KR20080058993A - Device and method for displaying video data in digital broadcasting receiver - Google Patents

Abstract

A display device of a digital broadcasting receiver and a method thereof are provided to play broadcasting data received from a changed service channel or a set service channel, thereby reducing a channel change time or broadcasting screen display time. A screen display method of a digital broadcasting receiver comprises the following steps of: setting information about a changed broadcasting channel if a broadcasting channel is changed(411,413); analyzing video data received through the changed broadcasting channel, displaying video data as a still screen if specific frame video data is received, and buffering received broadcasting data(415,417); checking whether time stamp information of the buffered broadcasting data is received; and If so, it is displayed video and audio synchronized by controlling a time offset of the audio/video(419).

Description

DEVICE AND METHOD FOR DISPLAYING VIDEO DATA IN DIGITAL BROADCASTING RECEIVER}

1 is a diagram showing the structure of a digital broadcast receiver for changing a service channel according to an embodiment of the present invention.

Fig. 2 is a diagram showing the configuration of the broadcast receiver 110 of the DVB-H digital broadcast receiver.

3 is a diagram showing the configuration of a protocol processing unit 120 of the DVB-H digital broadcast receiver.

4A to 4F are diagrams illustrating an IP-based service channel data structure received by the DVB-H digital broadcast receiver.

5A through 5C are diagrams for describing a procedure of processing data of service channels into a screen according to an embodiment of the present invention.

6 is a flowchart illustrating a procedure of reproducing broadcast data upon channel change according to an embodiment of the present invention.

7 is a flowchart illustrating a procedure of identifying and displaying an I frame in FIG. 6.

FIG. 8 is a flowchart illustrating a procedure of buffering and playing back broadcast data received after displaying a still picture in FIG.

9 is a diagram illustrating a configuration of a mobile terminal having a digital broadcast receiver according to an embodiment of the present invention.

The present invention relates to an apparatus and method for displaying broadcast data of a digital broadcast receiver, and more particularly, to an apparatus and method for displaying broadcast data during channel switching.

Currently, the digital broadcast receiver receives and displays various digital broadcast signals. The digital broadcast signal is a digitally encoded and modulated signal, and the receiver must demodulate and decode the data in reverse. Therefore, the digital broadcast receiver should have a tuner, a broadcast data demodulator, a broadcast data decoder, and the like. Currently, the digital broadcasting method can be roughly divided into DMB (Digital Multimedia Broadcasting) and DVB (Digital Video Broadcasting). The digital broadcasting uses a method of serving a plurality of service channels in one frequency channel, and the service channels are channels for transmitting program information and / or broadcast information of channels for transmitting digital broadcast signals broadcast from broadcasting stations. It may consist of.

In addition, current portable terminals have a tendency to mount a multimedia dedicated processor or to enhance a multimedia function, and among such multimedia functions, a digital broadcast receiver has been installed. The wireless terminal may be a mobile phone, a notebook computer, a personal digital assistant, a portable multimedia player (PMP), or the like. The portable terminal may include an RF communication unit that performs a wireless communication function.

When the digital broadcast receiver switches a channel to another broadcast while viewing a broadcast reception function and a broadcast reception function, the digital broadcast receiver cannot watch the broadcast during the channel switching time. That is, the digital broadcast receiver cannot receive the broadcast signal during the channel switching time, and thus the screen cannot be displayed on the display unit. Conventionally, the screen display is stopped by displaying a screen or specific images for guiding channel switching during the channel switching time as described above.

Accordingly, an object of the present invention is to provide an apparatus and method for displaying a first broadcast picture received in a switch service channel as a still picture when switching channels in a digital broadcast receiver.

Another object of the present invention is to provide an apparatus and method for displaying broadcast data in a set time unit when broadcast data having a size set before synchronization is buffered when switching channels in a digital broadcast receiver.

Another object of the present invention is to display the first broadcast screen as a still picture before the synchronization when switching channels in the digital broadcast receiver, and to display the broadcast data in a set unit of time if the broadcast data of the set size is buffered, the synchronous control signal The present invention provides an apparatus and method for displaying broadcast data in synchronization with audio and video upon reception.

DETAILED DESCRIPTION A detailed description of preferred embodiments of the present invention will now be described with reference to the accompanying drawings. It should be noted that the same components in the figures represent the same numerals wherever possible.

In the following description, specific details such as DVB-H digital broadcasting, time of burst channel, etc. are shown to provide a more general understanding of the present invention. It will be apparent to those skilled in the art that the present invention may be readily practiced without these specific details and by modifications thereof.

Embodiments of the present invention relate to a digital broadcast receiver or a portable terminal having such a digital broadcast receiver for quickly displaying data of a switched broadcast channel or a set broadcast channel when switching channels or attempting to watch a broadcast. The digital broadcasting may be classified into a digital multimedia broadcasting (DMB) method, a digital video broadcasting (DVB) method, a media flow (forward link only), or the like. The DMB, DVB, and media flow methods all use digital broadcasting. In addition, the DVB scheme includes a DVB_T scheme and a DVB_H scheme, and the DVB_H scheme uses time slicing and IP-based broadcast signals. The digital broadcast receiver according to the embodiment of the present invention will be described by way of example as receiving and processing the broadcast signal of the DVB_H. However, the digital broadcast receiver according to the embodiment of the present invention can be applied to both the DVB method, the DMB method, and the media flow method.

