HK1145581A - Method and apparatus for synthesizing a copy protection or content control signal with improved playability of a tv set - Google Patents

Description

Method and apparatus for combining copy protection or content control signals with improved television playback

Cross Reference to Related Applications

This application claims benefit of U.S. provisional application serial No. 60/965,704 filed on day 8, 22 of 2007.

Technical Field

The present invention relates to copy protected video signals that typically produce playable pictures when the video program signal is coupled to a television monitor, but which result in providing a degraded video program signal to a video recorder.

Background

Previous attempts to add Automatic Gain Control (AGC) pulses or back porch pulses in the horizontal blanking interval (e.g., a portion of the back porch) have resulted in varying degrees of play-out artifacts (playback artifacts).

For example, the copy protection system disclosed in Morio, U.S. Pat. No. 4,163,253, adds trailing edge AGC pulses in a continuous manner during active video fields. But this results in a significant dimming effect on a television set using the trailing edge sample clamp. See, for example, AGC pulses 12 shown in dotted lines in fig. 1.

One variation on the Morio patent is to add trailing edge AGC pulses in a non-continuous manner or in groups (see U.S. Pat. No. 4,819,098 to Ryan). The addition of a trailing edge signal to a selected one of every N television lines in the active television field provides an improvement that reduces the dimming effect experienced in the system of the Morio (' 253) patent. However, in some televisions, the system disclosed in the Ryan' 098 patent, which selects one out of every N lines, results in a slight dimming of the display of the selected one out of the N lines, i.e., it results in a "Venetian blind" (dimming) effect.

Similarly, adding AGC pulses in a set of television lines also reduces the dimming effect experienced by the system disclosed in the Morio (' 253) patent. For this purpose, some AGC pulse sets should be located away from the television line in the active field portion, or in the visible range of the video field. This limits the number of AGC pulse sets that can be used.

Thus, adding trailing edge pulses in a 1/N manner appears to be successful in reducing the overall darkening effect in the Morio (' 253) patent, but causes a louvre effect. This louver effect is darkened every N lines. For example, if a back porch pulse is added to a selected one of every ten lines, every ten lines will appear a little darker for some displays. This shutter effect may be more pronounced in new television sets with analog-to-digital converters and/or digital processing.

For the Morio ('253) and Ryan (' 098) patents, there is an alternative to a system that adds a reduced trailing edge signal to a portion of the trailing edge of the selected television line to partially cancel or substantially eliminate the dimming effect caused when an AGC pulse is added to the trailing edge. (see, for example, Ryan U.S. patent No. 6,188,832). However, the reduced back porch signal may cause some television display devices to display excessively bright pictures. This solution may cause "bright" artifacts in some televisions.

Another copy protection system is disclosed in Tan international patent WO2004/004346a1, which shows the addition of AGC pulses on each line in a video field throughout a visible or active television line of sight. Preferably, these AGC pulses are added prior to the burst signal to avoid the darkening effect of the Morio device. However, while Tan's process may result in less dimming than Morio's process, there may also be significant dimming results in some television display devices. See the AGC pulses of fig. 2A, which also shows the "narrowed" sync pulse 16, AGC pulse 12, followed by the trailing edge of the narrowed horizontal sync pulse.

Summary of The Invention

It is an object of the present invention to produce a copy protected video signal that results in an automatic gain control effect on a Video Cassette Recorder (VCR) or video device that improves playback (e.g., reduced shutter effect or reduced dimming effect) in a television monitor while utilizing an automatic gain control amplifier (AGC amplifier).

Another object of the present invention is to further improve to reduce the darkening effect experienced in the previously mentioned systems of us patent nos. 4,163,253 and 4,819,098 and/or WO2004/004346a 1.

It is another object of the present invention to improve the time base instability of a television display apparatus. Sometimes, timing instability is caused by adding a positive level-shifting pulse in the Horizontal Blanking Interval (HBI), which includes shifting a portion of the sync pulse toward a blanking level or toward a gray or white level.

It is a further object of this invention to improve to reduce the darkening effect experienced in video signals that are processed or otherwise provided with two or more negative-going pulses in a selected Horizontal Blanking Interval (HBI) or in a range within the HBI and its peripheral region.

Another object is to improve the time base stability of a television display device for video signals that may include more than one sync-like pulse (e.g., pulses of-200 to-320 millivolts from the blanking level, each pulse having a pulse width that can be sensed/affected by the timing circuitry of any video device; e.g., sync separators and/or lock oscillators). While multiple sync-like pulses within a horizontal timing interval can cause display image tearing/display instability in some display devices, such as display devices with digital signal processing, or some flat screen monitors.

