Defeat method and apparatus for content management for high definition television
A high definition television video content management and/or copy protection method and apparatus are achieved by modifying portions of one or more channels of an HDTV (high definition television) signal. These modifications are generally in the blanking intervals but can extend into the overscanned portions. In one version, the signal modification defines tags or trigger bits for a content control system. This modification may follow the HDTV tri-level sync (synchronization) pulses for example, and it may occur in at least one of the HDTV video channels. In another version, portions of the tri-level sync pulse are modified to cause a reference sensing circuit such an AGC system (in a receiving device such as a video recorder) to produce an erroneous output. Optionally, a signal may be added or inserted following the modified tri-level sync pulses. In another version, tri-level pseudo sync pulses are added in blanking or overscanned intervals. These tri-level pseudo sync pulses may be asymmetrical and may be followed by a signal. Further, any of the above modifications or signals or sync signals may be modulated (e.g., amplitude, position, pulse-width). Also provided are defeat methods and associated apparatus to reduce effects or to modify video signals resulting from the modification processes. The defeat methods include modifying a portion of the video signal associated with the tri-level synchronization pluses so as to allow subsequent recording of the modified video signal or to alter the information in the modified video signal pertaining to the content management such as the tags or trigger bits.
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This application claims priority to U.S. provisional application 60/623,297 filed Oct. 28, 2004, and relates to commonly invented U.S. application titled “Content Management for High Definition Television”, which is being filed concurrently.
FIELD OF THE INVENTIONThis disclosure relates to video and more specifically to high definition television and more specifically to content management for high definition television, including copy control.
BACKGROUNDHigh definition television (HDTV) is now being introduced commercially in the U.S. Many U.S. television stations broadcast high definition television programs, and HDTV receiving equipment is available to the consumer. HDTV is a type of digital television (DTV). This means that the signals are transmitted generally in digital format, requiring special receivers. Two HDTV formats, approved in the United States, referred to as 1080i and 720p. The 1080i refers to a television picture with 1,080 video scan lines each with 1,920 pixels horizontally. The i refers to interlace scanning as used in traditional analog (NTSC, PAL, SEC AM) television which alternates sending odd lines and even lines in each frame to form a field. The 720p format provides a pictures with 720 vertical lines each with 1,280 pixels horizontally. The p refers to progressive scanning as used in computer displays. HDTV is replacing standard analog (NTSC, in the U.S.) television. HDTV is also being introduced outside the United States although similar to the case with analog television, somewhat different HDTV formats are being adapted by different countries and groups of countries, e.g., using different frame rates. Digital TV here refers to particular television formats and is not the same as so-called digital cable television. Digital TV (in this sense, actually digital broadcast television) actually defines (in the U.S.) eighteen different formats for broadcast television in a digital format. HDTV is six of those eighteen formats. The U.S. Federal Communications Commission (FCC) has ordered that by May 2006 all U.S. broadcasters will broadcast digital television signals in place of analog television signals.
As well known, in analog (e.g. NTSC) television, each video (horizontal) scan line includes a horizontal blanking interval including what is called a horizontal synchronization (sync) pulse. In between the horizontal blanking intervals there occurs what is called the active video. The end of each field of video also includes a vertical blanking interval. The blanking intervals are used to provide timing signals for the picture and operation of the receiver. The well known horizontal synchronization pulse in analog television includes what is called a front porch immediately preceding the horizontal sync pulse and a back porch immediately following the horizontal sync pulse. In analog television such as NTSC, PAL, and SECAM television the horizontal back porch also contains the color burst which is a color timing reference signal.
The vertical blanking regions are considerably longer than the horizontal blanking intervals in analog television and extend over, in terms of duration, the equivalent of a number of horizontal scan lines. The vertical blanking interval includes a relatively long vertical synchronization pulse followed by a number of so called equalizing pulses. In analog television, the horizontal sync pulse includes only two levels, one of which corresponds to a zero amplitude pulse or a blanking level and the other which is a lower amplitude pulse which is at sync tip level. However, for HDTV there has been defined an additional third level of the sync pulse, thus providing what is called a tri-level horizontal sync pulse. This includes initially a low negative going pulse (e.g. a sync tip level), followed immediately by a high positive going pulse, which crosses a blanking level. Thus the three levels provided are low, high and blanking level. The positive going pulse in a tri-level sync pulse is higher than the blanking level. Hence the use of tri-level sync pulses is conventional in HDTV as defined in the United States and also as used in other countries. Note that the HDTV typically includes three channels and hence is a type of composite video. These channels, for example, are referred to as Y (luma), Pb and Pr (chroma) which are the chroma channels. The Y (luma) channel is also sometimes referred to as the green channel with Pb sometimes referred to as a blue channel and Pr as a red channel. Of course other types of multiple channel video systems can be used.
