JP5642497B2 - Digital data transmitting apparatus, receiving apparatus and program - Google Patents

Description

  The present invention relates to a technique for time-division-multiplexing a plurality of digital data in units of packets to form a frame and transmitting it in a system for transmitting digital data in a packet format such as an MPEG-2 TS signal.

  Conventionally, a plurality of MPEG-2 TSs (transport streams defined in ISO / IEC (International Organization for Standardization: International Electrotechnical Commission) 13818-1) are kept independent. Thus, a method of transmitting a transmission line assuming a single TS has been proposed (see, for example, Patent Document 1 and Non-Patent Document 1).

  In this transmission method, a periodic frame structure is added to a TS packet (fixed length (188 bytes) packet starting with a synchronization byte (0x47) or a packet obtained by adding a fixed length parity byte) sequence in a transmission apparatus. The TS packet sequence is multiplexed by using the slot position information. The receiving apparatus receives the multiplexed TS packet sequence frame, and uses the slot allocation information to separate the TS packet sequence. The point of this transmission method is that the frame header includes the necessary synchronization word data (synchronization information) and slot allocation information indicating the position in the frame where each TS is stored, and is in the TS packet format. It has become. Hereinafter, data multiplexed in a frame is referred to as frame format data.

  In addition to the method described in the above-mentioned Patent Document 1 or Non-Patent Document 1 for transmitting to a transmission path that assumes a single TS, a plurality of TSs including a high-speed TS that can be transmitted by one carrier wave (channel). There is also proposed a method of multiplexing the TSs in the frame shown in Patent Document 1 or Non-Patent Document 1 and performing frequency multiplexing transmission through a plurality of channels (for example, see Patent Document 2). In this transmission method, high-speed TS is multiplexed into a frame in a transmission apparatus, frame format data having a speed N times the transmission speed per channel is generated, and N-divided in units of packets and divided into N channels. To be transmitted. The receiving apparatus restores frame format data at a rate N times the transmission rate per channel, and generates an original TS from the restored frame format data. Here, in the transmission apparatus, when the TS is multiplexed into the frame, (N−1) null packets are multiplexed after the header, and when the N is divided, the (N−1) ) Null packets are replaced with a duplicate of the header. Thus, the frame is configured such that one header is included in each of the divided frame format data. The point of this method is that the receiving apparatus adjusts the delay difference between channels based on the header and restores frame format data at a rate N times the transmission rate per channel.

  On the other hand, the speed of the TS to be transmitted is measured, and the channel allocation for each TS is determined based on the number of TS divisions that need to be divided into a plurality of channels and the number of channels that transmit TS that do not require division. Techniques have been proposed (see, for example, Patent Document 3). This technique is different from Patent Document 2 in that the receiving apparatus needs to receive only the channel through which the TS to be extracted is transmitted.

  In addition, in the receiving apparatus, it is possible to receive only the channel through which the TS to be extracted is transmitted, and to suppress the total number of channels necessary for transmitting all the TSs to be smaller than that of the above-mentioned Patent Document 3. Techniques have been proposed (see, for example, Patent Document 4). In this technique, a transmission apparatus generates frame format data having a rate N times the transmission rate per channel, and divides the packet into N and transmits it on N channels. However, unlike the technique of Patent Document 2 described above, the header is generated and transmitted independently for each channel. Therefore, the receiving apparatus restores the frame format data at a rate N times the transmission rate per channel. There is no need to do. Further, by preparing in advance information on the number of slots and slot positions to be allocated and information on channels to be allocated based on the number of original TSs and transmission speed, the number of divisions of each TS is reduced, and more than in Patent Document 3. It is possible to reduce the number N of necessary channels.

  By the way, a technique for multiplexing and transmitting a single TS described in the above-mentioned Patent Document 1 and Non-Patent Document 1, or a plurality of TSs described in Patent Documents 2 to 4 described above via a plurality of channels. In the frequency multiplex transmission technology, the receiving device needs to regenerate a desired clock when outputting a TS requested by the user. Techniques aimed at reducing the scale of a circuit that reproduces the clock have been proposed (see, for example, Patent Documents 5 and 6).

  In the technique of Patent Document 5, the transmission device rewrites the value of PCR (program clock reference) in advance in order to match the transmission rate of frame format data for a TS that is multiplexed into a frame and transmitted in one channel, When receiving the TS from the frame format data, the receiving device replaces the TS packet other than the requested TS with a null packet and outputs it. In this technique, regardless of the number of slots to which TS is assigned in a frame, the receiving apparatus does not need to output TS at the same speed as the transmission speed of frame format data and reproduce the original TS speed. The point is that the clock recovery process is simple.

  Further, in the technique of Patent Document 6, when the transmission device multiplexes a frame and transmits it in one channel, the number of slots to be allocated is a factor of the number of slots in one frame, or if it cannot be a factor, A null packet is added so that the number of slots with the nearest factor is added, the PCR value is rewritten, and the null packet is removed again before transmission. The receiving apparatus adds a null packet to the extracted TS as necessary, and outputs it. In this case, the receiving device regenerates the clock from the transmission speed of the frame format data, and divides this clock by an integer to regenerate the original TS clock. Therefore, the point of this technique is that the process of reproducing the clock of the original TS is easily performed in the receiving apparatus.

  Japanese Patent Application Laid-Open No. 2004-228688 describes a method of reducing the scale of the clock recovery circuit by eliminating the process of recovering the clock of the original TS. The first method is a transmission rate per channel with respect to TS multiplexed in M frames (M is an integer equal to or less than N) among N frames transmitted by N transmission channels. The value of the PCR is rewritten in accordance with the speed of M times, and when the receiving apparatus extracts the requested TS from the M frame format data, the TS packet other than the TS is replaced with a null packet and output. In addition, the second method is a method in which the transmission apparatus per channel is multiplexed with respect to TS multiplexed in M frames (M is an integer equal to or less than N) out of N frames transmitted by N channels. The value of the PCR is rewritten in accordance with a speed N times the transmission speed, and the receiving apparatus replaces TS packets other than the requested TS with null packets when extracting the requested TS from the M frame format data. , A null packet corresponding to the number of packets transmitted through (N−M) channels is generated, added to the TS, and output. These methods enable the receiving apparatus to take out TS at the same speed as the speed of M times (method 1) or N times (method 2) per channel, regardless of the speed of the original TS. There is an advantage that the process of reproducing the speed of the TS becomes unnecessary.

Japanese Patent No. 3051729 Japanese Patent No. 3991307 Japanese Patent No. 4111438 JP 2010-177858 A Japanese Patent No. 4374107 JP-A-11-177516

ITU-T Rec. J. et al. 183

  However, these conventional techniques have the following problems. For example, in the technique of Patent Document 5, even when the original TS speed is low, the output TS speed is the same as the transmission speed of the frame format data. There is a problem that the power consumption of the entire decoder circuit increases.

  Further, in the technique of Patent Document 6, when the number of slots in one frame is a prime number, or when the factor of the number of slots in one frame is small, it is output even when the speed of the original TS is low. There is a problem that the speed of the TS increases, and the power consumption of the entire receiver and decoder circuits increases.

  Further, in the method 2 described in Patent Document 4, even when the original TS rate is low, the output TS rate is N times the transmission rate per channel, and thus the receiving device In addition, there is a problem that the power consumption of the entire decoder circuit increases.

  Further, in Method 1 described in Patent Document 4, it is possible to take out TS at a speed equal to or less than N times the transmission speed per channel according to the number of channels transmitting TS. The speed of the TS to be output can be reduced as compared with the technique 2. For this reason, although the power consumption of the entire receiver and decoder circuits can be reduced, there is a problem that the number of clocks that need to be recovered by the clock recovery circuit of the receiver is N at most and the scale of the clock recovery circuit increases. there were.

  Accordingly, the present invention has been made to solve the above-described problems, and an object of the present invention is to suppress the speed of the TS output from the receiving apparatus in a system in which a plurality of TSs are multiplexed and transmitted in a frame. An object of the present invention is to provide a digital data transmission device, a reception device, and a program that can reduce the scale of a clock recovery circuit used in the reception device.

In order to achieve the object, the invention of claim 1 inputs a plurality of digital data, time-division-multiplexes the plurality of digital data in units of packets, constitutes a frame consisting of a header slot and a data slot, A slot allocating unit for determining a slot allocation number and a slot position for each digital data when the plurality of digital data is stored in a data slot in the frame, A header generation unit that generates a header based on the slot allocation number and slot position determined by the slot allocation unit; and a PCR rewrite unit that rewrites a value of a PCR (program clock reference) included in the digital data; Generated by the header generator A plurality of digital data in which the PCR value is rewritten based on the slot allocation number and slot position determined by the slot allocation unit. stored in the slot, comprising: a multiplexing unit for forming a frame by multiplexing, and the PCR rewriting unit, a plurality of speed in the transmission rate per transmission rate or 1 channel per slot as a unit is, the Based on the correspondence information, which is defined in advance as correspondence information corresponding to the input speed of the digital data input by the transmission device, and includes any speed independent of the speed corresponding to the number of slots constituting one frame. Among the individual speeds, the minimum speed must be equal to or higher than the input speed of the digital data input by the transmitter. The digital data output by the receiving device that receives the frame is used as an output speed, and the PCR value is rewritten to match the output speed.

Further, the invention of claim 2 is the transmission device according to claim 1, wherein a plurality of rates included in the correspondence information provided in the PCR rewriting unit is set to a predetermined positive integer for the transmission rate per slot. An arbitrary value unrelated to the speed corresponding to the number of slots constituting the one frame obtained by multiplication, and a value obtained by multiplying the transmission speed per slot by the predetermined positive integer factor. It is characterized by that.

Further, the invention of claim 3 is the transmission device according to claim 1, wherein a plurality of rates included in the correspondence information provided in the PCR rewriting unit are set to a predetermined positive integer as a transmission rate per channel. An arbitrary value unrelated to the speed corresponding to the number of slots constituting the one frame, obtained by multiplication, and a value obtained by multiplying the transmission speed per channel by the predetermined positive integer factor. It is characterized by that.

