JP2008154062A - Broadcast receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve a performance improvement of a broadcast receiver while providing a better viewing/listening environment by asynchronously executing switching control of each video signal and each sound signal in fixed reception and partial reception respectively. <P>SOLUTION: The broadcast receiver is composed of a broadcast reception/demodulation part 11, which receives a broadcast-wave signal related to fixed reception and that of related to partial reception so as to demodulate them, a reception/demodulation state detection part 12 for detecting reception/demodulation states of the broadcast-wave signal, a video/sound decoding part 13 for decoding to a video signal and a sound signal from the demodulated broadcast-wave signal, a video/sound switching control part 15, which generates a control signal for asynchronously switching the video signal and the sound signal on the basis of the reception/demodulation states of the broadcast-wave signal, and a video/sound switching part 16 that asynchronously switches the video signal and the sound signal, which are outputted from the video/sound decoding part, respectively on the basis of the control signal. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a broadcast receiving apparatus having a function of switching reception between a fixed broadcast and a portable / mobile broadcast, particularly suitable for use in an in-vehicle digital broadcast receiving apparatus.

Taking the terrestrial digital TV as an example, the reception switching function of the above-described fixed broadcast and portable / mobile broadcast will be described. For example, as shown in FIG. 11, the terrestrial digital television broadcast divides the frequency band of one channel into 13 segments, and each segment is assigned to fixed and mobile / mobile broadcasts. Sent from
For example, as shown in FIG. 12, in the broadcasting for fixed use, the broadcasting form is a high-definition broadcasting form using 12 segments, or the 12 segments are divided into three to realize three standard-definition broadcasting forms. On the other hand, in broadcasting for mobile and mobile objects, a form of complementary broadcasting (simple moving image) using one segment is realized. Thus, in terrestrial digital television broadcasting, various broadcasting forms can be realized in a frequency band of one channel by segment assignment.

Since the information amounts of these broadcast forms are different, for example, as shown in FIG. 13, segment allocation is performed on one channel according to the broadcast form to enable broadcasting by a plurality of transmission methods. This transmission method is called hierarchical transmission.
For example, in a high-definition broadcast for fixed broadcasting that occupies 12 segments, a large amount of information is transmitted using a 64 QAM (Quadrature Amplitude Modulation) modulation method. On the other hand, in complementary broadcasting (simple moving image) for mobile and mobile broadcasting that can occupy only one segment, transmission is performed using a QPSK (Quadrature Phase Shift Keying) modulation method with a reduced amount of information. Here, on the broadcast receiving device side, reception of a broadcast signal for fixed use is fixed reception, whereas reception of a broadcast signal for portable / mobile objects is called partial reception (for example, see Non-Patent Documents 1 and 2).

The broadcast signal of each broadcast form described above is proportional to the number of allocated segments, and the amount of information transmission per unit time increases. Therefore, high-definition video can be viewed with high-definition broadcasting for fixed broadcasting, but only low-resolution video can be viewed with broadcasting for portable / mobile objects.
On the other hand, paying attention to the performance of the receiving apparatus, the received signal C / N (Carrier Noise Ratio), that is, the required C / N, which is necessary to prevent a reception error from occurring due to a difference in information transmission speed is also different. As the receiving device performance, the higher the information transmission speed, the higher the required C / N. Therefore, higher fixed C / N is required for fixed broadcasting than for mobile / mobile broadcasting. Accordingly, the reception power necessary for preventing a reception error from occurring is also larger in the fixed broadcasting. From the viewpoint of the receivable range, the broadcast reception for portable / mobile objects can be received in a wider range than the broadcast reception for fixed use.

By the way, in mobile receivers such as in-vehicle digital broadcast receivers, the required C / N can be secured by applying diversity technology against received power fluctuations (fading), and fixed broadcast signals can be received. However, reception errors occur in the low reception power area due to performance limitations.
At this time, in the case of a broadcast signal for portable / mobile objects, the required C / N is low even with the same reception power, so that reception is possible without occurrence of a reception error. Therefore, although the video resolution is lowered by switching the reception to the portable / mobile broadcast when the reception state of the fixed broadcast is deteriorated, the performance of the broadcast receiving apparatus can be improved because the viewing can be continued.

