JP2004007541A - Data multiplexing method and multiplexed data decoding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for multiplexing, transmitting and decoding image and audio data capable of surely decoding the data even when contents of the transmitted data are changed by reducing jitter of a clock signal. <P>SOLUTION: The data multiplexing method is characterized in that when a first packet stream multiplexing a packet including digital data of a kind or more with a packet including a reference time signal of the decoding apparatus is received: a second packet stream multiplexing a packet including digital data of a kind or more with a packet including the reference time signal of the decoding apparatus is received; and a third packet stream resulting from multiplexing the first packet stream with the second packet stream is outputted; and when the packet including the reference time signal in the first packet stream and the packet including the reference time signal in the second packet stream are received within a prescribed time, the reference time signal is deleted from the packet including the reference time signal in the first packet stream. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a data multiplexing method, a data transmission method, a decoding method for decoding multiplexed data, and an apparatus for multiplexing and transmitting digital images, sounds, digital data, and the like.
[0002]
[Prior art]
With the advance of compression technology, digital image and audio services have been partially put to practical use in broadcasting and CATV in recent years. When transmitting digital images, audio, and other data, it is also an important issue how to multiplex the data together with the compression technology.
[0003]
Hereinafter, an MPEG data multiplexing method, which is an international standard of the above-described data multiplexing method, and a multiplexed data decoding device for decoding multiplexed data will be described with reference to the drawings.
[0004]
FIGS. 11, 12, and 13 are explanatory diagrams of a conventional MPEG2 data multiplexing method. FIG. 14 is a block diagram of a multiplexed data decoding device for decoding data multiplexed by the MPEG2 data multiplexing method. In FIG. 14, reference numeral 141 denotes a separation unit which includes a buffer 1411 and a CPU 1412. Reference numeral 142 denotes a clock control unit; 143, an image decoder; and 144, an audio decoder. FIG. 15 is a flowchart illustrating the operation of the CPU 1412 of the separation unit.
[0005]
The operation of the conventional MPEG2 data multiplexing method and multiplexed data decoding device configured as described above will be described below.
[0006]
The image data and the audio data are compression-coded for each fixed number of samples such as a frame for an image and 1024 for an audio (the audio is also called a frame in MPEG), and one frame or a plurality of frames are collectively collected. Create a packet called a PES packet. FIG. 13 shows an outline of the format of the PES packet. A header is attached to the PES packet, and the header includes a stream ID indicating whether the subsequent data area is image data, audio data, or other data, or special reproduction. For example, information such as a trick mode flag indicating that the data is data for the second mode is included. The PES packet is divided into a plurality of TS packets having a length of 188 bytes and transmitted.
[0007]
FIG. 11 shows the outline of the format of a TS packet. Each TS packet has a packet-specific number called PID. The PID is not different for each TS packet, but the same PES packet has the same PID. As shown in FIG. 11 (b), the TS packet transmits information used for separating data or multiplexed data called an adaptation field, following the header. Since the length of the adaptation field depends on the information to be transmitted, if the length is short, data can be transmitted following the adaptation field. The PID of the TS packet is sent as a part of the header as shown in FIG. FIG. 11D is a diagram showing a part of the contents of the adaptation field, and FIG. 11E is an explanatory diagram showing a part of the contents of the option field as a part of the adaptation field. In the adaptation field, a reference time clock PCR necessary for decoding can be transmitted as an option field as shown in FIG. In MPEG2, the clock frequency of the multiplexing device and the demultiplexing device is set to 27 MHz, and a numerical value obtained by counting the clock of the multiplexing device at 27 MHz, PCR, is transmitted in order to prevent buffer overflow and underflow. The separating device reproduces a clock synchronized with the multiplexing device from the received PCR. This PCR need not always be sent, and is sent at intervals necessary for synchronizing the separation device, for example, approximately once every 0.7 seconds. Therefore, the adaptation field has a structure that does not need to be transmitted as an option field. Also, when a different program is sent, encoding is often performed by a different image encoder, so that the reference clock is generally different. When different PCRs are transmitted with the same program number or the like, the discontinuity flag in the adaptation field is set to 1 to notify the separation device that a discontinuous point of the PCR exists.
