JP2000032426A - Receiver for transport stream - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a stiff TS demultiplex processing, even with respect to a transmission fault or a reception fault. SOLUTION: Even when a version number is revised, the receiver acquires a desired packet that includes an ID to specify whether or not the packet is to be acquired and a version number that is revised from an MPEG2-TS whenever time contents of the packet are revised. In this case, a pattern match filter 24 extracts the packet, when the pattern match filter 24 detects matching of a pattern of the ID from the TS. A pattern unmatching filter 25 extracts the packet, when the filter 25 detects that a version number included in the packet extracted by the filter 24 differs from the version number monitored at present. A CPU8 acquires the packet, when the filter 25 extracts the desired packet and uses the version number monitored next to be a newly detected version number.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
2 (Moving Picture Experts Group Phase 2)-TS
The present invention relates to a receiving device that acquires a desired packet from a multiplexed transport stream, such as a (Transport Stream), and particularly to a transport stream receiving device that is adapted to enhance adaptability when a failure occurs.

[0002]

2. Description of the Related Art In digital data broadcasting, in the case of digital CS broadcasting, for example, in digital CS broadcasting, video and audio are digitized in the form of MPEG2-TS and sent to the receiving side. At this time, TS contains
ProgramSpecific Information:
PSI) and service information (Service Information: S)
Program-related information called I) is also sent at the same time. All of this information is packetized into 188-byte fixed-length data called TS packets and multiplexed. The digital broadcast receiver first obtains the PSI, extracts the packet ID (PID) of the video or audio stream, and always captures the information while receiving the information.
Updates are needed. PSI and SI are MPE
It conforms to the section format specified by the G2 system. In this section, a field (5 bits) called a version number is provided for managing data update. Although the operation method of the version number depends on the broadcasting service, usually, the version number is often incremented by updating information. Therefore, the digital broadcast receiver has a certain PSI
Is received, information having a value obtained by incrementing the version number by one is waited.

In order to extract only a desired TS packet from the multiplexed MPEG2-TS, the receiving apparatus is provided with a DEMUX (demultiplexer). D
The EMUX specifies a PID and a bit pattern of several bytes following the PID, compares the PID with an input stream by an internal determination circuit, and if the pattern matches the specified pattern, writes the packet to a predetermined memory, and It has a function of notifying the arrival to the host CPU and the like.

[0004]

The conventional system has no problem when transmission and reception are normally performed.
A problem occurs when a transmission failure or a reception failure occurs and the information to be received is not a grammatical or semantic error but is transmitted in a pattern different from the bit pattern that should be transmitted. In this case, since the receiving side cannot detect a pattern that matches the specified pattern, the receiving side may wait for a long time, or in some cases, several days. In particular, the discontinuity of the version numbers becomes a problem.

[0005] This problem will be described in more detail with reference to FIG. It is assumed that a TS packet with version number = 1 is currently acquired and that a TS packet with version number = 2 is ready to be acquired. In the case of program information or the like, the version number is updated, for example, once a day. However, since the receiving side does not know when to start receiving, the same type of TS packet of this type is repeatedly retransmitted at regular intervals. DEMUX of receiver
Performs pattern matching with a specific matching field including a packet ID and a version number, and in this example, waits for a packet with a packet ID = 80 and a version number = 2, and ignores a packet with a version number = 1. If a communication failure occurs here,
For example, switching of the MUX (multiplexer) on the transmission side occurs, and the version number becomes, for example, 4, and the continuity of the version numbers is lost. In this case, since the receiving side is waiting for version number = 2, it is not possible to acquire the updated packet, and the receiving side is in a long waiting state.

In order to avoid such a problem, a method of ignoring the version number and capturing data is conceivable. However, since information such as PSI is frequently retransmitted,
Each time, the host CPU must determine whether the data is update data, and the efficiency is low. As another workaround, the host CPU periodically checks the data acquisition status, and if it is determined that there is an abnormality, it is conceivable to perform PSI reacquisition processing. However, it is difficult to accurately determine the abnormality, This is not a fundamental solution.

[0007] The present invention has been made in view of such a problem, and a TS that is robust against a transmission failure or a reception failure.
An object of the present invention is to provide a transport stream receiving device capable of realizing demux processing.

[0008]

According to the present invention, there is provided a transport stream receiving apparatus comprising, from a multiplexed transport stream, first information for identifying a packet to be acquired and the content of the packet. In a transport stream receiving apparatus that acquires a desired packet including second information that is changed each time it is changed, every time the second information is changed, A first filter for detecting the first information to extract the desired packet and a second information currently monitored for the second information included in the packet extracted by the first filter are as follows. A second filter for extracting a packet extracted by the first filter when a difference is detected; and a desired packet extracted by the second filter. Further comprising subsequently a control unit for updating the second information to the second information newly detected to monitor as well as acquiring the packet when it is characterized.