  Many patent applications have been filed for the reception switching function described above. For example, a receiving device detects a reception state while acquiring reception C / N, etc., and broadcasts that simultaneously switch video and audio signals for fixed broadcasting and video and audio signals for mobile / mobile broadcasting according to the reception state A receiving apparatus is known (see, for example, Patent Documents 1 and 2). There is also known a broadcast receiving apparatus that switches between fixed broadcast video and audio signals and portable / mobile broadcast audio signals in accordance with the reception state (see, for example, Patent Document 3).

JP 2000-228765 A JP 2004-166173 A JP-A-2005-244531 New era of digital terrestrial digital broadcasting to be known, NHK Reception Technology Center, published in 2003 Digital Broadcasting Handbook, edited by the Institute of Image Information and Television Engineers, Ohmsha, published in 2003

  According to the technology disclosed in each of the above-mentioned patent documents, it is possible to provide a service that can suppress image disturbance as much as possible when the reception state deteriorates by the reception switching function. However, when switching from fixed broadcast reception (fixed reception) to mobile / mobile broadcast reception (partial reception), the video resolution decreases or video output is disabled. As described above, even when switching from fixed reception to partial reception to suppress the occurrence of reception errors, the video resolution is lowered, the screen display is rough, and the state of being difficult to see is not sufficient as the performance of the digital broadcast receiving apparatus.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a broadcast receiving apparatus that improves the performance of the broadcast receiving apparatus by providing a better viewing environment.

  A broadcast receiving apparatus according to the present invention includes a broadcast reception / demodulation unit that receives and demodulates a broadcast wave signal related to fixed reception and partial reception, and a reception / demodulation state detection unit that detects a reception / demodulation state of the broadcast wave signal A video / audio decoding unit that decodes the demodulated broadcast wave signal into a video signal and an audio signal, and a control signal that asynchronously switches the video signal and the audio signal based on the reception / demodulation state of the broadcast wave signal. A video / audio switching control unit to be generated, and a video / audio switching unit that asynchronously switches each of the video signal and audio signal output from the video / audio decoding unit based on the control signal. It is.

  According to the present invention, it is possible to improve the performance of the broadcast receiving apparatus by providing a better viewing environment by switching and controlling the video signal and the audio signal in the fixed reception and the partial reception asynchronously.

Embodiment 1 FIG.
1 is a block diagram showing an internal configuration of a broadcast receiving apparatus according to Embodiment 1 of the present invention. The broadcast receiving apparatus according to Embodiment 1 of the present invention includes a broadcast receiving / demodulating unit 11, a receiving / demodulating state detecting unit 12, a video / audio decoding unit 13, a video / audio decoding state detecting unit 14, and a video An audio switching control unit 15, a video / audio switching unit 16, a video output unit 17, an audio output unit 18, a video monitor 19, and a speaker 20.

The broadcast receiving / demodulating unit 11 has a function of receiving and demodulating a broadcast wave signal, and includes a receiving antenna 110, a receiving tuner 111, a demodulator 112, and a transport stream (TS) reproducing unit 113. The demodulator 112 includes hierarchical demodulator units # 1 to #N (112a to 112n, respectively). The reception / demodulation state detection unit 12 detects the reception / demodulation state of the broadcast wave signal from the output of the broadcast reception / demodulation unit 11 and outputs it to the video / audio switching control unit 15.
On the other hand, the video / audio decoding unit 13 has a function of decoding a demodulated broadcast wave signal into a video signal and an audio signal, and includes a TS demultiplexing unit 130, a PTS (Presentation Time Stamp) synchronization unit 131, and an MPEG- 2 (Moving Picture Element Group-2) video decoder 132; H.264 video decoder 133, audio decoder A134, and audio decoder B135. The video / audio decoding state detection unit 14 detects the decoding state of the video signal and the audio signal output from the video / audio decoding unit 13 and outputs them to the video / audio switching control unit 15.

