Circuit and Method for Link Verification by HDCP Receiver

• US 20200134236A1
• Filed: 12/27/2019
• Published: 04/30/2020
• Est. Priority Date: 12/27/2019
• Status: Active Grant

• Current Assignee: Altera Corporation (Intel Corporation)
• Original Assignee: Intel Corporation
• Inventors: Oh, Boon Hong, Low, Yeong Liang, Ahmed Saad Ahmed Ahmed, Laila
• Granted Patent: US 12,075,114 B2
• Time in Patent Office: Days
• CPC Class Codes: G06F 21/44 Program or device authentication
• CPC Class Codes: G06F 21/606 by securing the transmission between two devices or processes
• CPC Class Codes: G06F 21/84 output devices, e.g. displays or monitors
• CPC Class Codes: H04N 21/23 Processing of content or additional data; Elementary server operations; Server middleware
• CPC Class Codes: H04N 21/43635 HDMI
• CPC Class Codes: H04N 21/4367 Establishing a secure communication between the client and a peripheral device or smart card
• CPC Class Codes: H04N 21/44008 involving operations for analysing video streams, e.g. detecting features or characteristics in the video stream arrangements characterised by components specially adapted for monitoring, identification or recognition of video in broadcast systems H04H60/59
• CPC Class Codes: H04N 5/05 Synchronising circuits with arrangements for extending range of synchronisation, e.g. by using switching between several time constants

Abstract

A method for an audiovisual receiver to request an audiovisual transmitter to reset a communication link includes requesting the reset when the audiovisual receiver determines that the communication link is unlocked. The communication is determined to be unlocked when the active geometry of successive audiovisual frames transmitted from the transmitter to the receiver is determined by the receiver to be inconsistent. The communication is also determined to be unlocked when the interval between control bits of the successive audiovisual frames is inconsistent. When one or both of the inconsistencies is determined, the receiver sets an error bit in a register of the receiver that is accessible by the transmitter to determine from the receiver that the communication link is unlocked.

Claims

1. A method comprising:

receiving audiovisual frames by a data input port of an audiovisual receiver transmitted from an audiovisual transmitter;

transition-minimized differential signaling (TMDS) decoding the audiovisual frames by a TMDS circuit of the audiovisual receiver;

determining, by an active picture measure circuit of the audiovisual receiver, subsequent to TMDS decoding, if the active picture geometry of the successive ones the audiovisual frames is unchanged or changed; and

signaling to the audiovisual transmitter by a data output port of the audiovisual receiver to reverify a validity of the audiovisual receiver and to restart transmission of the audiovisual frames from the audiovisual transmitter to the audiovisual receiver if the active picture geometry of the successive ones the audiovisual frames is changed.

2. The method of claim 1, further comprising signaling to the audiovisual transmitter by the data output port of the audiovisual receiver to continue transmitting audiovisual frames to the audiovisual receiver if the active picture geometry of the successive ones the audiovisual frames is unchanged.

3. The method of claim 2, wherein determining, by the active picture measure circuit subsequent to TMDS decoding, if the active picture geometry of the successive ones the audiovisual frames is unchanged or changed comprises:

counting active video lines of successes ones of the audiovisual frames by an active picture measure circuit of the audiovisual receiver subsequent to TMDS decoding;

counting pixels of the active video lines of the successes ones of the audiovisual frames by the active picture measure circuit subsequent to TMDS decoding; and

determining by the active picture measure circuit if a number of the active video lines of the one of the successive frames are equal or unequal and if a number of pixels of the active video lines of the ones of the successive frames are equal or unequal.

4. The method of claim 3, wherein signaling to the audiovisual transmitter by the audiovisual receiver to reverify a validity of the audiovisual receiver and to restart transmission of the audiovisual frames from the audiovisual transmitter to the audiovisual receiver if the numbers of the active video lines of successes ones of the audiovisual frames are changed and the numbers of the pixels of the active video lines of the successes ones of the audiovisual frames are changed.

5. The method of claim 4, wherein signaling to the audiovisual transmitter by the data output port of the audiovisual receiver to continue transmitting audiovisual frames to the audiovisual receiver if the active picture geometry of the successive ones the audiovisual frames is unchanged comprises signaling to the audiovisual transmitter by the audiovisual receiver to continue transmitting audiovisual frames to the audiovisual receiver if numbers of the active video lines of successes ones of the audiovisual frames are unchanged and numbers of the pixels of the active video lines of the successes ones of the audiovisual frames are unchanged.

