JP2016129303A - Digital broadcast receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a digital broadcast receiver which can reduce time required to output audio when switching digital broadcasting of the same contents.SOLUTION: A digital broadcast receiver comprises RF parts 12, 22 which receive first and second digital broadcast signals to output first and second pieces of audio data; a delay time determination part 42 which compares pieces of audio data of the same contents and determines a temporal shift of the first audio data with respect to the second audio data as a time delay; a buffer 32 which has a predetermined amount of data capacity, and delays the second audio data within a range equal to or less than an upper limit of time corresponding to the data capacity; and a switching suitability determination part 44 which determines whether the second audio data output can be delayed using the buffer 32 for the time delay determined by the delay time determination part 42, on the basis of a bit rate of the second audio data and the data capacity of the buffer 32.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a digital broadcasting receiver that receives program data according to the DAB (Digital Audio Broadcasting) broadcasting standard or the like.

  In Europe, digital broadcasting and analog broadcasting with the same service content (program content) are broadcast simultaneously using digital broadcasting and FM analog broadcasting according to the DAB broadcasting standard, or at different frequencies for each region. There are cases where a plurality of digital broadcasts having the same service content are broadcast simultaneously.

  As a broadcast receiving apparatus corresponding to such broadcast contents, a configuration including both a DAB tuner and an FM tuner is known (see, for example, Patent Documents 1 and 2). In this broadcast receiving apparatus, the audio output timing corresponding to the DAB tuner and the audio output timing corresponding to the FM tuner are matched by adjusting the delay time of the variable delay unit provided on the FM tuner side. Therefore, when the reception state deteriorates while receiving a digital broadcast, it is possible to receive an analog broadcast (FM broadcast) that broadcasts a program with the same content and maintain an audio output (DAB- FM link function).

JP 2002-319873 A Japanese Patent Laid-Open No. 10-247855

  By the way, as described above, when adjusting the delay time of the variable delay unit provided on the FM tuner side, the analog broadcast is delayed within the maximum delay time by setting the maximum delay time of the analog broadcast in advance. do it. However, for example, if two DAB tuners are used and the audio output timing corresponding to one DAB tuner is made to coincide with the audio output timing corresponding to the other DAB tuner, the DAB on the side that delays the audio output It is necessary to store the sound data of the tuner for the delay time, but the data amount of the sound data varies greatly according to the bit rate set on the broadcasting station side, so the memory used for storing the delay time Depending on the capacity, it may not be possible to ensure the actually required delay time. For example, when a memory for 3 seconds capable of supporting a bit rate up to 96 kbit (/ s) is provided, audio data having a bit rate lower than this bit rate can be delayed for 3 seconds. The audio data having a bit rate larger than this bit rate cannot be delayed for 3 seconds. As an extreme example, when the bit rate is 384 kbit, the audio data can be delayed for only 0.7 seconds even if the same capacity memory is used. Therefore, if the reception condition deteriorates while receiving a digital broadcast using one DAB tuner, the digital broadcast of the same content received using the other DAB tuner will be delayed for 3 seconds to maintain the audio output. However, the delay time adjustment for this is not successful and fails, and the time required for the time adjustment is wasted. As a result, there is a problem that the time until the subsequent voice output becomes long. For example, when time adjustment is impossible, it is only necessary to switch to audio output using the other DAB tuner without adjusting time, but when this switching is executed after determining whether or not the time adjustment is successful, The timing of switching is delayed by the time required to determine whether or not the adjustment is successful, and during that time, the user's listening to the program content is interrupted.

  The present invention was created in view of the above points, and an object of the present invention is to provide a digital broadcast receiver that can shorten the time until audio output when switching digital broadcasts of the same content. It is in.

  In order to solve the above-described problems, the digital broadcast receiver according to the present invention is compatible with audio data having the same content as the first receiving means for receiving the first digital broadcast signal and outputting the first audio data. The second receiving means for receiving the second digital broadcast signal and outputting the second audio data is compared with the same audio data output from the first and second receiving means, Delay time determining means for determining a time lag of the first audio data with respect to the audio data as a delay time, and having a predetermined data capacity, and setting the time corresponding to the data capacity of the second audio data to an upper limit value Whether or not it is possible to delay the output of the second audio data by using the delay means for the delay time determined by the delay means determined by the delay means and the delay time determination means. The second And a determining delay determination means based on the data capacity of the bit rate and delay means voice data.