Another object of the present invention includes using multiple class sync pulses to provide content control commands to a content control system.

Another object of the present invention can also include methods and apparatus for sensing or reading an AGC signal sequence to provide one or more commands in a content control system. For example, the beginning and/or end (line) of an AGC pulse, or the sensing of dissimilar AGC pulses, may define a content control command.

It is to be understood that the present invention may include one or more of the following configurations or concepts.

1) And correcting the selected color burst signal. For example one or more widened or shortened color burst envelopes.

2) Modification of the selected horizontal blanking interval. E.g., one or more widened or narrowed horizontal blanking intervals.

3) Video lines that normally do not have AGC pulses (or weak AGC pulses) are filled with AGC pulses with a selected intermediate value to reduce the effect of the shutter to improve playback. For example, if N > -3, 1 of the N lines will have AGC pulses, and the other lines that do not have AGC pulses may have AGC pulses whose values are preselected. For example, the value may start at 80% white and the energy of the value will decrease until the next nth AGC pulse occurs. For another example, if N is 6, the AGC pulses for every N lines may be set around the white peak, while the AGC pulses for (each) of the other lines may be set to a value in the range from 80% to 20% white. Of course, other values and/or ranges of N are possible.

By way of general description, embodiments of the present invention may use AGC signals that are dissimilar from one television line to another in one or more portions of the active field. For example, one AGC pulse on a television line may have an amplitude of X millivolts and a duration of X1, while a pulse on another television line may have an amplitude of Y millivolts and a duration of Y1. In another example, every P lines may have a characteristic of X followed by Q lines with a characteristic of Y. Of course, there can be more than X or Y feature types (e.g., A, B, c.

Another general description of embodiments of the present invention is that any two dissimilar AGC pulses (which may include zero AGC pulses) may be provided within the active field. For example, the AGC pulses may vary in amplitude and/or pulse width in any number of combinations or sequences. Thus, the selected number of AGC pulses in a portion of the active field may be a plurality of values (e.g., > -2 values).

For example, one of the M lines may have an AGC signal amplitude that is less than the AGC signal amplitude in the (M-1) line (or vice versa).

An alternative overview of another embodiment of the present invention is that it provides AGC and/or sync pulses that are modulated/modified. Preferably, the modulation/modification of the AGC and/or synchronization pulses occurs in at least a portion of the active or visible range. For example, the modification of the AGC pulses during a portion of the visible or active field provides advantages in improving playback artifacts such as dimming, and/or time base stability of the display device. Examples of modulation may include modulation of position, phase, amplitude, duration (e.g., pulse width), pulse coding, and/or frequency.

The present invention therefore provides an alternative solution for the grouping of AGC pulses on a television line, such as that disclosed in prior art U.S. patent No. 4,819,098, which relies on the grouping of AGC pulses (preferably in an overscan area outside the visible video field) to minimize the effects of play on a television monitor or display device, as previously mentioned.

In addition, the present invention improves playback with respect to previous attempts, namely (e.g., U.S. Pat. No. 4,163,253) by actually adding a back porch AGC pulse to each active field video line, or (U.S. Pat. No. 4,819,098) by providing a 1/N line sequence for providing back porch pulses and the like for AGC effects, resulting in playback problems on at least some television display devices.

In addition, the present invention improves the playback (e.g., reduces dimming) of other prior art processing techniques in which the AGC back porch or HBI pulse is provided on a selected one of the three television lines, also resulting in some dimming effect on the television. In some cases, the dimming effect of the processing of a selected one of the three lines may result in a noticeable shutter effect on some televisions. (e.g., other combinations such as 2 for 3 TV lines or p for q TV lines with AGC, HBI pulses, which combinations may be implemented for embodiments of the present invention. for example, the number "p" > 1. TV lines with AGC pulses may follow a periodic or aperiodic or preprogrammed sequence

In some television monitors it is recommended that the trailing edge pulses in the active field should exceed the rate at which one out of every three television lines is selected. Or different combinations of AGC pulse sets may be inserted into the lines of the active field to cause the playback on the display device to be acceptable.

In selected embodiments, where the AGC pulses in the active television field are static but combined, the modulated AGC pulses may be added to a line near and/or within the vertical blanking interval. These modulated AGC pulses are then combined with static AGC pulses in the active field, resulting in dynamic effects on the AGC system.

In addition, burst corrections such as providing a high frequency signal in the trailing edge/HBI region of a particular phase and/or frequency, and/or any enhanced copy protection signal or correction such as a reduced trailing or leading edge portion, end of field/line waveform, sync correction, etc., such as described in U.S. patent No. 5,583,936, may be used in combination with active field AGC pulses.