  The invention according to claim 4 is the transmitting apparatus according to claim 1, wherein the PCR rewriting unit receives the frame of digital data after adding a null packet to the digital data input by the transmitting apparatus. Assuming that the digital data is output at the output speed, the number and position of null packets added to the digital data are determined based on the slot allocation number determined by the slot allocation unit, and the null packet is determined. The PCR value is rewritten so as to match the speed of the added digital data.

  Further, the invention according to claim 5 is the transmission device according to claim 4, wherein the PCR rewriting unit specifies the correspondence information in which the number of slot assignments and the number of slots after the addition of a null packet are defined correspondingly. And the number of null packets is determined based on the number of slot allocations determined by the slot allocation unit according to the correspondence information.

  Further, the invention according to claim 6 is the transmission device according to claim 4 or 5, wherein the PCR rewriting unit performs the data packet of the original digital data with respect to the assumed digital data packet sequence after the addition of the null packet. And rule information for allocating a null packet, and in accordance with the rule information, the data packet or null packet is determined based on the number of data packets and null packets to be allocated and the number of data packets and null packets already allocated. The position of the null packet is determined by allocating to the packet sequence.

  The invention according to claim 7 is the transmitter according to claim 5, wherein the number of slots after adding a null packet included in the correspondence information provided in the PCR rewriting unit is set to a predetermined positive integer and the predetermined positive number. It is characterized by being an integer factor of.

  The invention of claim 8 is the transmitter according to claim 5, wherein the number of slots after adding a null packet included in the correspondence information provided in the PCR rewriting unit is a value in units of the number of slots of one frame. It is characterized by that.

  The invention of claim 9 is the transmitter according to claim 5, wherein the number of slots after adding a null packet included in the correspondence information provided in the PCR rewriting unit is set to a predetermined positive number for the number of slots in one frame. A value obtained by multiplying an integer and a value obtained by multiplying the number of slots in one frame by the factor of the predetermined positive integer are characterized.

Furthermore, the invention of claim 10 receives the frame transmitted by the transmission device according to any one of claims 1 to 9, and separates digital data requested by a user from the frame. An output receiving device that detects a header in the frame and generates a slot allocation number and a slot position of the digital data from the header, and a slot of the digital data generated by the header detection unit A separation unit that outputs the digital data requested by the user separately from the frame based on the number of assignments and the slot position, and the separation unit outputs the digital data based on the transmission rate of the frame. A clock recovery unit for recovering a necessary clock, and the separation unit includes a P of the transmission device. With corresponding information identical correspondence information and having the R rewriter, a plurality of speed in the transmission rate per transmission rate or 1 channel per slot as a unit is, the input speed of the digital data to which the transmission device to input Based on the correspondence information including an arbitrary speed unrelated to the speed corresponding to the number of slots constituting one frame, and the digital data input by the transmitting device. Of these, the output speed is a minimum speed that is equal to or higher than the speed of the digital data requested by the user, and the separated digital data is output at the output speed.

  Furthermore, the invention of claim 11 resides in a transmission program for causing a computer to function as the transmission device according to any one of claims 1 to 9.

  According to a twelfth aspect of the present invention, there is provided a receiving program for causing a computer to function as the receiving device according to the tenth aspect.

  As described above, according to the present invention, in a system in which a plurality of transport streams are multiplexed into a frame and transmitted, the speed of TS output from the receiving apparatus can be kept low, and the clock used in the receiving apparatus The scale of the reproduction circuit can be reduced.

It is a block diagram which shows the structure of the transmitter by Embodiment 1 (Example 1) of this invention. It is a figure which shows the example of the slot position determined by a slot allocation part. It is a figure which shows the example of the header produced | generated by the header production | generation part. It is a flowchart which shows the process of PCR rewriting part. It is a figure explaining the example of a response | compatibility with the slot allocation number and the number of slots after a null packet addition. It is a figure explaining the example of a calculation of the arrangement order of TS packet and the added null packet. It is a figure explaining the relative time interval about the packet sequence after a null packet addition, and the original TS packet sequence. It is a block diagram which shows the structure of the receiver by Embodiment 1 (Example 1) of this invention. It is a flowchart which shows the process of a isolation | separation part. It is a figure which shows the packet sequence which consists of a null packet at the time of remove | excluding the packet of TS2 from 1 frame in the modification 1 of Example 1. FIG. It is a figure explaining the example of calculation of the position of the null packet deleted in the modification 1 of Example 1. FIG. It is a figure which shows the position of the null packet deleted in the modification 1 of Example 1. FIG. It is a figure which shows the position of the null packet deleted in the packet sequence which replaced the packet other than TS2 in the modification 1 of Example 1 with the null packet. It is a figure explaining the relative time interval about the packet sequence after the null packet deletion in the modification 1 of Example 1, and the original TS packet sequence. It is a figure which shows the packet sequence which replaced the packet other than TS3 in the modification 1 of Example 1 with the null packet. It is a figure explaining the example of calculation of the arrangement order of the packet in a flame | frame and the added null packet in the modification 1 of Example 1. FIG. It is a figure which shows the example which added the null packet to the packet sequence which replaced the packet other than TS3 in the modification 1 of Example 1 with the null packet. It is a figure explaining the example of a response | compatibility with the slot allocation number in the modification 2 of Example 1, and the slot number after adding a null packet. It is a block diagram which shows the structure of the transmitter by Embodiment 2 (Example 2) of this invention. It is an example of the slot position determined by a slot allocation part. It is a figure which shows the example of the header of each flame | frame produced | generated by the header production | generation part. It is a figure which shows the example of a response | compatibility with the sum total of the slot allocation number, and the slot number after a null packet addition. It is a figure explaining TS division | segmentation process by the multiplexing part of a transmitter, and TS synthetic | combination process (process with respect to TS1) by the isolation | separation part of a receiver. It is a figure explaining TS division | segmentation process by the multiplexing part of a transmitter, and TS synthetic | combination process (process with respect to TS2) by the isolation | separation part of a receiver. It is a block diagram which shows the structure of the receiver by Embodiment 2 (Example 2) of this invention. It is a figure which shows the example of a response | compatibility with the total of the slot allocation number in the modification 1 of Example 2, and the number of slots after a null packet addition.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In the present invention, the transmission device defines the speed of the TS output by the reception device, rewrites the PCR so as to match the speed, multiplexes the TS into a frame, and transmits the received frame from the received frame. The TS requested by the user is separated, and the TS is output at an output speed defined by the transmission apparatus. In this case, the speed of the TS output by the receiving apparatus is consistent with the PCR written in the TS. The first embodiment described below is an example in which the present invention is applied to a system that transmits a plurality of TSs using one channel, and the second embodiment is an application of the present invention to a system that transmits a plurality of TSs using a plurality of channels. This is an example.

  First, Example 1 will be described. The first embodiment is an example of a system that transmits a plurality of TSs by one channel. In the following, description will be given separately for a transmitting device and a receiving device.

[Transmitter]
First, the transmission apparatus according to the first embodiment will be described. FIG. 1 is a block diagram illustrating a configuration of the transmission apparatus according to the first embodiment. The transmission device 1-1 includes a slot assignment unit 10, PCR rewriting units 11-1 to 11-I, a header generation unit 12, and a multiplexing unit 13.

  The transmission apparatus 1-1 inputs I TS1 to TSI to be transmitted, and acquires speed information 1 to I indicating the speed of each input TS. Note that I TS1 to TSI input by the transmission device 1-1 are speed-converted in advance so that each TS is assigned to each data slot of one frame in a slot assignment unit 10 to be described later. It is assumed that the value has also been rewritten.

  The slot allocation unit 10 receives the speed information 1 to I, determines the number of slots and the slot position to be allocated to each TS, determines the slot allocation number and the slot position of each TS, the PCR rewriting units 11-1 to 11-I, the header The data is output to the generation unit 12 and the multiplexing unit 13.

  Each of the PCR rewriting units 11-1 to 11-I inputs TS1 to TSI, and also inputs the slot allocation number and slot position of the TS from the slot allocation unit 10, and the slot allocation number and slot for TS1 to TSI. Based on the position, the number and position of null packets to be inserted into the TS by the receiving apparatus 2-1 described later are determined. The null packet is inserted when the receiving device 2-1 outputs the requested TS separately from the frame. Then, the PCR rewriting units 11-1 to 11-I determine the PCR value of each TS based on the number and position of null packets inserted by the receiving device 2-1, so as to match the speed after adding the null packets. And TS1 to TSI with the rewritten PCR value are output to the multiplexing unit 13. Here, the PCR is program time reference value information obtained by sampling a value (time) generated by the clock of the transmission device 1-1 at a predetermined interval, and a decoder provided at a subsequent stage of the reception device 2-1 described later is It is used when decoding TS output from the receiving device 2-1.

  That is, the PCR rewriting units 11-1 to 11-I describe the input TS1 to TSI at a minimum speed that is equal to or higher than the input TS speed defined in the correspondence information described later and is described later. The output speed output by the receiving device 2-1 is determined, and the PCR value of each TS is rewritten so as to match the output speed.

  The header generation unit 12 inputs the slot allocation number and slot position of each TS from the slot allocation unit 10, and identifies TS identification information (correspondence table of TS_id (TS identifier) and original_network_id (original network identifier) and relative TS number). A header including slot allocation information including the relative TS number of the TS stored in each slot is generated, and the generated header is output to the multiplexing unit 13.

  The multiplexing unit 13 inputs TS1 to TSI in which the PCR values are rewritten from the PCR rewriting units 11-1 to 11-I, inputs the slot allocation number and slot position of each TS from the slot allocation unit 10, and the header A header is input from the generation unit 12. Then, the multiplexing unit 13 multiplexes the input header and TS1 to TSI into frames based on the input slot allocation number and slot position of each input TS, and transmits the multiplexed frame to the receiving device 2-1 described later. To do.

(Concrete example)
Next, specific operations of each unit in the transmission device 1-1 illustrated in FIG. 1 will be described with specific examples. The TS input by the transmission apparatus 1-1 is three (I = 3), the speed of each TS is TS1 = 1 Mbps, TS2 = 2 Mbps, TS3 = 9 Mbps, and the transmission path has a transmission band of 13 Mbps. To do. The frame is assumed to be composed of one header slot and 12 data slots.

  In this specific example, the data transmission rate when 1 slot is used is 13 Mbps / 13 slots = 1 Mbps. The total speed of all TSs is 12 Mbps, and all TSs can be transmitted in a total of 12 slots.

