Method and apparatus for recording scrambled video audio signals and playing back said video signal, descrambled, within a secure environment

• US 6,091,822 A
• Filed: 01/08/1998
• Issued: 07/18/2000
• Est. Priority Date: 01/08/1998
• Status: Expired due to Term

• Current Assignee: Macrovision Corporation (Adeia Inc.)
• Original Assignee: Macrovision Corporation (Adeia Inc.)
• Inventors: Brill, Gerow D., Mellows, Andrew B., Ryan, John O., Quan, Ronald, Wrobleski, William J.
• Primary Examiner(s): Swann, Tod R.
• Assistant Examiner(s): Callahan, Paul E.
• Application Number:
  US09/004,600
• Time in Patent Office: 922 Days
• Field of Search: 380/10, 380/13-15, 380/17, 380/20, 380/22, 380/23, 380/38, 380/52, 380/59, 386/46, 386/57, 386/79, 386/97
• US Class Current: 380/210
• 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 2005/91364 the video signal being scrambled
• CPC Class Codes: H04N 5/913 for scrambling ; for copy protection

Abstract

A technique is disclosed for preventing unauthorized playback of scrambled video/audio signals recorded on, for example, a video tape cassette, which technique includes several cooperating processes and apparatus which further prevent the playback of recorded video/audio when the playback apparatus is in a still or pause mode of operation. The technique includes selected combinations of processes of inverting and re-clamping the luminance component of the video signal just prior to FM modulation; blanking an overscan portion, or portions, of the video signal and adding a video retrace signal to the overscan portion(s); inverting the normal control track signal and position modulating the normally unused edge; and selectively scrambling the audio signal and recording the scrambled audio signal in an audio track or in a Hi-Fi track. A selected user specific authorization code is recording in and recovered from the audio track. The recorded scrambled video/audio signal is recovered via a modified combo VCR/TV unit with no external video/audio jacks, which reverses the scrambling processes mentioned above, but only if the descrambling apparatus is authorized by having the proper recovered authorization code.

Claims

1. A method of scrambling a recorded video and audio signal comprising the steps of:

inverting a luminance component of the video signal just prior to FM modulation of the luminance component within a data recorder;

adding a video retrace command to an overscan portion of said video signal;

inverting a normal control track signal having normally used and normally unused edges;

providing an authorization signal identifying a specific customer; and

recording the scrambled video signal and the authorization signal onto a recording medium.

2. The method of claim 1 including the step of:

position modulating the normally unused edges of the reversed control track signal.

3. The method of claim 1 including the step of:

blanking the overscan portion of the video signal prior to performing the step of adding.

4. The method of claim 3 wherein the step of adding includes inserting a white level pulse into the blanked overscan portion of the video signal, which pulse overlaps the beginning of the active video signal.

5. The method of claim 3 wherein the step of adding includes inserting a white level pulse into the blanked overscan portion of the video signal at the end of the active video signal.

6. The method of claim 3 wherein the step of adding includes inserting white level pulses at selected beginnings and ends of selected lines of the video signal, with the white level pulses alternating in position at the beginning and end of each selected line and from field to field.

7. The method of claim 1 including the steps of:

selectively scrambling the audio signal;

inserting the authorization signal in the scrambled audio signal; and

recording the scrambled audio signal with the authorization signal in an audio track in the recording medium.

8. The method of claim 7 including the steps of:

providing a pilot tone signal of selected frequency; and

inserting the authorization and pilot tone signals in the scrambled and recorded audio signal.

9. The method of claim 7 wherein the step of scrambling the audio signal includes fixed or variable frequency shifting of the audio signal baseband frequencies to a selected frequency spectrum above the baseband frequencies.

10. The method of claim 1 including the step of:

separating the luminance component from the video signal prior to the step of inverting the luminance component.

11. The method of claim 1 including the steps of:

scrambling the audio signal by fixed or variable frequency shifting of the audio signal to a higher frequency spectrum;

recording the shifted audio signal in a Hi-Fi track in the recording medium together with the scrambled video signal; and

recording the authorization signal in an audio track in the recording medium.

