JP4556785B2 - Data transmission system - Google Patents

Description

The present invention relates to a data transmission system for transmitting stream data, for example, in BS · CS digital broadcasting and terrestrial digital broadcasting.

  In digital broadcasting and terrestrial digital broadcasting of BS (Broadcasting Satellite) and CS (Communication Satellite), one or a plurality of video data and audio data, digital data for data broadcasting, and the like are packetized and multiplexed. Broadcast data is transmitted by generating stream data for transmission (for example, a transport stream in the MPEG-2 format: hereinafter referred to as TS) and wirelessly transmitting the TS according to a predetermined communication method. In addition, a plurality of TSs are remultiplexed, and data of a plurality of programs are collectively transmitted to one TS and wirelessly transmitted.

  In such digital broadcasting, processing for adjusting the data length of the TS to a specified value is performed in order to wirelessly transmit the TS in accordance with a predetermined communication method. For example, in BS / CS digital broadcasting, when a plurality of TSs having different modulation schemes are combined, a null is generated in conjunction with TMCC (Transmission and Multiplexing Configuration Control) transmission timing in order to artificially synchronize the plurality of TSs. A process of inserting a packet and holding the time reference of each TS is performed.

  Also, in terrestrial digital broadcasting, when TS is modulated by OFDM (Orthogonal Wave Frequency Division Multiplexing), the OFDM frame is configured by matching so that the packet unit can be allocated to each layer of the OFDM signal. By inserting a null packet into the TS, the TS transmission clock is fixed, and it is possible to share the sample clock used for demodulating the OFDM signal by FFT (Fast Fourier Transform) and the TS transmission clock.

In addition, as a conventional technique related to the present invention, Patent Document 1 discloses that a time stamp value of a specific packet is recorded in a payload of a null packet in order to transmit video data and audio data via an IEEE1394 interface. Thus, a technique is disclosed in which reproduction of stream data can be started from many positions.
Japanese Patent Application No. 2002-81003 (pages 19-20)

  In the above-described digital broadcasting, null packets are inserted at various locations in the TS as described above, and accordingly, a broadcast signal of a data packet in which no actual data is inserted is transmitted, and radio waves are wasted.

  In digital broadcasting, data broadcasting in which various kinds of digital data such as character information and image information are transmitted in parallel with video content is carried out. In data broadcasting, a large number of packets are connected to restore one data. In addition to the configuration, the display form must follow a predetermined complicated method, and therefore, the processing load for displaying the data broadcast is large, and the time lag from operation to display is generally large.

It is an object of the present invention to be able to be used by processing with a light load while eliminating waste of signal transmission that does not contain actual data due to null packet insertion in digital broadcasting, and can be further improved in user convenience information, to provide a data transmission system capable of transmitting together with the digital broadcasting.

In order to achieve the above object, the present invention provides a stream generation means for packetizing and multiplexing a plurality of transmission data including video data and audio data to generate one stream data, and continuously transmitting the stream data. In a data transmission system comprising: a transmission device comprising a transmission means; and a reception device that receives the stream data and demodulates the transmission data, the transmission device accumulates additional information and packetizes the additional information Processing means, wherein the stream generation means is configured to add the additional data when a data amount for a predetermined time of the plurality of transmission data is less than a predetermined value in order to adjust a data length for the predetermined time of the stream data to a predetermined value. The additional information packet packetized by the information processing means is multiplexed in addition to the plurality of transmission data. The stream data is configured to be generated, and the additional information packet is provided with the same packet identification information as that of a null packet, and the reception device receives the same packet identification information as that of the null packet among the data packets of the stream data. Means for separating the data packet, and additional information analyzing means for analyzing the data packet and converting the additional information into display data when the additional information is included in the data packet and outputting the display data to the display processing unit The additional information analysis means discards the additional information packet supplied up to the present time at regular intervals and stops outputting display data based on the additional information of the additional information packet to the display processing unit. Then, the additional information packet to be supplied next is processed.

