Patent Publication Number: US-11651776-B2

Title: Methods, apparatus and articles of manufacture to identify sources of network streaming services

Description:
RELATED APPLICATION 
     This patent claims the priority benefit of U.S. patent application Ser. No. 15/793,543, which was filed on Oct. 25, 2017. U.S. patent application Ser. No. 15/793,543 is hereby incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE DISCLOSURE 
     This disclosure relates generally to network streaming services, and, more particularly, to methods, apparatus and articles of manufacture to identify sources of network streaming services. 
     BACKGROUND 
     Audience measurement entities (AMEs) perform, for example, audience measurement, audience categorization, measurement of advertisement impressions, measurement of media exposure, etc., and link such measurement information with demographic information. AMEs can determine audience engagement levels for media based on registered panel members. That is, an AME enrolls people who consent to being monitored into a panel. The AME then monitors those panel members to determine media (e.g., television programs or radio programs, movies, DVDs, advertisements (ads), websites, etc.) exposed to those panel members. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    illustrates an example environment in which an example AME, in accordance with this disclosure, identifies sources of network streaming services. 
         FIG.  2    is a block diagram illustrating an example implementation of the example coding format identifier of  FIG.  1   . 
         FIG.  3    is a diagram illustrating an example operation of the example coding format identifier of  FIG.  2   . 
         FIG.  4    is an example polar graph of example scores and offsets. 
         FIG.  5    is a flowchart representing example processes that may be implemented as machine-readable instructions that may be executed to implement the example AME to identify sources of network streaming services. 
         FIG.  6    is a flowchart representing another example processes that may be implemented as machine-readable instructions that may be executed to implement the example coding format identifier of  FIGS.  1  and/or  2    to identify sources of network streaming services. 
         FIG.  7    illustrates an example processor platform structured to execute the example machine-readable instructions of  FIG.  6    to implement the example coding format identifier of  FIGS.  1  and/or  2   . 
     
    
    
     Wherever possible, the same reference numbers will be used throughout the drawing(s) and accompanying written description to refer to the same or like parts. Connecting lines or connectors shown in the various figures presented are intended to represent example functional relationships and/or physical or logical couplings between the various elements. 
     DETAILED DESCRIPTION 
     AMEs typically identify the source of media (e.g., television programs or radio programs, movies, DVDs, advertisements (ads), websites, etc.) when measuring exposure to the media. In some examples, media has imperceptible audience measurement codes embedded therein (e.g., in an audio signal portion) that allow the media and a source of the media to be determined. However, media delivered via a network streaming service (e.g., NETFLIX®, HULU®, YOUTUBE®, AMAZON PRIME®, APPLE TV®, etc.) may not include audience measurement codes, rendering identification of the media source difficult, to determine the source of media. 
     It has been advantageously discovered that, in some instances, different sources of streaming media (e.g., NETFLIX®, HULU®, YOUTUBE®, AMAZON PRIME®, APPLE TV®, etc.) use different audio compression configurations to store and stream the media they host. In some examples, an audio compression configuration is a set of one or more parameters that define, among possibly other things, an audio coding format (e.g., MP1, MP2, MP3, AAC, AC-3, Vorbis, WMA, DTS, etc.), compression parameters, framing parameters, etc. Because different sources use different audio compression, the sources can be distinguished (e.g., identified, detected, determined, etc.) based on the audio compression applied to the media. The media is de-compressed during playback. In some examples, the de-compressed audio signal is compressed using different trial audio compression configurations for compression artifacts. Because compression artifacts become detectable (e.g., perceptible, identifiable, distinct, etc.) when a particular audio compression configuration matches the compression used during the original encoding, the presence of compression artifacts can be used to identify one of the trial audio compression configurations as the audio compression configuration used originally. After the compression configuration is identified, the AME can infer the original source of the audio. Example compression artifacts are discontinuities between points in a spectrogram, a plurality of points in a spectrogram that are small (e.g., below a threshold, relative to other points in the spectrogram), one or more values in a spectrogram having probabilities of occurrence that are disproportionate compared to other values (e.g., a large number of small values), etc. In instances where two or more sources use the same audio compression configuration and are associated with compression artifacts, the audio compression configuration may be used to reduce the number of sources to consider. Other methods may then be used to distinguish between the sources. However, for simplicity of explanation the examples disclosed herein assume that sources are associated with different audio compression configurations. 
     Disclosed examples identify the source(s) of media by identifying the audio compression applied to the media (e.g., to an audio portion of the media). In some examples, audio compression identification includes the identification of the compression that an audio signal has undergone, regardless of the content. Compression identification can include, for example, identification of the bit rate at which the audio data was encoded, the parameters used at the time-frequency decomposition stage, the samples in the audio signal where the framing took place before the windowing and transform were applied, etc. As disclosed herein, the audio compression can be identified from media that has been de-compressed and output using an audio device such as a speaker, and recorded. The recorded audio, which has undergone lossy compression and de-compression, can be re-compressed according to different trial audio compressions. In some examples, the trial re-compression that results in the largest compression artifacts is identified as the audio compression that was used to originally compress the media. The identified audio compression is used to identify the source of the media. While the examples disclosed herein only partially re-compress the audio (e.g., perform only the time-frequency analysis stage of compression), full re-compression may be performed. 
