JP2012186856A - Video transmission system and reading method for edid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a data reading method characterized by having no or short video interruption time during EDID rewriting, and a video transmission device and video reception device using the method.SOLUTION: A video transmission device transmitting a digital video signal on which content protection processing is performed to a video reception device through a digital interface: reads out information on a characteristic of the video reception device by initial setting processing executed in starting power supply from the video transmission device to the video reception device; performs initial setting of a video signal format based on the information, before CP processing; and, after that, transmits the digital video signal. When receiving a re-reading request of the information on the characteristic of the video reception device transmitted by the video reception device through a bidirectional communication line in the transmission of the video signal, the video transmission device: reads out the information on the characteristic of the video reception device through the bidirectional communication line or another bidirectional communication line differing from the bidirectional communication line; and transmits a video signal whose video signal format is reconfigured based on the read out data to the video reception device.

Description

  The present invention relates to an interface for transmitting a digital video signal including an audio signal.

Conventionally, there are digital interfaces for transmitting digital video signals, such as High Definition Multimedia Interface (HDMI), Digital Visual Interface (DVI), and DisplayPort.
These digital interfaces are used to transmit a digital video signal from the video transmission device to the video reception device. The video transmission device is, for example, a digital recorder such as a DVD (Digital Versatile Disc) playback device, an STB (Set Top Box), a personal computer or the like, and the video reception device is, for example, a television receiver or a personal computer monitor. Or the like.

JP 2006-246300 A JP 2008-252819 A

In the case of connection using a digital interface such as the above-described HDMI, a video transmitting apparatus and a video receiving apparatus that have been successfully authenticated by adopting a CP (Contents Protection, copyright protection) technology such as HDCP (High-bandwidth digital Contents Protection). Video signals can be transmitted / received only between them.
However, the conventional authentication operation is executed when the level of the HPD terminal changes from High to Low to High every time the display of the video receiving apparatus is started, the display is switched, or the data on the characteristics of the video receiving apparatus is rewritten. Therefore, there is a problem that the video transmission device does not read the data relating to the characteristics of the video reception device until the data rewriting is completed, and the video cannot be displayed or the video interruption time is long.
Patent Document 2 describes an example in which data relating to characteristics of a video receiving device is rewritten depending on the state of the video receiving device.
Japanese Patent Application Laid-Open No. 2004-151561 describes display when authentication fails, but does not describe how to eliminate or shorten video interruption time due to display switching or data rewriting related to the characteristics of the video receiving device.
In view of the above problems, an object of the present invention is to provide a data reading method, and a video transmitting apparatus and a video receiving apparatus using the same, with no or short video interruption time between display switching and data rewriting. .

  In order to achieve the above object, the present invention provides a video transmission apparatus for transmitting a digital video signal subjected to content protection processing to a video reception apparatus via a digital interface, wherein power is supplied from the video transmission apparatus to the video reception apparatus. The video transmission device reads data relating to the characteristics of the video reception device by an initial setting process that is executed at the start, and transmits the digital video signal generated based on the read data from the video reception device. When the data re-read request message is received via the bidirectional communication line incorporated in the digital interface, the data relating to the characteristics of the video receiving device is read and generated based on the read setting data. The received video signal is transmitted to the video receiver.

  According to the present invention, there is no change in the signal level of the HPD terminal even if the data relating to the characteristics of the video receiving device is rewritten, so that there is no interruption in the video or the video interruption time is short, and the data reading method and the same are used. It is possible to provide a video transmission device and a video reception device.

The block diagram which shows one Example of a structure of the video transmitter of this invention, and a video receiver. The block diagram which shows one Example of a structure of the video transmitter of this invention, and a video receiver. The block diagram which shows one Example of a structure of the video transmitter of this invention, and a video receiver. The sequence diagram which shows an example of operation | movement of the conventional EDID rewriting process and CP authentication process. The sequence diagram which shows one Example of the EDID read-out process operation | movement of this invention. The sequence diagram which shows one Example of CP process reset operation | movement of this invention. The sequence diagram which shows one Example of EDID read-out process operation | movement of this invention, and CP process reset operation | movement. The figure which compared the transmission system of the signal for every interface of one Example of this invention. The block diagram which shows one Example of a structure of the HDMI video transmitter of this invention, and a video receiver. The sequence diagram which shows one Example of the EDID read-out process operation | movement of this invention. Explanatory drawing which shows the message structure of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In each figure, components having common functions are denoted by the same reference numerals, and description thereof is omitted as much as possible to avoid duplication.

  FIG. 1 is a block diagram showing an embodiment of the configuration of a video transmission device and a video reception device according to the present invention, which is a configuration connected by HDMI. Reference numeral 100 denotes a video transmission apparatus that generates and transmits a digital video signal, and reference numeral 150 denotes a video reception apparatus. In the video transmission apparatus 100, 101 is a signal source, 102 is an encryption unit, 103 is a video / audio signal transmission unit, 104 is a CP processing unit, 105 is a CPU (Central Processing Unit), 106 is EDID (Extended Display Identification Data). A reading unit 107 is a detection unit, 108 is a power supply unit, 109 is a CEC (Consumer Electronics Control) unit, and 110 is a setting storage unit. In the video receiver 150, 151 is a display panel, 152 is an encryption / decryption unit, 153 is a video / audio signal reception unit, 154 is a CP processing unit, 155 is a CPU, 156 is an EDID storage unit, 157 is a control unit, and 159. Is the CEC section.

