JP2012157020A - Video transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a video transmission device which can precisely discriminate that a prescribed video signal source and a prescribed video display device are connected to input/output respectively.SOLUTION: The video transmission device includes: a first register which is set by receiving a CEC message which the video signal source issues by reading EDID of the video transmission device and is reset by a rise of 5V supplied from a video signal device; and a second register which is set by reading the EDID of the video display device and discriminating that the device is the prescribed video display device and is reset when a state that HPD is "L" continues for a prescribed period or above. Only when the first and second registers are both set, the prescribed video signal source, the video transmission device and the video display device are determined to be directly connected.

Description

  The present invention relates to a video signal transmission device that receives a video signal output from a video signal source, processes the video signal, and outputs the processed video signal to a display device.

  An example of a video signal transmission device that wirelessly transmits a video signal of a video signal source to a display device after video compression is described in Patent Document 1.

  There is HDMI (High-Definition multimedia Interface) described in Non-Patent Document 2 as a digital video interface between devices. In this HDMI, CEC (Consumer Electronics Control) is determined as a communication specification between devices using a line in an HDMI cable. In the CEC specification, Patent Document 2 describes an example in which control between devices is performed using a control information of connected devices and a CEC message that conveys device information.

  In HDMI, Non-Patent Document 1 describes that a video signal source reads EDID (Extended Display Identification Data) information indicating the display capability and specifications of a video display device, and selects a video format to be output. As a timing at which the signal source reads this EDID information, an HPD (Hot Plug Detect) signal indicating that the cable is connected is indicated by a logic level “H”, and after the change from the logic level “L” to “H”. Is described in Non-Patent Document 2. By using these mechanisms, the specification of the video display device can be transmitted to the video signal transmission device, and the specification of the video signal transmission device can be transmitted to the video signal source.

Japanese Patent Laid-Open No. 2004-165921 JP 2007-214952 A

A DTV Profile for Uncompressed High Speed Digital Interfaces CEA-861B, Consumer Electronics Association, USA, May 2002 High-Definition Multimedia Interface Specification, Informational Version 1.0, HDMI, LLC, USA, 2003/9/4

  When a video signal is wirelessly transmitted, the transmission speed is often inferior to that of a wired connection. Therefore, as described in Patent Document 1, the video signal is transmitted with a reduced transmission amount. In order to increase the video compression rate while maintaining high image quality, it is necessary to perform advanced video processing before video compression, and to perform video processing to compensate for the image quality peculiar to video compression even when decoding on the receiving side. .

  The video processing before video compression is performed by the video processing unit of the video signal source, and the video processing after decoding is performed by the video processing unit of the display device. Can be applied. In order for this method to function, a predetermined video signal source, a video transmission device, and a video signal display device must be connected.

  As shown in Non-Patent Document 1, HDMI has a mechanism for directly transmitting the specifications of the video display device to the video transmission device using the EDID mechanism. On the other hand, it is conceivable to use the physical address included in the CEC message in order to convey the specifications of the video signal source to the video transmission apparatus.

  However, there is a case where it is not desired to mount the CEC message because the CEC message is transmitted wirelessly because there is a problem described in Patent Document 1 and a special device is required. Furthermore, in order to quickly know the change of equipment and perform optimal control, it is necessary not only to obtain the equipment specifications by reading the EDID at the timing of HPD and arrival of the CEC message, but also to detect when the connection state is lost. However, the specific mechanism was not shown.

  The object of the present invention is to solve the above-mentioned problems and to quickly and reliably detect that a predetermined video signal source and a predetermined display device are directly connected to the input and output of the video transmission device, respectively. An object of the present invention is to provide a video transmission apparatus capable of performing the above.

The present invention is a first register that is set in response to a CEC message issued by the video signal source reading and issuing the EDID of the video transmission device, and is reset at the rising edge of 5V supplied from the video signal source;
A second register that is set by reading the EDID of the video display device, determining that the video display device is a predetermined video display device, and resetting when the HPD is in the “L” state for a predetermined period or longer;
Only when both the first and second registers are set, it is determined that a predetermined video signal source, a video transmission device, and a video display device are directly connected.
Further, when the first register is a register that is initialized when the power is turned off, if the state continues for a predetermined time after the state of the first register changes, the first register state is stored in the non-volatile memory, and the video The second feature is that when the power of the transmission apparatus is turned off and the first register is initialized and the power is turned on again, the state of the nonvolatile memory is returned to the first register.

