JP2004056214A - Transmission apparatus for digital broadcast data - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission apparatus for digital broadcast data for converting first digital broadcast data on a first network into second digital broadcast data and transmitting the converted data onto a second network that can replace a NIT (Network Information Table) even when a data quantity of a second digital broadcast NIT of a replacement destination is greater than a data quantity of a NIT for a first digital broadcast of a replacement source. <P>SOLUTION: The transmission apparatus replaces part of a TS packet 2 incapable of replacing a TS packet 1 by using NULL packets detected from TS packets received from transmitted packets. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a digital broadcast data transmission apparatus used to edit a digital broadcast program distributed on a certain network and distribute it on another network.
[0002]
[Prior art]
2. Description of the Related Art There is a service in which a cable television company distributes a digital broadcast program such as a satellite digital broadcast using an in-house network.
Digital broadcast program data is compression-encoded by the MPEG2 system. When transmitting the program data, the program data is packetized for each block, and the resulting packet sequence is transmitted. This packet is called a TS (Transport Stream) packet, and a packet sequence formed of the TS packets is called a transport stream.
[0003]
In a series of TS packets obtained by encoding one program, only one program can be transmitted. In order to provide a plurality of programs at the same time, TS packets obtained from each program are combined into one transport stream by time division multiplexing and transmitted.
FIG. 8 shows the structure of a general TS packet. The TS packet has a fixed length of 188 bytes. The first 4 bytes constitute a header portion, and the remaining 184 bytes constitute a data portion.
[0004]
A PID (Packet Identifier) in the header is an identifier indicating the content of data stored in the packet.
The data section mainly stores the following four types of data.
(1) ES (Elementary Stream) video data and audio data (2) PSI (Program Specific Information) Additional information related to transmission control (3) SI (Service Information) Additional information related to program provision (4) Null data No space. In order to maintain a continuous transmission operation, a NULL packet is transmitted when there is no data to be transmitted.
[0005]
The PSI includes an NIT (Network Information Table). The NIT is a table including physical information about the transmission path, such as the frequency of the transmission carrier and the modulation method (for the configuration, see Japanese Patent Application Laid-Open No. 11-150717).
FIG. 9 shows a relationship between NIT data and TS packets. A series of NIT data is divided into a plurality of parts, each of which is provided with a TP header to form a TS packet. These TS packets are not always transmitted without a time gap. Often, other types of TS packets are inserted between the TS packets. Further, once NIT data is transmitted by these TS packets, the same NIT data is transmitted by the same TS packet at a fixed NIT cycle. That is, NIT data is repeatedly transmitted at a constant NIT cycle (for example, 10 seconds). Hereinafter, the number of NIT packets in one NIT cycle may be omitted and simply referred to as “the number of packets”.
[0006]
A TS packet including the head of the NIT data is referred to as a “head packet”. In some cases, the NIT data does not start from the beginning of the data portion of the first TS packet. In this case, a pointer indicating the start position of the NIT is entered in the data portion. Further, even if the last division unit of the NIT is put in the data part, the data part may remain, but in this case, zero data (0xff) is filled to the end.
Among the TS packets including the NIT data, the first TS packet and the other TS packets are distinguished by checking whether the “payload start unit indicator” in the TP header is 1 or 0 as shown in FIG. Do.
[0007]
[Problems to be solved by the invention]
In digital satellite broadcasting, NIT of original digital broadcasting data is called NIT1, and NIT of digital broadcasting data suitable for a secondary distribution network is called NIT2.
In a service in which a cable television company or the like distributes digital broadcast data using an in-house network, a conventional technique uses a TS packet including a satellite broadcast NIT and a CATV NIT of the same number of packets. It is replaced by a TS packet that includes For this reason, if the size of the CATV NIT to be replaced is larger than the original NIT size (such as occurs when a cable television company adds a unique program), replacement becomes impossible.
