Methods and apparatus to identify sources of network streaming services using windowed sliding transforms

1. An apparatus comprising:

a windowed sliding transformer to:

perform a first time-frequency analysis of a first block of a received first audio signal according to a first trial compression configuration; and

perform a second time-frequency analysis of the first block of the received first audio signal according to a second trial compression configuration, the windowed sliding transformer including a multiplier to multiply a vector including a first frequency-domain representation and a matrix including a second frequency-domain representation;

a coding format identifier to identify, from the received first audio signal representing a decompressed second audio signal, an audio compression configuration used to compress a third audio signal to form the decompressed second audio signal, the audio compression configuration including one of the first trial compression configuration or the second trial compression configuration; and

a source identifier to identify a source of the decompressed second audio signal based on the identified audio compression configuration.

2. The apparatus of claim 1 , further including:

an artifact computer to:

determine a first compression artifact resulting from the first time-frequency analysis; and

determine a second compression artifact resulting from the second time-frequency analysis; and

a controller to select one of the first trial compression configuration or the second trial compression configuration as the audio compression configuration based on the first compression artifact and the second compression artifact.

3. The apparatus of claim 2 , wherein to select the one of the first trial compression configuration or the second trial compression configuration based on the first compression artifact and the second compression artifact, the controller is to compare includes comparing the first compression artifact and the second compression artifact.

4. The apparatus of claim 2 , wherein:

the windowed sliding transformer is to:

perform a third time-frequency analysis of a second block of the received first audio signal according to the first trial compression configuration; and

perform a fourth time-frequency analysis of the second block of the received first audio signal according to the second trial compression configuration;

the artifact computer is to:

determine a third compression artifact resulting from the third time-frequency analysis; and

determine a fourth compression artifact resulting from the fourth time-frequency analysis; and

the controller is to select the one of the first trial compression configuration or the second trial compression configuration as the audio compression configuration based on the first compression artifact, the second compression artifact, the third compression artifact, and the fourth compression artifact.

5. The apparatus of claim 4 , further including:

a post processor to:

combine the first compression artifact and the third compression artifact to form a first score; and

combine the second compression artifact and the fourth compression artifact to form a second score; and

wherein to select the one of the first trial compression configuration or the second trial compression configuration as the audio compression configuration, the controller is to compare the first score and the second score.

6. The apparatus of claim 5 , wherein to combine the first compression artifact and the third compression artifact to form the first score, the post processor is to:

map the first compression artifact and a first offset associated with the first compression artifact to a first polar coordinate;

map the third compression artifact and a second offset associated with the second compression artifact to a second polar coordinate; and

compute the first score as a circular mean of the first polar coordinate and the second polar coordinate.

7. The apparatus of claim 1 , wherein the first block of the received first audio signal includes first time-domain samples, and the windowed sliding transformer includes:

a transformer to transform the first a first block of time-domain samples into the first frequency-domain representation based on a third frequency-domain representation of a third block of the received first audio signal, the third block of the received first audio signal including second time-domain samples; and

a windower to apply the second frequency-domain representation to the first frequency-domain representation, the second frequency-domain representation representative of a time-domain window function.

8. The apparatus of claim 7 , wherein the windower includes the multiplier and the matrix.

9. The apparatus of claim 7 , further including a kernel generator to compute a transform of the time-domain window function to compute the matrix.

10. The apparatus of claim 9 , wherein the kernel generator is to set a value of a cell of the matrix to zero based on a comparison of the value and a threshold.

11. A method comprising:

performing a first time-frequency analysis of a first block of a received first audio signal according to a first trial compression configuration;

performing a second time-frequency analysis of the first block of the received first audio signal according to a second trial compression configuration;

multiplying a vector including a first frequency-domain representation and a matrix including a second frequency-domain representation;

identifying, from the received first audio signal representing a decompressed second audio signal, an audio compression configuration used to compress a third audio signal to form the decompressed second audio signal, the audio compression configuration including one of the first trial compression configuration or the second trial compression configuration; and

identifying a source of the decompressed second audio signal based on the identified audio compression configuration.

12. The method of claim 11 , wherein identifying the source of the decompressed second audio signal based on the identified audio compression configuration includes:

identifying a coding format based on the identified audio compression configuration; and

identifying the source based on the coding format.

13. The method of claim 11 , wherein the first block of the received first audio signal includes first time-domain samples, and applying the method further includes:

transforming the first time-domain samples of an input signal into the first frequency-domain representation based on a third frequency-domain representation of a third block of the received first audio signal, the third block of the received first audio signal including second time-domain samples; and

applying the second frequency-domain representation to the first frequency-domain representation, the second frequency-domain representation representative of a time-domain window function.

14. The method of claim 13 , wherein applying the second frequency-domain representation to the first frequency-domain representation includes multiplying the vector and the matrix.

15. The method of claim 13 , further including transforming the time-domain window function to the second frequency-domain representation.

16. The method of claim 15 , wherein transforming the first time-domain samples into the first frequency-domain representation includes computing a sliding discrete Fourier transform.

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

perform a first time-frequency analysis of a first block of a received first audio signal according to a first trial compression configuration;

perform a second time-frequency analysis of the first block of the first received audio signal according to a second trial compression configuration;

multiply a vector including a first frequency-domain representation and a matrix including a second frequency-domain representation;

identify, from the received first audio signal representing a decompressed second audio signal, an audio compression configuration used to compress a third audio signal to form the decompressed second audio signal, the audio compression configuration including one of the first trial compression configuration or the second trial compression configuration; and

identify a source of the decompressed second audio signal based on the identified audio compression configuration.