12. The method of claim 1 including the steps of:

separating a chrominance component from the video signal prior to scrambling the video signal; and

exchanging portions of the chrominance component to provide a scrambled chrominance component for recording onto the recording medium.

13. The method of claim 1 including the steps of:

separating a chrominance component from the video signal prior to scrambling the video signal; and

exchanging the upper chroma side band with the lower chroma side band of the chrominance component to provide a scrambled chrominance component for recording onto the recording medium.

14. A method of descrambling previously scrambled and recorded video and audio signals when played back from a recording medium in a data recorder, comprising the steps of:

detecting an authorization signal from data recorded in the recording medium and providing authorization for playing back the descrambled video signal;

re-inverting a previously inverted luminance component of the video signal just after FM demodulation of the luminance component within the data player to enable descrambling the video signal;

blanking the video signal in a selected overscan portion of the video signal to remove any pulses in the overscan portion;

re-inverting a previously inverted control track signal played back from a control track in the recording medium; and

playing back the descrambled video signal.

15. The method of claim 14 including the steps of:

descrambling the audio signal when authorized by the authorization signal; and

playing back the descrambled audio signal with the descrambled video signal.

16. The method of claim 15 including the steps of:

providing a customer specific digital code in the scrambled audio signal, which code corresponds to the authorization signal;

comparing the digital code in the audio signal with the code specific to the customer; and

providing control signals authorizing the play back of the descrambled video and audio signals if the compared codes match.

17. The method of claim 16 wherein:

the control signals include an audio mute/decode/clear signal which provides the steps of;

preventing passage of the descrambled audio signal if unauthorized;

allowing passage of the descrambled audio signal if authorized; and

bypassing the audio signal around the descrambling process if the audio signal was not scrambled.

18. The method of claim 16 wherein:

the control signals include a decode command which provides the steps of;

reversing connections to the modified control track signal when authorized to provide said step of inverting the played back modified control track signal; and

routing the luminance component through an inverter circuit when authorized to provide said step of inverting the played back luminance component.

19. The method of claim 16 wherein:

the control signals include a video/blank mute signal which provides the steps of;

blanking the video signal in the selected overscan portion thereof when authorized; and

preventing or allowing passage of the descrambled video signal when unauthorized or authorized, respectively.

20. The method of claim 14 including the steps of:

providing white level pulses in selected overscan portions of the video signal; and

turning off the video signal in the selected overscan portions to provide the step of blanking the video signal.

21. The method of claim 14 wherein the scrambled audio signals have been recorded in a Hi-Fi track in the recording medium, including the steps of:

recovering the shifted audio signal from the Hi-Fi track in the recording medium; and

descrambling the recovered audio signal when authorized by the authorization signal.

22. The method of claim 21 wherein the authorization signal is recorded in a linear audio track in the recording medium, including the step of:

recovering the authorization signal from the linear audio track to enable the steps of descrambling the audio and video signals.

23. A method of scrambling, recording and subsequently descrambling and playing back a video/audio signal, wherein the recording includes a synchronization control signal in a control track of a recording medium for use in controlling the video/audio signal playback, comprising the steps of:

adding white level pulses to selected overscan portions of the video signal;

FM modulating the video signal during the recording thereof;

inverting a luminance component of the video signal including the added white level pulses just prior to FM modulation of the luminance component;

detecting the inverted white level pulses as synchronizing pulses during the recording to cause instabilities and corresponding scrambling of the video signal;

providing authorization data identifying a specific customer;

recording the scrambled video signal and the authorization data in the recording medium;

detecting the authorization data when subsequently playing back the recorded scrambled video signals;

re-inverting the luminance component and the white level pulses of the played back scrambled video signal when authorized by the detected authorization data;

blanking the white level pulses added to the selected overscan portion of the video signal to remove the pulses when authorized by the detected authorization data;

wherein the steps of re-inverting and blanking provide descrambling of the video signal; and

playing back the descrambled video signal when authorized by the detected authorization data of the re-inverting and blanking steps.

