JP4374107B2 - TS multiplexing transmitter, receiver and transmission system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a TS multiplexing transmission device, a reception device, and a transmission system, and more specifically, transport streams (TS) provided by a plurality of broadcasters used for digital satellite broadcasting, digital CATV broadcasting, and the like. The present invention relates to a transmission device that multiplexes and transmits, a reception device that receives a multiplexed transport stream and selectively outputs a transport stream of an arbitrary broadcaster, and a transmission system including the transmission device and the reception device. .
[0002]
[Prior art]
In fields such as digital satellite broadcasting and digital CATV broadcasting, in order to make effective use of communication resources, programs provided by a plurality of broadcasters are multiplexed and broadcast on a single channel.
Hereinafter, a conventional transmission / reception apparatus used in a digital broadcasting system that multiplexes and transmits a plurality of programs will be briefly described with reference to FIGS. FIG. 13 is a block diagram showing an example of the 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 transmission apparatus 100 of FIG. FIG. 15 is a diagram illustrating an example of transport stream selection performed by the reception device 200 of FIG.
[0003]
First, the broadcasters A to C respectively generate transport streams TS-A to TS-C of programs to be provided according to the MPEG2 standard (FIGS. 14A to 14C), and a plurality of TSs of the transmission device 100. The data is output to the multiplexing unit 101. 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 101 converts and multiplexes the transport streams TS-A to TS-C respectively input from the broadcasters A to C in units of TS packets constituting the stream, A multiplexed transport stream having the number N of slots of one frame (N is 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 as 12 slots. Also, the multiple TS multiplexing section 101 adds information on the slot used by each transport stream as a transmission control signal in order to extract a transport stream selected by the receiving apparatus 200. This transmission control signal is called TMCC (Transmission Multiplexing Configuration Control) in BS digital broadcasting (multiple TS transmission format), for example, and is transmitted by being superimposed on a 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.
[0004]
On the other hand, in the receiving apparatus 200, the demodulator 201 receives and demodulates the multiplexed transport stream transmitted via the transmission path 103. The frame synchronization / control information separation unit 202 performs frame synchronization of multiplexed transport streams, separation / analysis of transmission control signals, and the like, and broadcasters A to C (that is, transport streams TS-A to The slot selection / writing unit 203 and a PLL (Phase locked loop) circuit 204 are controlled in accordance with the selection instruction of TS-C). The slot selection / writing unit 203 selects one transport stream from the demodulated multiplexed transport stream (FIG. 15A) according to the control of the frame synchronization / control information separation unit 202, and the buffer memory 205 Write to. The PLL circuit 204 performs buffer memory according to the control of the frame synchronization / control information separation unit 202 so that no trouble occurs in the encoding process when the system clock of the receiving apparatus 200 and the system clock of the transmitting apparatus 100 are matched. A read clock for converting the speed of the selected transport stream written in 205 is generated. The 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 recovery unit 207 matches the system clock of the receiving device 200 and the system clock of the transmitting device 100 based on a program clock reference value (PCR) added in the selected transport stream. To play the clock. The MPEG decoder 208 decodes the selected transport stream after speed conversion in accordance with the reproduced system clock and outputs it as video / audio.
[0005]
[Problems to be solved by the invention]
However, since the conventional receiving apparatus 200 reproduces the selected transport stream into the original transport stream (at the time of the transmitting apparatus 100), the PLL circuit 204 and the buffer memory for converting the speed of each TS packet of the stream 205 is indispensable.
For this reason, the configuration of the conventional receiving apparatus 200 as described above has a problem that the receiving apparatus is complicated and expensive.
[0006]
  SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a PLL circuit and a configuration as a receiving apparatus side in a digital broadcasting system that multiplexes and transmits a plurality of programs.For speed conversion processingBuffer memory(Hereinafter simply referred to as buffer memory)It is to provide a TS multiplexing transmission device, a reception device, and a transmission system that do not require the transmission.
[0007]
[Means for Solving the Problems and Effects of the Invention]
  A first aspect of the invention is a receiving device that receives a multiplexed transport stream that is multiplexed by assigning a predetermined number of slots for each of a plurality of transport streams.