Note that while the signal transmission in HDTV is digital, actually a significant portion of the signal processing takes place effectively in the analog domain and hence it is conventional to draw waveforms of the video signal for HDTV which look essentially the same as the analog type waveforms drawn to represent analog television signals. That convention is followed here.
One exemplary tri-level sync pulse used in HDTV has the blanking level at zero volts, the negative going portion at −0.3 volts and the positive going portion at +0.3 volts, followed by a back porch region and then followed by the active video portion. Just as in analog television, this tri-level horizontal sync pulse is repeated every scan line to create an entire high definition video frame. Synchronization and loss of synchronization otherwise may operate somewhat differently in high HDTV than in analog television. For analog television, loss of synchronization causes the image to roll and distort on the screen as the TV set tries to relock back into sync. However, high definition television receivers, being essentially digital devices, may have a different operation. On the screen, when sync is lost, in one example, there is likely to be displayed a green flash in the image or a series of green frames for ongoing loss of synchronization. In another example, a loss of sync in an HDTV signal may cause the display to blank out.
Also well known in the field of analog video and television is what is generally referred to as content management, an aspect of which is copy protection. Examples of copy protection are disclosed in Ryan U.S. Pat. No. 4,631,603 and Ryan U.S. Pat. No. 4,577,216 both incorporated herein by reference in their entireties. Generally these describe methods and apparatus for processing a video signal to inhibit making of acceptable video recordings therefrom. It is also known to defeat these copy protection processes, see for instance Ryan U.S. Pat. No. 4,695,901 also incorporated by reference herein in its entirety. Another method of inhibiting making of acceptable video recordings is disclosed in Ryan U.S. Pat. No. 4,819,098 using clustering modifications to a video signal. Generally these copy protection techniques and apparatus modify an otherwise standard video signal in such a way that the resulting video signal, while readily displayed on a display device (a TV set or monitor) when provided to a video recorder such as a video tape recorder, produce distortion on any copies made therefrom by the recorder, thus resulting in an unacceptable copy in terms of later viewing. Copy protection in this context includes a technical means for making copies unviewable or less viewable on a conventional display device when using a conventional recording device to make the copies.
The broader field of content management also includes so-called compliant devices which are designed so that they include circuitry that detects for certain signals or the absence of same in a video signal being received. The presence (or absence) of the particular signal acts as a command to the receiving device thereby to enable or inhibit recording. In some cases, this involves generational copy management whereby a first generation copy may be made, but subsequent generation copies are prevented. See for instance Talstra et al. U.S. Pat. No. 6,701,062 disclosing such a system for video as provided on a media such as a DVD. Such copy management is applicable to a digital video signal of the type used on video media such as DVDs. These more sophisticated copy control systems typically require dedicated circuitry and/or software in the receiving device to detect and interpret the special data provided in the video signal for purposes of content management.
However, none of these methods are directed to HDTV or, for that matter, to digital broadcast television generally. In this context, of course, broadcast includes not only conventional broadcast, but also cable, satellite broadcast, etc. None of these methods address the particular configuration of HDTV video signals or the differences of HDTV from, for instance, analog television signals.
SUMMARYIn one embodiment, tag signals or trigger bits are added or inserted following at least a tri-level sync pulse in HDTV video for purposes of content control or copy protection. For example in one of the HDTV video channels such as the luma (Y) channel, a selected number of pulses are added to the vertical blanking interval to define commands to a compliant device for purposes of content control. Moreover, a selected number of pulses in another video channel such as the chroma (Pb and/or Pr) channels may also carry information (commands) for content control.
A typical added signal here may be at least one pulse. For example, in the Y channel the added signal may be a positive going pulse located in the tri-level sync pulse front and/or back porch region(s). For example, in the Pb or Pr channel(s), the added signal may include a positive and/or negative pulse. Most notably, in the Pb or Pr channels, the blanking level is at 50% of the maximum voltage range (versus 0% in the Y channel), so the front and/or back porch regions can carry positive or negative pulses. Also, the added signal may include a burst of cycles. Depending on the number of cycles, their phase, duration, and/or frequency, content control information is conveyed.
The above signals and pulses may be further modulated. Such modulation may also be part of a method for content control by carrying information defining the commands for purposes of content control. The commands are interpreted (decoded) by suitable circuitry and/or software in a compliant device, e.g., a video recorder, to control subsequent use of the video content. An example of content control is the addition of a set of “pseudo” (e.g., not located according to the HDTV standard) tri-level sync pulses that, when received by a compliant (specially adapted) video recorder, command the video recorder not to record the accompanying video. Another example of content control is the well known CGMS (copy generation management system) for control of copying on a generational basis. Such content control requires co-operation between the suppliers of video content (e.g., DVD vendors, broadcast or signal distribution facilities, etc.) and the manufacturers of compliant equipment (e.g., video recorder manufacturers, PVRs, interface devices, or the like.)
