JP2001168830A - Ts multiplex transmitter and receiver, and transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a TS multiplex transmitter and receiver and a transmission system, where the configuration of the receiver does not require a PLL circuit and a buffer memory in a digital broadcast system that multiplexes a plurality of programs and transmits/receives the multiplexed program. SOLUTION: A slot selection/NULL replacement section 23 of the receiver 2 selects one transport stream from among multiplexed transport streams after demodulation (Figure 2 (a)), according to the control of a frame synchronization/ control information demultiplex section 22. The slot selection/NULL replacement section 23 replaces packets other than each TS packet of the selected transport stream with a NULL packet (hatched parts in Figure 2b), to extract a single transport stream (Figure 2 (b)). Thus, the selected single transport stream can be extracted without conducting velocity conversion processing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a TS multiplex transmitting apparatus, a receiving apparatus, and a transmission system, and more specifically, to a plurality of broadcasters used for digital satellite broadcasting and digital CATV broadcasting. A transmission device for multiplexing and transmitting a transport stream (TS),
The present invention also relates to a receiving device that receives a multiplexed transport stream and selectively outputs a transport stream of an arbitrary broadcaster, and a transmission system including the transmitting device and the receiving device.

[0002]

2. Description of the Related Art In the field of digital satellite broadcasting and digital CATV broadcasting, in order to effectively utilize communication resources, programs provided by a plurality of broadcasters are multiplexed and broadcast on one channel. ing. Hereinafter, a conventional transmitting / receiving apparatus used in a digital broadcasting system for multiplexing and transmitting a plurality of programs will be described with reference to FIGS.
This will be briefly described with reference to FIG. FIG. 13 is a block diagram showing an example of a configuration of a digital broadcasting system using an MPEG (Moving Picture Experts Group) system as an encoding system, and has three broadcasters A to C. FIG. 14 is a diagram illustrating an example of multiplexing performed by the transmitting apparatus 100 in FIG. FIG. 15 shows the receiving device 20 of FIG.
FIG. 3 is a diagram illustrating an example of transport stream selection performed by a transport stream 0.

First, broadcasters A to C generate transport streams TS-A to TS-C of a program to be provided, respectively, according to the MPEG2 standard (FIGS. 14A to 14C).
(C)), and outputs to the multiple TS multiplexing section 101 of the transmitting apparatus 100. In the example of FIG. 14, the broadcaster B transmits four TS packets (B1 to B4) in one frame cycle, as the broadcaster A transmits three TS packets (A1 to A3) in one frame cycle. As described above, the broadcaster C generates a transport stream so as to transmit five TS packets (C1 to C5) in one frame period. In the transmission device 100, the multiple TS multiplexing unit 10
1 performs speed conversion and multiplexing on the transport streams TS-A to TS-C input from the broadcasters A to C, respectively, in units of TS packets constituting the streams, and performs the number of slots N of one frame (N is A multiplexed transport stream of (an integer of 2 or more) is generated (FIG. 14D). In the example of FIG. 14, the multiple TS multiplexing unit 101 multiplexes one frame into 12 slots. In addition, the multiple TS multiplexing unit 101
In order to extract a transport stream to be selected at 0, information on a slot used by each transport stream is added as a transmission control signal. This transmission control signal is, for example, a BS digital broadcast (a plurality of TSs).
Transmission format) is TMCC (Transmission Multip
lexing Configuration Control), which is transmitted by being superimposed on the packet synchronization signal. Modulation section 102 performs predetermined modulation on the multiplexed transport stream, and then transmits the multiplexed transport stream to receiving apparatus 200 via transmission path 103.

On the other hand, in the receiving apparatus 200, the demodulation unit 2
01 receives and demodulates a multiplexed transport stream transmitted via the transmission path 103. The frame synchronization / control information separation unit 202 performs frame synchronization of a multiplexed transport stream, separation / analysis of a transmission control signal, and the like, and additionally provides broadcasters A to C (that is, transport streams TS-A to C). TS-
According to the selection instruction of C), the slot selection / write unit 2
03 and a PLL (Phase locked loop) circuit 204. The slot selecting / writing unit 203 selects one transport stream from the demodulated multiplexed transport stream (FIG. 15A) under the control of the frame synchronization / control information separating unit 202, and Write to. The PLL circuit 204 controls the frame synchronization / control information separation unit 20 so that when the system clock of the receiving device 200 and the system clock of the transmitting device 100 are matched, no problem occurs in the encoding process.
In accordance with the control of 2, a read clock for converting the speed of the selected transport stream written in the buffer memory 205 is generated. Read circuit 206
Reads the selected transport stream from the buffer memory 205 in accordance with the read clock generated by the PLL circuit 204 (FIG. 15B). The system clock reproducing unit 207 outputs the program clock reference value (PC
R: Program Clock Reference)
The clock is reproduced so that the system clock of 00 and the system clock of the transmission device 100 match. MPE
The G decoder 208 decodes the selected transport stream after the speed conversion according to the reproduced system clock, and outputs the decoded transport stream as video / audio.

