BROADCAST RECEIVING APPARATUS AND METHOD FOR CONTROLLING OUTPUT OF THE SAME

Abstract

 Broadcast receiving apparatus (10, 10') including a delay-time calculating unit (107) and a delay processing unit (109, 109'). The delay-time calculating unit (107) calculates the delay time of an IP broadcast relative to a DAB broadcast. The delay processing unit (109, 109') synchronizes output timing of audio data in the DAB broadcast with output timing of audio data in the IP broadcast by performing delay processing on the audio data in the DAB broadcast according to the calculated delay time. The delay processing unit (109, 109') stretches the output time of data containing no sound using a delay rate higher than a delay rate for data containing sound to increase the proportion of the output time of the data containing no sound in the whole of output time of the audio data stretched and to decrease the proportion of the output time of the data containing sound.

Description

[0001] The present invention relates to a broadcast receiving apparatus and a method for controlling the output of the broadcast receiving apparatus, and in particular, it relates to a broadcast receiving apparatus configured to switch between a broadcast based on a first standard and a broadcast based on a second standard delayed from the broadcast of the first standard and to output a selected broadcast, as well as a method for controlling the same.

[0002] Known broadcast receiving apparatuses in the related art are configured to receive two broadcasts based on different standards but having the same content (for example, a digital audio broadcast (DAB) and an Internet protocol (IP) broadcast) and to output selected one of the two broadcast. This allows, for example, when the reception environment of one of the broadcasts deteriorates, the broadcast to be switched to the other broadcast for output, thus allowing the user to continue listening to the same content.

[0003] However, there can be a time difference between the two broadcasts received by the broadcast receiving apparatus. For example, in a broadcast receiving apparatus configured to switch between a DAB broadcast and an IP broadcast and to output a selected broadcast, the IP broadcast is transmitted from a broadcast station via a provider and an Internet server, for example. It is known that this can cause a time difference between the DAB broadcast and the IP broadcast received by the broadcast receiving apparatus, that is, reception of the IP broadcast is delayed relative to reception of the DAB broadcast.

[0004] To cope with this, a technique for seamlessly switching between the two broadcasts by eliminating the time difference between them to synchronize the output timings has been proposed.

[0005] For example, JP 2008-227599 A discloses a technique for an IP broadcast transmission system with a dual configuration including a 1-system IP transmission server and a 2-system IP transmission server. The technique involves periodically adding time stamps to individual transport streams (TSs) of the 1-system and the 2-system, detecting the difference value between a program clock reference (PCR) code in each TS and the time stamp, and performing synchronization processing on the TS signals on the basis of the difference values detected in the 1-system and the 2-system. This allows IP packets to be synchronously input to a switch from the 1-system IP transmission server and the 2-system IP transmission server, allowing smooth switching of images.

[0006] For conventional broadcast receiving apparatuses configured to switch between a DAB broadcast and an IP broadcast and output a selected broadcast, there is a known method for synchronizing the output timing of audio data in the DAB broadcast with the output timing of audio data in the IP broadcast by obtaining the delay time of the IP broadcast relative to the DAB broadcast and by performing delay processing (time stretching) on the audio data in the DAB broadcast according to the delay time.

[0007] Fig. 9 is a diagram illustrating an example of process timing of a conventional broadcast receiving apparatus. This is an example in which audio data with the same content is broadcasted in the form of data stream "1", "2", "3", "4", ... in both of the DAB broadcast and the IP broadcast. Fig. 9 schematically illustrates an example in which one frame of audio data is audio data in a predetermined time (for example, one second).

[0008] As illustrated in Fig. 9, the IP broadcast is received later than the DAB broadcast because the IP broadcast is transmitted to the broadcast receiving apparatus from a broadcast station via a provider, an Internet server, and so on, although the audio data in the DAB broadcast and the audio data in the IP broadcast have the same content. In the example illustrated in Fig. 9, the IP broadcast is received with a delay of four frames of audio data relative to the DAB broadcast.

[0009] Therefore, in the example of Fig. 9, the output timing of the audio data in the DAB broadcast is synchronized with the output timing of the audio data in the IP broadcast by performing delay processing on the audio data in the DAB broadcast so as to allow seamlessly switching from the audio output of the DAB broadcast to the audio output of the IP broadcast.

