Methods and apparatus for crediting a media presentation device

1. An apparatus comprising:

means for computing a signature from audio obtained from a media device during a time period;

means for determining an on/off state of the media device based on a gain level applied by an automatic gain controller during collection of the audio; and

means for crediting the media device with presenting media during the time period when (1) the signature matches at least one of a set of reference signatures and the on/off state determined for the media device is an on state, and (2) when the signature matches at least one of the set of reference signatures and the on/off state determined for the media device is an off state, the means for crediting to not credit the media device with presenting the media during the time period when (3) the signature does not match at least one of the set of reference signatures and the on/off state determined for the media device is the off state.

2. The apparatus as defined in claim 1 , wherein the audio is recorded with a microphone at a monitored location.

3. The apparatus as defined in claim 1 , wherein the audio is included in a data file received from the media device.

4. The apparatus as defined in claim 1 , wherein the means for computing is to generate multiple signatures for the time period.

5. The apparatus as defined in claim 1 , further including means for detecting encoded information present in the audio obtained for the time period when the signature does not match at least one of the set of reference signatures, the means for crediting to credit the media device with presenting media during the time period when the means for detecting detects the encoded information irrespective of the determination of the on/off state, and the means for crediting not to credit the media device with presenting the media during the time period when the means for detecting does not detect the encoded information and the on/off state determined for the media device is the off state.

6. The apparatus as defined in claim 5 , wherein the means for detecting is to detect the encoded information based on extracting a steganographically encoded watermark from the audio.

7. An apparatus comprising:

a code detector to detect whether encoded information is presenting audio obtained from a media device during a time period;

an on/off detector to determine an on/off state of the media device based on a gain level applied by an automatic gain controller to collect the audio; and

a location creditor to credit the media device with presenting media during the time period when the encoded information is detected and the on/off state is determined to be an on state, the location creditor to credit the media device with presenting media during the time period when the encoded information is detected and the on/off state is determined to be an off state, the location creditor not to credit the media device with presenting the media during the time period when the encoded information is not detected and the on/off state determined for the media device is the off state.

8. The apparatus of claim 7 , wherein the audio is recorded with a microphone at a monitored location.

9. The apparatus of claim 7 , wherein the audio is included in a data file received from the media device.

10. The apparatus of claim 7 , wherein the code detector is to detect the encoded information based on extracting a steganographically encoded watermark from the audio.

11. The apparatus of claim 7 , further including a signature generator, wherein when the encoded information is not detected:

the signature generator is to generate a signature of the audio and attempt to match the generated signature to a set of reference signatures;

the location creditor is to credit the media device with presenting media during the time period when the generated signature match at least one of the reference signatures irrespective of the determination of the on/off state; and

the location creditor is not to credit the media device with presenting the media during the time period when the generated signature does not match at least one of the reference signatures and the on/off state determined for the media device is the off state.

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

obtain a file including audio collected for a time period by an audience measurement device monitoring a media presentation device at a monitored location remote from a back office, the file identifying a gain level applied to collect the audio;

determine the media presentation device was in an off state during the time period based on the gain level;

analyze the audio for encoded information;

at least when the encoded information is not present in the audio, generate a signature based on the audio and attempt to match the signature to a set of reference signatures;

if either the encoded information is present in the audio or the signature matches at least one of the reference signatures:

override the determination that the media presentation device was in the off state; and

credit the media presentation device with presenting media corresponding to at least one of the encoded information or the signature during the time period.

13. The non-transitory computer readable medium as defined in claim 12 , wherein the audio is recorded at the monitored location.

14. The non-transitory computer readable medium as defined in claim 12 , wherein the audio is stored in a data file.

15. The non-transitory computer readable medium as defined in claim 12 , wherein the instructions cause the processor to detect the encoded information by extracting a steganographically encoded watermark.

16. The non-transitory computer readable medium as defined in claim 12 , wherein the instructions cause the processor to override the determination that the media presentation device was in the off state based only on the audio.