     Reference will now be made in detail to non-limiting examples of this disclosure, examples of which are illustrated in the accompanying drawings. The examples are described below by referring to the drawings. 
       FIG.  1    illustrates an example environment  100  in which an example AME  102 , in accordance with this disclosure, identifies sources of network streaming services. To provide media  104  (e.g., a song, a movie  105  including video  109  and audio  110 , a television show, a game, etc.), the example environment  100  includes one or more streaming media sources (e.g., NETFLIX®, HULU®, YOUTUBE®, AMAZON PRIME®, APPLE TV®, etc.), an example of which is designated at reference numeral  106 . To form compressed audio signals (e.g., the audio  110  of the video program  105 ) from an audio signal  111 , the example media source  106  includes an example audio compressor  112 . In some examples, audio is compressed by the audio compressor  112  (or another compressor implemented elsewhere) and stored in the media data store  108  for subsequent recall and streaming. The audio signals may be compressed by the example audio compressor  112  using any number and/or type(s) of audio compression configurations (e.g., audio coding formats (e.g., MP1, MP2, MP3, AAC, AC-3, Vorbis, WMA, DTS, etc.), compression parameters, framing parameters, etc.) Media may be stored in the example media data store  108  using any number and/or type(s) of data structure(s). The media data store  108  may be implemented using any number and/or type(s) of non-volatile, and/or volatile computer-readable storage device(s) and/or storage disk(s). 
     To present (e.g., playback, output, display, etc.) media, the example environment  100  of  FIG.  1    includes any number and/or type(s) of example media presentation device, one of which is designated at reference numeral  114 . Example media presentation devices  114  include, but are not limited to a gaming console, a personal computer, a laptop computer, a tablet, a smart phone, a television, a set-top box, or, more generally, any device capable of presenting media. The example media source  106  provides the media  104  (e.g., the movie  105  including the compressed audio  110 ) to the example media presentation device  114  using any number and/or type(s) of example public, and/or public network(s)  116  or, more generally, any number and/or type(s) of communicative couplings. 
     To present (e.g., playback, output, etc.) audio (e.g., a song, an audio portion of a video, etc.), the example media presentation device  114  includes an example audio de-compressor  118 , and an example audio output device  120 . The example audio de-compressor  118  de-compresses the audio  110  to form de-compressed audio  122 . In some examples, the audio compressor  112  specifies to the audio de-compressor  118  in the compressed audio  110  the audio compression configuration used by the audio compressor  112  to compress the audio. The de-compressed audio  122  is output by the example audio output device  120  as an audible signal  124 . Example audio output devices  120  include, but are not limited, a speaker, an audio amplifier, headphones, etc. While not shown, the example media presentation device  114  may include additional output devices, ports, etc. that can present signals such as video signals. For example, a television includes a display panel, a set-top box includes video output ports, etc. 
     To record the audible audio signal  124 , the example environment  100  of  FIG.  1    includes an example recorder  126 . The example recorder  126  of  FIG.  1    is any type of device capable of capturing, storing, and conveying the audible audio signal  124 . In some examples, the recorder  126  is implemented by a people meter owned and operated by The Nielsen Company, the Applicant of the instant application. In some examples, the media presentation device  114  is a device (e.g., a personal computer, a laptop, etc.) that can output the audio  124  and record the audio  124  with a connected or integral microphone. In some examples, the de-compressed audio  122  is recorded without being output. Audio signals  128  recorded by the example audio recorder  126  are conveyed to the example AME  102  for analysis. 
     To identify the media source  106  associated with the audible audio signal  124 , the example AME  102  includes an example coding format identifier  130  and an example source identifier  132 . The example coding format identifier  130  identifies the audio compression applied by the audio compressor  112  to form the compressed audio signal  110 . The coding format identifier  130  identifies the audio compression from the de-compressed audio signal  124  output by the audio output device  120 , and recorded by the audio recorder  126 . The recorded audio  128 , which has undergone lossy compression at the audio compressor  112 , and de-compression at the audio de-compressor  118  is re-compressed by the coding format identifier  130  according to different trial audio compression types and/or settings. In some examples, the trial re-compression that results in the largest compression artifacts is identified by the coding format identifier  130  as the audio compression that was used at the audio compressor  112  to originally compress the media. 
     The example source identifier  130  of  FIG.  1    uses the identified audio compression to identify the source  106  of the media  104 . In some examples, the source identifier  130  uses a lookup table to identify, or narrow the search space for identifying the media source  106  associated with an audio compression identified by the coding format identifier  130 . An association of the media  104  and the media source  106 , among other data (e.g., time, day, viewer, location, etc.) is recorded in an example exposure database  134  for subsequent development of audience measurement statistics. 
       FIG.  2    is a block diagram illustrating an example implementation of the example coding format identifier  130  of  FIG.  1   .  FIG.  3    is a diagram illustrating an example operation of the example coding format identifier  130  of  FIG.  2   . For ease of understanding, it is suggested that the interested reader refer to  FIG.  3    together with  FIG.  2   . Wherever possible, the same reference numbers are used in  FIGS.  2  and  3   , and the accompanying written description to refer to the same or like parts. 
