GB2580707A

GB2580707A - Video signal receiving apparatus, transmitting apparatus and methods

Info

Publication number: GB2580707A
Application number: GB1901136.0A
Authority: GB
Inventors: Stuart Moore Nigel
Original assignee: Sony Corp
Current assignee: Sony Corp
Priority date: 2019-01-28
Filing date: 2019-01-28
Publication date: 2020-07-29
Also published as: WO2020157471A1; EP3918786A1; AU2020213954A1; GB201901136D0

Abstract

A video signal receiving apparatus comprising processor, input and output circuitry, the processor circuitry: controlling input circuitry to receive a first video signal; and identifying, in the first video signal, a second video signal retrieval indicator variably positioned relative to positions of one or more dummy second video signal retrieval indicators in the first video signal using a characteristic of the second video signal retrieval indicator which distinguishes it from the one or more dummy second video signal retrieval indicators, the characteristic being known to an intended receiver of the second video signal retrieval indicator; retrieving a second video signal in response to the identifying; identifying, in the first video signal, a second video signal initiation indicator variably positioned relative to the positions of one or more dummy second video signal initiation indicators using a characteristic of the initiation indicator which distinguishes it from the one or more dummy second video signal initiation indicators, the characteristic being known to an intended receiver of the second video signal initiation indicator; and controlling output circuitry to output the second video signal in response to identifying the second video signal initiation indicator.

Description

Intellectual Property Office Application No. GII1901136.0 RTM Date:23 July 2019 The following terms are registered trade marks and should be read as such wherever they occur in this document: DVB (page 5) Intellectual Property Office is an operating name of the Patent Office www.gov.uk /ipo VIDEO SIGNAL RECEIVING APPARATUS, TRANSMITTING APPARATUS AND METHODS

BACKGROUND

Field of the Disclosure

The present disclosure relates to a video signal receiving apparatus, transmitting apparatus and methods.

Description of the Related Art

The "background" description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in the background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present disclosure.

It is sometimes desirable to provide additional video content with video content selected by a user. For example, when a user is watching a television program, it is sometimes desirable to introduce advertisements (also known as "adverts" or "ads") which are played at predetermined intervals during the television program. The predetermined intervals during which such advertisements are played may be referred to as advertisement breaks (or "ad breaks").

Ad breaks have been around for many years. Traditionally, when the television program is provided by means of a broadcasted radio video signal, advertisements played during an ad break are also broadcasted by means of a radio video signal. In more recent times, however, with the development of higher bandwidth domestic internet connections and internet enabled set top boxes (STBs) and televisions (TVs), it has been possible for advertisements to be provided over the internet.

Thus, at the beginning of an ad break during a broadcasted television program, the video output provided by the STB or TV is switched from a broadcast video output to a network video output.

At the end of the ad break, the video output is then switched back to the broadcast video output.

Advantageously, this enables the advertisements shown during the ad break to be more easily tailored to the user of the STB or TV concerned. This is because information about the user (e.g. the type of TV shows they like, internet account information used by the user with the STB or TV or the like) can be gathered and transmitted over the network to an advertisement provider. An appropriate advertisement likely to be of relatively greater or of most interest to the user (based on the information about the user) can then be selected and transmitted to the STB or TV for display during the next ad break. This is much more difficult to do with traditional broadcasted advertisements which, by their very nature, are broadcast to a large number of STB or TVs and thus cannot be easily tailored to individual users. It will also be appreciated that the TV program itself may be provided over the internet rather than being broadcast. In this case, a switch from broadcast video output to network video output is not required. However, there is still a need to switch between different network video outputs to allow the advertisements to be shown during the ad break.

There is therefore a need to successfully manage the switch between outputting user-selected video content (e.g. a TV program) and outputting additional video content (e.g. advertisements during ad breaks). In particular, it is desirable to ensure that the switch occurs efficiently and that it is difficult for an unauthorised user to operate hardware and/or software to skip the additional video content (e.g. using an advertisement skipper or "ad skipper").

SUMMARY

The present disclosure is defined by the claims.

The foregoing paragraphs have been provided by way of general introduction, and are not intended to limit the scope of the following claims. The described embodiments, together with further advantages, will be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: Figure 1 schematically shows a video signal transmitting apparatus and a video signal receiving apparatus according to an embodiment; Figure 2 schematically shows a recording timeline of a TV program; Figures 3A to 3C schematically show a variation in the temporal positions of an advert retrieval indicator and an advert initiation indicator relative to those of respective dummy indicators for different ad breaks; Figures 4A to 4C schematically show a first variation of the technique exemplified in Figures 3A to 3C; and Figures 5A and 5B schematically show first methods carried out by the video signal receiving apparatus and video signal transmitting apparatus.

DESCRIPTION OF THE EMBODIMENTS

Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views.

Figure 1 shows a video signal transmitting apparatus 100 and a video signal receiving apparatus 105 according to an embodiment.

The video signal transmitting apparatus 100 comprises a radio frequency (RF) transmitter 101 for broadcasting a video signal using radio waves, a processor 102 for processing electronic instructions, memory 103 for storing the electronic instructions to be processed and input and output data associated with the electronic instructions and a storage medium 104 (e.g. in the form of a hard disk drive, solid state drive or the like) for long term storage of electronic information (e.g. software for controlling the operation of the video signal transmitting apparatus 105). Each of the RF transmitter 101, processor 102, memory 103 and storage medium 104 are implemented using appropriate circuitry, for example. The processor 102 controls the operation of each of the RF transmitter 101, memory 103 and storage medium 104.

The video signal receiving apparatus 105 comprises a radio frequency (RF) receiver 106 for receiving the video signal broadcast using radio waves, a processor 107 for processing electronic instructions, memory 108 for storing the electronic instructions to be processed and input and output data associated with the electronic instructions, a storage medium 109 (e.g. in the form of a hard disk drive, solid state drive or the like) for long term storage of electronic information (e.g. software for controlling the operation of the video signal receiving apparatus 105), a network interface 110 for sending and receiving electronic information over a network 112 (e.g. the internet) and an output 111 for outputting a video signal to a display device 114 (e.g. a television (TV)) for display of a video represented by that output video signal and/or to a video recording medium 115 (e.g. in the form of a hard disk drive, solid state drive or the like) for recording of the output video signal for later display on the display device 114. The video signal receiving apparatus 105, display device 114 and video recording medium 115 may be comprised within a single device or may be comprised within a plurality of separate devices. For example, the video signal receiving apparatus 105 and display device 114 may be comprised within a first device (e.g. a smart TV) and the video recording medium 115 may be comprised within a second, separate, device (e.g. a Universal Serial Bus (USB) storage drive connectable to the smart TV). Recording to video recording medium 115 and potentially also the configuration of 115 may be controlled by the first device. As another example, the display device 114 may be comprised within a first device (e.g. a TV) and the video signal receiving apparatus 105 and video recording medium 115 may be comprised within a second, separate, device (e.g. a personal video recorder (PVR) connectable to the TV). Each of the RF receiver 106, processor 107, memory 108, storage medium 109, network interface 110 and output 111 are implemented using appropriate circuitry, for example. The processor 102 controls the operation of each of the RF receiver 106, memory 108, storage medium 109, network interface and output 111.

In the embodiment of Figure 1, a server 113 is connected to the network 112 and a video signal representative of a video advertisement to be displayed on the display device 114 during an ad break is transmitted from the server 113 to the video signal receiving apparatus 105 over the network 112 in the form of packets of electronic information (e.g. in accordance with an appropriate Moving Picture Experts Group (MPEG) standard). The video signal of the advertisement is transmitted to the video signal receiving apparatus 105 in response to an electronic request transmitted by the video signal receiving apparatus 105 to the server 113 (the request is thus used to initiate retrieval of the video signal of the advertisement).

