KR20110046806A - Apparatus and method for reducing the channel play time in portable terminal - Google Patents

Abstract

PURPOSE: An apparatus and method for reducing a channel play time in a portable terminal are provided to supply an enhanced digital broadcasting service in a portable terminal. CONSTITUTION: A broadcasting receiver(200) receives a broadcasting signal from a broadcasting station which provides a mobile broadcasting service, and a demultiplexer(210) analyzes a broadcasting stream received through the broadcasting receiver to separate the stream into the video, audio and data of a user-desirable channel. An encoding key decoding confirmation unit(220) confirms a key indicator of the audio and video received from the demultiplexer.

Description

Apparatus and method for reducing channel playback delay in a mobile device {APPARATUS AND METHOD FOR REDUCING THE CHANNEL PLAY TIME IN PORTABLE TERMINAL}

The present invention relates to an apparatus and method for digital broadcast reproduction of a portable terminal supporting a mobile broadcast service. More particularly, the present invention relates to an apparatus and a method for reducing a reproduction delay time occurring when an encrypted broadcast is reproduced in a portable terminal.

Recently, with the rapid development of portable terminals, portable terminals capable of wireless voice calls and information exchange have become necessities of life. In the early days of the spread of portable terminals, it was recognized that they could be simply carried and wirelessly talked. However, with the development of technology and the introduction of wireless Internet, the portable terminal has a growing range of applications, such as simple telephone calls or schedule management, as well as games, near field communication support, and image capturing by a digital camera. Satisfies your needs.

Furthermore, with the development of digital broadcasting technology, a portable terminal supporting a digital broadcasting reception function has been developed, and thus, the portable terminal can provide digital multimedia broadcasting to a user while moving.

Digital multimedia broadcasting can be classified into an encrypted broadcast service and an unencrypted broadcast service. The unencrypted broadcast service refers to a broadcast service that allows a general broadcast viewer to watch a broadcast freely, such as a fixed terrestrial broadcast. The encrypted broadcast service refers to a broadcast service that provides only a viewer who has obtained the right to use a broadcast service, such as a paid channel, to view the broadcast. For example, digital multimedia broadcasting may provide a broadcasting service in a form such as China Multimedia Mobile Broadcasting (CMMB) or Mobile Broadcast Management System (MBBMS) mobile broadcasting service.

When a broadcast station providing a digital broadcast service transmits a broadcast signal, the broadcast station transmits the broadcast signal configured as shown in FIG. 1 at a 1 second interval.

1 shows the structure of a typical broadcast stream frame.

As shown in FIG. 1, the broadcast stream frame 100 includes a subframe header 110, a video section 120, an audio section 130, and a data section 140. In this case, the data section 140 includes Entitlement Control Message (ECM) data including a key for decrypting the encrypted video and audio when providing the encrypted broadcast service.

When the user of the portable terminal views the encrypted broadcast service, the portable terminal receives the ECM data through the data section 140 of the channel for the user to watch. Thereafter, the portable terminal extracts an encrypted MTK (MBMS Traffic Key) from the ECM data. The portable terminal obtains a Traffic Encryption Key (TEK) required to decrypt the encrypted video and audio by decrypting the MTK using an SD Card for MBBMS. Thereafter, the portable terminal decrypts the encrypted video and audio using the obtained TEK.

However, the portable terminal receives ECM data after receiving an encrypted video and audio signal according to the structure of the broadcast signal shown in FIG.

Accordingly, a portable terminal that plays an encrypted broadcast service has a problem in that a loss of failing to decrypt the first received video and audio is not obtained because the TEK of the first received encrypted video and audio cannot be obtained.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an apparatus and method for providing an improved digital broadcast service in a portable terminal.

Another object of the present invention is to provide an apparatus and method for reducing a reproduction delay time of a digital broadcasting service in a portable terminal.

It is still another object of the present invention to provide an apparatus and method for reducing a reproduction delay time occurring when an encrypted broadcast is reproduced in a portable terminal.

It is still another object of the present invention to provide an apparatus and method for preventing loss of video and audio and reducing broadcast playback time delay by storing encrypted video and audio until the encryption key is decrypted when there is no encryption key in the portable terminal. In providing.