In FIG. 1, the video transmission device 100 is controlled by the CPU 105, and the video reception device 150 is controlled by the CPU 155. Further, the CPUs 105 and 155 are operated by a user via MMI (Man-Machine Interface) devices including a remote operation device (not shown) attached to the video transmission device 100 or the video reception device 150, respectively.
Further, the video transmission device 100 and the video reception device 150 are coupled by an HDMI cable.

In the video transmission device 100, the signal source 101 is a video signal source such as an external video input terminal, a DVD, or a broadcast receiving unit, and outputs the video signal to the encryption unit 102. The encryption unit 102 encrypts the input video signal by, for example, HDCP (content protection processing) and outputs the encrypted video signal to the video / audio signal transmission unit 103. The video / audio signal transmitting unit 103 converts the input video signal into a TMDS (Transmission Minimized Differential Signaling) serial transmission method, and receives the video / audio signal of the video reception device 150 via the TMDS signal line. The data is transmitted to the unit 153.
At this time, the CP processing unit 104 authenticates whether or not the connection partner video receiving apparatus 150 has a regular HDCP processing function via the CP processing unit 154 and a DDC (Display Data Channel) signal line, and the authentication can be performed. After that, the encryption key information is output to the encryption unit 102. In other words, the encryption unit 102 transmits the video signal obtained by subjecting the input video signal to content protection processing based on the key information input from the CP processing unit 104, so that the video reception device 150 performs the content protection. If there is no key information that can decrypt the video signal, it cannot be decrypted.
As the TMDS method, for example, a well-known technique described in JP 2007-28645 A is used.

The power supply unit 108 generates a DC voltage + 5V from an AC power supply (not shown) supplied to the video transmission device, and supplies it to the EDID storage unit 156 and the control unit 157 of the video reception device 150 via the + 5V power supply line. To do.
The EDID reading unit 106 reads out from the EDID storage unit 156 of the video signal receiving device 150 via the DDC signal line, and outputs the received EDID to the CPU 105. The CPU 105 determines the format of the video signal and audio signal to be transmitted based on the input EDID and stores the format setting information in the setting storage unit 110, while the signal source 101 causes the output format of the video signal and audio signal to be stored. Etc. Then, control is performed so that the video / audio transmission unit 103 does not transmit a video signal until the initialization and the above-described CP processing are completed.
When the detection unit 107 detects an HPD signal transmitted from the control unit 157 of the video reception device 150 via an HPD (Hot Plug Dect) signal line, the detection unit 107 outputs detection information of the HPD signal to the CPU 105.
The CEC unit 109 transmits / receives a CEC control signal such as a remote control signal and power ON / standby to / from the CEC unit 159 of the video reception device 150 via the CEC signal line.

In the video receiver 150, the video / audio receiver 153 receives the video and audio signal transmitted from the video transmitter 100, returns the video signal to the original format from the serial transmission method, and outputs it to the encryption / decryption unit 152. To do. Further, the CP processing unit 154 outputs key information obtained through authentication with the CP processing unit 104 of the video transmission device 100 to the encryption / decryption unit 152.
Using the key information obtained from the CP processing unit 154, the encryption / decryption unit 152 performs encryption / decryption processing on the video signal input from the video / audio receiving device 153, and outputs it to the display panel 151. The video is displayed.
The EDID storage unit 156 stores data indicating the characteristics of the video reception device 150, and the EDID is transmitted in accordance with the reading operation of the EDID reading unit 106 of the video transmission device 100 via the DDC signal line.
The control unit 157 transmits the HPD signal as a trigger to the detection unit 107 of the video transmission device 100 when the system is activated.
The CEC unit 159 transmits and receives CEC control signals to and from the CEC unit 109 of the video transmission apparatus 100 via the CEC signal line, and controls transmission / reception timing.

FIG. 9 is a block diagram showing an embodiment of the configuration of the video transmitting apparatus and the video receiving apparatus of the present invention. 911 is a DVD (Digital Versatile Disc), 912 is a D-VHS (Digital-Video Home System), 913 is an STB (Set Top Box), 914 is an Audio Amp, 915 is a PVR (Personal Video), and 915 is a PVR (Personal Video). 901 is an HDMI cable.
In FIG. 9, in the left and right devices respectively connected by the HDMI cable 901, the left side is a video transmission device and the right side is a video reception device. Further, for example, it is possible to combine the DVD 911 as a video transmission device and the TV 951 as a video reception device via the HDMI cable 901, Amp 914, and the HDMI cable 901.

