Patent Application
20220321959
The present disclosure relates to a multimedia signal processing device, and particularly to a multimedia signal processing device with a flexible authorization mechanism and a related authorization method.
High-bandwidth Digital Content Protection (HDCP) is a specification developed to protect digital entertainment content across digital interfaces, e.g. DisplayPort (DP), Digital Visual Interface (DVI), High-Definition Multimedia Interface (HDMI), Gigabit Video Interface (GVIF) and Unified Display Interface (UDI). According to the specification, the digital audio and video content will not be transmitted to a device that is not authenticated, thus protecting the content from being illegally copied as it travels across the digital interfaces. Where the connected device is not authenticated, the origination device may choose to reduce the resolution of the video and allow transmission across the non authenticated connection.
With the development of HDCP, it starts to be endorsed by the entertainment industry. In order to enable a multimedia device that plays HDCP-encrypted content, the manufacturer must obtain a license for each multimedia device. For example, the manufacture buys a batch of HDCP chips and uses the HDCP chips in its products, wherein each HDCP chip or batch of chips corresponds to unique keys (Key Selection Vector (KSV)). If one of the products is found to be non-compliant to the HDCP specifications, the corresponding keys or batch of HDCP chips may be revoked via the software revocation mechanism.
Thus, a flexible authorization mechanism for dynamically judging the valid states of the multimedia devices is desired.
An aspect of the present disclosure provides a multimedia signal processing device used between a multimedia signal source and a down-stream multimedia device. The multimedia signal processing device includes a communication unit, a multimedia decoding unit and a judging unit. The communication unit, in communication with the multimedia signal source, receives a multimedia signal from the multimedia signal source. The multimedia decoding unit decodes the multimedia signal and receives designated device information from the down-stream multimedia device. The judging unit, in communication with the communication unit and the multimedia decoding unit, performs an identification procedure according to a set of data stored in a database and the designated device information of the down-stream multimedia device to obtain a judged result to be stored in the multimedia signal processing device and have the multimedia signal processing device perform an action according to the judged result.
Another aspect of the present disclosure provides an authorization method performed by a multimedia signal processing device used between a multimedia signal source and a down-stream multimedia device. The authorization method includes steps of: storing reference device information in a database of the multimedia signal processing device; receiving designated device information from the down-stream multimedia device; and performing an identification procedure according to the reference device information stored in the database of the multimedia signal processing device and the designated device information of the down-stream multimedia device to obtain a judged result to be stored in the multimedia signal processing device and have the multimedia signal processing device perform an action according to the judged result.
According to the present disclosure, the multimedia signal processing device and the authorization method can perform a specific action such as altering the output mode or recording the device information of the suspect down-stream multimedia device for further consideration based on a comprehensive judged result. The authorization mechanism can properly judge the valid state of the down-stream multimedia device and increase the operator's confidence of the video display product.
The advantages of the present disclosure will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, in which:
The present disclosure will now be described more specifically with reference to the following embodiments. It is to be noted that the following descriptions of preferred embodiments of this invention are presented herein for purpose of illustration and description only. It is not intended to be exhaustive or to be limited to the precise form disclosed.
Please refer to
The multimedia signal processing device 10 (e.g. the set-top box) includes two input/output interface connections, i.e. a communication unit 101 and a multimedia decoding unit 102. The communication unit 101 (e.g. a tuner) receives multimedia signals broadcast from the multimedia signal source 11 and representing digital video or audio content through a broadcast medium, e.g. a cable or a wireless medium. The received multimedia signals will be decoded and outputted to the display 12. Thus, the digital video or audio content could be played on the display 12.