  Slot selection / NULL for generating a transport stream by extracting a TS packet at a slot position of a selected transport stream from a received multiplexed transport stream and replacing a slot position of an unselected transport stream with a NULL packet A replacement means;
  The frame period of the multiplexed transport stream is T, the number of slots of the frame length is N, the number of assigned slots of the transport stream to be selected is n (n <N), and the i-th (i = If the assigned slot position of 1 to n) is Pi,
    ΔSTCi = {(i−1) / n− (Pi−1) / N} × T
And a correction STC calculation means for calculating the correction value ΔSTCi, respectively.
  PCR (program clock reference value) added to the transport stream output by the slot selection / NULL replacement meansThe value obtained by subtracting the correction value ΔSTCi fromAnd a system clock recovery means for recovering a system clock that gives a timing for decoding.
[0008]
  As described above, according to the first aspect, packets other than each TS packet of the selected transport stream are replaced with NULL packets without performing speed conversion.
  This eliminates the need for configuring the PLL circuit and the buffer memory on the receiving device side, thereby realizing a receiving device that is easy to configure and inexpensive.
  Further, a time lag caused by not performing speed conversion is corrected by controlling the system clock.
  As a result, the transport stream to be selected can be accurately decoded.
[0011]
  First2The invention of the1'sAn invention dependent on the invention,
  When program arrangement information related to all transport stream channel selections is transmitted by any one of a plurality of transport streams,
  The slot selection / NULL replacement means further extracts a TS packet storing a specific PID (packet identifier) giving program arrangement information.
[0012]
  As above,2According to the invention of No.1'sIn the present invention, a TS packet storing a specific PID giving program arrangement information is further extracted.
  As a result,1'sIn addition to the effects of the invention, it is not necessary for the transmission apparatus side to transmit the program arrangement information in all transport streams, so that transmission band resources can be effectively utilized (saved).
[0013]
  First3The present invention is a TS multiplexing transmission apparatus for generating and transmitting a multiplexed transport stream in which a plurality of transport streams are multiplexed by assigning a predetermined number of slots respectively.
  A plurality of TS multiplexing means for generating a multiplexed transport stream by converting and multiplexing the speed of each transport packet in units of TS packets constituting the plurality of transport streams,
  The frame period of the multiplexed transport stream is T, the number of slots of the frame length is N, the number of assigned slots of the target transport stream is n (n <N), and the i-th (i = 1 to 1) in the frame n) If the assigned slot position is Pi,
    ΔPCRi = {(Pi−1) / N− (i−1) / n} × T
And a PCR correction means for calculating the correction value ΔPCRi and adding the correction value ΔPCRi to the current PCR.
[0014]
  As above,3According to this invention, a time lag caused by not performing speed conversion on the transmitting device side is added in advance to the PCR to be transmitted.
  As a result, it is not necessary to configure the PLL circuit and the buffer memory by performing processing for replacing packets other than each TS packet of the transport stream to be selected without performing speed conversion on the receiving device side with a NULL packet. Therefore, it is possible to realize an easy and inexpensive receiving apparatus. In addition, since the PCR is corrected in advance on the transmission device side, the conventionally used configuration can be used as it is as the system clock recovery means on the reception device side.
[0015]
  First4The invention of the3An invention subordinate to the invention of
  The plurality of TS multiplexing means is characterized in that slot allocation is performed for each of a plurality of transport streams by distributing the TS packets constituting the transport stream so that they are not all continuous.
[0016]
  As above,4According to the invention of No.3In this invention, the TS packets of the same transport stream are multiplexed so as not to be continuous and multiplexed by slot allocation.
  As a result,3In addition to the effects of the present invention, the occurrence of overflow / underflow on the receiving apparatus side can be prevented.
[0017]
  First5The invention of the4An invention subordinate to the invention of
  The multiple TS multiplexing means is characterized by performing TS packet allocation processing from a transport stream having a large number of allocated slots.
[0018]
  As above,5According to the invention of No.4In this invention, 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 having a high transmission speed. Therefore, particularly 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.
