Method to synthesize video copy protection signals

• US 8,094,818 B2
• Filed: 02/09/2005
• Issued: 01/10/2012
• Est. Priority Date: 09/02/1998
• Status: Active Grant

• Current Assignee: Rovi Solutions Corporation (Adeia Inc.)
• Original Assignee: Rovi Solutions Corporation (Adeia Inc.)
• Inventors: Quan, Ronald
• Primary Examiner(s): Moorthy, Aravind K
• Application Number:
  US10/970,895
• Publication Number:
  US 20050117749A1
• Time in Patent Office: 2,526 Days
• Field of Search: 380/221, 380/206, 380/209, 380/210, 726/26, 713/163, 713/164, 713/167, 725/25, 725/31, 348/471
• US Class Current: 380/221
• 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 5/913 for scrambling ; for copy protection

Abstract

A method and apparatus for defeating copy protection signals in a video signal, and also for providing copy protection signals for a video signal, is disclosed. The defeat technique generally utilizes a particular pulse position shifting, modulation, etc., of AGC, normal sync and/or pseudo sync pulses to increase the separation between the pulses. Various embodiments are disclosed including selective shifting of the relative positions of either the sync/pseudo sync or AGC pulses, trimming portions of the sync/pseudo sync and/or the AGC pulses and narrowing of either the sync/pseudo sync and/or the AGC pulses, all to provide the selective position separation between the sync/pseudo sync and AGC pulses. The copy protection technique includes various embodiments for dynamically varying the sync/pseudo sync and AGC pulse separation by applying a modulation of the above position shifting, trimming and/or narrowing techniques over selected time periods to cycle from the copy protection condition to the copy protection defeat condition, back to the copy protection condition.

Claims

1. A method of synthesizing copy protection signals in a video signal employing horizontal sync pulses followed by respective AGC pulses, comprising:

replacing a portion of the horizontal sync pulse after the leading edge thereof with a selected gap voltage of selected duration to narrow the remaining portion of the horizontal sync pulse.

2. The method of claim 1 wherein the trailing edge of the narrowed horizontal sync pulse coincides with the beginning of the gap voltage of selected duration.

3. The method of claim 1 wherein the gap voltage duration between the narrowed horizontal sync pulse and the respective AGC pulse may change over time.

4. The method of claim 1 wherein the selected gap voltage is amplitude modulated.