 Hereinafter, terms used in the embodiments of the present invention are defined as follows. First, a "channel" means a frequency channel selected by the tuner, and a "service" is a channel (broadcast channel) of an actual broadcasting station transmitted on the selected channel. Means a service channel to be distinguished, "event" (event) refers to the programs provided by each service. In an embodiment of the present invention, the channel is used as a "physical channel" and the service is used as a "service channel" in order to prevent confusion caused by the use of the terms. In digital broadcasting, a plurality of service channels are transmitted in one physical channel, a physical channel means a channel frequency set in a tuner, and a service channel means broadcasting stations in the physical channel. The service channel may be distinguished by the PID in the case of DMB and DVB-T, and in the case of DVB-H, by a combination of PID, IP address, and / or port information (these are referred to as service channel information). Can be distinguished. Here, the specific frame video data is frame video data for decoding and may be frame video data encoded alone without reference to other frame data or frame video data encoded with reference to video data of another frame once. In this case, it is assumed that the specific frame is an I frame broadcast signal.

1 is a diagram illustrating a structure of a digital broadcast receiver for changing a service channel according to an embodiment of the present invention.

Referring to FIG. 1, the controller 100 controls the overall operation of the digital broadcast receiver. The key input unit 170 generates key data according to a user's selection and applies the generated key data to the controller 100. Here, the user's command generated through the key input unit 170 may be a reproduction and recording of a digital broadcasting channel, a change of service channels, and the like. According to an embodiment of the present invention, when a service channel change command is generated in a state of starting a broadcast play mode and performing a play mode, the user can quickly display broadcast data of a service channel to be set or changed. Accordingly, the controller 100 controls the display of broadcast data when switching channels.

The memory 160 may include a program memory for storing a program for controlling the operation of the digital broadcast receiver, and a data memory for storing data generated during program execution. The program memory of the memory 160 includes a program for quickly displaying broadcast data of a switching service channel and a setting service channel when switching a service channel and requesting to start a play mode according to an embodiment of the present invention.

The broadcast receiver 110 receives data of service channels selected by a user under the control of the controller 100. The protocol processor 120 processes the protocol of the data of the service channels and separately outputs video data, audio data, and broadcast information data. In the DVB-H scheme, the protocol processor 120 processes the protocols of the IP datagram to extract and output audio data, video data, and broadcast information data. In the DMB or DVB-H scheme, the protocol processor 120 demultiplexes audio and video data by analyzing a transport stream (TS).

The decoder 130 may include a data decoder for decoding audio, video, and broadcast information. The audio decoder decodes and outputs encoded audio data of a service channel. The video decoder decodes and outputs video data of service channels, respectively. The data decoder decodes the broadcast information data as described above. In the embodiment of the present invention, it is assumed that the decoder 130 includes the audio and video decoder, and the data decoder processes the software in the controller 100.

An embodiment of the present invention provides an apparatus and method for rapidly displaying broadcast data of a changed service channel when changing a service channel being watched in a play mode.

In general, when a channel is changed, a digital broadcast receiver requires a few seconds (that is, a channel changeover time) to receive and stably reproduce broadcast data of a changed service channel. This is because the digital broadcast receiver receives the broadcast data of the selected service channel, buffers it to a predetermined size, and decodes the same. Therefore, the screen indicating that the channel is changed or the specific image is displayed during the service channel change time. In addition, the digital broadcast data is composed of audio, video and broadcast information as described above, and the audio and video data are synchronized with each other. Therefore, when reproducing the broadcast data, the digital broadcast receiver must reproduce the audio and video data in synchronization. Therefore, the channel change time becomes longer.

According to an embodiment of the present invention, when a service channel change is requested, specific frame video data of the changed service channel is checked, and when the specific frame video data is confirmed, video data of the checked frame is displayed on the display unit 150, and the received broadcast is received. Buffer the data. Accordingly, when the channel is changed, the broadcast data of the changed service channel can be displayed quickly. The time for playing the video data of the specific frame is maintained until the buffered broadcast data becomes a set size. When the buffered data reaches a set buffer size, the controller 100 plays the buffered audio and video data. At this time, reproduction of the audio and video data may be in a state in which control information (time stamp) for synchronizing the display time of the audio and video data is not received. The playback is maintained until time stamps for synchronizing the playback times of audio and video are received, and the playback time of the audio and video data is received at the time point at which the sync time control information is received. Output in synchronization.

The video data of the specific frame may be I frame video data. The buffering data may be set to a size that can be reproduced for about 1 to 3 seconds. The control information (time stamp) for synchronizing the reproduction time of the audio and video data is output to control the decoding time stamp (DTS) for synchronizing the decoding start time of the decoder and the output time of the decoded broadcast data. The control information may be a presentation time stamp (PTS). In this case, the time stamp may use one of a DTS and a PTS, and synchronization of the audio and video data may be implemented using an audio DTS and a video DTS (or an audio PTS and a video PTS).

First, in the embodiment of the present invention, when the service channel is changed, the controller 100 checks the broadcast data of the changed service channel output from the protocol processor 120. If the broadcast data received is the first specific frame video data received in the changed service channel, the controller 100 controls the video decoder of the decoder 130 to decode the video data of the specific frame, and the display unit 150 decodes the decoded video data. Control to display the recorded video data. In this case, the encoded video data frame of the service channel may include an I frame (Infra frame), a P frame (Previous or Predicted frame), and a B frame (Bidirectional frame). Here, the I frame is a key frame and means a video data frame including all video data compressed and coded directly from a source in the same manner as JPEG. The P frame means a video data frame configured based on information of a previous key frame (here, the I frame). The B frame refers to a video data frame configured based on information of an I or P frame before and after. In this case, the I frame can be decoded by the video frame itself when decoding. Therefore, in the embodiment of the present invention, the specific frame may be an I frame. At this time, the played screen may be a still image.

Secondly, in the embodiment of the present invention, the controller 100 buffers the broadcast data received in the changed service channel into the input buffer of the decoder 130 while displaying the video data of the I frame. When the buffered broadcast data is buffered to a set size, the controller 100 controls the audio decoder and the video decoder of the decoder 130 to decode the buffered audio and video data, respectively, and the speaker 155 and the display unit 150 respectively. Control to reproduce the decoded audio and video data. The buffer size may be set to a size that allows the digital broadcast receiver to reproduce broadcast data of 1 to 3 seconds. For example, DVB using PAL reproduces 25 frames of video data per second, and NTSC using DMB reproduces about 30 frames of video data per second. Accordingly, in the DVB scheme, the buffered video data may be 25 to 75 frames of video data. In this case, the played screen may be a video screen. In addition, video and audio reproduced through the display unit 150 and the speaker 155 may be in a state in which they are not synchronized with each other.