  The video / audio switching control unit 15 receives the video signal based on either the reception / demodulation state output from the reception / demodulation state detection unit 12 or the video / audio decoding state detection unit 14, or the decoding state, or both. A control signal for asynchronously switching the audio signal is generated and output to the video / audio switching unit 16. The video / audio switching unit 16 has a function of asynchronously switching each of the video signal and the audio signal output from the video / audio decoding unit 13 based on the control signal generated by the video / audio switching control unit 15. It comprises a video switcher 16a and an audio switcher 16b.

  The video output unit 17 outputs the video signal output from the video / audio switching unit 16 to the video monitor 19 to perform video reproduction, and the audio output unit 18 receives the audio signal output from the video / audio switching unit 16. It outputs to the speaker 20 and performs audio | voice reproduction | regeneration.

  The difference between synchronous control and asynchronous control will be described with reference to FIG. FIG. 2 illustrates the video / audio switching state with respect to the reception state. In the upper part, the reception state is divided into five phases. To explain in order, Phase 1 has no fixed broadcast reception error, Phase 2 has fixed broadcast reception error, Phase 3 has exceeded the fixed broadcast reception error tolerance, No mobile / mobile broadcast reception error, Phase 4 has mobile・ Mobile reception error occurred for mobiles, phase 5 reception is disabled.

The middle part shows synchronous control. When a reception error occurs in broadcasting for fixed use, when the reception error switching threshold of the broadcast receiving apparatus is exceeded, switching to a video / audio signal for broadcasting for portable / mobile objects is performed. At this point, the resolution of the video signal decreases.
The lower part shows asynchronous control. For example, if a reception error occurs in a fixed broadcast signal, the video signal will be the same as the fixed broadcast video signal and audio signal, and the mobile / mobile broadcast video signal and audio signal. With error correction, video output with as high a resolution as possible is continued within the allowable range of screen error, and then switched to broadcast video for mobile / mobile, while the audio signal for fixed broadcast suppresses noise and interruptions as much as possible. Therefore, it is possible to switch to the audio signal for broadcasting for mobile / mobile objects at an early point.

Here, the operation of the broadcast receiving apparatus according to the first embodiment configured as shown in FIG. 1 will be described. The broadcast wave signal hierarchized by segment allocation is received by the receiving antenna 110, further frequency-converted to an IF (intermediate frequency) signal by the receiving tuner 111, and input to the demodulator 112. The IF signal input to the demodulator 112 is input to the hierarchical demodulator # 1 (112a) to the hierarchical demodulator #N (112n), and each of the hierarchized broadcast wave signals is individually demodulated to the TS reproducing unit 113. Output to. At the same time, hierarchical transmission scheme information of each signal and signals related to reception and demodulation states such as reception signal level, reception C / N, and reception error are generated and output to the reception / demodulation state detection unit 12.
Note that the hierarchical demodulated signals output to the TS reproduction unit 113 are multiplexed and output to the video / audio decoding unit 13.

In the video / audio decoding unit 13, the TS signal multiplexed and output from the broadcast receiving / demodulating unit 11 is output by the TS demultiplexing unit 130 with four types of ES (Elementary Stream) and PCR (Program Clock Reference: program time). Separated to standard value) and output. The first ES is a video signal ES transmitted using 12 segments for fixed broadcasting, and the MPEG-2 video ES and the second ES are audio (audio) ES transmitted in the same hierarchy. It is. The third ES is a video signal ES transmitted using one segment for mobile / mobile broadcasting. The H.264 video ES and the fourth ES are audio (audio) ESs transmitted in the same hierarchy. Each ES is added with a time stamp indicating the decoding timing by the PTS synchronization unit 131 before being decoded by the corresponding decoder.
The PTS synchronization unit 131 uses the PCR output from the TS demultiplexing unit 130 to synchronize with an STC (System Time Clock), which is a reference clock inside the broadcast station, which transmits a broadcast signal in the STC reproduction block, and at that timing Operates according to the above.

  The MPEG-2 video ES and the audio ES are decoded into a video signal by the MPEG-2 video decoder 132 and an audio signal by the audio decoder A134, respectively. H. H.264 video ES and audio ES are respectively H.264 and H.264. The H.264 video decoder 133 decodes the video signal and the audio decoder B135 decodes the video signal. The decoded signals are output to the video / audio switching unit 16 and the decoding error states in the decoders 132 to 135 are sent to the video / audio decoding state detection unit 14.