In one example, the transmitted advertisement is chosen from a plurality of advertisements using information known about the user of the video signal receiving apparatus 105 and stored in the server 113. This allows an advertisement appropriate to the user to be transmitted. In this sense, the advertisement is therefore personalised. The user information could include information about the user's location, shopping habits, preferred TV programs or TV applications, television make, model or specification or television interconnected hardware, subscription services (whether paid for or free) or any other information which the user has given permission to the operator of the server 113 to store. In one example, the user is allocated a user ID which uniquely identifies the user and which is stored in the storage medium 109. The request comprises the user ID. When the server 113 receives the request, it looks up the user ID in a database which relates the user IDs of a plurality of users with respective information about those users. A suitable advertisement is then selected based on the information of the user of the video signal receiving apparatus 105 identified by the user ID in the request (techniques for selecting a suitable advertisement based on user information are known in the art and are therefore not discussed in detail here). A video signal representative of the selected advertisement is then transmitted or communicated to the video signal receiving apparatus 105 over the network 112. In one example, this is achieved by the server 113 transmitting an eXtensible Markup Language (XML) document comprising a Uniform Resource Locator (URL) or Uniform Resource Identifier (URI) at which the selected advertisement is located or group of selected advertisements is located. The group may comprise a concatenation of advertisements. Individual advertisements in the group may be readily identifiable by identifying data for audit and/or tracking purposes for example in the XML document or a database. The video signal receiving apparatus 105 then accesses the URL or URI in order to start downloading the video signal representative of the selected advertisement. It will be appreciated that the server 113 may, in fact, be several servers serving different respective purposes (e.g. one server holding the user ID and information database and another server hosting the advertisement accessible using the URL or URI). Advertisements provided over the network 112 may be personalised or non-personalised in the present technique. For non-personalised advertisements, there is no need for the initial request to contain a user ID.

A video signal representative of content to be displayed on the display device 114 and/or stored on the video recording medium 115 and during which the ad break occurs (e.g. a movie, TV program or a recorded live event such as a live sporting or music event) is transmitted from the video signal transmitting apparatus 100 to the video signal receiving apparatus 105 using radio waves (e.g. in accordance with an appropriate Digital Video Broadcasting (DVB) or Advanced Television Systems Committee (ATSC) standard). The content is selected by the selection of a particular TV channel on which the desired video content is to be shown, for example.

Alternatively, the video signal representative of the content to be displayed and/or stored and during which the ad break occurs may be transmitted from the video signal transmitting apparatus 100 to the video signal receiving apparatus 105 over the network 112 in the form of packets of electronic information (e.g. in accordance with an appropriate Moving Picture Experts Group (MPEG) standard). In this case, the content is selected using an online video on-demand service, for example. The disclosure is also applicable to internet-delivered broadcasts in which the same content is delivered substantially at the same time to multiple users or devices, for example by multicasting from an edge server or servers. In these cases, the RF transmitter 101 of the video signal transmitting apparatus 100 is replaced with a network interface (not shown) for sending and receiving electronic information over the network 112 under the control of the processor 102.

In the description below, the content which includes the ad break is assumed to be a TV program 200 which is broadcast by the video signal transmitting apparatus 100 using radio waves and which is recorded on the video recording medium 115 for later display on the display device 114. However, it will be appreciated that the described technical principles would also be applied if the content is delivered over the network 112 (instead of being broadcast using radio waves), is displayed on the display device 114 (instead of or in addition to being recorded on the video recording medium 115) and/or is a different type of content (e.g. a film or a recorded live event instead of a TV program). In particular, it will be appreciated that the present technique may be applied to avoid skipping of ad breaks in live content which is continuously transmitted (i.e. transmitted without interruption) for display on the display device 114 (e.g. via radio waves or via the network 112) but which relies on adverts to be periodically provided during display of the live content by switching based on the presence of an advert retrieval and/or initiation indicator (see below). In the description below, a video signal broadcast using radio waves will be referred to as a broadcast video signal and a video signal transmitting over the network 112 will be referred to as a network video signal.

Figure 2 shows a recording timeline of the TV program 200. The TV program 200 is recorded in two parts 200A and 200B. The parts are separated by an ad break 201 comprising a number of consecutive video adverts 201A, 201B and 201C. The broadcast video signal representing the first part 200A of the TV program 200 comprises an advert retrieval indicator 202A and an advert initiation indicator 202B. The advert retrieval indicator 202A is a message instructing the video signal receiving apparatus 105 to retrieve a network video signal representative of each of the adverts 201A, 201B and 201C from the server 113. The advert initiation indicator 202B is a message instructing the video signal receiving apparatus 105 to temporarily stop recording the broadcast video signal and to instead record the retrieved network video signals representative of the adverts 201A, 201B and 2010. After recording of the final retrieved advert (advert 201C, in this case) is complete, the video signal receiving apparatus 105 resumes recording of the broadcast video signal in order to record the second part 200B of the TV program.

It is noted that, during the recording of the retrieved adverts 201A, 201B and 201C, the broadcast video signal does not contain any portion of the TV program 200. Rather, the broadcast video signal comprises one or more conventional video adverts during this time (so that viewers who do not have equipment which can retrieve adverts over the network 112 are presented with these conventional video adverts). In an embodiment, the ad break 201 is of a predetermined time duration and the playback duration of each advert (whether retrieved from the server 113 or whether included as a conventional advert in the broadcast video signal) is chosen such that the total advert playback duration matches this predetermined time duration.

This helps ensure that no portion of the TV program 200 is missed during the switch between the broadcast video signal and the network video signal.

In an embodiment, the advert retrieval indicator 202A occurs at a first predetermined time interval prior to the occurrence of the advert initiation indicator 202B and the advert initiation indicator 202B occurs at a second predetermined time interval prior to the start of the ad break 30 201.

The first predetermined time interval is determined to be sufficiently long such that the video adverts 201A, 201B and 201C retrieved from the server 113 are sufficiently buffered (e.g. in the memory 108) prior to the start of the ad break 201 to enable uninterrupted recording (for example, mitigating the possibility of buffer underflow) of the video adverts 201A, 201B and 201C during the ad break. However, the first predetermined time interval is also determined to be sufficiently short so as to reduce the likelihood that a user switches to the broadcast video signal comprising the TV program 200 (e.g. by changing channel) during the first predetermined time interval (in this situation, it is determined that the adverts 201A, 201B and 201C may not be retrieved in time for sufficient buffering to ensure their non-interrupted recording and therefore the conventional broadcast adverts will be recorded instead of the network provided adverts, the conventional broadcast adverts being likely to be of less relevance to the user). The first predetermined time interval may be between 5 and 10 seconds (for example) or, in some circumstances (e.g. if the ad break contains only a single, longer advert which needs to be buffered rather than a plurality of different consecutive adverts, the later ones of which can be buffered whilst the earlier ones are played back), up to 60 seconds (for example). More generally, the first predetermined time interval may correspond to the duration of advert 201A or a portion of advert 201A, for example (so that the longer the duration of advert 201A, the longer the first predetermined time interval in order to allow sufficient buffering time).

The second predetermined time interval is determined to be sufficiently long as to enable the video signal receiving apparatus 105 (in particular, the processor 107) to carry out the processing necessary to implement the switch between recording the broadcast video signal and recording the network video signal. However, the second predetermined time interval is also determined to be sufficiently short as to minimise any unnecessary delay between the occurrence of the advert initiation indicator 202B and the start of the ad break 201. The second predetermined time interval may be between 100 milliseconds (ms) and 2 seconds, for

example.

