Reducing signature matching uncertainty in media monitoring systems

1. A media monitoring method comprising:

executing a media signature matching procedure, by executing an instruction with a processor, using a first analysis time window on monitored media signatures representative of monitored media to identify the monitored media, the media signature matching procedure to compare groups of neighboring monitored media signatures with respective groups of neighboring reference signatures representative of respective different reference media sources to determine first matching results, the first analysis time window defining a first size of the groups of neighboring monitored media signatures and of the groups of neighboring reference signatures to be compared by the media signature matching procedure, wherein a first one of the first matching results is determined by comparing a first group of neighboring monitored signatures spanning a duration corresponding to the first analysis time window to respective ones of the groups of neighboring reference signatures representative of the respective different reference media sources to determine respective signature comparison values corresponding to the different reference media sources;

determining, by executing an instructions with the processor, the first matching results are indicative of a matching uncertainty condition when the first one of the first matching results indicates multiple reference media sources have respective signature comparison values that satisfy a comparison threshold; and

in response to determining the first matching results obtained from executing the media signature matching procedure using the first analysis time window are indicative of the matching uncertainty condition, outputting second matching results obtained from executing, with the processor, the media signature matching procedure on the monitored media signatures using a second analysis time window defining a second size of the groups of neighboring monitored media signatures and of the groups of neighboring reference signatures to be compared by the media signature matching procedure, the second analysis time window being larger than the first analysis time window to reduce matching uncertainty associated with performing the media signature matching procedure on the monitored media signatures.

2. The method as defined in claim 1 , further including outputting the first matching results obtained from executing the media signature matching procedure using the first analysis time window in response to determining the first matching results are not indicative of the matching uncertainty condition.

3. The method as defined in claim 2 , further including executing the media signature matching procedure using the first analysis time window in parallel with executing the media signature matching procedure using the second analysis time window.

4. The method as defined in claim 1 , further including:

examining, over a first observation period, reference timestamps associated with consecutive ones of the first matching results obtained from executing the media signature matching procedure using the first analysis time window; and

determining the first matching results are indicative of the matching uncertainty condition when the reference timestamps are discontinuous in the first observation period.

5. The method as defined in claim 4 , further including determining the reference timestamps are discontinuous in the first observation period when, over the first observation period, successive ones of the reference timestamps do not increment relative to preceding ones of the reference timestamps by a first amount within a range based on a time resolution associated with the first matching results.

6. The method as defined in claim 1 , wherein the first analysis time window is substantially equal to four (4) seconds, and the second analysis time window is substantially equal to thirty-two (32) seconds.

7. A non-transitory computer readable medium comprising computer readable instructions which, when executed, cause a processor to at least:

execute a media signature matching procedure with a first analysis time window on monitored media signatures representative of monitored media to identify the monitored media, the media signature matching procedure to compare groups of neighboring monitored media signatures with respective groups of neighboring reference signatures representative of respective different reference media sources to determine first matching results, the first analysis time window defining a first size of the groups of neighboring monitored media signatures and of the groups of neighboring reference signatures to be compared by the media signature matching procedure, wherein a first one of the first matching results is determined by comparing a first group of neighboring monitored signatures spanning a duration corresponding to the first analysis time window to respective ones of the groups of neighboring reference signatures representative of the respective different reference media sources to determine respective signature comparison values corresponding to the different reference media sources;

determine the first matching results are indicative of a matching uncertainty condition when the first one of the first matching results indicates multiple reference media sources have respective signature comparison values that satisfy a comparison threshold; and

in response to determining the first matching results obtained from performing the media signature matching procedure with the first analysis time window are indicative of the matching uncertainty condition, output second matching results obtained from executing the media signature matching procedure on the monitored media signatures with a second analysis time window defining a second size of the groups of neighboring monitored media signatures and of the groups of neighboring reference signatures to be compared by the media signature matching procedure, the second analysis time window being larger than the first analysis time window to reduce matching uncertainty associated with performing the media signature matching procedure on the monitored media signatures.

