KR100329830B1 - Apparatus for receiving an ac-3 audio in a digital television system and the method for processing the same - Google Patents

Abstract

The present invention relates to an audio receiving apparatus of a digital television system, and more particularly, to a TS decoder for separating PSI data and primary audio data and auxiliary audio data from a transport stream, A primary and secondary audio PES processing unit for generating an elementary stream of primary and secondary audio services, a primary and secondary audio decoder for decoding elementary streams of primary and secondary audio services generated by said primary and secondary audio PES processing units, A selector for selectively outputting the elementary streams of the main and auxiliary audio services generated by the main and auxiliary audio PES processing units to the main or auxiliary audio decoder in accordance with the audio service selection signal SEL provided from the TS decoder, , A PSI demultiplexed from the TS decoder The content of the AC-3 descriptor included in the PMT of the data is analyzed to determine whether the type of the audio service of the broadcast program selected in the television receiver is the main audio service or the auxiliary audio service, To the TS decoder so that the TS decoder inputs the main and auxiliary audio services to the corresponding main and auxiliary audio PES processing units on the basis of the PID, .

Description

TECHNICAL FIELD [0001] The present invention relates to an AC-3 audio receiving apparatus and a processing method therefor,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a receiving apparatus for a digital television (hereinafter referred to as a digital TV), and more particularly to a receiving apparatus for a digital television To an audio receiving apparatus of a digital television capable of simultaneously processing a main audio service and an associated audio service.

In the digital TV broadcasting system, the digital TV broadcasting signal compresses audio and video data using a compression algorithm, for example, a Dolby AC-3 audio compression coding algorithm or an MPEG-2 video compression algorithm, And transmitted on a carrier wave in the form of a transport stream (TS) multiplexed onto a bit stream.

On the other hand, in a receiver of a digital TV, audio data and video data are separated from a TS transmitted from a transmission side, and then supplied to corresponding audio and video decoders, respectively, to restore original decompressed audio and video signals. At this time, the receiver of the digital TV automatically tunes to the carrier wave including the program of the selected channel based on the control data included in the packetized TS, and demultiplexes only the program information of the selected channel from the multiplexed TS And provides the program information to the viewer by reconstructing the program information.

Referring to Fig. 1, a block diagram of a typical digital TV receiving apparatus is shown. In a TS input to a receiving device of a digital TV, supplementary service data such as compressed audio, video data, system timing information, Program Specific Information (PSI), and EPG (Electrical Program Guide) have.

The digital TV receiver shown in FIG. 1 includes a channel unit 10, a demultiplexer 20, a PSI decoder 50, a video decoder 60, and an audio decoder 70. The demultiplexer 20 also includes a TS decoder 22, a video buffer 24, an audio buffer 26, and a clock recovery circuit 28.

The channel unit 10 composed of a forward error correction (FEC) and a demodulator performs an error correction and demodulation process on an input TS, and the TS decoder 22 in the demultiplexer 20 performs error correction and demodulation The TS separates the video information, audio information, system timing information including a PCR (program clock reference), PSI information including data such as PAT, PMT, NIT and CAT, and EPG (Electrical Program Guide) data . The video information, audio information, system timing information and PSI and EPG information separated by the TS decoder 22 are supplied to the video buffer 24, the audio buffer 26, the clock recovery circuit 28 and the PSI decoder 50 / RTI >

The PSI decoder 50 finds information for selecting audio or video packets of a broadcast program currently broadcasted from the input PSI data and EPG data, that is, a PID which is a packet recognition number. The PID information retrieved from the PSI decoder 50 is used to find packet-type elementary bit streams constituting one program such as audio and video data. The video and audio streams separated by the TS decoder 22 by the PID information are provided to the video decoder 60 and the audio decoder 70 via the corresponding video buffer 24 and audio buffer 26 respectively And restored as audio and video signals.

Meanwhile, the clock recovery circuit 28 in the demultiplexer 20 processes the separated system timing information to recover the PCR clock to generate a system time clock (STC). The STC information generated by the clock recovery circuit 28 is supplied to the video decoder 60 and the audio decoder 70 and used as a signal for synchronizing the reproduction timing of the video data and the audio data.

