Method for modifying a copy protected video signal with a negative amplitude pulse

• US 7,085,380 B2
• Filed: 09/26/2001
• Issued: 08/01/2006
• Est. Priority Date: 05/17/1993
• Status: Expired due to Fees

• Current Assignee: Macrovision Corporation (Adeia Inc.)
• Original Assignee: Macrovision Corporation (Adeia Inc.)
• Inventors: Quan, Ronald
• Primary Examiner(s): Barrón, Jr., Gilberto
• Assistant Examiner(s): Lanier, Benjamin E.
• Application Number:
  US09/965,345
• Publication Number:
  US 20020018564A1
• Time in Patent Office: 1,770 Days
• Field of Search: 380/204, 380/221
• US Class Current: 380/204
• CPC Class Codes: H04N 2005/91314 the copy protection signal being a pulse signal inserted in blanking intervals of the video signal, e.g. pseudo-AGC pulses, pseudo-sync pulses
• CPC Class Codes: H04N 2005/91371 the video color burst signal being modified
• CPC Class Codes: H04N 2005/91378 the video line number being modulated
• CPC Class Codes: H04N 2005/91385 the video frame number being modulated
• CPC Class Codes: H04N 5/913 for scrambling ; for copy protection
• CPC Class Codes: H04N 7/171 Systems operating in the amplitude domain of the television signal

Abstract

An enhancement is provided for a copy protection method that discourages copying (e.g., by video taping) of video signals. The enhancement adds negative amplitude pulses to the video signal at a location in the horizontal blanking interval “back porch” after the color burst. This enhances jitter when the copy protected signal is recorded on a VCR (video cassette recorder) and the recording is replayed, thereby making the recorded signal not suitable for viewing.

Claims

1. A method of modifying a copy protected video signal, wherein the copy protected video signal includes selected copy protection signals which cause a reduced amplitude in a recording of the copy protected video signal, the method comprising the act of:

adding a pulse having a selected negative amplitude to a selected position in a back porch region following a horizontal sync pulse wherein the copy protection of the video signal is enhanced by the added negative pulse.

2. The method of claim 1, wherein the negative pulse is added to selected active horizontal video lines of the video signal.

3. The method of claim 1, wherein the amplitude of the negative pulse is in the range of −

10 to −

20 IRE units, the negative pulse has a width in the range of 1 to 2 microseconds, and is positioned in the range of 1 to 2 microseconds after a color burst signal.

4. The method of claim 1, wherein the amplitude of the negative pulse is in the range of −

10 to −

20 IRE units.

5. The method of claim 1, wherein the negative pulse has a width in the range of 1 to 2 microseconds.

6. The method of claim 1, wherein the negative pulse is positioned in the range of 1 to 2 microseconds after a color burst signal in the back porch region.

13. The method of claim 1, wherein the negative pulse is amplitude modulated.

14. The method of claim 13, wherein the amplitude modulation includes turning off the negative pulse.

7. A method of modifying a copy protected video signal, wherein the copy protected video signal includes selected copy protection signals which cause a reduced amplitude in a recording of the copy protected video signal, the method comprising the act of:

adding a negative pulse of selected amplitude at a selected position in a back porch region following a horizontal signal pulse of the video signal wherein the negative pulse is part of the copy protection of the video signal which is enhanced by the added negative pulse.

8. The method of claim 7, wherein the negative pulse is added to selected horizontal video lines of the video signal.

9. The method claim 7, wherein the amplitude of the negative pulse is in the range of −

10 to −

20 IRE units, the negative pulse has a width in the range of 1 to 2 microseconds, and is positioned in the range of 1 to 2 microseconds after a color burst signal.

10. The method claim 7, wherein the amplitude of the negative pulse is in the range of −

10 to −

20 IRE units.

11. The method claim 7, wherein the negative pulse has a width in the range of 1 to 2 microseconds.

12. The method claim 7, wherein the negative pulse is positioned in the range of 1 to 2 microseconds after a color burst signal in the back porch region.