6. The method of claim 5, wherein signaling to the audiovisual transmitter by the data output port of the audiovisual receiver to reverify the audiovisual receiver to restart transmission of the audiovisual frames from the audiovisual transmitter to the audiovisual receiver comprises storing an error code for a public key for one of the audiovisual frames in a buffer readable by the audiovisual transmitter.

7. The method of claim 6, wherein signaling to the audiovisual transmitter to by the data output port of the audiovisual receiver to continue transmitting audiovisual frames to the audiovisual receiver if the active picture geometry of the successive ones the audiovisual frames is unchanged comprises storing the public key for one of the audiovisual frames in a buffer readable by the audiovisual transmitter.

8. The method of claim 7, further comprising receiving the successes one of the audiovisual frames from the TMDS circuit by the active picture measure circuit.

9. The method of claim 1, further comprising determining, by a high-bandwidth digital content protection (HDCP) control (CTL) detector and measure circuit of the audiovisual receiver, subsequent to TMDS decoding, if intervals between control (CTL) bits of the successive ones the audiovisual frames is unchanged or changed;

and

signaling to the audiovisual transmitter by the data output port of the audiovisual receiver to reverify a validity of the audiovisual receiver and to restart transmission of the audiovisual frames from the audiovisual transmitter to the audiovisual receiver if the intervals between the CTL bits of the successive ones the audiovisual frames is changed.

10. The method of claim 9, further comprising signaling to the audiovisual transmitter by the data output port of the audiovisual receiver to continue transmitting audiovisual frames to the audiovisual receiver if the intervals between the CTL bits of the successive ones the audiovisual frames is unchanged.

11. The method of claim 10, wherein signaling to the audiovisual transmitter by the data output port of the audiovisual receiver to reverify the audiovisual receiver to restart transmission of the audiovisual frames from the audiovisual transmitter to the audiovisual receiver comprises storing an error code for a public key for one of the audiovisual frames in a buffer readable by the audiovisual transmitter.

12. The method of claim 11, wherein signaling to the audiovisual transmitter to by the data output port of the audiovisual receiver to continue transmitting audiovisual frames to the audiovisual receiver if the active picture geometry of the successive ones the audiovisual frames is unchanged comprises storing the public key for one of the audiovisual frames in a buffer readable by the audiovisual transmitter.

13. The method of claim 12, further comprising receiving the successes one of the audiovisual frames from the TMDS circuit by the HDCP CTL detector and measure circuit.

14. A method comprising:

receiving audiovisual frames by a data input port of an audiovisual receiver transmitted from an audiovisual transmitter;

transition-minimized differential signaling (TMDS) decoding the audiovisual frames by a TMDS circuit of the audiovisual receiver;

determining, by a high-bandwidth digital content protection (HDCP) control (CTL) detector and measure circuit of the audiovisual receiver, subsequent to TMDS decoding, if intervals between control (CTL) bits of the successive ones the audiovisual frames is unchanged or changed; and

signaling to the audiovisual transmitter by the data output port of the audiovisual receiver to reverify a validity of the audiovisual receiver and to restart transmission of the audiovisual frames from the audiovisual transmitter to the audiovisual receiver if the intervals between the CTL bits of the successive ones the audiovisual frames is changed.

15. The method of claim 14, further comprising signaling to the audiovisual transmitter by the data output port of the audiovisual receiver to continue transmitting audiovisual frames to the audiovisual receiver if the intervals between the CTL bits of the successive ones the audiovisual frames is unchanged.

16. The method of claim 15, wherein signaling to the audiovisual transmitter by the data output port of the audiovisual receiver to reverify the audiovisual receiver to restart transmission of the audiovisual frames from the audiovisual transmitter to the audiovisual receiver comprises storing an error code for a public key for one of the audiovisual frames in a buffer readable by the audiovisual transmitter, and wherein signaling to the audiovisual transmitter to by the data output port of the audiovisual receiver to continue transmitting audiovisual frames to the audiovisual receiver if the active picture geometry of the successive ones the audiovisual frames is unchanged comprises storing the public key for one of the audiovisual frames in a buffer readable by the audiovisual transmitter.