  In particular, the delay time determination is performed when the switching means for switching the voice data from the first receiving means described above to the voice data delayed by the delay means and the delay availability determination means determine that the delay is possible. It is desirable to further include output switching setting means for instructing switching to the switching means after the passage of the delay time determined by the means.

  When switching from the audio output corresponding to the first digital broadcast signal to the audio output corresponding to the second digital broadcast signal having the same content, whether or not it is possible is determined based on the bit rate of the audio data and the data capacity of the delay means. Therefore, the time required for this determination can be shortened and the time until the audio output after switching can be shortened compared to the case where the time adjustment for performing the delay is actually performed and whether or not it is confirmed. Can do.

  Further, it is desirable that the output switching setting unit described above immediately instructs the switching unit to perform switching when the delay availability determination unit determines that the delay is not possible. Thereby, when it is not possible to switch so that the content of the audio output is continuous, it is possible to immediately perform switching that allows the content of the audio output to be discontinuous. In this case, the audio output after switching It is possible to significantly reduce the time until

  In addition, it is desirable that the silence process is performed on the audio data immediately after the switching unit is switched when it is determined that the delay cannot be performed by the delay determination unit. Thereby, it is possible to reduce the uncomfortable feeling that the user feels due to the discontinuity of the contents of the audio output.

  When the delay time determined by the delay time determination means described above is T1, and the upper limit value of the time delayable by the delay means based on the bit rate of the second audio data and the data capacity of the delay means is T2. In addition, it is desirable that the delay availability determination means determine that the delay is possible when the relationship of T1 ≦ T2 is satisfied. Alternatively, when the delay time upper limit value as a fixed value set regardless of the data capacity of the delay means described above is T0, the delay availability determination means satisfies the relationship of T1 ≦ T0 and T1 ≦ T2 It is desirable to determine that delay is possible. As a result, it is possible to determine whether or not delay is possible only by confirming the magnitude relationship between a plurality of types of time, and the processing required for the determination can be simplified.

  The first and second digital broadcast signals described above are preferably digital broadcast signals according to the DAB broadcast standard. Thereby, the present invention can be applied to a digital broadcast receiver as a DAB receiver capable of receiving two digital broadcast signals included in different ensembles.

It is a figure which shows the structure of the digital broadcast receiver of one Embodiment. It is a figure which shows the frame structure of the digital broadcast signal according to DAB / T-DMB broadcast standard. It is a figure which shows the relationship between the bit rate of audio | voice data, and the adjustable range (upper limit value of delayable time) of delay time using a buffer. It is a flowchart which shows the operation | movement procedure which switches the service which has the same content. It is explanatory drawing which shows the effect of the switching of the music data in this embodiment.

  Hereinafter, a digital broadcast receiver according to an embodiment to which the present invention is applied will be described with reference to the drawings. FIG. 1 is a diagram illustrating a configuration of a digital broadcast receiver according to an embodiment. For example, this digital broadcast receiver is for receiving a digital broadcast signal according to the DAB broadcast standard (DAB / T-DMB broadcast standard) mainly used in Europe. The digital broadcast receiver is mounted on a vehicle.

  As shown in FIG. 1, the digital broadcast receiver of this embodiment includes RF units 12 and 22, analog-digital converters (A / D) 14 and 24, decoders 16 and 26, buffers 30 and 32, and reception status determination. Unit 40, delay time determination unit 42, switchability determination unit 44, output switching setting unit 46, identical service search unit 48, switching unit (SW) 50, output processing unit 52, amplifier 54, and speaker 56.

  FIG. 2 is a diagram showing a frame structure of a digital broadcast signal according to the DAB / T-DMB broadcast standard. As shown in FIG. 2, the frame is composed of a synchronization channel, a first information channel FIC, and a main service channel MSC.