  Broadcast wave reception demodulation errors and video / audio signal decoding errors output from the reception / demodulation state detection unit 12 and the video / audio decoding state detection unit 14 are sent to the video / audio switching control unit 15. The video / audio switching unit 16 switches the video and audio signals asynchronously in accordance with the control of the video / audio switching control unit 15, and the video and audio signals after the switching are the video output unit 17 and the audio output unit 18, respectively. Is output. The video signal output from the video output unit 17 is output as a video via a video monitor 19, and the audio signal output from the audio output unit 18 is output as a sound via a speaker 20.

  Here, a video / audio switching control method will be described. The video / audio switching control unit 15 displays the state of the broadcast wave reception demodulation error output from the reception / demodulation state detection unit 12 or the video / audio signal decoding error output from the video / audio decoding state detection unit 14 as video. The switching threshold determination level for each of the signal and the audio signal is compared and determined, and the video / audio switching by the video / audio switching unit 16 is controlled asynchronously according to the determination result.

FIG. 3 is a flowchart showing an example of switching control from a fixed broadcast video signal to a portable / mobile broadcast video signal. The reception / demodulation error rate EV ₁ output from the reception / demodulation state detector 12 while the broadcast receiver starts receiving broadcast waves (step ST201) and outputs a fixed broadcast video signal (step ST202). Is zero (step ST203 “NO”), the video / audio switching control unit 15 performs control so as to continue the state of step ST201. Further, the switching threshold determination level EV _{F / E,} if it becomes EV ₁ <EV _{F / E} is determined (Step ST204 "NO"), fixed for the broadcast video signal is not suitable for viewing, mobile Switch to moving body video output (step ST212). On the other hand, when it is determined that 0 <EV ₁ <EV _{F / E} (step ST204 “YES”), that is, an allowable range for viewing using the error correction (error concealment control) function of the MPEG-2 video decoder 132. It determined, and then the process proceeds to step ST205, and controls on the basis of a video signal decoding error rate EV ₂ in MPEG-2 video decoder 132 by video and audio decoding state detector 14.

Here, the error concealment control of the MPEG-2 video decoder 132 will be described. As shown in FIG. 4, the MPEG-2 video coding has a five-layer structure, and is called a block, a macroblock, a slice, a picture, and a sequence in order from the bottom. This is also disclosed in pages 33 to 34 of Non-Patent Document 2.
Error concealment control is performed in an upper layer above the slice. Here, control in the slice layer is referred to as slice mode, control in the picture layer is referred to as picture mode, and control in the sequence layer is referred to as sequence mode.

As shown in FIG. 5, the slice mode controls a unit composed of an arbitrary number of macro blocks arranged in a horizontal line in the screen as a minimum unit of error control. Noise on the display screen is determined by the presence or absence of errors in slice units. Therefore, the lower the video signal decoding error rate EV _2, screen noise portion is small, it does not follow that hardly viewed. However, since the number of screen noise increases as EV ₂ increases, the picture mode is applied as the error concealment control means.
In the picture mode, a frame including a picture in which an error has occurred is not displayed, and the state is maintained (stopped) on the screen before the error occurrence display until it is updated to the next picture frame without an error. The sequence mode is the same control method as the picture mode. However, since the sequence mode is controlled not in the picture frame but in the sequence unit, the screen update time becomes longer and the screen stop time tends to become longer.

Returning to the flowchart of FIG. 3, assuming that the video signal switching determination threshold is the slice mode allowable error rate EV _S , the picture mode allowable error rate EV _P and the sequence mode allowable error rate EV _Sq , the state of step ST205 Thus, as the error rate EV ₂ increases, control is performed from the slice mode (step ST207) for fixed broadcast video to the picture mode (step ST209: EV ₂ > EV _S ) → sequence mode (step ST211: EV ₂ > EV _P ). It is, when the image of the finally fixed for broadcasting becomes difficult to see, switching to mobile-mobiles broadcast video (step _{ST212: EV 2> EV Sq)} .

  The flowchart shown in FIG. 3 is an example of video switching control, and the video / audio switching control unit 15 switches from each error concealment control mode state of the MPEG-2 video decoder to a broadcast video for mobile / mobile. It is possible to control.