In yet another embodiment, a portion or portions of the HDTV tri-level sync pulse(s) may be modified. For example the positive (or negative) portion of a tri-level sync pulse may be changed in terms of its level. One such example is to lower or increase the amplitude of at least a portion of the positive (or negative) going pulse of a tri-level sync pulse. Depending on which selected tri-level sync pulses are modified, and/or on the level of the modified portion of the tri-level sync pulse, information is conveyed to a content management control system, or at least part of a copy protection signal is produced. It should be noted that a negative and or positive portion of one or more selected tri-level sync pulses may be altered in position and or pulse width; and this type of modification may convey information for a content control system or be used for at least part of a copy protection signal. In this context, copy protection refers to the above-described well known techniques in the video field of altering an otherwise standard video signal so that a conventional receiving device, such as a video recorder, is technically unable to render a useful copy of the video. Copy protection in this context does not require a compliant video recorder (or other compliant receiving device) or any special adaptations therein to be effective.
In yet another embodiment, useful for content control and/or for copy protection, the video signal is modified to cause erroneous results to downstream (receiving) equipment which senses reference portions of the video signal. Such reference portions may include modifications to the amplitude of the positive pulse of a tri-level sync pulse and/or the back porch region following it. For example, on selected scan lines, increasing the level of the positive pulse of the tri-level sync pulse and/or adding a pulse (signal or waveform) in at least a portion of the back porch region, may affect the AGC (automatic gain control) system of a receiving device (e.g., video recorder, video signal distribution network, video signal transmitter), but it may cause minimal effect(s) on a video display device. Furthermore, the addition or insertion of tri-level pseudo sync or tri-level sync pulses which may have modified portions, can also define a copy protection or content control signal. As mentioned above, pseudo sync refers in this context to a process well known in the analog TV field for copy protection where pulses having the same configuration as conventional horizontal synchronization pulses are added to the blanking intervals (typically vertical blanking intervals) to disrupt recording of the video signal by e.g., a VHS video tape recorder, while not having the same disruptive effect on a TV set or monitor. The present added tri-level pulse added signals may have added pseudo sync pulses following them.
With up to three channels (Y, Pb, Pr) of video in HDTV, it is possible to modulate or enable the added pulses dependently or independently on each channel. Modulating or enabling channel independently, for example, can be an advantage to speed up the copy protection effects for a more annoying effect on playback. For instance, if the AGC time constant is about 0.5 second (2 Hz), then “cascading” or modulating the added pulses in multiplexed form between the channels can cause the Y, Pb, and Pr channels (e.g., the entire picture) to fluctuate on playback at an effective 6 Hz rate, which is more effective in terms of copy protection. Of course other frequencies may be adapted for modulation of the pulses or waveforms. On another note, it was discovered on certain component monitors such as an HDTV display, that shifting the sync signal in the Y channel caused an eventual shut down of the display. Thus, it is possible to make a display control system for example by shifting in time the Y channel relative to the other chroma channels as a way to cause certain monitors to shut down or display a more unviewable picture. To restore to normal operation, at least a portion of the Y channel is shifted time wise back, or at least a portion of the chroma channels are shifted time wise to allow a more viewable picture.
Any form of the tri-level pseudo sync pulses or signals or a waveform following them (e.g., a tri-level sync signal or sync signal) may be used for content control. In experiments with commercially available HD monitors, it was found that the overscan area was at least 20 horizontal scan lines for some TFT (thin film transistor) monitor displays and 30 scan lines for some CRT (cathode ray tube) monitor displays. This means that the above modifications may be done on video scan lines outside the vertical blanking area (e.g., on an active portion of the video field or on a selected horizontal blanking interval). (Overscan in the video field refers to active video scan lines that are not displayed by a particular TV set or monitor as being at the (very) top or bottom of the picture or a portion on the right or left side of the picture.)
Also, the above signals may include position separation modulation, pulse-width modulation, frequency modulation, phase modulation, and/or amplitude modulation. Also, the above signals may include a lowering of a tri-level sync pulse back (or front) porch region, such as described similarly for analog TV in Ryan et al. U.S. Pat. No. 5,633,927, incorporated herein by reference in its entirety. In yet another embodiment for copy protection (e.g., a personal video recorder of the TiVo type or digital video recorder such as a hard disk drive or DVD recorder or digital tape recorder), it was found by the inventor that a “gray pulse” in a back porch region on selected lines was enough to cause the recording to have time instability on playback (e.g., playback from a digital recorder). This modified video signal has improved playability over the Morio process for analog TV copy protection (see Morio et al., U.S. Pat. No. 4,100,575 incorporated herein by reference in its entirety) since gray level pulses are used instead of Morio's white level pulses. In this context, gray pulse/signal means generally a signal below peak white level. For example, a 30% to 70%, level of selected duration in a back porch region or a region following an end of a sync signal. This “pulse” may be an arbitrary waveform whose average level is below an average peak white level. The use of gray level pulses is applicable to HDTV signals as well for copy protection (and/or content management).