[0005]

However, the conventional receiving apparatus 200 reproduces the selected transport stream into the original transport stream (at the time of the transmitting apparatus 100). A PLL circuit 204 and a buffer memory 205 are indispensable. Therefore, the configuration of the conventional receiving apparatus 200 as described above has a problem that the receiving apparatus is complicated and expensive.

Therefore, an object of the present invention is to provide a TS multiplex transmitting apparatus and a receiving apparatus which do not require a PLL circuit and a buffer memory as a configuration of a receiving apparatus in a digital broadcasting system for multiplexing and transmitting a plurality of programs. As well as providing a transmission system.

[0007]

According to a first aspect of the present invention, there is provided a receiving apparatus for receiving a multiplexed transport stream multiplexed by assigning a predetermined number of slots to a plurality of transport streams. The apparatus extracts a TS packet at a slot position of a transport stream to be selected from a multiplexed transport stream to be received, and generates a transport stream in which a slot position of an unselected transport stream is replaced with a NULL packet. Slot selection / NULL replacement means, and slot selection / NU
A system clock reproducing unit that reproduces a system clock that gives a decoding timing based on the PCR added to the transport stream output by the LL replacing unit.

As described above, according to the first aspect, each TS of the selected transport stream is converted without performing speed conversion.
A packet other than a packet is replaced with a NULL packet. This eliminates the necessity of configuring the PLL circuit and the buffer memory on the receiving device side, thereby realizing a simple and inexpensive receiving device.

A second invention is an invention according to the first invention, wherein one frame period of the multiplexed transport stream is T, the number of slots of the frame length is N, and allocation of the transport stream to be selected is performed. When the number of slots is n (n <N) and the i-th (i = 1 to n) assigned slot position in the frame is Pi, ΔSTCi = ｛(i−1) / n− (Pi−1) / N ｝ ×
A correction S for calculating the correction value ΔSTCi according to T
It further comprises a TC calculating means, wherein the system clock reproducing means reproduces the system clock based on a value obtained by subtracting the correction value ΔSTCi from the PCR.

As described above, according to the second aspect, the first aspect
In the invention, the time lag caused by not performing the speed conversion is corrected by controlling the system clock.
This enables accurate decoding of the selected transport stream.

[0011] A third invention is an invention according to the first and second inventions, wherein program arrangement information relating to all transport stream selections is provided by one of a plurality of transport streams. When transmitted, the slot selection / NULL replacement means further extracts a TS packet storing a specific PID (packet identifier) giving program sequence information.

As described above, according to the third aspect, the first aspect
And a second invention further extracts a TS packet in which a specific PID giving program sequence information is stored.
Thereby, in addition to the effects of the first and second inventions, the transmitting apparatus does not need to transmit the program arrangement information in all transport streams, so that transmission band resources can be effectively used (saving). .

A fourth invention is a TS multiplex transmission apparatus for generating and transmitting a multiplexed transport stream by multiplexing a plurality of transport streams by assigning a predetermined number of slots to each of the plurality of transport streams. For the transport stream, rate conversion and multiplexing are performed for each TS packet constituting the stream,
A plurality of TS multiplexing means for generating a multiplexed transport stream, a frame period of the multiplexed transport stream is T, the number of slots of the frame length is N, and the number of allocated slots of the target transport stream is n ( n <N), i-th (i = 1 to n) in the frame
If the assigned slot position of is Pi, ΔPCRi = {(Pi−1) / N− (i−1) / n} ×
PCR correction means for calculating a correction value ΔPCRi according to T 1 and adding the correction value ΔPCRi to the current PCR.

As described above, according to the fourth aspect, a time lag caused by not performing the speed conversion on the transmitting device side is added to the PCR to be transmitted in advance. As a result, packets other than each TS packet of the transport stream selected without performing the speed conversion on the
By performing the process of replacing with a UL packet, the PLL
Since there is no need to configure a circuit and a buffer memory, it is possible to realize a receiver that is easy and inexpensive to configure. Further, since the PCR is corrected in advance on the transmitting device side, a conventionally used configuration can be used as it is as the system clock reproducing means on the receiving device side.

[0015] A fifth invention is an invention according to the fourth invention, wherein the plurality of TS multiplexing means is arranged so that, for each of a plurality of transport streams, TS packets constituting the transport stream are not all continuous. The slot assignment is performed by distributing the slots.

As described above, according to the fifth aspect, the fourth aspect
In the invention of the above, the TS of the same transport stream
Multiplexing is performed by allocating slots by distributing packets so that they are not all continuous. Thus, in addition to the effect of the fourth aspect, it is possible to further prevent overflow / underflow from occurring on the receiving device side.

A sixth invention is an invention according to the fifth invention, wherein the plurality of TS multiplexing means performs TS packet allocation processing from a transport stream having a large number of allocated slots.

As described above, according to the sixth aspect, the fifth aspect
In the invention of the first aspect, TS packet allocation processing is performed from a transport stream having a large number of allocated slots. As a result, the slot allocation process can be performed with priority given to a transport stream with a high transmission speed. Therefore, especially when the transport stream is an MPEG video / audio signal reproduced at a constant rate, the receiving apparatus The occurrence of overflow / underflow on the side can be more effectively prevented.