Next, audio signal switching control will be described with reference to the flowchart shown in FIG. The video / audio switching control unit 15 causes the error rate notified from the reception / demodulation state detection unit 12 when the broadcast receiving apparatus starts receiving broadcast waves (step ST501), and in a fixed broadcast audio output state (step ST502). When EA ₁ is zero (step ST503 “NO”), the state of step ST502 is continued. If the switching threshold determination level EA _{/ F} is EA ₁ > EA _{F / E} (step ST504 “NO”), it is determined that the fixed broadcast video signal is not suitable for viewing, and the portable Switch to moving body video output (step ST508). On the other hand, if 0 <EA ₁ <EA _{F / E} (step ST504 “YES”), that is, using the error concealment control function of the audio decoder A134, it is determined that noise and sound interruptions are in an allowable range, and are fixed. The broadcast audio error concealment control mode (step ST505) is entered, and if EA ₂ <EA _EC (step ST506 “YES”), the error rate EA _EC for audio signal error concealment is acceptable (step ST506 “YES”). If the error rate EA2 of the audio decoder A134 is EA ₂ > EA _EC (step ST506 “NO”), the voice signal is switched to a portable / mobile audio signal (step ST508).

According to the first embodiment described above, when receiving a broadcast wave, the reception / demodulation state of the reception / demodulation state detection unit 12 is used to asynchronously transmit the video signal and audio signal of the fixed broadcast and the portable / mobile broadcast. By switching, even when reception and decoding conditions deteriorate, both high-resolution video for fixed broadcasts and noise and uninterrupted audio output for mobile and mobile broadcasts can be provided to provide better viewing conditions. it can.
Also, using the decoding state by the video / audio decoding state detection unit 14 or the state detection result by the combination of the decoding state and the reception / demodulation state, the video signal and audio of the fixed broadcast and the portable / mobile broadcast By switching signals asynchronously, more accurate video / audio switching control can be realized.

Embodiment 2. FIG.
FIG. 7 is a block diagram showing an internal configuration of the broadcast receiving apparatus according to Embodiment 2 of the present invention. When the audio signals of the fixed broadcast and the portable / mobile broadcast can be decoded by the same decoding method (shared by the audio decoder C (138)), the audio of the video / audio decoding unit 13 as in the first embodiment. Rather than switching the signal output by the audio switching unit 16b, two ESs are switched by the audio ES switching unit 137 connected between the TS demultiplexing unit 130 and the PTS synchronization unit 131 inside the video / audio decoding unit 13. It is also possible to switch.

In this case, the switching output of the audio ES switching unit 137 is voice-decoded by the audio decoder C 138 via the PTS synchronization unit 131 and outputted to the speaker 20 via the voice output unit 18. Other configurations are the same as those in the first embodiment.
As in the first embodiment shown in FIG. 1, the audio ES switching unit 137 is switched by the video / audio switching control unit 15 based on the state detection results by the reception / demodulation state detection unit 12 and the video / audio decoding state detection unit 14. Be controlled. Asynchronous switching control between the video signal and the audio signal by the video / audio switching control unit 15 is the same as the procedure shown in the flowcharts of FIGS.

  According to the above-described second embodiment, in addition to the effects of the first embodiment, the circuit scale can be reduced, which is advantageous in terms of mounting and cost compared to the first embodiment.

Embodiment 3 FIG.
FIG. 8 is a block diagram showing the internal configuration of the broadcast receiving apparatus according to Embodiment 3 of the present invention. The difference from the first embodiment shown in FIG. 1 is that a user interface unit composed of a user notification control unit 31 and a user instruction unit 32 is further added to the configuration of the first embodiment shown in FIG. The information input / output via the user interface is reflected in the asynchronous switching control of the video signal and the audio signal by the video / audio switching control unit 15.