Third, in the embodiment of the present invention, when the time stamps of the audio and video are received while the synchronization is not performed, the control unit 100 synchronizes by applying the offsets of the audio and video time stamps. After that, the audio and video are decoded and reproduced normally in the synchronized state.

As described above, in the embodiment of the present invention, the screen is displayed in two or three steps when the service channel is changed. That is, the second display procedure may be omitted in the channel change display process. In this case, when the service channel is changed, the first I frame data received from the changed service channel is checked and played. Thereafter, synchronization is performed according to the time stamp offset of the video and audio, and then audio and video of the changed channel are normally played back. In the embodiment of the present invention described below, the DVB-H digital broadcast receiver will be described as an example. However, the same applies to other types of digital broadcast receivers including DMB.

In the following description of the embodiment of the present invention, it is assumed that the digital broadcast receiver uses the DVB-H method.

FIG. 2 is a diagram showing the configuration of the broadcast receiver 110 of the DVB-H digital broadcast receiver. FIG. 3 is a diagram showing the configuration of the protocol processing unit 120 of the DVB-H digital broadcast receiver. 4F illustrates an IP-based service channel data structure received by the DVB-H digital broadcast receiver. FIGS. 5A through 5C show broadcast data of a service channel in a DVB-H digital broadcast receiver. It is a figure for explaining the process of selecting and processing.

First, referring to the DVB_H data mapping configuration of FIGS. 4A to 4F, the DVB_H data has an MPEG2-TS structure. In FIG. 4A, each TS packet has a size of 188 bytes, and may be configured with a packet header of 4 baht and a payload of 184 bytes. Here, the packet header has packet sync and PID information. The PID may be used as information for identifying service channels and information for identifying a payload. FIG. 4B is a configuration of an MPE section that can be carried in the payload of FIG. 4A, wherein the MPE section includes a table identifier (table_ID), information for error correction of the received data (MPE-FEC), and time slicing of received data. It may be composed of information for. 4C shows an example of using IP V6 as the configuration of the IP datagram. The IP datagram includes an IP version (such as IP V6 or IP V4), source IP information, destination IP information, and the like. 4D is UDP and includes port information (Scr Prt, Dst Prt) of the calling and called party. 4E is a configuration of FLUTE / ARC and includes an Electronic Service Guide (ESG), files, and the like. 4F is an RTP configuration, in which audio and video data are included.

Secondly, referring to the time slicing and decoding procedures of video data of FIGS. 5A to 5C, as described above, in DVB-H, a plurality of service channels are transmitted on one physical channel, and each service channel is illustrated in FIG. 5A. As shown, time alignment, multiplexing, and transmission are performed. FIG. 5A assumes that 10 service channels ch1 to ch10 are transmitted to one physical channel, and ch3 is selected as a service channel. The period of ch1-ch10 is referred to as ?? t, is burst on the ch3 service channel, and the remaining service channel bursts are off time. Accordingly, the DVB-H supplies power so that the broadcast receiver 110 can operate only in the selected service channel using a time slicing technique as shown in FIG. 5B. The burst data of ch3 received as shown in FIG. 5B is decoded in the ?? t section as shown in FIG. 5C.

Referring to FIG. 2, the broadcast receiver 110 of each physical channel includes a tuner 200 and a broadcast data demodulator, and the broadcast data demodulator 210 includes an analog to digital converter 210, a demodulator 220, a PID filter 230, and demodulation. Controller 240 and the like. The tuner 200 is set to a physical channel frequency at which a service channel selected by a user is transmitted, and receives signals of service channels of the set physical channel. The tuner 200 is a PLL for generating a frequency for setting a physical channel, a mixer for outputting a broadcast signal of a physical channel set by mixing a received broadcast signal and a physical channel frequency generated in the PLL, and a set physical channel frequency band. And a bandpass filter for filtering and outputting a signal.

The demodulation controller 240 controls the tuner 200 according to the channel control data output to the control unit 100 to set the physical channel frequency of the selected service channel, and sets the PID of the selected service channels in the PID filter 230. At this time, the controller 100 analyzes the PSI / SI information output from the broadcast receiver 110 and the SDP information included in the ESG (Electronin Service Guide) output from the protocol processor 120 to analyze PID, IP, and port information of service channels selected by the user. Check it. That is, if the PID filtered by the PID filter 230 is a network information table (NIT), a service description table (SDT), or an event information table (EIT), the controller 100 may use a physical channel and a service channel from the table (PSI / SI). You can check their PIDs. In addition, the control unit 100 extracts and analyzes an SDP from ESG data having the structure as shown in FIG. 4E in the protocol processing unit 120, and PID, IP, and port information for identifying audio and video data of each service channel and each service channel. You can check them. Accordingly, the controller 100 analyzes the PSI / SI and / or SDP data to determine PID, IP, and port information for distinguishing each service channel and audio and video data of each service channel. When the user selects the service channels, the controller 100 outputs channel data for filtering the PID of the physical channel and the service channel that transmits the selected service channel data to the demodulation controller 240. In this case, when the user selects the service channels, the controller 100 outputs channel control data including the PID of the service channel to the demodulation controller 240.

