JP2008288842A - Digital broadcasting receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a digital broadcasting receiver where the time prior to outputting of video images and sound, when power is supplied and when a channel is switched, is shortened. <P>SOLUTION: The digital broadcasting receiver is capable of receiving digital broadcasting and analog broadcasting comprises a digital broadcasting decoding means 100 for decoding encoded digital broadcasting signals; an analog broadcasting demodulation means 200 for demodulating modulated analog broadcasting signals; a switching means 300 for selecting and outputting the digital broadcasting signals from the digital broadcasting decoding means 100 and the analog broadcasting signals from the analog broadcasting demodulation means 200; and a control part 9 for controlling the switching means 300 so as to output the analog broadcasting signals, when power is supplied and when the channel is switched. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a digital broadcast receiver that shortens the time until video / audio is output when power is turned on or when a channel is switched.

  Conventional digital broadcast receivers have a long time until video / audio is output compared to analog broadcast receivers when the power is turned on or when the channels are switched, and thus lack convenience for the user.

  As an improvement measure, there is one that outputs an appropriate signal such as a holding tone to inform the user that the receiver is operating normally until video / audio is output (see Patent Document 1 below). ). In addition, there is a system that enables a user to reserve operation settings such as channel and volume switching operations in advance before video / audio is output (see Patent Document 2 below).

JP 2001-7722 A JP 2006-345336 A

  However, the digital broadcast receivers described in Patent Documents 1 and 2 do not shorten the time until video / audio is output when the power is turned on or when the channel is switched, and there is a problem that the convenience for the user is lacking. there were.

  Accordingly, the present invention has been made to solve such a problem, and an object of the present invention is to obtain a digital broadcast receiver that shortens the time until video / audio is output when power is turned on or when a channel is switched.

  The digital broadcast receiver according to the present invention is a digital broadcast receiver capable of receiving a digital broadcast and an analog broadcast. The digital broadcast receiver decodes the encoded digital broadcast signal, and demodulates the modulated analog broadcast signal. Analog broadcast demodulating means, switching means for selecting and outputting the digital broadcast signal from the digital broadcast decoding means and the analog broadcast signal from the analog broadcast demodulating means, and at power-on or channel switching, And a control unit that controls the switching means to output an analog broadcast signal.

  As described in claim 1, since the analog broadcast video / audio is output prior to the digital broadcast when the power is turned on, the video / audio is output as early as the conventional analog broadcast receiver. There is an effect that the convenience of the user is not impaired.

[Embodiment 1]
First, data processing of digital broadcasting which is a premise of the present invention will be described. In digital broadcasting, video and audio are encoded according to the MPEG-2 video standard and MPEG-2 audio standard, and the encoded video and audio encoded data are multiplexed according to the MPEG-2 system standard. It is modulated by and broadcast on the broadcast radio wave.

  FIG. 1 is a diagram showing a configuration of encoded data in the MPEG-2 system standard. Video and audio are stored in a packet called PES (Packetized Elementary Stream) for each unit of decoding and reproduction, and are a unit for managing the time of media reproduction. For example, in the case of video, encoded data for one image frame is often used as one PES packet. The PES packet is divided into a plurality of TS (Transort Stream) packet payloads having the same PID (Packet ID) number and transmitted. Information of a plurality of PES packets is not included in one TS packet.

  A TS is composed of TS packets having a fixed length of 188 bytes, and is used in a real-time transmission / communication system including digital broadcasting. Each TS packet has a fixed header part of 4 bytes, and the remaining 184 bytes are composed of a payload part. There is a PID in the header, which enables packet identification.

  In the MPEG-2 system standard, table information representing a relationship with elements such as video and audio constituting a program transmitted by TS is defined. This table information is called PSI (Program Specific Information), and four types of tables such as PAT (Program Association Table) and PMT (Program Map Table) are defined. PSI such as PAT and PMT is transmitted by being arranged in the payload in the TS packet.

  FIG. 2 is a diagram showing the relationship between PAT and PMT in PSI. PAT describes PID of PMT corresponding to the program, and PMT describes PID of video, audio and PCR (Program Clock Reference) included in the corresponding program, so refer to PAT and PMT As a result, only TS packets constituting the target program can be extracted from the TS.

  PCR transmitted in TS packets is periodically transmitted as a time stamp of 27 MHz. The reference time on the transmission side can be reproduced by causing the 27 MHz system clock on the receiver side to PLL (Phase Locked Loop) with reference to the PCR value.

  Video and audio have decoding / playback units, and each unit has a time stamp indicating where to decode and playback at the reference time, and PTS (Presential Time Stamp), DTS (DTS ( Decoding Time Stamp). PTS is time information for performing reproduction, and DTS is time information for performing a decoding operation. In the present invention, the decoded video data and audio data are displayed as video and audio when the time stamp value reproduced with reference to the PCR value matches the PTS. These time stamps can synchronize video and audio.