Other embodiments are various defeat methods to modify or reduce the effects of the above, or to change the outcome of a content control system, and associated defeat apparatus also for modifying or reducing the effects or changing the outcome of same. The defeat methods include receiving a video signal generally conforming to a digital television standard and having tri-level synchronization pulses in blanking intervals of the video signal, where the portion of the video signal associated with the tri-level synchronization pulse has been earlier altered so as to inhibit recording of the video signal or to carry information relating to controlling use thereof, as described above. Further, the defeat method includes modifying the portion of the received video signal associated with at least the tri-level synchronization pulses so as to allow subsequent recording of the video signal or to alter the information relating to controlling the use thereof. The modifying or defeating includes modifying at least one of the tri-level synchronization pulses that was earlier altered. Further, the modifying may occur in at least one of the luma or chroma channels of the video signal. The modifying may include lowering or raising an amplitude of the back porch of the tri-level synchronization pulse to a reference level. The modifying may further include raising the amplitude of the back porch from at least 20% below the peak white level of video signal to the reference level. The modifying may further include altering an amplitude of a portion of the tri-level synchronization pulse to render positive and negative going portions thereof symmetrical rather than asymmetrical. The modifying may further include altering at least one of the position, amplitude or width of the earlier altered tri-level synchronization pulse to a reference level.
Further, the method may include further modifying a plurality of the earlier altered tri-level synchronization pulses in the video signal where the alterations vary between different scan lines of the video signal. Further, the modifying may include deleting or attenuating at least one pulse located in the blanking interval.
Further, the deleted or attenuated pulses may extend into an active video portion of the video scan line prior to their deletion or attenuation. The active video portion may be an overscan portion of a field of the video signal. The modifying may include deleting or attenuating the pulse located in the blanking interval prior to or following the location of the tri-level synchronization pulses. Further, the modifying may include deleting or attenuating the pulse from at least one of the luma or chroma channels of the video signal. Further, the deleted or attenuated pulse may have a portion which is positive or negative going prior to the deletion or attenuation thereof. Further, the deleted or attenuated pulse may have a configuration of the tri-level synchronization pulse prior to its deletion or attenuation.
Further, the modifying may include deleting or attenuating of pulses located in a front or back porch portion of the tri-level synchronization pulse. The modifying may include deleting or attenuating a plurality of pulses located in the blanking interval. The modifying may include deleting or attenuating pulses located in a plurality of a blanking intervals, a character of the deleted or attenuated pulses varying between different of the scan lines of the video signal prior to the deletion or attenuation thereof. The character that varies may be at least one of a position, amplitude, width or number of the pulses.
Further, the deleted attenuated pulse may be a gray level pulse located in a back porch portion of the tri-level synchronization pulse prior to the deletion or attenuation thereof. Further, the deleted attenuated pulse may have a duration one third to double that of the tri-level synchronization pulse prior to the deletion or attenuation thereof.
Further, the digital television standard may be a high-definition television (HDTV) standard. The standard may be one of 720 line progressive scan or 1080 line interlaced scan. The information of the received video signal, at least in part, may define a predetermined command for content management of the video signal.
Additionally, the inhibiting recording of the video signal may be by causing a sensing system and an apparatus receiving the video signal to produce an erroneous output. The altered portion of the video signal may be in at least two channels of the video signal. The alterations may differ between the two channels of the video signal. The alternations may in selective scan lines of the video signal and including active video adjacent to the vertical blanking interval of the video signal.
Also contemplated is an associated apparatus for defeating the above-mentioned modifications or modifying them so as to reduce or eliminate their effect or to alter effects: Hence the apparatus which carries out the above method typically would include an input port adapted for receiving a video signal generally conforming to a digital television standard and having tri-level synchronization pulses in blanking intervals of the video signal, a portion of the video signal associated with the tri-level synchronization pulse having been earlier altered and thereby not necessarily conforming completely to the digital television standard. Also included in the apparatus is a processor coupled to the input port and modifying a portion of the received video signal associated with at least one tri-level synchronization pulse so as to allow subsequent recording of the video signal and/or to alter the information relating to controlling its use. The apparatus further includes an output port coupled to the processor and adapted to output the modified video signal. The modifying may include modifying at least one of the tri-level synchronization pulses that was earlier altered. Further, the apparatus is capable of carrying out each of the various above-mentioned features in terms of the modification method. These features include the following.
The modifying may occur in at least one of the luma or chroma channels of the video signal. The modifying may include lowering or raising an amplitude of the back porch of the tri-level synchronization pulse to a reference level. The modifying may include raising the amplitude of the back porch from at least 20% below the peak white level of the video signal to the reference level. The modifying may include altering an amplitude of a portion of the tri-level synchronization pulse to render positive and negative going portions thereof symmetrical. The modifying may include altering at least one of the position, amplitude or width of the earlier altered tri-level synchronization pulse to a reference level. The processor in the apparatus may further modify a portion of the earlier altered tri-level synchronization pulses in the video signal, the alterations varying between different scan lines of the video signal.