  The synchronization channel is composed of a NULL symbol and a phase reference symbol PRS (Phase Reference Symbol), and is used for frame synchronization by detecting the head portion of the frame. The first information channel FIC is an area for explaining the contents of the main service channel MSC, and includes time / date data, service (program) arrangement data, service label (name), service identification code SID (Service Identification). Code). A plurality of FIGs (first information groups) are energy-spread to form one FIB (first information block) which is a predetermined information unit. Each FIB is convolutionally encoded, and the three FIBs subjected to the convolutional coding constitute one FIC. The main service channel MSC mainly includes voice data corresponding to each of a plurality of services. The main service channel MSC includes a plurality of sub-channels (SubCh) that are energy spread, convolutionally encoded, and time interleaved.

  The RF unit 12 converts a digital broadcast signal received via the antenna 10 into an intermediate frequency signal. The analog-digital converter 14 converts an analog intermediate frequency signal into digital data (intermediate frequency data). The decoder 16 performs demodulation processing and decoding processing on the intermediate frequency data to generate audio data for each service, and extracts the bit rate of the audio data. A digital broadcast signal (first digital signal) broadcast by one broadcast station in a multicarrier scheme using OFDM (Orthogonal Frequency Division Multiplexing) as a modulation scheme by the RF unit 12, the analog-digital converter 14, and the decoder 16. (Broadcast signal) is received, demodulation processing and decoding processing are performed, and audio data contained in the main service channel MSC is reproduced.

  Similarly, the RF unit 22 converts a digital broadcast signal received via the antenna 20 into an intermediate frequency signal. The analog-digital converter 24 converts an analog intermediate frequency signal into digital data (intermediate frequency data). The decoder 26 performs demodulation processing and decoding processing on the intermediate frequency data to generate audio data for each service, and extracts the bit rate of the audio data. The RF unit 22, the analog-digital converter 24, and the decoder 26 receive a digital broadcast signal (second digital broadcast signal) broadcast by another broadcast station in a multicarrier system using OFDM as a modulation system. Then, demodulation processing and decoding processing are performed to reproduce audio data contained in the main service channel MSC.

  When one of the first and second digital broadcast signals includes the same service content (program content), the one buffer 30 determines whether or not the second digital broadcast signal has a temporal difference between them. The audio data obtained correspondingly is temporarily stored. For example, audio data for 6 seconds is stored.

  The other buffer 32 temporarily stores audio data obtained corresponding to the second digital broadcast and delays it for a predetermined time. The buffer 32 has a predetermined data capacity. For example, it has a data capacity capable of storing music data with a bit rate of 96 kbit / s for 3 seconds.

  The reception state determination unit 40 determines the reception state of the first and second digital broadcast signals being received. For example, the reception state determination unit 40 detects the electric field strengths of the first and second digital broadcast signals based on the intermediate frequency signals output from the RF units 12 and 22, and based on the detected electric field strengths, The reception state of the broadcast signal is determined. Note that the reception state may be determined based on BER (code error rate), CN ratio (carrier-to-noise ratio), or the like.

  When the first and second digital broadcast signals include the same service content (program content), the delay time determination unit 42 determines a time lag between them. This determination is based on the audio data corresponding to the second digital broadcast signal stored in the buffer 30 (the audio data for the previous 6 seconds) and the audio corresponding to the first digital broadcast signal being received at that time. This is done by comparing the data. In the present embodiment, when the reception state of the first digital broadcast signal deteriorates, the second digital broadcast signal having the same service content is switched without a sense of incongruity (so that the content of output audio data is not interrupted). (Continuous reproduction) is assumed, and the second digital broadcast signal arrives earlier than the first digital broadcast signal by a predetermined time. The continuous reproduction described above is performed only when the predetermined time does not exceed 3 seconds at the maximum and the audio data for the predetermined time at that time can be stored in the buffer 32. In this embodiment, the delay time is limited by setting the maximum value (delay time upper limit value) T0 of the predetermined time to 3 seconds (fixed value) regardless of the data capacity of the buffer 32, but this limit is not provided. May be.