The demodulation controller 240 then sets the physical channel frequency for receiving the selected service channel in the tuner 200 and sets the PID of the selected service channel in the PID filter 230. Then, the tuner 200 receives a broadcast signal of the set physical channel frequency from the received broadcast signal. The A / D converter 210 receiving the output of the tuner 200 converts the output signal of the tuner 200 into digital data, and the demodulator 220 demodulates the modulated broadcast signal into original data. The demodulator 220 may be configured as an OFDM or COFDM demodulator. In this case, the data demodulated by the demodulator 220 may be a TS packet stream of MPEG2-TS as shown in FIG. 4A, and the TS packet includes PID information which is an identifier for identifying a service channel. The PID filter 230 filters service channel data having a PID of the service channel from the demodulated IP datagram, and transmits PSI / SI information to the controller 100. In addition, the data as shown in FIG. 4B output from the PID filter 230 may include MPE-FEC (MultiProtocol Encapsulation-Forward Error Correction) and time slicing information. Then, the demodulator controller 240 times-slicing the received burst data if the data includes the information as shown in FIG. 4B. That is, the demodulation controller 240 controls the power supply of the tuner 110 and the demodulator 220 using the time slicing information of FIG. 4B. In this case, the time slicing information includes burst on time information of the service channel, and the demodulation controller 240 uses the tuner 200 and the demodulator 220 in the burst data section of the service channel selected using the time slicing information. Power is supplied to the power supply, and the power supply is stopped in other sections. In addition, the demodulation controller 240 performs the MPE-FEC function on the data of the selected service channel output from the PID filter 230 using the MPE section information as shown in FIG. 4B.

As described above, the demodulation controller 240 controls the tuner 200 according to the channel control data output to the controller 100 to set the physical channel frequency of the selected service channel, and sets the PID of the service channels in the PID filter 230. Do this. And MPE-FEC function to control the operation of time slicing (time slicing) to reduce the power consumption of the digital broadcast receiver by the MPE section information as shown in FIG. Do this. In this case, the data output from the demodulation controller 240 may be an IP datagram having a structure as shown in FIG. 4C.

Accordingly, in the configuration of the broadcast receiver 100, the tuner 200 selects broadcast signals of a set physical channel, and the demodulator 220 converts the output of the tuner 200 into digital data and demodulates (OFDM or COFDM). In this case, the demodulated data has an MPEG2 TS structure as shown in FIG. 4A and includes PID information for distinguishing service channels of the corresponding physical channel. The PID filter 230 analyzes the PID of the demodulated data and filters demodulated data having the PSI / SI PID and the PID of the selected service channel. In this case, data having a PID of information related to the PID list such as the PSI / SI is transmitted to the controller 100, and broadcast information data including the data of the selected service channel and the ESG are transmitted to the demodulation controller 240. The demodulation controller 240 then analyzes the MPE section data having the structure as shown in FIG. 4B to control time slicing and to perform error correction of data of the PID filtered service channels.

3 shows an example of the configuration of the protocol processing unit 120 of the DVB_H digital broadcast receiver.

Referring to FIG. 3, the protocol processor 120 classifies and outputs video, audio, and broadcast information data after processing IP and protocol information of the received selected service channel data. The video decoder 380 decodes the video data output from the protocol processor 120 and outputs the decoded video data to the display unit 150. The audio decoder 390 decodes the audio data output from the protocol processor 410 and outputs the decoded audio data to the speaker 155. The broadcast information data is transmitted to the control unit 100 to be decoded.

The protocol processor 120 may include an IP extractor 310, a UDP extractor 320, a FLUTE transmitter 330, and an RTP transmitter 340.

Referring to the configuration of the protocol processing unit 120, the data of the selected service channel input to the IP decapsule module 310, as shown in FIG. 4C, source IP address (source IP address, IP datagram that contains the desination IP address. The IP extractor 310 extracts IP information by decapsulating the IP datagram. In addition, the UDP decapsule module 413 receives UDP information including a source port address & destination port address (Scr Prt & Dst Prt) as shown in FIG. 4D. The UDP extractor 320 extracts the port information. Thereafter, if the UDP-removed protocol data is FLUTE / ALC protocol data as shown in FIG. 4E, the received data is transmitted to a FLUTE file transfer module (FLUTE) module 330. If the RTP protocol is used, the RTP transmission unit (A / V) is used. transport (RTP / TRCP) module 340. In the case of the FLUTE / ALC protocol, the data may be data (XML, SDP, HTML, JPG, POL, etc.) consisting of an ESG or a file, and the ESG and file data are transmitted to the control unit 100 and decoded. . In the case of the RTP protocol, the data may be audio and video data. In this case, the audio and video data may include data length, time stamp, and data. In the case of the video data, headers may be analyzed to distinguish between I and P frames. The video and audio data processed by the RTP protocol are transmitted to the corresponding video decoder 380 and the audio decoder 390, respectively, and decoded.

In this case, the controller 100 processes the protocols processed by the protocol processor 120. That is, the controller 100 may include an ESG engine (XML engine and ESG decoder), an SDP parser, a PSI / SI decoder, and the like, and include controllers and managers of the protocol information. Can perform process control and management functions of the protocol. The controller 100 processes each protocol information and data extracted and transmitted by the protocol processor 120. That is, the controller 100 may analyze PSI / SI information (NIT, SDT, EIT) extracted from the broadcast receiver 110 to check PSI / SI according to MPEG-2 and DVB-SI standards. The overall operation of the digital broadcast receiver is controlled by parsing the SDP (main data set related to broadcasting) of the ESG data. At this time, the service channel, ESG, audio and video data of each service channel are identified by PID, IP information, and port information. That is, the PSI / SI and SDP include tables defining identifiers of the service channel, audio, video, and ESG identifier information of each service channel. Accordingly, the control unit 100 may distinguish a service channel and / or audio data and / or video data and / or broadcast information data with reference to the PSI / SI decoding result and the SDT. The controller 100 may include a protocol processor 120.