The user interface unit, here, the user notification control unit 31 notifies the user of the reception state based on the switching control information generated by the video / audio switching control unit 15. For example, an antenna level display indicating a fixed broadcast reception state in accordance with the acquired reception / demodulation state and video / audio decoding state, or switching from a fixed broadcast to a mobile / mobile broadcast due to reception state deterioration An OSD (On Screen Display) can be displayed on the screen of the video monitor 19.
Alternatively, the reception state deterioration may be notified by an alarm sound by sound output, and a notification for urging switching from a fixed broadcast to a portable / mobile broadcast may be performed. At this time, in order to change the threshold used for fixed reception and partial reception switching, it is also conceivable to acquire the switching condition set and input by the user via the user instruction unit 32 and change the threshold.

  According to the third embodiment described above, each error state acquired from the reception / demodulation state detection unit 12 and the video / audio decoding state detection unit 14 by the user interface unit (the user notification control unit 31 and the user instruction unit 32). Based on the above, the switching information is notified to the user, and the user can manually control the switching. Therefore, it is possible to provide an optimum user interface that is easy to use.

Embodiment 4 FIG.
FIG. 9 is a block diagram showing an internal configuration of the broadcast receiving apparatus according to Embodiment 4 of the present invention. The difference from the third embodiment shown in FIG. 8 is that the driving state detection unit 41 is further added to the configuration of the third embodiment shown in FIG. 8, and the video / audio switching control unit 15 performs asynchronous video and audio. The vehicle information is reflected in the switching control.

  When this broadcast receiving apparatus is used for in-vehicle use, by providing the traveling state detection unit 41, asynchronous switching control of video / audio signals is performed according to the traveling state of the vehicle such as the vehicle speed. For example, while traveling, the received power fluctuation is large in a multipath environment, and the possibility of noise and sound interruption increases. Therefore, the traveling state detection unit 41 (for example, a vehicle speed sensor) detects that the vehicle is traveling. In this case, the video / audio switching control unit 15 forcibly executes control for switching to broadcasting for portable / mobile objects. Similarly, when the traveling screen is output on the screen of the video monitor 19 while the vehicle is traveling, the mode is switched to partial reception for portable / mobile objects.

  According to the above-described fourth embodiment, when the present broadcast receiving apparatus is used for in-vehicle use by reflecting the running state of the vehicle in the asynchronous switching control of the video signal and the audio signal by the video / audio signal switching unit 15, It is possible to enjoy a viewing environment that is not affected by multipath and that avoids noise and sound interruption as much as possible.

Embodiment 5. FIG.
FIG. 10 is a block diagram showing an internal configuration of a broadcast receiving apparatus according to Embodiment 5 of the present invention. The difference from the fourth embodiment shown in FIG. 9 is that a delay amount detection / setting unit 21 and a delay correction unit 136 are further added to the configuration of the fourth embodiment. The delay amount detection unit 21 detects the delay amount of the video signal and the audio signal between fixed reception and partial reception from the outputs of the audio decoders A 134 and B 135 constituting the video / audio decoding unit 13, and the delay correction unit 136. Corrects the delay corresponding to the delay amount detected by the delay amount detection / setting unit 21 and outputs a fixed reception video and a partial reception audio signal or a combination of a fixed reception audio signal and a partial reception video signal. Synchronous control between video and audio is performed. The delay correction unit 136 is connected between the PTS synchronization unit 131 constituting the video / audio decoding unit 13 and the video and audio decoder groups 132 to 135.

In the above-described fourth embodiment, a signal is sent from a broadcasting station with a fixed delay amount between signals for both fixed broadcast and portable / mobile mobile broadcast, and the fixed broadcast video signal and portable / movable When an audio signal for a body-oriented broadcast is output, even if no error occurs during reception, the video and audio cannot be synchronized, making it very difficult to view.
Therefore, by providing the delay amount detection / setting unit 21 and the delay correction unit 136, control for synchronizing video and audio is realized, and the above-described problem is solved. Specifically, the delay amount detection / setting unit 21 simultaneously decodes both fixed broadcast and portable / mobile broadcast signals by the video / audio decoding unit 13, and a predetermined level value or more from the decoded signal. The delay amount is detected by comparing the peak value appearance intervals and detecting the relative time difference.

