JPH11127413A - Digital signal processing method and digital signal processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the normal operation of view reservation and an accounting system by not performing the correction of reference time through the present time information which is included in a digital broadcasting signal about a reproduction signal from a storage medium. SOLUTION: Data that includes present time information is sent by a packet which has a prescribed packet (P) ID, present time information extracting means 1 extracts a packet that has a prescribed PID from a TS signal and analyzes it. In this way, the extraction of the present time information is performed and the reference time of a clock which is included in a digital broadcasting receiver and a recording and reproducing device or the like is corrected by inputting the acquired present time information to a reference time correcting means 3 when receiving broadcasting. On the other hand, an input from the present time information extraction 1 is ignored, the function of the means 3 is stopped and the correction of the reference time is not performed by inputting a flag (H level) which shows that it is a reproduction mode to a reproduction mode flag input terminal 7 of the means 3 when reproducing a recorded medium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital signal processing method and a digital signal processing apparatus in a digital signal recording / reproducing apparatus or the like incorporating a digital broadcast receiver.
In particular, it relates to processing of current time information recorded on a recording medium.

[0002]

2. Description of the Related Art Conventionally, various data signals are multiplexed and transmitted together with ordinary video signals and audio signals by digital broadcasting. First, an example of multiplexing of transmission signals in digital broadcasting will be described with reference to FIG. Assuming that a digital broadcast signal is transmitted as an MPEG transport stream, first, a video signal and an audio signal of a certain program (for example, program 1) are
PES (Pack)
etized Elementary Stream) packet, and constitutes a variable-length packet.
Time division multiplexing is performed together with the ES packet.

[0003] A PES packet is a PE containing various information.
It consists of an S header and a PES payload of the data part.

[0004] Next, in order to multiplex the signal obtained in this way with information of another program or information of encryption, and send it out,
Put on TS (Transport Stream) packet. The TS packet is a fixed-length packet of 188 bytes and includes a 4-byte fixed-length TS header, a variable-length adaptation field following the TS header, and a payload.

[0005] FIG. 3 shows the configuration of the above-mentioned PES packet and TS packet. According to the figure, a PES packet is divided and inserted into a payload portion of a TS packet and transmitted. The PID (Packet) is included in the header of the TS packet.
ID) is inserted, and the PES packet includes a plurality of TSs having the same PID number.
It is divided into packet payloads and transmitted. The program is distinguished by the PID number of the TS packet. Here, when the program is to be subjected to conditional access, the scramble key Ks is set as shown in FIG. 2 before the signal of the program is loaded on the payload of the TS packet.
To scramble. The scramble key Ks and the attribute information of the program are stored in an ECM (Entitlement control Message).
e) After being encrypted with the work key Kw, TS
It is packetized and multiplexed. PES packets are similarly formed for other programs (here, program 2... Program k), and after being converted into TS packets, time-division multiplexed with information on other programs. The work key Kw is transmitted as an EMM (Entitlement Management Message) together with other contract information as a TS packet having a predetermined PID. FIG. 4 shows the specific contents of the ECM and the EMM and the number of bits constituting them. Other packets that are multiplexed as TS packets having a predetermined PID include a packet for transmitting information including a reference time (eg, “TDT” (Time and Date Table) in European digital broadcasting), EP
There are program list information for G (Electric Program Guide) and information uniquely set by a broadcaster.

Next, reception and recording of the digital broadcast will be described. FIG. 5 is a block diagram showing a digital recording / reproducing apparatus with a built-in digital satellite broadcast receiver. In the figure, a digital broadcast signal coming from an antenna 201 is subjected to frequency conversion, demodulation,
The signal is subjected to processing such as error correction, and becomes a baseband digital signal, which is supplied to the switch 203. At this time,
The movable section of the switch 203 is on the a side. Switch 20
Although a plurality of programs are time-division multiplexed in the output signal from No. 3, a signal related to a desired program is extracted from the output signal by the demultiplexer 204.

[0007] As described above, a video signal, an audio signal, and a data signal constituting one program are encoded using the video / audio encoding standard of MPEG2 and the standard such as JPEG, and are ES (Elementary Stream). These signals are then converted to PES based on the MPEG2 system standard, and then multiplexed into TS signals, modulated and broadcast. According to the MPEG2 system standard, these multiplexed signals are separated by a receiver,
Information necessary for decryption and information such as program names are PAT
(Program Association Table) signal and PMT (Progr
am Map Table) and multiplexed with the TS signal for transmission.