24. The method of claim 23 including the steps of:

scrambling the audio signal by selectively shifting it from an original frequency spectrum to a higher frequency spectrum;

wherein the step of recording includes recording the audio signal in the recording medium;

descrambling the audio signal by shifting it back to the original frequency spectrum; and

playing back the descrambled audio signal along with the descrambled video signal when authorized.

25. The method of claim 24 wherein:

the step of recording includes recording the authorization data with the audio signal in an audio track; and

the steps of descrambling and playing back include recovering the authorization data, along with the scrambled audio signal, from the audio track, to enable the descrambling of the video and audio signals.

26. The method of claim 24 wherein:

the step of recording includes recording the scrambled audio signal in a Hi-Fi track in a recording medium; and

the steps of descrambling and playing back include recovering the scrambled audio signal from the Hi-Fi track, and descrambling the recovered audio signal by selectively shifting it back to the original frequency spectrum.

27. The method of claim 24 including the steps of:

inserting a pilot tone in the audio signal during the video/audio scrambling process;

detecting the pilot tone during the playback of the descrambled video/audio signals to determine the presence of time base errors therein; and

correcting the timing of the playback process to remove the time base errors.

28. The method of claim 23 including the steps of:

separating a chrominance component from the video signal prior to scrambling the video signal;

exchanging the upper chroma sideband with the lower chroma sideband of the chrominance component prior to the step of recording to further scramble the video signal; and

upon playback, exchanging the chroma sidebands back to their original relationship to reconstitute the chrominance component of the video signal when authorized.

29. The method of claim 23 including the steps of:

inverting the synchronization control track signal during the video scrambling to switch the functions of the normally unused edges of the control track signal with the normally used edges thereof; and

re-inverting the inverted control track signal when authorized by the detected authorization data during the playback of the descrambled video signal.

30. The method of claim 29 including the steps of:

position modulating the normally unused edges of the inverted synchronization control track signal during the step of inverting it; and

position demodulating the modulated edges of the re-inverted control track signal during the step of re-inverting it.

31. Apparatus for scrambling, recording in a recording medium, and subsequently descrambling on playback, video/audio signals, comprising:

means receiving the video signal for adding white level pulses to a selected overscan portion of the video signal to provide a modified video signal,

means for FM modulating the modified video signal during the recording process;

means disposed prior to the FM modulating means for inverting the luminance component and also the added white level pulses of the modified video signal before the FM modulation;

means integral with the recording process for detecting the inverted white level pulses as synchronizing pulses to cause horizontal instabilities and scrambling of the video signal;

means for providing authorization data indicative of a specific user;

means for recording the modified and FM modulated video signal and the authorization data on the recording medium;

means for detecting the authorization data in the recording medium during the playback process and for providing an authorization signal indicative of the specific user;

means for FM demodulating the played back video signal;

means for inverting the FM demodulated video signal and white level pulses in response to the authorization signal;

means for removing the white level pulses from the selected overscan portion of the played back video signal, and

means for displaying and recovering the descrambled video signals when authorized by the authorization signal.

32. The apparatus of claim 31 including:

means receiving the audio signal for scrambling the audio signal;

means for recording the scrambled audio signal on the recording medium; and

means for descrambling the recorded scrambled audio signal during the playback process.

33. The apparatus of claim 32 wherein:

the means for recording includes means for recording the scrambled audio signal and the authorization data in an audio track in the recording medium; and

the means for descrambling includes means for recovering the authorization data and the audio signal from the audio track and for descrambling the audio and video signals in response to the recovered authorization data.

34. The apparatus of claim 33 wherein the means for scrambling the audio signal and for recording the audio signal with the authorization data includes:

frequency spectrum shifting means for shifting the audio signal baseband frequencies to a selected frequency spectrum above the baseband frequencies;

means for providing a use specific authorization code corresponding to the authorization data;

means for modulating the authorization code with a carrier signal; and

means for adding the modulated authorization code to the audio signal.