Before transmitting the decoded multimedia signals to the display 12, an authorization mechanism is performed to check whether the display 12 is a licensed down-stream multimedia device and allowed to play the digital video or audio content. Therefore, the multimedia signal processing device 10 further includes a judging unit 103 in communication with the communication unit 101 and the multimedia decoding unit 102. The judging unit 103 includes an identification module 1031 for performing an identification procedure. In an embodiment, middleware and/or firmware is executed in the judging unit 103 to perform the identification procedure. The identification module 1031 further includes an application programming interface (API) 1031a, a storage unit 1031b and a logic unit 1031c. The application programming interface 1031a is in communication with the communication unit 101 and the logic unit 1031c. The logic unit 1031c is further in communication with the storage unit 1031b The storage unit 1031b has a database (not shown) for storing a list of authorized/unauthorized device information indicating authorized/unauthorized down-stream multimedia devices, and this device information is called reference device information in the present disclosure. The reference device information could be provided by the multimedia signal source 11, a server or a dedicated service platform (not shown). In an embodiment, the application programming interface 1031a of the identification module 1031 receives the reference device information along with the multimedia signals from the multimedia signal source 11 through the communication unit 101.
In the identification procedure, the multimedia decoding unit 102 obtains the device information (e.g. HDCP keys) of the display 12 through data exchange. The logic unit 1031c receives the reference device information from the storage unit 1031b and the device information of the display 12 from the multimedia decoding unit 102. Then, the logic unit 1031c compares the device information of the display 12 and the reference device information in the authorized list or unauthorized list (e.g. HDCP revocation list) corresponding to the current digital video or audio content to obtain a judged result. In an embodiment, the judged result could be represented by an authorization level determined by the logic unit 1031c. The judged result is stored in the storage unit 1031b when the authorization level conforms to a specific condition. For example, if the authorization level of the display 12 indicates that the current display 12 is a suspicious display, the logic unit 1031c may adjust the output mode of the multimedia decoding unit 102 for outputting the decoded multimedia signals and/or store the related device information of the suspicious display in the storage unit 1031b. The recorded device information will be accessed by authorized personnel through an audio/video output (e.g. DP port, DVI port, HDMI port or the like) of the multimedia signal processing device 10 or reported to the multimedia signal source 11, the server or the dedicated service platform (not shown). Therefore, the multimedia signal source 11, the server or the dedicated service platform can collect more reference device information and provide the new reference device information to other multimedia signal processing devices 10 actively or upon request to update the database. This concept can be applied to build a white list or a revocation list of displays, even various types of down-stream multimedia devices in different applications.
Specifically, the output mode is a normal output mode (e.g. high-definition mode) or an altered output mode. The altered output mode involves, but is not limited to, lower resolution, lower frame-rate, black and white mode, color alteration, disabling high-dynamic-range imaging, audio out of sync, corrupted image, mute mode, no signal output or watermarking.
According to the present disclosure, the multimedia signal processing device 10 used with the multimedia signal source 11 has detection and feedback function. With the expansion of the database storing the reference device information, unauthorized down-stream multimedia device 12 can be detected in a more efficient manner. The authorization mechanism has the flexibility to allow different databases to be used by different operators and therefore affords the operator the control over the devices it allow content to flow to. This is better than revoking keys globally, and the latter usually affects the rights of the legitimate audience and obstructs pushing the digital content protection specification.
Other judged standards could be introduced to the multimedia signal processing device 10. Please refer to
The multimedia decoding unit 102 may further includes a device format acquisition unit 202b to acquire the device format information of the down-stream multimedia device 12 as a part of the device information as described in the above embodiments. For example, the device format information complies with extended display identification data (EDID). Therefore, the device format information could include resolution information, manufacturer information and/or serial number information of the down-stream multimedia device 12, but is not limited to these. The device format information is transmitted from the device format acquisition unit 202b to the identification module 1031 to participate in the identification procedure. The identification module 1031 checks whether there is doubtful format information rendering the down-stream multimedia device 12 suspicious. Therefore, the authorization level is determined with more comprehensive consideration to avoid unfair judgment.