[0019]
  First6The present invention is a transmission system that performs transmission and reception using a multiplexed transport stream obtained by assigning and multiplexing a predetermined number of slots for a plurality of transport streams,
  A plurality of TS multiplexing means for generating a multiplexed transport stream by converting and multiplexing the speed of each transport packet in units of TS packets constituting the plurality of transport streams,
  The frame period of the multiplexed transport stream is T, the number of slots of the frame length is N, the number of assigned slots of the target transport stream is n (n <N), and the i-th (i = 1 to 1) in the frame n) If the assigned slot position is Pi,
    ΔPCRi = {(Pi−1) / N− (i−1) / n} × T
And a PCR correction means for calculating and adding the correction value ΔPCRi to the current PCR, respectively,
  Slot selection / NULL for generating a transport stream by extracting a TS packet at a slot position of a selected transport stream from a received multiplexed transport stream and replacing a slot position of an unselected transport stream with a NULL packet A replacement means;
  The receiving apparatus includes a system clock recovery means for recovering a system clock for providing a decoding timing based on the PCR added to the transport stream output from the slot selection / NULL replacement means.
[0020]
  As above,6According to the invention, the transmission device side does not perform the speed conversion in response to the process of replacing the packets other than each TS packet of the selected transport stream with the NULL packet without performing the speed conversion performed on the reception device side. The generated time lag is added in advance to the PCR to be transmitted.
  This eliminates the need for configuring the PLL circuit and the buffer memory on the receiving device side, thereby realizing a receiving device that is easy to configure and inexpensive. In addition, 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 recovery unit on the receiving device side.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a block diagram showing a configuration of a receiving apparatus according to the first embodiment of the present invention. In FIG. 1, the receiving apparatus 2 according to the first embodiment includes a demodulation unit 21, a frame synchronization / control information separation unit 22, a slot selection / NULL replacement unit 23, a corrected STC calculation unit 24, and a system clock recovery. A unit 27 and an MPEG decoder 28 are provided.
[0022]
The reception apparatus 2 according to the first embodiment of the present invention is an apparatus that receives a multiplexed transport stream output from the general transmission apparatus 100 as described above.
Hereinafter, the receiving apparatus 2 according to the first embodiment will be described with reference to FIG. 2 to FIG. 4 further, taking as an example the case where a multiplexed transport stream having 12 slots per frame shown in FIG. 12 is transmitted. The operation of 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 of FIG. FIG. 3 is a diagram illustrating an example of the correction value ΔSTCi calculated by the correction STC calculation unit 24 of FIG. FIG. 4 is a block diagram showing a detailed configuration of the system clock recovery unit 27 of FIG.
[0023]
In the receiving device 2, the demodulation unit 21 receives and demodulates the multiplexed transport stream transmitted via the transmission path 13. The frame synchronization / control information separation unit 22 performs frame synchronization of the multiplexed transport stream, separation / analysis of transmission control signals, and the like, and broadcasters A to C (that is, typically given from the CPU) (ie, from the broadcasters A to C). The slot selection / NULL replacement unit 23 and the corrected STC calculation unit 24 are controlled according to the selection instruction of the transport streams TS-A to TS-C).
[0024]
The slot selection / NULL replacement unit 23 selects one transport stream from the multiplexed transport stream after demodulation (FIG. 2A) according to the control of the frame synchronization / control information separation unit 22. Here, the slot selection / NULL replacement unit 23 replaces packets other than the TS packets of the selected transport stream with NULL packets (shaded portions in the figure) to extract a single transport stream (FIG. 2 ( b)). Thereby, the selected single transport stream can be extracted without performing the speed conversion process.
The selected transport stream that has been replaced with the NULL packet is output to the MPEG decoder 28.
[0025]
The correction STC calculation unit 24 calculates a correction value ΔSTC for correcting the system clock reproduced by the system clock reproduction unit 27 described later. This is a system in which the system clock reproduction unit 27 reproduces the selected transport stream configured in the slot selection / NULL replacement unit 23 based on the PCR added in the selected transport stream when the MPEG decoder 28 decodes the selected transport stream. This is because the clock deviates from the clock necessary for actual decoding.
Therefore, the corrected STC calculation unit 24 converts 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 (reproduced into the original transport stream). A time difference from (FIG. 3B) is obtained for each TS packet, and is output to the system clock recovery unit 27 as a correction value ΔSTCi (i is a packet number within one frame). Since the slot position of each TS packet in the 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 in the frame length, T for the frame period (time), n (n <N) for the number of packet allocation slots of the selected transport stream, and i-th ( 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, correction values ΔSTC1 to ΔSTC5 when the transport stream of the broadcaster C is selected are shown.