  The detected delay amount is set in the delay amount correction unit 136 from the delay amount detection / setting unit 21, a delay corresponding to the set delay amount is added by the internal delay buffer, and a signal is output to the decoders 132 and 134. Also, the moment of switching from fixed broadcast to mobile / mobile broadcast is performed by executing the mute process in the audio output unit 18 for the time corresponding to the set delay amount given from the delay amount detection / setting unit 21. It becomes possible to suppress the disturbance of the sound at the time.

  According to the fifth embodiment described above, when there is a delay between the signal for fixed broadcasting and the signal for portable / mobile broadcasting, the amount of delay is detected and corrected so that By switching the video signal and the audio signal for broadcasting asynchronously and synchronizing the video signal and the audio signal even when there is no combination of the signals, the video and the audio can be synchronized and viewed.

In the above-described first to fifth embodiments, the reception / demodulation state detection unit 12, the video / audio decoding unit 13, the video / audio decoding state detection unit 14, and the video / audio switching control unit 15 are A control microcomputer may be used.
In this case, the control microcomputer asynchronously switches the video signal and the audio signal of the fixed broadcast and the portable / mobile broadcast based on the reception / demodulation state or the decoding state according to the program recorded in the built-in memory. By generating control signals and controlling peripheral LSIs, both high-resolution video for fixed broadcasting and noise and uninterrupted audio output for portable and mobile broadcasting can be achieved even when reception and decoding conditions deteriorate. , Provide a better viewing state. Here, the peripheral LSI corresponds to each LSI constituting the broadcast receiving / demodulating unit 11, the video / audio decoding unit 13, and the video / audio switching unit 16, and these are connected via an input / output port built in the control microcomputer. Connected and communicated. At this time, the procedure shown in the flowcharts of FIGS. 2 and 5 is recorded as a program in the built-in memory.

It is a block diagram which shows the internal structure of the broadcast receiver which concerns on Embodiment 1 of this invention. It is the figure quoted in order to demonstrate the state of the video / audio switching with respect to a reception state. It is the flowchart quoted in order to demonstrate operation | movement of the broadcast receiver which concerns on Embodiment 1 shown in FIG. It is the figure quoted in order to demonstrate operation | movement of the broadcast receiver which concerns on Embodiment 1 shown in FIG. It is the figure quoted in order to demonstrate operation | movement of the broadcast receiver which concerns on Embodiment 1 shown in FIG. It is the flowchart quoted in order to demonstrate operation | movement of the broadcast receiver which concerns on Embodiment 1 shown in FIG. It is a block diagram which shows the internal structure of the broadcast receiver which concerns on Embodiment 2 of this invention. It is a block diagram which shows the internal structure of the broadcast receiver which concerns on Embodiment 3 of this invention. It is a block diagram which shows the internal structure of the broadcast receiver which concerns on Embodiment 4 of this invention. It is a block diagram which shows the internal structure of the broadcast receiver which concerns on Embodiment 5 of this invention. It is the figure which showed the segment structure in 1 channel frequency bandwidth of a terrestrial digital television broadcast wave. It is the figure quoted in order to demonstrate the broadcast form in terrestrial digital television broadcasting. It is the figure quoted in order to demonstrate the segment structure of a hierarchical transmission system.

Explanation of symbols

  11 broadcast reception / demodulation unit, 12 reception / demodulation state detection unit, 13 video / audio decoding unit, 14 video / audio decoding state detection unit, 15 video / audio switching control unit, 16 video / audio switching unit, 17 video output unit , 18 Audio output unit, 19 Video monitor, 20 Speaker, 21 Delay amount detection / setting unit, 31 User notification control unit, 32 User instruction unit, 41 Running state detection unit, 110 Receiving antenna, 111 Receiving tuner, 112 Demodulator, 112a to 112n Hierarchical demodulation unit, 113 TS playback unit, 130 TS demultiplexing unit, 131 PST synchronization unit, 132 MPEG-2 video decoder, 133H. H.264 video decoder, 134 audio decoder A, 135 audio decoder B, 136 delay correction unit, 137 audio ES switcher, 138 audio decoder C.