Further, the modifying may include deleting or attenuating at least one pulse located in part of the blanking interval. The deleted or attenuated pulse prior to the deletion or attenuation thereof may extend into an active video portion of the video signal scan line. The active video portion may be an overscan portion of a field of the video signal. The modifying may include deleting or attenuating the pulse located in the blanking interval prior to or following a location of the tri-level synchronization pulse.
The modifying may include deleting or attenuating a pulse from at least one of the luma or chroma channels of the video signal. The deleted or attenuated pulse may have a portion which is positive or negative going prior to the deletion or attenuation thereof. The deleted or attenuated pulse may have a configuration of the tri-level synchronization pulse prior to the deletion or attenuation thereof.
The modifying may include deleting or attenuating a pulse located in a front or back porch portion of the tri-level synchronization pulse prior to the deletion or attenuation thereof. The modifying may include deleting or attenuating a plurality of pulses from the blanking interval. Further, the modifying may include deleting or attenuating pulses located in a plurality of the blanking intervals, a character of the deleted or attenuating pulses varying between different of the scan lines of the video signal prior to the deletion or attenuation thereof. Further, the character that varies may be at least one of a position, amplitude, width or number of the pulses.
Further, the deleted or attenuated pulse may be a gray level pulse located in a back porch portion of the tri-level synchronization pulse prior to the deletion or attenuation thereof. The deleted or attenuating pulse may have a duration one third to double that of the tri-level synchronization pulse prior to the deletion or attenuation thereof.
Generally, the digital television standard may be the high definition television (HDTV) standard. The standard may be one of the 720 line progressive scan or 1080 line interlaced scan.
Further, the information in the receiving video signal may at least in part define a predetermined command for purposes of content management of the video signal.
Additionally, the inhibiting recording of the video signal may be by causing a sensing system in an apparatus receiving the video signal to produce an erroneous output. The altered portion of the video signal may be in at least two of the channels of the video signal. The alterations may differ between the two channels of the video signal. The alterations may be in selected scan lines of the video signal and active video adjacent to the vertical blanking interval of the video signal.
Moreover, in the apparatus the input port may be adapted to receive three channels of the video including one luma and two chroma channels.
Moreover, the output port of the apparatus may be adapted to output three channels of the modified video signal. Moreover, in the apparatus the processor may include a reference signal detector coupled to the input port and having an output port, a memory coupled to the output port of the reference signal detector and adapted to store a plurality of values pertaining to the altered portion of the video signal, and a combiner coupled to the input port of the processor into the memory, an output port of the combiner being coupled to an output port of the apparatus. Further, there may be at least one counter associated with the memory.
BRIEF DESCRIPTION OF THE DRAWINGS
Content Management Modification
As an example, selected scan lines in the Y channel will have an added positive pulse (e.g., pulse or waveform) following a negative and positive (e.g., tri-level sync pulse) reference signal. The selected scan lines are in the VBI (vertical blanking interval) vicinity, such as scan lines toward the bottom of the active field and/or selected scan lines in the VBI, and/or selected scan lines toward the top of the active field. Each signal generator V1, V2, and V3 outputs signals inserted into each channel respectively, for example. Hence these signal generators output waveforms, static or dynamic, to be incorporated into the incoming video program signal. As a further example in the Y channel, the number of pulses referenced to an origin in time, such as the vertical sync pulse, conveys various content control commands, e.g., for a CGMS command set. The use of two (or more) video channels with added pulses can further convey content control commands to a compliant receiving device.
Note that any signal modifications shown in
The modification techniques of
The waveforms of prior art FIGS. 11A-E illustrate that sometimes the negative portion of the tri-level sync pulse is distorted or attenuated, and even an AGC system having higher reliability than one operating as shown in FIGS. 11A-E would rely on sampling the positive going pulse of the tri-level sync and at least part of the back porch region. Thus, the modifications described above to modify at least a portion of the tri-level sync and/or a back porch region, can advantageously affect operation of any such an AGC system or video system that utilizes a tri-level sync pulse video signal, so as to achieve copy protection.
The present inventor has found that for analog TV (not HDTV) for selected lines, raising a portion of the horizontal sync back porch region to a “gray level” such as 40% of peak white level is sufficient to create a copy protection effect on a digital recorder. The resulting playback creates instability on a video display (e.g., TV set). The present inventor also found a similar instability effect can be accomplished by modifying n scan lines of a highly raised back porch portion combined with m scan lines of a lesser raised back porch portion. For example, n can be a cluster of (4 of 12) scan lines at about 100% of peak white level (or near a white level), while m may be the remaining (8 of 12) scan lines in the cluster at about 35% of peak white level (or a gray level) for the raised back porch area.