18. The non-transitory computer-readable medium of claim 17 , wherein to identify the source of the decompressed second audio signal based on the identified audio compression configuration, the instructions, when executed, cause the machine to:

identify a coding format based on the identified audio compression configuration; and

identify the source based on the coding format.

19. The non-transitory computer-readable medium of claim 17 , wherein the first block of the received first audio signal includes first time-domain samples, and the instructions, when executed, cause the machine to:

transform the first time-domain samples into the first frequency-domain representation based on a third frequency-domain representation of a third block of the received first audio signal, the third block of the received first audio signal including second time-domain samples; and

apply the second frequency-domain representation to the first frequency-domain representation, the second frequency-domain representation representative of a time-domain window function.

20. The non-transitory computer-readable medium of claim 19 , wherein to transform the first time-domain samples into the first frequency-domain representation, the instructions, when executed, cause the machine to compute a sliding discrete Fourier transform.

21. An apparatus comprising:

means for performing time-frequency analyses to:

perform a first time-frequency analysis of a first block of a received first audio signal according to a first trial compression configuration; and

perform a second time-frequency analysis of the first block of the received first audio signal according to a second trial compression configuration;

means for multiplying a vector including a first frequency-domain representation and a matrix including a second frequency-domain representation;

first means for identifying, from the received first audio signal representing a decompressed second audio signal, an audio compression configuration used to compress a third audio signal to form the decompressed second audio signal;

second means for identifying a source of the decompressed second audio signal based on an identified audio compression configuration;

means for determining compression artifacts to:

determine a first compression artifact resulting from the first time-frequency analysis; and

determine a second compression artifact resulting from the second time-frequency analysis; and

means for selecting one of the first trial compression configuration or the second trial compression configuration as the audio compression configuration based on the first compression artifact and the second compression artifact.

22. The apparatus of claim 21 , wherein the first block of the received first audio signal includes first time-domain samples, and the apparatus further includes:

means for transforming the first time-domain samples into the first frequency-domain representation based on a third frequency-domain representation of a third block of the received first audio signal, the third block of the received first audio signal including second time-domain samples; and

means for applying the second frequency-domain representation to the first frequency-domain representation, the second frequency-domain representation representative of a time-domain window function.

23. The apparatus of claim 22 , wherein the means for transforming is further to transform the first time-domain samples into the first frequency-domain representation by computing a sliding discrete Fourier transform.

24. An apparatus comprising:

memory;

instructions; and

processor circuitry to execute the instructions to:

perform a first time-frequency analysis of a first block of a received first audio signal according to a first trial compression configuration;

perform a second time-frequency analysis of the first block of the received first audio signal according to a second trial compression configuration;

multiply a vector including a first frequency-domain representation and a matrix including a second frequency-domain representation;

identify, from the received first audio signal representing a decompressed second audio signal, an audio compression configuration used to compress a third audio signal to form the decompressed second audio signal, the audio compression configuration including one of the first trial compression configuration or the second trial compression configuration; and

identify a source of the decompressed second audio signal based on the identified audio compression configuration.

25. The apparatus of claim 24 , wherein the processor circuitry is to execute the instructions to:

determine a first compression artifact resulting from the first time-frequency analysis;

determine a second compression artifact resulting from the second time-frequency analysis; and

select one of the first trial compression configuration or the second trial compression configuration as the audio compression configuration based on the first compression artifact and the second compression artifact.

26. The apparatus of claim 25 , wherein to select the one of the first trial compression configuration or the second trial compression configuration based on the first compression artifact and the second compression artifact, the processor circuitry is to execute the instructions to compare the first compression artifact and the second compression artifact.

27. The apparatus of claim 25 , wherein the processor circuitry is to execute the instructions to:

perform a third time-frequency analysis of a second block of the received first audio signal according to the first trial compression configuration;

perform a fourth time-frequency analysis of the second block of the received first audio signal according to the second trial compression configuration;

determine a third compression artifact resulting from the third time-frequency analysis; and

determine a fourth compression artifact resulting from the fourth time-frequency analysis; and

select the one of the first trial compression configuration or the second trial compression configuration as the audio compression configuration based on the first compression artifact, the second compression artifact, the third compression artifact, and the fourth compression artifact.

28. The apparatus of claim 27 , wherein the processor circuitry is to execute the instructions to:

combine the first compression artifact and the third compression artifact to form a first score;

combine the second compression artifact and the fourth compression artifact to form a second score; and

compare the first score and the second score to select the one of the first trial compression configuration or the second trial compression configuration as the audio compression configuration.

29. The apparatus of claim 28 , wherein to combine the first compression artifact and the third compression artifact to form the first score the processor circuitry is to execute the instructions to:

map the first compression artifact and a first offset associated with the first compression artifact to a first polar coordinate;

map the third compression artifact and a second offset associated with the second compression artifact to a second polar coordinate; and

compute the first score as a circular mean of the first polar coordinate and the second polar coordinate.

30. The apparatus of claim 24 , wherein the first block of the received first audio signal includes first time-domain samples, and the processor circuitry is to execute the instructions to:

transform the first time-domain samples into the first frequency-domain representation based on a third frequency-domain representation of a third block of the received first audio signal, the third block of the received first audio signal including second time-domain samples; and

apply the second frequency-domain representation to the first frequency-domain representation, the second frequency-domain representation representative of a time-domain window function.

31. The apparatus of claim 30 , wherein to compute the matrix, the processor circuitry is to execute the instructions to compute a transform of the time-domain window function.

32. The apparatus of claim 31 , wherein the processor circuitry is to execute the instructions to set a value of a cell of the matrix to zero based on a comparison of the value and a threshold.