JP2000341597A - Digital broadcasting receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a digital broadcasting receiver, whose receiver can be controlled by utilizing important information included in the first part of an input signal from a DSM(digital storage media), without discarding a needed packet when reproducing a digital stream from the DSM. SOLUTION: A demultiplexer inserts a plurality of null packets into the head of a Partial TS(partial transport stream) and outputs them as shown in the diagram (C), when outputting the Partial TS to a DSM. The transport stream synchronization of a receiver is established by the null packets, transport packets to be discarded by the synchronization establishment become the null packets that are originally unnecessary, and the pay load of the effective packets to be inputted after the synchronization establishment all become usable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital broadcast receiver for receiving digital broadcasts, and more particularly, to input and output of data to and from a digital storage medium such as a digital VTR capable of storing a digital stream based on a digital broadcast signal. The present invention relates to a digital broadcast receiver having an interface.

[0002]

2. Description of the Related Art In digital broadcasting currently performed in CS broadcasting, video and audio digital data of a plurality of programs compressed by the MPEG2 system are transported together with program information, limited reception information and the like in a transport stream (hereinafter abbreviated as TS). Multiplexed) and transmitted. If the compressed video and audio digital data is recorded using a digital storage medium (hereinafter abbreviated as DSM) that can directly record a digital stream such as a digital VTR, the decoded signal can be recorded using an analog VTR. Also, it is possible to efficiently record without deteriorating the image quality. In addition, since additional information such as program information, which is a feature of digital broadcasting, can be recorded at the same time, the information can be used during reproduction.

[0003] The data rate of a digital stream that can be recorded on a DSM is often smaller than the rate of a digital broadcast TS. Therefore, a digital broadcast receiver having a digital interface that outputs a stream to DSM has a function of selecting and outputting information related to a specific program in order to reduce the transmission rate of the output stream. There is. FIG. 2 shows a configuration example of such a receiver.

FIG. 2 is a block diagram showing a configuration example of a digital broadcast receiver. In FIG. 2, NIM (network interface module) (reception demodulation unit) 1
Has a function of signal processing in a transmission system such as a tuner, digital demodulation, and error correction, and its output is a TS, which is supplied to the descrambler 2. Descrambler 2
A specific transport packet is sent to the host controller 5
And the output signal TS-a is supplied to the stream selector 6 and the stream selector 7. The stream selector 6 receives two signals of a broadcast signal supplied from the descrambler 2 and a digital input signal (TS-c) from the DSM, selects one of them, and supplies it to the demultiplexer 3.

FIG. 4 is a diagram for explaining a transport stream (TS). The TS (TS-a) of the broadcast signal output from the descrambler 2 includes compressed video / audio signals of a plurality of programs and additional information such as program names, as shown in FIG. Are multiplexed in units of transport packets. A packet (V) including a video and audio elementary stream (ES) of a certain program n
n, An), PAT (Program Associaion Table),
PSI (Program S) such as PMT (Program Map Table)
pecific Information: Program identification information, SI (Service
Information: program arrangement information) is time-division multiplexed.

[0006] The demultiplexer 3 extracts PAT, PMT and the like included in the TS, and based on the extracted information,
According to an instruction from the host controller 5, a transport packet of a video and audio stream related to a certain program is specified and supplied to the MPEG decoder 4. MP
The EG decoder 4 decodes the video and audio streams and outputs them as video and audio signals.
The demultiplexer 3 selects information related to a specific program and supplies it to the stream selector 7. The stream selector 7 selects the Partia selected by the demultiplexer 3
Input two signals of lTS (TS-b) and all TS (TS-a) before selection, and select either one and DSM as digital output
Output to

FIG. 3 is a block diagram showing a configuration example of the demultiplexer in FIG. The transport packet has a 13-bit PID (Packet Identif
ication: packet identifier), whereby the attribute of the packet can be specified. Further, PSI, SI, and the like have a data structure called a section, and are stored in a payload portion of a transport packet.

In FIG. 3, a TS synchronization signal detecting circuit 11
Receives a TS signal from the stream selector 6 in FIG. 2, detects a synchronization byte indicating the head of a transport packet from a bit stream, and
2. The synchronization byte serves as a starting point for syntax analysis of the subsequent transport packet. Since the bit pattern indicating the synchronization byte can appear in other parts of the transport packet, in order to avoid false synchronization, usually, by detecting the synchronization byte multiple times,
The synchronization of the TS packet is determined.