The separated vertical or frame signal V on line 106, the horizontal line signal (H) on line 107, and the pixel clock reference signal on line 108 are coupled to an addressing and memory circuit 103. With these three signals coupled to addressing and memory circuit 103, any pixel location within a video field or frame may be defined with a corresponding value in the memory of circuit 103. This value from memory circuit 103 then is inserted or added to the (selected) blanking intervals or an overscan portion of the video signal. The memory circuit 103 may be programmed via line(s) 109 by waveform feature control circuit 105 for waveform control. Circuit 105 for example may place raised back porch pulses in selected scan lines of the video signal. Or, circuit 105 may regenerate portions of the video signals to include modified tri-level sync pulses or modified back or front porch levels, or newly generated signals (e.g., tri-level pseudo sync pulses and/or signals following them) in blanking or overscan areas of the video signal. The output signal of memory circuit 103 on lines 111, 112 then contains the modification signal(s) to be inserted or added to combiner/inserter circuit 104. Signal 112 may couple a control signal to 104 that inserts or adds part of a waveform an active portion (and or a blanking portion) of a video signal. Combiner circuit 104 then combines or inserts the signal modification at selected lines (and/or pixel locations) with the incoming video signal from terminal 113 coupled to circuit 104. The output of combiner circuit 104 then is the video modified signal at output terminal 114. For example, see the associated output signal waveforms of
The output horizontal rate signal (H) from sync separator 202 is coupled to a phase locked loop or pixel clock circuit 205, which generates a frequency that is preferably some multiple of the horizontal line frequency H. This pixel clock circuit 205 is preferably locked to the incoming video In signal. The output of the pixel clock circuit 205 and the horizontal line signal (H) are coupled to second counter circuit 206 that generates address bits for second memory circuit 207. One of the output signals of second memory circuit 207 is a pulse timed to a particular pixel of the scan line. This output signal is coupled to a programmable digital timing circuit including circuits 208, 209, 210, and 211. The SET (S) input terminal of set-reset flip flop 208 starts the beginning of a pulse as defined by second memory circuit 207. AND gate 209 gates through pixel frequency pulses to third counter circuit 210. Depending on the preset signals applied to counter circuit 210, the duration of the timing is established. Fourth counter circuit 211 provides the preset values for circuit 210. Fourth counter circuit 211 may provide a static or set number or a varying set of numbers (e.g., numbers counting up and/or then counting down to return to an arbitrary number). The output signal of flip flop circuit 208, at terminal Out 14, is then a pulse of a defined duration or of a varying duration.
By combining the signal at the terminal Out 14 with the signal at the output terminal Out 2 of second memory circuit 207 via logic 212 (see
In
Also, the receiving compliant device 404 may operate in a fashion that is bi-directional. For example, the compliant device 404 may send an identifier signal back to the video source 401, such as a (DVD) media player. By recognizing which compliant devices are allowed to operate (or by recognizing restrictions set upon particular compliant devices), the media itself or media player 401 can apply signal modifications to affect receiving devices 404 in a more independent manner such as not allowing transmission, but allowing display, or allowing recording for a set duration.
Defeating/Reducing/Modifying Effects Of The Modifications
High definition TV signals (or other video signals containing tri-level sync pulses) that have been altered with content control tags/signal or copy protection signals added or inserted as described above, can later (presumably by a different entity) be modified further to change the result of the control signals or tags, and/or modify at least an effect of copy protection signals. In the following description, “tags” may be or include an HDTV CGMS signal, a back porch signal, a front porch signal, a set of selected lines of sync pulse modification (which may include sync deletion in part or in whole), any AGC pulse, any (type of) tri-level pseudo sync signal, a signal inserted or added to selected pixels in one or more TV lines, and or data signal. The tags carry content control commands. In one embodiment, the reference signals, such as tri-level sync signals, may be modified to alter at least an effect or command of the content control.
Note that any such defeat or reducing effect activities or apparatus may be illegal in the U.S. under the Digital Millennium Copyright Act (DMCA) as being intended to make or enable making of unauthorized copies. Hence the following is a technical disclosure, but not intended to induce, encourage or enable any unlawful activity.
For example, if tags or raised back porch signals are inserted for purposes of content control, tri-level sync pulses prior to them may be used by the receiving device to locate the back porch signals. By modifying one or more tri-level sync pulses such as by deleting, position shifting, attenuating, narrowing, and/or level shifting a sufficient portion of selected tri-level sync pulses, then at least one of the inserted back porch signals may not be detected correctly. One can also add a signal to an area or a duration of selected tri-level sync pulse which would then cause an erroneous detection or sync separation of at least a tri-level sync pulse needed to correctly detect a back porch signal. Also in this example, for video which contains tri-level sync pulses, at least a portion of the tag signal or copy protection signal may undergo position shifting, level shifting, narrowing, attenuating, and or deleting. At least a portion of a tag may also have a signal (e.g., interfering signal) inserted or added so as to cause an erroneous detection (e.g., by the receiving device).