  FIG. 3 is a diagram showing the configuration of the digital broadcast receiver according to Embodiment 1 of the present invention. The digital broadcast receiver according to the present invention can receive both digital broadcasts and analog broadcasts, and automatically selects and outputs the video / audio of either one of the programs.

  The digital broadcast receiver includes an antenna 1, a distributor 2, a digital broadcast decoding unit 100, an analog broadcast demodulation unit 200, a switching unit 300, a control unit 9, a video device 15, a speaker 17, and a nonvolatile memory 18.

  The antenna 1 can receive both analog broadcasting and digital broadcasting, and is, for example, a commercially available Yagi / Uda antenna. The distributor 2 distributes and outputs the received analog broadcast and digital broadcast.

  The digital broadcast decoding means 100 includes an RF tuner 3 that receives a digital broadcast program having a set frequency, an OFDM demodulator 4 that demodulates a digital broadcast signal modulated by the OFDM method and restores it to a TS packet, and a plurality of multiplexed data. Separating TS packet, extracting PAT and PMT, and restoring video TS and audio TS to PES respectively, TS demultiplexing unit 5 that decodes the encoded PES packet and extracts the video signal, code An audio decoding unit 7 that decodes the converted PES packet to extract an audio signal, a delay circuit 8 that adds a delay amount to the audio signal and synchronizes the audio signal and the video signal, a memory 10 used for decoding processing, and a PCR A system clock 11 for reproducing a system clock synchronized with the sending side by PLL is provided.

  The analog broadcast receiver 200 includes an RF tuner 3 that receives an analog broadcast program having a set frequency, a video demodulator 12 that demodulates the modulated video signal, and an audio demodulator 13 that demodulates the modulated audio signal.

  The switching means 300 is a switch that selects and outputs the digital broadcast signal from the digital broadcast decoding means 100 and the analog broadcast signal from the analog broadcast demodulation means 200, and outputs either analog broadcast video restoration data or digital broadcast video restoration data. A video switch 14 for enabling one of the inputs and an audio switch 16 for enabling either one of the analog restored audio data or the digital restored audio data are provided.

  The control unit 9 sets a reception frequency in the RF tuner 3 in order to view the digital broadcast and the analog broadcast. In the digital broadcast, the display time information of the video to be displayed on the video device 15 from the TS separation unit 5 is set in the PES packet. Obtained from the PTS and DTS described in the header part, calculates the audio delay amount for synchronizing the video and audio, and sets them in the delay circuit 8.

  The video device 15 is a component or device that displays the video restoration data output from the switching means 300 such as a liquid crystal panel, plasma display, or cathode ray tube so that a person can recognize it as a video.

  The speaker 17 is a component or device that outputs sound restoration data output from the switching unit 300 so that a person can recognize it as sound.

  The nonvolatile memory 18 stores information to be stored even when the power is turned off, such as channel information for digital broadcasting and analog broadcasting for each broadcasting station, channel information set before power-on, and the like.

  Next, operations will be described by taking terrestrial digital broadcasting and terrestrial analog broadcasting as examples. The TV broadcast channel is a number assigned to each allocated frequency band of the TV broadcast. VHF waves are composed of 1 to 12 channels, UHF waves are composed of 13 to 62 channels, and SHF waves (for difficult viewing areas) are composed of 63 to 80 channels. Terrestrial digital broadcasting is assigned to channels 13 to 52, and terrestrial analog broadcasting is assigned to channels 1 to 62.

  The control unit 9 sets a reception frequency in the RF tuner 3 in order to select a channel of a broadcast station program to be viewed. Until the terrestrial analog broadcasting is finished, the broadcasting company is carrying out simultaneous broadcasting that simultaneously broadcasts the same program by analog broadcasting and digital broadcasting, and the control unit 9 is provided for each of the analog broadcasting channel and the digital broadcasting channel. Set the assigned reception frequency.

  First, operations from receiving a digital broadcast to outputting it to the video device 15 and the speaker 17 will be described. The control unit 9 sets a reception frequency in the RF tuner 3 to select a channel of a broadcast station program to be viewed, and receives a digital broadcast program having a set frequency via the antenna 1 and the distributor 2. . The received digital broadcast is demodulated by the OFDM demodulator 4 and restored to a TS packet. The TS separator 5 extracts the PAT and PMT, and the controller 9 reads them. The control unit 9 recognizes the video data, audio data, and PCR PID to be decoded by analyzing the PAT and specifying the PMT, and the video decoding unit 6 and the audio decoding unit 7 store the PID information of the TS packet to be decoded. Set. Further, the control unit 9 restores the video TS and the audio TS to the PES and extracts the PTS. Further, the system clock 11 is PLLed by PCR and the system clock synchronized with the transmission side is reproduced.