  When the video transmission device is wireless, the video signal source converts video processing that is easily compressed into a high-quality video signal, the video transmission device suppresses high-compression video processing, and the video display device suppresses image quality degradation unique to high-compression video. Since video processing can be performed, high image quality can be realized within a limited transmission speed range. If either the video signal source or the video display device is not a predetermined device, there may be a negative effect if the above-mentioned image quality is improved, so standard video that does not require special video processing before and after. It has the feature of applying compression processing.

  Also, a video in which a specific CEC message is transmitted only when a predetermined video signal source and a video display device are connected to the wireless transmission side and the wireless reception side, and transmission of the specific CEC message is stopped for other devices. By acting as a transmission device, it is possible to prevent the CEC general device from being affected by the bus neck caused by the specific CEC message transmission.

  The video transmission apparatus to which the present invention is applied can detect at a precise timing that a predetermined video signal source and a predetermined video display apparatus are directly connected to the input / output terminals, respectively. It is possible to provide a video transmission system with special features and a special control signal transmission function.

1 is a block diagram of a video system comprising a video transmission device, a video signal source, and a video display device according to first and second embodiments of the present invention. The figure which showed the control sequence in 1st Example of this invention State transition diagram of video transmission apparatus in first embodiment of the present invention State transition diagram of video transmission apparatus in second embodiment of the present invention Block diagram of a video system comprising a video transmission device, a video signal source, and a video display device according to a third embodiment of the present invention.

  A video transmission apparatus according to the present invention will be described below with reference to the drawings. In the following embodiments, the same components are denoted by the same reference numerals.

  FIG. 1 is a block diagram showing a configuration of a video display system 1 according to the present invention. In FIG. 1, the video transmission device 15 includes a wireless transmission unit 12 and a wireless reception unit, and transmits a video signal output from the video signal source 11 to the video display device 14.

  First, the flow of the video signal will be described. The video signal source 11 performs predetermined scaling processing and image quality improvement signal processing in the video signal processing unit 115 on the video signal generated by the video / audio signal forming unit, and then performs TMDS reception of the wireless transmission unit 12 from the TMDS transmission unit 114. The signal is transmitted to the unit 124 via the line 103. The output of the TMDS reception unit 124 is encoded by the video compression unit 126 and the amount of video data is compressed, and then transmitted from the wireless transmission unit 127 to the wireless reception unit 136 of the wireless reception unit 13 by the radio wave 104.

  The output of the wireless reception unit 136 is decoded into an uncompressed video signal format by the video decoding unit 137, and after suppression of noise and the like due to video compression by the video processing circuit 135, the video display device It is transmitted to the 14 TMDS receivers 144 via the line 107. The output of the TMDS receiving unit 144 is input to the video processing unit 145, subjected to signal processing in accordance with the characteristics of the display unit 147, and then applied to the display unit 147 and displayed.

  The EDID reading units 113 and 133 read data of the EDID storage units 123 and 143 storing data indicating the specifications of the wireless transmission unit 12 and the video display device 14 via the lines 102 and 106, respectively. . With this mechanism, it is understood that the video signal source 11 and the wireless reception unit 13 are directly connected to a predetermined wireless transmission unit 12 and a video display device 14, respectively. After that, the video signal source 11 and the wireless reception unit 13 respectively send predetermined video signals to the wireless transmission unit 12 and the video display device 14 using the CEC message exchange functions 111, 121, 131, and 141 through the lines 101 and 105, respectively. It is informed that the source 11 and the wireless receiving unit are connected, and recognizes a special system connection configuration in which the predetermined video signal source 11, the video transmission device 15, and the video display device 14 are directly connected. When this recognition is established, the video processing unit 115 of the video signal source 11 takes charge of pre-processing for increasing the video compression efficiency, and the video processing unit 145 of the video display device 14 is specific to video compression, such as mosquito noise. It can suppress and provide comprehensive high image quality.

  2 shows the video signal source 11, the wireless transmission unit 12, the wireless reception unit 13. It is the figure which showed the control sequence between the video display apparatuses. FIG. 3 is a diagram showing the state transition of the wireless transmission unit 12 (abbreviated as Tx in FIG. 3) on the left side and the state transition of the wireless reception unit 13 (abbreviated as Rx in FIG. 3) on the right side.

  1 will be described below using the state sequence diagram of FIG. 2 and the state transition diagram of FIG. 3 together.