A seventh invention is a transmission system for performing transmission and reception using a multiplexed transport stream multiplexed by allocating a predetermined number of slots to each of the plurality of transport streams. For a stream, the T that makes up the stream
A plurality of TS multiplexing means for performing speed conversion and multiplexing on an S packet basis to generate a multiplexed transport stream; and a frame period of the multiplexed transport stream is T, and the number of slots having a frame length is N. When the number of allocated slots of the transport stream is n (n <N) and the i-th (i = 1 to n) allocated slot position in the frame is Pi, ΔPCRi = ｛(Pi−1) / N− ( i-1) / n｝ ×
A transmission device comprising: a PCR correction means for calculating a correction value ΔPCRi according to T 1 and adding the correction value ΔPCRi to the current PCR; and a TS packet at a slot position of a transport stream to be selected from a multiplexed transport stream to be received. Slot selection / NULL replacement means for extracting and extracting a transport stream in which the slot position of the transport stream not selected is replaced with NULL packets, and PCR added to the transport stream output by the slot selection / NULL replacement means. And a system clock regenerating means for regenerating a system clock for giving a decoding timing based on the receiving device.

As described above, according to the seventh aspect of the present invention, transmission is performed in accordance with the process of replacing packets other than each TS packet of the selected transport stream with NULL packets without performing speed conversion performed on the receiving device side. The time shift caused by not performing the speed conversion on the device side is added to the PCR to be transmitted in advance. This eliminates the necessity of configuring the PLL circuit and the buffer memory on the receiving device side, thereby realizing a simple and inexpensive receiving device. Also, on the transmitting device side,
Since the correction of R is performed, the configuration conventionally used can be used as it is as the system clock reproducing unit on the receiving device side.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a block diagram showing a configuration of a receiving apparatus according to a first embodiment of the present invention. In FIG. 1, a receiving apparatus 2 according to the first embodiment includes a demodulating unit 21
A frame synchronization / control information separation unit 22, a slot selection / NULL replacement unit 23, a corrected STC calculation unit 24,
A system clock reproducing unit 27 and an MPEG decoder 28
And

Receiving device 2 according to the first embodiment of the present invention
Is a device that receives the multiplexed transport stream output from the general transmitting device 100 as described above. Hereinafter, the case where a multiplexed transport stream in which one frame is 12 slots shown in FIG. 12 is transmitted as an example, and the receiving apparatus 2 according to the first embodiment will be further described with reference to FIGS. Will be described. FIG. 2 is a diagram illustrating an example of a transport stream selection process performed by the slot selection / NULL replacement unit 23 in FIG. FIG.
Is a correction value ΔS calculated by the correction STC calculation unit 24 in FIG.
It is a figure explaining an example of TCi. FIG. 4 is a block diagram showing a detailed configuration of the system clock reproducing unit 27 of FIG.

In the receiving apparatus 2, the demodulation unit 21 receives and demodulates the multiplexed transport stream transmitted via the transmission line 13. The frame synchronization / control information separation unit 22 performs frame synchronization of a multiplexed transport stream, separation / analysis of a transmission control signal, and the like.
Broadcaster A given separately (typically from CPU)
To C (that is, the transport streams TS-A to
According to the selection instruction of TS-C), slot selection / NUL
It controls the L replacement unit 23 and the correction STC calculation unit 24.

The slot selection / NULL replacement section 23 selects one transport stream from the demodulated multiplexed transport stream (FIG. 2A) under the control of the frame synchronization / control information separation section 22. . Here, the slot selection / NULL replacement unit 23 extracts a single transport stream by replacing packets other than each TS packet of the selected transport stream with NULL packets (shaded portions in the figure) (FIG. 2).
(B)). As a result, a single selected transport stream can be extracted without performing the speed conversion process. The selected transport stream that has been replaced with the NULL packet is an MPEG decoder 2
8 is output.

The correction STC calculating section 24 calculates a correction value ΔSTC for correcting a system clock reproduced by a system clock reproducing section 27 described later. This is because when the selected transport stream formed by the slot selection / NULL replacement unit 23 is decoded by the MPEG decoder 28, the system clock is reproduced by the system clock reproducing unit 27 based on the PCR added to the selected transport stream. This is because the clock is shifted with respect to the clock required for actual decoding. Therefore, the corrected STC calculation unit 24 calculates the position of the packet of the selected transport stream (FIG. 3A) and the position of the TS packet when the speed of the selected transport stream is converted (played back to the original transport stream). The time difference from (FIG. 3B) is obtained for each TS packet, and is output to the system clock reproducing unit 27 as a correction value ΔSTCi (i is a packet number within one frame). Since the slot position of each TS packet in a frame is the same in all frames,
The correction value ΔSTCi may be calculated for any one frame. Specifically, the correction value ΔSTCi is N for the number of slots of the frame length, T for the frame period (time), n (n <N) for the number of slots for packet allocation of the selected transport stream, and the i-th frame ( When the assigned slot position of i = 1 to n) is Pi, it is obtained according to the following equation (1). ΔSTCi = {(i−1) / n− (Pi−1) / N} × T (1) In the example of FIG. 3, the correction value ΔSTC1 when the transport stream of the broadcaster C is selected. ~
ΔSTC5 is shown.

