Methods and apparatus to generate signatures representative of media

Patent metadata

Field	Value
Publication number	US-9548830-B2
Application number	US-201414512663-A
Country	US
Kind code	B2
Filing date	Oct 13, 2014
Priority date	Sep 5, 2014
Publication date	Jan 17, 2017
Grant date	Jan 17, 2017

Abstract

Methods and apparatus to generate signatures representative of media are disclosed. An example method includes transforming a block of samples from a time-domain representation to a frequency-domain representation comprising multiple frequency bands, determining a signature function by fitting a curve to at least a subset of the frequency bands, and calculating signature values for the block. Calculating the tuple includes calculating a first angle between a reference line and a first line that is tangent to the signature function at a first index, calculating a second angle between the reference line and a second line that is tangent to the signature function at a second index, calculating a third angle between the reference line and a third line that is tangent to the signature function at a third index, and creating the signature values based on the first angle, the second angle, and the third angle.

First claim

What is claimed is:

1. A method to generate a signature of a signal, comprising:
transforming a block of signal samples from a time-domain representation to a frequency-domain representation including multiple frequency bands;
determining a signature function by fitting a curve to at least a subset of the frequency bands; and
calculating signature values for the block of signal samples by:
calculating a first angle between a reference line and a first tangent line that is tangent to the signature function at a first index value in a set of index values over which the signature function is defined;
calculating a second angle between the reference line and a second tangent line that is tangent to the signature function at a second index value in the set of index values;
calculating a third angle between the reference line and a third tangent line that is tangent to the signature function at a third index value in the set of index values; and
creating the signature values based on the first angle, the second angle, and the third angle.

2. The method as defined in claim 1 , wherein the first tangent line represents a first linear tangent function and the second tangent line represents a second linear tangent function.

3. The method as defined in claim 1 , wherein fitting the curve to at least the subset of the frequency bands includes performing least squares error analysis to obtain coefficients for the signature function to fit at least the subset of the frequency bands.

4. The method as defined in claim 1 , wherein creating the signature values includes averaging the first angle, the second angle, and the third angle.

5. The method as defined in claim 1 , further including generating a signature for media represented by the block of signal samples, by:
calculating signature values for additional blocks of signal samples representing the media; and
generating the signature for the media as an ordered set of the signature values for the blocks of signal samples.

6. The method as defined in claim 5 , further including transmitting the signature to an audience measurement entity.

7. The method as defined in claim 5 , wherein generating the signature further includes calculating a mean value of the signature values, and calculating the signature values includes determining a signature bit by comparing a mean angle of the first angle, the second angle, and the third angle to the mean value.

8. The method as defined in claim 1 , wherein calculating the signature values further includes:
selecting the first index value;
calculating the second index value based on a first value of the signature function at the first index value and a derivative of the signature function at the first index value, the second tangent line being determined based on the second index value; and
calculating the third index value based on a second value of the signature function at the second index value and the derivative of the signature function at the second index value, the third tangent line being determined based on the third index value.

9. The method as defined in claim 1 , wherein transforming the block of signal samples includes:
applying a polyphase quadrature filter bank to the block of signal samples to obtain frequency bands; and
applying a modified discrete cosine transform to perform energy compaction on the frequency bands to generate the frequency-domain representation.

10. The method as defined in claim 1 , further including selecting the subset of the frequency bands in the frequency-domain representation to include a set of adjacent ones of the frequency bands that have at least a threshold percentage of a total energy in the frequency-domain representation.

11. An apparatus, comprising:
a transformer to transform a block of signal samples from a time-domain representation to a frequency-domain representation including multiple frequency bands;
a curve fitter to determining a signature function by fitting a curve to at least a subset of the frequency bands;
an angle calculator to:
calculate a first angle between a reference line and a first tangent line that is tangent to the signature function at a first index value in a set of index values over which the signature function is defined;
calculate a second angle between the reference line and a second tangent line that is tangent to the signature function at a second index value in the set of index values; and
calculate a third angle between the reference line and a third tangent line that is tangent to the signature function at a third index value in the set of index values; and

a tuple generator to generate signature values based on the first angle, the second angle, and the third angle.

12. The apparatus as defined in claim 11 , further including a transducer to generate a signal and a sampler to generate the block of signal samples from the signal.

13. The apparatus as defined in claim 11 , wherein the first tangent line represents a first linear tangent function, and the second tangent line represents a second linear tangent function.

14. The apparatus as defined in claim 11 , further including:
a polyphase quadrature filter bank to transform the block of signal samples to obtain frequency bands; and
an energy compactor to perform energy compaction by applying a modified discrete cosine transform on the frequency bands to generate the frequency-domain representation.

15. The apparatus as defined in claim 11 , further including an index selector to:
select the first index value;
calculate the second index value based on a first value of the signature function at the first index value and a derivative of the signature function at the first index value, the angle calculator to determine the second tangent line based on the second index value; and
calculate the third index value based on a second value of the signature function at the second index value and the derivative of the signature function at the second index value, the angle calculator to determine the third tangent line based on the third index value.

16. The apparatus as defined in claim 11 , further including a signature generator to generate a signature for media represented by the block of signal samples, by:
calculating signature values for additional blocks of signal samples representing the media; and
generating the signature for the media as an ordered set of the signature values for the blocks of signal samples.

17. The apparatus as defined in claim 16 , wherein the tuple generator is to calculate signature values for additional blocks of samples, the block of signal samples representing the media, and the signature generator is to generate the signature for the media as an ordered set of the signature values.

18. The apparatus as defined in claim 16 , wherein the signature generator is to calculate a mean value of the signature values, and is to calculate the signature values by comparing a mean angle of the first angle, the second angle, and the third angle to the mean value to determine a signature bit.

19. A tangible computer readable storage medium comprising computer readable instructions which, when executed, cause a logic circuit to at least:
transform a block of signal samples from a time-domain representation to a frequency-domain representation including multiple frequency bands;
determine a signature function by fitting a curve to at least a subset of the frequency bands; and
calculate signature values for the block of signal samples by:
calculating a first angle between a refe

Assignees

• Nielsen Co Us Llc

Inventors

• Kariyappa Manjunath Puttappa
• Edara Srinivasa Rao
• Kalayil Suresh Kumar Kulathumkal

Classifications

• G11B20/10527

  Audio or video recording; Data buffering arrangements (G11B20/12 - G11B20/18 take precedence) · CPC title

• G06F16/683 Primary

  using metadata automatically derived from the content · CPC title

• H04H2201/90

  characterised by the use of signatures · CPC title

• G06F3/165

  Management of the audio stream, e.g. setting of volume, audio stream path · CPC title

• H04H60/37

  for identifying segments of broadcast information, e.g. scenes or extracting programme ID · CPC title