Here, the desired packet is data that is repeatedly transmitted with the same contents while the second information is changed. The first filter may extract the packet when a match between a specific matching field of the packet to be acquired and a first pattern is detected, for example. The second filter may extract a packet when a mismatch between a specific matching field of the packet to be acquired and a second pattern is detected.

According to the present invention, the second information to be updated each time the content of the packet is updated is monitored for coincidence with the second information of the updated packet to be acquired next. In other words, it is monitored that the second information does not match the second information of the current packet. Therefore, even if the second information is not updated in a predetermined order due to the occurrence of a failure, the current second information is not updated. , The update of the packet can be detected.

If the control means obtains a desired packet periodically regardless of the update of the second information, even if the same second information happens to be received at the time of the failure, To a certain extent, long waits can be avoided.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a CS digital broadcast receiving apparatus according to one embodiment of the present invention. The CS reception signal received via the antenna 1 is demodulated by the tuner 2 and error-corrected by the error correction unit 3. The error-corrected data is descrambled by the descrambler 4 and
It is supplied to a demultiplexer (DEMUX) 5. DE
The MUX 5 extracts only necessary information from the multiplexed information. Control information and program-related information are supplied to the CPU 8 via the data buffer 6 and the system bus 7. ,
The data is supplied to the MPEGA / V decoder 9 and decoded. The decoded video data is further encoded by a video encoder 10 into an NTSC video signal and output. The system bus 7 has C
In addition to the PU 8, a switch / remote controller input unit 12 for receiving an infrared signal from the remote controller 11, a RAM / R for storing an operation program of the CPU 8 and providing a work area
An OM 13, a conditional access module 14 for obtaining a key for descrambling, and a modem 15 for transmitting and receiving data to and from a telephone network are connected.

FIG. 2 shows the DEMUX in the above system.
FIG. 5 is a functional block diagram showing a more detailed configuration of FIG. Note that only the flow of control information and program-related information and the like are specifically shown here, and the flow of video data and audio data is omitted. The DEMUX 5 includes a TS packet framer 21, a PID filter, a unit start detector 23, a pattern match filter 24, and a pattern unmatch filter 25.

FIG. 3 shows an example of a typical MPEG2-TS packet and a section constituted by the packet. As shown in FIG. 3A, the TS packet is a fixed-length packet of 188 bytes composed of a 4-byte header and 184 data bytes. The header contains a synchronization byte (8 bits), a payload unit,
Information such as start (1 bit) and PID (13 bits) is included. The TS packet framer 21 inside the DEMUX 5 executes a process of cutting out a TS packet having a fixed length of 188 bytes with reference to the synchronization byte and the like. The PID information indicated in the TS header of the TS packet extracted by the TS packet framer 21 is checked by the PID filter 22, and a packet matching the PID specified by the CPU 8 is extracted. A data byte portion is extracted from the cut-out TS packet, and a plurality of TS
The data byte portions extracted from the packet are combined to form a data block in the section format defined by the MPEG2 system as shown in FIG. In forming a section, as information indicating which TS packet is at the head, 1 indicating whether or not a data packet of the packet includes a section header.
A bit payload_unit_start_indicator is provided. The unit start detection unit 23 monitors this information and detects the first packet.

FIG. 3C is a diagram showing an example of a bit arrangement of the formed section. A section header is provided at the head of the section. The section header is composed of 8 bytes in this example, and includes, for example, the following information. table_id (8 bits) Table identification information section_length (12 bits) Section length table_id_extention Field used to extend table_id version_number Information for determining whether table information is updated section_number Table is composed of a plurality of sections Last_section_number: ID number of the last section when the table is composed of multiple sections

The section header is compared in a pattern matching filter 24 with a matching pattern provided from the CPU 8. Pattern match filter 24
Is also provided with a mask pattern from the CPU 8, and the mask pattern is used to mask bits irrelevant to the pattern matching of the section header before performing the matching process. Here, as the first information for specifying the TS packet to be acquired, for example, table_id
= 23h, table_id_extention = 0456h, and the second pattern changed every time the contents of the packet are changed, the version_number! = 1 (other than 1). , FIG.
All of the first and second information are picked up using a mask pattern as shown in (e), and at the same time, a match with the pattern is detected to detect the update of the contents of the TS packet.

On the other hand, in the present invention, the update of the contents of the TS packet is detected using two filters, a pattern match filter (first filter) 24 and a pattern unmatch filter (second filter) 25. First,
The pattern match filter 24 uses a mask pattern as shown in FIG.
d, pick up only the table_id_extention part and mask other parts. Then, as shown in FIG. 3B, the currently waiting table_id = 23h, table_id_exten
Pattern matching with “tion = 0456h” is performed, and if matched, the packet is extracted.