Alternative embodiments of the present invention utilize any active field AGC pulses as content control commands for delivering content control.

In addition, the present invention may include an adaptive apparatus or method or means for modifying the AGC signal based on the actual video program signal.

The present invention may provide more than one negative going pulse in the HBI of the selected television line. In the example where two or more negative going pulses are provided for one of the N lines, the negative going pulses will not cause a significant timing error on the display device. For example, providing two "sync-like" pulses for every 10 lines will not cause a horizontal phase-locked loop (H PLL) in the display device to tilt erroneously, and it will therefore also produce an acceptable video program display. It is to be appreciated that each negative going pulse in the HBI may be followed by a positive going pulse (e.g., for AGC effects).

Improvements to the prior art, such as the '098 and' 253 patents, include: synchronization narrowing, analysis of horizontal sync pulses, and/or insertion/addition of AGC pulses away from the back porch region (e.g., at a rate of one AGC pulse per N lines), and/or transfer/correction of horizontal sync pulses of the television line without AGC pulses (e.g., (N-1) lines).

By way of example, if this (N-1) line shifts or delays H sync, the back porch sampling in the television will occur later on the back porch region (for the case where one of the N lines is selected with an AGC pulse), thereby avoiding sampling of the inserted AGC pulse and thereby reducing play-out artifacts.

It should be appreciated that the active or viewable pixels may be rescaled, shifted, and/or pruned to allow the television line of sight to shift or delay H synchronization to provide a substantially "centered" picture on the television display device.

Other embodiments of the invention may include any of the waveforms mentioned in the' 936 patent, such as: providing a reduced portion, or a portion of the video signal, on the leading and/or trailing edge; sync width modification (e.g., narrowing, widening, amplitude change, and/or position); adding/inserting a waveform of 100KHz to 5MHz to a part of the video signal; or use FM, AM, PWM, and/or PPM signals.

The present invention is incorporated by reference into U.S. patent No. 6,381,747 (Wonfor et al). For example, reference is made to figures 1, 2 and 3, together with their (detailed) description in their description, and tables 1 and 2 found in columns 11 and 12 of the patent.

It should be noted that any of the embodiments described previously, or any of the embodiments described in the following description, may be used in combination with other copy protection signals or modifications to the video signal, such as: the synchronization is reduced; adding the selected waveform to one or more portions of the video signal; pseudo-synchronizing; pseudo sync/AGC pulse pairs; correcting the front edge or the back edge; performing substrate correction on the selected television line; color synchronization correction; luminance and/or chrominance channel modification. Moreover, any of the methods, modifications, or processes mentioned previously or hereafter may be implemented in any combination of television standards (e.g., standard definition, progressive scan, interlaced scan, and/or high definition).

Brief Description of Drawings

Fig. 1 is a waveform diagram showing normal horizontal synchronization (10) in a video signal with AGC pulses 12 shown in dotted lines to represent prior art processing (e.g., U.S. patent No. 4,163,253). The dashed line 14 depicts a continuous video line of the video program signal.

Fig. 2A is a waveform diagram illustrating an embodiment of the present invention in which AGC pulses vary in energy and/or position from a particular line to another line. The embodiment of fig. 2A may also include narrowed horizontal (H) sync pulses, e.g., with or without dissimilar AGC pulses for each line, to improve time base stability or playback in the display device.

Fig. 2B is a waveform diagram illustrating the amplitude change in the AGC pulses from one video line to another.

Fig. 3 is a waveform diagram illustrating another embodiment including level shifting in the horizontal synchronization section.

Fig. 4 is a waveform diagram illustrating another embodiment with negative and positive going pulses added during selected horizontal blanking intervals.

Fig. 5 is a waveform diagram showing yet another embodiment with horizontal sync pulses where the horizontal sync pulses from one television line to another line are dissimilar, as well as the AGC pulses inserted or added from one line to another line.

Fig. 6 is a waveform diagram illustrating another embodiment including different sync pulses, and/or different level shifting pulses from one line to another.

Fig. 7 is a waveform diagram illustrating another embodiment of the present invention, which is, for example, a variation of the waveform in fig. 4.

Fig. 8 is a waveform diagram showing a video signal of the prior art.

Fig. 9 is a waveform diagram showing another embodiment with multiple sync-like pulses and AGC pulses.

Fig. 10 is a waveform diagram further illustrating an embodiment of the present invention for improving playback.

Fig. 11 is a waveform diagram illustrating another embodiment of the present invention for improving playback.