[0009] The PID filter 12 detects a PID on a bit stream that can be detected by a relative position from the synchronization byte.
A value is extracted, a packet containing necessary information is selected using the value, and the packet is stored in the memory 14. PID filter 12
Among the packets selected by (1), the packet including the data of the section structure is further analyzed by the section filter 13, and the sections of the program identification information such as PAT and the program arrangement information are extracted therefrom, and the host controller 5 shown in FIG. Are stored in the memory 14 in a form that can be referred to.

The host controller 5 shown in FIG. 2 reads out the information via the memory controller 15 and performs appropriate processing such as physical channel selection, program selection, and presentation of service information. Packets containing video and audio ESs (elementary streams) are identified by the preceding section information,
Only the transport packet (or PES or ES included in the transport packet) is output to the MPEG decoder. With this operation, the user can select one desired program from a TS in which a plurality of programs are multiplexed.

[0011] The selected transport packet containing necessary information is also output to the DSM. The output TS (TS-b) is different from the TS for the MPEG decoder in that not only one program is selected,
The point is that auxiliary information such as PSI is output at the same time. or,
When a specific program is selected from the original TS and output to the DSM, PSI or the like is changed and output so that the TS does not violate the MPEG regulations. Further, the SI uses a specific packet SIT (Selection Inform
ation Table: selection information table).

Therefore, the output of TS to DSM (TS-
FIG. 4B shows a partial TS (partial transport stream: partial TS) shown in FIG. This example shows a case where program 1 is selected from a TS in which programs 1 and 2 (V1 to V2, A1 to A2) are multiplexed. In this case, the video and audio packets (V1,
A1) is selected and output, and accordingly, PAT, PMT
No. 1 changes and deletes the information about the program which was not selected, and outputs it. The SI extracts information on the selected program into SIT packets and outputs the SIT packets. In addition, where the SI information becomes discontinuous, DIT (Disc
ontinuity Information Table)
Insert

Therefore, the demultiplexer 3 uses the program specifying information obtained from the TS, together with the program selection information from the user, and instructs the video or video related to one or more programs by an instruction from the host controller 5. Selectively output the transport packets of the audio stream.
At the same time, it also outputs a packet containing necessary PSI and SI information. These packets need to be changed according to the selected TS, and the correction is performed by software processing by the host controller 5 or by hardware processing by the demultiplexer 3.

[0014]

SUMMARY OF THE INVENTION Pa accumulated in the DSM
A problem when rtialTS is re-input to the digital broadcast receiver and demultiplexed by the demultiplexer 3 is that when important information is included at the beginning of the TS,
It can be destroyed. As described above, since the bit pattern of the synchronization byte of the transport packet can appear in other parts of the TS, synchronization cannot be established unless the synchronization byte is detected a plurality of times.

FIG. 5 shows the TS synchronization signal detecting circuit 1 shown in FIG.
3 is a flowchart showing a procedure of TS synchronization detection in No. 1; In FIG. 5, first, the number N of times of synchronous byte detection is set to 0.
(S1: step 1). Next, the bit stream input to the demultiplexer is scanned to detect a synchronization byte (S2: step 2). Next, when a synchronization byte is detected, the number of times of detection is counted up (step 3). Next, it is determined whether or not the number N of synchronization bytes detected before that exceeds the set number N1 of determinations of synchronization establishment, and determination of synchronization determination is performed (step 4).

If it does not exceed (NO) (if N ≦ N1), it is determined whether the data one transport packet ahead (188 bytes long) is a synchronization byte (step 5).
If it is a synchronous byte (YES), the flow returns to step 3 to count up the number of detections. Not a sync byte
In the case of (NO), the process returns to the first step 1, the number of detections N is initialized, and scanning is started from the synchronization byte on the bit stream. If N exceeds N1 (YES) (N>
N1), it is determined that synchronization has been established, and P
The operation shifts to the ID analysis operation (step 6) and ends. N1 is usually set to 3 or more to avoid detection of a pseudo sync byte.

When the synchronization detection procedure as shown in FIG. 5 is used, there is a problem that a plurality of packets (N1) are discarded until synchronization is established. Meanwhile, Partia
In lTS, table information called DIT specific to PartialTS is inserted at a change point where SI information becomes discontinuous. Therefore, when outputting PartialTS to DSM,
In many cases, a transport packet including a DIT is inserted at the head and output. However, when the input transport stream from the DSM is demultiplexed by the digital broadcast receiver, if the plurality of leading transport packets are discarded due to TS synchronization detection, the DIT information cannot be referred to. There was also a problem.

