Scrambling type method and apparatus for video transmission/receipt

• US 6,035,044 A
• Filed: 11/06/1997
• Issued: 03/07/2000
• Est. Priority Date: 11/07/1996
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Itoi, Satoshi
• Primary Examiner(s): Swann, Tod R
• Assistant Examiner(s): CODDINGTON, TREVOR Q
• Application Number:
  US08/964,374
• Time in Patent Office: 852 Days
• Field of Search: 380/10, 380/9, 380/14, 380/59
• US Class Current: 380/210
• CPC Class Codes: H04N 21/23476 by partially encrypting, e.g. encrypting the ending portion of a movie
• CPC Class Codes: H04N 21/8453 by locking or enabling a set of features, e.g. optional functionalities in an executable program
• CPC Class Codes: H04N 7/1675 Providing digital key or authorisation information for generation or regeneration of the scrambling sequence pseudo-random number generators in general G06F7/58

Abstract

A scrambling type video transmitting/receiving method feasible for digital television broadcasting and an apparatus therefor are disclosed. A video transmitter executes soft scrambling with an original video signal before compressing it and then sends the softly scrambled video signal. If a video receiver descrambles the scrambled data with a scramble decoder (descrambler), a subscriber having the receiver can enjoy complete video/audio data. However, when an unauthorized person lacking the scramble decoder decodes the descrambled data, the person is allowed to see only some patterns included in a picture. This will successfully encourage the unauthorized person to make subscription so as to enjoy the complete video/audio data.

Claims

1. A method of transmitting/receiving video, comprising:

compressing an original video signal by orthogonal transform, quantization, and variable-length encoding performed in this order, said variable-length encoding step including;

dividing a quantized video signal into high frequency components and low frequency components;

soft scrambling said high frequency components but not said low frequency components in an individual orthogonal transform block, said soft scrambling step including transforming said low frequency components in accordance with an original variable-length coding table to produce a first scrambled signal and then transforming said first scrambled signal in accordance with another variable-length coding table having a same number of bits to produce a second scrambled signal;

combining said second scrambled signal and said low frequency components into a combined signal; and

transmitting said combined signal as a signal to be transmitted.

2. A method as claimed in claim 1, wherein said soft scrambling is effected such that if a receiver does not descramble the compressed video signal, the original video signal is reproduced to a degree allowing only some patterns to be recognizable.

3. A method as claimed in claim 2, wherein the signal to be transmitted is received as a received signal, the received signal is subjected to soft descrambling inverse to said soft scrambling to thereby reconstruct the compressed video signal, and a reconstructed video signal is expanded to thereby reproduce the original video signal.

4. A method as claimed in claim 1, wherein the signal to be transmitted is received as a received signal, the received signal is subjected to soft descrambling inverse to said soft scrambling to thereby reconstruct the compressed video signal, and a reconstructed video signal is expanded by variable-length coding, quantization and inverse orthogonal transform to thereby reproduce the original video signal.

5. A method as claimed in claim 1, wherein for said soft scrambling, all components are dealt with as high frequency components.

6. A method as claimed in claim 1, wherein the low frequency components not scrambled are only DC components.

7. A method as claimed in claim 1, wherein the Low frequency components not scrambled comprise a combination of DC components and a preselected number of runs/levels determined from a low frequency side.

8. A method as claimed in claim 1, wherein the high frequency components scrambled comprise a combination of a preselected number of runs/levels determined from a high frequency side toward a low frequency side of an end-of-block side.

9. A method as claimed in claim 1, wherein a distance between the original table and the other table is determined on the basis of scrambled data.

10. A method of transmitting/receiving a compressed video signal produced by compressing an original video signal, comprising steps of:

soft scrambling an original video signal in accordance with a first scrambling table to produce a first scrambled signal;

soft scrambling said first scrambled signal in accordance with a second scrambling table to produce a second scrambled signal, said first scrambling step and said second scrambling step being performed before compression;

compressing said second scrambled signal to form a compressed video signal; and

transmitting the compressed video signal.

11. A method as claimed in claim 10, wherein said soft scrambling steps are effected such that if a receiver does not descramble the compressed video signal, the original video signal is reproduced to a degree allowing only some patterns to be recognizable.

12. A method as claimed in claim 10, wherein at least one of said soft scrambling steps comprises rearranging preselected unit blocks of the original video signal within a preselected group in a particular order.

13. A method as claimed in claim 10, wherein at least one of said soft scrambling steps comprises rearranging picture data within a group of pictures i a particular order.

14. A method as claimed in claim 10, wherein at least one of said soft scrambling steps comprises rearranging slice data within a picture in a particular order.

15. A method as claimed in claim 10, wherein at least one of said soft scrambling steps comprises rearranging macroblock data within a slice in a particular order.

16. A method as claimed in claim 10, wherein said soft scrambling steps comprise two of rearranging picture data within a group of pictures in a particular order, rearranging slice data within a picture in a particular order, and rearranging macroblock data within a slice in a particular order.

17. A method as claimed in claim 10, wherein the compressed video signal is received as a received signal, the received signal is expanded to thereby reconstruct a scrambled signal undergone said soft scrambling steps, and the descrambled signal is subjected to two soft descrambling steps respectively inverse to said soft scrambling steps to thereby reproduce the original video signal.

18. A method of transmitting/receiving a compressed video signal produced by compressing an original video signal, comprising:

main soft scrambling the original video signal before compression to produce a first scrambled signal, and then

auxiliary soft scrambling the first scrambled signal at a same time the first scrambled signal is encoded by a variable-length encoder to thereby send a resulting compressed video signal as a signal to be transmitted.