Because of the existence of the indicators 202A and 202B, it is possible for a user to implement an unauthorised operation to detect at least one of the indicators 202A and 202B in order to implement a so-called "ad skipping" function. Ad skipping involves temporarily suspending recording of the output video signal during the ad break 201 or marking start and end of the ad break 201 in the recorded output video signal so that, when the recorded video signal is played back, the TV program 200 is viewed without the ad break 201. It is possible when, for example, at least one of the indicators 202A and 202B is detectable by the unauthorised operation and the corresponding first and/or second predetermined time intervals and ad break duration is known. For example, if an unauthorised operation is able to detect the indicator 202A and it is known that the first predetermined time interval is 10 seconds, the second predetermined time interval is 1 second and that the ad break 201 lasts 3 minutes, the unauthorised operation knows that, upon detecting the indicator 202A, recording should be stopped (or an indicator indicating a start of a playback skipping operation should be added to the recorded video signal) in 11 seconds time and recording should be restarted (or an indicator indicating an end of the playback skipping operation should be added to the recorded video signal) in a further 3 minutes time. This is undesirable for the makers of the TV program 200 and the advertisers. Such an unauthorised operation may be implemented by unauthorised ad skipping software stored in the storage medium 109 by the user and executed by the processor 107, for example.

One way in which to reduce the risk of ad skipping is to encrypt each of the indicators 202A and 202B such that only an intended receiver of the video signal representative of the TV program is able to decrypt the indicators 202A and 202B. For example, the storage medium 109 may securely store a secret key for decrypting the indicators 202A and 202B which is only accessible by software implemented by the video signal receiving device 105 for performing the switching operation between the broadcast video signal and network video signal. An unauthorised operation cannot access the secret key and therefore cannot decrypt the indicators 202A and 202B in order to read them.

However, there is still a risk that an unauthorised operation is able to recognise the indicators 202A and 202B by, for example, detecting non-encrypted message headers of the indicators 202A and 202B or simply detecting the presence of an encrypted message and reasoning or deducing that it must be one of the indicators 202A and 202B. For example, if it is known that the indicator 202A is an encrypted message, that the first predetermined time interval is 10 seconds, that the second predetermined time interval is 1 second and that the ad break lasts 3 minutes, then it can be deduced, upon detection of an encrypted message video signal of the TV program, that the ad break 201 will start in 11 seconds time and last 3 minutes time. Ad skipping may therefore be carried out even though the encrypted indicator 202A cannot actually be read by the unauthorised ad skipping operation.

In order to alleviate the risk of the encrypted indicators 202A and 202B being recognised, in an embodiment, the indicator 202A is positioned in the broadcast video signal amongst one or more dummy advert retrieval indicators and the temporal position of the indicator 202A relative to those of the one or more dummy advert retrieval indicators is varied between different ad breaks 201. The indicator 202A is distinguishable amongst the one or more dummy indicators only by an intended receiver of the broadcast video signal.

For example, each of the indicator 202A and one or more dummy indicators may be encrypted and may be decryptable using a secret key securely stored in the storage medium 109 and accessible only by software implemented by the video signal receiving device 105 for performing the switching operation between the broadcast video signal and network video signal. The decrypted indicator 202A comprises data which distinguishes the indicator 202A from the one or more dummy indicators, thereby allowing the processor 107 to recognise the indicator 202A amongst the one or more dummy indicators.

In another example, each of the indicator 202A and one or more dummy indicators may be encrypted, but only the indicator 202A may be decryptable using the secret key securely stored in the storage medium 109 and accessible only by software implemented by the video signal receiving device 105 for performing the switching operation between the broadcast video signal and network video signal. The one or more dummy indicators are encrypted using a different key not known to the video signal receiving apparatus 105 (or any other apparatus other than the video signal transmitting apparatus 100). The processor 107 is thus able to recognise the indicator 202A amongst the one or more dummy indicators because it is the only one of the indicator 202A and one or more dummy indicators which can be successfully decrypted using the secret key stored in the storage medium 109. Successful decryption may be ascertained by the processor 107 finding, for example, a predetermined message or verifiable digital signature in the decrypted indicator 202A, or by the decrypted indicator 202A being the only one of the indicator 202A and one or more dummy indicators for which decryption is attempted which contains a coherent message understandable to the processor 107.

In either case, each of the one or more dummy indicators comprise different respective information so that the encrypted versions of the one or more dummy indicators all appear different (that is, each of the one or more dummy indicators 300 are distinguishable from each other). This prevents the indicator 202A from being recognised amongst the dummy indicators because it is the only one of the encrypted indicator 202A and dummy indicators which appears to be different from the others.

Similarly, the indicator 202B is positioned in the broadcast video signal amongst one or more dummy advert initiation indicators and the temporal position of the indicator 202B relative to those of the one or more dummy advert initiation indicators is varied between different ad breaks 201. The indicator 202B is distinguishable amongst the one or more dummy indicators only by an intended receiver of the broadcast video signal.

For example, each of the indicator 202B and one or more dummy indicators may be encrypted and may be decryptable using a secret key securely stored in the storage medium 109 and accessible only by software implemented by the video signal receiving device 105 for performing the switching operation between the broadcast video signal and network video signal. The decrypted indicator 202B comprises data which distinguishes the indicator 202B from the one or more dummy indicators, thereby allowing the processor 107 to recognise the indicator 202B amongst the one or more dummy indicators.

In another example, each of the indicator 202B and one or more dummy indicators may be encrypted, but only the indicator 202B may be decryptable using the secret key securely stored in the storage medium 109 and accessible only by software implemented by the video signal receiving device 105 for performing the switching operation between the broadcast video signal and network video signal. The one or more dummy indicators are encrypted using a different key not known to the video signal receiving apparatus 105 (or any other apparatus other than the video signal transmitting apparatus 100). The processor 107 is thus able to recognise the indicator 202B amongst the one or more dummy indicators because it is the only one of the indicator 202B and one or more dummy indicators which can be successfully decrypted using the secret key stored in the storage medium 109. Successful decryption may be ascertained by the processor 107 finding, for example, a predetermined message or verifiable digital signature in the decrypted indicator 202B, or by the decrypted indicator 202B being the only one of the indicator 202B and one or more dummy indicators for which decryption is attempted which contains a coherent message understandable to the processor 107.

In either case, each of the one or more dummy indicators comprise different respective information so that the encrypted versions of the one or more dummy indicators all appear different (that is, each of the one or more dummy indicators 301 are distinguishable from each other). This prevents the indicator 202B from being recognised amongst the dummy indicators because it is the only one of the encrypted indicator 202B and dummy indicators which appears to be different from the others.

In embodiments, the secret key and/or encryption / decryption method used to encrypt and decrypt the indicator 202A and/or one or more dummy advert retrieval indicators may be the same or different to the secret key and/or encryption / decryption method used to encrypt and decrypt the indicator 202B and/or one or more dummy advert initiation indicators.

In embodiments, each respective one of the indicator 202A and one or more dummy advert retrieval indicators is identical (e.g. comprises the same header and body comprising a string of alphanumeric characters output by an encryption algorithm) for each ad break. It is only the relative temporal positions of the indicator 202A and one or more dummy advert retrieval indicators which change for different ad breaks. Similarly, each respective one of the indicator 202B and one or more dummy advert initiation indicators is identical (e.g. comprises the same header and body comprising a string of alphanumeric characters output by an encryption algorithm) for each ad break. It is only the relative temporal positions of the indicator 202B and one or more dummy advert retrieval indicators which change for different ad breaks. Because of this, an entity which is not able to distinguish the indicator 202A or 202B from amongst its respective one or more dummy indicators simply sees the same set of different indicators occurring before each ad break (any of which could be the genuine indicator 202A or 202B) in an unpredictable order. This makes it very difficult to determine which indicator is the genuine indicator 202A or 202B, thereby making it difficult to successfully implement an ad skipping operation.

Figures 3A to 3C demonstrate the variation in the temporal positions of the indicators 202A and 202B relative to those of their respective dummy indicators for different ad breaks 201. The indicator 202A is variably positioned amongst 3 dummy advert retrieval indicators 300 so that there is a group of 4 indicators (one being the indicator 202A and the others being dummy indicators) temporally positioned one after the other. Similarly, the indicator 20213 is variable positioned amongst 3 dummy advert initiation indicators 301 so that there is a group of 4 indicators (one being the indicator 202B and the others being dummy indicators) temporally positioned one after the other. It will be appreciated, however, that different numbers of dummy advert retrieval and/or dummy advert initiation indicators may be used and that there may be the same or a different number of dummy advert retrieval indicators and dummy advert initiation indicators.