Next, referring to FIG. 4, the system clock reproducing unit 27 includes an adding / subtracting circuit 51, a low-pass filter (LPF) 52, a voltage-controlled oscillator (VCO) 53,
And a counter 54. The addition / subtraction circuit 51 is an MPEG
The PCR added from the decoder 28 in the selected transport stream, the correction value ΔSTCi calculated from the correction STC calculation unit 24, and the STC (system clock count value) fed back from the counter 54 are input, respectively. An error signal is calculated for each TS packet according to the following equation (2). Error signal = STC + ΔSTCi-PCR (2) This error signal is input to the VCO 53 via the LPF 52. The VCO 53 controls the frequency of the generated system clock based on the error signal and outputs the frequency to the counter 54. The counter 54 counts the system clock output from the VCO 53 and feeds it back to the addition / subtraction circuit 51. This makes it possible to reproduce the system clock corresponding to each TS packet of the selected transport stream.

The MPEG decoder 28 decodes the selected transport stream to be input according to the system clock reproduced by the system clock reproducing section 27 and outputs it as video / audio.

As described above, according to the receiving apparatus according to the first embodiment of the present invention, packets other than each TS packet of the selected transport stream are replaced with NULL packets without performing speed conversion. Then, a time shift caused by not performing the speed conversion is corrected by controlling the system clock. This eliminates the necessity of configuring the PLL circuit and the buffer memory on the receiving device side, thereby realizing a simple and inexpensive receiving device.

(Second Embodiment) In the first embodiment, the case where the time lag caused by not performing the speed conversion is corrected by controlling the system clock on the receiving device 2 side has been described. Next, in a second embodiment of the present invention,
A transmission system (TS multiplex transmission apparatus and reception apparatus) that realizes an easy-to-configure and inexpensive reception apparatus by adding a time lag to PCR in advance on the transmission apparatus side.
I will provide a.

FIG. 5 is a block diagram showing a configuration of a transmission system according to the second embodiment of the present invention. In FIG. 5, the transmission system according to the second embodiment of the present invention has T
The S multiplex transmission device 1 and the reception device 3 are connected by a transmission line 13. The TS multiplexing transmission device 1 includes a plurality of TSs.
A multiplexing unit 11 and a modulation unit 12 are provided. In addition, the receiving device 3 includes a demodulation unit 21, a frame synchronization / control information separation unit 22, a slot selection / NULL replacement unit 23, a system clock reproduction unit 37, and an MPEG decoder 28. In the receiving device 3 of the second embodiment, the same components as those of the receiving device 2 according to the first embodiment are denoted by the same reference numerals.

First, the operation of the TS multiplex transmission apparatus 1 will be described. As described above, each of the broadcasters A to C
In accordance with the G2 standard, transport streams TS-A to TS-C of a program to be provided are respectively generated (FIG. 12).
(See (a) to (c)) and output to the multiple TS multiplexing unit 11 of the TS multiplexing transmission device 1. Multiple TS multiplexing unit 11
Multiplexes transport streams TS-A to TS-C input from the broadcasters A to C, respectively, by speed conversion and multiplexing in units of TS packets constituting the streams, and multiplexing the number of slots N in one frame. A stream is generated (see FIG. 12D). Here, the multiple TS multiplexing unit 11 obtains a time difference that fluctuates due to the speed conversion and the multiplexing as a correction value ΔPCRi (i is a packet number within one frame) for each TS packet. ΔPCR for PCR
Each is rewritten to a value obtained by adding i. This correction value ΔPCR
Specifically, i is N, the number of slots of the frame length is T, the frame period (time) is T, the number of slots to which the target transport stream is allocated packets is n (n <N),
When the i-th (i = 1 to n) assigned slot position in the frame is Pi, it is obtained according to the following equation (3). ΔPCRi = {(Pi−1) / N− (i−1) / n} × T (3)

The modulating unit 12 performs a predetermined modulation on the multiplexed transport stream after PCR rewriting output from the multiple TS multiplexing unit 11, and then transmits it to the receiving device 3 via the transmission line 13. .

Next, the operation of the receiving device 3 will be described. The demodulation unit 21 receives and demodulates the multiplexed transport stream transmitted via the transmission path 13. The frame synchronization / control information separation section 22 performs frame synchronization of a multiplexed transport stream, separation / analysis of a transmission control signal, and the like, and additionally provides broadcasters A to C (typically from a CPU) (that is, the broadcasters A to C). , TS-A to TS-C), and controls the slot selection / NULL replacement unit 23.

Under the control of the frame synchronization / control information separation unit 22, the slot selection / NULL replacement unit 23 converts one of the demodulated multiplexed transport streams (see FIG. 2A) into one transport stream. select. Here, the slot selection / NULL replacement unit 23 extracts a single transport stream by replacing packets other than each TS packet of the selected transport stream with NULL packets (see FIG. 2B). As a result, a single selected transport stream can be extracted without performing the speed conversion process.
The selected transport stream replaced with the NULL packet is output to the MPEG decoder 28.