FIG. 12 is a block diagram illustrating an apparatus according to one or more embodiments of the invention.

FIG. 13 is a block diagram illustrating another apparatus according to one or more embodiments of the invention.

FIG. 14 is a block diagram that also illustrates another apparatus in accordance with one or more embodiments of the invention.

FIG. 15 is a block diagram illustrating another apparatus according to one or more embodiments of the invention.

FIG. 16 is a block diagram illustrating at least a portion of a content control system that utilizes one or more embodiments of the present invention.

Fig. 17 is a block diagram illustrating an apparatus for implementing one or more of the various embodiments of the invention, and/or other video signal modifications.

Detailed Description

The video signal shown in fig. 1 is provided with normal horizontal sync pulses 10 and includes AGC pulses 12 shown in dotted lines to illustrate prior art processing such as disclosed in us patent No. 4,163,253, or WO2004/004346a 1. The latter process above also requires narrowed H-syncs. Throughout the active field, the continuous line has AGC pulses that cause a dimming effect on the television monitor.

Fig. 2A shows a waveform with a narrowed H sync 16, which narrowed H sync 16 is combined with AGC pulses 12 and AGC pulses 12' (shown in dotted lines). In the invention depicted in fig. 2A, the AGC pulses 12 or 12' (but typically not both) may be set to a lower level/amplitude. For example, the AGC pulses 12 may be set to a white level and the AGC pulses 12' may be set to a gray level or may be set to a black/blanking level. It is noted that the dissimilar AGC pulses 12 and 12' provided in the video signal define the basis of the present invention. In addition, one or more narrowed H sync 16 may be changed to a normal sync pulse or wider than a normal sync pulse and may be combined with dissimilar AGC pulses 12 and 12'. For example, providing a sequence of AGC pulses with alternating white and blanking levels over a portion of the active field results in a reduced dimming effect when compared to the original process of including AGC pulses of a white level throughout the active field (with a narrowed H sync pulse). This embodiment of alternating one AGC level with another AGC level (with narrowed H sync pulses) shows that the shutter effect is reduced when compared to the prior art. It is noted that other sequences of AGC pulses at different energy levels (or positions) can also result in better playback. In general, embodiments of the present invention include a narrowed horizontal sync and 2 or more dissimilar AGC pulses (e.g., finite or zero energy AGC pulses may be used) in at least a portion of one or more active television fields. The AGC pulses may be provided in a periodic, aperiodic, and/or programmed sequence.

As previously discussed, the present invention is advantageous in that it provides improved playback and/or reduced artifacts on a display device when compared to existing anti-copy processing techniques by providing a first number of lines with a particular AGC signal, followed by a second number of lines with a different AGC signal, or with forward pulses of different amplitude, which lines can include attenuated (or near zero) AGC pulses. It is noted that the first and second number of video lines may be equal to each other, greater than each other, or less than each other. For example, if the first number is equal to R and the second number is equal to S, there are three possibilities; i.e., R S, R > S, or R < S. It will be apparent that more than two numbers may be used, e.g., R, S, t.

Fig. 2A illustrates an embodiment in which 1 out of 2 video lines has AGC pulses 12, with zero AGC pulses 12' arranged between the pulses 12. But other numbers are also possible, such as 1 out of N lines, or M1 AGC pulses per N lines, or the like. For example, two video lines with AGC pulses may be used followed by one line without AGC pulses. Another example is to provide or synthesize a modulated number of AGC pulses (positive going pulses), for example in a portion of the active field and/or VBI, where two or more AGC pulses have different energies (e.g., powers or voltages or currents, which can be finite or zero) and/or positions.

It should be noted that either the multi-line AGC pulses or the zero amplitude AGC pulses may be replaced with fixed energy level AGC pulses; e.g., lower/higher amplitude AGC pulses, and/or shorter/longer duration AGC pulses.

Fig. 2B illustrates an embodiment of the present invention in which a sequence of (three) video lines includes AGC pulses with decreasing energy. In this example, for the first video line in the sequence, the AGC pulse 12^*With an amplitude of 100% white or 100 IRE. On the second line in the sequence, the AGC pulses 12^**Having an amplitude of 50% white, followed by a pulse 12 with AGC^***The third video line of (2), the AGC pulse 12^***With an amplitude of 25% white. As seen on the fourth video line,with AGC pulses 12^*The sequence was repeated (100% white). For example, to provide a copy protection signal with improved playback, or reduced dimming, or reduced blinds effect, other sequences (e.g., sequences of P or N video lines), amplitudes, pulse widths, and/or positions of AGC pulses or forward-varying signals (in one or more horizontal blanking intervals) can be implemented or synthesized. It is noted that one or more of the horizontal sync pulses shown in fig. 2B may have a narrowed, normal, or widened pulse width.