     To store (e.g., buffer, hold, etc.) incoming samples of the recorded audio  128 , the example coding format identifier  130  includes an example buffer  202 . The example buffer  202  of  FIG.  2    may be implemented using any number and/or type(s) of non-volatile, and/or volatile computer-readable storage device(s) and/or storage disk(s). 
     To perform time-frequency analysis, the example coding format identifier  130  includes an example time-frequency analyzer  204 . The example time-frequency analyzer  204  of  FIG.  2    windows the recorded audio  128  into windows (e.g., segments of the buffer  202  defined by a sliding or moving window), and estimates the spectral content of the recorded audio  128  in each window. 
     To obtain portions of the example buffer  202 , the example coding format identifier  130  includes an example windower  206 . The example windower  206  of  FIG.  2    is configurable to obtain from the buffer  202  windows S 1:L , S 2:L+1 , . . . S N/2+1:L+N/2  (e.g., segments, portions, etc.) of L samples of the recorded audio  128  to be processed. The example windower  206  obtains a specified number of samples starting with a specified starting offset 1, 2, . . . N/2+1 in the buffer  202 . The windower  206  can be configured to apply a windowing function to the obtained windows S 1:L , S 2:L+1 , . . . S N/2+1:L+N/2  of samples to reduce spectral leakage. Any number and/or type(s) of window functions may be implemented including, for example, a rectangular window, a sine window, a slope window, a Kaiser-Bessel derived window, etc. 
     To convert the samples obtained and windowed by the windower  206  to a spectrogram (three of which are designated at reference numeral  304 ,  305  and  306 ), the example coding format identifier  130  of  FIG.  2    includes an example transformer  210 . Any number and/or type(s) of transforms may be computed by the transformer  210  including, but not limited to, a polyphase quadrature filter (PQF), a modified discrete cosine transform (MDCT), hybrids thereof, etc. The example transformer  210  transforms each window S 1:L , S 2:L+1 , . . . S N/2+1:L+N/2  into a corresponding spectrogram  304 ,  305 , . . .  306 . 
     To compute compression artifacts, the example coding format identifier  130  of  FIG.  2    includes an example artifact computer  212 . The example artifact computer  212  of  FIG.  2    detects small values (e.g., values that have been quantized to zero) in the spectrograms  304 - 306 . Small values in the spectrograms  304 - 306  represent compression artifacts, and are used, in some examples, to determine when a trial audio compression corresponds to the audio compression applied by the audio compressor  112  ( FIG.  1   ). 
     To compute an average of the values of a spectrogram  304 - 306 , the artifact computer  212  of  FIG.  2    includes an example averager  214 . The example averager  214  of  FIG.  2    computes an average A 1 , A 2 , . . . A N/2+1  of the values of corresponding spectrograms  304 - 306  for the plurality of windows S 1:L , S 2:L+1 , . . . S N/2+1:L+N/2  of the block of samples  202 . The averager  214  can compute various means, such as, an arithmetic mean, a geometric mean, etc. Assuming the audio content stays approximately the same between two adjacent spectrograms  304 ,  305 , . . .  306 , the averages A 1 , A 2 , . . . A N/2+1  will also be similar. However, when audio compression configuration and framing match those used at the audio compressor  112 , small values will appear in a particular spectrogram  304 - 306 , and differences D 1 , D 2 , . . . D N/2  between the averages A 1 , A 2 , . . . A N/2+1  will occur. The presence of these small values in a spectrogram  304 - 306  and/or differences D 1 , D 2 , . . . D N/2  between averages A 1 , A 2 , . . . A N/2+1  can be used, in some examples, to identify when a trial audio compression configuration results in compression artifacts. 
     To detect the small values, the example artifact computer  212  includes an example differencer  216 . The example differencer  216  of  FIG.  2    computes the differences D 1 , D 2 , . . . D N/2  (see  FIG.  3   ) between averages A 1 , A 2 , . . . A N/2+1  of the spectrograms  304 - 306  computed using different window locations 1, 2, . . . N/2+1. When a spectrogram  304 - 306  has small values representing potential compression artifacts, it will have a smaller spectrogram average A 1 , A 2 , . . . A N/2+1  than the spectrograms  304 - 306  for other window locations. Thus, its differences D 1 , D 2 , . . . D N/2  from the spectrograms  304 - 306  for the other window locations will be larger than differences D 1 , D 2 , . . . D N/2  between other pairs of spectrograms  304 - 306 . In some examples, the differencer  216  computes absolute (e.g., positive valued) differences. 
