Abstract:
Systems and methods are disclosed for encoding audio in a set-top box that is invoked by a user when listening to a broadcast audio signal from a radio, TV, streaming or other audio device. A detection and identification system comprising an audio encoder is integrated in a set-top box, where detection and identification of media is realized. The encoding automatically identifies characteristics of the media (e.g., the source of a particular piece of material) by embedding an inaudible code within the content. This code contains information about the content that can be decoded by a machine, but is not detectable by human hearing. The embedded code may be used to provide programming information to the view or audience measurement date to the provider.

Description:
TECHNICAL FIELD 
     The present disclosure relates to encoding and decoding broadcast or recorded segments such as broadcasts transmitted over the air, via cable, satellite or otherwise, and video, music or other works distributed on previously recorded media, and more specifically, processing media data within a set-top box (STB) that includes encoding/decoding, for subsequent use in media and/or market research. 
     BACKGROUND INFORMATION 
     There is considerable interest in monitoring and measuring the usage of media data accessed by an audience via a network or other source. In order to determine audience interest and what audiences are being presented with, a user&#39;s system may be monitored for discrete time periods while connected to a network, such as the Internet. 
     There is also considerable interest in providing market information to advertisers, media distributors and the like which reveal the demographic characteristics of such audiences, along with information concerning the size of the audience. Further, advertisers and media distributors would like the ability to produce custom reports tailored to reveal market information within specific parameters, such as type of media, user demographics, purchasing habits and so on. In addition, there is substantial interest in the ability to monitor media audiences on a continuous, real-time basis. This becomes very important for measuring streaming media data accurately, because a snapshot or event generation fails to capture the ongoing and continuous nature of streaming media data usage. 
     Based upon the receipt and identification of media data, the rating or popularity of various web sites, channels and specific media data may be estimated. It would be advantageous to determine the popularity of various web sites, channels and specific media data according to the demographics of their audiences in a way which enables precise matching of data representing media data usage with user demographic data. 
     As disclosed in U.S. Pat. No. 7,460,827 to Schuster, et al. and U.S. Pat. No. 7,222,071 to Neuhauser, et al., which are hereby incorporated by reference in their entirety herein, specialized technology exists where a small, pager-size, specially-designed receiving stations called Portable People Meters (PPM) allow for the tracking of media exposure for users/panelists. In these applications, the embedded audio signal or ID code is picked up by one or more PPMs, which capture the encoded identifying signal, and store the information along with a time stamp in memory for retrieval at a later time. A microphone contained within the PPM receives the audio signal, which contains within it the ID code. 
     One of the goals of audience measurement is to identify the audience for specific channel viewing. With the HDTV and Digital age upon us, nearly every household has a STB attached to their TV, this allows for access to viewing habits and other household penetration. Therefore it would be advantageous to integrate audio encoding technology with one or more STBs for monitoring purposes. Furthermore, due to the STB&#39;s advanced design, performance and scalability, the STB does not only supply high real-time performance affordably, but can also be easily remotely reprogrammed for new configurations, updates, upgrades and applications. The integration of audio encoding technology with STB devices would eliminate unnecessary equipment and reduce associated costs. 
     SUMMARY 
     Under an exemplary embodiment, a detection and identification system is integrated with a Set-top box (STB), where a system for audio encoding is implemented within a STB. The encoding automatically identifies, at a minimum, the source of a particular piece of material by embedding an inaudible code within the content. This code contains information about the content that can be decoded by a machine, but is not detectable by human hearing. 
     An STB, for the purposes of this disclosure, may be simply defined as a computerized device that processes digital information. The STB may come in many forms and can have a variety of functions. Digital Media Adapters, Digital Media Receivers, Windows Media Extender and most video game consoles are also examples of set-top boxes. Currently the type of TV set-top box most widely used is one which receives encoded/compressed digital signals from the signal source (e.g., the content provider&#39;s headend) and decodes/decompresses those signals, converting them into analog signals that an analog (SDTV) television can understand. The STB accepts commands from the user (often via the use of remote devices such as a remote control) and transmits these commands back to the network operator through some sort of return path. The STB preferably has a return path capability for two-way communication. 
     STBs can make it possible to receive and display TV signals, connect to networks, play games via a game console, surf the Internet, interact with Interactive Program Guides (IPGs), virtual channels, electronic storefronts, walled gardens, send e-mail, and videoconference. Many STBs are able to communicate in real time with devices such as camcorders, DVD and CD players, portable media devices and music keyboards. Some have large dedicated hard-drives and smart card slots to insert smart cards into for purchases and identification. 