FIG. 6 is a block diagram showing the function of the demultiplexer 204. First, a PAT (Prog) in which the PID is fixed to a predetermined value from among the input TS signals.
ram Association Table) signal from this predetermined PID
(For example, “0”) is extracted and stored in a predetermined area (here, area 1) in the memory 107. The PAT signal contains a PMT for each program number (16 bits).
(Program Map Table) contains the PID list. By analyzing the contents, the PM
In order to receive T, it is possible to know which PID packet should be extracted. The PAT signal extraction and analysis described above is performed by the PAT extraction / analysis means 103.

[0009] The PMT of a desired program obtained by extracting the PAT signal includes videos constituting the program,
A PID list of a packet in which a stream such as audio and data is transmitted is described. PMT is P
It is extracted from the TS signal by the MT extraction / analysis means 104 and stored in a predetermined area (here, area 2) in the memory 107. Also, by analyzing the PAT,
Data such as video and audio of a desired program can be extracted.

[0010] Information (viewing enablement information) necessary for conditional access such as an EMM is obtained by extracting a packet having a predetermined PID, and is stored in a predetermined area (here, area 4) in the memory 107. You.

The extraction and decoding of the EMM are performed by the EMM extraction / decoding means 101. The extraction of the EMM is performed by extracting a packet having a predetermined PID in the TS signal, and the encryption of the EMM is decrypted by the master key Km stored in the receiving device. The EMM is transmitted at intervals of several days to one month, for example, and is not always transmitted. However, the latest work key Kw stored in the area 4 of the memory 107 is used.

If the extracted data such as video and audio is scrambled, it is released. For that purpose, it is necessary to obtain a scramble key Ks. Since the scramble key Ks is transmitted by the ECM, the ECM extraction / decryption means 102 based on the PID of the ECM of the program described in the PMT.
To extract the ECM from the TS signal.

[0013] Since the ECM is encrypted with the scramble key Ks, the ECM extraction / decryption means 102 uses the work key Kw described in the EMM to decrypt and decrypt the ECM. Then, it is stored in a predetermined area (here, area 3) in the memory 107.

[0014] Of the signals related to the desired program that have been extracted and descrambled by the packet extraction / descrambler 105 of the demultiplexer 204, the video signal and the audio signal are compressed by, for example, the MPEG2 compression method. . This compression is used for video / audio
The signal is decoded by the o-decoder 206 and further converted into an analog signal by a D / A converter (not shown). Then, the NTSC / PAL encoder 207 outputs the NT
The signal is output as a standard TV signal such as an SC signal or a PAL signal.

When recording the received digital broadcast signal on a recording medium, a signal to be recorded is extracted by a packet extracting / descrambling means 105 of the demultiplexer 204, and PAT information and PMT to be recorded simultaneously are extracted.
The information is rewritten by the PAT / PMT rewriting means 106 of the demultiplexer 204 to contents limited to those relating to signals to be recorded. The multiplexing means 108 multiplexes the video signal, the audio signal, and the like with the rewritten PAT and PMT, and
05 recorded.

When a signal recorded on a recording medium is reproduced, the movable section of the switch 203 is set to the b side, and the digital signal reproduced by the demultiplexer 204 includes a signal such as a video signal and an audio signal relating to a desired program. The information necessary for the restoration is extracted and processed in the same way as when receiving the broadcast.

[0017] Although not shown, a communication device such as a modem is provided as a function of the digital broadcast signal receiving unit, and a fee is paid only when a viewer wants to watch a program using the device. Pay Per View
View) Billing is performed by sending viewing information such as how much the program has been viewed to the broadcasting station via a telephone line or the like as appropriate.

[0018]

In the recording / reproducing apparatus integrated with the digital broadcast receiver as described above, the present time information at the time of reception among the received digital broadcast signals is also recorded on a recording medium. There has been a problem that the current time displayed when playing is different from the actual current time. Further, when calibrating the reference time of a clock built in a digital broadcast receiver or a recording / reproducing device based on current time information multiplexed in a digital broadcast signal,
Since the reference time is calibrated based on the current time information recorded at the time of reproduction, there is a problem that the time is set to an incorrect time and a viewing reservation, a billing system, and the like do not operate normally.