  Here, the video decoding unit 6 performs video signal processing using the memory 10 to generate video restoration data. Similarly, the voice decoding unit 7 performs voice decoding processing using the memory 10 to generate voice restoration data. The control unit 9 uses the reproduced time stamp, and sets the difference until the time stamp value at which the audio decoding is completed becomes the PTS value in the delay circuit 8 as a delay amount.

  The restored video signal is output to the video device 15, and the restored audio signal is added with a delay amount by the delay circuit 8, synchronized with the video signal, and output to the speaker 17.

  Next, operations from receiving an analog broadcast to outputting it to the video device 15 and the speaker 17 will be described. The control unit 9 sets a reception frequency in the RF tuner 3 in order to select a channel of a broadcast station program to be viewed, and receives an analog broadcast program having a set frequency via the antenna 1 and the distributor 2. . The received analog broadcast is restored to video restoration data and audio restoration data by the video demodulation unit 12 and the audio demodulation unit 13. The video restoration data is output to the video device 15, and the audio restoration data is output to the speaker 17.

  Here, since it takes time to encode and decode video / audio in digital broadcasting, it takes longer to reproduce video and audio than analog broadcasting. Therefore, the feature of the present embodiment is that the controller 9 reads the channel information of the analog broadcast and the digital broadcast from the nonvolatile memory 18 when the digital broadcast receiver is turned on, sets the frequency in the RF tuner 3, and then performs PCR. The video switch 14 and the audio switch 16 are controlled so that the video and audio of the analog broadcast are valid until the time stamp value reproduced with reference to the value of PTS becomes the value of PTS. Further, when the time stamp value reproduced with reference to the PCR value of the digital broadcast becomes the PTS value, the control unit 9 switches the video switch 14 and the audio switch 16 so that the video and audio output of the digital broadcast becomes valid. This is the point to control.

  Further, immediately after switching the channel, the control unit 9 switches the video switch 14 and the audio switch 16 so that the video and audio output of the analog broadcast becomes valid, and the time stamp value reproduced with reference to the PCR value of the digital broadcast When the value becomes the value of PTS, the control unit 9 controls to switch the video switch 14 and the audio switch 16 so that the digital broadcast video and audio output becomes valid again.

  Next, the time relationship between the data processing for analog broadcasting and the data processing for digital broadcasting will be described. Since the detailed operation is as described above, the description thereof is omitted. FIG. 4 is a diagram showing the flow and time relationship on the sending side of analog broadcasting and digital broadcasting. First, processing of digital broadcasting will be described. The video and audio input at the input time T1 are encoded for each video and audio in the playback unit, and a PES packet is generated. The generated packet is separated into TSs, multiplexed with TSs of other programs, and then OFDM modulated and transmitted. Next, analog broadcast processing will be described. The video and audio input at the input time T1 are transmitted after amplitude modulation and frequency modulation, respectively.

  In analog broadcasting, the time required for amplitude modulation and frequency modulation is very short compared to the processing time of encoding, multiplexing, and OFDM modulation of digital broadcasting, so that no time delay occurs compared to digital broadcasting.

  FIG. 5 is a diagram showing the flow and time relationship on the receiving side of analog broadcasting and digital broadcasting. First, processing of digital broadcasting will be described. The received digital broadcast is restored to TS by OFDM demodulation and decoded for each video and audio. The audio decoding data is delayed to synchronize with the video. In analog broadcasting, modulated video / audio is demodulated. As described above, in digital broadcasting, it takes time to perform OFDM demodulation, TS separation, and decoding processing, so that it is possible to reproduce analog broadcast video and audio, digital broadcast audio, and video in this order.

  As shown in FIG. 5, it can be understood that it takes time to reproduce a digital broadcast as compared with an analog broadcast. Therefore, in this embodiment, the analog broadcast is selected and reproduced during the analog broadcast video / audio selection period (from the time when the analog broadcast can be reproduced to the time when the digital broadcast can be reproduced). Also, during the digital broadcast video / audio selection period (the time when the digital broadcast can be reproduced), the digital broadcast is reproduced by automatically switching to the digital broadcast.

  In this way, when the power is turned on or when the channel is switched, the video / audio can be output as fast as the conventional analog broadcast receiver by outputting the video / audio of the analog broadcast before the digital broadcast. There is an effect that the convenience of the user is not impaired.