In addition, the controller 100 controls a path of the broadcast receiver 110 and the protocol processor 120. Most of the MPEG-TS streams and IP datagrams shown in FIGS. 4A-4F consist of audio and video data. That is, when one burst data is received, most of the data constituting the burst data are video and audio data. Therefore, after analyzing the data of the received service channel, the controller 100 drives the corresponding component according to the result, and performs the path controller function of controlling the remaining components to connect the path. That is, if the received data is the MPE section as shown in FIG. 4B, the controller 100 drives the demodulation controller 240 to receive burst information, and the demodulation controller 240 analyzes the MPE section data to time slice and MPE-FEC functions. To do this. If the received data is IP V6, the controller 100 processes the IP list extracted by driving the IP extractor 310. If the received data is UDP, the controller 100 processes the port list extracted by driving the UDP extractor 320. If the received data is FLUTE / ALC, the controller 100 drives the FLUTE transfer unit 330 to process the ESG and / or files received thereafter. If the received data is RTP, the controller 100 drives the RTP transmitter 340 to process the RTP, and then transfers the video and audio data to the video decoder 380 and the audio decoder 390, respectively. Therefore, the controller 100 analyzes the received data to enable the corresponding component and controls the remaining components to provide only a path. At this time, the components providing the path perform a function of bypassing the received data, and thus can quickly process the received data.

When the protocol processor 120 outputs video data and audio data, the video decoder 380 decodes the video data and displays the video data on the display unit 150. The audio decoder 390 decodes the audio data and reproduces the audio data on the speaker 155. The video decoder 380 may use an H.264 or MPEG decoder, and the audio decoder 390 may use an AAC decoder. In the following description, the video decoder 380 is an example of an H.264 decoder.

In addition, the DMB broadcast receiver 100 may be configured only as a tuner and a demodulator. In this case, the final data output from the broadcast receiver 100 may be a packet stream of an MPEG-TS structure. In this case, the protocol handler 120 may be configured as a demultiplexer. The demultiplexer analyzes the PID included in the packet header in the received packet stream, selects packets of the selected service channel, and checks whether the PES header is included in the selected packets. In this case, the PES header includes information indicating that it is audio and video data. Accordingly, the demultiplexer may classify received packets into audio and video packets. In addition, the PES header includes time stamp information, so that the time offset for playing audio and video can be adjusted. In addition, the video packet may be analyzed to determine whether the corresponding video data is an I frame or a P frame.

Here, the operation of controlling the screen display when the service channel is changed in the DVB-H type digital broadcast receiver according to an embodiment of the present invention will be described.

First, the broadcast data output from the RTP transmitter 340 may be audio and video data, and the broadcast data may be composed of time stamps and variable length data. The variable length data may be audio or video data. The video data may be classified into I and P frame video data. That is, when the data of the video data is coded in the H.264 scheme, it has a structure consisting of 8-bit network abstraction layer (NAL) header and variable length video data as shown in Table 1 below.

NAL header  data

In the Table 1, the NAL header is composed of a 3-bit priority and a 5-bit NAL type. Analysis of the NAL type information can determine whether subsequent video data is an I frame or a P frame. Accordingly, when a channel change is requested through the key input unit 170, the controller 100 changes channel control information (PID, IP address, port address, etc. in the case of DVB-H) to set the changed service channel, and the broadcast receiver The PID of the changed service channel is set to 110. Then, the broadcast receiver 110 demodulates the broadcast data of the changed service channel and outputs the demodulated data to the protocol processor 120. The RTP transmitter 340 of the protocol processor 120 outputs the video data as shown in Table 1 below. At this time, the controller 100 examines the first I frame data received in the changed service channel. That is, when the controller 100 checks the NAL type of the video data received from the modified service channel and confirms that the video data is I frame video data, the controller 100 controls the video decoder 380 of the decoder to control the I frame video data. Decrypt. Then, the first I frame video data of the changed service channel decoded by the video decoder 380 is applied to the display unit 150 to reproduce the still picture.

In addition, time stamps of the video and audio data are not included every time. That is, as illustrated in FIG. 5A, the time stamp may be included and received in one burst period, and none may be received during a plurality of burst periods. In addition, since audio and video data must be synchronized with each other, the audio and video time stamps must be received, but only one type of time stamp may be received. Therefore, the audio and / or video timestamp information may not be received even when the broadcast data of the set size (here, the size of the broadcast data received in the burst period) is buffered. In this case, the synchronization of the playback time of the video and audio is not achieved. In this case, an embodiment of the present invention may use a method of playing the buffered video and audio data at predetermined time intervals until the synchronization is performed. To this end, in the embodiment of the present invention, the audio and video data are reproduced at a set speed using a local clock of the digital broadcast receiver until audio and video synchronization is performed in a state where buffered broadcast data of a set size is buffered. After that, when the time stamp is received, the audio and video playback operation is performed by adjusting the time offset of the audio and video.

6 is a flowchart illustrating a procedure of reproducing broadcast data when changing a channel according to an embodiment of the present invention. In the embodiment of the present invention described below, a case in which the digital broadcast receiver uses the DVB-H method will be described as an example.

Referring to FIG. 6, when the user selects another service channel through the key input unit 170 while watching a broadcast, the control unit 100 detects it in step 411 and control information for selecting the changed service channel in step 413. Set. The control information may be a PID, an IP address, a port address, and the like. At this time, the PID information is transmitted to the broadcast receiver 110, the PID filter 230 is set to the PID of the changed service channel. In addition, the controller 100 informs the broadcast receiver 110 of time slicing information for receiving burst data of the changed service channel. Then, the broadcast receiver 110 controls the power supply in the burst data section of the service channel set by the set time slicing information. Then, the broadcast receiver 110 selects and demodulates broadcast data of the changed service channel, and the demodulated broadcast data is applied to the protocol processor 120. Then, the protocol processor 120 processes the protocol of the broadcast data, classifies it as audio, video, and broadcast information, and delivers it to the corresponding decoders of the decoder 130.