[0008]
Also, there is an NIT cycle for sending one NIT data. In the conventional technique, the CATV NIT can be output only in the same NIT cycle as the satellite broadcast NIT.
Therefore, the present invention provides a digital broadcast capable of performing NIT replacement even when the data amount of the replacement second digital broadcast NIT is larger than the data amount of the replacement first digital broadcast NIT. It is intended to realize a data transmission device.
[0009]
Another object of the present invention is to realize a digital broadcast data transmission apparatus capable of freely changing the output NIT cycle of the second digital broadcast NIT to a NIT cycle suitable for the second network.
[0010]
[Means for Solving the Problems]
(1) A digital broadcast data transmission apparatus according to the present invention includes: an extraction unit that extracts a TS packet including an NIT from TS packets input from a first network; , A first packet extracting means for extracting a first packet including the first data of the NIT, a converting means for converting a TS packet including the first digital broadcasting NIT into a second digital broadcasting according to the conversion information, and a first network. If the detecting means for detecting a NULL packet and the extracting means extract the first packet containing the NIT from the TS packets input from the PDU, the replacement is started from this first packet, and then the extracting means extracts the first packet. For the packet containing the NIT and the NULL packet detected by the detecting means, In which and a NIT replacement section going replacing the digital broadcasting NIT (claim 1).
[0011]
According to the above configuration, the number of packets of the TS packet including the second digital broadcasting NIT (hereinafter, referred to as “TS packet 2”) becomes smaller than the number of the TS packets including the first digital broadcasting NIT (hereinafter, “TS packet 2”). When the number of packets is larger than the number of packets ("packet 1"), the portion of TS packet 2 in which TS packet 1 cannot be replaced can be replaced using a NULL packet detected from input TS packets.
[0012]
Therefore, even if the data amount of the second digital broadcasting NIT is larger than the data amount of the first digital broadcasting NIT, the NIT can be replaced.
In the transmission apparatus for digital broadcast data, a counting means for counting the number of TS packets including the first digital broadcast NIT, the number of NULL packets, and the number of TS packets including the second digital broadcast NIT is provided. In addition,
(Number of TS packets including the first digital broadcast NIT)
+ (Number of NULL packets)
<(The number of TS packets including the second digital broadcasting NIT)
In the case where it is determined that the NIT is N, the NIT replacement means may ignore the next first packet and continue the replacement.
[0013]
Thus, even if the data of the second digital broadcasting NIT is extremely increased compared to the data of the first digital broadcasting NIT (when the inequality in the above expression is satisfied), the NIT can be replaced. However, the NIT cycle for transmitting the second digital broadcast NIT cannot be synchronized with the NIT cycle for transmitting the first digital broadcast NIT.
When the inequality sign in the above equation is not satisfied (in the case of ≧), the replacement can always be started from the first packet extracted by the extracting means, so that the NIT cycle for transmitting the second digital broadcasting NIT is set to , Can be synchronized with the NIT cycle for transmitting the first digital broadcast NIT.
[0014]
(2) The digital broadcast data transmission device of the present invention includes an extraction unit for extracting a TS packet including an NIT from among TS packets input from the first network, and a first digital broadcast NIT. Conversion means for converting the TS packet for the second digital broadcast according to the conversion information, detection means for detecting a NULL packet from the TS packets input from the first network, and NIT extracted by the extraction means NULL replacing means for replacing included packets with NULL packets, and NIT replacing means for replacing the NULL packet detected by the detecting means and the NULL packet replaced by the NULL replacing means with the second digital broadcasting NIT. (Claim 3).
[0015]
According to the present invention, a TS packet containing a NIT and a NULL packet are extracted from TS packets input from the first network, all of them are replaced with NULL packets, and these NULL packets are , The second digital broadcasting NIT is replaced.
The NIT cycle of the second digital broadcast NIT can be set independently of the NIT cycle of the first digital broadcast NIT. Therefore, the output NIT cycle of the second digital broadcasting NIT can be freely changed to a NIT cycle suitable for the second network.