Figure 3A shows the temporal positions of the indicators 202A and 202B for a first ad break. Each of the indicators 202A and 202B is positioned as the 2nd indicator in its respective group of indicators (with the dummy indicators in each group being positioned at the 1st, 3rd and 4th positions). Figure 3B shows the temporal positions of the indicators 202A and 202B for a second ad break (e.g. occurring at a later time than the first ad break). This time, each of the indicators 202A and 202B is positioned as the 1st indicator in its respective group of indicators (with the dummy indicators of each group being repositioned at the 2nd, 3rd and 4th positions). Figure 3C shows the temporal positions of the indicators 202A and 202B for a third ad break (e.g. occurring at a later time than the first ad break). This time, each of the indicators 202A and 202B is positioned as the 4th indicator in its respective group of indicators (with the dummy indicators of each group being repositioned at the 1st, 2nd and 3ffi positions).

For ease of explanation, the ad break 201 is defined to be between the first part 200A and second part 20013 of the TV program 200 for each of Figures 3A to 3C. In reality, however, it will be appreciated that the first ad break will occur between first and second parts of the TV program, the second ad break will occur between second and third parts of the TV program and the third ad break will occur between third and fourth parts of the TV program. Also, for ease of explanation, the ad break 201 is shown to start at the same time for each of the Figures 3A to 3C. In reality, however, it will be appreciated that the ad break 201 may start at a different time for each of Figures 3A to 3C. For example, if the ad break 201 is initiated after a predetermined time interval following occurrence of the advert initiation indicator 202B (e.g. 1 second), then the ad break 201 will start at a different time depending on the position of the advert indication indicator 202B in its group of indicators (e.g. 1 second after the 2nd indicator in the group of indicators comprising the indicator 202B in Figure 3A, 1 second after the 2nd indicator in the group of indicators comprising the indicator 202B in Figure 3B and 1 second after the 4th indicator in the group of indicators comprising the indicator 202B in Figure 3C).

Because only the output video signal switching operation of the processor 107 is able to distinguish the indicator 202A from the dummy indicators 300, to any other operation (including an unauthorised ad skipper operation), the indicator 202A is not distinguishable from the dummy indicators 300. Similarly, because only the output video signal switching operation of the processor 107 is able to distinguish the indicator 202B from the dummy indicators 301, to any other operation (including an unauthorised ad skipper operation), the indicator 202B is not distinguishable from the dummy indicators 301. An ad skipper therefore cannot reliably determine when advert retrieval is instructed (since the advert retrieval indicator 202A could be any of the indicators 202A and 300) or when advert initiation is instructed (since the advert initiation indicator 202B could be any of the indicators 202B and 301). In turn, the ad skipper therefore cannot reliably determine when the ad break starts.

For example, even if it is known that the ad break always starts 11 seconds after the indicator 202A and 1 second after the indicator 202B, because the ad skipper is not able to reliably determine when either of the indicators 202A and 202B occurs, it cannot determine when it should start counting those 11 seconds or that 1 second in order to initiate the ad skip. The ad skip may simply take a guess of which of the indicators 202A and 300 is the true advert retrieval indicator 202A and/or which of the indicators 202B and 301 is the true advert initiation indicator 202B. However, if a pattern on the basis of which the temporal position of each of the indicators 202A and 202B is varied is not known to the ad skipper, then this guess will often be incorrect.

Ad skipping therefore carries a risk of skipping part of the TV program 200 itself, thereby discouraging the use of ad skipping.

In an embodiment, the temporal separation of adjacent indicators in each group (e.g. the group comprising the indicator 202A and dummy indicators 300 and the group comprising the indicator 202B and the dummy indicators 301) may be constant or may be different. The temporal separation value or range of values is chosen to be large enough to discourage the use of ad skipping (the greater the separation of adjacent indicators in a group, the more of the TV program 200 is skipped following an incorrect guess of the indicator 202A or indicator 202B) but small enough to enable sufficient granularity in the potential location of the indicators 202A and 202B (the smaller the separation of adjacent indicators in a group, the lower the total time duration of the group and thus the greater the number of potential insertion points of the group in the broadcast video signal).

The present technique therefore provides a technical solution for discouraging ad skipping in systems in which adverts are retrieved and initiated using advert retrieval indicators 202A and advert initiation indicators 202B.

The use of separate advert retrieval indicators 202A and advert initiation indicators 202B is beneficial over the use of a single indicator (in response to which adverts are both retrieved and initiated) for several reasons.

Because retrieval of the adverts is started (in response to detection of the advert retrieval indicator 202A) a certain amount of time before the adverts are played back (in response to detection of the advert initiation indicator 202B), the risk of an undesirable delay between the start of the ad break 201 and playback of the adverts (due to the need to buffer a portion of the electronic information representative of the adverts in the memory 108 prior to playing them back) is reduced. This is because the buffering of the adverts is able to take place during the certain amount of time between occurrence of the advert retrieval indicator 202A and the start of playback of the adverts.

Furthermore, because playback of the adverts retrieved in response to detection of the advert retrieval indicator 202A is not started until the detection of the advert initiation indicator 202B, there is improved flexibility as to when the ad break 201 containing the adverts is made to occur. This is particularly useful when the content within which the ad break 201 occurs relates to a live event, since occurrences during such live events cannot always be predicted in advance and therefore the most appropriate time in which to have the ad break 201 cannot always be predicted in advance. With the use of two separate advert retrieval and initiation indicators 202A and 202B, the advert retrieval can be started in advance (in response to the advert retrieval indicator 202A) and the advert playback can then be started without delay at a suitable time (e.g. during a break in play of a sporting event) by inserting the advert initiation indicator 202B in the broadcast video signal at that time.

Furthermore, because retrieval of the adverts is attempted in advance in response to detection of the advert retrieval indicator 202A, if there is a problem in retrieving the adverts (e.g. due to network connectivity problems or due to a fault with the server 113), then it is known before the ad break 201 occurs that retrieval of adverts over the network 112 has failed and that the ad break 201 should therefore comprise conventional broadcast adverts instead of adverts retrieved from the server 113. This decision can be made by the processor 107 prior to the ad break 201 occurring, thereby ensuring a transition from the TV program 200 due to the ad break 201 without delay even though adverts from the server 113 could not be received.

The use of separate retrieval indicators 202A and initiation indicators 202B thus provides the technical effect of improved flexibility and reduced delay when switching between different output video signals (in this example, when switching between an output video signal representative of a TV program 200 and an output video signal representative of one or more adverts 201A, 201B and 201C). However, the use of separate retrieval indicators 202A and initiation indicators 202B also results in a higher number of indicators being present (compared to if a single indicator is used to indicate both retrieval and initiation), thereby providing more events to analyse and learn from in order to perform unauthorised operations (such as ad skipping). The present technique alleviates this problem through the use of the dummy indicators 300 and 301, which make it difficult for the timing of the indicators 202A and 202B to be determined by an unauthorised operation and which thus make it difficult for such unauthorised operations to be carried out successfully.

Figures 4A to 4C show a variation of the present technique as exemplified in Figures 3A to 3C. In particular, in Figure 3A to 3C, the indicators 202A and 202B are positioned at the same position in their respective groups (that is, in Figure 3A, both indicators 202A and 202B are at the 2nd indicator position in their respective groups, in Figure 3B, both indicators 202A and 202B are at the 1st indicator position in their respective groups and, in Figure 3C, both indicators 202A and 202B are at the 4th indicator position in their respective groups). The temporal separation of the indicators 202A and 202B is therefore constant (e.g. 10 seconds). In Figures 4A to 4C, however, the indicators 202A and 202B may be positioned at different positions in their respective groups so that the temporal separation of the indicators 202A and 202B is variable between different ad breaks. This provides more flexibility in the position of each of the indicators 202A and 202B, thereby increasing the difficulty in predicting which indicators amongst the dummy indicators 300 and 301 are the indicators 202A and 202B.

