BR112012020939B1 - TRANSMISSION APPLIANCE, RECEIVING APPLIANCE, COMMUNICATION SYSTEM, TRANSMISSION METHOD AND METHOD OF CONVERSION INTO A RECEIVING APPLIANCE - Google Patents

Abstract

TRANSMISSION APPLIANCE, RECEIVING APPLIANCE, COMMUNICATION SYSTEM, TRANSMISSION METHOD AND METHOD OF CONVERSION INTO A RECEIVING APPLIANCE. In order for a receiving apparatus to reproduce a broadcast stream without taking the frame configuration of the broadcast stream into consideration, a transmitting apparatus compresses a broadcast stream including frames to generate a data signal, each frame including broadcast packets, each transmission packet including a header unit, a data unit, and an attached information unit, and transmits the data signal using transmission packets, the transmission apparatus includes: a generation unit which compresses the broadcast stream to generate the data signal, if a Null packet which is a kind of transmission packet is present in the broadcast stream, converting a compression target portion into an indicating information unit having a size smaller than a size of the target portion of compression and which indicates that the packet is a Null packet, the target compression portion being at least part of a portion including the c unit. header and the data unit of the Null packet; and a unit (...).

Description

technical field

[0001] The present invention relates to a transmission apparatus, reception apparatus, communication system, transmission method, and conversion method for transmitting a broadcast stream.

prior technique

[0002] Techniques are known by which a TS (Transport Stream) in a signal format for digital terrestrial broadcasting is transmitted to a predetermined broadcast station or a relay station. A TS in a digital terrestrial broadcasting signal format can generally be called a broadcast stream.

[0003] An exemplary TS in a digital terrestrial broadcasting signal format is a broadcasting TS in ISDB-T (Digital Terrestrial Broadcasting Integrated Service) format. A broadcast TS includes multiplex frames in which items of information (eg, audio information, video information, and data information) are multiplexed. For a broadcast TS in ISDB-T format, multiplex frames are generated by multiplexing frames in which items of information are multiplexed. A multiplex frame includes broadcast TS packets.

[0004] Patent Document 1 describes a transmission system that converts a broadcast TS in ISDB-T format into a signal format for digital satellite transmission and transmits the broadcast TS to a relay station via a broadcast satellite and converts the received broadcast TS into ISDB-T format.

[0005] The transmission system described in Patent Document 1, to reduce the amount of transmission, eliminate Null packets in broadcasting TS in ISDB-T format. The transmission system then converts the broadcast TS in which the Null packets have been eliminated into the signal format for digital satellite transmission and transmits the converted broadcast TS.

Prior art document

[0006] Patent Document

[0007] Patent Document 1: JP2009-44354A

Invention Summary Technical problem

[0008] The transmission system described in Patent Document 1 eliminates Null packets in broadcasting TS in ISDB-T format. Broadcasting TS Drop Null packets changes the configuration of multiplex frames that included the dropped Null packets.

[0009] Therefore, in the relay station described in Patent Document 1, for example when the broadcast TS that is converted into the signal format for digital satellite transmission is converted into the broadcast TS into ISDB-T format, disadvantageously the standard of frame configuration needs to be regenerated to reconstruct the multiplex frames based on the regenerated frame configuration pattern.

[0010] The present invention is to provide a transmission apparatus, reception apparatus, communication system, transmission method, and conversion method capable of solving the above disadvantage.

Means to solve the problem

[0011] A transmission apparatus according to the invention compresses a broadcast stream including frames to generate a data signal, each frame including transmission packets, each transmission packet including a header unit, a data unit, and a information unit attached, and transmits the data signal using transmission packets, the transmission apparatus includes: generating means that compress the broadcast stream to generate the data signal, if a Null packet which is a kind of transmission packet is present in the broadcast stream, converting a compression target portion into an indicating information unit that has a size smaller than a compression target portion size and which indicates that the packet is a Null packet, the compression target portion being at least part of a portion including the header unit and the data unit of the Null packet; and transmission means that transmit the data signal using the transmission packets.

[0012] A receiving apparatus according to the invention includes: receiving means that receives the transmission packets transmitted from the transmission apparatus; acquisition means which acquires the data signal from the transmission packets received by the receiving means; and modifier means that changes the data signal in a broadcast stream, if the indicating information unit is present in the data signal acquired by the acquisition means, changing the indicating information unit at the compression target portion.

[0013] A communication system according to the invention includes the transmitting apparatus and the receiving apparatus.

[0014] A transmission method, in accordance with an exemplary aspect of the invention, in a transmission apparatus which compresses a broadcast stream including frames to generate a data signal, each frame including transmission packets, each transmission packet including a header unit, a data unit, and an attached information unit, and transmit the data signal using transmission packets, the transmission method includes: if a Null packet which is a kind of transmission packet is present in the data stream. broadcast, compresses the broadcast stream to generate the data signal by converting a compression target portion into an indicating information unit which has a size smaller than a compression target portion size and which indicates that the packet is a Null packet, the compression target portion being at least part of a portion including the header unit and the data unit of the Null packet; and transmits the data signal using the transmit packets.