     To identify the largest difference D 1 , D 2 , . . . D N/2  between the averages A 1 , A 2 , . . . A N/2+1  of spectrograms  304 - 306 , the example artifact computer  212  of  FIG.  2    includes an example peak identifier  218 . The example peak identifier  218  of  FIG.  2    identifies the largest difference D 1 , D 2 , . . . D N/2  for a plurality of window locations 1, 2, . . . N/2+1. The largest difference D 1 , D 2 , . . . D N/2  corresponding to the window location 1, 2, ... N/2+1 used by the audio compressor  112 . As shown in the example of  FIG.  3   , the peak identifier  218  identifies the difference D 1 , D 2 , . . . D N/2  having the largest value. As will be explained below, in some examples, the largest value is considered a confidence score  308  (e.g., the greater its value the greater the confidence that a compression artifact was found), and is associated with an offset  310  (e.g., 1, 2, . . . , N/2+1) that represents the location of the window S 1:L , S 2:L+1 , . . . S N/2+1:L+N/2  associated with the average A 1 , A 2 , . . . A N/2+1 . The example peak identifier  218  stores the confidence score  308  and the offset  310  in a coding format scores data store  220 . The confidence score  308  and the offset  310  may be stored in the example coding format scores data store  220  using any number and/or type(s) of data structure(s). The coding format scores data store  220  may be implemented using any number and/or type(s) of non-volatile, and/or volatile computer-readable storage device(s) and/or storage disk(s). 
     A peak in the differences D 1 , D 2 , . . . D N/2  nominally occurs every T samples in the signal. In some examples, T is the hop size of the time-frequency analysis stage of a coding format, which is typically half of the window length L. In some examples, confidence scores  308  and offsets  310  from multiple blocks of samples of a longer audio recording are combined to increase the accuracy of coding format identification. In some examples, blocks with scores under a chosen threshold are ignored. In some examples, the threshold can be a statistic computed from the differences, for example, the maximum divided by the mean. In some examples, the differences can also be first normalized, for example, by using the standard score. To combine confidence scores  308  and offsets  310 , the example coding format identifier  130  includes an example post processor  222 . The example post processor  222  of  FIG.  2    translates pairs of confidence scores  308  and offsets  310  into polar coordinates. In some examples, a confidence score  308  is translated into a radius (e.g., expressed in decibels), and an offset  310  is mapped to an angle (e.g., expressed in radians modulo its periodicity). In some examples, the example post processor  222  computes a circular mean of these polar coordinate points (i.e., a mean computed over a circular region about an origin), and obtains an average polar coordinate point whose radius corresponds to an overall confidence score  224 . In some examples, a circular sum can be computed, by multiplying the circular mean by the number of blocks whose scores was above the chosen threshold. The closer the pairs of points are to each other in the circle, and the further they are from the center, the larger the overall confidence score  224 . In some examples, the post processor  222  computes a circular sum by multiplying the circular mean and the number of blocks whose scores were above the chosen threshold. The example post processor  222  stores the overall confidence score  224  in the coding format scores data store  220  using any number and/or type(s) of data structure(s). An example polar plot  400  of example pairs of scores and offsets is shown in  FIG.  4   , for five different audio compression configurations: MP3, AAC, AC-3, Vorbis and WMA. As shown in  FIG.  4   , the AC-3 coding format has a plurality of points (e.g., see the example points in the example region  402 ) having similar angles (e.g., similar window offsets), and larger scores (e.g., greater radiuses) than the other coding formats. If a circular mean is computed for each configuration, the means for MP3, AAC, Vorbis and WMA would be near the origin, while the mean for AC-3 would be distinct from the origin, indicating that the audio  128  was originally compressed with the AC-3 coding format. 
     To store sets of audio compression configurations, the example coding format identifier  130  of  FIG.  2    includes an example compression configurations data store  226 . To control coding format identification, the example coding format identifier  130  of  FIG.  2    includes an example controller  228 . To identify the audio compression applied to the audio  128 , the example controller  228  configures the time-frequency analyzer  204  with different compression configurations. For combinations of a trial compression configuration (e.g., AC-3) and each of a plurality of window offsets, the time-frequency analyzer  204  computes a spectrogram  304 - 306 . The example artifact computer  212  and the example post processor  222  determine the overall confidence score  224  for each the trial compression configuration. The example controller  228  identifies (e.g., selects) the one of the trial compression configurations having the largest overall confidence score  224  as the compression configuration that had been applied to the audio  128 . 
     The compression configurations may be stored in the example compression configurations data store  226  using any number and/or type(s) of data structure(s). The compression configurations data store  226  may be implemented using any number and/or type(s) of non-volatile, and/or volatile computer-readable storage device(s) and/or storage disk(s). The example controller  228  of  FIG.  2    may be implemented using, for example, one or more of each of a circuit, a logic circuit, a programmable processor, a programmable controller, a graphics processing unit (GPU), a digital signal processor (DSP), an application specific integrated circuit (ASIC), a programmable logic device (PLD), a field programmable gate array (FPGA), and/or a field programmable logic device (FPLD). 