Next, the EDID reading process according to the present invention will be described with reference to FIGS. FIG. 4 is a sequence diagram showing an example of operations of a conventional EDID reading process and CP authentication process. FIG. 5 is a sequence diagram showing an embodiment of the EDID read processing operation of the present invention, both of which are connected by the HDMI shown in FIG.
4 to 5, the video transmission device is an STB, and the video reception device is a TV. In addition, an HDMI cable is used for combining the STB and the TV, and the level change of the HPD signal in each sequence operation of the STB and the TV is shown on the right side. 4 to 7, the time elapses from the top to the bottom, and the horizontal line in the horizontal axis direction (dashed line) is the same time.
4 and 7, “H” indicates a high level (for example, 2.7 V to 5.0 V), and “L” indicates a low level (for example, 0.0 V to 0.4 V). .

In FIG. 4, supply of + 5V voltage is started from the STB to the TV via the + 5V power line at time 401, and input to the TV is started at time 402. As a result, in the TV, the HPD signal level rises from “L” to “H” between time 403 and time 404, and in the STB, it is detected that the HPD signal level becomes “H” at time 404.
When the HPD signal changes from “L” to “H”, the STB performs EDID reading and CP authentication by using a change in the level of the HPD signal as a trigger. That is, in response to the result of detecting the “H” level, the STB starts reading EDID at time 405, and the TV transmits EDID at time 406 in accordance with the STB read operation. The STB finishes reading the EDID, and then starts CP authentication for the TV at time 407. The TV starts CP authentication processing for the STB at time 408. That is, the STB reads the EDID, determines the video format to be output based on the EDID, and executes the CP authentication process.
After the CP authentication process is successful, the STB starts transmission of the video signal to the TV (time 409). At time 410, the TV ends the CP authentication processing operation and starts receiving a video signal (video / audio signal transmission start).

In this way, when the video signal is transmitted from the STB and received by the TV, and the TV decides to rewrite the EDID at time 411, the HPD signal level is switched from “H” to “L”. At time 412, the HPD signal level is set to “L”, and the TV starts writing new data to the EDID storage unit 156. When the writing is completed at time 413, the HPD signal level is switched from “L” to “H”.
When the HPD signal level is detected as “L” at time 412, the STB prohibits reading of EDID from the EDID storage unit 156, and at time 414, the HPD signal level is detected as “H”. In such a case, reading the EDID from the EDID storage unit 156 is started at time 415 using the level change as a trigger.
Thereafter, the sequence operation from time 415 to time 419 and 420 is the same as that from time 405 to time 409 and 410 described above, and thus description thereof is omitted.
In this way, when the TV decides to rewrite EDID at time 411, for example, transmission of video is interrupted between time 412 and time 419, and reception of video is performed between time 411 and time 420. Is interrupted.

  As shown in FIG. 4 described above, conventionally, when a TV decides to rewrite EDID during transmission / reception of a video signal, transmission / reception of the video signal must be interrupted. Further, since the CP authentication process is also executed, it takes a long time to interrupt the video. Therefore, as in the embodiments shown in FIGS. 5 to 7 below, the present invention is such that even if the TV decides to rewrite the EDID during transmission / reception of the video signal, the video is interrupted or the interruption time is shortened. is there.

In FIG. 5, the processing operation from turning on the power of +5 V from time 401 to time 410 until the video signal transmission / reception operation is started (video / audio signal transmission start) is the same as the conventional example of FIG. The description will be omitted, and the description will be made after the time 410.
During transmission / reception of a video signal, for example, when the TV decides to rewrite EDID at time 501, the CPU 155 (see FIG. 1) transfers the CEC unit 159 to the CEC unit 109 of the STB via the CEC signal line. A message (control command) prohibiting reading of EDID is transmitted. At this time, the HPD signal level remains in the “H” state.
At time 502, the CEC unit 109 of the STB receives the message prohibiting the reading of EDID and transmits it to the CPU 105, so that the CPU 105 prohibits the EDID reading processing operation.

When rewriting is completed at time 503, the TV transmits an EDID read request message (control command) from the CEC unit 159 to the CEC unit 109 of the STB via the CEC signal line. As a result, the CPU 105 can read the EDID. That is, the STB that has received the EDID read request message at time 504 causes the EDID read unit 106 to start reading EDID from the EDID storage unit 156 of the TV from the time 505 via the DDC signal line. At this time, the HPD signal level remains in the “H” state. Also, from time 501 to time 503 is the time for the TV to write EDID.
The STB that resets the format of the output video signal based on the read EDID starts transmission of the video / audio signal from the video / audio transmission unit 103 to the TV at time 507. Also at this time, the HPD signal level remains in the “H” state.
In this way, the video is displayed on the TV display panel 151 in a format based on the EDID rewritten between the time 501 and the time 503 after the time 508.