35. The apparatus of claim 32 wherein:

the means for recording includes means for recording the scrambled audio signal in a Hi-Fi track in the recording medium;

the means for descrambling the audio signal includes frequency shifting means receiving a recovered audio signal from the Hi-Fi track, and for descrambling the recovered audio signal by a frequency shifting process.

36. The apparatus of claim 32 wherein the means for scrambling the audio signal and for adding the authorization data includes:

means for adding a pilot tone to the authorization data added to the audio signal; and

means receiving the played back audio signal for detecting the pilot tone to detect and correct time base errors in the audio signal.

37. The apparatus of claim 31 including:

means for separating a chrominance component from the video signal;

means for exchanging the upper chroma sideband with the lower chroma sideband of the chrominance component prior to recording in the recording medium;

means in the playback process for exchanging the chroma sidebandsphase back to their original relationship to reconstitute the descrambled video signal for playback.

38. The apparatus of claim 31 including:

means disposed prior to the means for adding white level pulses for blanking the selected overscan portion prior to adding the white level pulses; and

said means for removing the white level pulses comprises blanking means for blanking the descrambled video signal when playback is authorized.

39. The apparatus of claim 31 wherein the video signal includes lines of active video, wherein the means for adding inserts white level pulses at selected beginnings and ends of selected lines of the lines of active video, with the white level pulses alternating in position at the beginning and end of each selected line and from field to field.

40. The apparatus of claim 31 wherein a control track signal of normally used and normally unused edges is recorded in the recording medium, including:

means for inverting the control track signal;

means for position modulating the normally unused edges of the inverted control track signal to enhance the scrambling of the video signal;

means for position demodulating the modulated edges of the inverted control track signal; and

means for re-inverting the played back demodulated control track signal.

41. A method of scrambling recorded video signal wherein the recording includes a normal control track signal in a control track, comprising the steps of:

inverting the normal control track signal in the control track during the scrambling to provide an inverted control track signal in which the functions of the normally unused edges of the normal control track signal are switched with the normally used edges thereof; and

recording the inverted control track signal in the control track of the recording.

42. The method of claim 41 including descrambling the scrambled video signal during subsequent playback thereof, including the step of:

re-inverting the inverted control track signal during the descrambling to recover the normally used and unused edges thereof; and

playing back the descrambled video signal when authorized.

43. The method of claim 41 including the step of:

position modulating the normally unused edges of the inverted control track signal during the step of inverting it.

44. The method of claim 43 including descrambling the scrambled video signal during subsequent playback thereof, including the steps of:

re-inverting the inverted control track signal during the playback and descrambling to recover the normally used and unused edges thereof; and

position demodulating the modulated edges of the re-inverted control track signal during the playback and descrambling.

45. A method of scrambling a video signal formed of lines and fields of video, to prevent viewing of the video signal as well as prevent a viewable reproduction of a subsequent recording of the video signal, comprising the steps of:

adding white level pulses at selected beginnings and ends of selected lines of video, with the white level pulses alternating in position at the beginning and end of each selected line and from field to field of video;

inverting the video content of the video signal to likewise invert the white level pulses; and

detecting the inverted white level pulses as synchronizing pulses during the recording to cause horizontal instability in the lines of video.

46. The method of claim 45 including:

FM modulating the lines of video during the recording of the video signal; and

wherein the step of inverting the video content is performed just prior to the step of FM modulating.

47. A method of scrambling, recording and subsequently descrambling and playing back a video signal having luminance and chrominance components, comprising the steps of:

separating the chrominance component from the video signal prior to scrambling the video signal;

exchanging the upper chroma sideband with the lower chroma sideband of the chrominance component prior to recording the thusly scrambled video signal; and

upon playback, re-exchanging the upper and lower chroma sidebands back to their original relationship to reconstitute the chrominance component of the video signal.