[0016]
In the above configuration, the TS packet containing the NIT and the NULL packet are extracted from the TS packets input from the first network, and all of them are replaced with the NULL packet. Instead, the second digital broadcast NIT may be directly replaced with the packet containing the NIT extracted by the extraction means and the NULL packet detected by the detection means (claim 4).
[0017]
A TS packet containing the second digital broadcast NIT converted by the conversion means is stored in a memory, and the NIT replacement means reads this memory at an output NIT cycle of the second digital broadcast NIT. The packet may be replaced with a packet including the second digital broadcast NIT (claim 5).
By providing such a memory, the output of the second digital broadcast NIT can be maintained even when the transmission of the first digital broadcast NIT is stopped due to a broadcast accident or the like.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention in the case where a digital broadcast signal for CATV is generated and transmitted by changing the transmission frequency, the modulation method, and the like of the digital broadcast signal transmitted from the transponder of the communication satellite will be described. This will be described in detail with reference to the drawings.
-First embodiment-
FIG. 1 is a schematic configuration diagram of a digital broadcast data transmission device 1 according to a first embodiment of the present invention.
[0019]
The transmission apparatus 1 replaces a packet containing an NIT (hereinafter, referred to as a “NIT packet”) with a NIT packet for CATV, among TS packets 1 of the MPEG2 standard sequentially obtained from a decoder for demodulating a satellite digital broadcast signal. It has a replacement unit 2.
Further, the transmission device 1 adapts the NIT packet extraction circuit 3 for extracting the NIT packet from the TS packets 1 obtained sequentially, the NIT buffer 4 for storing the extracted NIT, and the NIT for CATV broadcasting according to the conversion information. And a CATV NIT conversion unit 5 for performing the conversion as described above. The CATV NIT conversion unit 5 notifies the control unit 7 of information on the number of CATV NIT packets (in one NIT cycle).
[0020]
When the NIT packet extraction circuit 3 extracts the NIT packet, it notifies the NIT replacement unit 2 of the extraction (NIT packet notification).
When the first NIT packet is extracted, the NIT packet extraction circuit 3 notifies the control unit 7 of the extraction.
Further, the transmission device 1 includes a NULL packet detection circuit 6 that detects a packet including NULL (referred to as “NULL packet”). When detecting a NULL packet, the NULL packet detection circuit 6 notifies the NIT replacement unit 2 of the detection (NULL notification).
[0021]
Further, the transmission device 1 includes a satellite broadcast NIT / NULL packet counter 8 that counts packets that can be replaced with CATV NIT packets based on the NULL notification and the NIT packet notification.
Further, the transmission device 1 has a control unit 7. The control unit 7 receives the NIT packet from the NIT packet extraction circuit 3 after the time when the packet count value of the satellite broadcast NIT / NULL packet counter 8 exceeds the number of CATV NIT packets notified from the CATV NIT conversion unit 5. When the head packet notification is input, the NIT head packet notification is output to the NIT replacement unit 2 as it is. When the control unit 7 outputs the NIT head packet notification to the NIT replacement unit 2, the control unit 7 resets the count value of the satellite broadcast NIT / NULL packet counter 8.
[0022]
When the packet count value of the satellite broadcast NIT / NULL packet counter 8 does not exceed the CATV NIT packet number notified from the CATV NIT conversion unit 5, the control unit 7 sends the NIT packet from the NIT packet extraction circuit 3 to the NIT packet extraction circuit 3. When the packet notification is input, the NIT replacement unit 2 does not output the NIT head packet notification but outputs 0.
The NIT replacement unit 2, for the NIT packet and the NULL packet in the TS packet 1 obtained sequentially, receives the NIT head packet notification and, at the time of receiving the NIT head packet notification, converts the head of the CATV NIT conversion unit 5 It is replaced sequentially from the packet.
[0023]
All or some of the functions of the units 2, 5, and 7 are realized by a computer of the transmission device 1 executing a program recorded on a predetermined medium such as a CD-ROM or a hard disk.