Figures 3 and 4 show similar techniques for providing AGC pulses that are dissimilar from one television line to another, but with sync pulses 18 that are jagged per line as shown in figure 3 and with added, negative going sync-like pulses 20 in figure 4. In both fig. 3 and 4, positive going (AGC) pulses 22 and 24, and/or 22 'and 24' are added, which are located away from the trailing edge of the television signal. This minimizes the sampling from the display device and thereby further reduces the dimming effect. To improve the playback of the video signal in accordance with the present invention, the energy of the AGC pulses 22 'and 24' should be less than the energy of the AGC pulses 22 and 24, respectively.

In fig. 5, 6 and 7, some normal sync pulses 10 are provided, and the technique is able to obtain sufficient time base playback when other sync pulses, such as sync pulses 16 (fig. 2), 18 (fig. 3), and 20 (fig. 4), are not normal. In some display devices, the normal sync pulse should be modified to minimize image tearing. One solution for minimizing time base instability on a display device is to apply the same type of synchronization pulse throughout a portion of the visible video field. For example, the normal sync pulse 10 is modified to the sync pulse 16 of fig. 2, the sync pulse 18 of fig. 3, and/or the sync pulse 20 of fig. 4. Another solution for minimizing image tearing is to adjust the position/width of the normal and/or modified sync pulses.

It is noted that alternative embodiments of the present invention shown in fig. 5, 6 and 7 are for improving the playback (e.g., reducing the dimming), for example, by deliberately letting the amplitude and/or pulse width of the forward (AGC) pulses 30 ', 32 ' and 34 ' be smaller than the amplitude and/or pulse width of the pulses 30, 32 and 34, respectively, which may include zero active component. (Note that in FIG. 5, sync pulse 10 is typically wider than sync pulse 16.)

Fig. 8 illustrates a prior art processing technique, whose playability can be improved by reducing the darkening caused by the processing technique. In fig. 8, there are two sync-like pulses 36 and 38, and two (equal) AGC pulses substantially in the horizontal blanking interval (and its periphery). The improvement in playback in the process of fig. 8 is achieved in accordance with the present invention by lowering the energy levels of all or selected AGC pulses 40 and/or 42, which then results in a process for reducing dimming in a display device.

Fig. 9 illustrates an example of modifying one or more AGC pulses in a selected video line to improve playback compared to the prior art shown in fig. 8. For example, every N video lines, AGC pulses 42 are replaced with AGC pulses 42 ', pulses 42' < 42 by energy. Alternatively, AGC pulses 40 may be replaced with equivalent pulses 40 '(not shown) in every N lines, which results in per-energy AGC pulses 40' < 40. It is to be understood that zero energy may be included in one or more of AGC pulses 40 ' (not shown) or 42 ' (fig. 10), and 40, 40 ', and/or 42. In addition, the AGC pulses may vary in position or in pulse duration/width (as part of the waveforms in fig. 9-11).

Fig. 10 shows another example of a modification to the prior art processing of fig. 8 for improving the playback of a video signal. Here, every N video lines, two positive pulses are energy level blanked or modified. For example, the energy of AGC pulses 40' and 42 "in fig. 10 is less than the energy of AGC pulses 40 and 42, respectively, in fig. 8, every N lines.

Fig. 11 shows another example of modifying the prior art waveform of fig. 8 to improve video signal playback. For this purpose, the two AGC pulses contained by the selected line are replaced by a synchronization pulse, such as the normal synchronization pulse 10 in the previous figure. FIG. 11 also shows that positive going pulses 40 "and 42'" can be added. For example, if a normal sync pulse 10 is inserted on a selected line, there may be some timing errors (e.g., picture tearing) in some televisions. Adding a positive going pulse 40 "with a positive level at least half the sync level will reduce picture tearing. It is noted that picture tearing may be reduced by adjusting the position and/or width of the normal sync pulse 10 or by using a modified sync pulse (e.g. a narrowed or widened sync, or a sync with a changed position or amplitude).

Fig. 12 illustrates a device 50, such as a digital player, media player, cellular telephone, set-top box (STB), receiver, television, wireless device, network appliance, computer, video recorder, player, integrated circuit, and/or the like, capable of utilizing any combination of the aforementioned implementations and/or techniques to provide content control commands, or at least a portion of an anti-copy signal. Device 50 may include control bits to program and/or enable various signals and/or alterations of the described signals or waveforms.