  The switchability determination unit 44 can switch the audio data of a specific service included in the first digital broadcast signal having the same service content to the audio data of the same content included in the second digital broadcast signal. It is determined whether or not. In this determination, if the time lag (predetermined time) determined by the delay time determining unit 42 is within 3 (= T0) seconds or within 3 seconds, the buffer 32 further stores a predetermined amount of audio. This is done by checking whether data can be stored.

  FIG. 3 is a diagram showing the relationship between the bit rate of audio data and the adjustable range of delay time using the buffer 32 (upper limit value of delayable time).

  In this embodiment, since the buffer 32 capable of storing music data with a bit rate of 96 kbit / s for 3 seconds is used, for music data with a bit rate of 96 kbit / s or less, the data for 3 seconds is buffered. The upper limit value of the adjustable range of the delay time is 3 seconds.

  On the other hand, for music data having a bit rate exceeding 96 kbit / s, only a part of the data for 3 seconds can be stored in the entire buffer 32. Specifically, to what extent the data can be stored in the entire buffer 32 is shown in “adjustable range” in FIG. 3 in seconds. For example, when the bit rate is 112 kbit / s, it is 2.50 seconds, when it is 192 kbit / s, it is 1.50 seconds, and when it is 384 kbit / s, it is 0.70 seconds.

  The switchability determination unit 44 refers to the time difference determined by the delay time determination unit 42 as T1 (seconds), and the adjustable range corresponding to the bit rate of the audio data at that time as T2 (seconds, see FIG. 3). When (T1 ≦ T0 (= 3)) and (T1 ≦ T2), it is determined that switching to audio data corresponding to the second digital broadcast signal is possible. Instead of determining that switching is possible in the case of (T1 ≦ T0) and (T1 ≦ T2), it may be determined that switching is possible in the case of (T1 ≦ T2). . In this way, it is possible to determine whether or not switching is possible (delay or not) simply by confirming the magnitude relationship between a plurality of types of times, and the processing required for the determination can be simplified.

  When the switchability determination unit 44 determines that the switching is possible, the output switching setting unit 46 converts the audio data of the first digital broadcast signal corresponding to the same content service to the second digital broadcast signal. The delay time (= T1) necessary for switching to the audio data is set in the buffer 32, and this switching is instructed to the switching unit 50 after the delay time T1 has elapsed.

  In the present embodiment, it is necessary to receive the second digital broadcast signal having the same service content as the first digital broadcast signal being received on the RF unit 12 side on the RF unit 22 side. For example, the same service search unit 48 has the same service identification code SID as the service included in the first digital broadcast signal in parallel with the reception operation of the first digital broadcast signal using the RF unit 12 or the like. Search for other reception frequency (ensemble) services using the configuration on the RF unit 22 side. When a corresponding service is detected, an instruction is sent from the same service search unit 48 to the RF unit 22, and reception of this service is started.

  The switching unit 50 selects and outputs either the audio data input from the decoder 16 or the audio data output from the decoder 26 and input via the buffer 32. For example, the audio data on the decoder 16 side is normally selected, but when switching is instructed from the output switching setting unit 46, the audio data on the buffer 32 side is selected thereafter.

  The output processing unit 52 receives the audio data output from the switching unit 50, and performs switching of audio data to be output, variable control of volume, superimposition processing of other sounds (for example, operation sounds), and the like. . The amplifier 54 amplifies the sound data output from the output processing unit 52 and outputs the amplified sound from the speaker 56. Actually, it is necessary to convert the audio data after various processes in the output processing unit 52 into an analog audio signal. This conversion processing may be performed in the output processing unit 52, but the output processing unit 52 You may make it carry out by providing a digital-analog converter in the back | latter stage.

  The RF unit 12, the analog-digital converter 14 and the decoder 16 are the first receiving means, the RF unit 22, the analog-digital converter 24 and the decoder 26 are the second receiving means, and the delay time judging unit 42 is The buffer 32 corresponds to the delay means, the switchability determination unit 44 corresponds to the delay determination unit, the switching unit 50 corresponds to the switching unit, and the output switching setting unit 46 corresponds to the output switching setting unit.

