

(C)(2) identifying a rendition period required by the rendering system to render one of the elements in the portion of the temporal sequence presentation data; and

(C)(3) maintaining a product of the number of elements multiplied by the identified rendition period as the data time parameter value in the third computer-readable medium.

6. The method of claim 1 , wherein the step (C) comprises steps of:

(C)(1) for each element in the portion of the temporal sequence presentation data:

(a) identifying a default rendition period of the element; and

(C)(2) maintaining a sum of the identified default rendition periods as the data time parameter value in the third computer-readable medium.

7. The method of claim 1 , wherein the step (C) comprises steps of:

(C)(1) for each element in the portion of the temporal sequence presentation data:

(a) identifying an actual rendition period of the element;

(b) identifying an actual presentation rate of the element;

(c) multiplying the actual rendition period of the element by the actual presentation rate of the element to produce a product;

(C)(2) maintaining a sum of the products produced by step (C) (1) as the data time parameter value in the third computer-readable medium.

8. The method of claim 1 , wherein the step (C) comprises steps of:

identifying, as the value of the data time parameter, a time integral of a presentation rate of the portion over the amount of time elapsed during rendering of the portion by the rendering system, wherein the presentation rate is equal to the ratio of a change in the value of the data time parameter over time to a change in the value of the presentation time parameter over time; and

maintaining the value of the data time parameter in the third computer-readable medium.

9. The method of claim 1 , wherein the step (A) comprises steps of:

(A)(1) for each element in the portion of the temporal sequence presentation data:

(a) identifying a default rendition period of the element;

(b) identifying an actual presentation rate of the element;

(c) dividing the default rendition period of the element by the actual presentation rate of the element to produce a quotient; and

(A)(2) maintainiing a sum of the quotients produced by step (A)(1) as the presentation time parameter value in the second computer-readable medium.

10. The method of claim 1 , wherein the step (B) comprises steps of:

(B)(1) receiving an explicit request for the value of the presentation time parameter; and

(B)(2) providing the value of the presentation time parameter in response to the request.

11. The method of claim 1 , wherein the step (D) comprises steps of:

(D)(1) receiving an explicit request for the value of the data time parameter; and

(D)(2) providing the value of the data time parameter in in response to the request.

12. A method, performed by at least one machine, for rendering temporal sequence presentation data in a machine-implemented rendering system, the temporal sequence presentation data being tangibly stored in a first computer-readable medium, the method comprising steps of:

(A) receiving a request from a first component of the rendering system for a first current time;

(B) maintaining a value of a presentation time parameter tangibly stored in a second computer-readable medium and representing an amount of time elapsed during rendering of a portion of the temporal sequence presentation data by the rendering system;

(C) providing the value of the presentation time parameter to the first component in response to the request;

(D) receiving a request from a second component of the rendering system for a second current time;

(E) maintaining a value of a data time parameter tangibly stored in a third computer-readable medium and representing an amount of time required to render the portion of the temporal sequence presentation data at a default presentation rate; and

(F) providing the value of the data time parameter to the second component in response to the request;

wherein the value of the presentation time parameter is not equal to the value of the data time parameter.

13. A device for rendering temporal sequence presentation data in a machine-implemented rendering system, the temporal sequence presentation data being tangibly stored in a first computer-readable medium, the device comprising at least one processor and at least one second computer-readable medium tangibly storing computer program instructions for:

maintaining a value of a presentation time parameter tangibly stored in a third computer-readable medium and representing an amount of time elapsed during rendering of a portion of the temporal sequence presentation data by the rendering system;

providing the value of the presentation time parameter to a first component of the rendering system;

maintaining a value of a data time parameter that is not equal to the value of the presentation time parameter and which represents an amount of time required by the rendering system to render the portion of the temporal sequence presentation data at a default presentation rate, the data time parameter being tangibly stored in a fourth computer-readable medium; and

providing the value of the data time parameter to a second component of the rendering system.

14. The device of claim 13 , wherein the first component and the second component are the same component of the rendering system.

15. The device of claim 13 , wherein the instructions for maintaining the value of the data time parameter comprise instructions for:

identifying a number of elements in the portion of the temporal sequence presentation data;

identifying a rendition period required by the rendering system to render one of the elements in the portion of the temporal sequence presentation data;

maintaining a product of the number of elements multiplied by the identified rendition period as the data time parameter value in the fourth computer-readable medium.

16. The device of claim 13 , wherein the instructions for maintaining the value of the data time parameter comprise instructions for:

for each element in the portion of the temporal sequence presentation data:

identifying a default rendition period of the element;

maintaining a sum of the identified default rendition periods as the data time parameter value in the fourth computer-readable medium.

17. The device of claim 13 , wherein the instructions for maintaining the value of the data time parameter comprise instructions for:

for each element in the portion of the temporal sequence presentation data:

identifying an actual rendition period of the element;

identifying an actual presentation rate of the element;

multiplying the actual rendition period of the element by the actual presentation rate of the element to produce a product;

maintaining a sum of the products as the data time parameter value in the third computer-readable medium.

18. The device of claim 13 , wherein the instructions for maintaining the value of the data time parameter comprise instructions for:

identifying, as the value of the data time parameter, a time integral of a presentation rate of the portion over the amount of time elapsed during rendering of the portion by the rendering system, wherein the presentation rate is equal to the ratio of a change in the value of the data time parameter over time to a change in the value of the presentation time parameter over time; and

maintaining the value of the data time parameter in the fourth computer-readable medium.

19. The device of claim 13 , wherein the instructions for maintaining the value of the presentation time parameter comprise instructions for:

for each element in the portion of the temporal sequence presentation data:

identifying a default rendition period of the element;

identifying an actual presentation rate of the element;

dividing the default rendition period of the element by the actual presentation rate of the element to produce a quotient;

providing a sum of the quotients as the presentation time parameter value in the third computer-readable medium.

20. The device of claim 13 , wherein the instructions for providing the value of the presentation time parameter comprise instructions for:

receiving an explicit request for the value of the presentation time parameter; and

providing the value of the presentation time parameter in response to the request.

21. The device of claim 13 , wherein the instructions for providing the value of the data time parameter comprise instructions for:

receiving an explicit request for the value of the data time parameter; and

providing the value of the data time parameter in response to the request.

22. A device for rendering temporal sequence presentation data in a machine-implemented rendering system, the temporal sequence presentation data being tangibly stored in a first computer-readable medium, the device comprising at least one processor and at least one second computer-readable medium tangibly storing computer program instructions for:

receiving a request from a first component of the rendering system for a first current time;

maintaining a value of a presentation time parameter tangibly stored in a third computer-readable medium and representing an amount of time elapsed during rendering of a portion of the temporal sequence presentation data by the rendering system;

providing the value of the presentation time parameter to the first component in response to the request;

receiving a request from a second component of the rendering system for a second current time;

maintaining a value of a data time parameter that is not equal to the value of the presentation time parameter and which represents an amount of time required to render the portion of the temporal sequence presentation data at a default presentation rate, the data time parameter being tangibly stored in a fourth computer-readable medium; and

providing the value of the data time parameter to the second component in response to the request.