     For this application the following terms and definitions shall apply: 
     The term “data” as used herein means any indicia, signals, marks, symbols, domains, symbol sets, representations, and any other physical form or forms representing information, whether permanent or temporary, whether visible, audible, acoustic, electric, magnetic, electromagnetic or otherwise manifested. The term “data” as used to represent predetermined information in one physical form shall be deemed to encompass any and all representations of corresponding information in a different physical form or forms. 
     The terms “media data” and “media” as used herein mean data which is widely accessible, whether over-the-air, or via cable, satellite, network, internetwork (including the Internet), print, displayed, distributed on storage media, or by any other means or technique that is humanly perceptible, without regard to the form or content of such data, and including but not limited to audio, video, audio/video, text, images, animations, databases, broadcasts, displays (including but not limited to video displays, posters and billboards), signs, signals, web pages, print media and streaming media data. 
     The term “research data” as used herein means data comprising (1) data concerning usage of media data, (2) data concerning exposure to media data, and/or (3) market research data. 
     The term “presentation data” as used herein means media data or content other than media data to be presented to a user. 
     The term “ancillary code” as used herein means data encoded in, added to, combined with or embedded in media data to provide information identifying, describing and/or characterizing the media data, and/or other information useful as research data. 
     The terms “reading” and “read” as used herein mean a process or processes that serve to recover research data that has been added to, encoded in, combined with or embedded in, media data. 
     The term “database” as used herein means an organized body of related data, regardless of the manner in which the data or the organized body thereof is represented. For example, the organized body of related data may be in the form of one or more of a table, a map, a grid, a packet, a datagram, a frame, a file, an e-mail, a message, a document, a report, a list or in any other form. 
     The term “network” as used herein includes both networks and internetworks of all kinds, including the Internet, and is not limited to any particular network or inter-network. 
     The terms “first”, “second”, “primary” and “secondary” are used to distinguish one element, set, data, object, step, process, function, activity or thing from another, and are not used to designate relative position, or arrangement in time or relative importance, unless otherwise stated explicitly. 
     The terms “coupled”, “coupled to”, and “coupled with” as used herein each mean a relationship between or among two or more devices, apparatus, files, circuits, elements, functions, operations, processes, programs, media, components, networks, systems, subsystems, and/or means, constituting any one or more of (a) a connection, whether direct or through one or more other devices, apparatus, files, circuits, elements, functions, operations, processes, programs, media, components, networks, systems, subsystems, or means, (b) a communications relationship, whether direct or through one or more other devices, apparatus, files, circuits, elements, functions, operations, processes, programs, media, components, networks, systems, subsystems, or means, and/or (c) a functional relationship in which the operation of any one or more devices, apparatus, files, circuits, elements, functions, operations, processes, programs, media, components, networks, systems, subsystems, or means depends, in whole or in part, on the operation of any one or more others thereof. 
     The terms “communicate,” and “communicating” and as used herein include both conveying data from a source to a destination, and delivering data to a communications medium, system, channel, network, device, wire, cable, fiber, circuit and/or link to be conveyed to a destination and the term “communication” as used herein means data so conveyed or delivered. The term “communications” as used herein includes one or more of a communications medium, system, channel, network, device, wire, cable, fiber, circuit and link. 
     The term “processor” as used herein means processing devices, apparatus, programs, circuits, components, systems and subsystems, whether implemented in hardware, tangibly-embodied software or both, and whether or not programmable. The term “processor” as used herein includes, but is not limited to one or more computers, hardwired circuits, signal modifying devices and systems, devices and machines for controlling systems, central processing units, programmable devices and systems, field programmable gate arrays, application specific integrated circuits, systems on a chip, systems comprised of discrete elements and/or circuits, state machines, virtual machines, data processors, processing facilities and combinations of any of the foregoing. 
     The terms “storage” and “data storage” as used herein mean one or more data storage devices, apparatus, programs, circuits, components, systems, subsystems, locations and storage media serving to retain data, whether on a temporary or permanent basis, and to provide such retained data. 
     The present disclosure illustrates systems and methods for implementing audio encoding technology within a STB. Under various disclosed embodiments, one or more STBs are equipped with hardware and/or software to monitor an audience member&#39;s viewing and/or listening habits. The STBs are connected between a media device (e.g., television) and an external source of signal. In addition to converting a signal into content which is can be displayed on the television screen, the STB uses audio encoding technology to encode/decode the ancillary code within the source signal which can assist in producing research data. 