[0008]
In the data area of the TS packet, in addition to the PES packet shown in FIG. 11, program selection information called PSI can be sent. FIG. 12 shows a structure of a program table PMT which is one of the PSIs. The PMT is multiplexed with a program number indicating the number of the program to be transmitted and the PIDs of the PCR, image data PES, audio data PES, and data PES packets required for reproducing the program.
[0009]
FIG. 14 shows an example of a conventional multiplexed data decoding apparatus that receives data multiplexed as described above and reproduces the data. The received multiplexed data is stored in the buffer 1411 first. The CPU 1412 operates based on the flowchart shown in FIG. 15, and searches for the PMT of the program number set from the outside from the first transmitted data. When the PMT is detected, the PMT of the PCR, image data PES, audio data PES, and data PES packet is extracted from the PMT. Next, by looking at the PID of the TS packet in the received data, a TS packet necessary for reproducing the program is extracted. Among the TS packets, the packet including the PCR is sent to the clock control unit 142 to reproduce the reference clock required for the image and audio decoder. Image and audio packets of the TS packets are sent to the respective decoders 143 and 144. The decoding unit can use the reproduced reference clock to decode the image and audio data and decompress and reproduce the program (for example, ISO / IEC JTC1 / SC29 N801, &quot; ISO / IEC CD 13818-1: Information technology-Generic). coding of moving pictures and associated audio: Systems &quot;, 1994.11).
[0010]
[Problems to be solved by the invention]
However, various problems occur in the decoding apparatus only with the above configuration. First, when multiplexing TS packets of a plurality of programs, there is a possibility that TS packets having the reference clock PCR may collide during packet multiplexing, and as a result, the interval between PCR packets fluctuates, resulting in jitter. In the decoding device, the PLL is configured to reproduce the reference clock. However, if the interval of the PCR becomes a certain value or more, the jitter cannot be absorbed, and the clock cannot be reproduced.
[0011]
Also, the PCR becomes discontinuous at the beginning of the program or when the program is switched, but before the non-continuous packet arrives, the discontinuity flag in FIG. There is no. Therefore, in the worst case, the next discontinuous PCR arrives without the discontinuity flag, and the decoding device tries to synchronize with a completely different PCR, so that the operation becomes unstable.
[0012]
Furthermore, when the frame frequency of the image or the sampling frequency of the audio changes, the output clock from the decoding device also needs to be changed, but in general, a certain time is required to establish synchronization, and data with different sampling frequencies is required. , The synchronization system cannot be established and the output may be disturbed.
[0013]
On the other hand, in FIG. 13, a trick mode flag is included in the PES header, and commands such as fast-forward and stationary can be sent together with the PES packet. However, there is no clear definition of the operation of the decoding device, and there is no guarantee of reliable operation.
[0014]
In view of the above problems, the present invention provides a data multiplexing method, a data transmission method, a multiplexed data transmission method, a multiplexed data decoding method, and a multiplexed data decoding device which ensure the operation of a multiplexed data decoding device during normal or special reproduction. To provide.
[0015]
[Means for Solving the Problems]
In order to solve the above problem, a data multiplexing method according to the present invention comprises: a first packet sequence in which a packet including one or more types of digital data and a packet including a reference time signal of a decoding device are input; A second packet sequence obtained by multiplexing the packet including the digital data and the packet including the reference time signal of the decoding device is input, and the first packet sequence and the second packet sequence are multiplexed to form a third packet sequence. When the packet including the reference time signal in the first packet sequence and the packet including the reference time signal in the second packet sequence are input within a predetermined time, Deleting the reference time signal from the packet including the reference time signal in the first packet sequence, or a data packet including one or more types of digital data, and the contents of the packet When generating a multiplexed packet by multiplexing a table packet including a table indicating a packet number and a packet number, when changing the contents of the table packet, the table packet is transmitted before the data packet corresponding to the changed table packet is transmitted. When the instruction signal indicating the change and the changed table packet are multiplexed into the multiplexed packet, or when the packet including one or more types of digital data and the packet including the reference time signal of the decoding device are multiplexed, the digital A packet of a reference time signal multiplexed before a packet containing data, or when the content of digital data is discontinuous, before a packet containing discontinuous digital data, indicates that the reference time signal is not continuous. A reference time signal discontinuity flag is added, and the flag is also multiplexed. It is.