In step 415, the controller 100 analyzes the video data of the changed service channel, checks the I-frame video data first received after the change, and displays the first I-frame video data on the display unit 150. FIG. 7 is a flowchart illustrating a procedure of identifying and displaying an I frame in step 415 of FIG. 6.

Referring to FIG. 7, when the video data classified by the protocol processor 110 is output after the service channel is changed, the controller 100 detects this in step 511 and analyzes the header of the received frame video data. Here, it is assumed that the received video data is data encoded by the H.264 method, and the video decoder 380 of the decoder 130 is an H.264 decoder. In this case, the video data output from the RTP transmitter 340 of the protocol processor 120 is composed of NAL tags and data as shown in Table 1, and the NAL tag has 5 bits of NAL type information. The NAL type information includes frame information indicating that the received video data is an I frame or a P frame. Therefore, the controller 100 checks whether the video data transmitted from the protocol processor 120 is the first I-frame video data received after the service channel is changed in step 513. Otherwise, the controller 100 does not buffer the video data received in step 515 (that is, skip) and analyze frame information of the next video data. When the first I-frame video data is received in the changed service channel performing the above operation, the controller 100 checks this in step 513, and in step 517 controls the video decoder 380 of the decoder 130 to receive the received I. Decoding the frame video data. The video decoder 380 then decodes the I frame video data of the received changed service channel under the control of the controller 100, and the decoded video data is transmitted to the display unit 150 for display.

As described above, the control unit 100 extracts and displays the first received I frame video data from the changed service channel when the service channel is changed, thereby displaying the broadcast signal of the changed service channel at the time of channel change. As described above, since the I frame video data is video data that can be decoded independently from the P frame and B frame video data, the I frame video data can be detected quickly and the broadcast of the changed service channel can be quickly reproduced. It is possible to shorten the screen display waiting time when changing the channel of the user. In the exemplary embodiment of the present invention, the first frame video data received after the change of the service channel is described. However, all received I frame data may be decoded and displayed.

When the first I frame received after the service channel change is detected as described above, video data of another frame received thereafter (which may be a P frame (which may include a B frame)) may also be decoded. Therefore, when the controller 100 checks the first I frame video data of the service channel changed in step 415 of FIG. 6, the controller 100 displays the same and buffers the I frame video data and subsequent received broadcast data in step 417. At this time, the buffering of the broadcast data includes audio and video data. When the broadcast data is buffered to the set buffer size while the broadcast data is buffered, the controller 100 decodes and reproduces the buffered audio and video data at a set speed in step 419.

The buffered broadcast data can be played in two stages. The audio and video data of the digital broadcast must be synchronized with the playback time. To this end, the video and audio data have playback time control information (time stamps) for determining a playback time, respectively, which may be DTS and PTS as described above. In this case, the time control information is not transmitted every time, but is irregularly transmitted. Therefore, in the embodiment of the present invention, once the amount of the buffered broadcast data reaches a set size, the audio and video data is reproduced at a set speed, and after the time stamp information is received, the time offset of the audio and video is adjusted. Play audio and video data normally.

FIG. 8 is a flowchart illustrating a playback procedure performed in steps 417 and 419 of FIG. 6.

Referring to FIG. 8, upon receiving the first I-frame video data received in the modified service channel, the controller 100 initializes a video input buffer (Vbcnt = 0) in step 551 and receives the received video data and audio data. Start storing the video and audio input buffers, respectively. The video and audio input buffers may be located at the front end of the video decoder 380 and the audio decoder 390, respectively. In step 553, the controller 100 checks whether the amount of video data buffered in the video input buffer is a set size (which may be the size of the video input buffer). The buffer size may be a burst size of the service channel, and may be a size that can be reproduced for 1 to 3 seconds in time. For example, a digital broadcast receiver using the DVB-H method displays 25 frames of video data per second. Therefore, the buffer size should be set to a size capable of buffering video data of 25 to 75 frames, and in the embodiment of the present invention, it is assumed that the video data is buffered for 2 seconds (about 50 frames). If the buffer size is not buffered as much as the buffer size, the control unit 100 detects this in step 553, stores the broadcast data (audio and video data) received in step 555 in a corresponding input buffer, and in step 557 the buffer. To increase the count. In step 559, the controller 100 controls to maintain the operation of displaying the I frame video data on the display unit 150.

If the buffer count value reaches the set size value of the video input buffer while buffering the received broadcast data while repeating the above operation, the control unit 100 detects it in step 553 and the audio decoder 390 in step 561. Control to decode the audio data stored in the audio input buffer. In step 573, the controller 100 checks the local clock of the digital broadcast receiver and sets the previous playback time to the current time. In this state, the time stamp information may be in a state that has not yet been received. In this case, the control unit 100 detects this in step 575 and confirms the current time of the digital broadcast receiver in step 577, and after adding the play interval (play_interval) to the last play time in step 579, the checked Compare with current time. If the current time is greater than or equal to the previous play time + play interval time value, the controller proceeds to step 581 to control to play the video data buffered in the video input buffer. Otherwise, the process returns to step 577. Wait

When buffering broadcast data having a predetermined size while displaying the I-frame video data as described above, the controller 100 checks the time (local time) of the digital broadcast receiver and plays the buffered audio and video data at the set time interval. To display. For example, if a DVB-H receiver reproduces 25 frames per second and the play_interval is 1 second, the controller 100 checks the local time of the digital broadcast receiver in steps 577 and 579. When the play interval time elapses from the play time (in this case, one second elapses after playing broadcast data), the video decoder 380 is controlled to play 25 frames of video data stored in the video input buffer for one second. Thereafter, the controller 100 changes the checked time to the previous playback time while performing steps 571 and 573. Therefore, while repeating the above process, the buffered broadcast data is reproduced according to the local time of the digital broadcast receiver until time stamp information is received. In this case, an offset may be generated in the reproduction time of the audio and video data.