     By monitoring an audience member&#39;s media habits, the research data is manipulated where the media habits of one or more audience members can be reliably obtained to provide market information to advertisers, media distributors and the like which reveals the demographic characteristics of such audiences, along with information concerning the size of the audience. In certain embodiments, the technology may be used to simultaneously return applicable advertisements on a media device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is an exemplary functional block diagram of an encoder running On a STB; 
         FIG. 1B  is an exemplary functional block diagram of an encoder running on the Video Decoder Chip; 
         FIG. 1C  is an exemplary functional block diagram of an encoder running on a media processor CPU; 
         FIG. 2  is an exemplary diagram of an encoding process running On a STB; 
         FIG. 3A  is an exemplary block diagram overview of an encoder running on a main CPU; 
         FIG. 3B  is an exemplary state diagram of an encoder running in a STB according to one embodiment; 
         FIG. 4  is an exemplary block diagram of a media box under an alternate embodiment; 
         FIG. 5A  is an exemplary diagram of an encoder running in a STB according to one embodiment; 
         FIG. 5B  is an exemplary diagram of an encoder and decoder running in a STB; 
         FIG. 5C  is an exemplary diagram of an encoder running inside the STB and a decoder on external USB stick; and 
         FIG. 5D  is an exemplary diagram of a media box connected to the STB and to a media device. 
     
    
    
     DETAILED DESCRIPTION 
     Various embodiments of the present invention will be described herein below with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. 
     Under an exemplary embodiment, a system is implemented in a Set Top Box (STB) for gathering research data using encoding technology (e.g., CBET) concerning exposure of a user of the STB to audio and/or visual media. The present invention also relates to encoding and decoding broadcast or recorded segments such as broadcasts transmitted over the air, via cable, satellite or otherwise, and video, music or other works distributed on previously recorded media within the STB, as well as monitoring audience exposure to any of the foregoing. An exemplary process for gathering research data comprises transducing acoustic energy to audio data, receiving media data in non-acoustic form in a STB and producing research data based on the audio data and based on the media data and/or metadata of the media data. 
     The STB in the present disclosure relates to any consumer electronic devices capable to receive media/video content including digital video broadcast (DVB) standards and present the content to a user. In the case of video content, the development of IP networks and broadband/ADSL allow video content of good quality to be delivered as Internet Protocol television (IPTV) in the set-top boxes. Digital television may be delivered under a variety of DVB (Digital Video Broadcast) standards, such as DVB, DVB-S, DVB-S2, DVB-C, DVB-T and DVB-T2. The STB&#39;s may accept content from terrestrial, satellite, cable and/or streaming media via IP network. 
     An exemplary STB comprises a frontend which includes a tuner and a DVB demodulator. The frontend receives a raw signal from antenna or cable, and the signal is converted by the frontend into transport (MPEG) stream. Satellite equipment control (SEC) may also be provided in the case of satellite antenna setup. Additionally, a conditional access (CA) module or smartcard slot is provided to perform real-time decoding of encrypted transport stream. Demuxer filters incoming DVB stream and splits a transport stream into video and audio parts. The transport stream can contain some special streams like teletext or subtitles. Separated video and audio streams are preferably 
     Numerous types of research operations are possible utilizing the STB technology, including, without limitation, television and radio program audience measurement wherein the broadcast signal is embedded with metadata. Because the STB is capable of monitoring any nearby encoded media, the STB may also be used to determine characteristics of received media and monitor exposure to advertising in various media, such as television, radio, internet audio, and even print advertising. For the desired type of media and/or market research operation to be conducted, particular activity of individuals is monitored, or data concerning their attitudes, awareness and/or preferences is gathered. In certain embodiments, research data relating to two or more of the foregoing are gathered, while in others only one kind of such data is gathered. 
     Turning to  FIG. 1A , STB  100  is disclosed, comprising an encoder  110 , media processor  106  and video decoder IC  108 . STB  100  receives input  112  from a media source  102  which may be a cable, satellite, terrestrial and/or streaming media via an IP network. STB  100  outputs  114  encoded media to a media presentation device  104 , which may be a television under one exemplary embodiment. The output may comprise coaxial cable output, optical output, composite video, S-Video, component video, HDMI/DVI, and/or any other suitable means for outputting media data. STB  100  comprises media processor  106 , encoder  110 , and video decoder IC  108 . Media processor  106  is configured to perform media processing functions including, but not limited to, media tuning, automatic gain control, analog-to-digital conversion, along with any necessary forward error correction and demultiplexing to the incoming media signal received at input  112 . Media processor  106  is communicatively coupled to A/V decoder IC  108  that digitizes and decodes baseband analog video into digital component video and also may convert audio waves into PCM digital code and/or decompress audio. 
     In the embodiment of  FIG. 1A , encoder  110  is communicatively coupled to media processor  106  and A/V decoder  108  in STB  100 . As incoming media is received by media processor  106 , a an audio portion is forwarded to encoder  110  for encoding. During encoding, a number of preliminary operations are carried out in preparation for encoding one or more messages into audio data. First, the content of a message to be encoded is defined, where the message will typically characterize the media to be encoded. In certain embodiments this is achieved by selecting from a plurality of predefined messages, while in others the content of the message is defined through a user input or by data received from a further system (not shown). In still others the identity of the message content is fixed. 