The system clock reproducing section 37 has a conventionally used configuration. As shown in FIG. 6, a subtraction circuit 61, a low-pass filter (LPF) 52, a voltage controlled oscillator (VCO) 53, a counter 54.
The subtraction circuit 61 receives the PCR added from the MPEG decoder 28 in the selected transport stream and the STC fed back from the counter 54, and calculates an error signal for each TS packet according to the following equation (4). I do. Error signal = STC-PCR (4) This error signal is input to the VCO 53 via the LPF 52. The VCO 53 controls the frequency of the generated system clock based on the error signal and outputs the frequency to the counter 54. The counter 54 counts the system clock output from the VCO 53 and outputs the result to the subtraction circuit 61 by feedback. This makes it possible to reproduce the system clock corresponding to each TS packet of the selected transport stream.

The MPEG decoder 28 decodes the input selected transport stream in accordance with the system clock reproduced by the system clock reproducing section 37 and outputs it as video / audio.

As described above, according to the transmission system according to the second embodiment of the present invention, packets other than each TS packet of the selected transport stream are converted into NULL packets without performing the speed conversion performed on the receiving device side. In response to the replacement process, a time shift caused by not performing the speed conversion on the transmission device side is added in advance to the PCR to be transmitted. This eliminates the necessity of configuring the PLL circuit and the buffer memory on the receiving device side, thereby realizing a simple and inexpensive receiving device. In addition, since the transmitting device performs PCR correction in advance,
As the system clock reproducing unit on the receiving device side, the configuration conventionally used can be used as it is.

(Third Embodiment) In the transmitters of the first and second embodiments, as shown in FIG. 2A, each transport stream TS-A provided by broadcasters A to C is provided. 〜TS-C have been multiplexed by allocating consecutive slots of TS packets of the same transport stream. Therefore, on the receiving device side,
The delay time of the TS packet is not constant, and the reproduction processing speed of the selected transport stream may not catch up or may not be enough for the time to be reproduced, which may cause overflow / underflow. Therefore, a third embodiment of the present invention provides a TS multiplexing transmission device that prevents occurrence of overflow / underflow on the receiving device side by multiplexing each TS packet by discontinuous slot allocation.

FIG. 7 is a graph showing a T value according to the third embodiment of the present invention.
FIG. 2 is a block diagram illustrating a configuration of an S-multiplex transmission apparatus. FIG.
, The TS multiplexing transmission device 4 according to the third embodiment of the present invention includes a multiple TS multiplexing unit 41 and a modulation unit 12. Note that the TS multiplex transmission apparatus 4 of the third embodiment
, The same components as those of the TS multiplex transmission apparatus 1 according to the second embodiment are denoted by the same reference numerals. Further, as a receiving device corresponding to the TS multiplexing transmitting device 4 according to the third embodiment, any of the receiving devices 2 and 3 described in the first or second embodiment can be used. . FIGS. 8 and 10 are diagrams illustrating an example of multiplexing performed by the multiple TS multiplexing unit 41 of FIG. 7, respectively. FIGS. 9 and 11 show that the TS multiplexing and transmitting apparatus 4 according to the third embodiment of the present invention corresponds to FIGS.
0 for the multiplexed transport stream output according to the multiplexing shown in FIG.
FIG. 4 is a diagram illustrating an example of a transport stream selection process performed by a UL replacement unit.

As described above, the broadcasters A to C make the MP
According to the EG2 standard, the transport streams TS-A to TS-C of the program to be provided are respectively generated (FIG. 8).
(A) to (c), and FIGS. 10 (a) to (c)), and outputs to the multiple TS multiplexing unit 41 of the TS multiplexing transmission device 4. Multiple T
The S multiplexing unit 41 speed-converts and multiplexes the transport streams TS-A to TS-C input from the broadcasters A to C, respectively, in units of TS packets constituting the streams, and performs the number of slots N per frame.
To generate a multiplexed transport stream. Here, the multiple TS multiplexing unit 41 distributes the TS packets of each of the transport streams TS-A to TS-C so that they are not all continuous, and performs slot allocation. Several methods are conceivable as a method of distributing the TS packets and allocating the slots, and two specific methods will be specifically described below by way of example.

First, the first method will be described with reference to FIGS. The first method is to perform slot allocation according to the following equation (5) on the assumption that the i-th (i = 1 to n) allocated slot position in a frame is Pi, based on the following conditions. . Note that fl
oor (x) is a function for truncating the value x below the decimal point. Pi = floor {N * (i-1) / n} +1 (5) [Conditions]-Processing is performed from a transport stream with a large number of allocated slots. If the obtained Pi has already been assigned, assign it to P (i + 1).