     While an example implementation of the coding format identifier  130  is shown in  FIG.  2   , other implementations, such as machine learning, etc. may additionally, and/or alternatively, be used. While an example manner of implementing the coding format identifier  130  of  FIG.  1    is illustrated in  FIG.  2   , one or more of the elements, processes and/or devices illustrated in  FIG.  2    may be combined, divided, re-arranged, omitted, eliminated and/or implemented in any other way. Further, the example time-frequency analyzer  204 , the example windower  206 , the example transformer  210 , the example artifact computer  212 , the example averager  214 , the example differencer  216 , the example peak identifier  218 , the example post processor  222 , the example controller  228  and/or, more generally, the example coding format identifier  130  of  FIG.  2    may be implemented by hardware, software, firmware and/or any combination of hardware, software and/or firmware. Thus, for example, any of the example time-frequency analyzer  204 , the example windower  206 , the example transformer  210 , the example artifact computer  212 , the example averager  214 , the example differencer  216 , the example peak identifier  218 , the example post processor  222 , the example controller  228  and/or, more generally, the example coding format identifier  130  could be implemented by one or more analog or digital circuit(s), logic circuits, programmable processor(s), programmable controller(s), GPU(s), DSP(s), ASIC(s), PLD(s), FPGA(s), and/or FPLD(s). When reading any of the apparatus or system claims of this patent to cover a purely software and/or firmware implementation, at least one of the example, time-frequency analyzer  204 , the example windower  206 , the example transformer  210 , the example artifact computer  212 , the example averager  214 , the example differencer  216 , the example peak identifier  218 , the example post processor  222 , the example controller  228 , and/or the example coding format identifier  130  is/are hereby expressly defined to include a non-transitory computer-readable storage device or storage disk such as a memory, a digital versatile disk (DVD), a compact disk (CD), a Blu-ray disk, etc. including the software and/or firmware. Further still, the example coding format identifier  130  of  FIG.  1    may include one or more elements, processes and/or devices in addition to, or instead of, those illustrated in  FIG.  2   , and/or may include more than one of any or all the illustrated elements, processes and devices. 
     A flowchart representative of example machine-readable instructions for implementing the example AME  102  of  FIG.  1    is shown in  FIG.  5   . In this example, the machine-readable instructions comprise a program for execution by a processor such as the processor  710  shown in the example processor platform  700  discussed below in connection with  FIG.  7   . The program may be embodied in software stored on a non-transitory computer-readable storage medium such as a CD, a floppy disk, a hard drive, a DVD, a Blu-ray disk, or a memory associated with the processor  710 , but the entire program and/or parts thereof could alternatively be executed by a device other than the processor  710  and/or embodied in firmware or dedicated hardware. Further, although the example program is described with reference to the flowchart illustrated in  FIG.  5   , many other methods of implementing the example AME  102  may alternatively be used. For example, the order of execution of the blocks may be changed, and/or some of the blocks described may be changed, eliminated, or combined. Additionally, and/or alternatively, any or all the blocks may be implemented by one or more hardware circuits (e.g., discrete and/or integrated analog and/or digital circuitry, FPGA(s), ASIC(s), comparator(s), operational-amplifier(s) (op-amp(s)), logic circuit(s), etc.) structured to perform the corresponding operation without executing software or firmware. 
     The example program of  FIG.  5    begins at block  502 , where the AME  102  receives a first audio signal (e.g., the example audio signal  128 ) that represents a decompressed a second audio signal (e.g., the example audio signal  110 ) (block  502 ). The example coding format identifier  130  identifies, from the first audio signal, an audio compression configuration used to compress a third audio signal (e.g., the example audio signal  111 ) to form the second audio signal (block  504 ). The example source identifier  132  identifies a source of the second audio signal based on the identified audio compression configuration (block  506 ). Control exits from the example program of  FIG.  5   . 
     A flowchart representative of example machine-readable instructions for implementing the example coding format identifier  130  of  FIGS.  1  and/or  2    is shown in  FIG.  6   . In this example, the machine-readable instructions comprise a program for execution by a processor such as the processor  710  shown in the example processor platform  700  discussed below in connection with  FIG.  7   . The program may be embodied in software stored on a non-transitory computer-readable storage medium such as a CD, a floppy disk, a hard drive, a DVD, a Blu-ray disk, or a memory associated with the processor  710 , but the entire program and/or parts thereof could alternatively be executed by a device other than the processor  710  and/or embodied in firmware or dedicated hardware. Further, although the example program is described with reference to the flowchart illustrated in  FIG.  6   , many other methods of implementing the example coding format identifier  130  may alternatively be used. For example, the order of execution of the blocks may be changed, and/or some of the blocks described may be changed, eliminated, or combined. Additionally, and/or alternatively, any or all the blocks may be implemented by one or more hardware circuits (e.g., discrete and/or integrated analog and/or digital circuitry, FPGA(s), ASIC(s), comparator(s), operational-amplifier(s) (op-amp(s)), logic circuit(s), etc.) structured to perform the corresponding operation without executing software or firmware. 
     The example program of  FIG.  6    begins at block  602 , where for each set of trial compression configuration, each block  202  of samples (block  603 ), and each window offset M (block  604 ), the example windower  206  creates a window S M:L+M  (block  606 ), and the example transformer  210  computes a spectrogram  304 - 306  of the window S M:L+M  (block  608 ). The average  214  computes an average A M  of the spectrogram  304 - 306  (block  610 ). When the average A M  of a spectrogram  304 - 306  has been computed for each window offset M (block  612 ), the example difference  216  computes differences D 1 , D 2 , . . . D N/2  between the pairs of the averages A M  (block  614 ). The example peak identifier  218  identifies the largest difference (block  616 ), and stores the largest difference as the score  308  and the associated offset M as the offset  310  in the coding format scores data store  220  (block  618 ). 