[0015] A method of converting, according to the invention, in a receiving apparatus, includes: receiving the transmission packets transmitted from the transmission apparatus; acquiring the data signal from the transmission packets; and changing the step of, if the indicating information unit is present in the data signal, changing the data signal in a broadcast stream by modifying the indicating information unit in the compression target portion.

Effect of the invention

[0016] According to the present invention, it is possible to reduce the transmission amount and a receiving apparatus can reproduce a broadcast stream without regenerating the frame configuration of the broadcast stream.

Brief description of drawings

[0017] Figure 1A is a diagram showing a transmission system in an exemplary configuration;

[0018] Figure 1B is a diagram showing a TS conversion device on the transmitter side;

[0019] Fig. 1C is a diagram showing a receiver-side TS conversion device;

[0020] Fig. 2A is a diagram showing a configuration of a broadcast TS packet;

[0021] Figure 2B is a diagram showing a configuration of a transmit TS packet;

[0022] Fig. 3 is a diagram showing a broadcast TS, signal A, and signal B that are processed in the transmit side TS conversion device 12; and

[0023] Fig. 4 is a diagram showing signal B', signal A', and a broadcast TS that are processed in the receiver side TS conversion device 22.

Mode to carry out the invention

[0024] An exemplary configuration will be described below with reference to the drawings.

[0025] Figure 1A is a diagram showing an exemplary transmission system using a satellite line in accordance with the exemplary configuration of the present invention. The transmission system includes the transmission station system 1, the receiving station system 2, and the satellite apparatus 3. The transmission system may generally be called a communication system. The broadcast station system 1 can generally be called a broadcast apparatus. The receiving station system 2 can generally be called a receiving apparatus.

[0026] In Fig. 1A, the broadcast station system 1 includes the ISDB-T MUX (multiplexer) device 11, transmitter side TS conversion device 12, satellite line transmitter 13, and reference signal generator 14.

[0027] The reference signal generator 14 is a synchronous reference signal generator-GPS (Global Positioning System). The reference signal generator 14 generates 10 MHz reference signals synchronous with GPS signals and outputs the 10 MHz reference signals to the ISDB-T MUX 11 device.

[0028] The ISDB-T MUX 11 device is a multiplexing device for TSs (Transport Streams) for digital terrestrial broadcasting. The ISDB-T MUX 11 device generates a synchronous cycle with the 10 MHz reference signals that are output from the reference signal generator14. The ISDB-T MUX 11 device generates a broadcast TS of 32.5 Mbps (in a format involving a packet size of 204 bytes) synchronous with the cycle. The broadcast TS can generally be called a broadcast stream.

[0029] The broadcast TS generated by the ISDB-T MUX 11 device is a broadcast TS in ISDB-T format. A broadcast TS in ISDB-T format includes multiplex frames in which items of information (eg, audio information, video information, and data information) are multiplexed. For a broadcast TS in ISDB-T format, multiplex frames are generated by multiplexing frames in which information items are multiplexed. Multiplex frames can generally be called frames. A multiplex frame includes broadcast TS packets. Broadcast TS packets can generally be called broadcast packets.

[0030] Figure 2A is a diagram showing a broadcast TS packet configuration 4.

[0031] In Fig. 2A, the broadcast TS packet 4 includes: TS header unit 41 indicating information such as a value 0x47 (in hexadecimal representation), a packet ID (PID), and a continuity counter value ; a portion (hereinafter referred to as "payload unit") 42 including an adaptation field and a payload; and dummy byte unit 43.

[0032] The header unit of TS 41 may generally be called a header unit. The payload unit 42 can generally be called a data unit. The dummy byte unit 43 may generally be called an appended information unit.

[0033] The TS header unit 41 has a size of 4 bytes. The payload unit 42 has a size of 184 bytes. The dummy byte unit 43 has a size of 16 bytes. Therefore, broadcast TS packet 4 has a size of 204 bytes.

[0034] The first 8 bytes of the dummy byte unit 43 describe information defined according to ISDB-T. The control information is called ISDB-T information (hereafter referred to as “II”). Control information includes hierarchy information indicating a hierarchy of the broadcast TS packet 4.

[0035] The remaining eight bytes of the dummy byte unit 43 describe error correction information defined according to ISDB-T. A Reed-Solomon code (hereafter referred to as “RS”) is used as the error correction information. Hereinafter, the dummy byte unit is also referred to as an “II+RS” unit.

[0036] The ISDB-T MUX 11 device shown in figure 1A outputs the broadcast TS to the transmitter side TS conversion device 12.

[0037] When there is no data to be loaded into the payload unit 42, the ISDB-T MUX 11 device issues a packet to adjust the transmission bit rate, called a Null packet, to the side TS conversion device of transmitter 12 as a packet included in the broadcast TS, that is, as a broadcast packet.

[0038] The Null packet which is included in the broadcast TS forms part of a multiplex frame included in the broadcast TS. As with the broadcast TS packet 4, the Null packet which is included in the broadcast TS includes TS header unit 41 of a size of 4 bytes, payload unit 42 of a size of 184 bytes, and unit II +RS 43 of a size of 16 bytes.

The transmitter side TS converting device 12 receives the broadcast TS and converts the broadcast TS into a broadcast TS. The broadcast TS can generally be called a broadcast stream. Broadcast TS includes broadcast TS packets. Broadcast packets can generally be called broadcast packets.