  The slot allocation unit 10 inputs the speed information 1 to 3 of TS1 to TS3, and sets the number of slots in the frame allocated to TS1 to TS3 based on the speed information 1 to 3 as 1 slot, 2 slots, and 9 slots, respectively. decide. The number of slot assignments is determined according to the speed magnitude of the speed information 1 to 3 for the number of data slots 12 transmitted in one frame. Further, the slot allocation unit 10 determines the slot position in the frame allocated to TS1 to TS3. The slot position may be determined in any way.

  FIG. 2 is a diagram illustrating an example of slot positions determined by the slot allocation unit 10. In FIG. 2, numerals represent TS numbers (1 to 3). As shown in FIG. 2, the slot allocation unit 10 includes TS1, TS2, TS2, TS3,..., TS3 from the first data slot to the twelfth data slot, which is the data slot next to the header slot. Determine the slot position to be stored.

  The header generation unit 12 generates a header based on the slot allocation number and the slot number of each TS input from the slot allocation unit 10.

  FIG. 3 is a diagram illustrating an example of a header generated by the header generation unit 12. This header includes packet synchronization information, frame synchronization information, TS_id and original_network_id which are identification information of TS1 to TS15, a relative TS number of a TS stored in each slot, and other information. The packet synchronization information (0x47, number of bits 8) represents the head of data in the TS packet format, and is data for establishing packet synchronization. The frame synchronization information (0x1a86, bit number 16) is data for establishing frame synchronization, that is, data for detecting a header.

  As with Non-Patent Document 1, the slot allocation information is stored in each slot with a maximum of 15 multiplexed TSs, 15 TS identification information (a correspondence table of TS_id and original_network_id and relative TS numbers), and each slot. The TS is composed of a relative TS number (a table in which a relative TS number represented by 4 bits is described for each slot). The TS packet stored in each slot is designated by this slot allocation information.

  In this specific example, as shown in the slot allocation information included in the header of FIG. 3, the TS_id of TS1 is 0x0001, the original_network_id is 0x1001, the TS_id of TS2 is 0x0002, the original_network_id is 0x1001, and the TS_id of TS3 is 0x0003, original0 To do. Further, since the number of TSs to be transmitted is 3, the values of the 4th to 15th TS_id and original_network_id are set to “0xFFFF” as in Non-Patent Document 1.

  As described above, the PCR rewriting units 11-1 to 11-3 determine the number and position of null packets to be inserted by the receiving device 2-1 based on the slot allocation number and slot position of TS1 to TS3, and are included in the TS. Rewrite the PCR value.

  FIG. 4 is a flowchart showing the processing of the PCR rewriting unit 11 (the PCR rewriting units 11-1 and 11-2 are collectively referred to as the PCR rewriting unit 11). Hereinafter, the processing of the PCR rewriting units 11-1 to 11-3 will be described in detail with reference to the flowchart shown in FIG.

  First, the PCR rewriting units 11-1 to 11-3 respectively input TS1 to TS3, the slot allocation number and slot position of the TS (step S401), and correspond to the slot allocation number according to preset correspondence information. The number of slots after adding a null packet is determined (step S402). In this specific example, as correspondence information, it is assumed that the correspondence between the number of assigned slots and the number of slots after adding a null packet is defined.

  FIG. 5 is a diagram for explaining a correspondence example between the number of slot assignments and the number of slots after adding a null packet used in the PCR rewriting units 11-1 to 11-3, and shows correspondence information. The PCR rewriting unit 11-1 uses this correspondence information to determine the number of slots 3 to which the null packet is added, corresponding to the slot allocation number 1 of TS1. Also, the PCR rewriting unit 11-2 uses this correspondence information to determine the number of slots 3 after the addition of the null packet, which corresponds to the slot allocation number 2 of TS2. Also, the PCR rewriting unit 11-3 uses this correspondence information to determine the number of slots 16 after adding a null packet, which corresponds to the slot allocation number 9 of TS3. In the correspondence information shown in FIG. 5, the number of slots after adding a null packet may be defined in any way as long as it is a value equal to or greater than the number of slot allocations.

  In the correspondence information shown in FIG. 5, the slot allocation number corresponds to the TS speed input by the PCR rewriting units 11-1 to 11-3, and the slot number after the addition of the null packet is received as described later. This corresponds to the output speed of the TS output by the device 2-1. That is, this correspondence information defines the correspondence between the TS input speed in the transmission apparatus 1 and the TS output speed in the reception apparatus 2. The PCR rewriting units 11-1 to 11-3 have the TS of the TS1 to TS3 input by the transmission device 1 based on this correspondence information and are equal to or higher than the input TS speed (slot allocation number) and the minimum The speed (number of slots after adding a null packet) is determined as the output speed output by the receiving device 2-1 described later.

  Next, the PCR rewriting units 11-1 to 11-3 change the original TS based on the slot allocation number and slot position of each TS input from the slot allocation unit 10 and the determined number of slots after adding the null packet. The number and position of null packets to be added are determined (steps S403 and S404). The “number and position of null packets added to the original TS” corresponds to the PCR value rewritten to match the TS speed after the addition of the null packet. In this case, the transmission apparatus 1-1 does not actually add a null packet and does not transmit it. This null packet is inserted between TS packets when the requested TS is output in the receiving device 2-1 described later. That is, the PCR value rewritten by the PCR rewriting units 11-1 to 11-3 is consistent with the TS output from the receiving device 2-1.

  The PCR rewriting units 11-1 to 11-3 determine the number of null packets added to the original TS by calculating “number of slots after adding null packets−number of assigned slots” (see FIG. 5). To do. In addition, the PCR rewriting units 11-1 to 11-3 determine the positions of null packets added to the original TS according to preset rule information. This rule information is the same as the rule information used when the separating unit 21 of the receiving device 2-1 described later actually inserts a null packet into the TS. The position of the null packet may be determined in any way as long as it follows the same rule information set in advance in the transmission device 1-1 and the reception device 2-1.

  The PCR rewriting units 11-1 to 11-3 assume, for example, a packet sequence composed of TS packets and added null packets in accordance with preset rule information, and in order from the first packet of the packet sequence, For each TS packet and added null packet, “(number of packets allocated to the packet sequence from the first packet to that point)” / “the number of slots in one frame allocated to the TS (or The number of null packets to be added) ”is calculated. If the calculated result is smaller or the value is the same, the TS packet in the packet sequence and the added null are selected by selecting the TS packet. Determine the order of packets. For example, it is assumed that up to the (x−1) th packet in the packet sequence has been allocated, and a TS packet and a null packet to be added are allocated (that is, a + b = x−1). Here, whether the TS packet or the added null packet is assigned to the x packet is defined as a / A, b /, where A is the number of slots allocated to the TS and B is the number of added null packets. This is done by calculating B. If a / A ≦ b / B, a TS packet is allocated. Otherwise, a null packet is allocated.

  For example, in the case of TS2, the number of slots after the addition of null packets is 3 with respect to the slot allocation number of 2 (see FIG. 5), so the number of added null packets is 3-2 = 1. The position of the null packet to be added is determined by the above-described calculation in order from the first packet in the packet sequence after the null packet is added.

  FIG. 6 is a diagram for explaining a calculation example of the arrangement order of TS packets and added null packets in the case where the number of assigned slots in TS2 is 2 and the number of added null packets is 1. In FIG. 6, the number A of TS packets to be allocated to the packet sequence is 2, and the number B of null packets to be allocated to the packet sequence is 1. For the first packet, since the number a of TS packets distributed to the packet sequence is 0, a / A is 0. On the other hand, since the number b of null packets allocated to the packet sequence is 0, b / B is 0. Therefore, since a / A ≦ b / B, a TS packet is allocated to the first packet. For the second packet, since the number a of TS packets distributed to the packet sequence is 1, a / A is 0.5. On the other hand, since the number b of null packets allocated to the packet sequence is 0, b / B is 0. Accordingly, since a / A ≦ b / B is not satisfied, a null packet is allocated to the second packet. For the third packet, since the number a of TS packets distributed to the packet sequence is 1, a / A is 0.5. On the other hand, since the number b of null packets distributed to the packet sequence is 1, b / B is 1. Therefore, since a / A ≦ b / B, a TS packet is allocated to the third packet.

  Accordingly, the PCR rewriting unit 11-2 performs the calculation shown in FIG. 6 in accordance with the rule information set in advance. For example, in the case of TS2, the null rewriting packet added to the two TS packets that are the original TS2 The position is determined between two TS packets.

  In the rule information described above, an allocation rule is defined so that TS packets are equally spaced in the packet sequence and null packets are equally spaced in the packet sequence. By using this rule information, the receiving device 2-1 described later outputs TSs in which TS packets are arranged at equal intervals in the packet sequence and null packets are arranged at equal intervals in the packet sequence.

  As a result, since TS packets and null packets do not exist in a burst in the TS, when a decoder provided at a later stage of the receiving device 2-1 described later stores the TS packets in a buffer, buffer underflow and buffer overflow Will not occur.

  Returning to FIG. 4, the PCR rewriting units 11-1 to 11-3 indicate the state of the packet sequence after the addition of the null packet (as described above, the transmitting apparatus 1-1 does not insert the null packet, but after the addition of the null packet. Since it is necessary to rewrite the PCR value so as to match the packet sequence of the packet sequence, the state of the packet sequence after the addition of the null packet is assumed (the null packet is inserted by the receiving device 2-1 described later). The PCR value in the TS is rewritten so that the values match (step S405). Specifically, as described in, for example, Patent Document 5, the PCR rewriting units 11-1 to 11-3 position the packet in which the PCR is written in the packet sequence after the addition of the null packet. Calculate the time difference between the state before the addition of the null packet (original state) and the state after the addition of the null packet, and add this time difference to the original PCR value. A value is obtained, and the original PCR value is rewritten to a new PCR value.

  FIG. 7 is a diagram for explaining a relative time interval between the packet sequence after the addition of the null packet and the original TS packet sequence, and shows an example of the above-described TS2. When the original TS packet sequence is TS packet α and TS packet β, the packet sequence after adding the null packet is TS packet α, null packet and TS packet β, and PCR is written in TS packet β To do. In this case, the PCR rewriting unit 11-2 acquires that the packet β in which the PCR is written is located in the third packet in the packet sequence after the addition of the null packet, and the state before the addition of the null packet (the original TS packet) Column, refer to the lower part of FIG. 7) and the state after adding the null packet (packet string after adding the null packet, refer to the upper part of FIG. 7), and calculate the time difference Δ from the original PCR. A new PCR value is obtained by adding the value to the original PCR value, and the original PCR value is rewritten with the new PCR value.