[0010] Specifically, when the power sources is turned ON (timing t1), the broadcast receiving apparatus starts reception of audio data in the DAB broadcast and the IP broadcast. The broadcast receiving apparatus calculates the delay time of the IP broadcast relative to the DAB broadcast (timing t2). At that timing, the broadcast receiving apparatus performs delay processing on the output audio data in the DAB broadcast according to the calculated delay time.

[0011] Specifically, the broadcast receiving apparatus performs time stretching on the audio data in the DAB broadcast by a necessary number of frames so as to resolve the calculated delay time of the IP broadcast (timing t2 to t3). The time stretching is the process of stretching the output time of audio data by decreasing the frequency of output audio data.

[0012] The delay processing allows the broadcast receiving apparatus to resolve the delay time of the IP broadcast relative to the DAB broadcast to produce a state in which the output timing of the DAB broadcast and the output timing of the IP broadcast are synchronized with each other (the state after timing t3), thus allowing seamless switching from the DAB broadcast to the IP broadcast.

[0013] However, the conventional broadcast receiving apparatus delays the audio data in the DAB broadcast using a fixed delay rate (the ratio of an output time before delay processing to an output time after the delay processing). This produces such a problem that the user has to continue to listen to audio modulated by the delay processing for a long time while the broadcast receiving apparatus is performing delay processing.

[0014] In the example of Fig. 9, four frames of audio data "7" to "10" in the DAB broadcast are delayed to synchronize the output timing of the DAB broadcast with the output timing of the IP broadcast. In the example of Fig. 9, the output times of all of the audio data "7" to "10" are stretched using a fixed delay rate (in the example of Fig. 9, 200%). In this case, the user has to continue to listen to the audio modulated by the delay processing for a long time during which the audio data "7" to "10" is output (corresponding to an output time of eight frames of audio data that is not subjected to time stretching).

[0015] Although the example of Fig. 9 uses a delay rate of 200% for illustrative purpose, an actual delay rate is about 110%, and the output time of modulated audio will be longer than that in the above example.

[0016] An object of the invention is to reduce the time during which audio modulated by delay processing is output in a broadcast receiving apparatus configured to synchronize two broadcasts using delay processing.

[0017] The invention relates to a broadcast receiving apparatus and a method according to the independent claims. Embodiments are disclosed in the dependent claims. A broadcast receiving apparatus according to an aspect of the present invention is configured to synchronize the output timing of audio data in a first standard broadcast with the output timing of audio data in a second standard broadcast by calculating the delay time of the second standard broadcast relative to the first standard broadcast and by performing delay processing on the audio data in the first standard broadcast according to the calculated delay time. In the delay processing on the audio data in the first standard broadcast, the broadcast receiving apparatus stretches the output time of data containing no sound using a delay rate higher than a delay rate for data containing sound.

[0018] According to the aspect of the present invention, the proportion of the output time of data containing no sound of the whole of the output time of audio data stretched by delay processing on audio data in the first standard broadcast is increased, and the proportion of output time of data containing sound is decreased. Thus, the output time of sound modulated by delay processing can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] 

Fig. 1 is a block diagram illustrating an example of the functional configuration of a broadcast receiving apparatus according to a first embodiment of the present invention;

Fig. 2 is a flowchart illustrating an example (a first example) of processing performed by the broadcast receiving apparatus according to the first embodiment of the present invention;

Fig. 3A is a diagram illustrating an example (a first example) of process timing of the broadcast receiving apparatus according to the first embodiment of the present invention;

Fig. 3B is a diagram illustrating an example (a first example) of process timing of the broadcast receiving apparatus according to the first embodiment of the present invention;

Fig. 4 is a flowchart illustrating an example (a second example) of processing performed by the broadcast receiving apparatus according to the first embodiment of the present invention;

Fig. 5A is a diagram illustrating an example (a second example) of process timing of the broadcast receiving apparatus according to the first embodiment of the present invention;

Fig. 5B is a diagram illustrating an example (a second example) of process timing of the broadcast receiving apparatus according to the first embodiment of the present invention;

Fig. 6 is a block diagram illustrating an example of the functional configuration of a broadcast receiving apparatus according to a second embodiment of the present invention;

Fig. 7 is a flowchart illustrating an example of processing performed by the broadcast receiving apparatus according to the second embodiment of the present invention;

Fig. 8A is a diagram illustrating an example of process timing of the broadcast receiving apparatus according to the second embodiment of the present invention;

Fig. 8B is a diagram illustrating an example of process timing of the broadcast receiving apparatus according to the second embodiment of the present invention; and

Fig. 9 is a diagram illustrating an example of process timing of a conventional broadcast receiving apparatus.