According to a first aspect of the present invention for achieving the above object, an apparatus for reducing a broadcast reproduction delay in a portable terminal supporting a mobile broadcast service, the broadcast receiver receiving a broadcast signal of a channel desired by the user, and the broadcast Demultiplexer (Demux) for separating video, audio and data from the broadcast signal received through the receiver, and encryption key for decrypting an encryption key for decrypting the encrypted video and audio from the data separated from the demultiplexer A decryption unit, an encryption key decryption verification unit confirming whether an encryption key capable of decrypting the video and audio separated by the demultiplexer, and an encryption key decryption determiner determine that the encryption key does not exist A buffer for storing video and audio, and the encryption key decryption unit A buffer manager which controls to transmit the video and audio signals stored in the buffer to a video / audio decoder when the encryption key capable of decoding the stored video and audio is received from the encryption key decryption confirming unit or the buffer. And a video / audio decryption unit for decoding video and audio with an encryption key decrypted by the encryption key decryption unit.

According to a second aspect of the present invention, a method for reducing broadcast reproduction delay in a mobile terminal supporting a mobile broadcast service includes, when a user receives an encrypted broadcast signal of a channel desired by a user, video, audio from the encrypted broadcast signal. And separating data, checking whether there is an encryption key capable of decrypting the separated video and audio, and if there is no encryption key capable of decoding the separated video and audio, Storing video and audio; and decrypting the stored video and audio using the decrypted encryption key when decrypting an encryption key capable of decoding the stored video and audio. .

As described above, the present invention prevents loss of video and audio by storing encrypted video and audio until decrypting an encryption key capable of decrypting encrypted video and audio when playing an encrypted broadcast in a portable terminal. And reducing the broadcast reproduction time delay.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In describing the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. The following terms are defined in consideration of the functions of the present invention, and may be changed according to the intentions or customs of the user, the operator, and the like. Therefore, the definition should be based on the contents throughout this specification.

Hereinafter, a description will be given of a technique for reducing a reproduction delay time occurring when an encrypted broadcast is reproduced in a portable terminal.

2 is a block diagram of a portable terminal for playing an encrypted broadcast channel according to the present invention. 3 illustrates a structure of a buffer of a portable terminal according to the present invention.

As shown in FIG. 2, the portable terminal supporting mobile portable broadcasting includes a broadcast receiver 200, a demultiplexer (DeMux) 210, an encryption key decryption checker 220, and a buffer manager for broadcast reproduction. 230, a buffer 240, a video / audio decryption unit 250, an encryption key decryption unit 260, an SD card 270, and a player 280. Although not shown, the portable terminal includes a memory, a CPU, a DSP, a camera, and the like that are generally known to those skilled in the art for communication and multimedia functions.

The broadcast receiver 200 receives a broadcast signal transmitted from a broadcasting station providing a mobile portable broadcasting service. In this case, the broadcast receiver 200 may be configured with various antenna structures according to the type of mobile portable broadcast service.

The demultiplexer 210 analyzes a broadcast stream received through the broadcast receiver 200 and divides the video stream into video, audio, and data portions of a channel desired by a user. In this case, the demultiplexer 210 transmits the video and audio separated from the broadcast stream to the encryption key decryption verification unit 220 and transmits the data to the encryption key decryption unit 260.

The encryption key decryption verification unit 220 confirms a key indicator of the video and audio provided from the demultiplexer 210. Thereafter, the encryption key decryption verification unit 220 confirms whether the encryption key for the checked key indicator is decrypted and usable by the encryption key decryption unit 260. For example, in the case of a China Multimedia Mobile Broadcasting (CMMB) service or a Mobile Broadcast Management System (MBBMS) mobile broadcasting service, the encryption key decryption confirming unit 220 may be connected to a video provided from the demultiplexer 210. Check the Audio Key Indicator. Thereafter, the encryption key decryption verification unit 220 confirms that the traffic encryption key (TEK) for the checked key indicator is decrypted and usable by the encryption key decryption unit 280.

The buffer 240 selectively stores the video and audio information provided from the demultiplexer 210 according to whether the encryption key for the video and audio information checked by the encryption key decryption verification unit 220 is available. . For example, when the encryption key decryption checker 220 confirms that the encryption key for the video and audio information is not available, the buffer 240 stores the video and audio information provided from the demultiplexer 210. Save it.

When the buffer 240 stores video and audio information, as illustrated in FIG. 3, the buffer 240 stores a storage space 300 for storing video and audio information and a key indicator for distinguishing the video and audio information. It consists of a storage space 310 for storing.

