Methods and apparatus to identify media based on watermarks across different audio streams and/or different watermarking techniques

1. An apparatus comprising:

a watermark detector to:

detect a first watermark embedded in a first audio stream associated with media, the first watermark including a first source identifier and a first timing identifier; and

detect a second watermark embedded in a second audio stream associated with the media, the second audio stream different than the first audio stream, the second watermark including a second source identifier and a second timing identifier;

a watermark analyzer to:

determine whether the first and second source identifiers match; and

determine whether the first and second timing identifiers are chronologically congruent;

a controller to associate the first and second watermarks with a media detection event when both (1) the first and second source identifiers match and (2) the first and second timing identifiers are chronologically congruent, the media detection event corresponding to a group of watermarks, the group of watermarks including a threshold number of watermarks, the threshold number being at least two; and

a transmitter to transmit the media detection event to a data collection facility.

2. The apparatus of claim 1 , wherein the controller is not to associate the first and second watermarks with the media detection event when (1) the first and second source identifiers do not match or (2) the first and second timing identifiers are not chronologically congruent.

3. The apparatus of claim 1 , wherein the watermark detector is to (i) assign a first timestamp to the first watermark when the first watermark is detected and (ii) assign a second timestamp to the second watermark when the second watermark is detected, and the controller is to:

associate the first and second watermarks with the media detection event when an interval between the first timestamp and the second timestamp is less than a threshold; and

not associate the first and second watermarks with the media detection event when the interval is greater than the threshold.

4. The apparatus of claim 3 , wherein the controller is not to associate the first and second watermarks with the media detection event when the first timestamp matches the second timestamp.

5. The apparatus of claim 1 , wherein the first watermark is embedded in the first audio stream based on a first watermarking technique, the second watermark is embedded in the second audio stream based on a second watermarking technique, and the watermark detector is to (i) detect the first watermark based on the first watermarking technique and (ii) detect the second watermark based on the second watermarking technique.

6. The apparatus of claim 5 , wherein the watermark detector is to detect a third watermark embedded in the first audio stream based on the second watermarking technique, the third watermark embedded in the first audio stream based on the second watermarking technique.

7. The apparatus of claim 1 , wherein the controller is a first controller, and further including a second controller to:

assign a first series of watermarks to a first monitoring track, the first series of watermarks limited to watermarks embedded in the first audio stream based on a first watermarking technique; and

assign a second series of watermarks to a second monitoring track, the second series of watermarks including watermarks embedded in either the first audio stream or the second audio stream based on the first watermarking technique, both the first and second series of watermarks including the first watermark.

8. The apparatus of claim 7 , wherein the second controller is to assign a third series of watermarks to a third monitoring track, the third series of watermarks including watermarks embedded in either the first audio stream or the second audio stream based on either the first watermarking technique or a second watermarking technique, the third series of watermarks including both the first watermark and the second watermark.

9. The apparatus of claim 1 , wherein the watermark detector is to monitor the first and second audio streams simultaneously.

10. An apparatus comprising:

at least one memory;

computer readable instructions in the apparatus; and

processor circuitry to execute the computer readable instructions to at least:

detect a first watermark embedded in a first audio stream associated with media, the first watermark including a first source identifier and a first timing identifier;

detect a second watermark embedded in a second audio stream associated with the media, the second audio stream different than the first audio stream, the second watermark including a second source identifier and a second timing identifier;

determine whether the first and second source identifiers match;

determine whether the first and second timing identifiers are chronologically congruent relative to first and second times when the respective first and second watermarks were detected;

associate the first and second watermarks with a media detection event when both (1) the first and second source identifiers match and (2) the first and second timing identifiers are chronologically congruent; and

transmit the media detection event to a data collection facility.

11. The apparatus of claim 10 , wherein the processor circuitry is not to associate the first and second watermarks with the media detection event when (1) the first and second source identifiers do not match or (2) the first and second timing identifiers are not chronologically congruent.

12. The apparatus of claim 10 , wherein the processor circuitry is to:

assign a first timestamp to the first watermark when the first watermark is detected;

assign a second timestamp to the second watermark when the second watermark is detected;

associate the first and second watermarks with the media detection event when an interval between the first timestamp and the second timestamp is less than a threshold; and

not associate the first and second watermarks with the media detection event when the interval is greater than the threshold.

13. The apparatus of claim 12 , wherein the processor circuitry is not to associate the first and second watermarks with the media detection event when the first timestamp matches the second timestamp.