[0026]
Next, referring to FIG. 4, the system clock recovery unit 27 includes an addition / subtraction circuit 51, a low-pass filter (LPF) 52, a voltage controlled oscillator (VCO) 53, and a counter 54.
The addition / subtraction circuit 51 receives the PCR added from the MPEG 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. ), And 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 system clock to be generated based on the error signal and outputs it to the counter 54. The counter 54 counts the system clock output from the VCO 53 and outputs it as a feedback to the adder / subtractor circuit 51.
Thereby, the system clock corresponding to each TS packet of the selected transport stream can be reproduced.
[0027]
Then, the MPEG decoder 28 decodes the input selected transport stream in accordance with the system clock reproduced by the system clock reproduction unit 27 and outputs it as video / audio.
[0028]
As described above, according to the receiving apparatus according to the first embodiment of the present invention, packets other than the TS packets 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 need for configuring the PLL circuit and the buffer memory on the receiving device side, thereby realizing a receiving device that is easy to configure and inexpensive.
[0029]
(Second Embodiment)
In the first embodiment, a case has been described in which a time lag caused by not performing speed conversion is corrected by controlling the system clock on the receiving device 2 side.
Next, in the second embodiment of the present invention, a transmission system (a TS multiplexing transmission device and a transmission device) that realizes an easy-to-configure and low-cost receiving device by adding a time lag to the PCR in advance on the transmitting device side. Receiving device).
[0030]
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 is configured by connecting a TS multiplexing transmitter 1 and a receiver 3 via a transmission line 13. The TS multiplexing transmission device 1 includes a plurality of TS multiplexing units 11 and a modulation unit 12. The receiving device 3 includes a demodulator 21, a frame synchronization / control information separator 22, a slot selection / NULL replacement unit 23, a system clock recovery unit 37, and an MPEG decoder 28.
Note that, 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.
[0031]
  First, the operation of the TS multiplexing transmitter 1 will be described.
  As described above, each broadcaster A to C generates a transport stream TS-A to TS-C of a program to be provided according to the MPEG2 standard (FIG. 1).4(Refer to (a) to (c)), and output to the multiple TS multiplexing unit 11 of the TS multiplexing transmission device 1.
  The multiple TS multiplexing unit 11 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 stream, and the number of slots in one frame. N multiplexed transport streams are generated (FIG. 1).4(See (d)). Here, the multiple TS multiplexing unit 11 obtains a time difference that varies due to speed conversion and multiplexing as a correction value ΔPCRi (i is a packet number within one frame) for each TS packet, Each value is rewritten to a value obtained by adding ΔPCRi to PCR. Specifically, the correction value ΔPCRi is defined as N for the number of slots in the frame length, T for the frame period (time), n (n <N) for the number of packet allocation slots of the target transport stream, and i in the frame. When the assigned slot position of the i th (i = 1 to n) is Pi, it is obtained according to the following equation (3).
    ΔPCRi = {(Pi−1) / N− (i−1) / n} × T (3)
[0032]
The modulation unit 12 performs predetermined modulation on the multiplexed transport stream after the PCR rewriting output from the multiple TS multiplexing unit 11, and then transmits the modulated transport stream to the reception device 3 via the transmission path 13.
[0033]
Next, the operation of the receiving device 3 will be described.
The demodulator 21 receives and demodulates the multiplexed transport stream transmitted via the transmission path 13. The frame synchronization / control information separation unit 22 performs frame synchronization of the multiplexed transport stream, separation / analysis of transmission control signals, and the like, and broadcasters A to C (that is, typically given from the CPU) (ie, from the broadcasters A to C). The slot selection / NULL replacement unit 23 is controlled in accordance with the selection instruction of the transport streams TS-A to TS-C).
[0034]
The slot selection / NULL replacement unit 23 selects one transport stream from the multiplexed transport stream after demodulation (see FIG. 2A) according to the control of the frame synchronization / control information separation unit 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 (see FIG. 2B). Thereby, the selected single transport stream can be extracted without performing the speed conversion process. The selected transport stream that has been replaced with the NULL packet is output to the MPEG decoder 28.