  Returning to FIG. 4, the PCR rewriting units 11-1 to 11-3 output TS1 to TS3 in which the PCR values are rewritten to the multiplexing unit 13 (step S406). As described above, the null packet is not included in TS2 in which the value of PCR is rewritten. The null packet is inserted between TS packets when a receiving apparatus 2-1 described later is requested for the TS.

  The multiplexing unit 13 multiplexes the header and TS1 to TS3 in which the PCR has been rewritten into a predetermined slot position as shown in FIG.

  As described above, according to the transmission device 1-1 of the first embodiment, the PCR rewriting units 11-1 to 11-I are based on the slot allocation number and slot position of each TS determined by the slot allocation unit 10. The number of slots after adding a null packet is determined according to preset correspondence information, the number of slot assignments is subtracted from the number of slots after adding a null packet to determine the number of null packets, and the number of null packets is determined according to preset rule information And the value of PCR is rewritten on the assumption of a packet string after adding a null packet. Here, the null packet is not inserted in the transmission device 1-1 but is inserted in the reception device 2-1. The multiplexing unit 13 multiplexes the TS with the rewritten PCR value into a frame, and transmits the multiplexed frame.

  As a result, the receiving device 2-1 that receives the frame transmitted from the transmitting device 1-1 separates the requested TS from the frame, and rewrites the separated TS in the PCR value in the transmitting device 1-1. By inserting and outputting the same number of null packets determined at the same time in the same position, the TS speed can be increased compared to the case where TS packets other than the requested TS are replaced with null packets in the frame and output. It can be kept low. In addition, when the receiving device 2-1 inserts a null packet into a TS and outputs the TS, the TS speed matches the PCR written in the TS, so there is no need to convert the TS output speed. . Therefore, since it is not necessary to regenerate the clock for conversion, the scale of the clock recovery circuit can be reduced.

[Receiver]
Next, the receiving apparatus according to the first embodiment will be described. FIG. 8 is a block diagram illustrating a configuration of the receiving apparatus according to the first embodiment. The receiving device 2-1 includes a header detection unit 20, a separation unit 21, and a clock reproduction unit 22.

  The receiving device 2-1 receives the frame transmitted by the transmitting device 1-1. This frame is input to the header detection unit 20, the separation unit 21, and the clock reproduction unit 22.

  The header detection unit 20 inputs a frame, detects a header by acquiring a pattern of frame synchronization information (0x1a86) from the header in the frame, and establishes frame synchronization. Specifically, the header detection unit 20 determines the start position of the frame by determining that the frame synchronization information pattern has been received three times in succession at the correct timing. Thereby, frame synchronization is established. Then, the header detection unit 20 acquires the header from the frame, acquires the identification information of each TS and the TS relative number of the TS stored in each slot from the header, and obtains information on the slot allocation number and slot position of each TS. Generate and output to the separation unit 21.

  The separation unit 21 inputs a frame, inputs the number of slot assignments and slot positions of each TS from the header detection unit 20, and inputs the TS output clock from the clock recovery unit 22. Then, the separation unit 21 separates the TS requested by the user from the frame based on the slot allocation number and slot position of each TS, and performs a null packet by the same process as the PCR rewriting unit 11 of the transmission device 1-1. Is added, and TS synchronized with the TS output clock is output. Further, the separation unit 21 determines the speed at which the TS is output based on the number of TS slot assignments, and outputs it to the clock recovery unit 22 as output speed information.

  That is, the separation unit 21 determines the output speed that is equal to or higher than the speed of the TS for the separated TS based on the above-described correspondence information, and outputs the TS at this output speed.

  The clock recovery unit 22 inputs a frame and also receives TS output speed information from the separation unit 21, reproduces a clock synchronized with the transmission speed of the input frame, and divides and multiplies the reproduced clock. Then, a clock defined by the output speed information is generated and output to the separation unit 21 as a TS output clock.

(Concrete example)
Next, specific operations of the respective units in the receiving device 2-1 illustrated in FIG. 8 will be described with specific examples. It is assumed that the frame received by the reception device 2-1 is a frame transmitted by the transmission device 1-1, and the user requests a TS (TS2) with TS_id = 0x0002 and original_network_id = 0x1001.

  FIG. 9 is a flowchart showing the processing of the separation unit 21. First, the separation unit 21 inputs a frame, the slot allocation number and slot position of each TS, and the TS output clock (step S901), and the requested TS2 identification number is obtained from the slot allocation number and slot position of each TS. Based on the requested TS2 slot allocation number and slot position, the requested TS2 is acquired (step S902). Specifically, the separation unit 21 refers to TS identification information (a correspondence table of TS_id and original_network_id and relative TS number) in the header, and TS_id = 0x0002, which matches the requested TS2 identification number, original_network_id = 0x1001 Relative TS number (= 0x2) is identified, and the slot allocation number and slot position of TS2 are acquired from the slot allocation number and slot position of each input TS.

  Next, the separation unit 21 separates the requested TS2 from the frame based on the acquired slot allocation number and slot position (step S903).

  Next, when outputting the TS2 separated from the frame, the separation unit 21 uses preset correspondence information and rule information (used by the transmission device 1-1) for the number and position of null packets added to the TS2. The same information as the corresponding correspondence information and rule information). Note that the separation unit 21 determines the number and position of null packets to be added to the TS 2 by the same processing as the PCR rewriting unit 11 of the transmission device 1-1.

  Specifically, the separation unit 21 determines the number of slots after adding a null packet corresponding to the number of slots allocated to the separated TS2, according to the correspondence information set in advance (step S904). This corresponds to step S402 shown in FIG.

  The separation unit 21 determines the number and position of null packets to be added to the separated TS 2 based on the slot allocation number and slot position, and the determined number of slots after addition of the null packet (steps S905 and S906). . This corresponds to step S403 and step S404 shown in FIG. That is, the separation unit 21 determines the number of null packets to be added to TS2 by the calculation of “number of slots after adding null packets−number of slot assignments” (see FIG. 5). Further, the separation unit 21 determines the position of the null packet to be added to TS2 according to preset rule information (see FIG. 6).

  Next, the separation unit 21 inserts the determined number of null packets into the determined position in TS2 separated from the frame, and outputs the TS2 after the addition of the null packets in synchronization with the TS output clock (step S907). . Specifically, the separation unit 21 inserts one null packet between two TS packets in the frame, and outputs the result as 3 Mbps TS2.

  Further, the separation unit 21 outputs the number of slots after the addition of the null packet for the requested TS2 to the clock recovery unit 22 as output speed information (step S908). In the case of TS2, the output speed information is 3.

  The clock recovery unit 22 recovers a clock synchronized with the frame transmission rate. In this specific example, since the transmission band of the transmission path is 13 Mbps, the clock recovery unit 22 recovers the 13 MHz clock. Then, the clock recovery unit 22 generates a TS output clock from the recovered clock based on the input output speed information, and outputs the TS output clock to the separation unit 21. In the case of TS2, since the input output speed information is 3, the clock recovery unit 22 generates a 3 MHz clock by multiplying the recovered 13 MHz clock by 3/13, and outputs this as a TS output clock.

  As described above, according to the receiving device 2-1 of the first embodiment, the separation unit 21 acquires the slot allocation number and slot position of the TS requested by the user from the slot allocation number and slot position of each TS. The requested TS is separated from the frame, and for the separated TS, the number of slots after adding a null packet is determined according to preset correspondence information, and the number of slots assigned is subtracted from the number of slots after adding the null packet to null. The number of packets is determined, the position of the null packet is determined according to preset rule information, the null packet is inserted into the separated TS, and output in synchronization with the TS output clock. Further, the clock recovery unit 22 generates the TS output clock from the clock synchronized with the frame transmission rate based on the output rate information of the TS after the addition of the null packet output from the separation unit 21.

  In other words, in the first embodiment, the speed of the TS output from the receiving apparatus 2-1 (the number of slots after adding the null packet) is changed according to the original speed input by the transmitting apparatus 1-1 and the slot allocation number and the null packet. It is set in advance according to the correspondence information with the number of slots after addition. Then, the transmission apparatus 1-1 rewrites the PCR value in advance so that it matches when the TS is output at a preset speed. The PCR value rewritten by the transmission device 1-1 corresponds to the number of null packets inserted in the reception device 2-1. That is, the TS after the addition of the null packet output by the receiving device 2-1 includes the PCR rewritten by the transmitting device 1-1, and the speed of the output TS is the PCR included in the TS. Is consistent with the value of.

  In the technique disclosed in Patent Document 5, the receiving device replaces the TS packet other than the requested TS with a null packet and outputs the null packet. On the other hand, in the receiving device 2-1 of the first embodiment, the requested TS is separated from the frame, and only the null packet corresponding to the PCR value rewritten by the transmitting device 1-1 is separated from the separated TS. Since the insertion is performed, the speed of the TS to be output can be suppressed lower than when a TS packet other than the requested TS is replaced with a null packet. Therefore, the power consumption of the entire decoder circuit provided in the subsequent stage of the receiving device 2-1 and the receiving device 2-1 can be reduced as compared with the receiving device disclosed in Patent Document 5.

  Further, since the receiving device 2-1 of the first embodiment does not need to return the output TS speed to the original TS speed, the type of clock to be reproduced is different from that in the case of reproducing the original TS speed. Therefore, the processing of the clock recovery unit 22 can be simplified.

  Further, in the technique of the above-described Patent Document 6, when the factor of the number of slots in one frame is small, the speed of the TS output from the receiving apparatus may increase. On the other hand, in the receiving device 2-1 of the first embodiment, the output TS speed can be reduced regardless of the number of slots in one frame, and the power consumption of the receiving device 2-1 and the decoder as a whole is reduced. Can be reduced.