     When all blocks have been processed (block  620 ), the example post processor  222  translates the score  308  and offset  310  pairs for the currently considered trial coding format parameter set into polar coordinates, and computes a circular mean of the pairs in polar coordinates as an overall confidence score for the currently considered compression configuration (block  622 ). 
     When all trial compression configurations have been processed (block  624 ), the controller  228  identifies the trial compression configuration set with the largest overall confidence score as the audio compression applied by the audio compressor  112  (block  626 ). Control then exits from the example program of  FIG.  6   . 
     As mentioned above, the example processes of  FIGS.  5  and  6    may be implemented using coded instructions (e.g., computer and/or machine-readable instructions) stored on a non-transitory computer and/or machine-readable medium such as a hard disk drive, a flash memory, a read-only memory, a compact disk, a digital versatile disk, a cache, a random-access memory and/or any other storage device or storage disk in which information is stored for any duration (e.g., for extended time periods, permanently, for brief instances, for temporarily buffering, and/or for caching of the information). As used herein, the term non-transitory computer-readable medium is expressly defined to include any type of computer-readable storage device and/or storage disk and to exclude propagating signals and to exclude transmission media. 
       FIG.  7    is a block diagram of an example processor platform  700  capable of executing the instructions of  FIG.  6    to implement the coding format identifier  130  of  FIGS.  1  and/or  2   . The processor platform  700  can be, for example, a server, a personal computer, a workstation, or any other type of computing device. 
     The processor platform  700  of the illustrated example includes a processor  710 . The processor  710  of the illustrated example is hardware. For example, the processor  710  can be implemented by one or more integrated circuits, logic circuits, microprocessors, GPUs, DSPs or controllers from any desired family or manufacturer. The hardware processor may be a semiconductor based (e.g., silicon based) device. In this example, the processor implements the example time-frequency analyzer  204 , the example windower  206 , the example transformer  210 , the example artifact computer  212 , the example averager  214 , the example differencer  216 , the example peak identifier  218 , the example post processor  222 , and the example controller  228 . 
     The processor  710  of the illustrated example includes a local memory  712  (e.g., a cache). The processor  710  of the illustrated example is in communication with a main memory including a volatile memory  714  and a non-volatile memory  716  via a bus  718 . The volatile memory  714  may be implemented by Synchronous Dynamic Random-access Memory (SDRAM), Dynamic Random-access Memory (DRAM), RAMBUS® Dynamic Random-access Memory (RDRAM®) and/or any other type of random-access memory device. The non-volatile memory  716  may be implemented by flash memory and/or any other desired type of memory device. Access to the main memory  714 ,  716  is controlled by a memory controller (not shown). In this example, the local memory  712  and/or the memory  714  implements the buffer  202 . 
     The processor platform  700  of the illustrated example also includes an interface circuit  720 . The interface circuit  720  may be implemented by any type of interface standard, such as an Ethernet interface, a universal serial bus (USB) interface, a Bluetooth® interface, a near field communication (NFC) interface, and/or a peripheral component interface (PCI) express interface. 
     In the illustrated example, one or more input devices  722  are connected to the interface circuit  720 . The input device(s)  722  permit(s) a user to enter data and/or commands into the processor  710 . The input device(s) can be implemented by, for example, an audio sensor, a microphone, a camera (still or video), a keyboard, a button, a mouse, a touchscreen, a track-pad, a trackball, isopoint and/or a voice recognition system. 
     One or more output devices  724  are also connected to the interface circuit  720  of the illustrated example. The output devices  724  can be implemented, for example, by display devices (e.g., a light emitting diode (LED), an organic light emitting diode (OLED), a liquid crystal display (LCD), a cathode ray tube display (CRT), an in-plane switching (IPS) display, a touchscreen, etc.) a tactile output device, a printer, and/or speakers. The interface circuit  720  of the illustrated example, thus, typically includes a graphics driver card, a graphics driver chip and/or a graphics driver processor. 
     The interface circuit  720  of the illustrated example also includes a communication device such as a transmitter, a receiver, a transceiver, a modem, a residential gateway, and/or network interface to facilitate exchange of data with external machines (e.g., computing devices of any kind) via a network  726  (e.g., an Ethernet connection, a digital subscriber line (DSL), a telephone line, a coaxial cable, a cellular telephone system, a Wi-Fi system, etc.). In some examples of a Wi-Fi system, the interface circuit  720  includes a radio frequency (RF) module, antenna(s), amplifiers, filters, modulators, etc. 
     The processor platform  700  of the illustrated example also includes one or more mass storage devices  728  for storing software and/or data. Examples of such mass storage devices  728  include floppy disk drives, hard drive disks, CD drives, Blu-ray disk drives, redundant array of independent disks (RAID) systems, and DVD drives. 
     Coded instructions  732  including the coded instructions of  FIG.  6    may be stored in the mass storage device  728 , in the volatile memory  714 , in the non-volatile memory  716 , and/or on a removable tangible computer-readable storage medium such as a CD or DVD. 