1 and 5, in a video signal transmission / reception system in which a video transmission device and a video reception device are combined by the HDMI method, initial setting of a video output format is performed based on EDID when power is turned on, and then CP By performing the authentication process, transmission / reception of the video signal is started. After starting transmission / reception of the video signal, when it is necessary to rewrite the EDID, a message (control command) prohibiting and requesting reading of the EDID communicated via the CEC signal line without using the level change of the HPD signal. ) Is used. Accordingly, it is possible to realize a video transmission device and a video reception device that do not interrupt video, do not require CP authentication, and can switch video and audio signals quickly even when EDID is rewritten.
In the embodiment of FIG. 5, a message for reporting the response status to the EDID read prohibition or EDID read request message is added, and the status in the video signal transmission / reception system composed of the STB and the TV is more reliably grasped. , Can also improve reliability. For example, in response to an EDID read prohibition message, when the prohibition setting message is received and EDID rewriting is started on the TV side, when the EDID read prohibition message does not reach the STB due to some malfunction, the STB An abnormal operation of starting reading can be prevented. The same applies to other embodiments of the present invention described below.
In the above-described embodiments, the HPD signal is used when initializing from Low to High only immediately after power-on (or immediately after input switching). However, in preparation for a case where the EDID reading prohibition by message or the request mechanism malfunctions, when the HPD signal becomes Low, the HPD signal may be used preferentially and the operation by the message may be stopped.

Next, CP authentication processing according to the present invention will be described with reference to FIG. FIG. 6 is a sequence diagram showing an embodiment of the CP process reset operation according to the present invention, in which signal processing is executed by the HDMI method shown in FIG.
In FIG. 6, the processing operation from the time when the DC + 5V power is turned on from time 401 to time 410 until the video signal transmission / reception operation is started is the same as in the conventional example of FIG. This will be described next.
During transmission / reception of the video signal, for example, at time 601, when the TV determines that the CP process needs to be reset, the CEC unit 159 controls the CP reset and authentication start message under the control of the TV CPU 155 (see FIG. 1). Is output to the CEC signal line. The message is received by the CEC unit 109 of the STB and transmitted to the CPU 105. At this time, the HPD signal level remains in the “H” state.
After the CEC unit 109 receives the CP reset and authentication start message at time 602, the STB CPU 105 instructs the STB CP processing unit 104 to start CP authentication with the TV. The CP processing unit 104 of the STB starts to execute CP authentication processing with the CPU processing unit 154 of the TV from time 603. The CP processing unit 104 outputs key information obtained as a result of the CP authentication process to the encryption unit 102. The video / audio signal transmission unit 103 starts transmission of the video signal encrypted by the encryption unit 102 based on the key information to the TV from the time 605 via the TMDS signal line. The video / audio signal receiving unit 153 of the TV receives the encrypted video signal and transmits it to the encryption / decryption unit 152 of the TV. The encryption / decryption unit 152 decrypts the input video signal from the time 606 based on the key information provided from the CP processing unit 154 and displays it on the display panel 151. Also at this time, the HPD signal level remains in the “H” state.

According to the embodiment of FIG. 6, in a video signal transmission / reception system in which a video transmission device and a video reception device are combined by the HDMI system, initial setting of a video output format is performed based on EDID when power is turned on, followed by CP authentication processing. By doing so, the video interface is initialized. After the transmission / reception of the video signal is started, a CP reset and an authentication start message (control command) communicated via the CEC signal line are used as a reset signal for the CP processing without using a change in the level of the HPD signal. As a result, even if the CP process is reset, the EDID read operation is not required, and the interruption of the video can be shortened. Therefore, it is possible to realize a video transmission device and a video reception device that can switch video and audio signals quickly.

Next, the case where both EDID reading processing and CP processing reset according to the present invention are performed will be described with reference to FIG. FIG. 7 is a sequence diagram showing an embodiment of an EDID read process and a CP process reset operation according to the present invention, and executes signal processing by the HDMI method shown in FIG.
In FIG. 7, the processing operation from the time when the DC + 5V power is turned on from time 401 to time 410 until the transmission / reception operation of the video signal is started is similar to the time 401 to time 410 of the conventional example in FIG. Will be omitted and will be described from the time 410.

During transmission / reception of the video signal, for example, when the TV decides to rewrite EDID and reset the CP process at time 701, the CPU 155 (see FIG. 1) transfers the CEC from the CEC unit 159 to the CEC unit 109 of the STB. A message prohibiting reading of EDID is transmitted through the signal line. The CPU 105 of the STB that has received the EDID read prohibition message at time 702 performs control so that the EDID read is not executed until the EDID read request message is received.
The TV starts rewriting EDID in the EDID storage unit 156 from time 701 and ends rewriting at time 703. When the rewriting is completed, the CPU 155 transmits an EDID read request and a CP processing reset message from the CEC unit 159 to the CPU 105 via the CEC unit 109 of the STB. At this time, the HPD signal level remains in the “H” state. Therefore, a message for prohibiting reading of EDID is used as a trigger for rewriting data.