[0016]
In the data multiplexing method of the present invention, when a special reproduction is performed using a plurality of packets including audio data, image data, and other digital data, a packet including an image or audio data is specially composed of only data of the same frame. A special reproduction packet is formed and the special reproduction packet is transmitted. Further, the multiplexed data decoding method of the present invention decodes a packet containing digital image data compressed using frame or intra-field compression encoding and frame or inter-field compression encoding, and uses the decoded data to perform arbitrary decoding. When a still image is received in a frame or a field, when a still command signal is received, an image obtained by decoding image data that has been compression-coded in the immediately preceding or succeeding frame or field is displayed as a still image, or compressed digital image data is displayed. When decoding a packet to which a flag indicating the decoding or display time is added, and stationary in an arbitrary frame or field using the decoded data, at the time of receiving a still command signal, the time immediately before or immediately after Indicated the decoding or display time of accessible image data Storing the lugs, at rest resume sending flag showing decoding or display time of the image data that can be the access multiplexer, is to resume decoding from the accessible image data.
[0017]
(Action)
According to the present invention, since the interval between the reference signals PCR is equal to or less than a certain value by the above-described configuration, there is no problem in clock reproduction. Further, when the program is changed, the PMT, PCR, etc. are transmitted prior to the data of the changed contents, so that the operation of the decoding device is ensured. Further, at the time of trick play, data of only the same picture is formed into a PES packet and transmitted to the decoding device, so that the image is not interrupted in the middle. Even when an image is displayed still, it can be stopped by an intra-frame coded picture, and the time information of the still picture can be transmitted to the transmission device to retransmit from the still picture image data, so that a continuous image can be reproduced even after the end of the still image. It becomes.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a data multiplexing method according to the first embodiment of the present invention will be described with reference to the drawings.
[0019]
FIG. 1 is a block diagram of a data multiplexing apparatus according to a first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a first data multiplexing unit, which comprises a clock generation circuit 11, a CPU 12, and a buffer 13. 2 is a second data multiplexing unit, 3 is a second data multiplexing unit, and both have the same configuration as the first data multiplexing unit. FIG. 2 is an explanatory diagram showing a part of the operation of the CPU 32 in the third data multiplexing unit.
[0020]
A data multiplexing method in the data multiplexing apparatus configured as described above will be described with reference to FIGS.
[0021]
Image data, audio data, and other data to be multiplexed are compression-encoded by an image encoder 14, an audio encoder 15, and a data encoder 16, respectively, and are converted into PES packets as shown in FIG. Enter in the section. The first and second data multiplexing units 1 and 2 perform multiplexing while converting PES packets into TS packets so that synchronization of image, audio, and data and buffer overflow and underflow in the multiplex data decoder do not occur. . The outputs of the data multiplexing unit 1 and the data multiplexing unit 2 are further multiplexed by the data multiplexing unit 3. This assumes, for example, a case where the outputs of the data multiplexing units 1 and 2 are each 4 Mbps and both are transmitted to an 8 Mbps transmission line. As shown in FIG. 2, the data multiplexing unit 3 inputs TS packets from the data multiplexing unit 1 and the data multiplexing unit 2 at 210 and 211, and multiplexes and outputs each input, for example, alternately. At that time, a problem arises when both packets include the reference clock PCR required by the multiplex data decoding device at the same time. In order to facilitate the design of the multiplex data decoding device, it is desirable that the fluctuation of the reference clock PCR be suppressed to a certain fixed value or less, and in the example cited in the conventional example, it is 30 ppm or less. However, when the TS packets of the multiplexing units 1 and 2 are input to the data multiplexing unit 3 at the same time, a shift of one TS packet occurs due to the multiplexing, and as a result, the PCR fluctuates. Therefore, in the present embodiment, the reference clock PCR is frequently inserted in the multiplexed data in advance, and when a collision occurs, the PCR field included in the TS packet on the input side of the multiplexing unit 1 as shown in the flowcharts 212 and 215 of FIG. Will be erased. The PCR field is optional and erasing it has no effect. Although the interval between the packets including the PCR is slightly extended, since the packet is frequently inserted in advance, the operation of the multiplex data decoding device is not hindered.