The buffer manager 230 controls to store video and audio information together with the key indicator in the buffer 240 in cooperation with the encryption key decryption verification unit 220.

In addition, the buffer manager 230 controls the video / audio decoder 250 to transmit video and audio information prepared with an encryption key among the video and audio information stored in the buffer 240. In this case, the buffer management unit 230 and the encryption key decryption confirming unit 220 may be implemented in various hardware or software structures, such as a central processing unit (CPU).

The encryption key decryption unit 260 decrypts the encryption key from the data information provided from the demultiplexer 210. For example, in the case of a CMMB service or an MBBMS mobile broadcast service, the encryption key decryption unit 260 may include Entitlement Control Message (ECM) data included in the data section 140 of the broadcast signal configured as shown in FIG. 1. Extracts an encrypted MTK (MBMS Traffic Key), which is the first key needed. Thereafter, the encryption key decryption unit 260 decrypts the MTK using the user information of the SD card 270 to obtain a traffic encryption key (TEK) necessary to decrypt the encrypted video and audio.

The SD card 270 includes user information capable of decrypting an encrypted MBMS Traffic Key (MTK). At this time, the SD card 270 is provided with the user information to decrypt the MTK from the operator when the user subscribes to the MBBMS service.

The video / audio decryption unit 250 decrypts the encrypted video and audio information using the encryption key provided from the encryption key decryption unit 260. In this case, the video / audio decryption unit 250 decrypts the encrypted video and audio information using an encryption key mapped to a key indicator of encrypted video and audio information.

The video / audio decryption unit 250 decrypts the encrypted video and audio information provided from the encryption key decryption confirming unit 220 or the buffer 240. That is, when the encryption key decryption verification unit 220 confirms that the encryption key is usable, the video / audio decryption unit 250 encrypts the encryption using the encryption key provided from the encryption key decryption unit 260. The encrypted video and audio information provided from the key decryption verification unit 220 is decrypted. Meanwhile, when the encryption key decryption unit 260 acquires encrypted video and audio information stored in the buffer 240, the video / audio decryption unit 250 is obtained by the encryption key decryption unit 260. The encrypted video and audio information provided from the buffer 240 is decrypted using one encryption key.

The playback unit 280 plays the video and audio information decrypted by the video / audio decryption unit 250 and decrypted and displayed on the display unit. That is, the playback unit 280 plays the unencrypted video and audio information provided from the video / audio decryption unit 250 so that the user can watch the broadcast.

The playback unit 280 may include a playback buffer (not shown) for temporarily storing video and audio information for playback. The playback unit 280 starts playback of the video and audio information when more than a reference amount of video and audio information is accumulated in the playback buffer. In this case, the playback unit 280 may provide a natural screen playback to the user without interruption during broadcast playback.

If the video and audio signals are lost when an encryption key is received later than the video and audio signals when the playback buffer is used, the playback unit 280 delays the time when data is accumulated in the playback buffer according to the lost video and audio signals. This happens. However, when the portable terminal receives an encryption key later than the video and audio signals, the portable terminal temporarily stores the video and audio signals in the buffer 240 so that video and audio information is not lost. Can be reduced.

Hereinafter, a description will be given of a method for reducing a reproduction delay time that occurs when playing an encrypted broadcast in a portable terminal.

4 illustrates a procedure of decrypting an encrypted broadcast channel in a portable terminal according to the present invention. In the following description, it is assumed that the portable terminal provides a CMMB service or an MBBMS mobile broadcast service.

Referring to FIG. 4, when the portable terminal provides an encrypted broadcast service, the portable terminal receives an encrypted broadcast signal using the broadcast receiver 200 in step 400. For example, the portable terminal receives a broadcast signal configured as shown in FIG.

When the encrypted broadcast signal is received, the portable terminal proceeds to step 410 to separate video information, audio information and data information from the received broadcast signal. That is, the portable terminal uses the demultiplexer 210 to separate video information, audio information, and data information from a broadcast signal. At this time,

In step 420, the portable terminal determines whether an encryption key for the encrypted video and audio information separated in step 410 exists. For example, the encryption key decryption verification unit 220 of the portable terminal checks a key indicator of the video and audio provided from the demultiplexer 210. Thereafter, the encryption key decryption verification unit 220 confirms whether the encryption key for the checked key indicator is decrypted and usable by the encryption key decryption unit 260.