According to the above equation (5), FIGS.
When the slot assignment of each TS packet shown in (c) is performed, the frame shown in FIG. 8D is configured. More specifically, the processing is started from the transport stream TS-C having a large number of allocated slots, and the slot position of each TS packet is as follows. C1: floor [12 * (1-1) / 5] + 1 = 1 C2: floor [12 * (2-1) / 5] + 1 = 3 C3: floor [12 * (3-1) / 5] + 1 = 5 C4: floor [12 * (4-1) / 5] + 1 = 8 C5: floor [12 * (5-1) / 5] + 1 = 10 B1: floor [12 * (1-1) ) / 4] + 1 = 1 (allocated) → 2 B2: floor [12 * (2-1) / 4] + 1 = 4 B3: floor [12 * (3-1) / 4] + 1 = 7 B4: floor [12 * (4-1) / 4] + 1 = 10 (allocated) → 11 A1: floor [12 * (1-1) / 3] + 1 = 1 (allocated) → 6 A2: floor [12 * (2-1) / 3] + 1 = 5 (allocated) → 9 A3: floor [12 * (3-1) / 3] + 1 = 9 (allocated) → 12

Next, the second method will be described with reference to FIGS. In the second method, the total number of transport streams to be processed is S, the order in which the transport streams are processed is r (r = 1, 2,...), And the i-th (i = 1 to n) If the provisional slot position to be assigned is Pi, the slot assignment is performed according to the following equation (6) on the assumption that the following conditions are satisfied. Note that floor (x) is a function for rounding down the value x below the decimal point. Pi = floor {N * (i-1) / n} + floor {(r-1) * N / S} +1 (6) [Conditions] Processing is performed from a transport stream having a large number of allocated slots. If the calculated Pi exceeds the number N of slots in one frame, the Pi is assigned as Pi ← (N−Pi). If the obtained Pi has already been assigned, assign it to P (i + 1). -For each transport stream, the TS packets assigned to each slot are rearranged in chronological order.

According to the above equation (6), FIGS.
When the slot assignment of each TS packet shown in (c) is performed, the frame shown in FIG. 10D is configured. Specifically, the processing is started from the transport stream TS-C having a large number of allocated slots, and the temporary slot positions of each TS packet are as follows. C1: floor [12 * (1-1) / 5] + floor [(1-1) * 12/3] + 1 = 1 C2: floor [12 * (2-1) / 5] + floor [(1 -1) * 12/3] + 1 = 3 C3: floor [12 * (3-1) / 5] + floor [(1-1) * 12/3] + 1 = 5 C4: floor [12 * ( 4-1) / 5] + floor [(1-1) * 12/3] + 1 = 8 C5: floor [12 * (5-1) / 5] + floor [(1-1) * 12/3 ] + 1 = 10 B1: floor [12 * (1-1) / 4] + floor [(2-1) * 12/3] + 1 = 5 (allocated) → 6 B2: floor [12 * (2 -1) / 4] + floor [(2-1) * 12/3] + 1 = 8 (allocated) → 9 B3: floor [12 * (3-1) / 4] + floor [(2-1 ) * 12/3] + 1 = 11 B4: floor [12 * (4-1) / 4] + floor [(2-1) * 12/3] + 1 = 2 A1: floor [12 * (1- 1) / 3] + floor [(3-1) * 12/3] + 1 = 9 (assigned) → 12 A2: floor [12 * (2-1) / 3] + floor [(3-1) * 12/3] + 1 = 1 (allocated) → 4 A3: floor [12 * (3-1) / 3] + floor [(3-1) * 12/3] + 1 = 5 (allocated) → 7 Then, the transport streams TS-B and TS
Regarding -A, the TS packets at each slot position are rearranged in chronological order.

As described above, in the first method, the process of allocating the TS packets of all the transport streams from the first slot is performed. Therefore, the transport stream to be processed later (for example, TS-
A), the allocation position of the TS packet tends to be shifted toward the rear of the frame, that is, the delay time (jitter) tends to increase, but there is an advantage that it is not necessary to rearrange the position of the TS packet in chronological order. On the other hand, in the second method, it is necessary to rearrange the TS packet positions in chronological order after allocating the slot positions. There is an advantage that it is possible (the average delay time is reduced). In both the first and second methods, the slot assignment does not change unless the number of slots assigned to each transport stream changes. Therefore, even when a transmission error occurs in the transmission control signal (slot information used by each transport stream) transmitted from the transmitting device, the receiving device uses the immediately preceding transmission control signal to transmit the transport stream. There is an advantage that the selection process can be continued accurately.

In the first and second methods, the case where processing is performed from a transport stream with a large number of allocated slots has been described as a condition. However, even if processing is performed from a transport stream with a small number of allocated slots, Slot positions can be distributed and assigned. However, the capacity of the buffer memory configured on the receiving device side needs to be (delay time amount × transmission rate), and the delay time increases as the transport stream for which slot allocation processing is performed later as described above. In consideration of the above, the transport stream with a smaller number of allocated slots (slower transmission speed) requires less buffer memory capacity for processing if the delay time is the same. Therefore, when the transport stream is an MPEG video / audio signal reproduced at a constant rate, in order to prevent overflow / underflow from occurring on the receiving device side,
It is preferable to perform slot allocation processing in order from a transport stream having a large number of allocated slots (high transmission speed).