  After the power is turned on, the wireless transmission unit 12 acquires the connection state before the power is turned off from the nonvolatile memory 129 and copies it to the first register 128 (311 in FIG. 3). Thereafter, it waits for the video signal source 11 to start supplying + 5V power of DDC (312 in FIG. 3). Upon receiving the start of + 5V supply from the DDC, the first register 128 is reset, and at the same time, “H” is added to the HPD to permit reading of the EDID storage unit 123 (211 and 212 in FIG. 2, 313 in FIG. 3). When the EDID reading unit 113 of the video signal source 11 reads the data from the EDID storage unit 123 (213 in FIG. 2) and determines that the wireless transmission unit has a function of forming a predetermined configuration from a predetermined manufacturer name, product model number, etc. The CEC message is transmitted to the wireless transmission unit 12 (214 in FIG. 2, 314 in FIG. 3), and the data in the register 128 is set (315 in FIG. 3).

  The wireless reception unit 13 resets the second register 138 immediately after power-on (321 in FIG. 3), and supplies DDC + 5V to the video display device 14 (221 in FIG. 2, 322 in FIG. 3). Upon detecting a change to HPD = “H” indicated by the video display device 14, the EDID reading unit 133 reads the EDID storage unit 143 data of the video display device 14 (223 in FIG. 2, 323 in FIG. 3), and a predetermined If it is determined that the image display device is used, the second register 138 is set (324 in FIG. 3).

  The second register 138 is reset when HPD = “L”, such as when the connection between the wireless reception unit 13 and the video display device 14 is disconnected or the specification of the video display device changes (321 in FIG. 3). ). Thereafter, steps 321 to 324 in FIG. 3 are repeated. At this time, when the period of HPD = “L” is as short as about 2 seconds, for example, the set state is maintained without resetting the second register, and the set / reset operation is performed based on the EDID reading result, and the short state change May be avoided.

  When both the first register 128 and the second register 138 are set, the wireless transmission unit 12 and the wireless reception unit 13 communicate with each other (215 in FIG. 2). It is possible to determine whether the system has a special system configuration based on common recognition.

  If the video signal source is not turned on when the video transmission apparatus is turned on, DDC + 5V is not supplied, and the connection state remains unknown. In order to avoid this, a nonvolatile memory is used to store the state of the register 128 immediately before the power is turned off.

In general, since it is known that the number of rewrites increases in the nonvolatile memory, as a contrivance to reduce the number of rewrites, the first register 128 is nonvolatile for a predetermined time (for example, 30 seconds) or more. Reliability can be improved by starting writing only when it is different from memory state storage.
In the above operation, when it is determined that the predetermined video signal source, the video transmission device, and the video display device are directly connected, the video transmission device 15 increases the compression rate of the video compression unit 126 and also uses the CEC message to display the video. The video processing 115 of the signal source 11 is pre-processed so that the video compression rate is easily increased. The image processing 145 of the image display device 14 is advantageously subjected to filter processing for reducing noise peculiar to image compression, thereby enabling high-quality image transmission.

  When it is determined that a predetermined video signal source, a video transmission device, and a video display device are directly connected, the device status such as cooperation between high-quality video processing, menu display, power ON / OFF, etc. among the three parties The exchange of special CEC messages necessary for the cooperation of each other can also be permitted. If this special CEC message is issued when the direct connection is not confirmed, it may become a CEC bus neck and affect other CEC message control. By confirming the above direct connection, there is an effect of preventing this influence.

  Further, since problems such as timing delay are likely to occur during wireless transmission of CEC messages, it is possible to intentionally stop CEC message transmission and use the CEC transmission function only during the direct connection.

  In the video transmission apparatus shown in the video system block diagram of FIG. 1, an embodiment using the state transition diagram of FIG. 4 instead of the state transition diagram of FIG. 3 is shown.

When the video signal source, the video transmission device, and the video display device are not in a predetermined direct connection state, the purpose is to reduce unnecessary CEC message transmission when stopping the CEC message. The same operation parts as those in the state transition diagram of FIG. The additional portion will be described below with reference to FIG.
If it is decided to supply DDC + 5V whenever a predetermined video signal source 11 issues a CEC message, in the state 312, if the wireless transmission unit 12 receives a message before DDC + 5V is supplied, It can be determined that the video signal source is not connected. Therefore, even if the first and second registers are set and CEC message transmission is permitted, the CEC communication unit 121 does not respond and resets the first register 128 (411 in FIG. 4). Then, the DDC + 5V standby state 312 is continued.