14. The apparatus of claim 10 , wherein the first watermark is embedded in the first audio stream based on a first watermarking technique, the second watermark is embedded in the second audio stream based on a second watermarking technique, and the processor circuitry is to (i) detect the first watermark based on the first watermarking technique and (ii) detect the second watermark based on the second watermarking technique.

15. The apparatus of claim 14 , wherein the processor circuitry is to detect a third watermark embedded in the first audio stream based on the second watermarking technique, the third watermark embedded in the first audio stream based on the second watermarking technique.

16. The apparatus of claim 10 , wherein the processor circuitry is to:

assign a first series of watermarks to a first monitoring track, the first series of watermarks limited to watermarks embedded in the first audio stream based on a first watermarking technique; and

assign a second series of watermarks to a second monitoring track, the second series of watermarks including watermarks embedded in either the first audio stream or the second audio stream based on the first watermarking technique, both the first and second series of watermarks including the first watermark.

17. The apparatus of claim 16 , wherein the processor circuitry is to assign a third series of watermarks to a third monitoring track, the third series of watermarks including watermarks embedded in either the first audio stream or the second audio stream based on either the first watermarking technique or a second watermarking technique, the third series of watermarks including both the first watermark and the second watermark.

18. The apparatus of claim 10 , wherein the processor circuitry is to monitor the first and second audio streams simultaneously.

19. The apparatus of claim 10 , wherein the first and second watermarks are to be discarded without being transmitted to the data collection facility when (1) the first and second source identifiers do not match or (2) the first and second timing identifiers are not chronologically congruent.

20. A non-transitory computer readable medium comprising instructions that, when executed, cause a machine to at least:

detect a first watermark embedded in a first audio stream associated with media, the first watermark including a first source identifier and a first timing identifier;

detect a second watermark embedded in a second audio stream associated with the media, the second audio stream different than the first audio stream, the second watermark including a second source identifier and a second timing identifier;

determine whether the first and second source identifiers match;

determine whether the first and second timing identifiers are chronologically congruent;

group the first and second watermarks to form a media detection event when both (1) the first and second source identifiers match and (2) the first and second timing identifiers are chronologically congruent; and

transmit the media detection event to a data collection facility.

21. The non-transitory computer readable medium of claim 20 , wherein the instructions further cause the machine not to group the first and second watermarks to form the media detection event when (1) the first and second source identifiers do not match or (2) the first and second timing identifiers are not chronologically congruent.

22. The non-transitory computer readable medium of claim 20 , wherein the instructions further cause the machine to:

assign a first timestamp to the first watermark when the first watermark is detected;

assign a second timestamp to the second watermark when the second watermark is detected;

group the first and second watermarks to form the media detection event when an interval between the first timestamp and the second timestamp is less than a threshold; and

not group the first and second watermarks to form the media detection event when the interval is greater than the threshold.

23. The non-transitory computer readable medium of claim 22 , wherein the instructions further cause the machine not to group the first and second watermarks to form the media detection event when the first timestamp matches the second timestamp.

24. The non-transitory computer readable medium of claim 20 , wherein the first watermark is embedded in the first audio stream based on a first watermarking technique, the second watermark is embedded in the second audio stream based on a second watermarking technique, and the instructions further cause the machine to (i) detect the first watermark based on the first watermarking technique and (ii) detect the second watermark based on the second watermarking technique.

25. The non-transitory computer readable medium of claim 24 , wherein the instructions further cause the machine to detect a third watermark embedded in the first audio stream based on the second watermarking technique, the third watermark embedded in the first audio stream based on the second watermarking technique.

26. The non-transitory computer readable medium of claim 20 , wherein the instructions further cause the machine to:

assign a first series of watermarks to a first monitoring track, the first series of watermarks limited to watermarks embedded in the first audio stream based on a first watermarking technique; and

assign a second series of watermarks to a second monitoring track, the second series of watermarks including watermarks embedded in either the first audio stream or the second audio stream based on the first watermarking technique, both the first and second series of watermarks including the first watermark.

27. The non-transitory computer readable medium of claim 26 , wherein the instructions further cause the machine to assign a third series of watermarks to a third monitoring track, the third series of watermarks including watermarks embedded in either the first audio stream or the second audio stream based on either the first watermarking technique or a second watermarking technique, the third series of watermarks including both the first watermark and the second watermark.

28. The non-transitory computer readable medium of claim 20 , wherein the instructions further cause the machine to monitor the first and second audio streams simultaneously.