In addition, after separating the video information, the audio information and the data information from the broadcast signal, the portable terminal proceeds to step 430 to decrypt the encryption key for decrypting the encrypted video and audio information from the data information. For example, in the case of a CMMB service or an MBBMS mobile broadcast service, the encryption key decryption unit 260 of the portable terminal extracts an encrypted MTK from ECM data included in data information. Thereafter, the encryption key decryption unit 260 decrypts the MTK using the user information of the SD card 270 to obtain a TEK necessary for decrypting the encrypted video and audio.

If the encryption key for the encrypted video and audio information does not exist in step 420, the portable terminal proceeds to step 440 and stores the encrypted video and audio information for which the encryption key does not exist in the buffer 240. . For example, when a broadcast signal is configured as shown in FIG. 1, when the portable terminal first receives a broadcast signal of a corresponding channel by executing a portable broadcast program or changing a channel for the first time, the broadcast signal may have a structure of the broadcast signal. There may be no encryption key for the video and audio information. In this case, the portable terminal stores the encrypted video and audio information in the buffer 240.

Thereafter, the portable terminal proceeds to step 420 and checks whether an encryption key for the encrypted video and audio information stored in step 440 exists.

If there is an encryption key for the encrypted video and audio information in step 420, the portable terminal proceeds to step 450 to decrypt the encrypted video and audio information using the encryption key. For example, in the case of a CMMB service or an MBBMS mobile broadcast service, the encryption key corresponds to a TEK. The TEK is usually transmitted in a period of 10 seconds to 1 minute. Accordingly, the portable terminal can decode the video and audio received in the TEK period range through the TEK provided from the broadcasting station. Here, the TEK period may be set in a period of approximately 10 seconds to 1 minute according to the setting of the transmission server or the policy of the operator. For another example, the portable terminal may decode video and audio information of a second received broadcast signal by using a TEK extracted from data information of the first received broadcast signal.

When the portable terminal extracts the encryption key for the video and audio information stored in the buffer 240 in step 430, the portable terminal proceeds to step 450 and stored in the buffer 240 using the extracted encryption key. Decode video and audio information. For example, when the broadcast signal is configured as shown in FIG. 1, the portable terminal receives video and audio information before data information. Accordingly, the portable terminal may store the minimum received video and audio information in the buffer 240 in step 440. Then, when the portable terminal extracts the encryption key through the data information received later than the video and audio information, the portable terminal proceeds to step 450 to decode the video and audio information stored in the buffer 240.

After decrypting the encrypted video and audio information in step 450, the portable terminal proceeds to step 460 and reproduces the video and audio information decrypted in step 450 for the user to confirm.

Looking at the process of receiving the broadcast signal and decrypting the encrypted video and audio information as described above in detail,

First broadcast stream frame video received: 0 seconds

First broadcast stream frame audio received: 0.08 seconds

First broadcast stream frame data received: 0.1 second

First broadcast stream frame encryption key decryption: 0.2 seconds

(After 1 second)

Second broadcast stream frame video received: 1 second

Receive second broadcast stream frame audio: 1.08 seconds

Receive second broadcast stream frame data: 1.1 seconds

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In the above-described embodiment, when the portable terminal does not have the encryption key of the video and audio of the first broadcast stream frame and the video and audio information is lost, the portable terminal may receive the video and audio of the second broadcast stream frame. It takes 1.08 seconds. That is, the portable terminal has a playback delay of 1.08 seconds for playing the broadcast.

Accordingly, in step 420 of FIG. 4, the portable terminal checks whether the encrypted video and audio received from the broadcasting station have an encryption key for decrypting and stores the received encrypted video and audio in a buffer in step 440. do. In step 430, the portable terminal is capable of decrypting the encrypted video and audio stored in the buffer when the encryption key decryption having a key indicator corresponding to the video and audio stored in the buffer is completed. It is possible to reduce broadcast playback delay time.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications may be made without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by the equivalents of the claims.

1 is a diagram showing the structure of a conventional broadcast stream frame;

2 is a diagram showing the configuration of a portable terminal for playing an encrypted broadcast channel according to the present invention;

3 is a view showing the structure of a buffer of a portable terminal according to the present invention; and

4 is a diagram illustrating a procedure for decrypting an encrypted broadcast channel in a portable terminal according to the present invention.