Upon receiving the EDID read request and the CP processing reset message at time 704, the STB CPU 105 first requests the EDID storage unit 156 of the TV to read EDID at time 705. At time 706, the EDID storage unit 156 starts transmitting EDID. Next, at time 707 when the STB finishes reading the EDID, the CP processing unit 104 of the STB transmits a CP processing start message, and starts CP authentication processing with the CP processing unit 154 of the TV.
Upon reception of the CP processing start message from the STB, at time 708, the TV CP processing unit 154 performs CP authentication with the STB CP processing unit 104, and during this CP authentication processing (from time 707 to time 709). The video is interrupted. However, even at this time, the HPD signal level remains in the “H” state.

  The CP processing unit of the STB completes the CP authentication, and at time 709, the STB transmits a video signal based on the rewritten EDID and CP authentication to the video / audio signal receiving unit 103 of the TV from the video / audio signal transmitting unit 103. To start. The TV decodes and displays the video signal received based on the new CP authentication at time 710 by receiving the video signal based on the new CP authentication result and EDID transmitted from the STB. Also at this time, the HPD signal level remains in the “H” state.

  According to the embodiment of FIG. 7, in the video signal transmission / reception system in which the video transmission device and the video reception device are combined by the HDMI method, the CP authentication process is performed after the initial setting of the video output format based on EDID when the power is turned on. After executing the initialization of the video interface and starting the transmission / reception of the video signal, the trigger signal for rewriting the EDID is used for the communication via the CEC signal line without using the level change of the HPD signal. A message (control command) prohibiting reading of EDID is used. As a result, after starting transmission / reception of a video signal, it is possible to realize a video transmission device and a video reception device in which video interruption is short even when EDID rewriting and CP processing are reset.

  5 to 7 are replaced with the items shown in the comparison table of FIG. 8 described later in FIG. 2 (Example 2) and FIG. 3 (Example 3) described later. And the Display Poert method can be similarly implemented.

FIG. 10 is a sequence diagram showing an embodiment of the EDID read processing operation of the present invention. In the embodiment of FIG. 5, the CEC unit 159 of the TV transmits a message prohibiting reading of EDID only at the start of writing, transmits a read request message of EDID after writing is completed, and prohibits reading of EDID in the STB. Reading of EDID is prohibited when one message is received, and reading of EDID is prohibited until an EDID reading request message is received. However, in the embodiment of FIG. 10, during the EDID rewriting period in the EDID storage unit 156, a message prohibiting reading of EDID at a predetermined time interval (cycle), for example, 400 ms interval (time 1001, 1003, 1005) is sent to the STB. The STB may prohibit reading of the EDID every time it is received for a predetermined time longer than the predetermined period, for example, 500 ms after reception.
In this case, the TV transmits a message prohibiting reading of the EDID at a predetermined interval from the start of EDID rewriting in the EDID storage unit 156 (time 1001), and after completion (time 1007), the transmission is performed. do not do. Therefore, it is preferable to operate as if a read request message has been received 500 ms after receiving the last EDID read prohibition message.
An example of the message structure described above is shown in FIG. Each message is composed of a header 811 and an op code 812, op data 813 related to the physical address of the transmission destination, and op data 814 (or 824, 834, 844) indicating read prohibition.
(A) is an EDID read prohibition, (b) is an EDID read request, (c) is a CP reset and authentication start, (d) is a message indicating an EDID read request and CP authentication initialization, and each message is other than Physical Address Op Data is an example having one each. However, in order to suppress the frequency of messages, as shown in (e), it is slower to carry EDID read prohibition Op Data and two OP Data indicating EDID read and CP authentication initialization in one message. There is an advantage that utilization efficiency of communication lines is increased. One Op Data may be defined by combining the EDID read prohibition Op Data and the two OP Data indicating EDID read and CP authentication initialization.
At this time, the time from the EDID reading prohibition to the EDID reading is preferably set to 100 ms or more from the viewpoint of compatibility with the conventional HDMI device with HDCP. Moreover, since it will become a response delay if too long, the inside of about 500 ms is desirable.
In the present invention, since the HPD signal level can always be “H”, other than immediately after the power is turned on, the HPD terminal is always regarded as High, and another signal can be transmitted to the HPD terminal.

  FIG. 2 is a block diagram showing an embodiment of the configuration of the video transmission device and the video reception device according to the present invention, which is a configuration using a DVI interface. Reference numeral 200 denotes a video transmission device that generates and transmits a digital video signal, and reference numeral 250 denotes a video reception device. In the video transmission apparatus 200, 201 is a signal source, 202 is an encryption unit, 203 is a video signal transmission unit, 204 is a CP processing unit, 205 is a CPU, 206 is an EDID reading unit, 207 is a detection unit, 208 is a power supply unit, Reference numeral 210 denotes a setting storage unit. In the video receiver 250, 251 is a display panel, 252 is an encryption / decryption unit, 253 is a video signal reception unit, 254 is a CP processing unit, 255 is a CPU, 256 is an EDID storage unit, and 257 is a control unit.

In FIG. 2, the video transmission device 200 is controlled by the CPU 205, and the video reception device 250 is controlled by the CPU 255. Further, these CPUs 205 and 255 are operated by a user via an MMI device including a remote operation device (not shown) attached to the video transmission device 200 or the video reception device 250, respectively.
In addition, the video transmission device 200 and the video reception device 250 are coupled by a DVI cable.