     Once the content of the message is known, a sequence of symbols is assigned to represent the specific message. The symbols are selected from a predefined set of alphabet of code symbols. In certain embodiments the symbol sequences are preassigned to corresponding predefined messages. When a message to be encoded is fixed, as in a station ID message, encoding operations may combined to define a single invariant message symbol sequence. Subsequently, a plurality of substantially single-frequency code components are assigned to each of the message symbols. 
     When the message is encoded, each symbol of the message is represented in the audio data by its corresponding plurality of substantially single-frequency code components. Each of such code components occupies only a narrow frequency band so that it may be distinguished from other such components as well as noise with a sufficiently low probability of error. It is recognized that the ability of an encoder or decoder to establish or resolve data in the frequency domain is limited, so that the substantially single-frequency components are represented by data within some finite or narrow frequency band. Moreover, there are circumstances in which is advantageous to regard data within a plurality of frequency bands as corresponding to a substantially single-frequency component. This technique is useful where, for example, the component may be found in any of several adjacent bands due to frequency drift, variations in the speed of a tape or disk drive, or even as the result of an incidental or intentional frequency variation inherent in the design of a system. 
     In addition, digitized audio signals are supplied to encoder  110  for masking evaluation, pursuant to which the digitized audio signal is separated into frequency components, for example, by Fast Fourier Transform (FFT), wavelet transform, or other time-to-frequency domain transformation, or else by digital filtering. Thereafter, the masking abilities of audio signal frequency components within frequency bins of interest are evaluated for their tonal masking ability, narrow band masking ability and broadband masking ability (and, if necessary or appropriate, for non-simultaneous masking ability). Alternatively, the masking abilities of audio signal frequency components within frequency bins of interest are evaluated with a sliding tonal analysis. 
     More specific information regarding the encoding process described above, along with several advantageous and suitable techniques for encoding audience measurement data in audio data are disclosed in U.S. Pat. No. 7,640,141 to Ronald S. Kolessar and U.S. Pat. No. 5,764,763 to James M. Jensen, et al., which are assigned to the assignee of the present application, and which are incorporated by reference in their entirety herein. Other appropriate encoding techniques are disclosed in U.S. Pat. No. 5,579,124 to Aijala, et al., U.S. Pat. Nos. 5,574,962, 5,581,800 and 5,787,334 to Fardeau, et al., U.S. Pat. No. 5,450,490 to Jensen, et al., and U.S. Pat. No. 6,871,180, in the names of Neuhauser, et al., each of which is assigned to the assignee of the present application and all of which are incorporated herein by reference in their entirety. 
     Data to be encoded is received and, for each data state corresponding to a given signal interval, its respective group of code components is produced, and subjected to level adjustment and relevant masking evaluations. Signal generation may be implemented, for example, by means of a look-up table storing each of the code components as time domain data or by interpolation of stored data. The code components can either be permanently stored or generated upon initialization of the STB  100  and then stored in memory, such as in RAM, to be output as appropriate in response to the data received. The values of the components may also be computed at the time they are generated. 
     Level adjustment is carried out for each of the code components based upon the relevant masking evaluations as discussed above, and the code components whose amplitude has been adjusted to ensure inaudibility are added to the digitized audio signal. Depending on the amount of time necessary to carry out the foregoing processes, it may be desirable to delay the digitized audio signal by temporary storage in memory. If the audio signal is not delayed, after an FFT and masking evaluation have been carried out for a first interval of the audio signal, the amplitude adjusted code components are added to a second interval of the audio signal following the first interval. If the audio signal is delayed, however, the amplitude adjusted code components can instead be added to the first interval and a simultaneous masking evaluation may thus be used. Moreover, if the portion of the audio signal during the first interval provides a greater masking capability for a code component added during the second interval than the portion of the audio signal during the second interval would provide to the code component during the same interval, an amplitude may be assigned to the code component based on the non-simultaneous masking abilities of the portion of audio signal within the first interval. In this fashion both simultaneous and non-simultaneous masking capabilities may be evaluated and an optimal amplitude can be assigned to each code component based on the more advantageous evaluation. 
     In certain applications, such as in broadcasting, or analog recording (as on a conventional tape cassette), the encoded audio signal in digital form is converted to analog form by a digital-to-analog converter (DAC) discussed below in connection with  FIG. 4 . However, when the signal is to be transmitted or recorded in digital form, the DAC may be omitted. 