[0040] Figure 2B is a diagram showing a transmission TS packet configuration 5.

[0041] In Fig. 2B, the transmit TS packet 5 includes: transmit TS header unit 51 indicating a value 0x47 (in hexadecimal representation) and a payload_unit_start_indicator value; and a portion (hereinafter referred to as "payload unit") 52 including an adaptation field and a payload.

[0042] The transmission header unit 51 may generally be called a header unit. The payload unit 52 may generally be called a data unit.

[0043] The transmit TS header unit 51 has a size of 4 bytes. The payload unit 52 has a size of 184 bytes. Therefore, transmission packet 5 has a size of 188 bytes.

[0044] Figure 1B is a block diagram showing the transmitter side TS conversion device 12.

[0045] In Fig. 1B, the transmitter side TS conversion device 12 includes the broadcast TS synchronizer 121, Null packet compressor 122, transmit TS packager 123, and rate conversion processor 124. The synchronizer of broadcast TS 121 and Null 122 package compressor are included in the 12A generation section. The 12A generation section can generally be called the generation medium. Transmit TS packer 123, rate conversion processor 124, and satellite line transmitter 13 are included in transmit section 12B. Transmission section 12B can generally be called transmission medium.

[0046] Figure 3 is a diagram showing the broadcast TS, signal A, and signal B that are processed in the transmitter side TS conversion device 12.

[0047] If a Null packet which is a kind of broadcast TS packet is present in the broadcast TS, the generation section 12A shown in figure 1B converts the TS header unit (4 bytes) 41 and payload unit (184 bytes) 42 in the Null packet in a tip indication byte (1 byte). The generation section 12A thus compresses the broadcast TS to generate an A signal which is a data signal. The 12A generation section outputs the A signal to the 12B transmission section.

[0048] The tip indication byte indicates a value 0xB8 representing the tip of the Null packet.

[0049] The portion including TS header unit 41 and payload unit 42 in the Null packet which is a broadcast TS packet can be called a compression target portion. The compression target portion is at least part of the portion including the TS header unit 41 and payload unit 42 in the Null packet which is a broadcast TS packet.

[0050] Transmit section 12B transmits signal A using transmit TS packets.

[0051] The broadcast TS synchronizer 121 performs synchronization detection for the broadcast TS. For example, the broadcast TS synchronizer 121 detects the value 0x47 from the TS header unit 41 in each broadcast TS packet 4. The broadcast TS synchronizer 121 generates time-synchronous synchronization signals to detect the values 0x47 and outputs the sync signals to the Null 122 packet compressor.

[0052] Null packet compressor 122 compresses Null packets in the broadcast TS (see figure 3) and generates signal A (see figure 3).

[0053] In the exemplary configuration, the Null packet compressor 122 reads information described in the TS header unit 41 of each broadcast TS packet 4 synchronously with the sync signals from the broadcast TS synchronizer 121.

[0054] If a PID indicating that the packet is a Null packet is described in the TS 41 header unit, the Null packet compressor 122 eliminates this TS 41 header unit as well as the payload unit 42 in the enclosing packet. this TS header unit 41 (i.e., the Null packet), and adds the tip indication byte to the remaining II+RS unit 43 in the Null packet. The Null packet compressor 122 in this way generates the A signal.

[0055] The tip indication byte can generally be called an indication information unit which indicates that the packet is a Null packet. The tip indication byte has a size of 1 byte. Therefore, the tip indication byte size (1 byte) is less than the total size (188 bytes) of the TS header unit 41 and payload unit 42 of a Null packet.

[0056] Null packet compressor 122 outputs signal A to transmit TS packetizer 123.

[0057] Upon receiving the A signal, the transmit TS packer 123 divides the A signal into units of 184 bytes, which is the size of the payload unit 52 of the transmit TS packet 5, starting from the tip of the signal A. The transmit TS packer 123 thus generates the payload unit 52 of each transmit TS packet 5.

The transmit TS packer 123 adds the transmit TS header unit 51 of 4 bytes to the payload unit 52 of each transmit TS packet 5 to generate the transmit TS packet 5 of 188 bytes. Therefore, transmit TS packager 123 generates signal B which includes transmit TS packet 5 (see Fig. 3).

Here, the transmit TS packer 123 places the TS header unit (hereinafter referred to as "first TS header unit") 41 of the first broadcast TS packet 4 into each ISDB-T multiplex frame such that it comes at the end of the payload unit 52 of the first transmit TS packet (hereinafter referred to as "first transmit TS packet") 5 in each frame included in signal B.

[0060] Additionally, the transmit TS packer 123 sets the value of the Payload_Unit_Start_Indicator in the transmit TS header unit 51 in the first transmit TS packet 5 to "1" to indicate that the first transmit TS packet is the boundary between multiplex frames included in the broadcast TS.

[0061] The transmit TS packer 123 outputs the B signal to the rate conversion processor 124.

[0062] To convert the bit rate for signal B into the bit rate for the transmit TS, the rate conversion processor 124 inserts Null packets into signal B to generate the transmit TS. Rate conversion processor 124 sends the transmit TS to satellite line transmitter 13.

[0063] The satellite line transmitter 13 receives the transmit TS and transmits the transmit TS to satellite apparatus 3.