[0035]
The system clock recovery unit 37 has a configuration conventionally used. As shown in FIG. 6, the system clock recovery unit 37 includes a subtraction circuit 61, a low-pass filter (LPF) 52, a voltage-controlled oscillator (VCO) 53, and a counter 54. Prepare. The subtraction circuit 61 inputs the PCR added in the selected transport stream from the MPEG decoder 28 and the STC fed back from the counter 54, and calculates an error signal for each TS packet according to the following equation (4). To 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 system clock to be generated based on the error signal and outputs it to the counter 54. The counter 54 counts the system clock output from the VCO 53 and outputs it as a feedback to the subtraction circuit 61.
Thereby, the system clock corresponding to each TS packet of the selected transport stream can be reproduced.
[0036]
Then, the MPEG decoder 28 decodes the selected selected transport stream in accordance with the system clock reproduced by the system clock reproduction unit 37 and outputs it as video / audio.
[0037]
As described above, according to the transmission system according to the second embodiment of the present invention, the processing other than the TS packet of the selected transport stream is replaced with the NULL packet without performing the speed conversion performed on the receiving device side. Correspondingly, a time lag caused by not performing speed conversion on the transmitting device side is added in advance to the PCR to be transmitted.
This eliminates the need for configuring the PLL circuit and the buffer memory on the receiving device side, thereby realizing a receiving device that is easy to configure and inexpensive. In addition, 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 recovery unit on the receiving device side.
[0038]
(Third embodiment)
In the transmission apparatuses of the first and second embodiments, as shown in FIG. 2A, the transport streams TS-A to TS-C provided by the broadcasters A to C are transferred to the same transport. Multiplexing is performed by assigning slots in which TS packets of the stream are continuous. For this reason, the delay time of the TS packet is not constant on the receiving device side, and the reproduction processing speed of the selected transport stream cannot catch up or is not in time for the reproduction, and overflow / underflow occurs. There is a fear.
Therefore, in the third embodiment of the present invention, there is provided a TS multiplexing transmission apparatus that prevents the occurrence of overflow / underflow on the receiving apparatus side by multiplexing each TS packet by non-consecutive slot allocation.
[0039]
FIG. 7 is a block diagram showing a configuration of a TS multiplexing transmission apparatus according to the third embodiment of the present invention. In FIG. 7, a TS multiplexing transmission device 4 according to the third embodiment of the present invention includes a plurality of TS multiplexing units 41 and a modulation unit 12.
In the TS multiplexing transmission device 4 of the third embodiment, the same components as those of the TS multiplexing transmission device 1 according to the second embodiment are denoted by the same reference numerals. In addition, as the reception device corresponding to the TS multiplexing transmission device 4 according to the third embodiment, any of the reception devices 2 and 3 described in the first or second embodiment can be used. .
8 and 10 are diagrams illustrating an example of multiplexing performed by the multiple TS multiplexing unit 41 in FIG. 9 and FIG. 11 respectively show the receiving apparatuses 2 and 3 for the multiplexed transport streams output by the TS multiplexing transmission apparatus 4 according to the third embodiment of the present invention according to the multiplexing shown in FIG. 8 and FIG. It is a figure which shows an example of the transport stream selection process which the slot selection / NULL replacement | exchange part 23 performs.
[0040]
As described above, the broadcasters A to C respectively generate the transport streams TS-A to TS-C of the programs to be provided according to the MPEG2 standard (FIGS. 8A to 8C and 10A). To (c)), and outputs to the multiple TS multiplexer 41 of the TS multiplexing transmitter 4.
The multiple TS multiplexing unit 41 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 stream, and the number of slots in one frame N multiplexed transport streams are generated. Here, the multiple TS multiplexing unit 41 performs slot allocation by distributing the TS packets of the transport streams TS-A to TS-C so that they are not all continuous.
As a method of assigning slots by distributing the TS packets, several methods are conceivable, and two typical methods will be specifically described below as an example.
[0041]
First, the first method will be described with reference to FIGS. 8 and 9.
In the first method, when the i-th (i = 1 to n) allocation slot position in the frame is Pi, slot allocation is performed according to the following equation (5) on the assumption that the following conditions are satisfied. . Here, floor (x) is a function that truncates the value x after the decimal point.