In the example of Figures 4A to 4C, Figure 4A shows the temporal positions of the indicators 202A and 202B for a first ad break. The indicator 202A is positioned as the 2m indicator in its group of indicators whereas the indicator 202B is positioned as the 4th indicator in its group of indicators. Figure 3B shows the temporal positions of the indicators 202A and 202B for a second ad break (e.g. occurring at a later time than the first ad break). The indicator 202A is positioned as the 1st indicator in its group of indicators whereas the indicator 202B is positioned as the 2nd indicator in its group of indicators. Figure 3C shows the temporal positions of the indicators 202A and 202B for a third ad break (e.g. occurring at a later time than the first ad break). The indicator 202A is positioned as the 4th indicator in its group of indicators whereas the indicator 202B is positioned as the 1st indicator in its group of indicators. Again, for ease of explanation, the ad break 201 is defined to be between the first part 200A and second part 2008 of the TV program 200 for each of Figures 3A to 3C. In reality, however, it will be appreciated that the first ad break will occur between first and second parts of the TV program, the second ad break will occur between second and third parts of the TV program and the third ad break will occur between third and fourth parts of the TV program. All other features of Figures 4A to 4C are the same as those of Figures 3A to 3C.

In Figures 3A to 3C and Figures 4A to 4C, the position of the indicators 202A and 202B in their respective groups is determined in such a way as to be difficult to predict by an unauthorised operation attempting to implement ad skipping or similar. In one example, information indicative of a predetermined pattern known only to the video signal transmitting apparatus 100 (e.g. stored in the storage medium 104) is used to determine the position of the indicator 202A and/or the indicator 202B in their respective groups for different ad breaks 201. In Figures 3A to 3C, a single pattern is used to determine the position of both indicators 202A and 202B in their respective groups. On the other hand, in Figures 4A to 4C, two different patterns are used, respectively, to determine the position of the indicator 202A in its group and the position of the indicator 202B in its group.

In an example, each predetermined pattern takes the form of a predetermined list of numbers wherein each number in the list is between 1 and X, X being the number of indicators in each group (X=4 in Figures 3A to 3C and Figures 4A to 4C). Each number in the list then indicates the position of the indicator 202A and/or the indicator 202B for different respective ad breaks 201. For example, for Figures 3A to 3C, there is a single list [2, 1, 4], which results in the indicators 202A and 202B being positioned in the 2nd indicator position in Figure 3A, the 1st indicator position in Figure 3B and the 4th indicator position in Figure 3C. For Figures 4A to 4C, there are two lists. A first list [2, 1, 4] corresponding to the indicator 202A results in the indicator 202A being positioned in the 2nd indicator position in Figure 4A, the 1st indicator position in Figure 4B and the 4th indicator position in Figure 4C. A second list [4, 2, 1] corresponding to the indicator 202B results in the indicator 202B being positioned in the 4th indicator position in Figure 4A, the 2nd indicator position in Figure 4B and the 1st indicator position in Figure 4C. Each list may be repeated once the final number in the list has been used.

In an embodiment, each predetermined pattern is generated non-randomly (e.g. by selection of a set of numbers using a predetermined, non-random system known only to the operator of the video signal transmitting apparatus 100 which are then included in a number list). This helps prevent random noise filtering or the like from being used to determine which of the indicators in each group are the genuine indicators 202A and 202B. Such random noise filtering could potentially be used to identify the genuine indicators 202A and 202B if, for example, the position of the genuine indicators 202A and 202B in their respective groups is random but the position of the dummy indicators relative to each other in each group remains constant. This would be the case, for example, if there were three dummy advert retrieval indicators D1, D2 and D3 always presented in this temporal order and the genuine indicator 202A was randomly inserted before D1, between Oland D2, between D2 and D3 or after D3 for each ad break. There are advantages to keeping the dummy indicators in the same temporal order relative to each other (e.g. it is not necessary to randomise the dummy indicator order for each ad break, thereby reducing processing). By using a non-random generation of the pattern for determining the temporal position of the genuine indicators 202A and 202B, however, these advantages can be retained whilst also alleviating the risk of the genuine indicators 202A and 202B being identified based on random noise filtering.

In an embodiment, the number of common characteristics of successive groups of indicators may be reduced in order to make determination of the genuine indicator 202A or 202B by statistical analysis or the like more difficult (thereby making successful ad skipping more difficult). Two examples though which this is achieved are given below.

In a first example, the number of dummy indicators in each group may vary for different ad breaks. Thus, in the examples of Figures 3A to 3C or 4A to 4C, the number of dummy indicators in each group would not always be three, but would vary from ad break to ad break. For example, the variation may be based on another repeating predetermined pattern in the form of a numbered list (e.g. a numbered list [2, 6, 3] would result in two dummy indicators in the group for a first ad break, six dummy indicators in the group for a second ad break and three dummy indicators in the group for a third ad break). In this case, the previously mentioned predetermined pattern indicating the location of the genuine indicators 202A and 202B in their respective groups from ad break to ad break will take into account the number of dummy indicators in those groups for the ad break concerned (thereby avoiding the indication of a position of the genuine indicator 202A or 202B at a position which does not exist). For example, for the numbered list [X1, X2, X3] indicating the number of dummy indicators for three successive ad breaks, the numbered list indicating the position of the genuine indicator 202A or 202B [Y1, Y2, Y3] must satisfy Y1 X1 + 1, Y2 S X2 + 1 and Y3 S X3 + 1 (41" is necessary because the total number of indicators in each group is the number of dummy indicators X1, X2 or X3 plus the genuine indicator 202A or 202B). It will be appreciated that the varying number of dummy indicators may be the same for the group comprising the indicator 202A and the group comprising the indicator 202B for each ad break or may be different (in which case, each group will have a different respective predetermined pattern indicating the number of dummy indicators of that group and a different respective pattern indicating the position of the genuine indicator 202A or 202B of that group). It will also be appreciated that the number of dummy indicators may be varied for only one of the group comprising the indicator 202A and the group comprising the indicator 202B.

In a second example (which may or may not be implemented together with the first example), one or more of the dummy indicators in a group is duplicated within the group (so that there are two or more identical instances of that dummy indicator in the group) and the group also comprises one or more duplicates of the genuine indicator 202A or 202B (i.e. so that there are two or more identical instances of that genuine indicator in the group). In this case, for example, the processor 107 performs the switching operating in response to detection of the first instance of the genuine indicator 202A or 202B in the group concerned and ignores any subsequent duplicate instances of the genuine indicator 202A or 202B in that group. On the other hand, an unauthorised operation will see the duplications of both the one or more dummy indicators and the genuine indicator (which it is not able to distinguish between). This makes it difficult to try to determine the genuine indicator based on which indicators are repeated within a group and which are not. The number and location of the genuine indicator duplicate(s) for successive ad breaks may again be based on a predetermined pattern in the form of a numbered list (which may apply to both the group comprising the genuine indicator 202A and the group comprising the genuine indicator 202B or to just one of these groups). In a variation on this example (e.g. in which none of the dummy indicators in a group are duplicated within that group), a group may contain a plurality of genuine indicators 202A or 202B, each of which cause the processor 107 to perform the switching operation (when detected as the first genuine indicator in the group) but which contain different information and so appear different. For example, there may be several different genuine indicators 202A or 202B each of which, once decrypted with the secret key, indicate to the processor that they are genuine (e.g. a first retrieval indicator is decrypted to provide a message "A" and a second retrieval indicator is decrypted to provide a message "B", but the processor 107 knows that both "A" and "B" indicate a genuine retrieval indicator 202A). Figure 5A shows a process carried out by the video signal receiving apparatus 105, according to an embodiment.

The process starts at step 501.

