KR20010100292A - 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, comprising: a TS decoder for separating PSI data and primary and auxiliary audio service data from a transport stream, and PES decoding of primary and auxiliary audio service data separated by the TS decoder. A primary and an auxiliary audio PES processor for generating elementary streams of the primary and auxiliary audio services, and a primary and an auxiliary audio decoder for decoding the elementary streams of the primary and auxiliary audio services generated by the primary and auxiliary audio PES processors. A selector for selectively outputting an elementary stream of primary and secondary audio services generated by the primary and secondary audio PES processing units to the primary or secondary audio decoder according to an audio service selection signal SEL provided from the TS decoder; PSI decoupled from the TS decoder. The contents of the AC-3 descriptor contained in the PMT of the data are analyzed to determine whether the type of audio service of the broadcast program selected by the television receiver is a main audio service or an auxiliary audio service, and the identified main audio service or auxiliary audio service. A controller for providing a PID of a packet including an audio service to be selected to the TS decoder so that the TS decoder inputs a primary and an auxiliary audio service to the corresponding primary and auxiliary audio PES processing units respectively based on the PID; Include.

Description

AC-3 audio receiver of digital television system and processing method thereof {APPARATUS FOR RECEIVING AN AC-3 AUDIO IN A DIGITAL TELEVISION SYSTEM AND THE METHOD FOR PROCESSING THE SAME}

The present invention relates to a receiving apparatus of a digital television (hereinafter referred to as a digital TV), and more particularly, to an AC-3, which is an audio compression method employed in an ATSC (Advanced Television System Committe) system, which is a US digital TV broadcasting system. The present invention relates to an audio receiver of a digital television capable of simultaneously processing an audio service (main audio service) and an associated audio service (associated audio service).

In the digital TV broadcasting system, a digital TV broadcasting signal is compressed into a single packet by compressing audio and video data using a compression algorithm such as a Dolby AC-3 audio compression encoding algorithm or an MPEG-2 video compression algorithm. It is carried on a carrier in the form of a transport stream (TS) multiplexed on the extracted bit stream.

On the other hand, the receiver of the digital TV separates the audio data and the video data from the TS transmitted from the transmitting side, and then provides them to the corresponding audio and video decoders to restore the original decompressed audio and video signals. At this time, the receiver of the digital TV automatically tunes to a carrier including a program of a selected channel based on control data included in the packetized TS, and then demultiplexes only program information of a channel selected from the multiplexed and transmitted TS. By reconstructing, the program information is provided to the viewer.

Referring to Fig. 1, a block diagram of a receiver of a typical digital TV is shown. In the TS input to the receiving device of the digital TV, additional service data such as compressed audio, video data, system timing information, program specific information (PSI), and electric program guide (EPG) configured as packets are multiplexed into one bit stream. 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 including a forward error collection (FEC) and a demodulator performs error correction and demodulation on the input TS, and the TS decoder 22 in the demultiplexer 20 performs error correction and demodulation. Separates each video information, audio information, system timing information including PCR (program clock reference), PSI information including data such as PAT, PMT, NIT, CAT, and EPG (Electrical Program Guide) data from TS. . Video information, audio information, system timing information, and PSI and EPG information separated by the TS decoder 22 are transferred to the video buffer 24, the audio buffer 26, the clock recovery circuit 28, and the PSI decoder 50, respectively. Is provided.

The PSI decoder 50 finds information from which the audio or video packet of the broadcast program currently being broadcast can be selected from the input PSI data and the EPG data, that is, a PID which is a packet identification number. The PID information retrieved by the PSI decoder 50 is used to find elementary bit streams in the form of packets constituting a program such as audio and video data. Accordingly, the video and audio stream 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 the audio buffer 26, respectively. Restored as audio and video signals.

On the other hand, 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 provided 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 receiver having the above-described configuration is the most appropriate form of the current broadcasting service, and one type of audio and video data is included in one broadcast program.

Recently, ATSC (Advanced Television System Committe) method, which has been standardized and commercialized, is using Dolby AC-3 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 Service type Decoded service at the same time Main audio Complete Main (CM) Music & Effect & Dialogue VI, HI, C, VO Music & Effect (ME) Music & effects D Secondary 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 primary audio service consists of CM and ME so that music, sound effects, and voice services can be collectively available, while the auxiliary audio service is intended for special purpose audio services, for example for the visually impaired and the hearing impaired. It is configured to enable various services (D, C, VO) using services (VI, HI), emergency broadcast service (E), and voice multiplexing and simultaneous interpretation. In addition, the AC-3 standard stipulates that two primary and secondary audio services can be processed simultaneously so that a complete audio service can be provided only by a combination of primary and secondary services.

However, the AC-3 scheme can provide AC-3 audio service with substantially only the main service, and as shown in Fig. 1, a digital TV receiver of a type suitable for normal use is provided in one processing line, for example. It is structured to selectively accept primary audio service or secondary audio service. That is, only one type of audio service is configured to be processed so that the main and auxiliary services of AC-3 audio cannot be processed at the same time. Therefore, in order to process two audio services in a conventional manner, two demultiplexers must be used separately, resulting in a complicated system configuration and a problem in that a cost of a product increases.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and an object of the present invention is to provide an audio receiving apparatus of a digital television capable of simultaneously serving an AC-3 type audio service.

According to the present invention for achieving the above object, an audio receiving apparatus of an AC-3 system digital television system comprises: separating PSI data and main and auxiliary audio service data from the transport stream, and the main audio service and auxiliary audio; A TS decoder for generating an audio service selection signal SEL for selecting a service; A main audio PES processor configured to PES decode main audio service data separated from the TS decoder to generate an elementary stream of the main audio service; An auxiliary audio PES processor configured to PES decode 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 an elementary stream of an auxiliary audio service generated by the auxiliary audio PES processor; A selection unit for selectively outputting an elementary stream of primary and secondary audio services generated by the primary and secondary audio PES processing units according to the audio service selection signal (SEL) to the primary or secondary audio decoder; Analyze the contents of the AC-3 descriptor contained in the PMT of the PSI data separated from the TS decoder to determine whether the type of audio service of the broadcast program selected by the television receiver is a main audio service or an auxiliary audio service. Providing a PID of a packet including an audio service to be selected from a primary audio service or an auxiliary audio service to the TS decoder so that the TS decoder supports the primary and auxiliary audio services based on the PID, respectively; It characterized in that it comprises a control unit to be input to the processing unit.

According to another aspect of the present invention, a method for processing AC-3 main audio and auxiliary audio services of a digital television system includes: when one broadcast program is selected in the digital television, from the PMT (Program Map Table) information of the transport stream. Finding 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 langcod field of the AC-3 descriptor to select a language of a main audio service; Checking the asvcflag field of the AC-3 descriptor to find and provide all supplementary services related to the primary audio 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 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 receiver of a digital television system according to the present invention;

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

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

<Description of the symbols for the main parts of the drawings>

100: primary audio data path 200: secondary audio data path

140: primary audio decoder 240: secondary audio decoder

150: TS decoder 330: PSI decoder

300: control unit 500: demultiplexer

600: DRAM Queue

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

2, a block diagram of an audio receiver of a digital television constructed in accordance with the present invention is shown. In FIG. 2, the PMT in the TS input to the TS demultiplexer 500 is loaded with an AC-3 descriptor as illustrated in Table 2 below. The AC-3 descriptor is a type of service illustrated in Table 1. That is, information including a primary audio service and an auxiliary audio service is included, and is composed of a general syntax as shown in Table 2 below.

Syntax Number of bits ATSC purpose action descroptor_tagdescroptor_lengthsample_rate_codebsidbit_rate_codesurround_modebsmodnum_channelsfull_svclangcodif (num_channel == 0) / * 1 + 1 mode * / langcod2if (bsmod <2) {mainidreserved} else asvcflagstextlentext_codefor (i = 0; i <l; i ++) fortest <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, and bsmod is a field indicating a bit stream mode, and identifies AC-3 audio services by this field. In addition, full_svc indicates whether this audio service has all audio services or needs an auxiliary audio service, and lancod is a language code that allows the user to select a specific language for voice multicasting. do. The mainid field is a main audio ID, which exists only in the descriptor of the main audio service. If there are multiple main audio services, the mainid field is assigned a number for identifying each main audio service. This number is used in the asvcflag (associated service flag) field in the descriptors of the auxiliary audio services to connect the primary audio service with the auxiliary audio service.

The audio receiving apparatus of the present invention shown in FIG. 2 is configured to simultaneously process the main audio service and the auxiliary audio service by interpreting the AC-3 descriptors illustrated in Table 2. The demultiplexer 500 and the controller 300 , PSI decoder 330, primary audio decoder 140, and secondary audio decoder 240.

The demultiplexer 500 separates PSI data including PMT and video and audio data from a transport stream input from an FEC / modulator (not shown) based on PID data provided from the controller 300, and separates main audio and Each of the TS decoder 150 for outputting an audio service selection signal SEL for selecting the auxiliary audio and the main audio service data and the auxiliary audio data separately output from the TS decoder 150 may be externally connected to the corresponding main audio decoder ( Paired primary and secondary audio packetized elementary stream (PES) processors 110 and 210, primary and secondary audio temporary buffers 120 and 220, and primary and secondary audio decoder interfaces to 140 and secondary audio decoder 240. 130 and 230 and a single multiplexer 310 and packet buffer 320 interfaced between the aforementioned 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, and the auxiliary audio PES processing unit ( 210, auxiliary audio temporary buffer 220, auxiliary audio decoder interface 230 and auxiliary audio decoder 240 form auxiliary audio service path 200 of the present invention.

The primary and secondary audio PES processing units 110 and 210 PES decode the primary and auxiliary audio data separated by the TS decoder 150 to 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 operations of the respective audio decoders 140 and 240.

The packet buffer 320 has a function of compensating a difference in the operation speed between the external DRAM queue buffer 600 and the demultiplexer 500, and is selected from the primary and secondary audio PES processing units 110 and 210 selected through the multiplexer 310. The output data is temporarily stored and then output in synchronization with the operation of the external DRAM queue buffer 600.

The primary and auxiliary audio temporary buffers 120 and 220 receive primary 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. And supplied to primary and secondary audio decoders 110 and 210, respectively, connected to 130 and 230 to be restored as an audio signal.

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

The controller 300 interprets the contents of the AC-3 descriptor sent to the PMT provided by the PSI decoder 330 to determine the type of audio service transmitted along with the type of audio service of the currently selected broadcast program, that is, the main audio service, or Determine if it is an auxiliary audio service. The information grasped by the control unit 300 is provided to the user so that the user can select the audio services required by the user, and the control unit 300 sets the PID of the packet in which the corresponding audio service is loaded according to the audio service information selected by the user. The TS decoder 150 is provided to the TS decoder 150 so that the main and auxiliary audio services can be selectively input to the main audio PES processing unit 110 or the auxiliary audio PES processing unit 210 according to the PID.

The operation of the controller 300 described above is described in detail as follows with reference to the flowchart of FIG. 3.

In operation 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 selected broadcast from 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 the main audio data path 100, that is, the main audio PES processing unit 110, the multiplexer 310, and the packet buffer 320. ), The DRAM queue buffer 600, the main audio temporary buffer 120, the main audio interface 130, and the main audio decoder 140 are output to the user through a speaker (not shown) as an audio signal.

In the next step 420, the controller 300 finds and confirms the type of the main audio service, that is, the CM service or the ME service, by checking the bsmod field of the AC-3 descriptor.

In a subsequent step 430, in the case of a CM service, the langcod field is checked to find a language initially set in the CM service. The audio service thus found is provided to the user through the above-described main audio data path. In this regard, after all descriptors of the AC-3 main audio service are analyzed, the result is that all languages of the main audio service are displayed to the user to select the desired language. Thus, the main audio service data in the language selected by the user is output to the user through the main audio data path 100 described above.

Next, in step 440, the controller 300 checks the asvcflag field to find all auxiliary services related to 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 is, for example, an 8-bit register, and at each bit position, whether an auxiliary service retrieved from the asvcflag field, that is, VO, C_fsv, C, HI_fsv, HI, VI_fsv, VI, E, is an index signal. Is recorded as. The index in the service register 340 is used as data indicating whether or not the auxiliary service is being provided in the signal currently being broadcast. The presence or absence of the auxiliary service recorded in the service register 340 is displayed to the user in the monitor (not shown) via the video service data path (not shown) different from the audio service data path of the present invention, so that the user can select the auxiliary service desired therefrom. Make a choice.

In relation to the above-described step 440, when all the auxiliary services related to the CM service are found in the asvcflag field checked by the controller 300, if the E service exists among the auxiliary services, the E service is given priority over all the services. The primary audio service shall be replaced and output. Therefore, in the present invention, the control unit 300 facilitates recognition by assigning the most significant bit (MSB) of the service register 340 to a bit indicating the presence or absence of the E service.

Thereafter, when the user selects any auxiliary service he / she wants from the auxiliary service displayed on the monitor, the bsmod of the auxiliary service is registered in the corresponding position of the service register 340 in the control unit 300. By comparing the registered value with bsmod of the AC-3 descriptor, the PID decoder of the audio service having the AC-3 descriptor that matches the secondary service related to the CM service selected by the user may be used. 150 to select the service from the TS packet and control the multiplexer 320 to store the selected data in the DRAM queue buffer 600 (step 450). Accordingly, the auxiliary audio service selected by the user may include 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. Is provided to the user via.

On the other hand, in the above-described step 420, if the main audio service retrieved from the PMT by the control unit 300 is the ME service, since the D service is always present in the auxiliary service, the asvcflag field and the bsmod field while outputting the ME service. Check to find and output the D service among the auxiliary services (step 460). In this case, like the CM service, a desired language may be selected using the langcod field (step 470).

As described above, by configuring a path capable of simultaneously processing the main audio service and the auxiliary audio service in the demultiplexer without adding a separate demultiplexer in the receiving device using the AC-3 method of terrestrial digital TV broadcasting. In addition, the unit cost of the digital TV broadcasting receiver can be lowered without any additional cost, and since the manufacturing can be made with a simpler structure, it can be applied to a compact system such as a PC card in the future.

Claims (3)

An audio receiving apparatus for finding and restoring an audio stream from a transport stream transmitted from a transmission side in a digital television system using an AC-3 system. A TS decoder for separating PSI data and primary and auxiliary audio service data from the transport stream and generating an audio service selection signal (SEL) for selecting the primary and secondary audio services; A main audio PES processor configured to PES decode main audio service data separated from the TS decoder to generate an elementary stream of the main audio service; An auxiliary audio PES processor configured to PES decode 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 an elementary stream of an auxiliary audio service generated by the auxiliary audio PES processor; A selection unit for selectively outputting an elementary stream of primary and secondary audio services generated by the primary and secondary audio PES processing units according to the audio service selection signal (SEL) to the primary or secondary audio decoder; Analyze the contents of the AC-3 descriptor contained in the PMT of the PSI data separated from the TS decoder to determine whether the type of audio service of the broadcast program selected by the television receiver is a main audio service or an auxiliary audio service. Providing a PID of a packet including an audio service to be selected from a primary audio service or an auxiliary audio service to the TS decoder so that the TS decoder supports the primary and auxiliary audio services based on the PID, respectively; An audio receiving device of a digital television system using the AC-3 system, characterized in that it comprises a control unit for inputting to a processing unit. The apparatus of claim 1, wherein the audio receiving device is: Temporarily storing the primary or elementary stream selectively output from the selection unit, and synchronizing the temporarily stored elementary stream with the decoding operation of the primary and secondary audio decoders according to the audio selection signal SEL to perform the primary or secondary stream. An audio receiver of a digital television system using the AC-3 system, characterized by further comprising a packet buffer output to an audio decoder. Main audio and auxiliary audio services of a digital television system having a main audio processing means and an auxiliary audio processing means for decoding AC-3 system main audio service data and auxiliary audio service data extracted from a transport stream transmitted from a transmitting side, respectively. In the processing method, If one broadcast program is selected in the digital television, finding all AC-3 descriptors related to the selected broadcast from PMT (Program Map Table) information of the transport stream; Checking a bsmod field of the found AC-3 descriptor to identify a CM or ME service as a main audio service; Checking a langcod field of the AC-3 descriptor to select a language of a main audio service; Checking the asvcflag field of the AC-3 descriptor to find and provide all supplementary services related to the primary audio 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 the user. How the system handles AC-3 audio.