In the video transmission device 200, the signal source 201 is a video signal source and outputs the video signal to the encryption unit 202. The encryption unit 202 encrypts the input video signal using, for example, HDCP, and outputs the encrypted video signal to the video signal transmission unit 203. The video signal transmission unit 203 converts the input video signal into a TMDS serial transmission method, and transmits the converted video signal to the video signal reception unit 253 of the video reception device 250 via the TMDS signal line.
At this time, the CP processing unit 204 authenticates whether the connection partner video receiving apparatus 250 has a regular HDCP processing function via the CP processing unit 254 and the DDC signal line, and after the authentication is obtained, the encryption is performed. The key information is output to the encryption unit 202. That is, the encryption unit 202 transmits the video signal obtained by subjecting the input video signal to content protection processing based on the key information input from the CP processing unit 204, and thus the video reception device 250 transmits the copy prevention signal. If there is no key information that can be decrypted, decryption is impossible.

The power supply unit 208 generates a power supply of DC voltage + 5V from an AC power supply (not shown) supplied to the video transmission device, and supplies it to the EDID storage unit 256 and the control unit 257 of the video reception device 250 via the + 5V power supply line. To do.
The EDID reading unit 206 reads out from the EDID storage unit 256 of the video signal receiving device 250 via the DDC signal line, and outputs the received EDID to the CPU 205. The CPU 205 determines the format of the video signal to be transmitted based on the input EDID and stores the format information in the setting storage unit 210, while instructing the signal source 201 about the output format of the video signal. Then, until the initialization and the above-described CP processing are completed, the video transmission unit 203 controls not to transmit the video signal.
When the detection unit 207 detects an HPD signal transmitted from the control unit of the video reception device 250 via the HPD signal line, the detection unit 207 outputs detection information of the HPD signal to the CPU 205.

In the video receiving device 250, the video receiving device 253 receives the video signal transmitted from the video transmitting device 200, returns it to the original format video signal from the serial transmission method, and outputs it to the encryption / decryption unit 252. Also, the CP processing unit 254 authenticates whether the connection partner video transmission apparatus 200 has a regular HDCP processing function via the CP processing unit 254 and the DDC signal line, and after the authentication is obtained, the CP processing unit 254 performs encryption. The key information is output to the encryption / decryption unit 252. In other words, the encryption / decryption unit 252 performs an encryption / decryption process on the input video signal based on the key information input from the CP processing unit 254 and outputs it to the display panel 251, and the video is displayed on the display panel 251. The
As described above, when an information signal capable of decrypting the content-protected video signal is input, the encryption / decryption unit 252 performs the encryption / decryption processing on the input video signal and outputs it to the display panel 251 for display. The image is displayed on the panel 251.
The EDID storage unit 256 stores data indicating the characteristics of the video reception device 250, and transmits the EDID via the DDC signal line in accordance with the read operation of the EDID reading unit 206 of the video transmission device 200.
The control unit 257 transmits the HPD signal as a trigger to the detection unit 207 of the video transmission device 200 when the system is activated.

  FIG. 3 is a block diagram showing an embodiment of the configuration of the video transmission device and the video reception device according to the present invention, which is a configuration using a display port interface. Reference numeral 300 denotes a video transmission device that generates and transmits a digital video signal, and 350 denotes a video reception device. In the video transmission apparatus 300, 301 is a signal source, 302 is an encryption unit, 303 is a video / audio signal transmission unit, 304 is a CP processing unit, 305 is a CPU, 309 is an AUX-CH (Auxiliary-Channel) unit, and 307 is A detection unit, 308 is a power supply unit, and 310 is a setting storage unit. In the video receiver 350, 351 is a display panel, 352 is an encryption / decryption unit, 353 is a video / audio signal reception unit, 354 is a CP processing unit, 355 is a CPU, 359 is an AUX-CH unit, 356 is an EDID storage unit, Reference numeral 357 denotes a control unit.

In FIG. 3, the video transmission device 300 is controlled by the CPU 305, and the video reception device 350 is controlled by the CPU 355. Further, the CPUs 305 and 355 are operated by the user via MMI devices including a remote operation device (not shown) attached to the video transmission device 300 or the video reception device 350, respectively.
In addition, the video transmission device 300 and the video reception device 350 are coupled by a DisplayPort cable.
Communication between the CP processing unit 304 of the video transmission device 300 and the CP processing unit 354 of the video reception device 350 and communication between the CPU 305 of the video transmission device 300 and the EDID storage unit 356 of the video reception device 350 are performed using an AUX-CH signal. This is performed via the AUX-CH unit 309 and the AUX-CH unit 359 connected by lines.