  Therefore, according to the first embodiment, the receiving device 2-1 separates the requested TS from the frame, and the separated TS has the same number determined at the time of rewriting the PCR value in the transmitting device 1-1. Is inserted at the same position and output. Thereby, the speed of TS can be suppressed low. Therefore, the decoder only has to input and decode a low-speed TS from the receiving device 2-1, so that the processing load can be reduced. Further, since the receiving apparatus 2-1 does not need to return the output TS speed to the original TS speed, the type of clock to be reproduced can be reduced as compared with the case of reproducing the original TS speed. The processing of the playback unit 22 is simplified.

(Modification 1)
In the first embodiment, the PCR rewriting unit 11 of the transmission device 1-1 determines the position of the null packet added to the TS according to preset rule information (FIG. 6). That is, the PCR rewriting unit 11 sets the position of the null packet added to the TS in order from the first packet in the packet sequence to each of the TS packet and the added null packet. Calculate the number of packets allocated to the packet sequence (to the point in time) / “the number of slots in one frame (or the number of added null packets) assigned to the TS”, and the smaller value or value Are determined by selecting a TS packet. On the other hand, in the modification 1, the position of the null packet added to the TS is determined according to other rule information.

  Specifically, the PCR rewriting unit 11 of the transmission device 1-1 receives the TS and also inputs the slot allocation number and slot position of each TS from the slot allocation unit 10, and the number of packets in a preset frame. For a packet of minutes, the number of packets obtained by subtracting the number of slots allocated to the TS from the number of packets is replaced with a null packet. As a result, in the packet sequence including TS packets corresponding to the number of slots allocated and the number of null packets obtained by subtracting the number of slots allocated from the number of slots in the frame, that is, one frame including TS1 to TS3 shown in FIG. A packet string is generated by replacing packets other than the TS with null packets.

  Then, the PCR rewriting unit 11 determines the number of slots after adding the null packet in accordance with the correspondence information shown in FIG. Then, when the number of slots after adding the null packet is not equal to the number of slots in one frame, the PCR rewriting unit 11 (a) the number of null packets to be deleted from the null packet included in the generated packet sequence and Determine the position. Alternatively, (b) the number and position of null packets added to the generated packet sequence are determined. In this way, the PCR rewriting unit 11 determines the number and position of null packets to be deleted or added from the generated packet sequence (a packet sequence in which a packet other than a specific TS is replaced with a null packet in one frame). To do. That is, the PCR rewriting unit 11 determines the number and position of null packets added to the TS.

  Then, the PCR rewriting unit 11 rewrites the PCR value in the TS so that the PCR value matches in the state of the packet string after the addition of the null packet.

  Hereinafter, cases (a) and (b) will be described. First, (a) a case where the number and position of null packets to be deleted are determined from null packets included in the generated packet sequence will be described. In this case, the speed of the TS output by the reception device 2-1 is a speed less than the transmission band of the transmission path. This is because the number of slots after adding a null packet is less than the number of slots in one frame. The PCR rewriting unit 11 determines the position of the null packet to be deleted in the packet string excluding the packet of a specific TS in the frame, floor {k × (number of slots in one frame−number of TS slots allocated) / (deletion). Number of null packets)} function. k is an integer that increases by 1 from 1 to “the number of null packets to be deleted”. The floor function floor {c} represents a maximum integer equal to or smaller than c.

  A specific example will be described. For example, in the case of TS2, the number of slot assignments is 2, and the number of slots after adding a null packet is 3. Therefore, when a packet other than TS2 in the frame is a null packet, the number of null packets is 13-2 = 11. The number of null packets deleted from among them is 13−3 = 10. Therefore, the PCR rewriting unit 11-2 first generates a packet sequence of only 11 null packets, and determines the positions of 10 null packets to be deleted using the floor function floor. .

  FIG. 10 is a diagram illustrating a packet sequence composed of null packets when a TS2 packet is removed from one frame, and FIG. 11 is a diagram illustrating an example of calculating the position of a null packet to be deleted. The PCR rewriting unit 11-2 generates a packet sequence of only 11 null packets shown in FIG. 10, and from among them, as shown in FIG. , 11). In FIG. 11, the position of the null packet to be deleted is calculated by a floor function in which k is increased from 1 by 1.

  FIG. 12 is a diagram showing the positions of null packets to be deleted in a packet sequence composed of null packets when TS2 packets are removed from one frame, and FIG. 13 replaces packets other than TS2 with null packets. It is a figure which shows the position of the null packet deleted in a packet sequence. The PCR rewriting unit 11-2 determines the positions of the null packets to be deleted as the first to ninth and eleventh positions as shown in FIG. 12 by the calculation shown in FIG. In this way, as shown in FIG. 13, the PCR rewriting unit 11-2 determines the number and position of null packets to be deleted in the generated packet sequence (a packet sequence in which packets other than TS2 are replaced with null packets). Then, the number and position indicated by N of the blacked portions are determined. In FIG. 12 and FIG. 13, the location of the null packet to be deleted is shown in black.

  Then, the PCR rewriting unit 11-2 rewrites the PCR value in TS2 so that the PCR value matches in the state of the packet string after the addition of the null packet.

  FIG. 14 is a diagram for explaining a relative time interval between the packet sequence after null packet deletion and the original TS packet sequence in TS2. When the original TS packet sequence is TS packet α and TS packet β, the packet sequence after null packet deletion is TS packet α, TS packet β, and null packet, and PCR is written in TS packet β To do. In this case, the PCR rewriting unit 11-2 acquires that the packet β in which the PCR is written is located in the second packet in the packet sequence after the null packet deletion, and the state before the null packet deletion (original TS packet) Column, see the lower part of FIG. 14) and the state after null packet deletion (the packet string after null packet deletion, see the upper part of FIG. 14), and calculate this time difference Δ from the original PCR Then, a new PCR value is obtained by subtracting from the previous value, and the original PCR value is rewritten to the new PCR value.

  Next, (b) the case where the number and position of null packets added to the generated packet sequence are determined will be described. In this case, the speed of the TS output by the receiving device 2-1 is larger than the transmission band of the transmission path. This is because the number of slots after adding a null packet becomes larger than the number of slots in one frame. In addition, the receiving device 2-1 replaces a slot to which a slot other than the TS for which the PCR is to be rewritten is assigned with a null packet, and adds a null packet to the packet sequence generated thereby, and outputs it. . Therefore, the PCR rewriting unit 11 sets the position of the added null packet to “the packet in the frame” and “the added null packet”. "Number" / "number of packets to be allocated to the packet sequence" is calculated, and if the smaller one or the same value is selected, it is determined by selecting "packets in frame".

  A specific example will be described. For example, in the case of TS3, the slot allocation number is nine. The number of slots after adding a null packet is 16, which is larger than the number of slots (13) in one frame. Therefore, the PCR rewriting unit 11-3 determines the positions of three new null packets to be newly added as follows for the packet sequence generated by replacing packets other than TS3 in the frame with null packets.

  FIG. 15 is a diagram illustrating a packet sequence in which packets other than TS3 are replaced with null packets. As illustrated in FIG. 15, the PCR rewriting unit 11-3 generates a packet sequence in which packets other than TS3 are replaced with null packets in one frame including TS1 to TS3 illustrated in FIG.

  The PCR rewriting unit 11-3 assumes a packet sequence composed of 16 packets obtained by adding 3 null packets to this packet sequence, and 1 packet of the assumed packet sequence according to preset rule information For each of the first through sixteenth packets, the same processing as in FIG. 6 is performed to determine the arrangement order of the TS packets in the packet sequence and the added null packets.

  FIG. 16 is a diagram for explaining a calculation example of the arrangement order of packets in a frame and added null packets. FIG. 17 shows that a null packet is added to a packet sequence in which packets other than TS3 are replaced with null packets. It is a figure which shows an example. The PCR rewriting unit 11-3 performs the calculation shown in FIG. 16 according to preset rule information, and determines the positions of the three added null packets at the second packet, the seventh packet, and the twelfth packet. . In this way, as shown in FIG. 17, the PCR rewriting unit 11-3 determines the number and position of added null packets in the generated packet sequence (a packet sequence in which packets other than TS3 are replaced with null packets). Then, the number and position indicated by N of the black portions are determined. In FIG. 17, the portion of the added null packet is shown in black.

  Then, the PCR rewriting unit 11-3 rewrites the PCR value in TS3 so that the PCR value matches in the state of the packet string after the addition of the null packet.

  On the other hand, the separating unit 21 of the receiving device 2-1 performs the same process as the PCR rewriting unit 11 of the transmitting device 1-1 to determine the number and position of null packets to be added. That is, the separation unit 21 generates a packet sequence in which a packet other than the TS requested by the user is replaced with a null packet in the frame, and determines the number of slots after adding the null packet according to the correspondence information shown in FIG. The number of null packets added to the TS is determined. When the number of slots after adding the null packet is not equal to the number of slots in one frame, the separation unit 21 (a) determines the number and position of null packets to be deleted from the null packets included in the generated packet sequence. decide. Alternatively, (b) the number and position of null packets to be added to the generated packet sequence are determined. And the separation part 21 produces | generates and outputs TS after the null packet addition assumed in the transmitter 1-1 by deleting or adding a null packet.

  As described above, according to the first modification of the first embodiment, the same effects as those of the first embodiment described above can be obtained. In addition, when the speed of the TS output by the receiving device 2-1 is equal to the transmission speed of the frame (that is, the number of slots after adding the null packet is equal to the number of slots of one frame, Although not shown, when the number of slots after adding a null packet is defined as 13), as in the technique described in Patent Document 5, the separation unit 21 of the reception device 2-1 A TS can be output simply by replacing a packet other than the requested TS with a null packet. Thereby, processing becomes simple.

(Modification 2)
In the first embodiment, the PCR rewriting unit 11 of the transmission device 1-1 determines the number of slots after adding a null packet in accordance with preset correspondence information (FIG. 5). On the other hand, in the second modification, the number of slots after adding a null packet is determined according to other correspondence information. The number of slots after the addition of a null packet included in the other correspondence information in Modification 2 is a predetermined positive integer and a factor of the predetermined positive integer.

  FIG. 18 is a diagram for explaining a correspondence example between the number of assigned slots and the number of slots after adding a null packet. As shown in FIG. 18, the correspondence information defines that the number of slots after adding a null packet is 16 and its factor, for example.