[0022]
As described above, according to this embodiment, data multiplexing that does not adversely affect the reference clock PCR of the multiplexed data decoding device can be realized.
[0023]
FIG. 3 is an explanatory diagram of a data multiplexing method according to the second embodiment of the present invention, and FIG. 4 is an explanatory diagram of a multiplexed data decoding method. 3 shows the operation of the CPU 12 of the first data multiplexing unit 1 in FIG. FIG. 4 is an explanatory diagram showing the operation of the CPU 1411 of the multiplexed data decoding device 141 in FIG. This will be described below with reference to FIGS.
[0024]
At the time of normal operation, the data multiplexing unit 1 repeats the operation of transmitting PMT and PCR at appropriate timing, and further converts TS of image, audio, and data PES packets at appropriate timing, and multiplexes and transmits.
[0025]
On the other hand, at the start of the program, since the multiplex data decoding device is not synchronized with the multiplex device, it is necessary to send a packet including the reference time PCR. When a PCR packet is sent, the decoding device attempts synchronization based on the sent PCR. At the start of the program, it takes time to synchronize because a PCR completely unrelated to the decoding device is sent. Therefore, a PCR discontinuity flag indicating that the PCR is discontinuous is set to 1 as indicated by 319 in FIG. When the decoding device detects that the discontinuity flag is 1, it does not attempt to synchronize with the transmitted PCR, but sets the transmitted PCR value and waits for the next PCR. Therefore, the time until synchronization is shortened. The above operation is effective not only when the program is started but also when the reference time PCR is changed due to a change in the contents.
[0026]
Next, at the start of the program, it is necessary to send a PMT indicating the relationship between the program and the PID. At this time, as shown at 321 in FIG. 3, the validity flag of the PMT is first set to 0, and a table based on the new packet number PID is created (322). If the validity flag of the PMT is 0, the multiplexed data decoding device invalidates the PMT and generally does not use the PMT. Next, when a PMT whose valid flag is 1 arrives, decryption is performed using the PMT. In the MPEG2 standard of the prior art, there is no clear definition of program change and how to use the PMT valid flag. Therefore, it is possible to send a different PMT while the PMT valid flag is set to 1. However, a general decoding device performs a series of operations such as changing the PMT, obtaining a PID of a TS packet necessary for decoding from the changed PMT, and starting extraction of TS packets having a desired PID from transmission data. Requires a certain amount of time. As a result, the packet immediately after receiving the changed PMT cannot be accurately extracted, and some data is lost, so that the image and the sound may be interrupted for a moment. Therefore, in the present invention, before sending a new PMT, that is, at the start of a program or when the contents of a program are changed, the PMT valid flag 0 is always added and the PMT corresponding to the new contents is sent.
[0027]
When receiving the PMT having the valid flag 0 as shown in the flowcharts 46 and 47 of FIG. 4, the multiplexed data decoding device obtains the necessary PID from the PMT, and has the PID necessary for decoding at the start of the program. It prepares to extract the extracted packet, that is, updates the PMT, and then starts the extraction from the PID following the PMT having the valid flag 1. When the contents of the program change in the middle, when a PMT having a valid flag 0 is received, the extraction of the currently valid PID is continued, the PMT is updated with a new PMT, and then the valid flag 1 is provided. The extraction of the TS packet having the PID corresponding to the new content is started from the PID following the PMT.
