Motion video signal processing for recording or reproducing – Local trick play processing – With randomly accessible medium
Reexamination Certificate
1999-09-13
2003-07-29
Chevalier, Robert (Department: 2615)
Motion video signal processing for recording or reproducing
Local trick play processing
With randomly accessible medium
C386S349000, C360S060000
Reexamination Certificate
active
06600873
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a method and apparatus for preventing the copying of a video program. More particularly, it relates to detecting, a modified color burst signal in even a single television line of a video signal to cause disabling of the recording portion of a video recording device when the modified video signal is detected.
Various apparatuses and methods have been developed for modifying a video signal so that a normal color picture may be produced by a television receiver receiving the modified video signal, but that video recording of the modified video signal is impaired. That is, a video picture produced from the video signal as recorded on a video tape recorder is altered so that it makes unacceptable viewing.
U.S. Pat. No. 4,631,603 ('603) entitled “Method and Apparatus for Processing a Video Signal so as to Prohibit the Making of Acceptable Video Tape Recordings Thereof,” which is incorporated by reference, discloses such a method and apparatus. It describes adding ordered pairs of pseudo-sync pulses and white pulses during the vertical blanking interval. These pulse pairs act in concert to confuse the automatic gain system of a video cassette recorder (VCR), leading to generally unviewable pictures.
U.S. Pat. No. 4,907,093 ('093) entitled “Method and Apparatus for Preventing The Copying of a Video Program,” which is incorporated by reference, discloses a method and apparatus for detecting the ordered pairs of pseudo-sync pulses and white pulses described in the '603 patent and disabling the recording function of a video cassette recorder. The '093 patent discloses several detection methods.
U.S. Pat. No. 4,577,216, “Method and Apparatus For Processing a Video Signal,” issued Mar. 18, 1986 and incorporated by reference, discloses modifying a color video signal to inhibit the making of acceptable video recordings thereof A conventional television receiver produces a normal color picture from the modified signal. However, the resultant color picture from a subsequent video tape recording shows variations in the color fidelity that appear as bands or stripes of color error. Colloquially the modifications are called the “Colorstripe™” system or the “Colorstripe™” process. The term “Colorstripe” is a trademark of the assignee of this application. Commercial embodiments of the teachings of this patent typically limit the number of video lines per field having the induced color error or color stripes.
Color video signals (both in the NTSC and PAL color television standard systems) include what is called a color burst. The Colorstripe™ system modifies the color burst. The suppression of the color subcarrier signal at the television (TV) transmitter requires that the color TV receiver include (in NTSC) a 3.58 MHz oscillator which is used during demodulation to reinsert the color subcarrier signal and restore the color signal to its original form. Both the frequency and phase of this reinserted subcarrier signal are critical for color reproduction. Therefore, it is necessary to synchronize the color TV receiver's local 3.58 MHz oscillator so that its frequency and phase are in step with the subcarrier signal at the transmitter.
This synchronization is accomplished by transmitting a small sample of the transmitter's 3.58 MHz subcarrier signal during the back porch interval of the horizontal blanking pulse.
FIG. 1
shows one horizontal blanking interval of an NTSC color signal. The horizontal sync pulse, the front porch and blanking interval duration are essentially the same as that for black and white TV. However, during color TV transmission (both broadcast and cable) 8 to 10 cycles of the 3.58 MHz subcarrier that is to be used as the color sync signal are superimposed on the back porch. This color sync signal is referred to as the “color burst” or “burst”. The color burst peak-to-peak amplitude (40 IRE for NTSC TV as shown) is the same amplitude as the horizontal sync pulse.
FIG. 1A
shows an expanded view of a part of the waveform of
FIG. 1
including the actual color burst cycles. During the color TV blanking intervals, such a color burst is transmitted following each horizontal sync pulse.
In one commercial embodiment of the Colorstripe™ process, no color burst phase (stripe) modification appears in the video lines that have a color burst signal during the vertical A blanking interval. These are lines
10
to
21
in an NTSC signal and corresponding lines in a PAL signal. The color burst modifications occur in bands of four to five video lines of the viewable TV field followed by bands of eight to ten video lines without the color burst modification. The location of the bands is fixed (“stationary”) field-to-field. This Colorstripe™ process has been found to be quite effective for cable television, especially when combined with the teachings of U.S. Pat. No. 4,631,603 also invented by John O. Ryan and incorporated herein by reference.
In NTSC TV, the start of color burst is defined by the zero-crossing (positive or negative slope) that precedes the first half cycle of subcarrier (color burst) that is 50% or greater of the color burst amplitude. It is to be understood that the Colorstripe™ process shifts the phase of the color burst cycles relative to their nominal (correct) position, illustrated for example in FIG.
1
A. An example of a phase shifted color burst is shown in FIG.
1
B. The amount of phase shift shown in
FIG. 1B
is 180° (the maximum possible) over the entire color burst.
Further, the amount of phase shift in the Colorstripe™ process can vary from e.g. 20° to 180°; the more phase shift, the greater the visual effect in terms of color shift. In a Colorstripe™ process for PAL TV, a somewhat greater phase shift (e.g. 40° to 180°) is used to be effective.
FIG. 1C
illustrates a color burst signal which is partially modified, that is, is partially phase shifted, to prevent making a recording of the associated video signal. In an exemplary NTSC embodiment, such as disclosed in the PCT Application Number US96/17719 incorporated by reference, a system called Advanced Switched Burst (ASB) has the capability of programming various combinations of partially modified color burst signals.
FIG. 1C
illustrates one of such combinations, by way of example only, wherein the color burst envelope comprises three zones. Zone
1
(burst start) begins 4.96 microseconds (&mgr;secs) after the leading edge of horizontal sync. Zone
1
ends 1.48 &mgr;secs after normal burst start. Zone
2
begins and ends at the end of Zone
1
. In this particular embodiment, there is no Zone
2
per se. Zone
3
begins after the Zone
2
point and extends 1.48 &mgr;secs to the end of burst. Therefore, in this particular embodiment, the color burst has a width of 4.96 &mgr;secs. The Zone
1
area will contain modified (inverted 180°) subcarrier. Normal phase subcarrier is used in Zone
2
(zero duration) and Zone
3
.
Although three zones are illustrated in
FIG. 1C
by way of example, the color burst may be partially phase shifted using other numbers of zones, e.g. two, etc., and phase shifting may be applied to various ones of the zones.
Other variations of the Colorstripe™ process are described in the following provisional applications: Serial No. 60/010015 by William J. Wrobleski entitled An Improved Method And Apparatus For Modifying The Color Burst To Prohibit Video Tape Recording, Serial No. 60/010779 by William J. Wrobleski, entitled An Advanced Color Burst Method And Apparatus For Modifying The Color Burst To Prohibit Videotape Recording, Serial No. 60/014246 by William J. Wrobleski, entitled A Method And System Of Copy Protection Using An Advanced And Split Color Burst. The three applications were combined in a U.S. non-provisional patent application which issued Feb. 4, 2003 as U.S. Pat. No. 6,516,132.
Methods and apparatuses for defeating the effects of the color burst modifications of the '216 patent and others are described in U.S. Pat. No. 4,626,890 entitled “Method and Apparatus for Removing Phase Modulation
Brill Gerow D.
Ryan John O.
Almeida G.
Chevalier Robert
Macrovision Corporation
LandOfFree
Method and apparatus for detecting modified color burst... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for detecting modified color burst..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for detecting modified color burst... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3071357