[0064] Satellite apparatus 3 receives the broadcast TS and transmits the broadcast TS to the receiving station system 2.

[0065] The receiving station system 2 includes the satellite line receiver 21, receiver side TS conversion device 22, ISDB-T transmission facility 23, and reference signal generator 24.

[0066] The reference signal generator 24 is a GPS synchronous reference signal generator. The reference signal generator 24 generates 10 MHz reference signals synchronous with GPS signals and outputs the 10 MHz reference signals to the receiver side TS conversion device 22.

[0067] Satellite line receiver 21 can generally be called receiving medium. The satellite line receiver 21 receives the broadcast TS from the satellite apparatus 3. In other words, the satellite line receiver 21 receives the broadcast TS packet 5 from the satellite apparatus 3. Upon receiving the broadcast TS, the satellite line receiver 21 sends the transmit TS to the receiver side TS conversion device 22.

[0068] The receiver side TS conversion device 22, in response to the transmit TS received from the satellite line receiver 21 and the 10 MHz reference signals emitted from the reference signal generator 24, generates a transmission cycle for transmitted TSs synchronous with the 10 MHz reference signals. The receiver side TS conversion device 22 in this way retrieves the broadcast TS from the transmit TS.

[0069] Fig. 1C is a block diagram showing the receiver side TS conversion device 22.

[0070] In Fig. 1C, receiver side TS converting device 22 includes transmit TS synchronizer 221, rate conversion processor 222, transmit TS header remover 223, indication byte search processor edge 224, and transmit TS packer 225. Transmit TS synchronizer 221, rate conversion processor 222, and transmit TS header remover 223 may be called acquisition section 22A. The acquisition section 22A can generally be called the acquisition medium. The tip indication byte lookup processor 224 and broadcast TS wrapper 225 may be called a modify section 22B. Modification section 22B can generally be called modification medium.

[0071] Fig. 4 is a diagram showing signal B', signal A', and broadcast TS that are processed in receiver side TS conversion device 22.

[0072] The acquisition section 22A shown in figure 1C acquires the signal A from the transmit TS packets received by the satellite line receiver 21. The acquisition section 22A outputs the acquired signal A as signal A' to the section of modification 22B.

[0073] If a peak indication byte exists in signal A', the modifying section 22B changes the peak indication byte in TS header unit 41 and payload unit 42 of a Null packet which is the packet of Broadcast TS 4. The modification section 22B in this way changes signal A' in the broadcast TS.

[0074] The transmit TS synchronizer 221 performs synchronization detection for the transmit TS. For example, the transmit TS synchronizer 221 detects the 0x47 values from the transmit TS header units 51 in the transmit TS fed to the receiver side TS converting device 22.

[0075] The transmit TS synchronizer 221 generates synchronous synchronization signals with the detection time of the values 0x47 and outputs the synchronization signals to the rate conversion processor 222.

[0076] The rate conversion processor 222 receives the transmit TS as well as the synchronization signals from the transmit TS synchronizer 221. The rate conversion processor 222 reads information, which is described in the header unit of Transmit TS 51 of each transmit TS packet 5 synchronously with the sync signals from transmit TS synchronizer 221.

[0077] If the PID, which is described in the transmit TS header unit 51, indicates that the packet is a Null packet, the rate conversion processor 222 deletes, from the transmit TS, a packet of transmit TS whose Transmit TS header unit 51 describes the PID indicating that the packet is a Null packet, i.e. it eliminates a Null packet inserted by rate conversion processor 124 in transmit bit rate conversion. Rate conversion processor 222 in this way generates signal B’. Signal B’ represents the same content as signal B.

[0078] Rate conversion processor 222 detects the 0x47 values from the transmit TS header unit 51 in signal B' and generates synchronization information indicating the time to detect the 0x47 values.

[0079] Rate conversion processor 222 outputs signal B' and synchronization information to transmit TS header remover 223.

[0080] The transmit TS header remover 223 receives the B' signal and the synchronization information. In sync with the time indicated by the sync information, the transmit TS header remover 223 reads the payload_unit_start_indicator values from the transmit TS header units 51 in signal B' and detects each transmit TS header unit (hereinafter referred to as "first transmit TS header unit") 51 indicating that the value of the start_of_payload_unit_Indicator=”1”.

[0081] The first transmission TS header unit 51 is followed by the first TS header unit.

Therefore, the transmission TS header remover 223 uses the detection result of the first transmission TS header unit 51 to identify the first transmission TS header unit following the first transmission TS header unit 51.

[0083] The transmit TS header remover 223 then removes transmit TS header units 51 from signal B' to generate signal A'.

[0084] The transmit TS header remover 223 also generates location information to locate the first TS header unit in signal A’. The exemplary location information used may be a synchronous signal with signal A’ such that "H" occurs when the first TS header unit appears in signal A’.

Broadcast TS header remover 223 outputs signal A' and location information to tip indication byte lookup processor 224 and broadcast TS packer 225. Broadcast TS packer 225 may not receive the location information broadcast and can only receive the A' signal broadcast.

The tip indication byte search processor 224 receives the A’ signal and the location information. The tip indication byte search processor 224 detects, from the signal A', the first TS header unit located in the signal A' according to the location information (the TS header unit included in the first packet of broadcast TS of each ISDB-T multiplex frame).