19. A method as claimed in claim 18, wherein compression of the first scrambled signal includes subjecting the first scrambled signal to orthogonal transform, quantization and variable-length coding in this order to thereby produce the compressed video signal, wherein said main soft scrambling step comprises rearranging unit blocks within a preselected group in a particular order, and wherein said auxiliary soft scrambling step comprises scrambling high frequency components in an individual orthogonal transform block, but no scrambling low frequency components.

20. A method as claimed in claim 18, when said main scrambling comprises a combination of at least two of rearranging picture data within a group of pictures in a particular order, rearranging slice data within a picture in a particular order, and rearranging macroblock data within a slice in a particular order.

21. A method as claimed in claim 18, wherein auxiliary soft descrambling inverse to said auxiliary soft scrambling is effected with the received signal to thereby reconstruct the compressed video signal, a reconstructed compressed video signal is expanded to reconstruct a signal undergone said main soft scrambling, and then main soft descrambling inverse to said main soft scrambling is effected with a reconstructed signal undergone said main soft scrambling to thereby reproduce the original video signal.

22. A video transmitter/receiver comprising:

compressing means for compressing an original video signal to thereby output a compressed video signal;

scrambling means, within said compressing means, for soft scrambling said original video signal at a same time a variable-length encoder within said compressing means encodes said original video signal; and

transmitting means for sending a resulting signal as a signal to be transmitted.

23. A video transmitter/receiver as claimed in claim 22, wherein said compressing means comprises:

orthogonal transforming means for executing orthogonal transform with the original video signal to thereby output a transformed signal;

quantizing means for quantizing the transformed signal to thereby output a quantized signal; and

variable-length coding means for executing variable-length coding with the quantized signal to thereby output the compressed video signal;

said scrambling means effecting sad soft scrambling by scrambling, in an individual orthogonal transform block, high frequency components, but not scrambling low frequency components.

24. A video transmitter/receiver as claimed in claim 22, further comprising:

descrambling means for executing soft descrambling inverse to said soft scrambling with a received signal, which is the signal to be transmitted, to thereby reconstruct the compressed video signal; and

expanding means for expanding a reconstructed compressed video signal output from said descrambling means to thereby reproduce the original video signal.

25. A video transmitter/receiver comprising:

a first scrambling means for soft scrambling an original video signal in accordance with a first scrambling table to thereby output a first scrambled signal;

a second soft scrambling for soft scrambling said first scrambled signal in accordance with a second scrambling table to produce a second scrambled signal;

compressing means for compressing the second scrambled signal to thereby output a compressed video signal; and

a transmitting means for transmitting the compressed video signal.

26. A video transmitter/receiver as claimed in claim 25, wherein at least one of said first and second scrambling means rearranges unit blocks within a preselected group in a particular order.

27. A video transmitter/receiver as claimed in claim 26, wherein said compressing means comprises:

orthogonal transforming means for executing an orthogonal transform with the second scrambled signal to thereby output a transformed signal;

quantizing means for quantizing the transformed signal to thereby output a quantized signal; and

variable-length coding means for executing variable-length coding with the quantized signal to thereby output the compressed video signal.

28. A video transmitter/receiver as claimed in claim 25, further comprising:

expanding means for expanding a received signal, which is the signal to be sent, to thereby output the second scrambled signal; and

descrambling means for executing soft descrambling of said second scrambled signal output from said expanding means, said descrambling being inverse to said soft scrambling performed by said first scrambling means and said second scrambling means to thereby reproduce the original video signal.

29. A video transmitter/receiver comprising:

main scrambling means for executing main soft scrambling of an original video signal to thereby output a main scrambled signal;

compressing means for compressing the main scrambled signal to thereby output a compressed video signal;

auxiliary scrambling means for executing auxiliary soft scrambling at a same time a variable-length encoder encodes the main scrambled signal to thereby output a compressed auxiliary scrambled signal; and

transmitting means for transmitting the auxiliary scrambled signal.

30. A video transmitter/receiver as claimed in claim 29, wherein said main scrambling means executes said main soft scrambling by rearranging preselected unit blocks within a preselected group in a particular order.

31. A video transmitter/receiver as claimed in claim 30, wherein said compressing means comprises:

orthogonal transforming means for executing orthogonal transform with the main scrambled signal to thereby output a transformed signal;

quantizing means for quantizing the transformed signal to thereby output a quantized signal; and

variable-length coding means for executing variable-length coding with the quantized signal to thereby output the compressed video signal;

said auxiliary scrambling means executing said auxiliary soft scrambling by scrambling, within an individual orthogonal transform block, high frequency components, but not scrambling low frequency components.

32. A video transmitter/receiver as claimed in claim 31, wherein said main scrambling means executes at least one of rearranging picture data within a group of pictures in a particular order, rearranging slide data within a picture in a particular order, and rearranging macroblock data within a slice in a particular order.

33. A video transmitter/receiver as claimed in claim 29, further comprising:

auxiliary descrambling means for executing auxiliary descrambling inverse to said auxiliary soft scrambling with a received signal, which is the signal to be transmitted, to thereby reconstruct the compressed video signal;

expanding means for expanding a reconstructed compressed video signal output from said auxiliary descrambling means to thereby reconstruct the main scrambled signal; and

main descrambling means for executing main soft descrambling inverse to said main soft scrambling with a reconstructed main scrambled signal output from said expanding means to thereby reproduce the original video signal, wherein auxiliary soft descrambling inverse to said auxiliary soft scrambling is effected with the received signal to thereby reconstruct the compressed video signal, a reconstructed compressed video signal is expanded to reconstruct a signal undergone said main soft scrambling, and then main soft descrambling inverse to said main soft scrambling is effected with a reconstructed signal undergone said main soft scrambling to thereby reproduce the original video signal.