In another embodiment, at lease one of the tags is relocated (e.g., the tag may (also) be relocated relative to a sync signal such as a tri-level sync pulse or a vertical sync pulse or signal). For example, if there are ten possible scan line locations of tags, and five of them are used and clustered near a particular scan line, one can change the location of at least one tag to another location. To further illustrate, suppose the tags are back porch pulses located on scan lines 10, 11, 12, 13, and 14, but tags can be located from scan lines 10 to 19. The relocated tags are as in the following example: scan lines 10, 11, 13, 14, and 19. Of course, other examples of relocation are possible. In yet another embodiment, simply modifying at least a portion of a vertical sync pulse so as to cause the compliant device, for example, to misidentify the proper scan line count could throw off the scan line assignments of the tags. For example, if one were to delete the first broad vertical sync pulse and add a broad pulse after the last standard (normal) vertical sync pulse, the scan line count will be off by one count. The scan line count error may cause tags and/or HDTV CGMS signals to be improperly detected. Another example is to modify in an interlaced system the field identification. This field identification alteration can be done by modifying a portion of a vertical sync signal and or horizontal sync signal in one or more VBI. Thus, a data signal associated with a particular field (e.g., odd or even), is assumed to be in another field (e.g., even or odd) because a content control system relies on correct sync signals for locating the data signal. Another way is to just move the data signal to another field, since it is the relative location between data and field or sync signal that determines a correct or incorrect read in a content control system.
In another example of the
Note that the processors of
In one example, reference signal Vsig can be a fixed voltage, and switch 706 replaces any signal (e.g., raised front and or back porch pulse) in the horizontal tri-level sync pulse front and or back porch with the fixed voltage. Also switch 706 may replace at least a video signal region where added pseudo sync pulses and/or AGC pulses reside with the fixed voltage. The resulting output signal OUT via amplifier 710 then has a sufficient portion of content control and/or copy protection signals in the presence of tri-level sync pulses removed or modified to alter the content control command, or to reduce an effect of a copy protection signal. It should be noted that to just remove or modify back porch signals, the output terminal of timing circuit 704 may be coupled directly to switch 706, and then components 707, 708, 703, and 702 are not required.
In
The apparatus of
The apparatus of
Yet another output signal of the apparatus of
In yet other embodiments for example, content control (for HDTV or non HDTV) may incorporate the use of multi-directional (e.g., bi-directional) communication(s) or link(s). A link would be able “tell” a content control system the type of device being used, and the content control system may output an appropriate content control or device management signal. The content control system may also direct the device to send out a signal modification to another device to yet another layer of content control or content protection. Embodiments thus may include any combination of adding or inserting of signals, or deleting, to selected pixels of an HDTV signal. Yet another embodiment is a content control system in a computer-like network situation, whereby one or more sources/devices are sensed and appropriate signals or commands are sent via the network to allow for flexible content control or content protection of the various devices.
It should be noted that for some content control or copy/display protection signals, extra signal enhancement(s) may be used such as those described (for analog TV) in Wonfor et al. U.S. Pat. No. 5,583,936. incorporated herein by reference in its entirety. These types of signal enhancements may be made, in accordance with this disclosure, part of the overall HDTV signal. These signal enhancements can cause a more effective HDTV copy or display protection process or simply be part of a copy or display protection signal. For example, if some of the embodiments here cause an AGC reaction, the enhancements may increase or modify the effects or effectiveness. If some of the embodiments cause a display to produce a generally unviewable picture (e.g., via clamp errors in a display device or video interface unit), the enhancements may cause a more unviewable picture. Therefore, a signal modification enhancement as in U.S. Pat. No. 5,583,936 may insert modulated signals to HDTV lines in the bottom or top portion of the TV field to cause increased loss in entertainment value (e.g., such as more tearing or instability on an HDTV display or more noise/interference on an HD device). The enhancement method of U.S. Pat. No. 5,583,936 may also be adapted for HDTV as any combination of blanking a portion of selected lines, adding a signal to selected line portion or portions, deleting, or narrowing or attenuating to a portion in the HBI or VBI or selected pixels of an HDTV signal. Also, defeating or reducing or modifying effects methods as disclosed in U.S. Pat. No. 5,583,936 are applicable in the HDTV context (e.g., with content control signals or copy/display protection signals) as well.
This disclosure is illustrative but not limiting; further modifications will be apparent to one skilled in the art in light of this disclosure and are intended to fall within the scope of the appended claims.