At step 502, a first video signal (e.g. representative of the TV program 200) is received (e.g. by the RF receiver 106).

At step 503, the processor 107 identifies, in the first video signal, a second video signal retrieval indicator (e.g. advert retrieval indicator 202A). The second video signal retrieval indicator is variably positioned relative to the positions of one or more dummy second video signal retrieval indicators (e.g. dummy advert retrieval indicators 300) in the first video signal and is identifiable using a characteristic (e.g. a predetermined characteristic) of the second video signal retrieval indicator which distinguishes the second video signal retrieval indicator from the one or more dummy second video signal retrieval indicators. The characteristic of the second video signal retrieval indicator is known to an intended receiver of the second video signal retrieval indicator. The characteristic is, for example, data included in the second video signal retrieval indicator which is decryptable only by an intended receiver of the second video signal retrieval indicator (e.g. using a secret key stored in the storage medium 109) or, for example, the fact that the second video signal retrieval indicator is decryptable by that intended receiver in the first place (e.g. using a secret key stored in the storage medium 109).

At step 504, a second video signal (e.g. adverts 201A, 201B and 201C) is retrieved in response to identifying the second video signal retrieval indicator.

At step 505, the processor 107 identifies, in the first video signal, a second video signal initiation indicator (e.g. advert initiation indicator 202B). The second video signal initiation indicator is variably positioned relative to the positions of one or more dummy second video signal initiation indicators (e.g. dummy advert initiation indicators 301) in the first video signal and is identifiable using a characteristic (e.g. a predetermined characteristic) of the second video signal initiation indicator which distinguishes the second video signal retrieval indicator from the one or more dummy second video signal initiation indicators. The characteristic of the second video signal initiation indicator is known to an intended receiver of the second video signal initiation indicator. The characteristic is, for example, data included in the second video signal initiation indicator which is decryptable only by an intended receiver of the second video signal initiation indicator (e.g. using a secret key stored in the storage medium 109) or, for example, the fact that the second video signal initiation indicator is decryptable by that intended receiver in the first place (e.g. using a secret key stored in the storage medium 109).

At step 506, the output 111 outputs the second video signal (e.g. to the display device 114 or video recording medium 115) in response to identifying the second video signal initiation indicator.

The process then ends at step 507.

It will be appreciated that a computer program (e.g. in the form of a software application (app) such as a TV or STB app) may be transmitted to the video signal receiving apparatus 105 in order to control the video signal receiving apparatus to carry out at least steps 503, 504, 505 and 506 of the method of Figure 5A. Such a computer program may be transmitted by the server 113, for example.

Figure 5B shows a process carried out by the video signal transmitting apparatus 100, according to an embodiment.

The process starts at step 508.

At step 509, the first video signal (e.g. representative of the TV program 200) is transmitted (e.g. by the RF transmitter 1010). The first video signal comprises the second video signal retrieval indicator (e.g. advert retrieval indicator 202A) which is variably positionable relative to the positions of the one or more dummy second video signal retrieval indicators (e.g. dummy advert retrieval indicators 300) by the processor 102. The first video signal also comprises, at a later time, the second video signal initiation indicator (e.g. advert initiation indicator 202B) which is variably positionable relative to the positions of the one or more dummy second video signal initiation indicators (e.g. dummy advert initiation indicators 301) by the processor 102.

The process then ends at step 510.

Some embodiments of the present technique are defined by the following numbered clauses: 1. A video signal receiving apparatus comprising processor circuitry, input circuitry and output circuitry, the processor circuitry being configured to: control the input circuitry configured to receive a first video signal; and identify, in the first video signal, a second video signal retrieval indicator variably positioned relative to the positions of one or more dummy second video signal retrieval indicators in the first video signal using a characteristic of the second video signal retrieval indicator which distinguishes the second video signal retrieval indicator from the one or more dummy second video signal retrieval indicators, the characteristic of the second video signal retrieval indicator being known to an intended receiver of the second video signal retrieval indicator; retrieve a second video signal in response to identifying the second video signal retrieval indicator; identify, in the first video signal, a second video signal initiation indicator variably positioned relative to the positions of one or more dummy second video signal initiation indicators in the first video signal using a characteristic of the second video signal initiation indicator which distinguishes the second video signal retrieval indicator from the one or more dummy second video signal initiation indicators, the characteristic of the second video signal initiation indicator being known to an intended receiver of the second video signal initiation indicator; and control the output circuitry to output the second video signal in response to identifying the second video signal initiation indicator.

2. A video signal receiving apparatus according to clause 1, wherein the processor circuitry is configured: to control the output circuitry to output the first video signal; in response to identifying the second video signal initiation indicator, to control the output circuitry to output the second video signal in place of the first video signal; and after output of the second video signal is completed, to control the output circuitry to return to outputting the first video signal.

3. A video signal receiving apparatus according to clause 2, wherein the first and second video signals are output for storage as a file in a storage medium.

4. A video signal receiving apparatus according to any preceding clause, wherein a temporal separation between the second video signal retrieval indicator and the second video signal initiation indicator is variable.

5. A video signal receiving apparatus according to any preceding clause, wherein the first video signal is a broadcasted radio signal.

6. A video signal receiving apparatus according to any preceding clause, wherein the second video signal is retrieved over a computer network.

7. A video signal receiving apparatus according to any preceding clause, wherein: the second video signal retrieval indicator is encrypted and is decryptable using a first decryption key known to an intended receiver of the second video signal retrieval indicator; 15 and/or the second video signal initiation indicator is encrypted and is decryptable using a second decryption key known to an intended receiver of the second video signal initiation indicator.

8. A video signal receiving apparatus according to clause 7, wherein: none of the one or more dummy second video signal retrieval indicators are decryptable using the first decryption key and the processor circuitry is configured to identify the second video signal retrieval indicator from the one or more dummy second video signal retrieval indicators by attempting to decrypt each of the second video signal retrieval indicator and one or more dummy second video signal retrieval indicators using the first decryption key; and/or none of the one or more dummy second video signal initiation indicators are decryptable using the second decryption key and the processor circuitry is configured to identify the second video signal initiation indicator from the one or more dummy second video signal initiation indicators by attempting to decrypt each of the second video signal initiation indicator and one or more dummy second video signal initiation indicators using the second decryption key.

9. A video signal receiving apparatus according to clause 7, wherein: the decrypted second video signal retrieval indicator comprises data which distinguishes the second video signal retrieval indicator from the one or more dummy second video signal retrieval indicators; and/or the decrypted second video signal initiation indicator comprises data which distinguishes the second video signal initiation indicator from the one or more dummy second video signal initiation indicators.

10. A video signal receiving apparatus according to any preceding clause, wherein each of the one or more dummy second video signal retrieval indicators are distinguishable from each other and each of the one or more dummy second video signal initiation indicators are distinguishable from each other.

11. A video signal receiving apparatus according to any preceding clause. wherein the first video signal corresponds to content and the second video signal corresponds to an advertisement.

12. A video signal transmitting apparatus comprising transmitter circuitry configured to transmit a first video signal, the first video signal comprising: a second video signal retrieval indicator variably positionable relative to the positions of one or more dummy second video signal retrieval indicators in the first video signal, the second video signal retrieval indicator being distinguishable from the one or more dummy second video signal retrieval indicators using a characteristic of the second video signal retrieval indicator known to an intended receiver of the second video signal retrieval indicator so that the intended receiver is able to retrieve a second video signal in response to identifying the second video signal retrieval indicator; a second video signal initiation indicator variably positionable relative to the positions of one or more dummy second video signal initiation indicators in the first video signal, the second video signal initiation indicator being distinguishable from the one or more dummy second video signal initiation indicators using a characteristic of the second video signal initiation indicator known to an intended receiver of the second video signal initiation indicator so that the intended receiver is able to output the second video signal in response to identifying the second video signal initiation indicator.