[0087] Once the first TS header unit is detected, the tip indication byte search processor 224 generates the location information of the first TS header unit which locates the first TS header unit in the signal. THE'. Alternatively, the tip indication byte lookup processor 224 may use the location information from the transmit TS header remover 223 as the location information of the first TS header unit.

[0088] Based on the first TS header unit, the tip indication byte search processor 224 also detects subsequent TS header units as well as tip indication bytes with the value 0xB8. Tip indication byte search processor 224 uses the detection result to generate TS header unit location information to locate the TS header units in signal A', and the indication byte location information of tip to locate the tip indication bytes in signal A'.

[0089] TS header unit location information that can be used can be a synchronous signal with signal A’ such that "H" occurs when a TS header unit appears in signal A’. The exemplary tip indication byte location information that can be used may be a synchronous signal with the A’ signal such that “H” occurs when a tip indication byte appears in the A’ signal.

The tip indication byte search processor 224 outputs the first TS header unit location information, the TS header unit location information, and the tip indication byte location information to the broadcast TS packer 225.

The broadcast TS packer 225 uses the TS header unit location information and the edge indication byte location information to check the synchronization of the A' signal with the TS header unit location information. TS and the tip indication byte location information.

[0092] If signal A' synchronizes with the TS header unit location information and the tip indication byte location information, the broadcast TS packer 225 will locate the tip of each multiplex frame included in the TS based on the TS header unit location information. The broadcast TS packer 225 further reproduces the Null packets that were present in the broadcast TS from the ISDB-T MUX device 11 based on the tip indication byte location information. The broadcast TS wrapper 225 in this way retrieves the broadcast TS of 32.5 Mbps in 204 byte format.

Thus, the Null packets which are each a broadcast TS packet of 204 bytes in total, including the 4 byte TS header unit 41, 184 byte payload unit 42, and dummy byte unit 43 of 16 bytes, are retrieved. As a result, the broadcast TS in 204-byte format can be retrieved.

The broadcast TS wrapper 225 sends the retrieved broadcast TS to the ISDB-T transmission facility 23.

[0095] Upon receiving the broadcast TS, the ISDB-T transmission facility 23 converts the broadcast TS into a modulated wave in accordance with ISDB-T and transmits the signal for terrestrial digital broadcast.

[0096] If the A’ signal does not synchronize with the TS header unit location information and the tip indication byte location information, the broadcast TS packer 225 performs predetermined error processing.

[0097] Now the operation will be described.

[0098] First, the operation in which the transmitter side TS converting device 12 converts the broadcast TS into the TS for transmission will be described.

[0099] For the broadcast TS which is fed to the transmitter side TS conversion device 12 (see figure 3), the broadcast TS synchronizer 121 detects the values 0x47 from the TS header units 41, and Null packet compressor 122 eliminates both the TS header unit (4 bytes) and payload unit 42 (184 bytes) from each Null packet in the broadcast TS.

[0100] Null 122 packet compressor adds the tip indication byte (1 byte) to the remaining II+RS unit 43 (16 bytes) to generate signal A shown in Figure 3. Null 122 packet compressor outputs the signal A for transmit TS packer 123.

[0101] Upon receiving the A signal, the transmit TS packer 123 divides the A signal into units of 184 bytes, starting from the data end, to generate the payload unit 52 of each transmit TS packet. The transmit TS packer 123 adds the transmit TS header unit 51 (4 bytes) to the payload unit 52 of each transmit TS packet to generate 188 byte transmit TS packets. Thus, the transmit TS packer 123 generates the B signal which includes transmit TS packets 5 (see Fig. 3).

[0102] The transmit TS packer 123 places the first TS header unit (with the TS header unit of the first broadcast TS packet 4 in each ISDB-T multiplex frame) 41 such that it comes at the edge of the payload unit 52 of the first transmit TS packet (the first transmit TS packet in each frame included in signal B) 5.

[0103] The transmit TS packer 123 then sets the value of the payload_unit_start_indicator in the transmit TS header unit 51 in the first transmit TS packet 5 to "1" to indicate that the first transmit TS packet is the threshold between multiplex frames included in the broadcast TS.

[0104] The transmit TS packer 123 outputs the B signal to the rate conversion processor 124.

[0105] Rate conversion processor 124 receives the B signal and, to convert the bit rate for signal B into the bit rate for the transmit TS, inserts Null packets into the signal.

B to generate the broadcast TS.

[0106] As a result, the broadcast TS in 204-byte format can be converted into a transmittable form via a transmission path for broadcast TS packets in 188-byte format, and the transmission amount of 32.5 Mbps can be reduced.

[0107] The transmit TS generated by the transmitter side TS converting device 12 is output to the satellite line transmitter 13, which transmits the transmit TS to the satellite apparatus 3. The satellite apparatus 3 transmits the Transmit TS to Satellite Line Receiver 21.

[0108] In the following, the operation in which the receiver side TS conversion device 22 retrieves the broadcast TS from the transmit TS will be described.

[0109] Receiver side TS converting device 22 receives the transmit TS received by satellite line receiver 21.