17. The method of claim 14, further comprising determining, by an active picture measure circuit of the audiovisual receiver, subsequent to TMDS decoding, if the active picture geometry of the successive ones the audiovisual frames is unchanged or changed;

signaling to the audiovisual transmitter by a data output port of the audiovisual receiver to reverify a validity of the audiovisual receiver and to restart transmission of the audiovisual frames from the audiovisual transmitter to the audiovisual receiver if the active picture geometry of the successive ones the audiovisual frames is changed; and

signaling to the audiovisual transmitter by the data output port of the audiovisual receiver to continue transmitting audiovisual frames to the audiovisual receiver if the active picture geometry of the successive ones the audiovisual frames is unchanged.

18. The method of claim 17, wherein determining, by the link verification circuit subsequent to TMDS decoding, if the active picture geometry of the successive ones the audiovisual frames is unchanged or changed comprises:

counting active video lines of successes ones of the audiovisual frames by an active picture measure circuit of the audiovisual receiver subsequent to TMDS decoding;

counting pixels of the active video lines of the successes ones of the audiovisual frames by the active picture measure circuit subsequent to TMDS decoding; and

determining by the active picture measure circuit if a number of the active video lines of the one of the successive frames are equal or unequal and if a number of pixels of the active video lines of the ones of the successive frames are equal or unequal, wherein signaling to the audiovisual transmitter by the audiovisual receiver to reverify a validity of the audiovisual receiver and to restart transmission of the audiovisual frames from the audiovisual transmitter to the audiovisual receiver if the numbers of the active video lines of successes ones of the audiovisual frames are changed and the numbers of the pixels of the active video lines of the successes ones of the audiovisual frames are changed,

wherein signaling to the audiovisual transmitter by the data output port of the audiovisual receiver to continue transmiting audiovisual frames to the audiovisual receiver if the active picture geometry of the successive ones the audiovisual frames is unchanged comprises signaling to the audiovisual transmitter by the audiovisual receiver to continue transmiting audiovisual frames to the audiovisual receiver if numbers of the active video lines of successes ones of the audiovisual frames are unchanged and numbers of the pixels of the active video lines of the successes ones of the audiovisual frames are unchanged,

wherein signaling to the audiovisual transmitter by the data output port of the audiovisual receiver to reverify the audiovisual receiver to restart transmission of the audiovisual frames from the audiovisual transmitter to the audiovisual receiver comprises storing an error code for a public key for one of the audiovisual frames in a buffer readable by the audiovisual transmitter, and

wherein signaling to the audiovisual transmitter to by the data output port of the audiovisual receiver to continue transmiting audiovisual frames to the audiovisual receiver if the active picture geometry of the successive ones the audiovisual frames is unchanged comprises storing the public key for one of the audiovisual frames in a buffer readable by the audiovisual transmitter.

19. A circuit comprising:

a data input port of an audiovisual receive to receive audiovisual frames from an audiovisual transmitter;

transition-minimized differential signaling (TMDS) decoder of the audiovisual receiver coupled to the data input port to TMDS decode the audiovisual frames using a TMDS circuit of the audiovisual receiver;

an active picture measure circuit of the audiovisual receiver coupled to the TMDS decoder to determine subsequent to TMDS decoding, if the active picture geometry of the successive ones the audiovisual frames is unchanged or changed; and

a link verification circuit of the audiovisual receiver coupled to the active picture measure circuit to signal by a data output port of the audiovisual receiver to the audiovisual transmitter to reverify a validity of the audiovisual receiver and to restart transmission of the audiovisual frames from the audiovisual transmitter to the audiovisual receiver if the active picture geometry of the successive ones the audiovisual frames is changed.

20. The circuit of claim 19, further comprising a high-bandwidth digital content protection (HDCP) control (CTL) detector of the receiver coupled to the TMDS decoder circuit to determine, subsequent to TMDS decoding, if intervals between control (CTL) bits of the successive ones the audiovisual frames is unchanged or changed, wherein the link verification circuit is to the signal to the audiovisual transmitter by the data output port of the audiovisual receiver to reverify a validity of the audiovisual receiver and to restart transmission of the audiovisual frames from the audiovisual transmitter to the audiovisual receiver if the intervals between the successive the CTL bits of successive one the audiovisual frames is changed.