Pi = floor {N × (i−1) / n} +1 (5)
[conditions]
Processing is performed from a transport stream with a large number of assigned slots.
If the calculated Pi is already assigned, assign it to P (i + 1).
[0042]
When the slot allocation of each TS packet shown in FIGS. 8A to 8C is performed according to the above equation (5), the frame shown in FIG. 8D is configured.
Specifically, the processing starts from the transport stream TS-C having a large number of assigned 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
[0043]
Next, the second method will be described with reference to FIGS. 10 and 11.
In the second method, the total number of transport streams to be processed is S, the order of processing the transport streams is r (r = 1, 2,...), And the i-th (i = 1 to n) in the frame. When the allocation temporary slot position is Pi, slot allocation is performed according to the following equation (6) on the assumption that the following conditions are obeyed. Here, floor (x) is a function that truncates the value x after the decimal point.
Pi = floor {N × (i−1) / n}
+ Floor {(r−1) × N / S} +1 (6)
[conditions]
Processing is performed from a transport stream with a large number of assigned slots.
When the obtained Pi exceeds the number N of slots in one frame, it is assigned as Pi ← (N−Pi).
If the calculated Pi is already assigned, assign it to P (i + 1).
For each transport stream, rearrange the TS packets assigned to each slot in time order.
[0044]
When the slot assignment of each TS packet shown in FIGS. 10A to 10C is performed according to the above equation (6), the frame shown in FIG. 10D is configured.
Specifically, the processing starts from the transport stream TS-C having a large number of assigned slots, and the temporary slot position of each TS packet is 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 (allocated) → 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
For the transport streams TS-B and TS-A, the TS packets at the respective slot positions are rearranged in time order.
[0045]
As described above, in the first method, the TS packets of all the transport streams are assigned from the first slot, so that the transport stream to be processed later (for example, TS-A) assigns TS packets. Although the position tends to be shifted to the rear of the frame, that is, the delay time (jitter) tends to increase, there is an advantage that it is not necessary to rearrange the positions of the TS packets in time order. On the other hand, in the second method, after the slot positions are allocated, it is necessary to rearrange the positions of the TS packets in time order. However, the transport stream to be processed later may be allocated to the entire frame to some extent. There is an advantage that it is possible (average delay time is reduced).
Also, in both the first and second methods, the slot assignment does not change unless the number of assigned slots in each transport stream changes. Therefore, even when a transmission error occurs in a transmission control signal (slot information used by each transport stream) transmitted from the transmission apparatus, the reception apparatus uses the immediately preceding transmission control signal to transmit the transport stream. There is an advantage that the selection process can be continued accurately.
[0046]
  In the first and second methods described above, a case has been described in which processing is performed from a transport stream having a large number of allocated slots as a condition. However, even if processing is performed from a transport stream having a small number of allocated slots, the slot position is determined. Can be distributed and assigned. However, configure on the receiving device sideOverflow / underflow preventionBuffer memory(This is separate from the speed conversion process.)In consideration of the fact that (delay time amount × transmission rate) is required as the capacity of the packet, and that the delay time increases as the transport stream for which slot assignment processing is performed later as described above, the same delay time amount may be used. For example, a transport stream with a smaller number of assigned slots (slower transmission speed) requires less buffer memory capacity for processing.
  Therefore, when the transport stream is an MPEG video / audio signal reproduced at a constant rate, the number of assigned slots is large (the transmission speed is high) in order to prevent the occurrence of overflow / underflow on the receiving apparatus side. It is preferable to perform slot allocation processing in order from the transport stream.
[0047]
Here, as a next-generation transmission method, the number of slots in one frame is set to “53”, and the first slot in the frame is configured with a frame header for storing transmission control information (frame synchronization signal, TS packet arrangement information, etc.). There is a multi-TS transmission system for digital CATV that is currently being standardized. In such a transmission method, when the slot allocation method provided by the present invention is applied, the following processing may be performed.