The digital television receiving apparatus of the above-described configuration is one of the most appropriate forms in the current broadcasting service, and one type of audio and video data is composed of one type of broadcasting program.

In the US Advanced Television System Committee (ATSC) system, which has recently been standardized and commercialized, Dolby AC-3 is adopted as an audio compression method. In the AC-3 scheme, audio data is divided into a main audio service and an associated audio service as shown in Table 1 below.

service Type of service Concurrently decoded services Main audio Complete Main (CM) Music Effect Dialogue VI, HI, C, VO Music Effect (ME) Music Effects D Auxiliary audio Visually Imapired (VI) Narrative Description CM Hearing Impaired (HI) Dialogue with Enhanced Intelligility CM Dialogue (D) Dialogue ME Commentary (C) Optional Program Commentary CM Emergency (E) Emergency High Priority Announcements _ Voice-Over (VO) Voice Over CM

As illustrated in Table 1, the main audio service is composed of CM and ME, and music, sound effect, and voice service are collectively available, while auxiliary audio service is used for special purpose audio services such as blind and hearing-impaired (D, C, VO) using services (VI, HI), emergency broadcasting service (E) and voice multiplexing and simultaneous interpretation. In addition, the AC-3 standard requires that two main and auxiliary audio services be processed simultaneously so that a complete audio service can be provided only by a combination of main and auxiliary services.

However, the AC-3 scheme can provide an AC-3 audio service substantially only with the main service, and a digital TV receiver of a type suitable for normal use as shown in FIG. 1 is one processing line, , A main audio service, or an auxiliary audio service. That is, it is configured to process only one type of audio service, so that the main service and the auxiliary service of AC-3 audio can not be processed at the same time. Therefore, in order to process two audio services in a conventional manner, two demultiplexers must be used separately, which complicates the configuration of the system and raises the cost of the product.

It is an object of the present invention to provide an audio receiving apparatus for a digital television capable of simultaneously serving an audio service of an AC-3 system.

According to an aspect of the present invention, there is provided an audio receiving apparatus of an AC-3 system digital television system, comprising: a main audio service unit for separating PSI data and primary audio data from the transport stream, A TS decoder for generating an audio service selection signal SEL for selecting a service; A main audio PES processor for PES decoding the main audio service data separated from the TS decoder to generate an elementary stream of the main audio service; An auxiliary audio PES processor for PES decoding the auxiliary audio service data separated from the TS decoder to generate an elementary stream of the auxiliary audio service; A main audio decoder for decoding the elementary stream of the main audio service generated by the main audio PES processing unit; An auxiliary audio decoder for decoding the elementary stream of the auxiliary audio service generated by the auxiliary audio PES processing unit; A selector for selectively outputting the elementary streams of the main and auxiliary audio services generated by the main and auxiliary audio PES processing units according to the audio service selection signal SEL to the main or auxiliary audio decoder; Analyzes the content of the AC-3 descriptor included in the PMT of the PSI data separated from the TS decoder to determine whether the type of the audio service of the broadcast program selected in the television receiver is the main audio service or the auxiliary audio service, Providing a PID of a packet containing an audio service to be selected from among the main audio service or the auxiliary audio service to the TS decoder so that the TS decoder can decode the primary and secondary audio PES And a control unit for inputting the data to the processing unit.

According to another aspect of the present invention, there is provided a method of processing AC-3 main audio and auxiliary audio services of a digital television system, comprising: when one broadcast program is selected in the digital television, Searching for all AC-3 descriptors associated with the selected broadcast; Checking a bsmod field of the found AC-3 descriptor to identify a CM or ME service as a main audio service; Checking a lang cod field of the AC-3 descriptor to select a language of the main audio service; Checking the asvcflag field of the AC-3 descriptor to find all auxiliary services associated with the primary audio service and providing the auxiliary service to the user;

Checking whether the auxiliary service selected by the user exists in the auxiliary service related to the main audio service, and selecting the auxiliary audio service having the checked AC-3 descriptor to serve to the user.