8. The non-transitory computer readable medium as defined in claim 7 , wherein the computer readable instructions, when executed, further cause the processor to output the first matching results obtained from executing the media signature matching procedure with the first analysis time window in response to determining the first matching results are not indicative of the matching uncertainty condition.

9. The non-transitory computer readable medium as defined in claim 8 , wherein the computer readable instructions, when executed, further cause the processor to execute the media signature matching procedure with the first analysis time window in parallel with executing the media signature matching procedure with the second analysis window.

10. The non-transitory computer readable medium as defined in claim 7 , wherein the computer readable instructions, when executed, further cause the processor to:

examine, over a first observation period, reference timestamps associated with consecutive ones of the first matching results obtained from executing the media signature matching procedure with the first analysis time window; and

determine the first matching results are indicative of the matching uncertainty condition when the reference timestamps are discontinuous in the first observation period.

11. The non-transitory computer readable medium as defined in claim 10 , wherein the computer readable instructions, when executed, further cause the processor to determine the reference timestamps are discontinuous in the first observation period when, over the first observation period, successive ones of the reference timestamps do not increment relative to preceding ones of the reference timestamps by a first amount within a range based on a time resolution associated with the first matching results.

12. The non-transitory computer readable medium as defined in claim 7 , wherein the first analysis time window is substantially equal to four (4) seconds, and the second analysis time window is substantially equal to thirty-two (32) seconds.

13. A media signature comparison apparatus comprising:

a first media signature comparator to execute media signature matching with a first analysis time window on monitored media signatures representative of monitored media to identify the monitored media, the media signature matching to compare groups of neighboring monitored media signatures with respective groups of neighboring reference signatures representative of respective different reference media sources, the first analysis time window defining a first size of the groups of neighboring monitored media signatures and of the groups of neighboring reference signatures to be compared by the media signature matching procedure, wherein the first media signature comparator is further to determine a first one of the first matching results by comparing a first group of neighboring monitored signatures spanning a duration corresponding to the first analysis time window to respective ones of the groups of neighboring reference signatures representative of the respective different reference media sources to determine respective signature comparison values corresponding to the different reference media sources;

a second media signature comparator to execute the media signature matching with a second analysis window on the monitored media signatures representative of the monitored media to identify the monitored media, the second analysis window defining a second size of the groups of neighboring monitored media signatures and of the groups of neighboring reference signatures to be compared by the media signature matching, the second analysis window being larger than the first analysis window to reduce matching uncertainty associated with performing the media signature matching on the monitored media signatures; and

a matching results selector to select whether to output first matching results obtained from the first media signature comparator or to output second matching results obtained from the second media signature comparator depending on whether the first matching results are indicative of a matching uncertainty condition, wherein the matching results selector is further to determine the first matching results are indicative of the matching uncertainty condition when the first one of the first matching results indicates multiple reference media sources have respective signature comparison values that satisfy a comparison threshold.

14. The apparatus as defined in claim 13 , wherein the matching results selector is further to:

select the second matching results in response to determining the first matching results are indicative of the matching uncertainty condition; and

select the first matching results in response to determining the first matching results are not indicative of the matching uncertainty condition.

15. The apparatus as defined in claim 13 , wherein the first media signature comparator and the second media signature comparator operate in parallel.

16. The apparatus as defined in claim 13 , wherein the matching results selector is further to:

examine, over a first observation period, reference timestamps associated with consecutive ones of the first matching results obtained from the first media signature comparator; and

determine the first matching results are indicative of the matching uncertainty condition when the reference timestamps are discontinuous in the first observation period.

17. The apparatus as defined in claim 16 , wherein the matching results selector is further to determine the reference timestamps are discontinuous in the first observation period when, over the first observation period, successive ones of the reference timestamps do not increment relative to preceding ones of the reference timestamps by a first amount within a range based on a time resolution associated with the first matching results.