The total number of slots assigned to each transport stream is set to be within “52”, and the slot assignment process described above is first performed. Next, the position of the slot to which no TS packet is assigned in this process is extracted, and the TS packets at all slot positions are rotated or a part of the slots so that the first slot of the frame becomes the frame header according to the position. Slide the TS packets at the position to rearrange them. For example, as a rotation method, when the 10th slot position is extracted, the TS packet at the 11th slot position is set at the second slot position, and the TS packet at the 12th slot position is set at the 3rd slot position. ..., and rearranges the TS packet at the ninth slot position to the 53rd slot position. As a sliding method, when the 10th slot position is extracted, the TS packet at the 1st slot position is set at the 2nd slot position, and the TS packet at the 2nd slot position is set at the 3rd slot position. ..., the TS packets at the ninth slot position are rearranged to the tenth slot position (in this case, the TS packets at the eleventh to 53rd slot positions are not rearranged).
Note that the correspondence between each slot position and the TS packet based on this slot allocation processing is stored as TS packet arrangement information in the frame header.
[0048]
When the receiving apparatus is the receiving apparatus 3 described in the second embodiment, the multi-TS multiplexing unit 41 then completes the multi-TS multiplexing of the second embodiment after completing the slot allocation process. Similarly to the unit 11, the time difference that varies due to speed conversion and multiplexing is obtained as a correction value ΔPCRi for each TS packet, and rewritten to a value obtained by adding ΔPCRi to the current PCR.
On the other hand, when the receiving device is the receiving device 2 described in the first embodiment, the multiple TS multiplexing unit 41 does not rewrite the PCR.
[0049]
The modulation unit 12 performs a predetermined modulation on the multiplexed transport stream after the distributed slot assignment (and PCR rewrite) processing output from the multiple TS multiplexing unit 41, and then receives the modulated signal via the transmission path 13. 2 and 3 are transmitted.
Then, the slot selection / NULL replacement unit 23 of the receiving apparatuses 2 and 3 performs the processing described in the first and second embodiments, thereby receiving the multiplexed transport stream (FIG. 9A or FIG. 11 (a)), each frame as shown in FIG. 9B or FIG. 11B is configured.
[0050]
As described above, according to the TS multiplexing transmission device according to the third embodiment of the present invention, in addition to the processing of the first and second embodiments, all TS packets of the same transport stream are not continuous. In this way, multiplexing is performed by slot allocation.
Thereby, in addition to the effects of the first and second embodiments, the occurrence of overflow / underflow on the receiving device side can be prevented.
[0051]
In the first to third embodiments, the speed conversion of TS packets of the selected transport stream is not performed on the receiving device side.
Therefore, by utilizing this fact, program arrangement information (for example, BS digital) related to all transport stream tuning is included in only one of the transport streams provided by a plurality of broadcasters in the transmission apparatus. TS packet in which a specific PID (packet identifier) giving the program arrangement information is stored together with the selected transport stream in the receiving apparatus. It is also possible to extract a single transport stream (regardless of selection / non-selection of the transport stream). FIG. 12 shows an example in which the transport stream TS-B is selected by the slot selection / NULL replacement unit 23 when a specific PID is stored in the TS packet “A2”.
This eliminates the need for the transmission apparatus side to transmit the program arrangement information in all transport streams, thereby effectively utilizing (saving) transmission band resources.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a receiving apparatus 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 of FIG.
FIG. 3 is a diagram illustrating an example of ΔSTC calculated by a corrected STC calculation unit 24 in FIG.
4 is a block diagram showing a detailed configuration of a system clock recovery unit 27 in FIG. 1. FIG.
FIG. 5 is a block diagram showing a configuration of a transmission system according to a second embodiment of the present invention.
6 is a block diagram showing a detailed configuration of a system clock recovery unit 37 in FIG. 5. FIG.
FIG. 7 is a block diagram showing 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 a plurality of TS multiplexing units 41 in FIG.
9 is a diagram illustrating an example of a transport stream selection process performed by the slot selection / NULL replacement unit 23 of FIGS. 1 and 5 for the multiplexed transport stream output in accordance with the multiplexing shown in FIG.
10 is a diagram illustrating an example of multiplexing performed by a plurality of TS multiplexing units 41 in FIG.
11 is a diagram illustrating an example of a transport stream selection process performed by the slot selection / NULL replacement unit 23 of FIGS. 1 and 5 for the multiplexed transport stream output in accordance with the multiplexing shown in FIG.