Claims
1. A method of modifying a video signal, comprising the acts of:
- receiving a video signal generally conforming to a digital television standard and having tri-level synchronization pulses in blanking intervals of the video signal, wherein a portion of the video signal associated with the tri-level synchronization pulse has been earlier altered so as to inhibit recording of the video signal or to carry information relating to controlling use thereof, and
- modifying the portion of the received video signal associated with at least the tri-level synchronization pulses so as to allow subsequent recording of the video signal or to alter the information relating to controlling the use thereof.
2. The method of claim 1, wherein the act of modifying includes modifying at least one of the tri-level synchronization pulses that has been earlier altered.
3. The method of claim 2, wherein the modifying occurs in at least one of the luma or chroma channels of the video signal.
4. The method of claim 2, wherein the act of modifying includes lowering or raising an amplitude of the back porch of the tri-level synchronization pulse to a reference level.
5. The method of claim 4, wherein the act of modifying includes raising the amplitude of the back porch from at least 20% below the peak white level of the video signal to the reference level.
6. The method of claim 4, wherein the act of modifying includes altering an amplitude of a portion of the tri-level synchronization pulse to render positive and negative going portions thereof symmetrical.
7. The method of claim 2, wherein the act of modifying includes altering at least one of a position, amplitude, or width of the earlier altered tri-level synchronization pulse to a reference level.
8. The method of claim 2, further comprising the act of modifying a plurality of the earlier altered tri-level synchronization pulses in the video signal, the alterations varying between different scan lines of the video signal.
9. The method of claim 1, wherein the act of modifying includes deleting or attenuating at least one pulse located in the blanking interval.
10. The method of claim 9, wherein the deleted or attenuated pulse extends into an active video portion of the video signal scan line prior to the deletion or attenuation thereof.
11. The method of claim 10 wherein the active video portion is an overscan portion of a field of the video signal.
12. The method of claim 9, wherein the act of modifying includes deleting or attenuating the pulse located in the blanking interval prior to or following a location of the tri-level synchronization pulses.
13. The method of claim 9, wherein the act of modifying includes deleting or attenuating the pulse from at least one of the luma or chroma channels of the video signal.
14. The method of claim 9, wherein the deleted or attenuated pulse has a portion which is positive or negative going prior to the deletion or attenuation thereof.
15. The method of claim 9, wherein the deleted or attenuated pulse has a configuration of the tri-level synchronization pulse prior to the deletion or attenuation thereof.
16. The method of claim 9, wherein the act of modifying includes deleting or attenuating a pulse located in a front or back porch portion of the tri-level synchronization pulse.
17. The method of claim 9, wherein the act of modifying includes deleting or attenuating a plurality of pulses located in the blanking interval.
18. The method of claim 9, wherein the act of modifying includes deleting or attenuating pulses located in a plurality of the blanking intervals, a character of the deleted or attenuated pulses varying between different of the scan lines of the video signal prior to the deletion or attenuation thereof.
19. The method of claim 18, wherein the character that varies is at least one of a position, amplitude, width, or number of the pulses.
20. The method of claim 9, wherein the deleted or attenuated pulse is a gray level pulse and is located in a back porch portion of the tri-level synchronization pulse prior to the deletion or attenuation thereof.
21. The method of claim 9, wherein the deleted or attenuated pulse has a duration one third to double that of the tri-level synchronization pulse prior to the deletion or attenuation thereof.
22. The method of claim 1, wherein the digital television standard is a high definition television (HDTV) standard.
23. The method of claim 1, wherein the standard is one of 720 line progressive scan (720p) or 1080 line interlaced (1080i) scan.
24. The method of claim 1, wherein the information in the received video signal at least in part defines a predetermined command for content management of the video signal.
25. The method of claim 1, wherein the inhibiting recording of the video signal is by causing a sensing system in an apparatus receiving the video signal to produce an erroneous output.
26. The method of claim 1, wherein the altered portion of the video signal is in at least two channels of the video signal.
27. The method of claim 26, wherein the alterations to the video signal differ between the two channels of the video signal.
28. The method of claim 1, wherein the alterations are in selected scan lines of the video signal in active video adjacent to the vertical blanking interval of the video signal.
29. Apparatus for modifying a video signal, comprising:
- an input port adapted for receiving a video signal generally conforming to a digital television standard and having tri-level synchronization pulses in blanking intervals of the video signal, a portion of the video signal associated with the tri-level synchronization pulse having been earlier altered;
- a processor coupled to the input port and modifying a portion of the received video signal associated with at least one tri-level synchronization pulse so as to allow subsequent recording of the video signal or to alter the information relating to controlling the use thereof; and
- an output port coupled to the processor and adapted to output the modified video signal.
30. The apparatus of claim 29, wherein the modifying includes modifying at least one of the tri-level synchronization pulses that was earlier altered.
Type: Application
Filed: Oct 25, 2005
Publication Date: May 4, 2006
Applicant: MACROVISION CORPORATION (Santa Clara, CA)
Inventor: Ronald Quan (Cupertino, CA)
Application Number: 11/259,497
International Classification: H04N 7/167 (20060101);