13. A video signal transmitting apparatus according to clause 12, wherein a temporal separation between the second video signal retrieval indicator and the second video signal initiation indicator is variable.

14. A video signal transmitting apparatus according to clause 12 or 13, wherein the first video signal is a broadcasted radio signal.

15. A video signal transmitting apparatus according to any one of clauses 12 to 14, wherein the second video signal is retrieved by the intended receiver over a computer network.

16. A video signal transmitting apparatus according to any one of clauses 12 to 15, wherein: the second video signal retrieval indicator is encrypted and is decryptable using a first decryption key known to an intended receiver of the second video signal retrieval indicator; and/or the second video signal initiation indicator is encrypted and is decryptable using a second decryption key known to an intended receiver of the second video signal initiation indicator.

17. A video signal transmitting apparatus according to clause 16, wherein: none of the one or more dummy second video signal retrieval indicators are decryptable using the first decryption key and the second video signal retrieval indicator is identifiable from the one or more dummy second video signal retrieval indicators by the intended receiver attempting to decrypt each of the second video signal retrieval indicator and one or more dummy second video signal retrieval indicators using the first decryption key; and/or none of the one or more dummy second video signal initiation indicators are decryptable using the second decryption key and the second video signal initiation indicator is identifiable from the one or more dummy second video signal initiation indicators by the intended receiver attempting to decrypt each of the second video signal initiation indicator and one or more dummy second video signal initiation indicators using the second decryption key.

18. A video signal transmitting apparatus according to clause 16, wherein: the decrypted second video signal retrieval indicator comprises data which distinguishes the second video signal retrieval indicator from the one or more dummy second video signal retrieval indicators; and/or the decrypted second video signal initiation indicator comprises data which distinguishes the second video signal initiation indicator from the one or more dummy second video signal initiation indicators.

19. A video signal transmitting apparatus according to any one of clauses 12 to 18, wherein each of the one or more dummy second video signal retrieval indicators are distinguishable from each other and each of the one or more dummy second video signal initiation indicators are distinguishable from each other.

20. A video signal transmitting apparatus according to any one of clauses 12 to 19, wherein the first video signal corresponds to content and the second video signal corresponds to an advertisement.

21. A video signal receiving method, comprising: receiving a first video signal; and identifying, in the first video signal, a second video signal retrieval indicator variably positioned relative to the positions of one or more dummy second video signal retrieval indicators in the first video signal using a characteristic of the second video signal retrieval indicator which distinguishes the second video signal retrieval indicator from the one or more dummy second video signal retrieval indicators, the characteristic of the second video signal retrieval indicator being known to an intended receiver of the second video signal retrieval indicator; retrieving a second video signal in response to identifying the second video signal retrieval indicator; identifying, in the first video signal, a second video signal initiation indicator variably positioned relative to the positions of one or more dummy second video signal initiation indicators in the first video signal using a characteristic of the second video signal initiation indicator which distinguishes the second video signal retrieval indicator from the one or more dummy second video signal initiation indicators, the characteristic of the second video signal initiation indicator being known to an intended receiver of the second video signal initiation indicator; and outputting the second video signal in response to identifying the second video signal initiation indicator.

22. A video signal transmitting method comprising transmitting a first video signal, the first video signal comprising: a second video signal retrieval indicator variably positionable relative to the positions of one or more dummy second video signal retrieval indicators in the first video signal, the second video signal retrieval indicator being distinguishable from the one or more dummy second video signal retrieval indicators using a characteristic of the second video signal retrieval indicator known to an intended receiver of the second video signal retrieval indicator so that the intended receiver is able to retrieve a second video signal in response to identifying the second video signal retrieval indicator; a second video signal initiation indicator variably positionable relative to the positions of one or more dummy second video signal initiation indicators in the first video signal, the second video signal initiation indicator being distinguishable from the one or more dummy second video signal initiation indicators using a characteristic of the second video signal initiation indicator known to an intended receiver of the second video signal initiation indicator so that the intended receiver is able to output the second video signal in response to identifying the second video signal initiation indicator.

23. A program for controlling a computer to perform a method according to clause 21 or 22.

24. A storage medium storing a program according to clause 23.

25. A server apparatus configured to transmit, to a video signal receiving apparatus, a program for controlling the video signal receiving apparatus to: identify, in a first video signal received by the video signal receiving apparatus, a second video signal retrieval indicator variably positioned relative to the positions of one or more dummy second video signal retrieval indicators in the first video signal using a characteristic of the second video signal retrieval indicator which distinguishes the second video signal retrieval indicator from the one or more dummy second video signal retrieval indicators, the characteristic of the second video signal retrieval indicator being known to an intended receiver of the second video signal retrieval indicator; retrieve a second video signal in response to identifying the second video signal retrieval indicator; identify, in the first video signal, a second video signal initiation indicator variably positioned relative to the positions of one or more dummy second video signal initiation indicators in the first video signal using a characteristic of the second video signal initiation indicator which distinguishes the second video signal retrieval indicator from the one or more dummy second video signal initiation indicators, the characteristic of the second video signal initiation indicator being known to an intended receiver of the second video signal initiation indicator; and output the second video signal in response to identifying the second video signal initiation indicator.

Numerous modifications and variations of the present disclosure are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the disclosure may be practiced otherwise than as specifically described herein.

In so far as embodiments of the disclosure have been described as being implemented, at least in part, by software-controlled data processing apparatus, it will be appreciated that a non-transitory machine-readable medium carrying such software, such as an optical disk, a magnetic disk, semiconductor memory or the like, is also considered to represent an embodiment of the present disclosure.

It will be appreciated that the above description for clarity has described embodiments with reference to different functional units, circuitry and/or processors. However, it will be apparent that any suitable distribution of functionality between different functional units, circuitry and/or processors may be used without detracting from the embodiments.

Described embodiments may be implemented in any suitable form including hardware, software, firmware or any combination of these. Described embodiments may optionally be implemented at least partly as computer software running on one or more data processors and/or digital signal processors. The elements and components of any embodiment may be physically, functionally and logically implemented in any suitable way. Indeed the functionality may be implemented in a single unit, in a plurality of units or as part of other functional units. As such, the disclosed embodiments may be implemented in a single unit or may be physically and functionally distributed between different units, circuitry and/or processors.

Although the present disclosure has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Additionally, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognize that various features of the described embodiments may be combined in any manner suitable to implement the technique.