  The digital broadcast receiver according to the present embodiment has such a configuration. Next, when the reception state of the audio output target service included in the first digital broadcast signal being received deteriorates, the second The operation of switching the audio output target to the service having the same content included in the digital broadcast signal and continuing the audio output so that the content is not interrupted will be described.

  FIG. 4 is a flowchart showing an operation procedure for switching between services having the same contents. The same service search unit 48 determines whether the service included in the first digital broadcast signal is being received using the RF unit 12 or the like (step 100). If not, a negative determination is made and this determination is repeated.

  If the service is being received, an affirmative determination is made in step 100. Next, the same service search unit 48 uses the configuration on the RF unit 22 side for a service of another frequency (ensemble) having the same service identification code SID as the service being received included in the first digital broadcast signal. (Step 102). Next, the same service search unit 48 determines whether or not the corresponding service exists (step 104). If no corresponding service exists, a negative determination is made, and a series of processes related to service switching ends.

  If there is a corresponding service, an affirmative determination is made in step 104. Next, the reception state determination unit 40 determines whether or not the reception state of the first digital broadcast signal has deteriorated (step 106). If the reception state has not deteriorated, a negative determination is made, and the process returns to step 100 to repeat the determination of whether or not the service is being received. Further, when the reception state of the first digital broadcast signal deteriorates, an affirmative determination is made in the determination of step 106.

  Next, the delay time determination unit 42 chronologically shifts the audio data of the service having the same content corresponding to the first and second digital broadcast signals (the first time when the service of the second digital broadcast signal is used as a reference). 1 (delay time of service of digital broadcast signal) T1 is determined (step 108). Further, the switchability determination unit 44 detects the bit rate of the audio data extracted by the decoder 26 (step 110), and outputs the audio data of a specific service included in the first digital broadcast signal having the same service content. It is determined whether or not it is possible to switch to service audio data included in the second digital broadcast signal (step 112). As described above, specifically, this determination is performed by examining whether (T1 ≦ T0) and (T1 ≦ T2) are satisfied.

  If switching is possible, an affirmative determination is made in step 112. Next, the output switching setting unit 46 buffers the delay time (= T1) necessary for switching the audio data of the first digital broadcast signal corresponding to the service of the same content to the audio data of the second digital broadcast signal. 32 is set (step 114). Further, the output switching setting unit 46 determines whether or not the time corresponding to the delay time T1 has elapsed (step 116). If not, a negative determination is made and this determination is repeated. Here, the reason for waiting for the elapse of the delay time T1 is to avoid the partial overlap of the output audio contents when the audio data is switched before the elapse of time.

  When the delay time T1 has elapsed, an affirmative determination is made in the determination of step 116. Next, the output switching setting unit 46 instructs the switching unit 50 to perform switching (step 118), and the switching unit 50 selects the output target from the audio data output from the decoder 16 through the buffer 32 in accordance with this instruction. Switching to output audio data (step 120).

  When switching is not possible (when either (T1> T0) or (T1> T2) is satisfied), a negative determination is made in the determination of step 112, and then the routine immediately proceeds to step 120 to switch the audio data. Is implemented. In practice, it is desirable to perform mute processing (silence processing) for a predetermined period of time because switching immediately makes it clear that the audio content is not continuous and emphasizes the sense of discomfort at discontinuous points. . For example, the mute process is performed by the output processing unit 52.

  FIG. 5 is an explanatory diagram showing the effect of switching music data in the present embodiment. When continuous playback is possible (when an affirmative determination is made in the determination of step 112), after the delay time determination, switching is performed after the time of delay time T1 (for example, 3 seconds) has elapsed. No continuous voice output can be continued (FIG. 5A).

  In addition, when continuous playback is impossible (when a negative determination is made in the determination of step 112), the determination of whether or not switching is possible is made immediately after the delay time determination (determining whether or not switching is possible, so there is almost no delay. ) Switching with a mute process is performed (FIG. 5B).

  On the other hand, conventionally, when continuous playback is not possible, after determining the delay time, after repeating the time adjustment corresponding to the maximum delay time multiple times (for example, 3 seconds twice) and giving up switching for continuous playback Then, switching with mute processing is performed (FIG. 5C). For this reason, conventionally, it takes a long time to output the sound after switching.