Fig. 13 shows a wireless receiving device 52 that may include circuitry for encoding or synthesizing any of the previously described signals.

Fig. 14 shows a device 54 which may comprise one or more inputs and one or more outputs and comprises an RF output 2 for transmitting any of the mentioned signals. The device 54 may also provide another output 1, such as a video output, a digital output, etc., which provides any of the mentioned signals.

Fig. 15 shows a device 56 comprising a receiver or tuner section 58 and a reader 60 for reading or sensing at least a portion of the control bits and/or any of the aforementioned signals, such as content control commands and/or copy protection signals. The device 56 may include a generator 62 for providing any of the mentioned signals. Alternatively, the device 56 may include a recording device 64 and/or a transmitting device.

The sensor/reader 60 in the device 56, which may be an embodiment of the present invention, may output a signal (whether used or not) indicative of the presence of any of the signals discussed above, for example, with respect to fig. 1-11. The sensor/reader 60 may sense or read a plurality of negative going pulses, such as any of those shown in fig. 3, 4, 6-11, and/or any vertical (or horizontal) sync pulses that are jagged. The sensor/reader 60 may read AGC pulses, pseudo sync pulses, narrowed H sync pulses, modified vertical (V) sync pulses, burst modification signals such as color stripe syncs (color stripe syncs), split syncs, widened/narrowed sync envelopes, segmented phase/amplitude color sync envelopes, added phased cycles, phase modulated color sync envelopes, frequency shifted sync envelopes, and/or amplitude modulated sync envelopes.

Fig. 16 shows a device 70 for generating content control commands. The device 70 includes a content control device 72 that preferably receives signals from a reader or sensor circuit (such as the sensor/reader 60 in the device 56 of fig. 15) and outputs content control commands. This command can modify a video recorder, player, receiver, television, computer, cellular telephone, digital network, digital camera, etc. for viewing, recording, transmission functions, and/or for coupling to modification circuitry 74. For example, the modification circuit 74 may employ the input (video) signal to effect any changes such as inserting or adding the previously mentioned signals to the (video) signal. The correction circuit 74 may include a modulator.

Fig. 17 shows a general apparatus for correcting a video signal. For this purpose, the processor circuit 80 has inputs or registers for providing line positions and/or pixel positions of the video signal. The output of the processor circuit 80 can then provide or synthesize the content control command or any change in the portion of the copy protection signal mentioned earlier. The processor circuit 80 may be controlled by control and/or configuration bits. The processor circuit 80 may include (provide, generate, and/or synthesize) pseudo sync/AGC pulses, reduced portions of video (e.g., reduced portions in leading edges, trailing edges, and/or active video lines), and/or color burst correction signals such as color stripe syncs, split syncs, widened/narrowed sync envelopes, segmented phase/amplitude color burst envelopes, added phased loops, phase modulated color burst envelopes, frequency shifted sync envelopes, and/or amplitude modulated sync envelopes (e.g., portions of all). The processor circuit 80 may include means for programming the sequence of AGC pulses described previously and/or may program the width and/or location of the synchronization in the video signal.

The features and advantages of the invention, illustrated above in various embodiments, may be summarized as follows:

the present invention advantageously improves the playback of copy protected video signals, wherein the copy protected signals comprise AGC pulses in video lines in a portion of a valid or visible video field or frame, and wherein the AGC pulses comprise non-similar AGC signals from one video line to another video line. This improves the playback on the television set by, for example, reducing the dimming effect or the shutter dimming effect in the video signal.

Embodiments of the present invention arrange the non-similar AGC signals in a video line in a portion of the video signal, including at least two non-similar AGC signals in a video line present in a visible or visible portion of the television field or frame.

Another embodiment senses or reads a non-similar AGC signal in a portion of the active field or frame, where sensing or reading a non-similar AGC pulse generates a signal that can be used as a content control command in a content control system.

It is intended that embodiments of the present invention may delete, blank, and/or attenuate one or more of the AGC signals.

In another embodiment, the pulse width and/or amplitude of the selected synchronization signal or synchronization pulse is reduced.

The present invention advantageously reduces the effects of darkening in a video display apparatus for video signals that include back porch pulses of constant amplitude during time intervals indicative of active video field portions, and provides or synthesizes a content control signal or copy protection signal by including back porch pulses of non-similar pulse width, position, and/or amplitude from one video line to another, wherein the content control signal or copy protection signal exhibits reduced effects of darkening. The content control signal or copy protection signal provided or synthesized may include reduced AGC pulse width, and/or amplitude, and/or reduced amplitude horizontal and/or vertical sync pulses, or may include position modulated AGC pulses.

