Sequence counter for an audio visual stream

1. A method for implementing a conditional access system, comprising:

transmitting, from a source device to a sink device, content comprising a sequence of content portions, each content portion having a respective sequence counter value appended thereto;

determining, in the sink device, a reference sequence counter value, which corresponds to a most recently received sequence counter value;

providing, in the sink device, an output signal representative of the content, wherein, the sink device

compares a sequence counter value associated with a particular content portion requested for playback with the reference sequence counter value, and

provides the output signal corresponding to the particular content portion in response to the comparison.

2. The method according to claim 1 , wherein the sink device stores the content with the sequence counter values in a recording device.

3. The method according to claim 1 , wherein the sink device provides the output signal if the sequence counter value associated with the particular content portion is greater than the reference sequence counter value.

4. The method according to claim 1 , wherein each of the content portions is representative of a predetermined time duration of the content.

5. The method according to claim 1 , wherein the sequence counter values are included in entitlement control messages transmitted with the content.

6. The method according to claim 1 , wherein the content further includes a device identifier associated with the source device.

7. The method according to claim 6 , wherein each of the content portions include the device identifier.

8. A method for receiving and processing content, comprising:

receiving content comprising a sequence of content portions, each content portion having a respective sequence counter value appended thereto;

determining a reference sequence counter value, which correspond to a most recently received sequence counter value;

comparing a sequence counter value associated with a particular content portion requested for playback with the reference sequence counter value; and

providing an output signal representative of the particular content portion in response to the comparison.

9. The method according to claim 8 , further comprising storing the content with the sequence counter values in a recording device.

10. The method according to claim 8 , wherein the providing step comprises providing the output signal if the sequence counter value associated with the particular content portion is greater than the reference sequence counter value.

11. The method according to claim 8 , wherein each of the content portions is representative of a predetermined time duration of the content.

12. The method according to claim 11 , wherein the sequence counter values are included in entitlement control messages transmitted with the content.

13. The method according to claim 8 , wherein the content further includes a device identifier associated with the source device.

14. The method according to claim 6 , wherein each of the content portions includes the device identifier.

15. An apparatus for receiving and processing content, comprising:

means for receiving content from a source device, the content comprising a sequence of content portions, each content portion having a respective sequence counter value appended thereto;

means for determining a reference sequence counter value, which correspond to a most recently received sequence counter value, and for comparing a sequence counter value associated with a particular content portion requested for playback with the reference sequence counter value; and

means for processing the received content to provide an output signal representative of the particular content portion, the processing means providing the output signal in response to an output of the comparing means.

16. The apparatus according to claim 15 , further comprising a recording device for storing the content with the sequence counter values.

17. The apparatus according to claim 15 , wherein the processing means provides the output signal if the sequence counter value associated with the particular content portion is greater than the reference sequence counter value.

18. The apparatus according to claim 15 , wherein each of the content portions is representative of a predetermined time duration of the content.

19. The apparatus according to claim 18 , wherein the sequence counter values are included in entitlement control messages transmitted with the content.

20. The method according to claim 15 , wherein the content further includes a device identifier associated with the source device.

21. The method according to claim 20 , wherein each of the content portions includes the device identifier.