[0110] The transmit TS synchronizer 221 detects the 0x47 values from the transmit TS header units 51 in the transmit TS fed to the receiver side TS converting device 22 and generates time-synchronous synchronization signals in which 0x47 values will be detected. The transmit TS synchronizer 221 outputs the synchronization signals to the rate conversion processor 222.

[0111] The rate conversion processor 222 receives the transmit TS fed to the receiver side TS conversion device 22, and the synchronization signals from the transmit TS synchronizer 221. The rate conversion processor 222 eliminates Null packets inserted by rate conversion processor 124 in transmit bit rate conversion and generates signal B' shown in Fig. 4(a).

[0112] Having generated signal B', rate conversion processor 222 detects the 0x47 values from the transmit TS header units 51 in signal B' to generate synchronization information indicating the time at which the 0x47 values will be detected.

[0113] Rate conversion processor 222 outputs signal B' and synchronization information to transmit TS header remover 223.

[0114] The transmit TS header remover 223 receives the B' signal and the synchronization information. In sync with the time indicated by the synchronization information, the transmission TS header remover 223 reads the values of the payload_unit_start_indicator from the transmission TS header units 51 in signal B' and detects each transmission TS header unit 51 indicating the value of the Payload_Unit_Start_Indicator=”1” (the first transmit TS header unit).

[0115] Having detected the first transmit TS header unit 51, the transmit TS header remover 223 uses the result of detecting the first transmit TS header unit to identify the first transmit TS header unit following the first transmit TS header unit 51.

[0116] The transmit TS header remover 223 then removes the transmit TS header units 51 from signal B' to generate signal A'.

[0117] After generating the A’ signal, the transmit TS header remover 223 generates the location information to locate the first TS header unit in the A’ signal.

[0118] Having generated the location information, the broadcast TS header remover 223 outputs the A’ signal and the location information to the tip indication byte lookup processor 224 and broadcast TS packer 225.

[0119] The tip indication byte search processor 224 receives the A’ signal and the location information. The tip indication byte search processor 224 detects, from the signal A', the first TS header unit located in the signal A' according to the location information (the TS header unit included in the first packet of broadcast TS of each ISDB-T multiplex frame).

[0120] Once the first TS header unit is detected, the tip indication byte search processor 224 generates the location information of the first TS header unit.

[0121] Then, based on the first TS header unit, the tip indication byte search processor 224 detects the subsequent TS header units as well as the tip indication bytes with the value 0xB8. The tip indication byte search processor 224 generates the TS header unit location information and the tip indication byte location information.

[0122] The tip indication byte search processor 224 outputs the first TS header unit location information, the TS header unit location information, and the tip indication byte location information to the broadcast TS packer 225.

[0123] The broadcast TS packer 225 receives the A' signal, the location information, the location information of the first TS header unit, the location information of the TS header unit, and the location information of tip indication byte. The broadcast TS packer 225 uses the TS header unit location information and the edge indication byte location information to check the synchronization of the A' signal with the TS header unit location information and the tip indication byte location information.

[0124] If signal A' synchronizes with the TS header unit location information and the tip indication byte location information, the broadcast TS packer 225 locates the tip of each multiplex frame included in the TS based on the location information of the first TS header unit. The broadcast TS packer 225 further reproduces the Null packets that were present in the broadcast TS from the ISDB-T MUX device 11 based on the tip indication byte location information. The broadcast TS wrapper 225 in this way retrieves the broadcast TS of 32.5 Mbps in 204 byte format.

[0125] In the exemplary embodiment, if a TS header unit is present at the end of the A' signal, the broadcast TS packer 225 splits, from the A' signal, a signal starting at the TS header unit and ending in the 204th byte of the TS header unit. This signal split from signal A’ is treated as a broadcast TS packet.

[0126] If a TS header unit is present at the end of signal A' from which the broadcast TS packet has been split, a broadcast TS packer 225 splits, from signal A', a starting signal in the TS header unit and ending on the 204th byte from the TS header unit. This signal split from signal A’ is treated as a broadcast TS packet.

[0127] If a tip indication byte is present at the end of signal A', the broadcast TS packer 225 deletes the tip indication byte and adds the TS header unit 41 with the Null packet PID (ID of the package) and payload 42 at the tip of the signal A'. The broadcast TS packer 225 leaves the II+RS unit 43 added after the tip indication byte and stores the 184-byte compressed invalid data in the payload unit 42. The broadcast TS packer 225 divides, from the signal A', the Null packet which includes the TS header unit 41 with the Null packet PID, payload unit 42 storing the invalid data, and II+RS 43 as the broadcast TS packet.

[0128] If a peak indication byte is present from the tip of the signal A' from which the broadcast TS packet was split, the broadcast TS packer 225 deletes the peak indication byte and adds the unit of TS header 41 with PID of Null packet and payload unit 42 at signal end A'. The broadcast TS packer 225 leaves the II+RS unit 43 added after the tip indication byte and stores the compressed invalid data of the 184 bytes in the payload unit 42. The broadcast TS packer 225 divides, from of signal A', the Null packet which includes the TS header unit 41 with the PID of the Null packet, payload unit 42 storing the invalid data, and II+RS 43 as a broadcast TS packet.

[0129] Thus, the broadcast TS in 204-byte format is retrieved.