Here, as the next-generation transmission method, the number of slots in one frame is "53", and the first slot of the frame is a frame header for storing transmission control information (frame synchronization signal, TS packet arrangement information, etc.). Digital CATV that is currently being standardized
Of the multiple TS transmission schemes. When the slot allocation method provided by the present invention is applied to such a transmission system, the following processing may be performed. The total number of slots allocated to each transport stream is set to within “52”, and the above-described slot allocation processing is first performed. Next, the position of the slot to which the TS packet was not allocated in this processing is extracted, and the TS packets at all the slot positions are rotated or some of the slots are rotated so that the first slot of the frame becomes the frame header according to the position. The TS packet at the position is slid and rearranged. For example, as a rotation method, when the tenth slot position is extracted,
The TS packet at the eleventh slot position is arranged at the second slot position, the TS packet at the twelfth slot position is arranged at the third slot position, and the TS packet at the ninth slot position is arranged at the 53rd slot position. Replace. As a slide method, when the tenth slot position is extracted, the TS of the first slot position is extracted.
The packet is rearranged at the second slot position, the TS packet at the second slot position is rearranged at the third slot position, and the TS packet at the ninth slot position is rearranged at the tenth slot position. The TS packets at the 53rd slot position are not rearranged.) The correspondence between each slot position and the TS packet based on this slot assignment process is stored as TS packet arrangement information in the frame header.

When the receiving device is the receiving device 3 described in the second embodiment, the multiple TS multiplexing unit 41
When the slot assignment process is completed, next, similarly to the multiple TS multiplexing unit 11 of the second embodiment, the time difference that fluctuates due to the speed conversion and the multiplexing is set as a correction value ΔPCRi for each TS packet. Ask for the current P
Each is rewritten to a value obtained by adding ΔPCRi to CR. On the other hand, the receiving device is the receiving device 2 described in the first embodiment.
In the case of, the multiple TS multiplexing unit 41 does not rewrite the PCR.

The modulating section 12 allocates a distributed slot (and rewrites PCR) output from the multiple TS multiplexing section 41.
After performing a predetermined modulation on the multiplexed transport stream after the processing, the multiplexed transport stream is transmitted to the receiving apparatuses 2 and 3 via the transmission path 13. Then, the slot selection / NULL replacement unit 23 of the receiving devices 2 and 3 performs the processing described in the first and second embodiments to thereby receive the multiplexed transport stream (FIG. 9A or FIG. 9A). 11
Based on (a)), each frame as shown in FIG. 9B or FIG. 11B is configured.

As described above, according to the TS multiplex transmission apparatus according to the third embodiment of the present invention, the first and second transmission
In addition to the processing of the embodiment, multiplexing is performed by distributing the TS packets of the same transport stream so that they are not all continuous and by allocating slots. Thus, in addition to the effects of the first and second embodiments, it is possible to further prevent overflow / underflow from occurring on the receiving device side.

In the first to third embodiments, the receiving device side selects the TS of the selected transport stream.
Does not perform packet speed conversion. Therefore, by utilizing this, only one of the transport streams provided by a plurality of broadcasters in the transmitting apparatus is provided with the program arrangement information (for example, BS digital A TS packet storing a specific PID (packet identifier) for providing this program arrangement information together with the selected transport stream in the receiving device so as to transmit “all-station SI (Service Information)” specified by broadcasting. (Regardless of the selection / non-selection of the transport stream), it is also possible to extract a single transport stream. FIG. 12 shows that the specific PID is TS
An example in which the transport stream TS-B is selected by the slot selection / NULL replacement unit 23 in the case where the transport stream TS-B is stored in the packet “A2” is shown. This allows
Since the transmitting apparatus does not need to transmit the program arrangement information in all transport streams, it is possible to effectively use (saving) transmission band resources.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a receiving device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a transport stream selection process performed by a slot selection / NULL replacement unit 23 in FIG. 1;

FIG. 3 shows ΔST calculated by a correction STC calculator 24 in FIG. 1;
It is a figure explaining an example of C.

FIG. 4 is a block diagram illustrating a detailed configuration of a system clock reproducing unit 27 of FIG. 1;

FIG. 5 is a block diagram illustrating a configuration of a transmission system according to a second embodiment of the present invention.

FIG. 6 is a block diagram showing a detailed configuration of a system clock reproducing unit 37 of FIG.

FIG. 7 is a block diagram illustrating a configuration of a TS multiplexing transmission apparatus according to a third embodiment of the present invention.

8 is a diagram illustrating an example of multiplexing performed by the multiple TS multiplexing unit 41 in FIG. 7;

9 is a diagram illustrating an example of a transport stream selection process performed by the slot selection / NULL replacement unit 23 in FIGS. 1 and 5 on a multiplexed transport stream output according to the multiplexing illustrated in FIG. 8;

FIG. 10 is a diagram illustrating an example of multiplexing performed by the multiple TS multiplexing unit 41 in FIG. 7;

11 is a diagram illustrating an example of a transport stream selection process performed by the slot selection / NULL replacement unit 23 in FIGS. 1 and 5 on a multiplexed transport stream output according to the multiplexing illustrated in FIG. 10;

FIG. 12 is a diagram illustrating an example of a transport stream selection process performed by the slot selection / NULL replacement unit 23 in FIGS. 1 and 5;

FIG. 13 is a block diagram illustrating an example of a configuration of a conventional digital broadcasting system.