In the video transmission device 300, the signal source 301 is a video signal source and outputs the video signal to the encryption unit 302. The encryption unit 302 encrypts the input video signal using, for example, HDCP or DPCP (Display Port Content Protection), and outputs the encrypted video signal to the video / audio signal transmission unit 303. The video / audio signal transmission unit 303 converts the input video signal into a main link serial transmission method, and transmits the converted video signal to the video / audio signal reception unit 353 of the video reception device 350 via the main link signal line. To do.
At this time, the CP processing unit 304 performs authentication as to whether or not the connection partner video reception device 350 has a regular HDCP processing function via the CP processing unit 354 and the AUX-CH signal line, and after the authentication is obtained, The encryption key information is output to the encryption unit 302. That is, the encryption unit 302 transmits a video signal obtained by subjecting the input video signal to content protection processing based on the key information input from the CP processing unit 304, so that the video reception device 350 is subjected to the copy prevention processing. If there is no key information that can decrypt the video signal, it cannot be decrypted.

The power supply unit 308 generates a power supply of DC voltage + 3.3V from an AC power supply (not shown) supplied to the video transmission device, and supplies it to the control unit 357 of the video reception device 350 via the + 3.3V power supply line. .
The CPU 305 determines a signal format and the like based on the EDID transmitted from the EDID storage unit 356 of the video signal receiving device 350 and stores the format information in the setting storage unit 210, while outputting the video signal to the signal source 301. Specify the format. The video / audio transmission unit 303 is controlled not to transmit the video signal until the initialization and the above-described CP processing are completed.
When the detection unit 307 detects an HPD signal transmitted from the control unit of the video reception device 350 through the HPD signal line, the detection unit 307 outputs detection information of the HPD signal to the CPU 305.

In the video reception device 350, the video / audio reception device 353 receives the video signal transmitted from the video transmission device 300, returns the video signal to the original format from the serial transmission method, and outputs it to the encryption / decryption unit 352. Further, the CP processing unit 354 authenticates whether or not the connection partner video receiving apparatus 350 has a regular HDCP processing function via the CP processing unit 154 and the AUX-CH signal line. The encryption key information is output to the encryption unit 302. That is, the encryption unit 302 transmits and outputs the input video signal as a content protection processing video signal based on the key information input from the CP processing unit 304.
As described above, when an information signal capable of decrypting a video signal subjected to content protection processing is input, the encryption / decryption unit 352 performs encryption / decryption processing on the input video signal and outputs it to the display panel 351 for display. The image is displayed on the panel 351.
The EDID storage unit 356 stores data indicating the characteristics of the video reception device 350, and the EDID is stored in the video transmission device 300 via the AUX-CH unit 359, the AUX-CH signal line, and the AUX-CH unit 309. It transmits to CPU305.
The control unit 357 transmits the HPD signal as a trigger to the detection unit 307 of the video transmission device 300 when the system is activated.

With reference to FIG. 8, the types of signals in the respective interface methods of the first to third embodiments will be described together. FIG. 8 is a diagram comparing one embodiment of a signal transmission method for each interface according to the present invention.
In FIG. 8, for three types of connection interfaces (HDMI, DVI, and DisplayPort), (1) video / audio transmission method, (2) EDID read / CP authentication communication method, and (3) EDID read / CP authentication Trigger method, (4) low-speed bidirectional communication method, (5) CP method, and (6) trigger method used in the present invention instead of the conventional HPD “H” / “L” switching method during transmission / reception of video signals FIG.

  As can be seen from FIG. 8, according to the first to third embodiments, in the video signal transmission / reception system in which the video transmission device and the video reception device are combined by any one of the HDMI method, the DVI method, or the DisplayPort method, the EDID is turned on when the power is turned on. After initializing the video interface by performing the initial setting of the video output format based on the above and subsequent CP authentication processing and starting transmission / reception of the video signal, there is no interruption or short interruption of the video. A reading method, a video transmission device, and a video reception device can be realized.

100: Video transmission device 101: Signal source 102: Encryption unit 103: Video / audio signal transmission unit 104: CP processing unit 105: CPU 106: EDID reading unit 107: Detection unit 108: Power supply 109: CEC unit 110: Setting storage unit
150: Video receiver, 151: Display panel, 152: Encryption / decryption unit, 153: Video / audio signal reception unit, 154: CP processing unit, 155: CPU, 156: EDID storage unit, 157: Control unit, 159: CEC unit, 200: video transmission device, 201: signal source, 202: encryption unit, 203: video signal transmission unit, 204: CP processing unit, 205: CPU, 206: EDID reading unit, 207: detection unit, 208: Power supply unit 210: Setting storage unit 250: Video reception device 251: Display panel 252: Encryption / decryption unit 253: Video signal reception unit 254: CP processing unit 255: CPU 256: EDID storage unit 257: Control unit, 300: Video transmission device, 301: Signal source, 302: Encryption unit, 303: Video / audio signal transmission unit, 304: CP process 305: CPU, 307: detection unit, 308: power supply unit, 310: setting storage unit, 309: AUX-CH unit, 350: video receiver, 351: display panel, 352: encryption / decryption unit, 353: Video / audio signal receiving unit, 354: CP processing unit, 355: CPU,
356: EDID storage unit, 357: control unit, 359: AUX-CH unit, 901: HDMI cable, 911: DVD, 912: D-VHS, 913: STB, 914: Amp, 921: PVR, 951: TV.