The aforementioned embodiments also contemplate one or more copy protection enhancement signals being synthesized, provided or included in the video signal, the content control signal, the copy protection signal, and/or the provided video signal.

Additionally, the aforementioned embodiments may include added negative and/or positive going pulses.

Another embodiment of the present invention includes a method and apparatus for modulating forward pulses or AGC pulses, wherein the modulated forward pulses and/or AGC pulses may include any combination of amplitude, position, pulse coding, frequency, pulse width, and/or phase modulation.

The aforementioned embodiments may include a negative going pulse or sync pulse or pseudo sync pulse in a portion of the active field that is added, inserted, widened, narrowed, and/or positioned to reduce timing instability or image tearing when the video signal is displayed on a monitor.

Another embodiment of the invention provides a content control signal, or at least a portion of an anti-copy signal, to a video signal and includes adding or inserting a forward pulse in a selected horizontal interval, wherein the selected horizontal interval includes a narrowed or modified sync pulse, and which may also include a forward pulse that changes in amplitude, phase, position, and/or duration from the position of one video line to the position of another video line in at least a portion of the visual range of the video field. In addition, a signal in the range of 100kHz to 30MHz may be added to a part of the video signal. In addition, the signal may be added to a portion of a vertical synchronization signal that is in a portion or interval of a vertical blanking interval.

In another embodiment, a signal is added for enhanced playback, the signal comprising at least one of: a modulated waveform extending below a blanking level for a period of time; a reduced trailing edge signal; a reduced leading edge signal; a dynamic gray to at least black signal (dynamic gray to at least eastblack signal); blanking/black/grey/white to a signal below the blanking level which has a small negative value compared to the sync pulse top level (e.g. a small negative value compared to the sync pulse top level, can be a level above the sync pulse top level).

The previously mentioned embodiments may include a positive going pulse, for example, located before the burst, and/or just where the trailing edge region begins, such as within the first quarter or half of the trailing edge region.

The following U.S. patents are incorporated herein by reference: 4,819,098; 4,907,093, respectively; 5,315,448, respectively; 5,583,936; 5,784,523, respectively; 6,381,747, respectively; 6,516,132, respectively; 6,600,873, respectively; 6,836,549, respectively; 7,039,294, respectively; 7,050,698, respectively; 7,085,380, respectively; and 7,236,683.

It should be noted that any of the above incorporated patented methods/apparatus may be combined with any of the components of the present invention. For example, a colorstripe signal may be added to any AGC signal (e.g., as described in this application) for copy protection or content control. In another example, AGC and/or pseudo sync pulses are added to the overscan region (e.g., VBI). Another example is the addition of waveforms to enhance the effectiveness of the copy protection signal in the event of attenuation of the video signal caused by AGC effects (e.g., AGC pulses). To enhance effectiveness, the sync signal can also be narrowed to apply to the selected sync signal.

It should be appreciated that any of the methods, signals, waveforms, modifications, processes, and/or generators may be implemented in any combination of software, analog, and/or digital. For example, any of the methods, signals, or apparatuses may be provided for a device, such as a DVD player, a media player, a set-top box, a cellular phone, a camera, a video recorder, a player, a receiver, an integrated circuit, and/or a tuner. The control bits may also be used to control, enable, disable, and/or configure any of the signals or methods or devices. Default conditions may be included in any of the devices, whereby the output of any of these devices may include any of the previously described waveforms.

This disclosure is illustrative and not limiting. Further modifications will be apparent to those skilled in the art and are intended to fall within the scope of the appended claims.

Claims (31)

1. A method of improving playback of a copy protected video signal by reducing darkening effects in the video signal, wherein the copy protection signal includes Automatic Gain Control (AGC) pulses in video lines in a portion of an active or viewable television field or frame, the method comprising:

inserting or adding non-similar AGC pulses from one video line to another to improve playback in a television set or to reduce dimming or shutter effects.

2. The method of claim 1, wherein one or more of the AGC pulses may be deleted, blanked, and/or attenuated.

3. The method of claim 1, wherein the video signal includes synchronization pulses, the method comprising:

the pulse width and/or amplitude of the synchronization pulse is reduced.

4. The method of claim 1, wherein the non-similar AGC pulses are inserted or added into successive video lines.

5. The method of claim 1, wherein the non-similar AGC pulses are inserted or added to non-consecutive video lines.

6. A method of reducing dimming effects of a video signal in a video display device, comprising:

arranging non-similar Automatic Gain Control (AGC) signals in selected video lines in a portion of the video signals, at least two of the non-similar AGC signals being included in video lines present in a visible or visible portion of a television field or frame.