FIG. 14 is a diagram illustrating an example of multiplexing performed by the transmitting apparatus 100 of FIG.

15 is a diagram illustrating an example of a transport stream selection process performed by the reception device 200 of FIG.

[Explanation of symbols]

 1, 4, 100: TS multiplex transmitting apparatus 2, 3, 200: Receiving apparatus 11, 41, 101: Multiple TS multiplexing sections 12, 102: Modulating section 13, 103: Transmission path 21, 201: Demodulating section 22, 202: Frame synchronization / control information separation unit 23: Slot selection / NULL replacement unit 24: Correction STC calculation unit 27, 37, 207: System clock reproduction unit 28, 208: MPEG decoder 51: Addition / subtraction circuit 52: Low-pass filter (LPF) 53: voltage controlled oscillator (VCO) 54: counter 61: subtraction circuit 203: slot selection / write unit 204: PLL circuit 205: buffer memory 206: read circuit

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Hiroshi Koga 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Masashi Shimodaira 1006 Kadoma Kadoma, Kadoma City Osaka Pref. F term (reference) 5C063 AA20 AB03 AB07 AC01 AC05 CA12 CA14 CA20 CA23 CA31 CA40 5K028 KK01 KK03 KK32 LL12 NN32 5K030 HA08 HB15 JA01 KA21 LA15

Claims (7)

[Claims] 1. A receiving apparatus for receiving a multiplexed transport stream multiplexed by assigning a predetermined number of slots to each of a plurality of transport streams, wherein the receiving apparatus receives the multiplexed transport stream from the multiplexed transport stream. A slot selection / NULL replacement means for extracting a TS packet at a slot position of a transport stream to be selected and generating a transport stream in which a slot position of a transport stream not selected is replaced with a NULL packet; A system clock reproducing means for reproducing a system clock giving a decoding timing based on a PCR (program clock reference value) added to the transport stream output by the NULL replacing means. The receiving device. 2. A frame cycle of the multiplexed transport stream is T, the number of slots of the frame length is N, the number of allocated slots of the transport stream to be selected is n (n <N), and the i-th frame in the frame is selected. (I = 1 ~
When the assigned slot position of n) is Pi, ΔSTCi = {(i−1) / n− (Pi−1) / N} ×
A correction S for calculating the correction value ΔSTCi according to T
The receiving apparatus according to claim 1, further comprising a TC calculating unit, wherein the system clock reproducing unit reproduces the system clock based on a value obtained by subtracting the correction value ΔSTCi from the PCR. 3. When the program arrangement information relating to all transport stream selections is transmitted by any one of the plurality of transport streams, the slot selection / NULL replacement means comprises: Extracting a TS packet in which a specific PID (packet identifier) giving information is stored,
The receiving device according to claim 1. 4. A Tx for generating and transmitting a multiplexed transport stream multiplexed by allocating a predetermined number of slots to each of a plurality of transport streams.
An S-multiplex transmission apparatus, comprising: a plurality of TS multiplexing means for speed-converting and multiplexing each of the plurality of transport streams in units of TS packets constituting the stream to generate a multiplexed transport stream; One frame period of the transport stream is T, the number of slots of the frame length is N, and the number of allocated slots of the target transport stream is n.
(N <N), when the i-th (i = 1 to n) assigned slot position in the frame is Pi, ΔPCRi = {(Pi−1) / N− (i−1) / n} ×
A TS multiplexing transmission device comprising: PCR correction means for calculating a correction value ΔPCRi according to T 1 and adding the correction value ΔPCRi to the current PCR. 5. The multi-TS multiplexing means, for each of the plurality of transport streams, performs slot allocation by dispersing so that all TS packets constituting the transport stream are not continuous. The TS multiplex transmission apparatus according to claim 4. 6. The multi-TS multiplexing means performs TS packet allocation processing from a transport stream having a large number of allocated slots.
3. The TS multiplex transmission apparatus according to 1. 7. A transmission system for performing transmission / reception using a multiplexed transport stream multiplexed by allocating a predetermined number of slots to each of a plurality of transport streams, wherein: A plurality of TS multiplexing means for performing speed conversion and multiplexing for each TS packet constituting the stream to generate a multiplexed transport stream; and a frame period of the multiplexed transport stream is T, and the number of slots having a frame length is N. And the number of allocated slots of the target transport stream is n.
(N <N), when the i-th (i = 1 to n) assigned slot position in the frame is Pi, ΔPCRi = {(Pi−1) / N− (i−1) / n} ×
A transmission device comprising: a PCR correction means for calculating a correction value ΔPCRi in accordance with T and adding the correction value to the current PCR; and a TS packet at a slot position of a transport stream to be selected from the multiplexed transport stream to be received. And a slot selection / NULL replacement means for generating a transport stream in which a slot position of an unselected transport stream is replaced by a NULL packet; and a transport stream output by the slot selection / NULL replacement means. A transmission system comprising: a system clock regeneration unit that regenerates a system clock that gives a decoding timing based on the present PCR.