  In the state 312, when the first and second registers are set and CEC message transmission is permitted, when the CEC message is sent to the CEC communication unit 131 of the wireless reception unit 13, it is wirelessly transmitted to the wireless transmission unit. 12 is transferred from the CEC communication unit 121 to the CEC communication unit 111 of the video signal source 11 (state 412 in FIG. 4). This transfer operation is repeated a predetermined number of times (twice in FIG. 4) so as to be surely transmitted. In order not to issue an extra CEC command, even if the CEC communication unit 111 cannot receive, it may be set not to automatically retransmit.

  The wireless receiving unit 13 also adds a function of resetting the predetermined EDID that could not be read in the state 324 of FIG.

  As described above, the video transmission apparatus that transfers the CEC command only in the case of the combination of the predetermined video signal source, the video transmission apparatus, and the video table display apparatus suppresses a case where an extra CEC message is erroneously transmitted. Can do.

  A system block diagram according to the third embodiment of the present invention is shown in FIG. The same components as those in FIG. 1 are given the same numbers, and 16 is a video transmission device with an audio processing function. An audio processing 167, a speaker 168, and the like are connected to the video transmission apparatus. A direct connection between a predetermined video signal source, a video transmission device, and a video display device is detected, and a linked operation between the direct connection devices is realized based on a predetermined operation procedure.

  As an example of these linking operations, it is conceivable to detect a powerful scene by video processing, and perform cooperative control of audio processing according to the scene. In addition, when the video signal source has stereoscopic video content, the video transmission device with audio processing function can reproduce stereoscopic audio, and the video display device can display stereoscopic video, the stereoscopic audio playback / video display is used. There is also.

  A video transmission device having a wireless video transmission function, etc. has a high-quality and high-efficiency video transmission function when a predetermined video signal source and a video display device are combined, and a standard video transmission function other than the predetermined combination. There is an advantage that it can be switched accurately.

  Further, there is an advantage that a special control signal transmission function can be provided only when a predetermined video signal source and a video display device are combined.

  The video transmission device according to the present invention can accurately determine a combination of a predetermined video signal source and a video display device to realize high-quality wireless video transmission, a special control signal transmission function, and video signal processing. .

DESCRIPTION OF SYMBOLS 1 ... Video display system 11 ... Video signal source 12 ... Wireless transmission unit 13 ... Wireless reception unit 14 ... Video display device 15 ... Video transmission device 16 ... Video transmission device 111, 121, 131, 141, 161 with audio processing function CEC Communication unit 112, 122, 132, 142, 162 ... control unit 113, 133, 165 ... EDID reading unit 123, 143, 163 ... EDID storage unit 114, 134, 166 ... TMDS transmission unit 124, 144, 164 ... TMDS reception unit 116: Video / audio signal generation units 115, 135, 145 ... Video signal processing unit 126 ... Video compression unit 127 ... Wireless transmission unit 136 ... Wireless reception unit 137 ... Video decoding units 128, 138, 171, 172 ... Registers 129, 169 ... Nonvolatile memory unit 147 ... Display unit 167 ... Audio processing 168 ... Speaker

  In order to solve the above-described problems, an embodiment of the present invention uses, for example, the technical idea described in the claims.

Claims (5)

A first register that is set in response to a CEC message transmitted by the video signal source and is reset at a rising edge of a predetermined voltage supplied from the video signal source;
A second register is provided that is set by reading the EDID of the video display device to determine that the video display device is a predetermined video display device, and is reset when the HPD is in the “L” state for a predetermined period or longer. In video transmission equipment,
A video transmission apparatus, wherein when the first and second registers are set, it is determined that the video signal source, the video transmission apparatus, and the video display apparatus are connected. The video transmission device includes a video compression unit that compresses a video signal,
When it is determined that the video signal source, the video transmission device, and the video display device are connected, the compression rate in the video compression unit is increased and the video signal processing circuit included in the video signal source is 2. The video transmission according to claim 1, wherein information transmission is performed so as to enter a mode in which a video processing circuit included in the video display device is used as a post-processing of the video signal. apparatus.   When it is determined that the video signal source, the video transmission device, and the video display device are connected, transmission of a specific CEC message is started. When the determination is not made, the specific CEC message is transmitted. 2. The video transmission apparatus according to claim 1, wherein message transmission is not performed.   2. The transmission operation and the reception operation for pulling down a CEC line are started when it is determined that the video signal source, the video transmission device, and the video display device are connected. Video transmission device.   When the state lasts for a predetermined time after the state change of the first register, the first register state is stored in the nonvolatile memory, the power of the video transmission device is turned off, and the first register is initialized. 2. The video transmission apparatus according to claim 1, wherein when the power is turned on again, the state of the nonvolatile memory is copied to the first register.

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