  According to such means, since the additional information packet is inserted instead of the conventional null packet, the transmission of the null signal, which is the transmission of the null packet, is eliminated and the user's convenience is improved. Possible additional information can be transmitted.

In addition, since the additional information packet has the same packet identification information as that of the null packet , the additional information packet can be handled and inserted into the TS in the same manner as the null packet. The additional information can be extracted by using the packet identification information as an index and further identifying the packet as a null packet by looking at the packet contents.

Further preferably, the biasing pressure information, may be the data structure to be completed only by one packet.

  With such a configuration, it is not necessary to perform processing for restoring one piece of data by combining a large number of packet data, such as data broadcasting, on the receiving side, and no additional load is imposed on the use of additional information. It is possible to perform a short period of time from receiving the message to executing the function using the additional information.

  As described above, according to the present invention, it is possible to use in processing that does not require a large load while eliminating wasteful signal transmission due to conventional null packet insertion, and improving user convenience. There is an effect that transmission of additional information that can contribute can be realized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIGS. 1 and 2 are configuration diagrams of a transmission device and a reception device, respectively, of a digital broadcast transmission system according to an embodiment of the present invention.

  The transmission system of this embodiment shows an example in which the present invention is applied to terrestrial digital broadcasting. In the terrestrial digital broadcasting, a transmission apparatus 10 that transmits broadcasting radio waves for one channel and the terrestrial digital broadcasting are received and broadcasted. It is comprised from the receiver 40 which reproduces | regenerates a program.

  The transmission apparatus 10 includes a plurality of sets of information source encoding units 11 for digitizing and compressing broadcast video / audio / data, and multiplexing and encoding of the encoded digital data of the video / audio / data. These are formed by a plurality of sets of multiplexing units & limited reception processing units 12 that perform limited reception processing for pay broadcasting, and a plurality of sets of information source encoding units 11... And multiplexing units & limited reception processing units 12. A TS remultiplexing unit 13 that remultiplexes a plurality of TSs to generate one transmission TS, a transmission line encoding unit 14 that performs encoding processing for radio transmission on the transmission TS, and An IFFT circuit 15 that performs an IFFT (Inverse Fast Fourier Transform) process on the signal processed by the transmission path encoding unit 14 to form an OFDM transmission wave, and an additional information processing unit (additional information) that performs processing related to the additional information And a processing unit) 16.

  The additional information processing unit 16 receives and accumulates additional data from the outside, converts it into TS packet data (hereinafter referred to as additional information packet), and responds to the request from the TS remultiplexing unit 13 The additional information packet is supplied to the TS remultiplexing unit 13.

  The TS re-multiplexing unit 13 re-multiplexes a plurality of TSs supplied from a plurality of sets of multiplexing units & conditional access processing units 12... By reordering packets suitable for hierarchical transmission of OFDM signals. Program arrangement information (SI: Service Information) for generating a program guide, program specification information (PSI: Program Specific Information) indicating a program combination method, and the like are packetized and multiplexed into a TS.

  The TS remultiplexing unit 13 multiplexes the additional information packet supplied from the additional information processing unit 16 in place of the null packet at the timing when the null packet is inserted in order to fix the transmission clock of the conventional TS. It is configured to become. Further, when there is no accumulation of additional information, a null packet is inserted as in the prior art. Although details will be described later, the additional information packet has the same packet ID (packet identification information) as that of the null packet, and the transmission path encoding unit 14 performs the same processing as when the null packet is inserted. .

  The receiving device 40 includes a network interface module (NIM) 41 that performs channel selection, TS demodulation, and the like, a Demux 42 that separates and outputs video data and audio data from the TS output from the NIM 41, and video data that is output separately. A video decoder 43 that outputs a video signal by combining the audio data, an audio decoder 44 that outputs the audio signal by combining the separated audio data, and additional information analysis means for analyzing an additional information packet included in the demodulated data And an additional information processing unit 45, a display processing unit 46 for synthesizing the video signal from the video decoder 43 and the display signal of the additional information.