The DIT can be used for the purpose of prompting the switching of the SI processing in the digital broadcast receiver due to the characteristic that the DIT is inserted at a discontinuous point of the SI information. Further, since the table is only allowed in the Partial TS, the presence of the DIT can be used to determine whether the TS is a Partial TS or all TSs. Therefore, at this time, D
If the IT information cannot be referred to, there is a possibility that processing of PSI and SI information is delayed, and problems such as delay of presentation to a user such as an EPG and presentation of a decoded image occur.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and when reproducing a digital stream from a DSM (Digital Storage Medium), necessary packets are not discarded, and the payload is effective. It is possible to provide a digital broadcast receiver capable of controlling the operation of the receiver by using the important information included in the first part of the input signal from the DSM. Aim.

[0020]

To achieve the above object, a receiving and demodulating section for receiving and demodulating a digital broadcast signal is provided.
Digital signal output means for selecting and outputting all or a part of the transport stream demodulated by the reception demodulation section, digital signal input means for inputting an external transport stream, and the reception demodulation section or the digital A digital broadcast receiver comprising: a demultiplexer that analyzes a transport stream input from a signal input unit and selects a desired packet from the transport stream; and a decoder that decodes an output of the demultiplexer. The demultiplexer provides a digital broadcast receiver characterized in that, when a partial transport stream is output to a digital storage medium, a plurality of null packets are inserted at the head and output.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the basic principle of the present invention will be described. The present invention solves this problem by inserting a plurality of null packets at the beginning when outputting a PartialTS to the DSM. The null packet is a transport packet having a PID of 1FFF (hexadecimal number), and is used for padding a packet in the MPEG system, and its payload is discarded by the demultiplexer 3. However, since the header (synchronization byte) of the transport packet exists, it can be used for synchronization establishment.

Therefore, in the digital broadcast receiver of the present invention,
When outputting the PartialTS from the receiver to the DSM,
A plurality of null packets are output, followed by output of valid packets (PSI, DIT, packets including the selected ES, etc.). FIG. 1 is a diagram for explaining a transport stream according to the present invention.
In FIG. 1, FIG. 1A shows a TS before demultiplesk. FIG. 1B shows a Partial TS output from a conventional digital broadcast receiver. FIG. 1C shows a PartialTS output from the digital broadcast receiver of the present invention.
(NULL) packet is inserted at the beginning.

Normally, in the DSM, the input stream is stored as it is, and therefore, at the time of reproduction, the receiver receives the stream output by itself as it is. At this time, since a null packet exists at the head of the received stream, the transport stream synchronization of the receiver is established by this null packet, and the transport packet discarded before the synchronization is established becomes a null packet which is not originally required. That is, all payloads of valid packets input after synchronization is established can be used.

As described above, the digital broadcast receiver of the present invention can analyze data from the payload of the first valid transport packet when reproducing the TS once stored in the DSM, Since all input information from DSM can be used, EP
There is an effect that switching of the G processing operation can be performed quickly.
In the present invention, the input and output digital interfaces may be physically common. Further, it is needless to say that a device for converting the TS into another signal form and outputting the converted signal in the digital broadcast receiver and converting the signal input in the form into the TS again may be provided.

[0025]

As described above in detail, the digital broadcast receiver according to the present invention does not discard necessary packets when reproducing a digital stream from a DSM (Digital Storage Media), and does not discard its payload. Can be started from the first packet in which the DSM is valid, and it is possible to control the operation of the receiver by using important information included in the first part of the input signal from the DSM. is there.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a transport stream in the present invention.

FIG. 2 is a block diagram illustrating a configuration example of a digital broadcast receiver.

FIG. 3 is a block diagram illustrating a configuration example of a demultiplexer in FIG. 2;

FIG. 4 is a diagram for explaining a transport stream.

FIG. 5 is a flowchart illustrating a procedure of TS synchronization detection.

[Explanation of symbols]

 Reference Signs List 1 NIM (reception demodulation unit) 2 Descrambler 3 Demultiplexer 4 MPEG decoder 5 Host controller 6, 7 Stream selector

Claims (1)

[Claims] 1. A receiving and demodulating section for receiving and demodulating a digital broadcast signal, digital signal output means for selecting and outputting all or a part of a transport stream demodulated by the receiving and demodulating section, and an external transport Digital signal input means for inputting a stream, a demultiplexer for analyzing a transport stream input from the reception demodulation unit or the digital signal input means, and selecting a desired packet from the same, and an output of the demultiplexer And a decoder for decoding a partial transport stream, wherein when outputting a partial transport stream to a digital storage medium, the demultiplexer inserts and outputs a plurality of null packets at the beginning of the partial transport stream. A digital broadcast receiver, characterized in that: