- 专利标题: Method and apparatus for disabling anti-copy protection system in video signals
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申请号: US08405482申请日: 1995-03-16
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公开(公告)号: USRE40689E1公开(公告)日: 2009-03-31
- 发明人: Ronald Quan , John F. Peruzzi
- 申请人: Ronald Quan , John F. Peruzzi
- 申请人地址: US CA Santa Clara
- 专利权人: Macrovision Corporation
- 当前专利权人: Macrovision Corporation
- 当前专利权人地址: US CA Santa Clara
- 代理机构: Morrison & Foerster LLP
- 主分类号: H04N5/76
- IPC分类号: H04N5/76 ; H04N5/93 ; H04N7/00 ; H04N7/167 ; H04N9/00 ; H04N9/79 ; G11B15/04 ; G11B19/04
摘要:
A method and apparatus for disabling the effect of copy-protect signals placed in a recording video signals which is based on differences in the characteristics of television and VCR circuitry. Copy-protect signals include pseudo-sync pulses and/or added AGC pulses in the blanking interval of a video signal. The specific method described includes altering the level of the video signal during the vertical blanking interval, e.g., level-shifting, so as to render the copy-protect copy protection signals ineffective to prevent in preventing unauthorized copying by a VCR. A circuit for achieving the method includes a sync separator for detecting the vertical blanking interval, pulse generating circuits for producing pulses of predetermined widths during this interval, and a summing circuit for summing the predetermined pulses with copy-protect signals thereby to shift their level. An alternative method includes increasing the effective frequency of the copy-protect signals during the vertical blanking interval so as to achieve attenuation and/or low-pass filtering in the VCR circuitry to there by render rendering the modified signals ineffective in preventing copying. A circuit for achieving this method includes pulse narrowing and/or pulse multiplication circuitry which effectively increased the high-frequency content of the pseudo-sync and/or AGC pulses.