Hereinafter, the operation of the transmission device 1 will be described.
<Operation 1.1 (when the number of packets of the CATV NIT is smaller than that of the satellite broadcast NIT)>
FIG. 2 is a sequence diagram for explaining the NIT packet replacement operation when the number of packets in one NIT cycle is smaller in the CATV NIT than in the satellite broadcast NIT. The upper part (a) shows a sequence of TS packets input from a satellite, and the lower part (b) shows a sequence of TS packets output to CATV.
[0024]
The NIT replacement unit 2 starts replacing the head packet of the satellite broadcast NIT with the head packet of the CATV NIT. The surplus satellite broadcast NIT packet is replaced with a NULL packet and output.
<Operation 1.2 (when the CATV NIT has a larger number of packets than the satellite broadcast NIT)>
FIG. 3 is a sequence diagram for explaining the NIT replacement operation when the CATV NIT has a larger number of packets than the satellite broadcast NIT. The upper part (a) shows a sequence of TS packets input from a satellite, and the lower part (b) shows a sequence of TS packets output to CATV.
[0025]
The NIT replacement unit 2 starts replacing the head packet of the satellite broadcast NIT with the head packet of the CATV NIT. The NULL packet included in the input TS packet sequence from the satellite is replaced with a CATV NIT packet and output.
<Operation 1.3 (when the number of packets in the CATV NIT is extremely larger than that in the satellite broadcast NIT)>
FIG. 4 is a sequence diagram for explaining the NIT replacement operation when the data amount of the CATV NIT is extremely larger than that of the satellite broadcast NIT. The upper part (a) shows a sequence of TS packets input from a satellite, and the lower part (b) shows a sequence of TS packets output to CATV.
[0026]
The NIT replacement unit 2 starts replacing the head packet of the satellite broadcast NIT with the head packet of the CATV NIT. The NULL packet included in the input TS packet sequence from the satellite is also replaced with the CATV NIT packet.
However, even if NIT packets for satellite broadcasting for one NIT cycle are input from the head and all are replaced with CATV NIT packets, if the CATV NIT remains, even if the next packet of satellite broadcasting NIT comes, , Ignoring the first packet, and replacing the remaining packets with the CATV NIT packet. Thereafter, when all of the packets are replaced with the CATV NIT packets, the first packet of the next satellite broadcast NIT is awaited.
[0027]
Therefore, one or more NIT cycles of the satellite broadcast NIT are skipped.
-Second Embodiment-
FIG. 5 is a schematic configuration diagram of a digital broadcast data transmission device 1 according to the second embodiment of the present invention.
The transmission apparatus 1 includes a NIT packet extracting circuit 3 for extracting NIT packets from TS packets sequentially obtained by a decoder, an NIT buffer 4 for storing the extracted NITs, and converting NITs suitable for CATV broadcasting according to conversion information. It has a CATV NIT conversion unit 5, a NULL packet detection circuit 6, and a NIT replacement unit 2.
[0028]
Further, the transmission device 1 has a NULL replacement circuit 11 for replacing a NIT packet in an input TS packet with a NULL packet.
Further, the transmission device 1 includes a NIT cycle detection circuit 12, a control unit 13, a switching circuit 14, and a memory 15.
The NIT cycle detection circuit 12 detects a NIT cycle based on NIT packets sequentially obtained from a decoder for demodulating a satellite digital broadcast signal.
[0029]
The switching circuit 14 switches between setting the cycle of the CATV NIT to be output to a cycle unique to CATV or a cycle of a satellite digital broadcast signal.
The control unit 13 sets the timing of replacing the satellite NIT packet with the CATV NIT packet based on the set NIT cycle.
The memory 15 stores the CATV NIT packet converted by the CATV NIT conversion unit 5. As will be described later, the CATV NIT packet can be output at a period independent of the period of the satellite NIT packet. Therefore, even if the input of the satellite NIT packet is stopped due to some failure, the CATV NIT packet is output. Yes, CATV broadcasting can be continued.
[0030]
<Operation 2.1 (when the data amount of the CATV NIT is smaller than that of the satellite broadcast NIT)>
FIG. 6 is a sequence diagram for explaining an operation of rewriting all satellite broadcast NIT packets into NULL packets and then writing the contents of the CATV NIT packets. The upper part (a) shows a TS packet sequence input from a satellite, and the middle part (b) shows a TS packet sequence output from the NULL replacement circuit 11 in which all NIT packets are overwritten with NULL packets. Indicates an output TS packet sequence to CATV.
[0031]
When the NIT packet extraction circuit 3 extracts the NIT packet from the input TS packets, it notifies the NULL replacement circuit of the extraction. The NULL replacement circuit overwrites the NIT packet with a NULL packet.
The overwritten NULL packet and the original NULL packet are detected by the NULL packet detection circuit 6, and when the NULL packet detection circuit 6 detects the NULL packet, the NULL packet detection circuit 6 notifies the NIT replacement unit 2 of the detection.
[0032]
On the other hand, the control unit 13 inputs a trigger signal to the NIT replacement unit 2 at a cycle according to the setting of the switching circuit 14. For example, when a cycle unique to CATV is set, a trigger signal is input at the start timing of a NIT cycle unique to CATV.
The NIT replacement unit 2 starts replacing a NULL packet with a CATV NIT packet from the head timing of the NIT cycle.
In this way, the output cycle of the NIT suitable for the CATV network can be set arbitrarily without being particular about the NIT cycle of the original satellite broadcast network.
[0033]
The transmission device 1 according to the second embodiment described above overwrites a satellite broadcast NIT packet with a NULL packet and then replaces the satellite broadcast NIT packet with a CATV NIT packet. It can be replaced with a packet of NIT.
FIG. 7 is a configuration diagram of a transmission apparatus 1 that directly replaces such a satellite broadcast NIT packet with a CATV NIT packet. As compared with the configuration of FIG. 5, the NULL replacement circuit 11 is omitted, and the NIT packet notification signal of the NIT packet extraction circuit 3 is directly input to the NIT replacement unit 2.
[0034]
The rewriting operation is the same as that of FIG. 6 except that the middle stage (b) is omitted.
[0035]
【The invention's effect】
As described above, according to the present invention, even if the data amount of the replacement second digital broadcasting NIT is larger than the data amount of the replacement first digital broadcasting NIT, the replacement of the NIT is performed. Can be.
Further, according to the present invention, the output NIT cycle of the second digital broadcasting NIT can be freely set to a NIT cycle suitable for the second network.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a digital broadcast data transmission device 1 according to a first embodiment of the present invention.
FIG. 2 is a sequence diagram for explaining an NIT packet replacement operation when the number of packets in one NIT cycle is smaller in a CATV NIT than in a satellite broadcast NIT.
FIG. 3 is a sequence diagram for explaining an NIT replacement operation when a CATV NIT has a larger number of packets than a satellite broadcast NIT.
FIG. 4 is a sequence diagram for explaining an NIT replacement operation when the data amount of the CATV NIT is extremely larger than that of the satellite broadcast NIT.
FIG. 5 is a schematic configuration diagram of a digital broadcast data transmission device 1 according to a second embodiment of the present invention.
FIG. 6 is a sequence diagram illustrating an operation of rewriting all satellite broadcast NIT packets into NULL packets and then writing the contents of the CATV NIT packets.
FIG. 7 is a configuration diagram of a transmission apparatus 1 for directly replacing a satellite broadcast NIT packet with a CATV NIT packet.
FIG. 8 is a structural diagram of a general TS packet.
FIG. 9 is a diagram showing a relationship between NIT data and TS packets.
FIG. 10 is a detailed diagram of a TP header of a TS packet.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 transmission apparatus 2 NIT replacement section 3 NIT packet extraction circuit 4 NIT buffer 5 NIT conversion section for CATV 6 NULL packet detection circuit 7 control section 8 NIT / NULL packet counter for satellite broadcasting 11 NULL replacement circuit 12 NIT cycle detection circuit 13 control section 14 Switching circuit 15 Memory

Claims (5)

A digital broadcast data transmission device for converting first digital broadcast data on a first network into second digital broadcast data and transmitting the digital broadcast data on a second network,
The first and second digital broadcast data are each composed of a series of TS (Transport
(Stream) packet.
Among the TS packets input from the first network, there are TS packets including a first digital broadcast NIT (Network Information Table), and the TS packet including the NIT is a first packet corresponding to one NIT. And one or more TS packets including
Extracting means for extracting a TS packet including the NIT from TS packets input from the first network;
A head packet extracting means for extracting a head packet including head data of the NIT from TS packets including the NIT,
Conversion means for converting a TS packet containing the first digital broadcast NIT into a second digital broadcast according to the conversion information;
Detecting means for detecting a NULL packet from TS packets input from the first network;
When the leading packet including the NIT is extracted by the extracting means, the replacement is started from the leading packet, and subsequently, the packet including the NIT extracted by the extracting means and the NULL packet detected by the detecting means are NIT replacement means for replacing a second digital broadcast NIT. A counting unit that counts the number of TS packets including the first digital broadcasting NIT, the number of NULL packets, and the number of TS packets including the second digital broadcasting NIT;
(Number of TS packets including the first digital broadcast NIT)
+ (Number of NULL packets)
<(The number of TS packets including the second digital broadcasting NIT)
2. The digital broadcast data transmission device according to claim 1, wherein when it is determined that the NIT is NIT, the NIT replacement means ignores the next first packet and continues the replacement. An apparatus for transmitting digital broadcast data for converting first digital broadcast data on a first network into second digital broadcast data and transmitting the digital broadcast data on a second network,
The first and second digital broadcast data are each composed of a series of TS (Transport
(Stream) packet.
TS packets input from the first network include a TS packet including a first digital broadcasting NIT (Network Information Table), and the TS packet including the NIT includes a leading packet corresponding to one NIT. And one or more TS packets including
Extracting means for extracting a TS packet including the NIT from TS packets input from the first network;
Conversion means for converting a TS packet containing the first digital broadcast NIT into a second digital broadcast according to the conversion information;
Detecting means for detecting a NULL packet from TS packets input from the first network;
NULL replacing means for replacing a packet containing the NIT extracted by the extracting means with a NULL packet;
Digital broadcast data transmission apparatus, comprising: a NIT replacement means for replacing a second digital broadcast NIT with a NULL packet detected by the detection means and a NULL packet replaced by the NULL replacement means. . An apparatus for transmitting digital broadcast data for converting first digital broadcast data on a first network into second digital broadcast data and transmitting the digital broadcast data on a second network,
The first and second digital broadcast data are each transmitted by a series of TS (Transport Stream) packets,
TS packets input from the first network include a TS packet including a first digital broadcasting NIT (Network Information Table), and the TS packet including the NIT includes a leading packet corresponding to one NIT. And one or more TS packets including
Extracting means for extracting a TS packet including the NIT from TS packets input from the first network;
Conversion means for converting a TS packet containing the first digital broadcast NIT into a second digital broadcast according to the conversion information;
Detecting means for detecting a NULL packet from TS packets input from the first network;
NIT replacement means for replacing the second digital broadcast NIT with respect to the packet containing the NIT extracted by the extraction means and the NULL packet detected by the detection means. Transmission equipment. A memory for storing a TS packet containing the second digital broadcast NIT converted by the conversion means;
5. The digital broadcast data transmission apparatus according to claim 3, wherein said NIT replacement means reads said memory at a predetermined NIT cycle and replaces said memory with a packet including a second digital broadcast NIT.

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