[0028]
As described above, by transmitting the PMT having the valid flag 0 before the actually valid PMT, even if the decoding device has a delay, there is no omission of the PID extraction, and the image and the sound can be reproduced without interruption. Become.
[0029]
The frame frequency of the image and the sampling frequency of the audio are the frequencies that determine the output frequency and operation of the decoding device, and the base clocks for these are generally generated from the received reference clock PCR. The emphasis characteristics of voice also change the output voice, and the characteristics themselves need to be set, and changing these settings requires a certain amount of time. Therefore, if data with these characteristics changed is continuously transmitted, it becomes impossible to accurately decode the data of the received packet in the time required for the setting. Therefore, in the present invention, as shown by 323, 324, 325, 326, 327, and 328 in FIG. 3, before transmitting the changing data, the frame frequency and the sound of the changed image are stored in an area called a PMT descriptor. Describes the sampling frequency or emphasis characteristics and sends it out. By transmitting the data as described above, the decoding device can change the clock or the characteristics before receiving the actual data, so that normal decoding can be performed even when the changed data is received. .
[0030]
FIGS. 5 and 6 are explanatory diagrams showing a data multiplexing method according to the third embodiment of the present invention. Hereinafter, description will be made with reference to FIGS.
[0031]
As shown in FIG. 5A, a PES packet of an image may include a plurality of pictures in one packet. Here, a picture indicates a frame or a field in MPEG image compression. Whether it is a frame or a field depends on the compression encoding method. In FIG. 5A, data of two pictures is included in the same packet. When performing special reproduction such as fast-forward, slow-motion, and still, as shown in FIG. 13, a trick mode flag in the PES header that informs the data decoding device of an operation such as fast-forward is set and transmitted together with image data. Reading these flags, the decoding device performs buffer control and screen control. Normally, these special reproduction operations are controlled on a frame or field basis, that is, on a picture basis. However, if data of one picture or more is mixed in the PES packet for FIG. 5A, it is necessary to perform an operation of placing a buffer in the decoding device and reconstructing data for one picture from the two PES packets. Therefore, in the present invention, a PES packet as shown in FIG. 5A is reconstructed into one picture and one packet before transmission as shown in FIG. 5B, and then transmitted. FIG. 6 is a flowchart for realizing the above operation, which is used, for example, as an algorithm of the CPU 12 of the first data multiplexing unit 1 in FIG. As for the operation of the CPU, when a signal requesting special reproduction is input, it is first checked at 64 whether or not one picture is composed of one PES packet. Otherwise, the position of the PES header is determined at 66, 67, 68. Is updated immediately before the picture header.
[0032]
By the above operation, only the same picture is included in one packet, and the correspondence between the trick mode flag and the picture data becomes clear, and at the same time, the operation of the complicated decoding device or the hardware becomes unnecessary.
[0033]
Although only the image data has been described in the above embodiment, the same operation is effective for audio data. However, in the case of audio data, the frame is not a picture but a unit indicating a unit of compression encoding.
[0034]
FIG. 7 is an explanatory diagram showing a multiplexed data decoding method according to the fourth embodiment of the present invention, and FIG. 8 is an explanatory diagram showing the contents of multiplexed data. Hereinafter, description will be made with reference to FIGS.
[0035]
Now, as shown in FIG. 8, the image data of the multiplexed data is an intra-frame coded picture (I picture), a forward predicted inter-frame coded picture (P picture), and a bidirectional predicted inter-frame coded picture (B picture). It is assumed that it is composed of An I picture can be decoded by itself, whereas a P picture cannot be decoded without an I and P picture transmitted before it, and a B picture cannot be decoded without an I and P picture transmitted before it. In FIG. 8, transmission is performed in the order of I1, B0, P3, and B2 following the B picture. Decoding is performed in the transmission order, but the display is reversed as B0, I1, B2, P3 when the first B picture is ignored. Also, when performing image compression encoding by the above-described method, it is generally known that the image quality of I and P pictures is better and the image quality of B pictures is slightly worse to improve the overall image quality.