Claims

CLAIMS1. A video signal receiving apparatus comprising processor circuitry, input circuitry and output circuitry, the processor circuitry being configured to: control the input circuitry configured to receive a first video signal; and identify, in the first video signal, a second video signal retrieval indicator variably positioned relative to the positions of one or more dummy second video signal retrieval indicators in the first video signal using a characteristic of the second video signal retrieval indicator which distinguishes the second video signal retrieval indicator from the one or more dummy second video signal retrieval indicators, the characteristic of the second video signal retrieval indicator being known to an intended receiver of the second video signal retrieval indicator; retrieve a second video signal in response to identifying the second video signal retrieval indicator; identify, in the first video signal, a second video signal initiation indicator variably positioned relative to the positions of one or more dummy second video signal initiation indicators in the first video signal using a characteristic of the second video signal initiation indicator which distinguishes the second video signal retrieval indicator from the one or more dummy second video signal initiation indicators, the characteristic of the second video signal initiation indicator being known to an intended receiver of the second video signal initiation indicator; and control the output circuitry to output the second video signal in response to identifying the second video signal initiation indicator.
2. A video signal receiving apparatus according to claim 1, wherein the processor circuitry is configured: to control the output circuitry to output the first video signal; in response to identifying the second video signal initiation indicator, to control the output circuitry to output the second video signal in place of the first video signal; and after output of the second video signal is completed, to control the output circuitry to return to outputting the first video signal.
3. A video signal receiving apparatus according to claim 2, wherein the first and second video signals are output for storage as a file in a storage medium.
4. A video signal receiving apparatus according to claim 1, wherein a temporal separation between the second video signal retrieval indicator and the second video signal initiation indicator is variable.
5. A video signal receiving apparatus according to claim 1, wherein the first video signal is a broadcasted radio signal.
6. A video signal receiving apparatus according to claim 1, wherein the second video signal is retrieved over a computer network. 10
7. A video signal receiving apparatus according to claim 1, wherein: the second video signal retrieval indicator is encrypted and is decryptable using a first decryption key known to an intended receiver of the second video signal retrieval indicator; and/or the second video signal initiation indicator is encrypted and is decryptable using a second decryption key known to an intended receiver of the second video signal initiation indicator.
8. A video signal receiving apparatus according to claim 7, wherein: none of the one or more dummy second video signal retrieval indicators are decryptable using the first decryption key and the processor circuitry is configured to identify the second video signal retrieval indicator from the one or more dummy second video signal retrieval indicators by attempting to decrypt each of the second video signal retrieval indicator and one or more dummy second video signal retrieval indicators using the first decryption key; and/or none of the one or more dummy second video signal initiation indicators are decryptable using the second decryption key and the processor circuitry is configured to identify the second video signal initiation indicator from the one or more dummy second video signal initiation indicators by attempting to decrypt each of the second video signal initiation indicator and one or more dummy second video signal initiation indicators using the second decryption key.
9. A video signal receiving apparatus according to claim 7, wherein: the decrypted second video signal retrieval indicator comprises data which distinguishes the second video signal retrieval indicator from the one or more dummy second video signal retrieval indicators; and/or the decrypted second video signal initiation indicator comprises data which distinguishes the second video signal initiation indicator from the one or more dummy second video signal initiation indicators.
10. A video signal receiving apparatus according to claim 1, wherein each of the one or more dummy second video signal retrieval indicators are distinguishable from each other and each of the one or more dummy second video signal initiation indicators are distinguishable from each other.
11. A video signal receiving apparatus according to claim 1, wherein the first video signal corresponds to content and the second video signal corresponds to an advertisement.
12. A video signal transmitting apparatus comprising transmitter circuitry configured to transmit a first video signal, the first video signal comprising: a second video signal retrieval indicator variably positionable relative to the positions of one or more dummy second video signal retrieval indicators in the first video signal, the second video signal retrieval indicator being distinguishable from the one or more dummy second video signal retrieval indicators using a characteristic of the second video signal retrieval indicator known to an intended receiver of the second video signal retrieval indicator so that the intended receiver is able to retrieve a second video signal in response to identifying the second video signal retrieval indicator; a second video signal initiation indicator variably positionable relative to the positions of one or more dummy second video signal initiation indicators in the first video signal, the second video signal initiation indicator being distinguishable from the one or more dummy second video signal initiation indicators using a characteristic of the second video signal initiation indicator known to an intended receiver of the second video signal initiation indicator so that the intended receiver is able to output the second video signal in response to identifying the second video signal initiation indicator.
13. A video signal transmitting apparatus according to claim 12, wherein a temporal separation between the second video signal retrieval indicator and the second video signal initiation indicator is variable.
14. A video signal transmitting apparatus according to claim 12, wherein the first video signal is a broadcasted radio signal.
15. A video signal transmitting apparatus according to claim 12, wherein the second video signal is retrieved by the intended receiver over a computer network.
16. A video signal transmitting apparatus according to claim 12, wherein: the second video signal retrieval indicator is encrypted and is decryptable using a first decryption key known to an intended receiver of the second video signal retrieval indicator; and/or the second video signal initiation indicator is encrypted and is decryptable using a second decryption key known to an intended receiver of the second video signal initiation indicator.
17. A video signal transmitting apparatus according to claim 16, wherein: none of the one or more dummy second video signal retrieval indicators are decryptable using the first decryption key and the second video signal retrieval indicator is identifiable from the one or more dummy second video signal retrieval indicators by the intended receiver attempting to decrypt each of the second video signal retrieval indicator and one or more dummy second video signal retrieval indicators using the first decryption key; and/or none of the one or more dummy second video signal initiation indicators are decryptable using the second decryption key and the second video signal initiation indicator is identifiable from the one or more dummy second video signal initiation indicators by the intended receiver attempting to decrypt each of the second video signal initiation indicator and one or more dummy second video signal initiation indicators using the second decryption key.
18. A video signal transmitting apparatus according to claim 16, wherein: the decrypted second video signal retrieval indicator comprises data which distinguishes the second video signal retrieval indicator from the one or more dummy second video signal retrieval indicators; and/or the decrypted second video signal initiation indicator comprises data which distinguishes the second video signal initiation indicator from the one or more dummy second video signal initiation indicators.
19. A video signal transmitting apparatus according to claim 12, wherein each of the one or more dummy second video signal retrieval indicators are distinguishable from each other and each of the one or more dummy second video signal initiation indicators are distinguishable from each other.
20. A video signal transmitting apparatus according to claim 12, wherein the first video signal corresponds to content and the second video signal corresponds to an advertisement.
21. A video signal receiving method, comprising: receiving a first video signal; and identifying, in the first video signal, a second video signal retrieval indicator variably positioned relative to the positions of one or more dummy second video signal retrieval indicators in the first video signal using a characteristic of the second video signal retrieval indicator which distinguishes the second video signal retrieval indicator from the one or more dummy second video signal retrieval indicators, the characteristic of the second video signal retrieval indicator being known to an intended receiver of the second video signal retrieval indicator; retrieving a second video signal in response to identifying the second video signal retrieval indicator; identifying, in the first video signal, a second video signal initiation indicator variably positioned relative to the positions of one or more dummy second video signal initiation indicators in the first video signal using a characteristic of the second video signal initiation indicator which distinguishes the second video signal retrieval indicator from the one or more dummy second video signal initiation indicators, the characteristic of the second video signal initiation indicator being known to an intended receiver of the second video signal initiation indicator; and outputting the second video signal in response to identifying the second video signal initiation indicator.
22. A video signal transmitting method comprising transmitting a first video signal, the first video signal comprising: a second video signal retrieval indicator variably positionable relative to the positions of one or more dummy second video signal retrieval indicators in the first video signal, the second video signal retrieval indicator being distinguishable from the one or more dummy second video signal retrieval indicators using a characteristic of the second video signal retrieval indicator known to an intended receiver of the second video signal retrieval indicator so that the intended receiver is able to retrieve a second video signal in response to identifying the second video signal retrieval indicator; a second video signal initiation indicator variably positionable relative to the positions of one or more dummy second video signal initiation indicators in the first video signal, the second video signal initiation indicator being distinguishable from the one or more dummy second video signal initiation indicators using a characteristic of the second video signal initiation indicator known to an intended receiver of the second video signal initiation indicator so that the intended receiver is able to output the second video signal in response to identifying the second video signal initiation indicator.
23. A program for controlling a computer to perform a method according to claim 21 or 22.
24. A storage medium storing a program according to claim 23.
25. A server apparatus configured to transmit, to a video signal receiving apparatus, a program for controlling the video signal receiving apparatus to: identify, in a first video signal received by the video signal receiving apparatus, a second video signal retrieval indicator variably positioned relative to the positions of one or more dummy second video signal retrieval indicators in the first video signal using a characteristic of the second video signal retrieval indicator which distinguishes the second video signal retrieval indicator from the one or more dummy second video signal retrieval indicators, the characteristic of the second video signal retrieval indicator being known to an intended receiver of the second video signal retrieval indicator; retrieve a second video signal in response to identifying the second video signal retrieval indicator; identify, in the first video signal, a second video signal initiation indicator variably positioned relative to the positions of one or more dummy second video signal initiation indicators in the first video signal using a characteristic of the second video signal initiation indicator which distinguishes the second video signal retrieval indicator from the one or more dummy second video signal initiation indicators, the characteristic of the second video signal initiation indicator being known to an intended receiver of the second video signal initiation indicator; and output the second video signal in response to identifying the second video signal initiation indicator.