     Still other suitable encoding techniques are the subject of PCT Publication WO 00/04662 to Srinivasan, U.S. Pat. No. 5,319,735 to Preuss, et al., U.S. Pat. No. 6,175,627 to Petrovich, et al., U.S. Pat. No. 5,828,325 to Wolosewicz, et al., U.S. Pat. No. 6,154,484 to Lee, et al., U.S. Pat. No. 5,945,932 to Smith, et al., PCT Publication WO 99/59275 to Lu, et al., PCT Publication WO 98/26529 to Lu, et al., and PCT Publication WO 96/27264 to Lu, et al, all of which are incorporated herein by reference. 
     In certain embodiments, the encoder  110  forms a data set of frequency-domain data from the audio data and the encoder processes the frequency-domain data in the data set to embed the encoded data therein. Where the codes have been formed as in the Jensen, et al. U.S. Pat. No. 5,764,763 or U.S. Pat. No. 5,450,490, the frequency-domain data is processed by the encoder  25  to embed the encoded data in the form of frequency components with predetermined frequencies. Where the codes have been formed as in the Srinivasan PCT Publication WO 00/04662, in certain embodiments the encoder processes the frequency-domain data to embed code components distributed according to a frequency-hopping pattern. In certain embodiments, the code components comprise pairs of frequency components modified in amplitude to encode information. In certain other embodiments, the code components comprise pairs of frequency components modified in phase to encode information. Where the codes have been formed as spread spectrum codes, as in the Aijala, et al. U.S. Pat. No. 5,579,124 or the Preuss, et al. U.S. Pat. No. 5,319,735, the encoder comprises an appropriate spread spectrum encoder. 
     The media measurement arrangements in  FIG. 1A , as well as the other embodiments detailed below, are particularly advantageous for identifying audience and content in STBs as the configuration takes advantage of the advanced design, performance and scalability of STBs. Additionally STBs can also be remotely reprogrammed for new configurations, updates, upgrades and applications. Conventional STBs may be modified by software and/or hardware changes to carry out a research operation. In alternate embodiments, STBs are redesigned and substantially reconstructed for this purpose. In certain embodiments, the STB itself is operative to gather research data. In certain embodiments, the STB emits data that causes another device to gather research data. In certain embodiments, the STB is operative both to gather research data and to emit data that causes another device to gather research data. In certain embodiments, the STB wirelessly, or using wires, communicates (e.g. a wireless internet connection or other computer network) the research data with a service server. 
     Another advantage of integrating encoding in a STB is that encoding may be performed directly at the source in real-time, thus reducing or eliminating the need to encode at the station or broadcaster. This allows cable providers, satellite TV network and STB manufacturers to provide download capability of the encoding application and the encoding engine over the air to a user&#39;s STB. In such an embodiment, the STB would have access to a look up table in which a unique code is assigned for each TV channel. During Broadcast, the encoder, operating at the video decoder output level, will encode the incoming broadcast signal for that channel. It is also possible to determine which channel was being viewed by embedding a different code for each channel. Further, by embedding both the encoder and the decoder the STB allows for real time encoding. In this embodiment, the output signal to the TV may be simultaneously decoded in real time. In this embedment, data is saved in a dedicated memory/storage, and communicated from the STB to the central media monitoring server for analysis. 
     Since many STBs are “on” even when the audio-visual device is “off”, encoding the audio signal allows media monitoring organizations to determine whether the media device (e.g., television) is on by decoding the room audio. This can be accomplished by using either a personal people meter (PPM™) worn by a panelist, by an embedded decoder in the STB, or by having a decoder and microphone connected to the STB via USB. As an alternative embodiment, the encoder and decoder are housed in a dedicated box that is connected between the STB and the audio-visual device (e.g. a TV). The ultimate results are the same except that in this case the encoder/decoder are in their own box rather than integrated with a STB. This may be advantageous in applications where STBs are not necessary for the audience members media viewing, such as over the air TV broadcast. In all embodiments, if the source signal has been previously encoded, the decoder will identify the source and program content to complement STB&#39;s channel identification. 
     Accordingly, an encoder running on a STB has a number of advantages, in that the configuration can determine whether or not TV is “on”, identify person level demographics for those wearing a portable device (e.g., PPM), provides the capability to the STB manufacturer or service providers to target specific channels or programs be encoded or decoded by codes, perform real-time encoding of program segments, perform transparently to the audience member, allows for the creation of a “mega panel” due to the number of existing STBs in use, and the STB has many existing hardware and software technological advantages for gathering data (e.g., the STBs are Wi-Fi/Bluetooth enabled). 
     In an alternate embodiment illustrated in  FIG. 1B , STB  200  is arranged where encoder  210  (which has similar operative characteristics as encoder  110  in  FIG. 1A ) is incorporated within A/V decoder IC  208 . Just as in  FIG. 1A , the STB can provide the viewer with the program info (channel, program) as well as pulse-code modulation (PCM) audio. The encoder engine inserts appropriate codes in the audio and returns it back to the STB controller. Using principles of psychoacoustic masking discussed above, encoder  210  inserts tones into the audio spectrum of the station or network&#39;s source signal and the STB  200  communicates the encoded signal to an audio-visual device  104  (e.g. a television) via communication interface  114  (e.g. Coaxial Cable, Optical, Composite Video, S-Video, Component Video, HDMI/DVI, or a wireless means). The audio-visual device then displays the encoded broadcast signal which may have the capability to display meta-data such as the programming information. If necessary, encoder  210  may also serve the function of decoding a previously encoded signal. In still another exemplary embodiment,  FIG. 1C  illustrates a STB  300  where encoder  310  of  FIGS. 1A-B , is embedded on the media processor  306 . Encoded audio is forwarded to A/V decoder  108  and transmitted  114  to a user&#39;s media device  104 . 
     Turning to the exemplary embodiment in  FIG. 2 , a more detailed illustration of a STB, similar to the ones illustrated in  FIGS. 1A-C , is shown. Here, a CPU  416  controls and/or communicates directly/indirectly with demultiplexer  408 , decoder  410 , modem  414 , card reader  410 , memory  422 , video digital-to-analog converter (DAC)  412 , audio DAC  424  and encoder  418 . While tuner  404  receives media from source signal  400 , modem  414  accepts interactive or other data  428  received from a computer-based network. Card reader  420  accepts smart cards and/or cable cards for identifying a user and for allowing the user to further interact with the set-top box, either alone, or in conjunction with user inputs  426 , which may be a keyboard, infrared device, track ball, etc. 
     As a source signal is received  400 , tuner  404  down-converts the incoming carrier to an intermediate frequency (IF). The IF signal is demodulated into in-phase (“I”) and quadrature phase (“Q”) carrier components which are then A-D converted into a plurality of multi-bit data streams (e.g., 6-bit) for digital demodulation  406  and subsequent processing such as forward-error correction (FEC) in which the Reed-Solomon check/correction, de-interleaving and Viterbi decoding are carried out. A resulting transport stream is then forwarded to demultiplexer  408  which has responsibility for transmitting signals to respective video and audio (MPEG) decoders ( 410 ). 
     Decoder  410  is responsible for composing a continuous moving picture from the received frames from demultiplexer  408 . Additionally, decoder  410  performs necessary data expansion, inverse DCT, interpolation and error correction. The reconstituted frames may be built up inside the decoder&#39;s DRAM (not show), or may also use memory  422 . Decoder  410  outputs a pulse train containing the necessary A/V data (e.g., Y, Cr and Cb values for the pixels in the picture), which is communicated to video DAC  412  for conversion (and possible PAL encoding, if necessary). 
     In addition, decoder  410  forwards audio to encoder  418 , which encodes audio data prior to converting audio in Audio DAC  424  and presenting the audio (L-R) and/or video to media device  402 . In certain embodiments, encoder  418  embeds audience measurement data in the audio data, and may be embodied as software running on the STB, including embodiments in which the encoding software is integrated or coupled with another player running on the system of  FIG. 2 . In alternate embodiments, encoder  418  may comprise a device coupled with the STB such as a peripheral device, or a board, such as a soundboard. In certain embodiments, the board is plugged into an expansion slot of the STB. In certain embodiments, the encoder  418  is programmable such that it is provided with encoding software prior to coupling with the user system or after coupling with the user system. In these embodiments, the encoding software is loaded from a storage device or from the audio source or another source, or via another communication system or medium. 
     In certain embodiments, the encoder  418  encodes audience measurement data as a further encoded layer in already-encoded audio data, so that two or more layers of embedded data are simultaneously present in the audio data. The layers should be arranged with sufficiently diverse frequency characteristics so that they may be separately detected. In certain of these embodiments the code is superimposed on the audio data asynchronously. In other embodiments, the code is added synchronously with the preexisting audio data. In certain ones of such synchronous encoding embodiments data is encoded in portions of the audio data which have not previously been encoded. At times the user system receives both audio data (such as streaming media) and audience measurement data (such as source identification data) which, as received, is not encoded in the audio data but is separate therefrom. In certain embodiments, the STB may supply such audience measurement data to the encoder  418  which serves to encode the audio data therewith. 
     Under one embodiment, the audience measurement data is source identification data, content identification code, data that provides information about the received audio data, demographic data regarding the user, and/or data describing the user system or some aspect thereof, such as the user agent (e.g. player or browser type), operating system, sound card, etc. The audience measurement data can also include an identification code. In certain embodiments for measuring exposure of any audience member to audio data obtained from the Internet, such as streaming media, the audience measurement data comprises data indicating that the audio data was obtained from the Internet, the type of player and/or source identification data. 
       FIG. 3A  illustrates an embodiment of an encoder ( 528 ) running off of the main CPU of set top box (STB) chip  500 . Similar to  FIG. 2 , a source signal  502  is received at one or more inputs of STB chip  500  (not shown). STB chip  500  is also communicatively coupled to smart card/cable card input  504 , hard drive (HDD)  506  and DRAM/SDRAM/EEPROM memory  508 . It is understood by those having ordinary skill in the art that the aforementioned features may be integrated in STB chip  500  as well. Source signal  502  is received at tuner block  510 , which performs down-conversion and further communicates with conditional access (CA) block  512  to perform real-time decoding of encrypted transport stream. 
     CA block  512  is communicatively coupled with main CPU  520 , which in turn processes controller data provided by tuner controller  522 , CA controller  524  and media controller  526 . Additionally, main CPU  520  also may receive inputs from watch dog timer  530  and time stamp  532 . After down-conversion from tuner  510 , the incoming carrier for source signal  502  is demodulated and A-D converted into a plurality of multi-bit data streams for digital demodulation and subsequent processing. A resulting transport stream is then forwarded to demultiplexer  514  which has responsibility for transmitting signals to media decoder  518 , which, in the embodiment of  FIG. 3A , is powered by embedded CPU  516 . 
     Media Decoder  518  processes a stream from demultiplexer  514  is responsible for composing a continuous moving picture from the received frames from demultiplexer  408 . Additionally, decoder  410  performs necessary data expansion, inverse DCT, interpolation and error correction. The reconstituted frames may be built up inside the decoder&#39;s DRAM  508  or other suitable memory. Decoder  518  outputs a pulse train containing the necessary A/V data, which is communicated to video DAC  536  for conversion and output  542  to media device  544 . 
     Decoder  518  forwards audio to encoder  528 , which encodes audio data prior to converting audio in Audio DAC  534  and presenting the audio (L-R) to media device  544 . Just as described above in connection with  FIG. 2 , encoder  528  embeds audience measurement data in the audio data, and may be embodied as software running on the STB chip, including embodiments in which the encoding software is integrated or coupled with another player running on the system of  FIG. 2 . In alternate embodiments, encoder  528  may comprise a device coupled with the STB chip such as a peripheral device, or a board. In certain embodiments, encoder  528  is programmable such that it is provided with encoding software prior to coupling with the user system or after coupling with the user system. In these embodiments, the encoding software is loaded from a storage device or from the audio source or another source, or via another communication system or medium. 
       FIG. 3B  illustrates an alternate embodiment from the one disclosed in  FIG. 3A , where STB chip  612  of STB  600  is separate from tuner  510 . Additionally, digital-analog converter  640  is provided in audio codec block  638 , which is communicatively coupled to STB chip  612 . Codec  638  may be lossy or lossless, and may be configured to accept a wide variety of container formats, such as Ogg, ASF, DivX, as well as containers defined as ISO standards, such as MPEG transport stream, MPEG program stream, MP4 and ISO base media file format. The embodiment of  FIG. 3B  may be particularly advantageous in cases where multimedia data is received through a packetized network, or otherwise requires compression/decompression for playback. 
       FIG. 4  illustrates yet another embodiment, where the encoder illustrated in any of  FIGS. 1A-3B  is embodied in a media box  702 , which is communicatively coupled between STB  700  and media device  706 . In this embodiment, media box  702  is a dedicated box that encapsulates a small version of the encoder and/or decoder. A source signal  704  (e.g. CATV, satellite, antenna, Ethernet or another broadcasting method) is communicated via communication means to a STB  700  which processes the signal to produce a format compatible with the media device  706 . The signal from the STB  700  is communicated to the media box  702  where the signal may be encoded or decoded prior to being communicated to the media device where the media is reproduced. 
       FIG. 5A  discloses an exemplary encoding process, where, at the start  802  of an encoding process, source signal  832  is received in STB  800 , where tuner  804  down-converts the incoming carrier to an intermediate frequency (IF). The IF signal undergoes conditional access processing  806  and is demodulated  808  into “I” and “Q” carrier components  828  which are then A-D converted demultiplexed  810 , where the resulting signals are transmitted to decoder  812 , which produces audio output  814  and video output  816 . Video output is converted  822  and combined with audio prior to reproduction on media device  830 . Audio output  814  is provided to encoder  818 , which operates similarly to the encoders described above in connection with  FIGS. 1A-3B . A portion of the encoded audio is sampled  820  (e.g., 8K sample signal) prior to forwarding the encoded audio to audio DAC module  824 . The sampled audio may subsequently be used for audio matching and/or signature extraction within the STB or at a remote location. 