  As described above, according to the second modification of the first embodiment, the same effects as those of the first embodiment described above can be obtained. Further, the clock necessary for the clock recovery unit 22 of the receiving device 2-1 is only a certain frequency and a factor thereof, that is, a frequency divided by an integer. Therefore, if a certain frequency is reproduced, all necessary clocks can be reproduced only by frequency division, and the circuit scale of the clock reproduction unit 22 can be remarkably reduced. For example, when the correspondence information shown in FIG. 18 is followed, the clock recovery unit 22 may generate a 16 MHz clock by multiplying the 13 MHz clock recovered from the 13 Mbps speed by 16/13. As a result, the clock recovery unit 22 generates all TS output clocks with only a simple circuit that divides this by an integer (1/2, 1/4, 1/8, 1/16). Thus, the scale of the clock recovery unit 22 can be further reduced.

  Next, Example 2 will be described. The second embodiment is an example of a system that transmits a plurality of TSs using a plurality of channels. In the following, description will be given separately for a transmitting device and a receiving device.

[Transmitter]
First, the transmission apparatus according to the second embodiment will be described. Comparing the transmission apparatus 1-1 according to the first embodiment with the transmission apparatus according to the second embodiment, the transmission apparatus 1-1 according to the first embodiment has one channel for transmitting a frame, whereas the transmission apparatus 1-1 according to the first embodiment has a single channel. The transmitting apparatus is different in that the number of channels is J (J is an integer of 2 or more).

  FIG. 19 is a block diagram illustrating a configuration of the transmission apparatus according to the second embodiment. The transmission device 1-2 includes a slot allocation unit 10, PCR rewriting units 11-1 to 11-I, a header generation unit 12, and a multiplexing unit 13.

  The transmission apparatus 1-2 inputs I TS1 to TSI to be transmitted, and acquires speed information 1 to I indicating the speed of each input TS. Note that I TS1 to TSI input by the transmitting device 1-2 are speed-converted in advance so that each TS is assigned to each data slot of J frames in a slot assignment unit 10 described later. It is assumed that the PCR value is also rewritten.

  The slot allocation unit 10 receives the speed information 1 to I, determines the number of slots and the slot position of each TS in J frames to be allocated to each TS, and converts these information into the PCR rewriting units 11-1 to 11-1. 11-I, output to the header generation unit 12 and the multiplexing unit 13.

  The PCR rewriting units 11-1 to 11-I input TS1 to TSI, and also input the slot allocation number and slot position of each TS in the J frames from the slot allocation unit 10, and for TS1 to TSI, Based on the slot allocation number and slot position in J frames, the number and position of null packets to be inserted into a TS to be combined by the receiving apparatus 2-2 described later are determined. Similar to the first embodiment, the null packet is inserted when the receiving device 2-2 separates and combines the requested TS from the J frames and outputs it. Then, the PCR rewriting units 11-1 to 11-I rewrite the PCR values written in each TS based on the number and position of null packets inserted by the receiving device 2-2, and rewrite the PCR values. TS1 to TSI are output to the multiplexing unit 13.

  The header generation unit 12 inputs the slot allocation number and slot position of each TS in the J frames from the slot allocation unit 10, and identifies TS identification information (TS_id (TS identifier) and original_network_id (original network identifier)) and relative TS. (Number correspondence table) and J headers including slot allocation information composed of relative TS numbers of TS stored in each slot are generated, and the generated J headers are output to the multiplexing unit 13.

  The multiplexing unit 13 receives the TS1 to TSI in which the PCR values are rewritten from the PCR rewriting units 11-1 to 11-I, and the slot allocation number and slot of each TS in the J frames from the slot allocation unit 10. The position is input, and J headers are input from the header generation unit 12. Then, the multiplexing unit 13 divides the input TS1 to TSI in accordance with preset division rule information, and inputs the input J headers and the divided TS1 to TSI to each TS in the input J frames. Are multiplexed into J frames based on the slot allocation number and the slot position, and the multiplexed J frames are transmitted to the receiving device 2-2 described later.

(Concrete example)
Next, specific operations of each unit in the transmission device 1-2 illustrated in FIG. 19 will be described with specific examples. The TS input to the transmission device 1-2 is three (I = 3), and the speed of each TS is TS1 = 58Mbps, TS2 = 23Mbps, TS3 = 3Mbps, and one channel has a transmission bandwidth of 13Mbps. To do. The number of channels is 7 (J = 7), and the frame is composed of one header slot and 12 data slots.

  In this specific example, the data transmission rate when using one slot is 13 Mbps / 13 slots = 1 Mbps, and the data transmission rate when using all seven channels is 13 Mbps × 7 = 91 Mbps. The total speed of all TSs is 84 Mbps, and all TSs can be transmitted in a total of 84 slots.

  The slot allocation unit 10 receives the speed information 1 to 3 of TS1 to TS3, and determines the number of slots for each of the channels 1 to 7 to be allocated to TS1 to TS3 based on the speed information 1 to 3. In this specific example, 12 slots of channels 1 to 4 and 10 slots of channel 5 are determined for TS1, that is, 58 slots in total. For TS2, 2 slots of channel 5, 12 slots of channel 6, and 9 slots of channel 7, that is, 23 slots in total are determined. Also, 3 slots of channel 7 are determined for TS3.

  Further, the slot allocation unit 10 determines the slot positions in the seven frames allocated to TS1 to TS3. The slot position may be determined in any way as long as the determined number of slots is satisfied.

  FIG. 20 is a diagram illustrating an example of slot positions determined by the slot allocation unit 10. In FIG. 20, numerals represent TS numbers (1 to 3). As shown in FIG. 20, the slot assignment unit 10 determines the slot positions of the channels 1 to 7 to be assigned to TS1 to TS3.

  The header generation unit 12 generates headers 1 to 7 based on the slot allocation number and the slot number (see FIG. 20) of each TS in the seven frames input from the slot allocation unit 10.

  FIG. 21 is a diagram illustrating an example of headers 1 to 7 generated by the header generation unit 12. Similar to the header shown in FIG. 3, the headers 1 to 7 are packet synchronization information, frame synchronization information, TS_id and original_network_id which are identification information of TS1 to TS15, the relative TS number of the TS stored in each slot, and Consists of other information. Description of each information is omitted.

  As described above, the PCR rewriting units 11-1 to 11-3 determine the number and position of null packets to be inserted by the receiving device 2-2 based on the slot allocation number and slot position of TS1 to TS3 in J frames. Determine and rewrite TS PCR. Hereinafter, the processing of the PCR rewriting units 11-1 to 11-3 will be described in detail. Basically, the processing is the same as that shown in FIG.

  First, the PCR rewriting units 11-1 to 11-3 respectively input the slot assignment numbers and slot positions of TS1 to TS3 and TS1 to TS3 in J frames, and the slot assignment numbers according to preset correspondence information. The number of slots after the addition of null packets corresponding to the total is determined.

  FIG. 22 is a diagram for explaining a correspondence example between the total number of slot assignments used in the PCR rewriting units 11-1 to 11-3 and the number of slots after adding a null packet. Using this correspondence information, the PCR rewriting unit 11-1 determines the number of slots 60 after the addition of null packets, which corresponds to the total number 58 of TS1 slot assignments. Also, the PCR rewriting unit 11-2 uses this correspondence information to determine the number of slots 40 after adding null packets, which corresponds to the total number 23 of slots allocated to TS2. Also, the PCR rewriting unit 11-3 uses this correspondence information to determine the number of slots 20 after adding null packets, which corresponds to a total of 3 slot allocation numbers of TS3. In the correspondence information shown in FIG. 22, the number of slots after the addition of the null packet may be defined in any way as long as it is larger than the total number of slot allocations.

  Next, the PCR rewriting units 11-1 to 11-3 set the slot allocation numbers and slot positions of TS1 to TS3 in the J frames input from the slot allocation unit 10 and the determined number of slots after adding the null packet. Based on this, the number and position of null packets added to the original TS are determined. The “number and position of null packets added to the original TS” corresponds to the PCR value rewritten to match the TS speed after the addition of the null packet. In this case, the transmitter 1-2 does not actually add a null packet and does not transmit it. This null packet is inserted between TS packets when the requested TS is output in the receiving device 2-2 described later. That is, the PCR value rewritten by the PCR rewriting units 11-1 to 11-3 is consistent with the TS output from the receiving device 2-2.

  The PCR rewriting units 11-1 to 11-3 calculate the number of null packets added to the original TS as “the total number of slots after the addition of null packets−slot allocation number” (see FIG. 22). Determined by. In addition, the PCR rewriting units 11-1 to 11-3 determine the positions of null packets added to the original TS according to preset rule information. This rule information is the same as the rule information used when the separating unit 21 of the receiving device 2-2 described later actually inserts a null packet into the TS. Note that the position of the null packet may be determined in any way as long as it conforms to the same rule information set in advance in the transmission device 2-2 and the reception device 2-2.

  For example, as in the first embodiment, the PCR rewriting units 11-1 to 11-3 assume a packet sequence composed of TS packets and added null packets, and in order from the first packet of the packet sequence, TS packets For each of the added null packets, “(number of packets allocated to the packet sequence from the first packet to that point in time)” / “number of slots in one frame allocated to the TS (or added) Number of null packets)), and if the calculated result is smaller or the value is the same, select the TS packet to select the TS packet in the packet string and the added null packet. Determine the order. Details of the processing are the same as those in the first embodiment, and a description thereof will be omitted.

  Next, the PCR rewriting units 11-1 to 11-3 rewrite the PCR values in the TS so that the PCR values match in the state of the packet string after the addition of the null packet. Details of the processing are the same as those in the first embodiment, and a description thereof will be omitted.

  The multiplexing unit 13 divides the TS1 to TS3 in which the PCR value is rewritten into the same number of data strings as the number of channels 7 to be transmitted, according to preset division rule information. The division rule information may be any rule.

  FIG. 23 is a diagram for explaining TS division processing (processing for TS1) by the multiplexing unit 13, and FIG. 24 is a diagram for explaining TS division processing (processing for TS2) by the multiplexing unit 13. In the present embodiment, the multiplexing unit 13 divides the TS according to the rule of allocating one packet at a time in ascending order of channel number and slot number according to the assigned slot position for the input TS. 23 and 24, the numbers indicate the order of TS packets.