[0019]

SUMMARY OF THE INVENTION In view of the above problems,
The present invention receives a digital signal in which a plurality of programs and information indicating the current time are transmitted integrally, extracts information indicating the current time from the digital signal, and extracts the extracted current time. In a digital signal processing device for calibrating a reference time of a built-in clock by information representing time,
When the digital signal is a recorded signal, a digital signal processing method is provided which detects information indicating the digital signal and does not calibrate the reference time of the timepiece.

[0020] Further, a receiving means for receiving a digital signal in which a plurality of programs and information representing the current time are transmitted together, and a current time extracting the information representing the current time from the digital signal Information extracting means, when the digital signal is provided for recording, inserting information indicating that recording is completed into the information indicating the current time, and rewriting means for rewriting the information indicating the current time; And a reference time calibration means for calibrating a reference time of the clock indicating the current time by the information indicating the current time, wherein the recorded digital signal is reproduced. A digital signal processing device, wherein the reference time calibration means is stopped by the information indicating the recorded state.

[0021] Further, a receiving means for receiving a digital signal in which a plurality of programs and information indicating the current time are transmitted together, and a current time for extracting the information indicating the current time from the digital signal Information extracting means, recording / reproducing means for recording / reproducing the digital signal, a clock indicating a current time, and reference time calibrating means for calibrating a reference time of the clock indicating the current time by the information indicating the current time. A digital signal processing device comprising: when the digital signal is reproduced, the reference time calibration means is stopped by a signal output from the recording / reproducing means and indicating a reproduction mode. A digital signal processing device is provided.

[0022] Still further, the apparatus further comprises transmission processing means for performing signal processing for transmitting the digital signal received by the receiving means and the digital signal reproduced by the recording / reproducing means to an external device, wherein the digital signal is When the data is reproduced by the recording / reproducing means, information indicating the reproduction is added to the digital signal by the transmission processing means.

[0023]

FIG. 1 is a block diagram showing one embodiment of an information selection method and an information selection device according to the present invention.
The same components as those in the conventional example are denoted by the same reference numerals, and description thereof will be omitted. The digital broadcast signal coming from the antenna 201 is subjected to processing such as frequency conversion, demodulation, and error correction in the front end 202, becomes a baseband digital signal, and is supplied to the switch 203. At this time, the movable section of the switch 203 is set to the a side. A plurality of programs are time-division multiplexed on the output signal from the switch 203, and a signal related to a desired program is extracted from the output signal by the demultiplexer 204.

[0024] Of the signals related to the desired program extracted and descrambled by the demultiplexer 204,
The video signal and the audio signal are compressed by, for example, the MPEG2 compression method. This compression is called video / a
The signal is decoded by the audio decoder 206 and further converted into an analog signal by a D / A converter (not shown). Then, the signal is output as a standard TV signal such as an NTSC signal or a PAL signal by the NTSC / PAL encoder 207.

Since the data including the current time information is sent in a packet having a predetermined PID, the current time information extracting means 1
Thus, a packet having a predetermined PID is extracted from the TS signal and analyzed. As a result, the current time information is extracted. At the time of receiving the broadcast, the obtained current time information is input to the reference time calibration means 3 so that the reference time of the clock incorporated in the digital broadcast receiver or the recording / reproducing apparatus is obtained. The time is calibrated.

On the other hand, when reproducing the recorded medium, a flag (for example, H level) indicating the reproduction mode is input to the reproduction mode flag input terminal 7 of the reference time calibration means 3 to extract the current time information. The input from the means 1 is ignored, and the function of the reference time calibration means 3 is stopped so that the calibration of the reference time is not performed.

Note that this digital signal recording / reproducing apparatus has a digital output 6 so that when a reproduced signal is transmitted to an external digital broadcast receiving apparatus for viewing, a program based on the digital broadcast signal is recorded on a recording medium. , And the information indicating that the program is recorded. For this purpose, a special bit may be allocated and indicated on the recording and transmission format, and the function of the reference time calibration means 3 may be stopped by detecting this bit. For example, in the current time information, the program is recorded by rewriting by the rewriting means 2 to a value not used when representing the actual time such as "32 days" or "25:00". You may do it. In this case, when these values are detected, the signal is regarded as a reproduction signal from the recording medium, and the reference time calibration means 3
Function is stopped so that the reference time is not calibrated.

