Digital security system

• US 7,949,131 B2
• Filed: 12/19/2005
• Issued: 05/24/2011
• Est. Priority Date: 12/19/2005
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: SigmaTel Incorporated (NXP Semiconductors NV)
• Inventors: Shkolnyy, Konstantin, Torrini, Antonio
• Primary Examiner(s): Moazzami; Nasser
• Assistant Examiner(s): SHEHNI, GHAZAL B
• Application Number:
  US11/312,672
• Publication Number:
  US 20070142943A1
• Time in Patent Office: 1,982 Days
• Field of Search: 380/40, 380/201, 380/287, 700/94
• US Class Current: 380/40
• CPC Class Codes: G11B 20/00086 Circuits for prevention of unauthorised reproduction or copying, e.g. piracy indicating unauthorised use of record carriers in general G11B23/28; scrambling for television signal recording H04N5/913; network architectures or network protocols for network security H04L63/00; cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00
• CPC Class Codes: G11B 20/00731 involving a digital rights management system for enforcing a usage restriction
• CPC Class Codes: G11B 20/00818 wherein the usage restriction limits the signal quality, e.g. by low-pass filtering of audio signals or by reducing the resolution of video signals
• CPC Class Codes: G11B 20/10037 A/D conversion, D/A conversion, sampling, slicing and digital quantisation or adjusting parameters thereof
• CPC Class Codes: G11B 20/10527 Audio or video recording; Data buffering arrangements G11B20/12 - G11B20/18 take precedence
• CPC Class Codes: G11B 2020/00057 MPEG-1 or MPEG-2 audio layer III [MP3]
• CPC Class Codes: G11B 2020/10546 specifically adapted for audio data

Abstract

A system and method for processing a digital audio signal is disclosed. The system includes an input to receive a digital audio signal and a first output to provide a first digital output signal. The digital audio signal has a first fidelity characteristic and the first digital output signal has a second fidelity characteristic. The second fidelity characteristic is determined in response to security information extracted from the digital audio signal. The first digital output signal is provided to a digital to analog converter.

Claims

1. A system, comprising:

a signal processor comprising;

an input to receive a digital audio signal, the digital audio signal having a first fidelity characteristic; and

a first output to provide a first digital output signal having a second fidelity characteristic, wherein the second fidelity characteristic is determined in response to security information extracted from the digital audio signal;

wherein the security information extracted from the digital audio signal is compared to a security profile to determine a level of security associated with the digital audio signal; and

wherein the first digital output signal is provided to a digital to analog converter.

2. The system of claim 1, wherein the digital audio signal includes a third fidelity characteristic, wherein the first digital output signal includes a fourth fidelity characteristic, and wherein the fourth fidelity characteristic is determined in response to the security information extracted from the digital audio signal.

3. The system of claim 1, further comprising:

a security module to extract the security information from the digital audio signal.

4. The system of claim 1, further comprising:

a first signal processing module to set the second fidelity characteristic.

5. The system of claim 1, wherein the first fidelity characteristic is a first sample rate and the second fidelity characteristic is a second reduced sample rate.

6. The system of claim 1, wherein the second fidelity characteristic is a sample rate that is less than or equal to about 48 kilohertz.

7. The system of claim 1, wherein the first fidelity characteristic is a first bit depth and the second fidelity characteristic is a second reduced bit depth.

8. The system of claim 1, wherein the first fidelity characteristic is a first signal to noise ratio and the second fidelity characteristic is a second reduced signal to noise ratio.

9. The system of claim 1, wherein the first fidelity characteristic is a first distortion level and the second fidelity characteristic is a second increased distortion level.

10. The system of claim 1, further comprising:

a second output to provide a second digital output signal having a third fidelity characteristic.

11. The system of claim 1, wherein the security information extracted from the digital audio signal includes digital rights management information.

12. A system comprising:

a digital to analog converter to receive a first digital signal, wherein a fidelity characteristic of the first digital signal is based on security information associated with a digital audio source of the first digital signal; and

a comparator to compare the security information to a security profile to determine a level of security associated with the first digital signal;

wherein the digital to analog converter converts the first digital signal to an analog output.

13. The system of claim 12, further comprising:

processing logic to receive a second digital signal, wherein a fidelity characteristic of the second digital signal is based on the level of security associated with the digital audio source.

14. The system of claim 12, wherein the fidelity characteristic of the first digital signal is one of a sample rate, a bit depth, a signal to noise ratio, and a distortion level.

15. A method, comprising:

receiving a digital audio input signal at a digital signal processor;

extracting, at the digital signal processor, first security information at a first time from the digital audio input signal;

comparing the extracted first security information to a security profile to determine a level of security associated with the digital audio input signal;

setting a fidelity characteristic of a digital output signal to a first level based on the level of security associated with the digital audio input signal; and

providing the digital output signal to a digital to analog converter.

16. The method of claim 15, further comprising:

extracting second security information at a second time from the digital audio input signal; and

setting a second fidelity characteristic of the digital output signal to a second level based on the extracted second security information.

17. The method of claim 15, wherein the fidelity characteristic is a sample rate.

18. The method of claim 17, wherein the sample rate is about 48 kilohertz.

19. The method of claim 15, wherein the first security information is associated with a digital rights management protocol.

20. The method of claim 15, wherein an analog output based on the digital output signal has a signal to noise ratio of less than about 96 decibels (dB).

21. A method, comprising:

receiving, at a digital signal processor, a digital audio signal, wherein a fidelity characteristic of the digital audio signal is modified based on security information extracted from the digital audio signal;

comparing the security information extracted from the digital audio signal to a security profile to determine a level of security associated with the digital audio signal; and

converting the digital audio signal to an analog output signal.

22. The method of claim 21, wherein the fidelity characteristic of the digital audio signal is one of a sample rate, a bit depth, a signal to noise ratio, and a distortion level.

23. The method of claim 21, further comprising:

providing the analog output signal to a speaker.

24. The method of claim 21, wherein the security information is associated with a digital rights management protocol.

25. A non-transitory computer readable storage medium having a computer program embedded within the non-transitory computer readable medium storage, the computer program comprising:

instructions to extract first security information at a first time from a digital audio input signal;

instructions to compare the extracted first security information to a security profile to determine a level of security associated with the digital audio input signal;

instructions to set a fidelity characteristic of a digital output signal to a first level based on the level of security associated with the digital audio input signal; and

instructions to provide the digital output signal at an output.

26. The non-transitory computer readable storage medium of claim 25, further comprising:

instructions to extract second security information at a second time from the digital audio input signal; and

instructions to set a second fidelity characteristic of the digital output signal to a second level based on the extracted second security information.