[0036]
When an image is stopped during special reproduction, an image with higher image quality can be obtained by stopping the image other than the B picture for the above reason. Also, it is desirable to start from the same frame when releasing the stillness. When transmitting such data, it is common to make a random access possible by inserting a sequence header before an I picture that can be decoded by itself. Therefore, access from the I picture, that is, resumption of stillness, is relatively easy.
[0037]
FIG. 7 shows the above operation in a flowchart of the CPU 1412 of the data decoding device in FIG. In FIG. 7, at 72, the DTS (decode time stamp: the decode time represented by the reference time PCR) of the I picture is always stored. When a still signal is input, it is confirmed at 76 whether or not an I picture has been displayed. At the time when the I picture has been displayed, updating of the image display is stopped and the image is stopped. Thereafter, at 80, the DTS of the last stored I-picture, that is, the I-picture currently displayed still, is sent to the data multiplexing device. The multiplexing device determines the I-picture currently displayed in a still state based on the DTS sent from the decoding device, and starts transmission from the I-picture corresponding to the DTS at the end of the stillness. In the decoding device, a B picture between the first P pictures following an I picture cannot be decoded without an I or P picture preceding the I picture, so the B picture is not decoded and displayed. Start by decoding and displaying. With the above operation, it is possible to continuously reproduce the still picture at the end of the still picture without interruption from the still picture.
[0038]
FIG. 9 is an explanatory diagram showing a multiplexed data decoding method according to the fifth embodiment of the present invention. The difference from the fourth embodiment is that the display update is stopped at 95 when a still signal is input at 92 and the currently displayed image is continuously displayed as it is at 95. At the end of the stationary state, the currently received data is analyzed, and decoding is restarted from the I picture. According to the present embodiment, it is impossible to reproduce from the same picture, but there is no need to send a DTS to the data multiplexing apparatus, and the entire system can be configured at low cost.
[0039]
In the above-described embodiment, the still image is stopped at the currently displayed image. However, the present invention is not limited to this, and the still image may be stopped at the I picture as in the fourth embodiment.
[0040]
FIG. 10 is an explanatory diagram showing a multiplexed data decoding method according to the sixth embodiment of the present invention. This embodiment is different from the fourth and fifth embodiments in that the input is stopped as indicated by 105 instead of stopping the display when a still signal is input. Generally, the image decoder continues to display the last displayable image as it is when there is no input. Therefore, by stopping the input of the decoding device, the image is frozen. When the last image of the input is an I or P picture, it is desirable to use the picture as a still picture because the picture quality is good. However, a B picture following the I or P in the transmission order, ie, the display order , There is no B picture before the I or P picture, so that the last I or P picture of the input is not displayed, and the B picture sent before that is stopped. In the present embodiment, when the last input picture is I or P as in 106, 107, and 108 in FIG. 10, the I or P picture is displayed ignoring the DTS indicating the decoding time and the PTS indicating the display time. To be stationary.
[0041]
With the above operation, stationary special reproduction can be realized by changing only the input of the decoding device without adding new hardware to the display system.
[0042]
【The invention's effect】
As described above, the present invention suppresses the jitter of the reference time PCR to a certain value or less, and thus does not hinder the operation of the decoding device. Further, when the program is changed, the PMT, PCR, etc. are transmitted prior to the data of the changed contents, so that the operation of the decoding device is ensured. Further, at the time of trick play, data of only the same picture is formed into a PES packet and transmitted to the decoding device, so that the image is not interrupted in the middle. Even when the image is displayed still, it can be stopped with the intra-frame coded picture, and the time information of the still picture can be sent to the transmission device to retransmit from the still picture image data. It becomes.