       FIG. 5B  illustrates another embodiment of the process in  FIG. 5A , where a microphone  932  is provided on the STB. Acoustic energy is detected by microphone (transducer)  932  and translated into detected audio data. Decoder  936  serves to decode the encoded data present in the detected audio data. The decoded data is either stored in an internal storage  938  to be communicated at a later time or else communicated from the STB  900  once decoded. In other embodiments, the STB  900  provides the detected audio data or a compressed version thereof to a storage device  938  for decoding elsewhere. The storage device  938  may be internal to the STB  900  as depicted in  FIG. 5B , or the storage device may be external to the STB  900  and coupled therewith to receive the data to be recorded. In still further embodiments, STB  900  receives and communicates audio data or a compressed version thereof to another device for subsequent decoding. In certain embodiments, the audio data is compressed by forming signal-to-noise ratios representing possible code components, such as in U.S. Pat. No. 5,450,490 or U.S. Pat. No. 5,764,763 both of which are assigned to the assignee of the present invention and are incorporated herein by reference in their entirety. The data to be decoded in certain embodiments may include data already encoded in the audio data when received by the user system, data encoded in the audio data by the user system, or both. 
     There are several possible embodiments of decoding techniques that can be implemented for use in the present invention. Several advantageous techniques for detecting encoded audience measurement data are disclosed in U.S. Pat. No. 5,764,763 to James M. Jensen, et al., which is assigned to the assignee of the present application, and which is incorporated by reference herein. Other appropriate decoding techniques are disclosed in U.S. Pat. No. 5,579,124 to Aijala, et al., U.S. Pat. Nos. 5,574,962, 5,581,800 and 5,787,334 to Fardeau, et al., U.S. Pat. No. 5,450,490 to Jensen, et al., and U.S. patent application Ser. No. 09/318,045, in the names of Neuhauser, et al., each of which is assigned to the assignee of the present application and all of which are incorporated herein by reference. 
     Still other suitable decoding techniques are the subject of PCT Publication WO 00/04662 to Srinivasan, U.S. Pat. No. 5,319,735 to Preuss, et al., U.S. Pat. No. 6,175,627 to Petrovich, et al., U.S. Pat. No. 5,828,325 to Wolosewicz, et al., U.S. Pat. No. 6,154,484 to Lee, et al., U.S. Pat. No. 5,945,932 to Smith, et al., PCT Publication WO 99/59275 to Lu, et al., PCT Publication WO 98/26529 to Lu, et al., and PCT Publication WO 96/27264 to Lu, et al., all of which are incorporated herein by reference. 
     In certain embodiments, decoding is carried out by forming a data set from the audio data collected by the portable monitor  100  and processing the data set to extract the audience measurement data encoded therein. Where the encoded data has been formed as in U.S. Pat. No. 5,764,763 or U.S. Pat. No. 5,450,490, the data set is processed to transform the audio data to the frequency domain. The frequency domain data is processed to extract code components with predetermined frequencies. Where the encoded data has been formed as in the Srinivasan PCT Publication WO 00/04662, in certain embodiments the remote processor  160  processes the frequency domain data to detect code components distributed according to a frequency-hopping pattern. In certain embodiments, the code components comprise pairs of frequency components modified in amplitude to encode information which are processed to detect such amplitude modifications. In certain other embodiments, the code components comprise pairs of frequency components modified in phase to encode information and are processed to detect such phase modifications. Where the codes have been formed as spread spectrum codes, as in the Aijala, et al. U.S. Pat. No. 5,579,124 or the Preuss, et al. U.S. Pat. No. 5,319,735, an appropriate spread spectrum decoder is employed to decode the audience measurement data. 
     Turning to  FIG. 5C , the microphone  1032 , analog-to-digital converter  1034 , decoder  1036  and storage  1038 , discussed in detail above with reference to  FIG. 5B , is embodied as a USB stick  1080 , which couples to STB  1000 . In addition to the advantages discussed above, the embodiment of  FIG. 5C  provides a convenient and effective way to effect decoding for audience measurement purposes. The embodiment of  FIG. 5D  is based on the illustration disclosed in  FIG. 4 , where media box  1116  receives multimedia output from STB  1100  via media output module  1114 . Here, media box  1116  contains both the encoding and decoding modules, and a microphone to capture ambient sound, similar to the embodiments in  FIGS. 5B-C . 
     Although various embodiments of the present invention have been described with reference to a particular arrangement of parts, features and the like, these are not intended to exhaust all possible arrangements or features, and indeed many other embodiments, modifications and variations will be ascertainable to those of skill in the art. 
     The Abstract of the Disclosure is provided to comply with 37 C.F.R. .sctn.1.72(b), requiring an abstract that will allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, it can be seen that various features are grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment.