KR20050076131A - Method of decoding of main audio source and associated audio source through iec958 - Google Patents

Abstract

The present invention relates to a method of decoding a main audio source and an associated audio source transmitted to IC958, comprising: a) selecting a predetermined bit value in a field indicating information on AC-3 data among headers included in an AC-3 data burst; Receiving AC-3 audio data decoded in the IEC-958 SPDIF format including at least one of main audio data and related audio data separated using the same, and b) processing the decoded AC-3 audio data. Determining a predetermined mode for the data; and c) processing the data according to the corresponding mode selected in the step b).

Description

Method of decoding main audio source and related audio source transmitted to IC958 {Method of Decoding of Main Audio Source and Associated Audio Source through IEC958}

The present invention relates to a method of decoding a main audio source and an associated audio source transmitted to IC958. More specifically, when terrestrial ATSC broadcasting or digital audio data includes a main audio source and an associated audio source, it is simultaneously output in IEC958 form. And a method for decoding and storing audio / video receivers and digital audio storage media (memory cards, hard disks).

1 is a block diagram of an audio stream coded with AC-3.

In this embodiment, the audio stream includes sync information, bit stream information, audio block and CRC.

Referring to FIG. 1, an audio compression method used in ATSC terrestrial broadcasting is AC-3, and an audio stream coded with AC-3 includes a synchronization information header, a bit stream information header, It consists of a total of six audio blocks with 256 audio samples along with CRC information.

The synchronization information is located at the beginning of each frame and is necessary information for synchronization. Bit stream information is information following synchronization information and has an audio service content. In the bit stream information, there is a parameter indicating information about a service type of 'Bsmod' audio.

2 and 3, Bsmod distinguishes whether audio data is a main source or related source information.

An audio decoder that processes audio streams of ATSC broadcasting may need to simultaneously process two audio streams. Most broadcast audio programs are the main audio service, but use the associated audio service as a narrator broadcast for the visually impaired. In this case, the audio decoder sequentially decodes each stream, mixes each other in units of frames, and finally outputs sound.

When receiving the ATSC terrestrial broadcast and decoding the AC-3 audio data and outputting the AC-3 audio data in the IEC-958 SPDIF format to the audio output terminal, the audio data format is shown in FIG. 4. An AC-3 bitstream consists of a sequence of AC-3 frames. The data type of the AC-3 data burst is '1' (AC-3). One AC-3 frame represents 1536 audio samples encoded. Data bursts have a burst preamble as a header, followed by a burst payload. The burst payload of every data burst must contain a complete AC-3 frame.

The length of an AC-3 data burst is determined by the encoding bit rate.

4 shows a form of an AC-3 data burst, in which a data burst including an AC-3 frame should be transmitted at a constant rate. The burst preamble is 64 bits in total, and each of the preambles Pa, Pb, Pc, and Pd is all 16 bits. Pa and Pb are 0xF872 and 0x4E1F as SYNC information, respectively. Pd represents the length of the AC-3 burst-payload. Pc represents information on AC-3 data, the content of which is as shown in FIG.

The data stream number is information indicating which data burst the bitstream belongs to. For eight independent data streams from 0 to 7, each stream is transmitted by IEC958 in a time multiplexed manner. If a single stream of data is sent in IEC958's Consumer mode, the data stream number is '0'. If several main audio services and related audio services are transmitted simultaneously, the main audio service should be '0'. If the audio / video receiver can only handle a single data bit stream, it will only receive and process the data stream number '0'. The priority of the data stream number means that '0' is the highest.

An object of the present invention is to output an audio stream and other digital audio data received from an ATSC terrestrial digital television broadcast to an audio / video receiver in the IEC958 SPDIF format or to a digital audio storage medium when there are several main audio services and related audio services. It is to provide IEC958 transmission method when saving to (memory card, hard disk).

In order to achieve the above object, a method of decoding a main audio source and a related audio source transmitted to IC958 of the present invention includes: a) a predetermined field in a field indicating information on AC-3 data among headers included in an AC-3 data burst; Receiving AC-3 audio data decoded in the IEC-958 SPDIF format including at least one of main audio data or related audio data separated using the bit value of the portion; b) the decoded AC-3 Determining a predetermined mode for processing the audio data; and c) processing the data according to the corresponding mode selected in the step b).

In the present invention, it is preferable that the predetermined part of the bits in the field indicating the information on the AC-3 data of step a) is a storage area bit.

In the present invention, a method of classifying information using AC bit data using a predetermined bit value may include a value of 0 when the storage area bit is main audio data, and a value of 1 when related audio data is used. It is desirable to store the values and distinguish them.

In the present invention, the predetermined mode of step b) preferably includes a main audio service mode, a main and related audio service mode, and an associated audio service mode.

In the present invention, when the main audio service is selected in step b), if the audio video receiver can decode only a single stream in step c), the data stream number is 0 by default, and one of the data stream numbers from 0 to 7 is processed. It is desirable to be able to select the main audio service.

The present invention preferably allows the user to select as many streams as possible if the audio video receiver is capable of multi-stream decoding in step c) when selecting the main audio service in step b).

The present invention preferably stores only the main audio service if data is stored in the digital audio storage medium in step c) when the main audio service is selected in step b).

In the present invention, when selecting the main and related audio service in step b), step c) processes that the data stream number is 0 by default if the audio and video receiver can decode only a single stream. It is desirable to be able to select your own audio service.

In the present invention, when the main and related audio services are selected in step b), it is preferable that step c) outputs all streams by sequentially decoding the main audio stream and the related audio services if the audio video receiver is capable of multi-stream decoding.

In the present invention, when the main and related audio services are selected in step b), if step c) stores data in the digital audio storage medium, it is preferable to store all the received main audio services and related audio services.

In the present invention, when selecting the relevant audio service in step b), step c) processes the data stream number to be zero by default if the audio and video receiver can decode only a single stream, and associates one of the data stream numbers from 0 to 7 by default. It is desirable to be able to select an audio service.

Preferably, the present invention allows step c) to allow the user to select as many streams as possible if the audio video receiver is capable of multi-stream decoding when selecting the relevant audio service in step b).

The present invention preferably stores only the associated audio service if step c) stores the data on the digital audio storage medium when the related audio service is selected in step b).

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

5 illustrates a related service bit structure of a Pc preamble according to an embodiment of the present invention.

In the above embodiment, the Pc preamble is designated as a related service using the fifth reserved bit.

Referring to FIG. 5, one bit of the storage bits of the preamble Pc is used as a bit related to a related service. The fifth reserved bit of the Pc preamble is used to indicate whether the bitstream of the current data burst is an associated audio service. If the fifth preserved bit is defined as 'related service', a value of '1' means that the bitstream is an associated audio service, and a value of '0' means that the bitstream is a main audio service.

In addition, an audio / video receiver or a digital audio storage medium may use the associated service bits to select a decoding method and a storage method.

In general, when an audio / video receiver receives an audio bitstream in IEC958 format, if multiple audio bitstreams exist, the audio stream is decoded in order to generate a voice output. However, if the receiver can only process a single stream, the bitstream number Decode only streams that are '0'. Therefore, the main audio service should have a bitstream number of '0'. For IEC958 multi-audio data bursts with multiple main audio services and related audio services, only one of the main audio services has a bitstream number of '0' and the rest of the main audio and related services have a value of 1-7. Have Therefore, a receiver capable of processing only one bitstream cannot process the remaining main audio services whose bitstream number value is not '0'. Also, if there is a main audio service whose bitstream number value is not '0', it cannot be distinguished whether it is related audio service or one of main audio services.

Therefore, by using the information bits for the related service, the main audio service whose bitstream number is not '0' can be determined as one of the main audio services without unconditionally determining the related audio service. In addition, since the distinction between the main audio service and the related audio service is clear, the user can selectively process only a desired service and decode or store only a service of a specific bitstream number among desired service modes.

FIG. 6 illustrates a structure in which an associated service bit is applied to Pc in a header of a data burst of AC-3 according to an embodiment of the present invention.

The above embodiment illustrates a method of adjusting an operation mode of an audio / video receiver and a digital audio storage medium by using an associated service bit.

Referring to FIG. 6, operation modes of the audio / video receiver and the digital audio storage medium proposed by the present invention when the IEC958 multiple streams are input are as follows.

The method can be divided into three types.

The first is the main audio service mode. This mode decodes or stores only the main audio service among a total of eight bitstreams. If the audio / video receiver can only handle a single stream, it can, by default, handle the data stream number '0', and the user can select the main audio service from one of the bitstream numbers '0' to '7'. Can be. If multiple stream decoding is possible, the user can select as many streams as possible. In case of storing in the digital audio storage medium, the related audio service is discarded and only the main audio service is stored.

The second is the main and associated audio service mode.

This mode decodes or stores both the main audio service and the related audio service among a total of eight bitstreams. If the audio / video receiver can only process a single stream, the bitstream number is '0' by default and only one of the bitstream numbers '0' to '7' can be selected by the user. If multiple stream decoding is possible, all bitstreams are output by sequentially decoding the main audio stream and related audio services. When storing in the digital audio storage medium, all the received main audio services and related audio services are stored.

The last is the associated audio service mode.

This mode decodes or stores only related audio services among a total of eight bitstreams. If the audio / video receiver can only handle a single stream, the data stream number is '0' by default, and the user can select only one related audio service from '0' to '7' data stream numbers. . If multiple stream decoding is possible, the user can select as many streams as possible. When storing in a digital audio storage medium, the main audio service is discarded and only the related audio service is stored.

As described above, it has been described with reference to the preferred embodiment of the present invention, but those skilled in the art various modifications and changes of the present invention without departing from the spirit and scope of the present invention described in the claims below I can understand that you can.

As described above, according to the present invention, since the main audio service and the related audio service can be distinguished, the user can selectively decode or store a desired service or a stream of a specific bitstream number.

1 is a block diagram of an audio stream coded with AC-3.

2 shows the structure of a bit stream information field.

3 is a table showing a bit stream mode.

4 is a structure of AC-3 data-burst.

Fig. 5 shows the structure of Pc in the header of the data-burst of AC-3.

FIG. 6 illustrates a structure in which an associated service bit is applied to Pc in a header of a data burst of AC-3 according to an embodiment of the present invention.

7 illustrates a method of transmitting data and a method of decoding and storing an audio video receiver according to an embodiment of the present invention.

Claims (13)

a) IEC-958 including at least one of main audio data or related audio data divided by using a predetermined bit value in a field indicating information on AC-3 data among headers included in an AC-3 data burst; Receiving AC-3 audio data decoded in SPDIF format; b) determining a predetermined mode for processing the decoded AC-3 audio data; and c) a method of decoding the main audio source and the related audio source transmitted to IC958, comprising the step of processing data according to the corresponding mode selected in step b).  The method according to claim 1, wherein the predetermined part of the bits in the field representing the information on the AC-3 data of step a) is a storage area bit. The method of claim 2, wherein the method for classifying the AC-3 data by using a predetermined bit value in the field indicating information on AC-3 data includes a value of 0 when the storage area bit is main audio data, and a case of related audio data. The decoding method of the main audio source and the associated audio source transmitted to IC958, characterized in that to store by distinguishing the value of 1 4. The method according to any one of claims 1 to 3, wherein the predetermined mode of step b) is A method of decoding a main audio source and an associated audio source transmitted to IC958, comprising a main audio service mode and a main and related audio service modes and an associated audio service mode. 5. The method of claim 4, wherein the main audio service is selected in step b). In step c), if the audio and video receiver can decode only a single stream, the audio video receiver processes a data stream number of 0 by default, and allows one of the main audio services from 0 to 7 to be selected. Decoding method of main audio source and related audio source transmitted to IC958 5. The method of claim 4, wherein the main audio service is selected in step b). The method of decoding the main audio source and the associated audio source transmitted to IC958, characterized in that in step c) the audio-video receiver allows the user to select as many streams as possible if multiple stream decoding is possible. 5. The method of claim 4, wherein the main audio service is selected in step b). If the data is stored in the digital audio storage medium in step c), only the main audio service is stored. 5. The method of claim 4, wherein in step b) the main and associated audio services are selected. IC958, characterized in that step c) if the audio and video receiver is capable of decoding only a single stream, by default treats the data stream number as 0 and allows the audio service of only one of the data stream numbers from 0 to 7 to be selected. To decode the main audio source and its associated audio source 5. The method of claim 4, wherein in step b) the main and associated audio services are selected. Step c) is a method of decoding the main audio source and the associated audio source transmitted to IC958, characterized in that if the audio video receiver is capable of multi-stream decoding, sequentially decoding the main audio stream and the associated audio service. 5. The method of claim 4, wherein in step b) the main and associated audio services are selected. A method of decoding the main audio source and the related audio source transmitted to IC958, characterized in that if step c) stores data on the digital audio storage medium, all input main audio services and related audio services are stored. 5. The method of claim 4, wherein in step b) an associated audio service is selected. IC958, characterized in that step c), if the audio and video receiver is capable of decoding only a single stream, by default handles the data stream number being zero and allows the selection of an associated audio service from one of the data stream numbers from zero to seven. To decode the main audio source and its associated audio source 5. The method of claim 4, wherein in step b) an associated audio service is selected. Step c) is a method of decoding a main audio source and an associated audio source transmitted to IC958, characterized in that the audio video receiver allows the user to select as many streams as possible if multiple stream decoding is possible. 5. The method of claim 4, wherein in step b) an associated audio service is selected. A method for decoding the main audio source and the related audio source transmitted to IC958, characterized in that only the relevant audio service is stored if step c) stores the data on the digital audio storage medium.