[Embodiment 2]
FIG. 6 is a configuration diagram of a digital broadcast receiver according to Embodiment 2 of the present invention. The difference from the first embodiment is that a video generation unit 19 that converts video data such as a still wallpaper such as a landscape or a human image into a format that can be displayed on the video device 15, and a video that writes this video data to the nonvolatile memory 18 The data input unit 20 is further provided. The analog broadcast receiving unit 200 includes an RF tuner 3 that receives an analog broadcast program having a set frequency and an audio demodulation unit 13 that demodulates a modulated audio signal. Since other configurations are the same as those of the first embodiment, description thereof is omitted.

  Next, operations from receiving digital broadcast and analog broadcast to outputting to the video device 15 and the speaker 17 will be described. The nonvolatile memory 18 stores video data such as a still wallpaper such as a landscape or a human image, for example, and this video data is read by the video generator 19 and converted into a format that can be displayed on the video device 15. After the power is turned on, the control unit 9 reads the channel information of analog broadcasting and digital broadcasting from the nonvolatile memory 18, sets the frequency in the RF tuner 3, and then the time stamp value reproduced by referring to the PCR value is the value of the PTS. The video switch 14 is set so that the output of the video generation unit 19 is output to the video device 15 until.

  By controlling in this way, image data generated by the video generation unit 19 and analog audio are output until switching to digital broadcast video and audio. The image data generated by the image generation unit 19 can be changed by writing the image data from the video data input unit 20 to the nonvolatile memory 18.

  From the above, since the analog broadcast sound and the video data stored in the non-volatile memory 18 are output before the digital broadcast when the power is turned on, the user can continue until the digital broadcast video / audio is output. There is an effect of not impairing convenience.

  As an application example of the present invention, it can be applied to a digital broadcast receiver.

It is a block diagram of the encoded data in the MPEG-2 system standard. It is the figure which showed the relationship between PAT and PMT. It is the figure which showed the structure of the receiver in Embodiment 1 of this invention. It is the figure which showed the flow and the time relationship of the process by the side of transmission of analog broadcasting and digital broadcasting. It is the figure which showed the flow and the time relationship of the process by the side of the receiver of analog broadcasting and digital broadcasting. It is the figure which showed the structure of the receiver in Embodiment 2 of this invention.

Explanation of symbols

  1 antenna, 2 distributor, 3 RF tuner, 4 OFDM demodulator, 5 TS separator, 6 video decoder, 7 audio decoder, 8 delay circuit, 9 controller, 10 memory, 11 system clock, 12 video demodulator , 13 Audio demodulation unit, 14 Video switch, 15 Video device, 16 Audio switch, 17 Speaker, 18 Non-volatile memory, 19 Video generation unit, 20 Video data input unit, 100 Digital broadcast decoding unit, 200 Analog broadcast demodulation unit, 300 Switching means.

Claims (6)

A digital broadcasting receiver capable of receiving digital broadcasting and analog broadcasting,
A digital broadcast decoding means for decoding the encoded digital broadcast signal;
Analog broadcast demodulation means for demodulating the modulated analog broadcast signal;
Switching means for selecting and outputting the digital broadcast signal from the digital broadcast decoding means and the analog broadcast signal from the analog broadcast demodulation means;
A digital broadcast receiver comprising: a control unit that controls switching means so as to output the analog broadcast signal when the power is turned on or when the channel is switched. The digital broadcast decoding means includes
An audio decoding unit for decoding an audio signal from the encoded digital broadcast signal;
A video decoding unit for decoding a video signal from the encoded digital broadcast signal;
A delay circuit that adds a delay amount to the audio signal and synchronizes the audio signal and the video signal; and
2. The digital broadcast reception according to claim 1, wherein the control unit controls the switching unit to switch the output from the analog broadcast signal to the digital broadcast signal at a timing when the synchronization of the audio signal and the video signal is completed. Machine.   3. The digital broadcast receiver according to claim 2, wherein each channel of the analog broadcast signal and the digital broadcast signal switched by the switching means is a channel of the same broadcast program in simulcast. The analog broadcast demodulation means includes
An audio demodulator that demodulates an audio signal from the modulated analog broadcast signal;
A video demodulator that demodulates a video signal from the modulated analog broadcast signal,
4. The digital broadcast receiver according to claim 1, wherein when the power is turned on or when the channel is switched, the audio signal and video signal of the analog broadcast are output from the switching unit. A non-volatile memory for storing video data;
A video generation unit that converts the video data into a predetermined format and outputs the video data to the switching unit;
The analog broadcast demodulation means includes
An audio demodulator that demodulates an audio signal from the modulated analog broadcast signal;
4. The digital broadcast receiver according to claim 1, wherein when the power is turned on or when the channel is switched, the audio signal of the analog broadcast and the video signal of the video generation unit are output from the switching unit. A video data input unit for writing video data to the nonvolatile memory;
The digital broadcast receiver according to claim 5, wherein the data of the video generation unit is rewritable.

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