[0130] Since the transmission cycle for the broadcast TS retrieved by the broadcast TS packer 225 is synchronized with the GPS signals, as with the broadcast TS in broadcast station system 1, it fully synchronizes with the transmission cycle generated by the ISDB-T MUX 11 device.

[0131] Also, the position of each packet in the broadcast TS (the ISDB-T multiplex frames) retrieved by the broadcast TS packer 225, completely matches the position of each packet in the broadcast TS (the ISDB-T multiplex frames) ) generated by the ISDB-T MUX 11 device.

[0132] Therefore, the broadcast TS structure (the ISDB-T multiplex frame structure) retrieved by the broadcast TS wrapper 225 also completely matches the broadcast TS structure (the ISDB-T multiplex frame structure) generated by the ISDB-T device MUX 11. Also, PCR packets are placed in the same positions in the broadcast TS which is retrieved by the broadcast TS packer 225 and in the broadcast TS which is generated by the ISDB-T device MUX 11, such that values PCR in PCR packages do not need to be fixed.

[0133] The broadcast TS retrieved by the receiver side TS conversion device 22 is fed to the ISDB-T transmission facility 23.

[0134] According to the exemplary configuration, if the broadcast TS includes a Null packet which is a kind of broadcast TS packet 4, the generation section 12A in broadcast station system 1 converts the TS header unit 41 and payload unit 42 in the Null packet, i.e. the compression target portion, in a tip indication byte. The generation section 12A in this way compresses the broadcast TS to generate signal A which is a data signal. Transmit section 12B transmits signal A using transmit TS packet 5.

[0135] Thus, the A signal in which Null packets in the broadcast TS were compressed is transmitted using the broadcast TS packets. This allows for the reduction of the transmission amount and the compression of the transmission band, compared to a case where the broadcast TS in which Null packets in the broadcast TS were not compressed is transmitted using the broadcast TS packets.

[0136] Also, the number and arrangement of packets in the broadcast TS are kept in the A signal. Therefore, the configuration of the multiplex frames that includes the packets in the broadcast TS is kept in the A signal.

[0137] In the exemplary configuration, the satellite line receiver 21 in the receiving station system 2 receives broadcast TS packets 5 transmitted from the broadcast station system 1. The acquisition section 22A acquires the signal A from the Transmit TS packets 5 received by the satellite line receiver 21 and output signal A as signal A'. If a peak indication byte exists in signal A', the modifying section 22B changes the peak indication byte in the TS head unit 41 and payload unit 42 of a Null packet which is broadcast TS packet 4. The modification section 22B in this way changes the signal A' in the broadcast TS.

[0138] As described above, the number and arrangement of packets in the broadcast TS are kept in signal A. Therefore, the configuration of the multiplex frames that include the packets in the broadcast TS is kept in signal A. Consequently, the station system Receiver 2 can reproduce the broadcast TS only by recovering the Null packets compressed in signal A without taking the configuration of the multiplex frames into account.

[0139] Thus, the receiving station system 2 does not need to regenerate the frame configuration pattern based on the transmit TS and reconstruct the multiplex frames based on the regenerated frame configuration pattern.

[0140] Since the number and arrangement of packets in the broadcast TS are maintained in signal A, the positions where the PCR packets are multiplexed are the same in both the reproduced broadcast TS and the original broadcast TS. Therefore, the need for a PCR correction circuit to correct information in PCR packets can be eliminated in transmit station system 1 and receive station system 2.

[0141] Although a transmit TS packet has a size of 188 bytes in the above exemplary configuration, the size of a transmit TS packet can be changed as appropriate. For example, a broadcast TS packet might have a size of 204 bytes.

[0142] Although the broadcast TS for digital terrestrial broadcasting is used as the broadcast TS in the above exemplary configuration, other types of broadcast TS may be used as appropriate. For example, a broadcast TS for digital transmission BS/CS can be used as the broadcast TS.

[0143] Although the ISDB-T compliant broadcast TS is used as the broadcast TS for digital terrestrial broadcasting in the above exemplary configuration, other types of broadcast TS for digital terrestrial broadcasting may be used as appropriate.

[0144] Instead of receiving station system 2 in the above exemplary configuration, a relay system that retransmits the broadcast TS can be used.

[0145] If RS error correction is not required in ISDB-T transmission facility 23 of receiving station system 2, Null 122 packet compressor may not let the entire dummy byte unit (16 bytes) remain in the compression of the Null packets but can let only the ISDB-T piece of information (8 bytes) remain in the dummy byte unit. This allows for further reduction in the amount of transmission and additional compression of the transmission bandwidth.

[0146] In the exemplary configuration, the first packet of each ISDB-T multiplex frame comes in the payload of the first packet in each frame in the transmit TS. However, the relationship between the first packet of each ISDB-T multiplex frame and the first packet of each frame in the transmit TS is not limited to the above description.

[0147] For example, each certain number of TS header units of the broadcast TS can be placed to follow a transmit TS header unit of the broadcast TS, and the value of the Payload_Unit_Start_Indicator in each TS header unit of broadcast followed by a TS header unit of the broadcast TS can be set to “1”.

[0148] Although the transmit TS is transmitted via satellite apparatus 3 in the exemplary configuration, the transmit TS can be transmitted without the intervention of satellite apparatus 3.