  Although not shown, the receiving device 40 controls the NIM 41 and the display processing unit 46 in response to an input from an operation input unit (such as an operation panel or a remote control) for inputting an operation from the user or an operation input unit. A control circuit or the like is provided to change the selected channel or selected TS of the NIM 41 or to turn on / off the display of additional information by a user operation input.

  The NIM 41 extracts the signal of the frequency of the selected channel from the radio wave received from the antenna ANT, restores the TS sent from the broadcasting station by performing demodulation processing, error correction processing, etc. on the signal of this frequency, and One MPEG2 format TS multiplexed and synthesized with this TS is separated and output based on the packet ID.

  In addition, the NIM 41 of this embodiment, when separating one TS from a TS in which a plurality of TSs are multiplexed, when there is a data packet having a null packet ID “0x1FFF”, The data packet is separated and output to the additional information processing unit 45.

  When the data packet is supplied from the NIM 41, the additional information processing unit 45 analyzes the data, and when the additional information is included in the data packet, converts the additional information into display data and outputs the display data to the display processing unit. It is configured as follows. Although the additional information packet including the additional information is supplied irregularly, the additional information processing unit 45 discards the additional information packet supplied up to the present time at regular intervals, for example, and supplies the additional information supplied next. By performing the packet processing, it is possible to switch the display of the additional information supplied irregularly at an appropriate timing. Alternatively, each time a new additional information packet is supplied, the previously supplied additional information packet may be discarded and the display control process for the new additional information packet may be performed.

  The display processing unit superimposes the display data signal sent from the additional information processing unit 45 on the video signal by, for example, OSD (On Screen Display) processing when the additional information display ON operation input is made. In this way, display output is performed in which additional information is superimposed on the video display by character display or the like.

  Next, the data structure of the additional information packet will be described.

  FIG. 3 is a data chart showing the data structure of the additional information packet, and FIGS. 4 to 6 are tables showing specific examples of codes input to predetermined fields of the additional information packet and their contents.

  As shown in FIG. 3, the additional information packet is composed of a 4-byte packet header and a 184-byte payload portion, as in a normal TS packet. The value of the packet header is “0x1FFF”, which is the same as the null packet, and additional information is written in the payload portion.

  The additional information written in the payload portion has a hierarchical data structure, and the information content is described by a 4-byte information type field in which codes representing information classification are registered, and text data or image data, for example. The data field is divided into 180 bytes.

  Further, the information type field is divided into a 1-byte type field in which a code indicating an information type is registered and a 3-byte classification field in which a code indicating a classification of information is registered. In the type field, for example, as shown in FIG. 4, a value “0x1” indicating that it is broadcast program category information, a value “0x2” indicating commercial, and weather information are indicated. Codes representing various information types determined in advance, such as a value “0x3” and a value “0x4” indicating information related to the season such as a flowering pattern, are registered.

  Furthermore, the hierarchical structure of the classification field is defined according to the value of the type field. For example, when the code of the type field is a value of “program category”, the large classification field of 1 byte and the middle classification of 1 byte are used. It is divided into a field and a 1-byte spare field. For example, a code representing one category when a broadcast program is largely classified as shown in FIG. 5 is displayed in the large classification field, and one code when a large classification category is further finely classified in the middle classification field. Each category code is registered.

  The classification field is divided into a 1-byte major classification field, a 6-bit middle classification field, and a 10-bit minor classification field when the code of the classification field is a value of “weather information”. For example, as shown in FIG. 6, a code representing a country name is registered in the large classification field, a code representing a wide area name is registered in the middle classification field, and a code representing a small area name is registered in the small classification field. It has come to be.

  The format of the 180-byte data field is also defined by the value of the type field. For example, when the code of the type field is the value of “program category”, the data field is not used, and the code of the type field is “ In the case of the value of “weather information”, only the upper 19 bytes are used, and data representing the contents of the weather is written there by text data or the like.

  Such an additional information packet is transmitted from the transmission device 10 to the reception device 40 in parallel with the transmission of the program broadcast as described above.