Claims (20)

An apparatus for reducing broadcast reproduction delay in a mobile terminal supporting a mobile broadcast service, A broadcast receiver receiving a broadcast signal of a channel desired by a user; A demux for separating video, audio, and data from the broadcast signal received through the broadcast receiver; An encryption key decryption unit that decrypts an encryption key capable of decoding the encrypted video and audio from the data separated by the demultiplexer; An encryption key decryption verification unit for confirming whether an encryption key capable of decoding the video and audio separated by the demultiplexer exists; A buffer for storing video and audio determined that the encryption key does not exist in the encryption key decryption checker; A buffer manager which controls to transmit the video and audio signals stored in the buffer to the video / audio decoder when the encryption key decoder decodes an encryption key capable of decoding the video and audio stored in the buffer; And a video / audio decoder configured to decode the video and audio provided from the encryption key decryption confirming unit or the buffer with an encryption key decrypted by the encryption key decryption unit. The method of claim 1, The buffer stores video and audio and a key indicator corresponding to the video and audio determined that the encryption key does not exist in the encryption key decryption checker. Device. The method of claim 1, And the encryption key decryption unit decodes a traffic encryption key (TEK) required to decrypt the encrypted video and audio from the data separated by the demultiplexer. The method of claim 1, The encryption key decoder extracts an MBMS Traffic Key (MTK) from the data provided from the demultiplexer, decrypts the MTK by using user information, and decodes the encryption key. Device. The method of claim 4, wherein And the encryption key decryption unit decrypts the MTK by decrypting the MTK using user information obtained from an SD card including user information. The method of claim 1, The encryption key decryption confirming unit checks a key indicator of the video and audio separated by the demultiplexer, and confirms whether the encryption key corresponding to the key indicator checked by the encryption key decryption unit has been decrypted. A device for reducing broadcast reproduction delay. The method of claim 1, The encryption key decryption confirming unit, if there is an encryption key for decoding the video and audio separated by the demultiplexer, transmits the video and audio to the video / audio decoding unit, characterized in that the broadcast reproduction delay Device for reducing. The method of claim 1, The video / audio decryption unit, when decoding the encrypted video and audio, broadcast reproduction, characterized in that to obtain an encryption key corresponding to the key indicator (Key Indicator) of the encrypted video and audio from the encryption key decryption unit Device for reducing delay. The method of claim 1, The mobile broadcast service is a device for reducing broadcast playback delay, characterized in that the mobile broadcast management system (MBBMS). The method of claim 1, And a playback unit for playing the video and audio decoded by the video / audio decoding unit. A method for reducing broadcast reproduction delay in a mobile terminal supporting a mobile broadcast service, When the user receives an encrypted broadcast signal of a desired channel, separating video, audio, and data from the encrypted broadcast signal; Checking whether there is an encryption key capable of decoding the separated video and audio; If there is no encryption key for decoding the separated video and audio, storing the video and audio; And decrypting the stored video and audio using the decoded encryption key when the encryption key capable of decoding the stored video and audio is decoded. The method of claim 11, The storing process, And storing the video and audio and a key indicator corresponding to the video and audio determined that there is no encryption key capable of decoding the separated video and audio. How to reduce latency. The method of claim 11, And after decoding the video, audio, and data, decrypting an encryption key for decrypting the video and audio from the data. The method of claim 13, Decrypting the encryption key, Extracting MTK (MBMS Traffic Key) from the data separated from the encrypted broadcast signal; And decrypting the MTK by using the user information to decode the Traffic Encryption Key (TEK). 15. The method of claim 14, The process of decoding the TEK, And decoding the MTK by using the user information acquired from an SD card including user information to decode the MTK. The method of claim 11, The process of checking the existence of the encryption key, Checking a key indicator of the separated video and audio; And determining whether an encryption key corresponding to the key indicator has been decoded. The method of claim 11, And if there is an encryption key capable of decoding the separated video and audio, decoding the separated video and audio using the encryption key. The method of claim 11, Decoding the video and audio, Identifying an encryption key corresponding to a key indicator of the encrypted video and audio, And decoding the encrypted video and audio using the identified encryption key. The method of claim 11, The mobile broadcast service is a method for reducing broadcast playback delay, characterized in that the mobile broadcast management system (MBBMS). The method of claim 11, And after the decoding of the video and audio, reproducing the decoded video and audio.

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