7. The method of claim 6, wherein one or more of the AGC pulses can be deleted, blanked, and/or attenuated.

8. The method of claim 6, wherein the video signal includes synchronization pulses, the method comprising:

the pulse width and/or amplitude of the synchronization pulse is reduced.

9. The method of claim 6, further comprising:

non-similar AGC pulses in a portion of the active television field or frame are sensed or read to produce a signal that can be used as a content control command.

10. A method for providing content control commands, wherein a video signal contains non-similar Automatic Gain Control (AGC) signals from one video line to another, the method comprising:

sensing or reading the non-similar AGC signal in a portion of an active field or frame, wherein sensing or reading the AGC signal produces a signal that can be used as the content control command.

11. The method of claim 10, wherein the AGC signal may include one or more AGC signals that are deleted, blanked, and/or attenuated.

12. The method of claim 10, wherein the video signal comprises a synchronization signal or pulse, the method further comprising:

the pulse width and/or amplitude of the selected synchronization signal or synchronization pulse is reduced.

13. A method of reducing the dimming effect of a video signal in a video display device, wherein the video signal comprises a trailing edge pulse of constant amplitude over a time interval indicative of an active field portion, the method comprising:

providing or synthesizing an anti-copy signal or content control signal comprising trailing edge pulses of non-similar pulse width and/or amplitude from one video line to another; and

wherein the copy protection signal or content control signal produces a reduced dimming effect in the video display device.

14. The method of claim 13, wherein the provided or synthesized copy protection signal or content control signal comprises horizontal and/or vertical synchronization pulses of reduced pulse width and/or reduced amplitude.

15. The method of claim 13, wherein one or more copy protection enhancement signals are synthesized or provided in the video signal, content control signal, copy protection signal, and/or the provided video signal.

16. The method of claim 13, further comprising:

level shifting selected horizontal synchronization pulses in the video signal.

17. The method of claim 13, further comprising:

negative going pulses and/or positive going pulses are added to the video signal.

18. The method of claim 13, further comprising:

adding a forward pulse or an Automatic Gain Control (AGC) pulse to the video signal; and

modulating the forward pulse and/or the AGC pulse.

19. The method of claim 18, wherein the modulated forward pulses and/or AGC pulses comprise any combination of modulation of amplitude, pulse coding, frequency, pulse width, and/or phase.

20. The method of claim 13, wherein negative going pulses or sync pulses or pseudo sync pulses are added, inserted, widened, narrowed, and/or positioned in a portion of the active field to reduce time base instability or image tearing when displaying the video signal on a monitor.

21. A method of providing at least a portion of a content control signal or a copy protection signal for a video signal, comprising:

adding or inserting a positive going pulse in a selected horizontal blanking interval, wherein the selected horizontal blanking interval includes a narrowed or modified sync pulse; and

varying the amplitude, phase, position, and/or duration of the forward pulse from one video line position to another video line position over at least a portion of the viewable range of the television field.

22. The method of claim 21, wherein a signal in the range of 100kHz to 30MHz is added to a portion of the video signal.

23. A method and apparatus as claimed in claim 22, wherein the signal is added to a portion of the vertical synchronisation signal in a portion or region of the vertical blanking interval.

24. The method of claim 21, wherein an enhancement signal is added, the enhancement signal comprising at least one of:

a modulated waveform extending below a blanking level for a period of time; a reduced trailing edge signal; a reduced leading edge signal; a dynamic gray to at least black signal; less than the blanking/black level of the sync level signal to a signal below the blanking level.

25. The method of claim 21, wherein the positive going pulse is located before the burst signal and/or within the first quarter or half of the trailing edge region.

26. A method of improving playback of a copy protected video signal by reducing darkening effects in the video signal, wherein the copy protected signal includes positive going pulses in the video lines of a television field or frame, the method comprising:

providing non-similar positive going pulses from one video line to another to provide improved playback of the copy protected video signal in a television set.

27. The method of claim 26, wherein the non-similar positive going pulses are provided into continuous or non-continuous video lines.

28. The method of claim 26, wherein the step of providing comprises:

varying the amplitude, phase, position and/or duration of the forward pulse from one video line position to another.

29. The method of claim 26, wherein the forward pulse is an Automatic Gain Control (AGC) pulse.

30. The method of claim 26, wherein the video signal includes synchronization pulses, the method comprising:

the amplitude and/or the pulse width of the synchronization pulse is varied.

31. The method of claim 26, further comprising:

sensing or reading the non-similar positive going pulses in a portion of the television field or frame to produce a signal that can be used as a content control command.