In this case, the video data decoded by the video decoder 380 is applied to and displayed on the display unit 150. At this time, the audio signal is continuously reproduced through the audio decoder 390. Therefore, when the video and audio data are buffered more than the set size, the digital broadcast receiver according to the embodiment of the present invention plays back at the set speed with reference to the internal time of the digital broadcast receiver.

The time stamp information may be confirmed by RTCP delivered from the RTP transmitter 340. That is, when the RTCP is received, the time stamp of the video data can be checked. Therefore, if the RTCP is not received, the time stamp value cannot be checked. Therefore, the control unit 100 reproduces the audio and video data according to the time of the digital broadcast receiver while repeating steps 571 to 581. The RTCP is not transmitted in every burst. That is, two or more RTCPs may be included in one burst, and may not be included once while a plurality of bursts are received. In addition, the control unit 100 may receive both audio and video RTCP when receiving the RTCP to adjust the time offset of the audio and video. That is, the audio RTCP includes time information (audio DTS or PTS) for controlling the reproduction of the audio data, and the video RTCP includes time information (video DTS or PTS) for controlling the reproduction of the video data. Therefore, the control unit 100 receives the time stamp information of the audio and video, calculates a time offset of the two time information, and adjusts it to achieve reproduction synchronization of the audio and video data.

Accordingly, when the time stamp information is received in step 575, the controller 100 recognizes this in step 575, checks the offset of the two time stamp values in step 591, and adjusts the offset to achieve audio and video synchronization, and in step 593. The normal playback operation is performed while controlling the decoding time of the audio decoder 390 and the video decoder 380 (or an audio output buffer and a video output buffer, not shown), wherein each output buffer is a buffer for buffering decoded audio and video data.

As described above, when the service channel is changed, the digital broadcast receiver extracts the first I-frame video data received through the changed service channel and displays the still image, and buffers the received broadcast data. do. When the broadcast data is buffered to the set size, the digital broadcast receiver plays the buffered broadcast data with reference to the local time of the digital broadcast receiver until the time stamp information of the broadcast data is received, and the time stamp information is received. If the playback time offset of the audio and video data is adjusted, a normal playback operation is performed.

Here, the procedure of reproducing broadcast data in the local time of the digital broadcast receiver can be omitted. That is, in the state of displaying the first I-frame video data received on the changed service channel as a still picture, the apparatus waits until the time stamp information is received while reproducing the received audio signal. Thereafter, when the time stamp information is received to synchronize reproduction of audio and video data, a method of starting reproduction of the video data may be used.

Also, reproduction of the audio signal can be omitted in the state in which I frame video data is reproduced as a still picture before the time stamp information is received. In this case, before the audio and video are synchronized, the digital broadcast receiver may be in a state of displaying only a still picture of an I frame.

6 through 8 illustrate the DVB-H digital broadcast receiver as an example. However, the screen display method of the present invention as described above can be performed in the same manner in the DMB method. In this case, the demodulator of the broadcast receiver 110 does not include the PID filter 230 and the demodulation controller 240, and the protocol processor 120 may be configured as a demultiplexer. In this case, the information output from the broadcast receiver 110 may be a TS packet stream, and the demultiplexer may identify I frame video data by analyzing video PES information in the TS packet stream. Subsequent operations may be performed by the above procedure.

In addition, the above operation is described using a procedure of displaying a screen at a channel change time point as an example. However, when the digital broadcast receiver requests the first broadcast viewing, the same operation may be performed in the channel setting procedure. That is, the screen can be displayed in the same manner even when the channel is set when the digital broadcast receiver is driven.

The portable terminal may include a digital broadcast receiver configured and operated as described above. 9 is a diagram showing the configuration of a mobile terminal having the digital broadcast receiver as described above.

Referring to FIG. 9, in the case of a portable terminal having the digital broadcast receiver, the configuration of the portable terminal of the memory 160, the key input unit 170, the display unit 150, and the speaker 155 may be used. In addition, the controller 100 may control a communication function of the mobile terminal and at the same time perform a function of controlling the operation of the digital broadcast receiver. The wireless communication unit 190 may be configured as a frequency converter for converting the received radio signal to the falling frequency conversion and the transmitted radio signal to the frequency conversion. In addition, a data processor including a modulator for modulating a transmission signal and demodulating a reception signal and a codec for encoding a transmission signal and decoding a reception signal during the wireless communication may be configured in the wireless communication unit 190. You can also configure

The portable terminal having the configuration as described above, the operation of the digital broadcast receiver in the communication mode is off, and performs the RF communication function through the wireless communication unit 190. In the broadcast mode, the communication function becomes a standby state.

In the mobile terminal having the configuration described above, the digital broadcast receiver displays broadcast data of a service channel selected by a user, and when a communication channel with a service channel or a broadcaster is required, a digital broadcast receiver provides a return channel through the wireless communication unit 190. Can be formed.

The digital broadcast receiver may have a broadcast receiver 110, a protocol processor 120, a decoder 130, and the like as described above. When the service channel is set or changed in the digital broadcast receiver having the above configuration, the controller 100 changes the information of the set service channel and sets the service channel in the broadcast receiver 110 and the protocol processor 120. In this case, when the service channel is selected, the broadcast receiver 110 performs time slicing control to receive burst data of the selected service channels, checks the PID of the received burst data, and receives burst data of the set service channels. The processor 120 processes protocols of the received burst data. In this case, the controller 100 checks the first I-frame video data received in the selected service channel and displays the first I-frame video data on the display unit 150, and stores the received broadcast data in corresponding audio and video input buffers, respectively.

Thereafter, the controller 100 plays video data having a predetermined size by using a local time of the portable terminal, and this operation is repeatedly performed until time stamp information of the video and audio data is received. When the time stamp information of the audio and video is received, the controller 100 adjusts and synchronizes the time offset of the two data, and then controls a normal playback operation.