Claims (15)

A broadcast receiving apparatus that receives a broadcast wave signal by switching between fixed reception and partial reception,
A broadcast receiving / demodulating unit for receiving and demodulating the broadcast wave signal;
A reception / demodulation state detection unit for detecting a reception / demodulation state of the broadcast wave signal;
A video / audio decoding unit that decodes the demodulated broadcast wave signal into a video signal and an audio signal;
A video / audio switching control unit that generates a control signal for asynchronously switching the video signal and the audio signal based on the reception / demodulation state of the broadcast wave signal;
Based on the control signal, a video / audio switching unit that asynchronously switches each of the video signal and the audio signal output from the video / audio decoding unit;
A broadcast receiving apparatus comprising: A video / audio decoding state detection unit for detecting a decoding state of the video signal and the audio signal;
The video / audio switching unit generates a control signal for switching the video signal and the audio signal asynchronously based on the decoding state, and the video / audio switching unit receives the control signal from the video / audio decoding unit based on the control signal. 2. The broadcast receiving apparatus according to claim 1, wherein the output video signal and audio signal are switched asynchronously. The video / audio switching unit is
The video / audio switching control unit is configured to receive and demodulate the broadcast wave signal detected by the reception / demodulation state detection unit, and decode the video signal and audio signal detected by the video / audio decoding state detection unit. Each of the video signal and the audio signal output from the video / audio decoding unit is asynchronously switched based on a control signal that is generated by combining the states and asynchronously switches the video signal and the audio signal. The broadcast receiving apparatus according to claim 1 or 2.   2. The video / audio decoding unit switches the audio signal as an alternative to the video / audio switching unit only when audio signals by the fixed reception and partial reception can be decoded by the same method. The broadcast receiving device according to claim 3. A user interface unit that prompts the setting input of the fixed reception and partial reception switching conditions;
The video / audio switching unit, based on the switching condition acquired via the user interface unit, the fixed reception and partial reception for the broadcast wave reception / demodulation state or the video signal / audio signal decoding state. The broadcast receiving apparatus according to any one of claims 1 to 4, wherein the switching condition is changed. The user interface unit includes:
The video / audio switching based on the reception / demodulation state of the broadcast wave signal detected by the reception / demodulation state detection unit or the decoding state of the video signal and audio signal detected by the video / audio decoding state detection unit The broadcast receiving apparatus according to claim 5, wherein control information generated by the control unit is notified to a user. The user interface unit includes:
The broadcast receiving apparatus according to claim 6, wherein the reception / demodulation state or the decoding state is reported on an antenna level display on a monitor screen.   The broadcast receiving apparatus according to claim 6, wherein control information generated by the video / audio switching control unit is displayed on a monitor screen to notify a user.   7. The broadcast receiving apparatus according to claim 6, wherein control information generated by the video / audio switching control unit is notified by audio output. A traveling state detection unit for detecting the traveling state of the vehicle;
2. The video / audio switching control unit asynchronously switches the fixed reception or partial reception video signal and audio signal output from the video / audio switching unit according to the running state. The broadcast receiving device according to claim 9. The video / audio switching control unit
11. The broadcast receiving apparatus according to claim 10, wherein when the traveling state detecting unit detects that the vehicle is traveling, the audio signal is controlled to be switched to partial reception forcibly. A delay amount detection unit for detecting a delay amount of the video signal and the audio signal between the fixed reception and the partial reception;
The delay corresponding to the delay amount is corrected, and synchronization control is performed between video and audio when outputting a fixed reception video and a partial reception audio signal or a combination of a fixed reception audio signal and a partial reception video signal. A delay correction unit;
The broadcast receiving apparatus according to claim 1, further comprising: The delay amount detection unit
2. The delay amount is detected based on a relative time difference by comparing appearance intervals of peak values greater than or equal to a predetermined value from fixed reception and partial reception decoded signals simultaneously decoded by the video / audio decoding unit. 12. The broadcast receiving device according to 12. The delay correction unit includes a delay buffer;
Delaying the decoded signal with the earlier output timing of either fixed reception or partial reception by the delay amount detected by the delay amount detection unit via the delay buffer, and synchronizing the video signal and the audio signal The broadcast receiving apparatus according to claim 12. An audio output unit that performs mute control for the delay amount detected by the delay amount detection unit when the audio signal is switched;
The broadcast receiving apparatus according to claim 12, further comprising:

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