Furthermore, the multimedia signal processing device 10 can detect a connection behavior between the multimedia signal processing device 10 and the down-stream multimedia device 12 through the multimedia decoding unit 102. For example, an old display may require several hot-plug actions in order to be successfully connected to the multimedia signal processing device 10. The multimedia signal processing device 10 may record the required hot-plug actions as the normal condition. If an inconsistent condition is detected such as that the hot-plug actions are omitted, it may be suspected that a principal component of the down-stream multimedia device 12 is replaced or modified. Such modification to the down-stream multimedia device 12 may be impermissible and should be recorded to seek further inspection. Besides, the multimedia signal processing device 10 may detect whether a connection between the multimedia signal processing device 10 and the down-stream multimedia device 12 is valid. For example, if only direct connection between the multimedia set-top box and the display is permitted, any detected intermediate device (e.g. repeater) should be tracked to determine whether to change the authorization level and adjust the output mode of the multimedia signals.
According to the present disclosure, the multimedia signal processing device 10 has a flexible authorization mechanism by considering various factors. The judgment does not rely on assigned keys only, and is adjustable to meet different conditions. Hence, the present disclosure assists in fair use of the digital video or audio content.
Please refer to
Before outputting the decoded multimedia signals to the down-stream multimedia device, the middleware and/or firmware executed in the judging unit of the multimedia signal processing device performs an identification procedure. To perform the identification procedure, the multimedia decoding unit of the multimedia signal processing device obtains the device information (e.g. HDCP keys) of the down-stream multimedia device through data exchange (step S312). Then, the logic unit of the multimedia signal processing device performs the identification procedure by comparing the device information of the down-stream multimedia device and the reference device information previously stored in the database corresponding to the current digital video or audio content to obtain a judged result (step S313). In an embodiment, the judged result could be expressed in a form of an authorization level of the down-stream multimedia device. The judged result is stored in the storage unit of the multimedia signal processing device when the authorization level conforms to a specific condition. The multimedia signal processing device will take a further action according to the judged result (step S314).
Additional authorization mechanism could be introduced in the authorization method specially adapted for different types of multimedia signals. Please refer to
In step S501, the device format acquisition unit acquires the device format information of the down-stream multimedia device. For example, the device format information complies with extended display identification data (EDID). Therefore, the device format information could include resolution information, manufacturer information and/or serial number information of the down-stream multimedia device, but is not limited to these. The device format information is transmitted from the device format acquisition unit to the identification module to participate in the identification procedure (step S313). The identification module checks whether there is doubtful format information rendering the down-stream multimedia device suspicious.
In step S502, the security module checks whether the hardware and/or software of the multimedia decoding unit and/or the down-stream multimedia device conforms to the license agreement provided by the license system (e.g. digital right management (DRM) system and/or conditional access system (CAS)) to obtain a check result. Non-compliant hardware or software will lower the authorization level. Therefore, the logic unit could determine the authorization level according to the check result about the license together with the judged result about the device information of the down-stream multimedia device.
In step S503, the multimedia signal processing device detects the connection behavior between the multimedia signal processing device and the down-stream multimedia device. If an inconsistent condition is detected, a principal component of the down-stream multimedia device may be replaced or modified. Such modification to the down-stream multimedia device may be impermissible and should be recorded to seek further inspection. Besides, the multimedia signal processing device may detect whether a connection between the multimedia signal processing device and the display down-stream multimedia device is valid. For example, if only direct connection between the multimedia signal processing device and the down-stream multimedia device is permitted, any detected intermediate device (e.g. repeater) should be tracked to determine whether to change the authorization level and adjust the output mode of the multimedia signals.
Other steps S301˜S314 could be referred to the description with reference to
According to the present disclosure, the multimedia signal processing device using the authorization method considers various factors. The authorization method is flexible to allow different databases to be used by different operators. This authorization method can protect the rights of the legitimate audience and assist in pushing the digital content protection specification.
While the disclosure has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.