12 is a diagram illustrating an example of a transport stream selection process performed by the slot selection / NULL replacement unit 23 of FIGS. 1 and 5. FIG.
FIG. 13 is a block diagram illustrating an example of a configuration of a conventional digital broadcasting system.
14 is a diagram illustrating an example of multiplexing performed by the transmission 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 multiplexing transmission apparatus
2,3,200 ... receiver
11, 41, 101... Multiple TS multiplexing unit
12, 102 ... modulation section
13, 103 ... transmission path
21, 201 ... demodulator
22, 202... Frame synchronization / control information separation unit
23 ... Slot selection / NULL replacement unit
24. Correction STC calculation unit
27, 37, 207 ... system clock recovery 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 / writing unit
204 ... PLL circuit
205: Buffer memory
206 ... Read-out circuit

Claims (6)

A receiving device for receiving a multiplexed transport stream that is multiplexed with a predetermined number of slots assigned to each of a plurality of transport streams,
From the received multiplexed transport stream, the TS packet at the slot position of the transport stream to be selected is extracted, and the slot selection / generation to generate the transport stream by replacing the slot position of the transport stream not to be selected with a NULL packet NULL replacement means;
The frame period of the multiplexed transport stream is T, the number of slots of the frame length is N, the number of assigned slots of the transport stream to be selected is n (n <N), and the i-th (i = If the assigned slot position of 1 to n) is Pi,
ΔSTCi = {(i−1) / n− (Pi−1) / N} × T
And a correction STC calculation means for calculating the correction value ΔSTCi, respectively.
A system that reproduces a system clock that gives a decoding timing based on a value obtained by subtracting the correction value ΔSTCi from a PCR (program clock reference reference value) added to a transport stream output by the slot selection / NULL replacement means A receiving device comprising clock recovery means. When program arrangement information related to all transport stream channel selections is transmitted by any one of the plurality of transport streams,
2. The receiving apparatus according to claim 1, wherein the slot selection / NULL replacement unit further extracts a TS packet storing a specific PID (packet identifier) giving the program arrangement information. A TS multiplexing transmission apparatus that generates and transmits a multiplexed transport stream that is multiplexed by assigning a predetermined number of slots for each of a plurality of transport streams,
A plurality of TS multiplexing means for generating a multiplexed transport stream by converting and multiplexing each of the plurality of transport streams in units of TS packets constituting the stream;
The frame period of the multiplexed transport stream is T, the number of slots of the frame length is N, the number of assigned slots of the target transport stream is n (n <N), and the i-th (i = 1) in the frame ˜n) where the assigned slot position is Pi,
ΔPCRi = {(Pi−1) / N− (i−1) / n} × T
And a PCR correction means for calculating a correction value ΔPCRi and adding the correction value ΔPCRi to the current PCR. Wherein the plurality TS multiplexing means, for each of the plurality of transport streams, TS packets constituting the transport stream, and performs slot assignment by dispersing all to not continuously, according to claim 3 TS multiplexing transmitter. The TS multiplexing transmission apparatus according to claim 4 , wherein the plurality of TS multiplexing means performs TS packet allocation processing from a transport stream having a large number of allocated slots. A transmission system that performs transmission and reception using a multiplexed transport stream that is multiplexed by assigning a predetermined number of slots for a plurality of transport streams,
A plurality of TS multiplexing means for generating a multiplexed transport stream by converting and multiplexing each of the plurality of transport streams in units of TS packets constituting the stream;
The frame period of the multiplexed transport stream is T, the number of slots of the frame length is N, the number of assigned slots of the target transport stream is n (n <N), and the i-th (i = 1) in the frame ˜n) where the assigned slot position is Pi,
ΔPCRi = {(Pi−1) / N− (i−1) / n} × T
And a PCR correction means for calculating and adding the correction value ΔPCRi to the current PCR, respectively,
From the received multiplexed transport stream, the TS packet at the slot position of the transport stream to be selected is extracted, and the slot selection / generation to generate the transport stream by replacing the slot position of the transport stream not to be selected with a NULL packet NULL replacement means;
A transmission comprising: a receiving device comprising: a system clock recovery means for recovering a system clock for giving a decoding timing based on the PCR added to the transport stream output by the slot selection / NULL replacement means system.

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