  Then, the multiplexing unit 13 multiplexes the divided TS and J headers based on the slot allocation numbers and slot positions of TS1 to TS3 in the input J frames, and generates the seven frames shown in FIG. Send.

  As described above, according to the transmission device 1-2 of the second embodiment, the PCR rewriting units 11-1 to 11-I have the number of slot allocations of each TS in the J frames determined by the slot allocation unit 10. And determining the number of slots after adding a null packet based on the preset correspondence information, subtracting the total number of assigned slots from the number of slots after adding the null packet, and determining the number of null packets. The position of the null packet is determined according to the set rule information, and the PCR value is rewritten assuming the packet string after the addition of the null packet. Here, the null packet is not inserted in the transmission device 1-2, but is inserted in the reception device 2-2. Then, the multiplexing unit 13 multiplexes the TS with the rewritten PCR value into J frames, and transmits the multiplexed J frames.

  Thus, the receiving device 2-2 that receives the J frames transmitted from the transmitting device 1-2 separates the requested TS from the frame, combines the separated TSs, and the transmitting device 1-2 performs PCR. By inserting and outputting the same number of null packets determined at the time of rewriting the value at the same position, TS packets other than the requested TS are replaced with null packets and output in J frames. Compared to the case, the TS speed can be kept low. In addition, since the receiving device 2-2 does not need to return the output TS speed to the original TS speed, the type of clock to be reproduced can be reduced compared with the case of reproducing the original TS speed. The processing of the playback unit 22 is simplified.

[Receiver]
Next, a receiving apparatus according to the second embodiment will be described. Comparing the receiving apparatus 2-1 of the first embodiment with the receiving apparatus of the second embodiment, the receiving apparatus 2-1 of the first embodiment includes one header detection unit 20, whereas the second embodiment The receiving apparatus is different in that it includes J header detection units 20 corresponding to the number of frames.

  FIG. 25 is a block diagram illustrating a configuration of the receiving apparatus according to the second embodiment. The receiving device 2-2 includes header detection units 20-1 to 20-J, a separation unit 21, and a clock recovery unit 22.

  The receiving device 2-2 receives J frames transmitted by the transmitting device 1-2. Individual frames 1 to J among the J frames are input to the header detectors 20-1 to 20-J, respectively. The J frames are input to the separation unit 21 and the clock recovery unit 22.

  The header detection units 20-1 to 20-J receive the frames 1 to J, respectively, detect the header by obtaining the pattern of the frame synchronization information (0x1a86) from the headers in the frames 1 to J, and perform frame synchronization. Establish. The process for establishing frame synchronization is the same as in the first embodiment. Then, the header detection units 20-1 to 20-J respectively obtain the header from the frames 1 to J, obtain the identification information of each TS and the relative TS number of the TS stored in each slot from the header, and each TS The number of assigned slots and the information on the slot position are generated and output to the separation unit 21.

  The separation unit 21 inputs J frames, inputs the slot allocation number and slot position of each TS in the J frames from the header detection units 20-1 to 20 -J, and receives the TS from the clock recovery unit 22. Input the output clock. Then, the separation unit 21 separates the TS requested by the user from the J frames based on the slot allocation number and the slot position of each TS, and sets the division rule information set in advance (the transmission device 1-2). According to the same information as the division rule information used in the multiplexing unit 13, the separated TS packet sequence is combined into one TS. Then, the separation unit 21 adds a null packet to the synthesized TS by the same process as the PCR rewriting unit 11 of the transmission device 1-2, and outputs a TS synchronized with the TS output clock. In addition, the separation unit 21 determines a speed at which the TS is output based on the number of slot assignments of the combined TS, and outputs the TS to the clock recovery unit 22 as output speed information.

  The clock recovery unit 22 inputs J frames and also receives TS output speed information from the separation unit 21, recovers a clock synchronized with the input frame transmission speed, and divides and multiplies the recovered clock. As a result, a clock defined by the output speed information is generated and output to the separation unit 21 as a TS output clock.

(Concrete example)
Next, specific operations of each unit in the receiving device 2-2 illustrated in FIG. 25 will be described with specific examples. The seven frames received by the receiving device 2-2 are the seven frames transmitted by the transmitting device 1-2, and the user requests a TS (TS2) with TS_id = 0x0002 and original_network_id = 0x1001. And The processing of the dividing unit 21 is basically the same as the processing shown in FIG.

  First, the separation unit 21 receives 7 frames, the slot allocation numbers and slot positions of TS1 to TS3 in the 7 frames, and the TS output clock, and the slot allocation numbers of TS1 to TS3 in the 7 frames. And the requested slot allocation number and slot position of TS2 are obtained from the slot position.

  Next, the separating unit 21 separates the requested TS2 from the frame based on the acquired slot allocation number and slot position of TS2, and combines them into one TS2 according to preset division rule information. In this specific example, as shown in FIG. 23 and FIG. 24, the channel number and the slot number are lower from the plurality of frames to which the TS is assigned (refer to FIG. 24, frames 2 and 3 in the case of TS2). In order, they are read out and synthesized one by one.

  Next, when outputting the combined TS2, the separating unit 21 sets the number and position of null packets to be added to the TS2 in accordance with preset correspondence information and rule information (correspondence used in the transmission device 1-2). Information and the same information as rule information). Note that the separation unit 21 determines the number and position of null packets to be added to the TS by the same processing as the PCR rewriting unit 11 of the transmission device 1-2.

  Specifically, the separation unit 21 determines the number of slots after adding null packets corresponding to the total number of slots allocated to TS2 in accordance with correspondence information set in advance. Then, the separation unit 21 determines the number and position of null packets to be added to the combined TS 2 based on the slot allocation number and slot position of TS 2 and the determined number of slots after addition of the null packet. That is, the separation unit 21 determines the number of null packets to be added to TS2 by calculating “the number of slots after the addition of null packets−the total number of slot assignments” (see FIG. 22). The position of the null packet to be added is determined according to preset rule information (see FIG. 6).

  Next, the separation unit 21 inserts the determined number of null packets into the determined position in the combined TS2, and outputs the TS2 after the addition of the null packet in synchronization with the TS output clock. Thereby, TS2 is output from the receiving apparatus 2-2 at a speed higher than the original speed input by the transmitting apparatus 1-2. In the case of TS2, 17 null packets are added to 23 TS packets and output as a 40 Mbps TS.

  Further, the separation unit 21 outputs the number of slots after the addition of the null packet for the requested TS2 to the clock recovery unit 22 as output speed information. The output speed information of TS2 is 40.

  The clock recovery unit 22 recovers a clock synchronized with the transmission speed per channel. In this specific example, since the transmission band of the transmission path per channel is 13 Mbps, the clock recovery unit 22 recovers the 13 MHz clock. Then, the clock recovery unit 22 generates a TS output clock from the recovered clock based on the input output speed information, and outputs the TS output clock to the separation unit 21. In the case of TS2, since the input output speed information is 40, the clock recovery unit 22 generates a 40 MHz clock by multiplying the recovered 13 MHz clock by 40/13, and outputs this as a TS output clock.

  As described above, according to the receiving device 2-2 of the second embodiment, the separation unit 21 determines the number of TS slot allocation requested by the user from the slot allocation number and slot position of each TS in J frames. And the slot position is obtained, the requested TS is separated from each frame, the separated TSs are combined, and the number of slots after adding a null packet is determined for the combined TS in accordance with preset correspondence information, Determine the number of null packets by subtracting the number of slot assignments from the number of slots after the addition of null packets, determine the position of the null packet according to preset rule information, insert the null packet into the synthesized TS, and output the TS output clock Output in sync with. Further, the clock recovery unit 22 generates the TS output clock from the clock synchronized with the transmission rate per channel based on the output rate information of the TS after the null packet addition output from the separation unit 21.

  In other words, in the second embodiment, the rate of TS output from the receiving device 2-2 (the number of slots after addition of a null packet) is changed according to the original rate input by the transmitting device 1-2 and the number of slot allocations and null packets. It is set in advance according to the correspondence information with the number of slots after addition. Then, the transmission device 1-2 rewrites the PCR value in advance so that it matches when the TS is output at a preset speed. The PCR value rewritten by the transmission device 1-2 corresponds to the number of null packets inserted in the reception device 2-2. That is, the TS after the addition of the null packet output by the receiving device 2-2 includes the PCR rewritten by the transmitting device 1-2, and the speed of the output TS is the PCR included in the TS. Is consistent with the value of.

  Further, in the second method described in Patent Document 4 described above, the receiving apparatus outputs TS at a speed N times the transmission speed per channel (N is the number of channels). On the other hand, in the receiving device 2-2 of the second embodiment, the number of null packets corresponding to the number of slot assignments is inserted, and the TS is output at a speed after the null packet is added. That is, since the receiving apparatus 2-2 outputs TS at a speed lower than N times the transmission speed per channel, the TS speed can be kept low. Therefore, the power consumption of the entire decoder circuit provided at the subsequent stage of the receiving device 2-2 and the receiving device 2-2 can be reduced as compared with the receiving device of Patent Document 4.

  In the first method described in Patent Document 4 described above, the clock recovery circuit of the receiving apparatus needs to generate N types of clocks (N is the number of channels) at the maximum. On the other hand, in the receiving device 2-2 of the second embodiment, a clock synchronized with the transmission speed per channel is reproduced, and a TS output clock is generated from the reproduced clock based on the input output speed information. That is, the receiving device 2-2 only needs to generate a smaller number of clocks than the clock generated by the receiving device of Patent Document 4, and thus the processing of the clock recovery unit 22 is simplified.

  Therefore, according to the second embodiment, the receiving device 2-2 separates the requested TS from the J frames, combines the separated TS, and rewrites the PCR value in the transmitting device 1-2. The determined number of null packets are inserted at the same position and output. Thereby, the speed of TS can be suppressed low. Therefore, the decoder only has to input a low-speed TS from the receiving device 2-2 and decode it, so that the processing load can be reduced. Further, when the receiving device 2-2 inserts a null packet into a TS and outputs the TS, the TS matches the PCR written in the TS, and the receiving device 2-2 inserts a null packet. What is necessary is just to generate | occur | produce the clock corresponding to the speed | rate of TS to output from the clock synchronized with the transmission speed per channel. Therefore, the scale of the clock recovery unit 22 can be reduced.