  As described above, according to the digital broadcast transmission system and transmission method of this embodiment, the conventional case where the null packet is inserted into the TS is replaced with the additional information packet having the packet ID of the null packet. Therefore, it is possible to transmit the additional information that can contribute to the improvement of the convenience for the user while eliminating the waste of signal transmission without content due to the insertion of the null packet.

  Further, since the additional information is completed as one data in one packet, unlike the data broadcasting in which a series of data is restored by connecting a plurality of packets, the reproduction processing can be performed with a small load. Can be made cheaper.

  Further, since the additional information has an information type field in which the information classification of the additional information is represented by a predetermined code, a wide variety of additional information can be transmitted with a small amount of data.

  The present invention is not limited to the above-described embodiment, and various modifications can be made. For example, in the above-described embodiment, an example in which the present invention is applied to a terrestrial digital broadcast transmission system is shown, but the present invention can be similarly applied to a BS or CS digital broadcast transmission system. In other words, an additional information packet may be inserted instead of a null packet that has been inserted at the time of conventional TS synthesis.

  In the above embodiment, as an example of how to use additional information on the receiving device side, an example in which additional information is displayed and output superimposed on video output has been shown. However, the present invention does not limit this method of use. For example, in the case of additional information indicating a program category, operation control on the receiving device side is performed such that recording processing is automatically performed when a favorite program category registered by the user matches the program category of the additional information. It can also be used.

  In the above embodiment, the additional information is exemplified as data that is completed with one additional information packet. However, as data that restores one additional information by connecting two to five packets. Also good. The details shown in the embodiment, such as the specific contents of each code registered in the information type field of the additional information, can be appropriately changed without departing from the gist of the invention.

It is a block diagram which shows the structure of the transmitter of the digital broadcast transmission system of embodiment of this invention. It is a block diagram which shows the structure of the receiver of the digital broadcast transmission system of embodiment of this invention. It is a chart which shows the data structure of the additional information packet inserted in TS as a substitute of a null packet. It is the table | surface which showed the specific example of the code registered into the information type field in an additional information packet, and its content. It is the table | surface which showed the 1st specific example of the code registered into the information type field in an additional information packet, and its content. It is the table | surface which showed the 2nd specific example of the code registered into the information type field in an additional information packet, and its content.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Transmitting device 11 Information source encoding unit 12 Multiplexing unit & conditional reception processing unit 13 TS remultiplexing unit 14 Transmission path encoding unit 15 IFFT circuit 16 Additional information processing unit 40 Receiving device 41 NIM
42 Demux
43 Video Decoder 44 Audio Decoder 45 Additional Information Processing Unit 46 Display Processing Unit

Claims (2)

A transmission apparatus comprising: stream generation means for packetizing and multiplexing a plurality of transmission data including video data and audio data to generate one stream data; and transmission means for continuously transmitting the stream data; In a data transmission system comprising: a receiving device that receives stream data and demodulates the transmission data;
The transmitter is
Additional information processing means for accumulating additional information and packetizing it,
When the data amount for the predetermined time of the plurality of transmission data is less than a predetermined value in order to adjust the data length for the predetermined time of the stream data to a predetermined value, the stream generation unit performs packet transmission by the additional information processing unit. The streamed additional information packet is generated in addition to the plurality of transmission data and multiplexed to generate the stream data,
The additional information packet is given the same packet identification information as the null packet,
The receiving device is:
Means for separating a data packet having the same packet identification information as a null packet among data packets of the stream data;
Analyzing the data packet, and when the additional information is included in the data packet, the additional information analysis means for converting the additional information into display data and outputting to the display processing unit,
The additional information analyzing unit discards the additional information packet supplied up to the present time at regular intervals, stops outputting the display data based on the additional information of the additional information packet to the display processing unit, and supplies the display data next A data transmission system characterized in that the additional information packet is processed. The data transmission system according to claim 1 , wherein the additional information has a data configuration that is completed with only one packet.

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