In order to achieve the above object, according to an embodiment of the present invention , there is provided a video transmission system in which a transmitting device that transmits a video signal and a receiving device that receives the video signal transmitted by the transmitting device are connected by a digital interface. The digital interface includes a CEC signal line for transmitting a CEC message including Header and Op Code, the receiving device includes an EDID recording unit that records EDID indicating the performance of the receiving device, and the transmitting device includes the The EDID of the receiving device is read via the digital interface, and a video signal is transmitted to the receiving device based on the read EDID. The receiving device receives a first CEC message and a second CEC message related to the EDID of the receiving device. A CEC message is transmitted to the transmission device, and the transmission device receives the reception The EDID of the receiving device is not read until the second CEC message is received after receiving the first CEC message from the device, and the transmitting device receives the second CEC message from the receiving device. The content protection process is started upon receipt of .

Claims (8)

A video transmitting apparatus and a video receiving apparatus are connected via a digital interface that transmits a digital video signal subjected to content protection processing, and the video transmitting apparatus reads data relating to characteristics of the video receiving apparatus,
Based on the data relating to the characteristics of the video reception device read out by the initial setting process executed when power supply from the video transmission device to the video reception device is started, the digital video signal output by the video transmission device is During generation and transmission to the video receiver,
The video received from the video reception device via the bidirectional communication line provided in the digital interface to the video transmission device, the data re-read request message regarding the characteristics of the video reception device, and the read request message received. A data reading method relating to characteristics of a video receiving apparatus, characterized in that a transmission apparatus reads data relating to characteristics of the video receiving apparatus and outputs a digital video signal based on the read data.   2. The data reading method according to claim 1, wherein the initial setting process executed when the power supply is started is such that the signal level of the HPD terminal of the video reception device is changed from a low level to a high level according to the supplied power supply voltage. A data rewriting method that is executed when a change state is detected, and that when the setting data is rewritten, the video signal is transmitted based on the setting data before the rewriting. .   3. The data rewriting method according to claim 1, wherein the digital interface is one of HDMI, DVI, and DisplayPort. In a video transmission device comprising a content protection means and a video signal transmission means, outputting a digital video signal subjected to content protection processing to a digital interface and transmitting it to a video reception device,
A first bidirectional line transmission / reception means for the video transmission apparatus to read and transmit data relating to characteristics of the video reception apparatus and to / from the first bidirectional line of the digital interface for authenticating with the video reception apparatus;
A power supply for supplying power to the video receiver;
By the initial setting process executed when power supply from the power supply unit to the video receiving device is started, the data relating to the characteristics of the video receiving device is read out through the first bidirectional line transmitting / receiving means and read out. A setting storage unit for storing format setting information of video and audio signals determined based on the data;
Second bidirectional line transmission / reception means of the digital interface for receiving a data read request message or a prohibition message relating to characteristics of the video reception device from the video reception device;
After receiving the data read request message, the data relating to the characteristics of the video receiving device is read, and the setting data stored in the setting storage unit is the video and audio signal format setting information determined based on the read data And a video transmission control unit for rewriting
The video transmission control unit does not read data relating to the characteristics of the video receiving device from the video receiving device when receiving the prohibit message, and receives data relating to the characteristics of the video receiving device when receiving the request message. A video transmission device characterized by reading.   5. The video transmission apparatus according to claim 4, wherein the second bidirectional line transmission / reception means receives the content protection processing initialization request message and authenticates with the video reception device as the content protection processing initialization processing. A video transmission apparatus characterized by starting a video. In a video receiving apparatus that includes a content protection means and a video receiving means, and receives a digital video signal subjected to content protection processing, which is input from a video transmission apparatus via a digital interface,
A first bidirectional line transmission / reception that transmits / receives data related to the characteristics of the video reception apparatus to the video transmission apparatus and transmits / receives to / from the first bidirectional line of the digital interface to perform content authentication with the video transmission apparatus. Means,
A data storage unit for storing data relating to the characteristics of the video receiving device;
A second message for transmitting a prohibition message for prohibiting reading of the data and a request message for requesting reading of the data to the second bidirectional line of the digital interface while receiving a digital video signal from the video transmitting device. Sending and receiving unit,
A prohibition message for prohibiting reading of the data is transmitted to the second bidirectional line before rewriting data in the data storage unit, and a request message for requesting reading of the data is transmitted after the rewriting is completed. A video reception apparatus comprising: a video reception control unit that transmits to the bidirectional line.   7. The video receiving apparatus according to claim 6, wherein after the initialization request message for the content protection processing is transmitted from the second bidirectional line transmitting / receiving means, authentication is performed through the video receiving apparatus and the first bidirectional line transmitting / receiving means. A video receiving apparatus characterized by starting.   The video receiver according to claim 7 or 8. A video receiving apparatus comprising: encryption / decryption means for decrypting encryption applied to a digital video signal subjected to content protection processing; and display means for displaying the encrypted / decrypted video signal.

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