[Brief description of the drawings]
FIG. 1 is a block diagram of a data multiplexing apparatus according to a first embodiment of the present invention.
FIG. 2 is an explanatory diagram showing a part of the operation of a CPU 32 in a third data multiplexing unit according to the first embodiment of the present invention.
FIG. 3 is an explanatory diagram of a data multiplexing method according to a second embodiment of the present invention.
FIG. 4 is an explanatory diagram of a multiplexed data decoding method according to a second embodiment of the present invention;
FIG. 5 is an explanatory diagram showing a data multiplexing method according to a third embodiment of the present invention.
FIG. 6 is an explanatory diagram showing a data multiplexing method according to a third embodiment of the present invention.
FIG. 7 is an explanatory diagram showing a multiplexed data decoding method according to a fourth embodiment of the present invention.
FIG. 8 is an explanatory diagram showing the contents of multiplexed data in a fourth embodiment of the present invention.
FIG. 9 is an explanatory diagram showing a multiplexed data decoding method according to a fifth embodiment of the present invention.
FIG. 10 is an explanatory diagram showing a multiplexed data decoding method according to a sixth embodiment of the present invention.
FIG. 11 is an explanatory diagram of a conventional multiplex data transmission method.
FIG. 12 is an explanatory diagram of a conventional multiplex data transmission method.
FIG. 13 is an explanatory diagram of a conventional multiplex data transmission method.
FIG. 14 is a block diagram of a multiplexed data decoding device that decodes data multiplexed by a conventional data multiplexing method.
FIG. 15 is an explanatory diagram showing the operation of a CPU in a conventional multiplexed data decoding device.
[Explanation of symbols]
1 First data multiplexing unit
2 Second data multiplexing unit
3. Third data multiplexing unit
11 Clock generation circuit
12 CPU
13 Buffer
14 Image encoder
15 Audio Encoder
16 Data encoder
21 Image encoder
22 Audio Encoder
23 Data Encoder

Claims (6)

When generating a multiplexed packet by multiplexing a data packet including one or more types of digital data and a table packet including a table indicating the content of the packet and the packet number, the content of the table packet is changed. Before sending a data packet corresponding to a table packet, an instruction signal indicating that the table packet is changed and a changed table packet are multiplexed on the multiplex packet. 2. A table before receiving the instruction signal when receiving an instruction signal indicating that a table packet is to be changed when receiving the multiplexed packet according to claim 1 and separating a data packet including one or more types of digital data. A multiplexed data decoding method characterized by selecting and receiving both a data packet indicated by a packet and a data packet indicated by a table packet after receiving an instruction signal for a predetermined time. When multiplexing a packet including one or more types of digital data and a packet including a reference time signal of a decoding device, a packet of the reference time signal multiplexed before the packet including the digital data has a continuous reference time signal. A data multiplexing method characterized by adding a reference time signal discontinuity flag indicating that the flag is not present, and multiplexing the flag. When multiplexing a packet including one or more types of digital data and a packet including the reference time signal of the decoding device, if the contents of the digital data are discontinuous, the reference time signal transmitted immediately after the discontinuity point A data multiplexing method, wherein a packet is provided with a reference time signal discontinuity flag indicating that the reference time signal is not continuous, and the flag is also multiplexed. When multiplexing a plurality of packets including audio data or image data, if the sampling frequency of the audio data or image data changes, a packet describing the changed sampling frequency is sampled at the changed sampling frequency. A data multiplexing method characterized by multiplexing before a packet to be included in time. In the case of transmitting a plurality of packets including audio data, if the emphasis characteristic of the audio data changes, a flag indicating that the emphasis characteristic has changed, or a packet describing emphasis characteristic data describing the emphasis characteristic itself, A data multiplexing method, wherein the packet is sent temporally before a packet containing audio data having the changed emphasis characteristic.

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