1 is a schematic block diagram of an audio receiver of a digital television system according to the prior art,

2 is a block diagram of an audio receiving apparatus of a digital television system according to the present invention;

3 is a diagram illustrating a configuration of a service register in the control unit shown in FIG. 2,

4 is a flowchart illustrating a process of processing AC-3 format audio data performed in an audio receiving apparatus of a digital television system according to the present invention.

Description of the Related Art

100: main audio data path 200: auxiliary audio data path

140: main audio decoder 240: auxiliary audio decoder

150: TS decoder 330: PSI decoder

300: control unit 500: demultiplexer

600: DRAM queue

Hereinafter, the operation of the preferred embodiment according to the present invention will be described in detail with reference to the accompanying drawings.

2, a block diagram of an audio receiving apparatus of a digital television constructed in accordance with the present invention is shown. 2, an AC-3 descriptor as illustrated in the following Table 2 is carried on the PMT in the TS input to the TS demultiplexer 500. The AC-3 descriptor includes the service type Information for distinguishing between the main audio service and the auxiliary audio service, and is composed of the syntax as shown in Table 2 below.

Syntax Number of bits ATSC purpose action i = 0; i <M; i ++) {test [l]} for (l = 0; l) = 1 + 1 mode * / langcod2if (bsmod <2) {mainidreserved} else asvcflagstextlentext_codefor (num_channel == 0) <N; l ++) {additional_info [l] 8835623418358718Nx8 "000" ("01000")? Unused CompareCounting__Latch in register_CompareLatch in registerCompareCompareCompare_Compare____

In Table 2, descriptor_tag is a field for identifying whether this descriptor is an AC-3 audio descriptor, bsmod is a field for indicating a bit stream mode, and this field identifies AC-3 audio services. Also, full_svc indicates whether the audio service has all audio services or an auxiliary audio service, and lancod is a language code, which allows a user to select a specific language broadcast in a voice multiplex broadcasting. do. The mainid field is the main audio ID, which is present only in the descriptor of the main audio service. If there are a plurality of main audio services, a number for identifying each main audio service is assigned. This number is used in the asvcflag (associated service flag) field in the descriptor of the auxiliary audio services to perform the function of connecting the main audio service to the auxiliary audio service.

2 is configured to simultaneously process the main audio service and the auxiliary audio service by analyzing the AC-3 descriptor illustrated in Table 2. The demultiplexer 500, the controller 300, A PSI decoder 330, a main audio decoder 140, and an auxiliary audio decoder 240.

The demultiplexer 500 demultiplexes the PSI data including the PMT and the video and audio data from the transport stream input from the FEC / modulator (not shown) based on the PID data provided from the control unit 300, A TS decoder 150 for outputting an audio service selection signal SEL for selecting auxiliary audio and a main audio service data and an auxiliary audio data separately outputted from the TS decoder 150 are supplied to a corresponding main audio decoder Main and auxiliary audio PES (Packetized Elementary Stream) processing units 110 and 210, main and auxiliary audio temporary buffers 120 and 220, main and auxiliary audio decoder interfaces 140 and 140, and auxiliary audio decoder 240, A single multiplexer 310 and a packet buffer 320 interfaced between the multiplexers 130 and 230 and the above described pairs. The main audio PES processing unit 110, the main audio temporary buffer 120, the main audio decoder interface 130 and the main audio decoder 140 form the main audio service path 100 of the present invention, 210, auxiliary audio temporary buffer 220, auxiliary audio decoder interface 230 and auxiliary audio decoder 240 form the auxiliary audio service path 200 of the present invention.

The main and auxiliary audio PES processing units 110 and 210 PES-decode the main and auxiliary audio data separated by the TS decoder 150 and output an elementary stream of each audio service. These elementary streams are sent to the external DRAM queue buffer 600 through the packet buffer 320 and buffered according to the operation of the audio decoders 140 and 240.

The packet buffer 320 has a function of compensating for a difference in operation speed between the external DRAM queue buffer 600 and the demultiplexer 500 and is provided to the main and auxiliary audio PES processing units 110 and 210 selected through the multiplexer 310 Temporarily stores any one of the output data, and outputs the output data in synchronization with the operation of the external DRAM queue buffer 600.

The main and auxiliary audio buffers 120 and 220 receive the main or auxiliary audio data provided from the external DRAM queue buffer 600 under the control of the audio service selection signal SEL of the TS decoder 150, To the main and auxiliary audio decoders 110 and 210, respectively, connected to the audio signal processors 130 and 230, so that they are restored as audio signals.

The PSI decoder 330 decodes the PSI data separated by the TS decoder 150 to generate a PMT having an AC-3 descriptor, and provides the generated PMT to the controller 300.

The controller 300 interprets the contents of the AC-3 descriptor sent in the PMT provided by the PSI decoder 330 and determines whether the type of the audio service transmitted together with the type of the audio service of the currently selected broadcast program, Determine if it is a secondary audio service. The control unit 300 provides the information identified by the control unit 300 to the user so that the user can select audio services required by the user. The control unit 300 determines a PID of a packet on which the corresponding audio service is loaded according to the audio service information selected by the user TS decoder 150 so that the TS decoder 150 selectively inputs the main and auxiliary audio services to the main audio PES processing unit 110 or the auxiliary audio PES processing unit 210 according to the PID.

The operation of the control unit 300 described above will be described in detail as follows with reference to the flowchart of FIG.

In step 410, when one broadcast program is selected in the audio receiver of the digital TV, the controller 300 searches for all AC-3 descriptors related to the broadcast selected from the PMT or EPG data. Of course, at this time, the main audio data of the broadcast selected by the PID of the audio data retrieved from the elementary stream in the PMT is supplied to the main audio data path 100, i.e., the main audio PES processing unit 110, the multiplexer 310, (Not shown) as an audio signal via the DRAM queue buffer 600, the main audio temporary buffer 120, the main audio interface 130, and the main audio decoder 140, as shown in FIG.

In the next step 420, the control unit 300 checks the bsmod field of the AC-3 descriptor to find and check the type of the main audio service, that is, the CM service or the ME service.

In the subsequent step 430, if it is a CM service, the langcod field is checked to find a language set at the beginning of the CM service. And provides it to the user through the above-described main audio data path using the audio service thus found. In this regard, all the descriptors of the AC-3 main audio service are analyzed, and as a result all languages of the main audio service are displayed to the user, thereby selecting the desired language. Thus, the main audio service data is output to the user via the main audio data path 100 described above in the language selected by the user.

In the next step 440, the control unit 300 checks the asvcflag field to find all the auxiliary services associated with the CM service. The data of the auxiliary service retrieved from the asvcflag field is recorded in the service register 340 in the control unit 300 shown in detail in FIG. The service register 340 determines whether or not auxiliary services retrieved from the asvcflag field, for example, VO, C_fsv, C, HI_fsv, HI, VI_fsv, VI, Lt; / RTI &gt; The index in the service register 340 is used as data indicating whether or not the auxiliary service is currently being provided in the signal to be broadcasted. The presence or absence of ancillary services recorded in the service register 340 is displayed to a user on a monitor (not shown) via an audio service data path of the present invention and a video service data path (not shown) To be selected.

In the above step 440, when all the auxiliary services related to the CM service are found in the asvcflag field checked by the control unit 300, if there is an E service among the auxiliary services, It should be replaced with the main audio service. Accordingly, in the present invention, the most significant bit (MSB) of the service register 340 is allocated to a bit indicating the presence or absence of the E service, thereby allowing the control unit 300 to easily recognize the service.

Then, when the user selects any desired auxiliary service from the auxiliary service displayed on the monitor, the control unit 300 registers the bsmod of the auxiliary service in the corresponding position of the service register 340 in the control unit 300 , Compares the thus registered value with the bsmod of the AC-3 descriptor, and outputs the PID value of the audio service having the AC-3 descriptor matching the auxiliary service related to the CM service selected by the user to the TS decoder 150 to select the service in the TS packet and to control the multiplexer 320 to store the selected data in the DRAM queue buffer 600 (step 450). Accordingly, the selected auxiliary audio service is provided to the user through the auxiliary audio data path, that is, the packet buffer 320, the DRAM queue buffer 600, the auxiliary audio temporary buffer 220, the auxiliary audio interface 230 and the auxiliary audio decoder 150, To the user.

If the main audio service retrieved from the PMT by the control unit 300 is an ME service, the D service is always present in the auxiliary service. In this case, since the ME service is output and the asvcflag field and the bsmod field And searches for and outputs the D service of the auxiliary service (step 460). At this time, the desired language can be selected using the langcod field as in the CM service (step 470).

As described above, it is possible to construct a path for simultaneously processing the main audio service and the auxiliary audio service in the demultiplexer without adding a configuration of a separate demultiplexer in the receiving apparatus using the AC-3 scheme of terrestrial digital TV broadcasting , It is possible to reduce the unit price of the digital TV broadcast receiving apparatus without burdening the additional cost, and it is possible to manufacture the apparatus with a simpler structure, so that it can be applied to a compact system such as a PC card in the future.

Claims (3)

An audio receiving apparatus for searching and restoring an audio stream from a transport stream transmitted from a transmission side in a digital television system using an AC-3 scheme, A TS decoder for separating PSI data and primary and secondary audio service data from the transport stream and generating an audio service selection signal SEL for selecting the primary audio service and the secondary audio service; A main audio PES processor for PES decoding the main audio service data separated from the TS decoder to generate an elementary stream of the main audio service; An auxiliary audio PES processor for PES decoding the auxiliary audio service data separated from the TS decoder to generate an elementary stream of the auxiliary audio service; A main audio decoder for decoding the elementary stream of the main audio service generated by the main audio PES processing unit; An auxiliary audio decoder for decoding the elementary stream of the auxiliary audio service generated by the auxiliary audio PES processing unit; A selector for selectively outputting the elementary streams of the main and auxiliary audio services generated by the main and auxiliary audio PES processing units according to the audio service selection signal SEL to the main or auxiliary audio decoder; Analyzes the content of the AC-3 descriptor included in the PMT of the PSI data separated from the TS decoder to determine whether the type of the audio service of the broadcast program selected in the television receiver is the main audio service or the auxiliary audio service, Providing a PID of a packet containing an audio service to be selected from among the main audio service or the auxiliary audio service to the TS decoder so that the TS decoder can decode the primary and secondary audio PES And a control unit for controlling the AC-3 to input the audio signal to the audio processing unit. The audio receiving apparatus according to claim 1, further comprising: And an audio decoder for temporarily storing the main or elementary stream selectively output from the selector and synchronizing the temporarily stored elementary stream with the decoding operation of the main and auxiliary audio decoders in accordance with the audio selection signal SEL, Further comprising a packet buffer for outputting the audio signal to an audio decoder. A main audio and auxiliary audio service of a digital television system having main audio processing means and auxiliary audio processing means for decoding main audio service data and auxiliary audio service data of the AC-3 system extracted from the transport stream transmitted from the transmission side, In the processing method, Searching for all AC-3 descriptors related to the selected broadcast from PMT (Program Map Table) information of the transport stream when one broadcast program is selected on the digital television; Checking a bsmod field of the found AC-3 descriptor to identify a CM or ME service as a main audio service; Checking a lang cod field of the AC-3 descriptor to select a language of the main audio service; Checking the asvcflag field of the AC-3 descriptor to find all auxiliary services associated with the primary audio service and providing the auxiliary service to the user; Checking whether an auxiliary service selected by the user is present in an auxiliary service related to the primary audio service, and selecting an auxiliary audio service having the checked AC-3 descriptor to service the user. AC-3 audio processing method of the system.