Method and apparatus for copy protection detection in a video signal

• US 8,774,601 B2
• Filed: 09/10/2009
• Issued: 07/08/2014
• Est. Priority Date: 05/21/1999
• Status: Active Grant

• Current Assignee: ATI Technologies ULC (Advanced Micro Devices, Inc.)
• Original Assignee: ATI Technologies ULC (Advanced Micro Devices, Inc.)
• Inventors: Rinaldi, Antonio
• Primary Examiner(s): Zhao, Daquan
• Assistant Examiner(s): HASAN, SYED Y
• Application Number:
  US12/557,245
• Publication Number:
  US 20090324198A1
• Time in Patent Office: 1,762 Days
• Field of Search: 386/252, 386/E5.004, 348/465, 348/545, 348/505, 348/E9.031, 360/60, 380/201
• US Class Current: 386/252
• 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 detecting copy protection included in an input video signal is described. Two types of copy protection are particularly addressed, including techniques that imbed copy protection pulses and copy protection phase flips in the video signal. A method for preserving copy protection is also presented, where the input video signal is first examined to determine if copy protection has been included in the input video signal. The input video signal then converted to component video data, which removes any copy protection present. An output video signal is then generated from the component video data, and when it was determined that the input video signal includes copy protection, the copy protection is recreated in the output video signal.

Claims

1. A colorburst phase flip detection circuit, comprising:

a phase flip detection block that receives a demodulated chroma signal, wherein the phase flip detection block detects when a phase flip is included in a colorburst portion of the chroma signal, wherein the phase flip detection block checks each line of each frame of the demodulated chroma signal for phase flips, wherein the phase flip detection block sets a flip detected indication each time a line is found to include a phase flip, wherein the flip detected indication is cleared based on a line boundary indication;

a field counting block operably coupled to the phase flip detection block, wherein the field counting block determines a field count equal to a number of phase flips per field based on the flip detected indication and a field boundary indication; and

an interval counting block operably coupled to the phase flip detection block, wherein the interval counting block determines an interval count equal to a number of consecutive lines having phase flips based on the flip detected indication.

2. The colorburst phase flip detection circuit of claim 1, wherein the phase flip detection block detects when a phase flip is included by comparing an integrated absolute value of the demodulated chroma signal with the demodulated chroma signal.

3. A method for detecting phase flip copy protection in an input video signal, comprising:

demodulating the input video signal to produce demodulated chroma signal that includes a colorburst signal for each line of the input video signal;

performing an absolute value function on the demodulated chroma signal to produce an absolute value chroma signal that includes an absolute value colorburst signal;

comparing phase of the colorburst signal with phase of the absolute value colorburst signal to determine if a phase flip has occurred for each line in the input video signal;

determining a total number of phase flips per display field; and

determining an interval number of phase flips, wherein each occurrence of phase flipping occurs in groups of sequential lines, wherein the interval number indicates a number of lines per group,

wherein the total number of phase flips per display field and the interval number of phase flips are used in the regeneration of the phase flip copy protection in the input video signal.

4. The method of claim 3, wherein comparing phase of the colorburst signal with phase of the absolute value colorburst signal further comprises:

integrating the absolute value colorburst signal to produce an integrated colorburst value; and

comparing the integrated colorburst value with values in the colorburst signal.