Next, the pattern unmatch filter 25 uses the mask pattern as shown in FIG. 4 (e) to pick up only the version_number, which is the second information, and mask the other parts. Then, FIG.
Version_number! = 1
As a result of the pattern unmatching process, if a mismatch is detected, the packet is written to the data buffer (queue buffer memory) 6 connected to the DEMUX 5, and when the section is completed, the desired data arrives at the CPU 8. Notify that

According to this apparatus, as shown in FIG. 7 (b), while a TS packet of version_number = 1 is acquired, a failure occurs in a communication line or the like and the version_numbe
Even if r = 4, version_number! = 1
This TS packet can be obtained under the condition (other than 1).

If data arrives with the same version number after a failure occurs, the above-mentioned device cannot detect it. Therefore, regardless of the version number, the CPU 8 may execute a process of periodically taking in data, and after acquiring data, determine whether the data is new data by comparing the content of the data with the previously acquired data. This process is equivalent to periodically resetting the data acquisition process.

FIGS. 5 and 6 are flowcharts for explaining this processing. As shown in FIG. 5, in the normal process, a data arrival notification (Arriva
l Notice) is read, data (version_number = x) is read from the data buffer 6 (S1), and acquisition setting of the next data (version_number! = x) is performed (S1).
2). Then, the acquisition monitoring timer is reset (S
3). On the other hand, in the background of the normal processing process,
The acquisition monitoring process shown in FIG. 6 is executed. That is, until the acquisition reset time is reached (S12), the timer counts up (S11) and the timer waits for a unit time (S13).
Is repeated, and when the acquisition reset time has been reached, the waiting for the current data is released and the acquisition setting of the data ignoring the version is performed (S14). Then, the acquisition monitoring timer is reset (S15). In this way, by interrupting in a fixed time, even if the same version number happens to be received after the occurrence of a failure, the state returns to the normal state after the acquisition monitoring time has elapsed. If the acquisition monitoring time is too short, the load on the CPU 8 increases,
If the length is too long, the waiting time for returning to the normal state when an error occurs increases. However, it is considered that the probability that the same version number as the occurrence of the fault occurs at the same time is extremely small. It is enough.

[0022]

As described above, according to the present invention,
The second information to be updated each time the content of the packet is updated is to monitor the second information of the current packet instead of monitoring the second information of the updated packet to be acquired next. Since the mismatch with the information is monitored, even when the second information is not updated in the predetermined order due to the occurrence of the failure, the packet is updated by the mismatch with the current second information. Can be detected, and the adaptability to the occurrence of a failure can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of a CS receiving apparatus according to one embodiment of the present invention.

FIG. 2 is a functional block diagram of a DEMUX of the device.

FIG. 3 is a diagram showing a structure of an MPEG2-TS packet and a section received by the same device.

FIG. 4 is a diagram for explaining a pattern matching process and a pattern unmatching process in the same device.

FIG. 5 is a flowchart showing a normal processing process obtained by further improving the apparatus.

FIG. 6 is a flowchart showing a data acquisition monitoring process.

FIG. 7 is a diagram showing the operation and effect of the present invention in comparison with a conventional example.

[Explanation of symbols]

5 ... DEMUX, 21 ... TS packet framer, 22 ...
PID filter, 23 ... Unit start detection unit, 24
... Pattern match filter, 25 ... Pattern unmatch filter.

Claims (5)

[Claims] 1. A multiplexed transport stream comprising a first information specifying a packet to be acquired and a second information changed every time the content of the packet is changed. A transport stream receiving apparatus for acquiring the packet of the first time every time the second information is changed, wherein the first
A first filter for detecting the desired packet and extracting the desired packet; and the second information included in the packet extracted by the first filter is different from the second information currently monitored. A second filter for extracting a packet extracted by the first filter when detecting a packet; and a second filter for acquiring and monitoring the packet when a desired packet is extracted by the second filter. Control means for updating the second information to the newly detected second information. 2. The transport stream receiving apparatus according to claim 1, wherein the desired packet is data that is repeatedly transmitted with the same contents while the second information is changed. 3. The method according to claim 2, wherein the first filter extracts a packet when a match between a specific matching field of the packet to be acquired and a first pattern is detected. Item 3. The transport stream receiving device according to item 1 or 2. 4. The method according to claim 1, wherein the second filter extracts a packet when a mismatch between a specific matching field of the packet to be acquired and a second pattern is detected. Item 4. The transport stream receiving device according to any one of Items 1 to 3. 5. The control device according to claim 1, wherein the control unit acquires the desired packet periodically regardless of updating of the second information. Transport stream receiving device.