As described above, the digital broadcast signal of the digital signal recording / reproducing apparatus of the present invention is output from the digital signal output terminal 6 via the transmission processing means 5 and the signal is recorded even when transmitted to another apparatus. You can tell if it was done.

Further, even when a reproduction signal reproduced by another recording / reproducing device is input from the external digital input terminal 4 as a receiving side of the device, a predetermined flag is detected from the signal, whereby a reference signal is detected. Incorrect calibration of the time can be reliably prevented.

Another method is to transmit a signal from a reproducing apparatus to another apparatus during reproduction without adding a flag indicating that the digital broadcast signal is recorded at the time of recording. The transmission processing means 5 sets a predetermined flag indicating that this signal is recorded, or a time information flag indicating that the current time information is present in a predetermined packet in a digital broadcast format. By the presence or absence of the current time information, when receiving a digital broadcast signal, assuming that there is a time information flag, insert the current time into a predetermined number of bits that follow, thereby calibrating the reference time, The time information flag is rewritten to indicate that there is no time information at the time of recording the digital broadcast signal, and the subsequent current time information is deleted. Thus, the calibration of the reference time is not performed.

[0031]

According to the digital signal processing method and the digital signal processing apparatus of the present invention, the calibration of the reference time based on the current time information included in the digital broadcast signal is not performed on the reproduced signal from the recording medium. Therefore, there is an effect that the reference time is not erroneously calibrated, and the viewing reservation and the billing system can be normally operated.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a digital signal processing method and a digital signal processing device according to the present invention.

FIG. 2 is a diagram illustrating multiplexing of a transmission signal in digital broadcasting.

FIG. 3 is a diagram showing a configuration of a PES packet and a TS packet.

FIG. 4 is a diagram showing the contents of ECM and EMM and the number of constituent bits.

FIG. 5 is a block diagram illustrating an example of a conventional information selection device.

FIG. 6 is a diagram illustrating a demultiplexer used in a conventional digital signal processing method and a digital signal processing device.

[Explanation of symbols]

 1 current time information extraction means 2 rewriting means 3 reference time calibration means 4 external digital input terminal 5 transmission processing means 6 digital output terminal 7 playback mode flag input terminal 201 antenna 202 front end 203 switch 204 demultiplexer 205 recording / playback unit 206 video / Audio decoder 207 NTSC / PAL encoder

Claims (4)

[Claims] 1. A digital signal in which a plurality of programs and information indicating a current time are transmitted together, and information indicating the current time is extracted from the digital signal.
In a digital signal processing device for calibrating a built-in reference time of a built-in clock based on extracted information indicating a current time, when the digital signal is a recorded one, information indicating the digital signal is detected, and the digital signal is detected. A digital signal processing method characterized by not calibrating a reference time. 2. A receiving means for receiving a digital signal in which a plurality of programs and information representing the current time are transmitted together, and a current time extracting the information representing the current time from the digital signal. Information extracting means, when the digital signal is used for recording, inserting information indicating that recording is completed into the information indicating the current time, and rewriting means for rewriting the information indicating the current time; And a reference time calibration means for calibrating a reference time of the clock indicating the current time according to the information indicating the current time, wherein the recorded digital signal is reproduced. Wherein the reference time calibration means is stopped by the information indicating the recorded state. 3. A receiving means for receiving a digital signal in which a plurality of programs and information representing the current time are transmitted together, and a current time for extracting the information representing the current time from the digital signal. Information extracting means, recording / reproducing means for recording / reproducing the digital signal, a clock indicating a current time, and reference time calibrating means for calibrating a reference time of the clock indicating the current time with the information indicating the current time. A digital signal processing device comprising: when the digital signal is reproduced, the reference time calibration means is stopped by a signal output from the recording / reproduction means and indicating a replay mode. Digital signal processing device. 4. A transmission processing means for performing signal processing for transmitting a digital signal received by said receiving means and a digital signal reproduced by said recording / reproducing means to an external device, wherein said digital signal is said recording signal. 4. The digital signal processing apparatus according to claim 3, wherein, when the digital signal is reproduced by the reproducing means, information indicating the reproduction is added to the digital signal by the transmission processing means.