[0149] In the exemplary configuration, broadcast station system 1 includes ISDB-T MUX 11 device and reference signal generator 14. However, broadcast station system 1 may not include ISDB-T MUX 11 device and reference signal generator 14. In this case, the transmitter side TS converting device 12 in the broadcast station system 1 can receive the broadcast TS from the ISDB-T MUX device 11.

[0150] In the exemplary configuration, the portion including the TS header unit 41 and payload unit 42 in a Null packet which is a kind of broadcast TS packet is used as the compression target portion. However, the target compression portion can be changed as appropriate. For example, as the compression target portion, only the TS header unit 41 in a Null packet which is a kind of broadcast TS packet can be used, or a combination of TS header unit 41 and part of the unit of 42 payload in a Null packet which is a kind of broadcast TS packet can be used.

[0151] The exemplary configuration is applicable to transmission systems for digital terrestrial broadcast TSs or BS/CS digital broadcast TSs that use multiple lines such as satellite lines and FPU (Field Imaging Unit) lines.

[0152] The present invention has been described so far with reference to the exemplary configuration, but the present invention is not limited to the exemplary configuration. Various modifications understandable to those skilled in the art can be made to the configuration and details of the present invention defined in the claims without departing from the scope of the present invention.

[0153] This patent application is based on and claims priority from Japanese Patent Application No. 2010-04120, filed February 25, 2010, the disclosure of which is incorporated herein in its entirety by reference. Description of numbers 1 broadcast station system 11 ISDB-T MUX device 12 transmitter side TS conversion device 12A generation section 12B transmission section 121 broadcast TS synchronizer 122 packet compressor Null 123 transmission TS packer 124 Rate Conversion Processor 13 Satellite Line Transmitter 14 Reference Signal Generator 15 Receive Station System 21 Satellite Line Receiver 22 Receiver Side TS Conversion Device 22A Acquisition Section 22B Modification Section 221 Synchronizer Transmit TS 222 Rate Conversion Processor 223 Transmit TS Header Remover 224 Tip Indication Byte Search Processor 225 Broadcast TS Packer 23 ISDB-T Transmission Facility 24 Reference Signal Generator 3 Satellite Apparatus .

Claims (7)

1. Transmission apparatus, comprising a broadcast stream including frames for generating a data signal, each frame including transmission packets, each transmission packet including a header unit, a data unit, and an attached information unit, and transmitting the data signal using transmission packets, the transmission apparatus, comprising: - generating means for compressing the broadcast stream to generate the data signal, if a Null packet which is a kind of transmission packet is present in the broadcast stream, converting a compression target portion into an indicating information unit which has a size smaller than a compression target portion size and which indicates that the packet is a Null packet, the compression target portion being at least part of a portion including the header unit and the data unit of the Null packet; and - transmission means for transmitting the data signal using the transmission packets, characterized in that the compression target portion is a portion including the header unit and the data unit of the Null packet. 2. Transmission apparatus according to claim 1, characterized in that: - the attached information unit describes control information defined in accordance with ISDB-T and error correction information in accordance with ISDB-T, and - if the Null packet is present in the broadcast stream, the generating means compresses the broadcast stream to generate the data signal by converting the target compression portion in the indicating information unit and eliminating a portion describing the error correction information in the unit of information attached in the Null package. 3. Receiving apparatus, characterized in that it comprises: - receiving means for receiving transmission packets from the transmission apparatus as identified in any one of claims 1 or 2; - acquisition means for acquiring the data signal from the transmission packets received by the receiving means; and - modifying means for modifying the data signal in a broadcast stream, if the indicating information unit is present in the data signal acquired by the acquisition means, changing the indicating information unit at the compression target portion. 4. Communication system, characterized in that it comprises the transmission apparatus as identified in any one of claims 1 or 2, and the receiving apparatus as identified in claim 3. 5. Method of transmission, in a transmission apparatus which compresses a broadcast stream including frames to generate a data signal, each frame including transmission packets, each transmission packet including a header unit, a data unit, and a attached information unit, and which transmits the data signal using transmission packets, the transmission method comprising: - if a Null packet which is a kind of transmission packet is present in the broadcast stream, compressing the broadcast stream to generate the data signal converting a compression target portion into an indicating information unit which has a size less than a compression target portion size and which indicates that a packet is a Null packet, the compression target portion being at least part of a portion including the header unit and the data unit of the Null packet; and - transmitting the data signal using the transmit packets, characterized in that the compression target portion is a portion including the header unit and the data unit of the Null packet. 6. Transmission method according to claim 5, characterized in that - the attached information unit describes control information defined in accordance with ISDB-T and error correction information defined in accordance with ISDB-T; and - the generation comprises, if the Null packet is present in the broadcast stream, compressing the broadcast stream to generate the data signal by converting the target compression portion into the indication information unit and eliminating a portion describing the correction information of error in the unit of information attached to the Null package. 7. Method of conversion in a receiving apparatus, characterized in that it comprises: - receiving the transmission packets transmitted from the transmission apparatus, as identified in any one of claims 1 or 2; - acquire the data signal from the transmission packets; and - if the indicating information unit is present in the data signal, changing the data signal in a broadcast stream by modifying the indicating information unit in the compression target portion.

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