     From the foregoing, it will be appreciated that example methods, apparatus and articles of manufacture have been disclosed that identify sources of network streaming services. From the foregoing, it will be appreciated that methods, apparatus and articles of manufacture have been disclosed which enhance the operations of a computer to improve the correctness of and possibility to identify the sources of network streaming services. In some examples, computer operations can be made more efficient, accurate and robust based on the above techniques for performing source identification of network streaming services. That is, through the use of these processes, computers can operate more efficiently by relatively quickly performing source identification of network streaming services. Furthermore, example methods, apparatus, and/or articles of manufacture disclosed herein identify and overcome inaccuracies and inability in the prior art to perform source identification of network streaming services. 
     Example methods, apparatus, and articles of manufacture to identify the sources of network streaming services are disclosed herein. Further examples and combinations thereof include at least the following. 
     Example 1 is an apparatus that includes: 
     a coding format identifier to identify, from a received first audio signal representing a decompressed second audio signal, an audio compression configuration used to compress a third audio signal to form the second audio signal; and 
     a source identifier to identify a source of the second audio signal based on the identified audio compression configuration. 
     Example 2 is the apparatus of example 1, further including: 
     a time-frequency analyzer to perform a first time-frequency analysis of a first block of the first audio signal according to a first trial compression configuration, and perform a second time-frequency analysis of the first block of the first audio signal according to a second trial compression configuration; 
     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 between the first trial compression configuration and the second trial compression configuration as the audio compression configuration based on the first compression artifact and the second compression artifact. 
     Example 3 is the apparatus of example 2, wherein the controller selects between the first trial compression configuration and the second trial compression configuration based on the first compression artifact and the second compression artifact includes comparing the first compression artifact and the second compression artifact. 
     Example 4 is the apparatus of example 2, wherein: 
     the time-frequency analyzer performs a third time-frequency analysis of a second block of the first audio signal according to the first trial compression configuration, and performs a fourth time-frequency analysis of the second block of the first audio signal according to the second trial compression configuration; 
     the artifact computer determines 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 selects between the first trial compression configuration and 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. 
     Example 5 is the apparatus of example 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, wherein the controller selects between the first trial compression configuration and the second trial compression configuration as the audio compression configuration by 
     comparing the first score and the second score. 
     Example 6 is the apparatus of example 5, wherein the post processor combines the first compression artifact and the third compression artifact to form the first score by: 
     mapping the first compression artifact and a first offset associated with the first compression artifact to a first polar coordinate; 
     mapping the third compression artifact and a second offset associated with the second compression artifact to a second polar coordinate; and 
     computing the first score as a circular mean of the first polar coordinate and the second polar coordinate. 
     Example 7 is the apparatus of example 1, wherein the first audio signal is recorded at a media presentation device. 
     Example 8 is a method that includes: 
     receiving a first audio signal that represents a decompressed second audio signal; 
     identify, from the first audio signal, an audio compression configuration used to compress a third audio signal to form the second audio signal; and 
     identifying a source of the second audio signal based on the identified audio compression configuration. 
     Example 9 is the method of example 8, wherein the identifying the source of the 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. 
     Example 10 is the method of example 8, wherein the identifying, from the first audio signal, the audio compression configuration includes: 
     performing a first time-frequency analysis of a first block of the first audio signal according to a first trial compression configuration; 
     determining a first compression artifact resulting from the first time-frequency analysis; 
     performing a second time-frequency analysis of the first block of the first audio signal according to a second trial compression configuration; 
     determining a second compression artifact resulting from the second time-frequency analysis; and 
     selecting between the first trial compression configuration and the second trial compression configuration as the audio compression configuration based on the first compression artifact and the second compression artifact. 
     Example 11 is the method of example 10, wherein selecting between the first trial compression configuration and the second trial compression configuration based on the first compression artifact and the second compression artifact includes comparing the first compression artifact and the second compression artifact. 
     Example 12 is the method of example 10, further including: 
     performing a third time-frequency analysis of a second block of the first audio signal according to the first trial compression configuration; 
     determining a third compression artifact resulting from the third time-frequency analysis; 
     performing a fourth time-frequency analysis of the second block of the first audio signal according to the second trial compression configuration; 
     determining a fourth compression artifact resulting from the fourth time-frequency analysis; and 
     selecting between the first trial compression configuration and 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. 
     Example 13 is the method of example 12, wherein selecting between the first trial compression configuration and 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 includes: 
     combining the first compression artifact and the third compression artifact to form a first score; 
     combining the second compression artifact and the fourth compression artifact to form a second score; and 
     comparing the first score and the second score. 
     Example 14 is the method of example 13, wherein the combining the first compression artifact and the third compression artifact to form the first score includes: 
     mapping the first compression artifact and a first offset associated with the first compression artifact to a first polar coordinate; 
     mapping the third compression artifact and a second offset associated with the second compression artifact to a second polar coordinate; and 
     computing the first score as a circular mean of the first polar coordinate and the second polar coordinate. 
     Example 15 is the method of example 8, wherein the first audio signal is recorded at a media presentation device. 
     Example 16 is the method of example 8, wherein the audio compression configuration indicates at least one of a time-frequency transform, a window function, or a window length. 
     Example 17 is a non-transitory computer-readable storage medium storing instructions that, when executed, cause a machine to perform operations including: 
     receiving a first audio signal that represents a decompressed second audio signal; 
     identify, from the first audio signal, an audio compression configuration used to compress a third audio signal to form the second audio signal; and 
     identifying a source of the second audio signal based on the identified audio compression configuration. 