(Modification 1)
In the second embodiment, the PCR rewriting unit 11 of the transmission device 1-2 determines the number of slots after adding a null packet according to preset correspondence information (FIG. 22). On the other hand, in the first modification, the number of slots after adding a null packet is determined according to other correspondence information. The number of slots of the null packet included in the other correspondence information in the first modification is set to a predetermined positive integer and a factor of the predetermined positive integer, as in the second modification of the first embodiment.

  FIG. 26 is a diagram for explaining a correspondence example between the total number of assigned slots and the number of slots after adding a null packet. As shown in FIG. 26, the correspondence information defines, for example, that the number of slots after adding a null packet is 96 and its factor.

  As described above, according to the first modification of the second embodiment, the same effects as those of the second embodiment described above can be obtained. Further, the clock required by the clock recovery unit 22 of the receiving device 2-2 is only a certain frequency and a factor thereof, that is, a frequency divided by an integer. Therefore, if a certain frequency is reproduced, all necessary clocks can be reproduced only by frequency division, and the circuit scale of the clock reproduction unit 22 can be remarkably reduced. For example, according to the correspondence information shown in FIG. 26, the clock recovery unit 22 may generate a 16 MHz clock by multiplying the 13 MHz clock recovered from the 13 Mbps speed by 96/13. As a result, the clock recovery unit 22 converts this to 1 / integer (1/2, 1/3, 1/4, 1/6, 1/8, 1/12, 1/16, 1/24, 1 / 32, 1/48, 1/96), it is possible to generate all TS output clocks with only a simple circuit, and the scale of the clock recovery unit 22 can be further reduced.

(Modification 2)
In the second embodiment and the first modification of the second embodiment, in the correspondence information (FIGS. 22 and 26) used when the PCR rewriting unit 11 of the transmission device 1-2 determines the number of slots after adding the null packet, The number of slots after adding a packet is defined in units of one slot. On the other hand, in the second modification, the number of slots after adding a null packet in the correspondence information is defined in units of the number of slots in one frame. Moreover, in the modification 2, the position of the null packet added with respect to TS is determined according to other rule information.

  Specifically, the PCR rewriting unit 11 of the transmission device 1-2 receives the TS, inputs the number of slot assignments and the slot position of each TS from the slot assignment unit 10, and transmits a specific TS. A packet other than a specific TS in a frame (Z is an integer of 1 or more) is replaced with a null packet. When Z is 2 or more, they are combined into one packet sequence according to preset division rule information.

  Then, the PCR rewriting unit 11 determines the number of slots after adding the null packet according to the correspondence information set in advance, and determines the number of null packets added to the TS. When the number of slots after adding the null packet and the value obtained by multiplying the number of slots of one frame by Z are not equal, the PCR rewriting unit 11 deletes (a) the null packet included in the generated packet sequence. Determine the number and location of null packets to be played. Alternatively, (b) the number and position of null packets added to the generated packet sequence are determined.

  As described above, according to the second modification of the second embodiment, the same effects as those of the second embodiment described above can be obtained. Further, when the number of slots after adding a null packet of a certain TS is equal to the value obtained by multiplying the number of slots of one frame by Z, separation of the receiving device 2-2 is performed as in the first modification of the first embodiment. After replacing a packet other than the requested TS in Z frames with a null packet, the unit 21 combines the packet sequence with the TS according to preset division rule information when Z is 2 or more. As a result, TS can be output, and the processing becomes simple.

(Modification 3)
In Modification 3, the number of slots after adding a null packet in the correspondence information is obtained by multiplying the number of slots in one frame by a predetermined positive integer and the number of slots in one frame by the factor of the predetermined positive integer. It is specified as the value.

  As described above, according to the third modification of the second embodiment, the same effects as those of the second embodiment and the second modification of the second embodiment are obtained. Further, the clock required by the clock recovery unit 22 of the receiving device 2-2 is only a certain frequency and a factor thereof, that is, a frequency divided by an integer. Therefore, if a certain frequency is reproduced, it is possible to reproduce all necessary clocks only by frequency division. Similarly to the second modification of the first embodiment and the first modification of the second embodiment, the clock reproduction section 22 The circuit scale can be significantly reduced.

  Note that a normal computer can be used as the hardware configuration of the transmission apparatuses 1-1 and 1-2 and the reception apparatuses 2-1 and 2-2 according to the first and second embodiments of the present invention. The transmission devices 1-1 and 1-2 and the reception devices 2-1 and 2-2 are configured by a computer having a volatile storage medium such as a CPU and a RAM, a non-volatile storage medium such as a ROM, and an interface. Is done. The functions of the slot allocation unit 10, the PCR rewriting unit 11, the header generation unit 12, and the multiplexing unit 13 provided in the transmission apparatuses 1-1 and 1-2 are executed by causing the CPU to execute a program describing these functions. Each is realized. The functions of the header detection unit 20, the separation unit 21, and the clock recovery unit 22 included in the reception devices 2-1 and 2-2 are realized by causing the CPU to execute a program describing these functions. . These programs can be stored and distributed in a storage medium such as a magnetic disk (floppy (registered trademark) disk, hard disk, etc.), optical disk (CD-ROM, DVD, etc.), semiconductor memory, or the like.

DESCRIPTION OF SYMBOLS 1 Transmission apparatus 2 Reception apparatus 10 Slot allocation part 11 PCR rewriting part 12 Header generation part 13 Multiplexing part 20 Header detection part 21 Separation part 22 Clock reproduction part

Claims (12)

In a transmission device for inputting a plurality of digital data, time division multiplexing the plurality of digital data in units of packets, forming a frame consisting of a header slot and a data slot, and transmitting to a transmission path using a predetermined number of channels,
A slot allocation unit for determining a slot allocation number and a slot position for each digital data when storing the plurality of digital data in a data slot in the frame;
A header generation unit that generates a header based on the slot allocation number and the slot position determined by the slot allocation unit;
A PCR rewriting unit for rewriting a value of a PCR (program clock reference) included in the digital data;
The header generated by the header generation unit is stored in a header slot in the frame, and the PCR values are rewritten based on the slot allocation number and slot position determined by the slot allocation unit. A multiplexing unit that stores data in a data slot in the frame and multiplexes to form a frame, and
The PCR rewriting unit
A plurality of rates in units of a transmission rate per slot or a transmission rate per channel is defined in advance as correspondence information corresponding to an input rate of digital data input by the transmission device , and constitutes one frame Based on the correspondence information including an arbitrary speed unrelated to the speed according to the number, the minimum speed that is equal to or higher than the input speed of the digital data input by the transmitting device among the plurality of speeds Is the output speed of the digital data output by the receiving apparatus that receives the frame, and the PCR value is rewritten so as to match the output speed. The transmission apparatus according to claim 1,
The plurality of rates included in the correspondence information provided in the PCR rewriting unit is obtained by multiplying the transmission rate per slot by a predetermined positive integer, and according to the number of slots constituting the one frame. A transmission apparatus characterized by an arbitrary value unrelated to the speed and a value obtained by multiplying the transmission speed per slot by the factor of the predetermined positive integer. The transmission apparatus according to claim 1,
The plurality of rates included in the correspondence information provided in the PCR rewriting unit is obtained by multiplying the transmission rate per channel by a predetermined positive integer, and according to the number of slots constituting the one frame. An arbitrary value unrelated to the speed and a value obtained by multiplying the transmission speed per channel by the predetermined positive integer factor. The transmission apparatus according to claim 1,
The PCR rewriting unit
The slot assignment determined by the slot assignment unit assuming that the digital data after the addition of a null packet to the digital data input by the transmission apparatus is digital data output at the output speed by the reception apparatus that receives the frame The number and position of null packets added to the digital data are determined based on the number, and the PCR value is rewritten to match the speed of the digital data after the addition of the null packets. Transmitter device. The transmission device according to claim 4, wherein
The PCR rewriting unit
The correspondence information includes correspondence information in which the number of slot assignments and the number of slots after adding a null packet are defined correspondingly, and based on the number of slot assignments determined by the slot assignment unit according to the correspondence information, A transmission apparatus characterized by determining the number of null packets. The transmission device according to claim 4 or 5,
The PCR rewriting unit
Rule data for allocating original digital data data packets and null packets to the assumed digital data packet sequence after addition of null packets, and according to the rule information, the number of data packets and null packets to be allocated, And a position of the null packet is determined by allocating the data packet or the null packet to the packet sequence based on the number of already allocated data packets and null packets. The transmission device according to claim 5, wherein
The transmission apparatus characterized in that the number of slots after addition of a null packet included in the correspondence information provided in the PCR rewriting unit is a predetermined positive integer and a factor of the predetermined positive integer. The transmission device according to claim 5, wherein
A transmission apparatus characterized in that the number of slots after adding a null packet included in the correspondence information provided in the PCR rewriting unit is a value with the number of slots in one frame as a unit. The transmission device according to claim 5, wherein
The number of slots after adding a null packet included in the correspondence information provided in the PCR rewriting unit is a value obtained by multiplying the number of slots in one frame by a predetermined positive integer, and the predetermined positive integer in the number of slots in one frame. A transmission apparatus characterized by having a value obtained by multiplying a factor of. A reception device that receives the frame transmitted by the transmission device according to any one of claims 1 to 9, and outputs digital data requested by a user separately from the frame,
A header detection unit that detects a header in the frame and generates a slot allocation number and a slot position of the digital data from the header;
A separation unit that separates and outputs the digital data requested by the user from the frame based on a slot allocation number and a slot position of the digital data generated by the header detection unit;
A clock recovery unit that recovers a clock required when the separation unit outputs digital data based on the transmission rate of the frame; and
The separation unit is
Digital information which is provided with the same correspondence information as the correspondence information provided in the PCR rewriting unit of the transmission device, and a plurality of speeds in units of transmission rate per slot or transmission rate per channel is input by the transmission device Based on the correspondence information defined corresponding to the input speed of data and including any speed that is independent of the speed according to the number of slots constituting one frame , the transmission apparatus inputs And receiving the separated digital data at the output speed that is equal to or higher than the speed of the digital data requested by the user and is the output speed. apparatus.   A transmission program for causing a computer to function as the transmission device according to any one of claims 1 to 9.   A receiving program for causing a computer to function as the receiving device according to claim 10.

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