  As described above, in the digital broadcast receiver according to the present embodiment, when switching from the audio output corresponding to the first digital broadcast signal to the audio output corresponding to the second digital broadcast signal having the same content, the determination as to whether or not the audio output is possible. Since this is performed based on the data bit rate and the data capacity of the buffer 32, the time required for this determination can be shortened compared with the case where the time adjustment for performing the delay is actually performed to confirm the possibility. This can shorten the time until the voice output after switching.

  In particular, when it is not possible to switch the audio output content to be continuous, it is possible to immediately perform switching that allows the audio output content to be discontinuous. It is possible to greatly shorten the time. Further, in this case, by combining mute processing (silence processing), it is possible to reduce the uncomfortable feeling felt by the user due to the discontinuity of the content of the audio output.

  In addition, this invention is not limited to the said embodiment, A various deformation | transformation implementation is possible within the range of the summary of this invention. For example, in the above-described embodiment, the present invention is applied to a digital broadcast receiver as a DAB receiver. However, the present invention can be applied to other digital broadcast receivers.

  As described above, according to the present invention, when switching from the audio output corresponding to the first digital broadcast signal to the audio output corresponding to the second digital broadcast signal having the same content, whether or not it is possible is determined by the bit of the audio data. Since it is based on the rate and the data capacity of the delay means, the time required for this determination can be shortened compared with the case where the time adjustment for performing the delay is actually performed and whether it is possible or not is confirmed. The time until the subsequent voice output can be shortened.

10, 20 Antenna 12, 22 RF section 14, 24 Analog-digital converter (A / D)
16, 26 Decoder 30, 32 Buffer 40 Reception state determination unit 42 Delay time determination unit 44 Switchability determination unit 46 Output switching setting unit 48 Same service search unit 50 Switching unit (SW)
52 Output Processing Unit 54 Amplifier 56 Speaker

Claims (7)

First receiving means for receiving a first digital broadcast signal and outputting first audio data;
Second receiving means for receiving a second digital broadcast signal corresponding to audio data of the same content and outputting the second audio data;
Delay time determination that compares the audio data of the same content output from the first and second receiving means and determines a time lag of the first audio data with respect to the second audio data as a delay time Means,
Delay means having a predetermined data capacity, and delaying the second audio data within a range equal to or less than the upper limit value with a time corresponding to the data capacity as an upper limit value;
Whether or not it is possible to delay the output of the second audio data using the delay means by the delay time determined by the delay time determination means, and the bit rate of the second audio data, A delay propriety judging means for judging based on the data capacity of the delay means;
A digital broadcast receiver comprising: In claim 1,
Switching means for switching voice data from the first receiving means to voice data delayed by the delay means;
Output switching for instructing switching to the switching means after the lapse of the delay time determined by the delay time determining means when the delay possibility determining means determines that delay is possible Setting means;
A digital broadcast receiver further comprising: In claim 2,
The digital broadcast receiver characterized in that the output switching setting means immediately instructs the switching means to switch when the delay availability determining means determines that the delay cannot be made. In claim 3,
A digital broadcast receiver characterized in that silence processing is performed on audio data immediately after switching the switching means when it is determined by the delay availability determining means that delay cannot be performed. In any one of Claims 1-4,
When the delay time determined by the delay time determination means is T1, and the upper limit value of the time that can be delayed by the delay means based on the bit rate of the second audio data and the data capacity of the delay means is T2. In addition,
The digital broadcast receiver according to claim 1, wherein the delay availability determination unit determines that the delay is possible when the relationship of T1 ≦ T2 is satisfied. In claim 5,
When the delay time upper limit value as a fixed value set regardless of the data capacity of the delay means is T0,
The digital broadcast receiver according to claim 1, wherein the delay propriety determining means determines that delay is possible when the relationship of T1 ≦ T0 and T1 ≦ T2 is satisfied. In any one of Claims 1-6,
The digital broadcast receiver according to claim 1, wherein the first and second digital broadcast signals are digital broadcast signals according to a DAB broadcast standard.

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