At this time, when an incoming call is generated while the screen is displayed, the controller 100 generates an alarm for the incoming call. In this case, the user may set the incoming alert mode, and the incoming call alert mode includes a general incoming alert and a silent incoming alert mode. When the general incoming alert is set, the controller 100 displays the incoming alert sound (melody, bell, music, etc.) set through the speaker 155, and displays the calling party subscriber information of the incoming call on the display unit 150. The silent incoming alert may be classified into a vibration alert and a display alert. When the vibration alert mode is set, when the incoming call is generated, the controller 100 drives a motor (not shown) to vibrate the portable terminal and displays the outgoing subscriber information of the incoming call on the display unit 150. When the display alert mode is set, when the incoming call is generated, the control unit 100 displays the calling party information of the incoming call along with a message for notifying that the incoming call is generated on the display unit 150. At this time, the incoming display displayed on the display unit 150 may be displayed by blinking. In this case, the incoming call information may be displayed on the display unit 150 while the video data of the service channel is displayed on the screen. In general, when the broadcast mode is performed, the user is watching a broadcast screen. Therefore, when the broadcast mode is set, a method of automatically setting the incoming call alert mode of the portable terminal to the display alert mode may be used.

In addition, the user of the mobile terminal may generate a call signal while displaying the screen of the selected service channel. That is, the digital broadcast has various service channels, and in this case, the broadcaster may require a request or response from the viewer during the broadcast. For example, in the case of a shopping service channel, a user needs a return communication channel to purchase a displayed product. In the service channels such as entertainment and games, the user can directly participate in a broadcast program. In this case, since the digital broadcast receiver performs unidirectional communication, it is preferable to communicate necessary information through the wireless communication unit 190. That is, the mobile terminal can perform a communication function through the wireless communication unit 190. In this case, the controller 100 may check information (for example, a phone number or IP information of a department that processes the corresponding program in the service channel) that can communicate with the service channel being broadcast. That is, when a DVH-H digital broadcast receiver is provided, the controller 100 may check telephone number and IP information related to a program of a corresponding service channel from the received ESG data. When the DMB digital broadcast receiver is provided, the controller 100 may check phone numbers and IP information related to a program of the corresponding service channel from the received EPG. Therefore, when the user of the mobile terminal selects the call function (that is, presses a call key), the wireless communication unit 190 establishes a communication channel with the corresponding service channel, and when the user generates call information (eg, purchase information, vote, etc.) The call information may be transmitted to the service channel side in broadcasting. The response result of the service channel being broadcast can be confirmed through the formed communication channel.

In this case, the user may position the cursor on the broadcast screen of the service channel to communicate with the key input unit 170 and request an outgoing call function. In this case, the controller 100 may know the location of the broadcast screen of the service channel displayed on the display unit 150 as described above. Therefore, when the user places the cursor at a specific position of the screen displayed on the display unit 150 and requests an outgoing communication function, the control unit 100 checks the position of the cursor on the display unit 100 and then checks the service channel and program information being broadcast. Thereafter, a dialing operation according to communication information (eg, a phone number, IP, etc.) corresponding to the program of the service channel may be performed.

When the call mode is performed in the broadcast mode as described above, the user may perform a communication function with the service channel being viewed in real time.

As described above, the broadcast channel received from the changed service channel or the set service channel can be quickly reproduced when the service channel is changed in the digital broadcast receiver or when the user starts watching the broadcast, thereby reducing the channel change time or the broadcast screen display time. Can be. In addition, the audio and video data can be reproduced in a state in which time synchronization of audio and video is not performed when switching channels, thereby increasing the display function of the digital broadcast receiver.

Claims (9)

In the screen display method of a digital broadcast receiver. Setting information of the changed broadcasting channel when changing the broadcasting channel; Analyzing video data received from the changed broadcast channel, displaying the video data as a still picture when receiving specific frame video data, and buffering the received broadcast data; Check whether the timestamp information of the buffered broadcast data is received, and if received, adjust the time offset of the audio and video to display synchronized video and audio, and otherwise perform the still image display process. The display method of the digital broadcast receiver. The method of claim 1, wherein the specific frame video data is I frame video data. The method of claim 2, wherein the displaying of the I frame video data further comprises reproducing the buffered audio data. In the screen display method of a digital broadcast receiver. Setting information of the changed broadcasting channel when changing the broadcasting channel; Analyzing the video data received from the changed broadcast channel and displaying the video data as a still picture when receiving specific frame video data; Buffering the received broadcast data and playing and displaying the buffered video and audio data using the local time of the digital broadcast receiver; When the time stamp information of the video and audio data is received, the screen display method of the digital broadcast receiver, characterized in that the step of adjusting and synchronizing the playback time offset of the video and audio being reproduced and performing the normal playback operation . The method of claim 4, wherein the specific frame video data is I frame video data. 6. The method of claim 5, wherein the playing of the video data using the local time controls to play the buffered set number of video frame data through a video decoder when the current local time and the playing time interval are reached. 7. The display method of the digital broadcast receiver. In the screen display method of a digital broadcast receiver. Setting information on the previously watched broadcast channel when a broadcast viewing request is made; Analyzing video data received from the broadcast channel and displaying the video data as a still picture when receiving specific frame video data; Buffering the received broadcast data and playing and displaying the buffered video and audio data using the local time of the digital broadcast receiver; When the time stamp information of the video and audio data is received, the screen display method of the digital broadcast receiver, characterized in that the step of adjusting and synchronizing the playback time offset of the video and audio being reproduced and performing the normal playback operation . 8. The method of claim 7, wherein the specific frame video data is I frame video data. The method of claim 8, wherein the playing of the video data using the local time controls to play the buffered set number of video frame data through a video decoder when the current local time and the playing time interval are reached. Display method of digital broadcast receiver

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