     Example 18 is the non-transitory computer-readable storage medium of example 17, including further instructions that, when executed, cause the machine to identify the source of the second audio signal based on the identified audio compression configuration by: 
     identifying a coding format based on the identified audio compression configuration; and 
     identifying the source based on the coding format. 
     Example 19 is the non-transitory computer-readable storage medium of example 17, including further instructions that, when executed, cause the machine to identify, from the first audio signal, the audio compression configuration by: 
     performing a first time-frequency analysis of a first block of the first audio signal according to a first trial compression configuration; 
     determining a first compression artifact resulting from the first time-frequency analysis; 
     performing a second time-frequency analysis of the first block of the first audio signal according to a second trial compression configuration; 
     determining a second compression artifact resulting from the second time-frequency analysis; and 
     selecting between the first trial compression configuration and the second trial compression configuration as the audio compression configuration based on the first compression artifact and the second compression artifact. 
     Example 20 is the non-transitory computer-readable storage medium of example 19, including further instructions that, when executed, cause the machine to: 
     perform a third time-frequency analysis of a second block of the first audio signal according to the first trial compression configuration; 
     determine a third compression artifact resulting from the third time-frequency analysis; 
     perform a fourth time-frequency analysis of the second block of the first audio signal according to the second trial compression configuration; 
     determine a fourth compression artifact resulting from the fourth time-frequency analysis; and 
     select between the first trial compression configuration and 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. 
     Example 21 is the non-transitory computer-readable storage medium of example 20, including further instructions that, when executed, cause the machine to select between the first trial compression configuration and 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 by: 
     combining the first compression artifact and the third compression artifact to form a first score; 
     combining the second compression artifact and the fourth compression artifact to form a second score; and 
     comparing the first score and the second score. 
     Example 22 is the non-transitory computer-readable storage medium of example 21, including further instructions that, when executed, cause the machine to combine the first compression artifact and the third compression artifact to form the first score by: 
     mapping the first compression artifact and a first offset associated with the first compression artifact to a first polar coordinate; 
     mapping the third compression artifact and a second offset associated with the second compression artifact to a second polar coordinate; and 
     computing the first score as a circular mean of the first polar coordinate and the second polar coordinate. 
     Example 23 is a method including: 
     receiving a first audio signal that represents a decompressed second audio signal, the second audio signal formed by compressing a third audio signal according to an audio compression configuration; 
     performing a first time-frequency analysis of a first block of the first audio signal according to a first trial compression configuration; 
     determining a first compression artifact resulting from the first time-frequency analysis; 
     performing a second time-frequency analysis of the first block of the first audio signal according to a second trial compression configuration; 
     determining a second compression artifact resulting from the second time-frequency analysis; and 
     selecting between the first trial compression configuration and the second trial compression configuration as the audio compression configuration based on the first compression artifact and the second compression artifact. 
     Example 24 is the method of example 23, wherein the selecting between the first trial compression configuration and the second trial compression configuration as the audio compression configuration based on the first compression artifact and the second compression artifact includes comparing the first compression artifact and the second compression artifact. 
     Example 25 is the method of example 23, further including: 
     performing a third time-frequency analysis of a second block of the first audio signal according to the first trial compression configuration; 
     determining a third compression artifact resulting from the third time-frequency analysis; 
     performing a fourth time-frequency analysis of the second block of the first audio signal according to the second trial compression configuration; 
     determining a fourth compression artifact resulting from the fourth time-frequency analysis; and 
     selecting between the first trial compression configuration and 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. 
     Example 26 is the method of example 25, wherein the selecting between the first trial compression configuration and 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 includes: 
     combining the first compression artifact and the third compression artifact to form a first score; 
     combining the second compression artifact and the fourth compression artifact to form a second score; and 
     comparing the first score and the second score. 
     Example 27 is the method of example 26, wherein the combining the first compression artifact and the third compression artifact to form the first score includes: 
     mapping the first compression artifact and a first offset associated with the first compression artifact to a first polar coordinate; 
     mapping the third compression artifact and a second offset associated with the second compression artifact to a second polar coordinate; and 
     computing the first score as a circular mean of the first polar coordinate and the second polar coordinate. 
     “Including” and “comprising” (and all forms and tenses thereof) are used herein to be open ended terms. Thus, whenever a claim lists anything following any form of “include” or “comprise” (e.g., comprises, includes, comprising, including, having, etc.), it is to be understood that additional elements, terms, etc. may be present without falling outside the scope of the corresponding claim. As used herein, when the phrase “at least” is used as the transition term in a preamble of a claim, it is open-ended in the same manner as the term “comprising” and “including” are open ended. Conjunctions such as “and,” “or,” and “and/or” are inclusive unless the context clearly dictates otherwise. For example, “A and/or B” includes A alone, B alone, and A with B. In this specification and the appended claims, the singular forms “a,” “an” and “the” do not exclude the plural reference unless the context clearly dictates otherwise. 
     Any references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein. 
     Although certain example methods, apparatus and articles of manufacture have been disclosed herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all methods, apparatus and articles of manufacture fairly falling within the scope of the claims of this patent.