[0020] A first embodiment of the present invention will be described hereinbelow with reference to Figs. 1 to Figs. 5A and 5B. Fig. 1 is a block diagram illustrating an example of the functional configuration of a broadcast receiving apparatus 10 according to the first embodiment of the present invention. The broadcast receiving apparatus 10 illustrated in Fig. 1 is an apparatus capable of receiving a DAB broadcast (an example of a broadcast based on a first standard) and an IP broadcast (an example of a broadcast based on a second standard), switching between audio data in the DAB broadcast (an example of the first standard broadcast) and audio data in the IP broadcast (an example of the second standard broadcast), and outputting selected audio data to a speaker 12.

[0021] As illustrated in Fig. 1, the broadcast receiving apparatus 10 includes a first receiver 101, a first demodulator 102, a DAB buffer 103, a second receiver 104, a second demodulator 105, an IP buffer 106, a delay-time calculating unit 107, a silent-data detection unit 108, a delay processing unit 109, and an output control unit 110.

[0022] The above functional blocks 101 to 110 can be any of hardware, digital signal processors (DSPs), and software. With software, the functional blocks 101 to 110 actually include a CPU, a RAM, a ROM, and so on of a computer and are implemented by programs stored in a storage medium in the RAM, ROM, a hard disk, or a semiconductor memory.

[0023] The first receiver 101 receives broadcast waves of the DAB broadcast. The first demodulator 102 demodulates the broadcast waves of the DAB broadcast received by the first receiver 101. The DAB buffer 103 stores audio data in the DAB broadcast received by the first receiver 101 (the DAB broadcast demodulated by the first demodulator 102).

[0024] The second receiver 104 receives communication data in the IP broadcast. The second demodulator 105 demodulated the communication data in the IP broadcast received by the second receiver 104. The IP buffer 106 stores audio data in the IP broadcast received by the second receiver 104 (the IP broadcast demodulated by the second demodulator 105).

[0025] The IP broadcast received by the second receiver 104 has the same content as the content of the DAB broadcast received by the first receiver 101. The IP broadcast is however received by the second receiver 104 later than the DAB broadcast received by the first receiver 101. This is because the first receiver 101 directly receives the broadcast waves of the DAB broadcast, whereas the second receiver 104 receives the communication data in the IP broadcast transmitted from the broadcast station via a provider and an Internet server.

[0026] The output control unit 110 switches between the audio data in the DAB broadcast received by the first receiver 101 (the DAB broadcast demodulated by the first demodulator 102) and the audio data in the IP broadcast received by the second receiver 104 (the IP broadcast demodulated by the second demodulator 105) and outputs selected audio data. For example, when the intensity of the received signal of the DAB broadcast is higher than a predetermined threshold value, the output control unit 110 switches over to the DAB broadcast and outputs the audio data. In contrast, when the intensity of the received signal of the DAB broadcast is lower than the predetermined threshold value, the output control unit 110 switches over to the IP broadcast and outputs the audio data. In other words, the output control unit 110 preferentially outputs the DAB broadcast of higher quality than that of the IP broadcast. The audio data output from the output control unit 110 is amplified by an amplifier 11 and is output from the speaker 12.

[0027] The delay-time calculating unit 107 calculates the delay time of the IP broadcast received by the second receiver 104 relative to the DAB broadcast received by the first receiver 101. For example, the delay-time calculating unit 107 compares the audio data in the DAB broadcast stored in the DAB buffer 103 and the audio data in the IP broadcast stored in the IP buffer 106 to specify the same data as the audio data in the IP broadcast stored in the IP buffer 106 from the audio data in the DAB broadcast stored in the DAB buffer 103. The delay-time calculating unit 107 then calculates the delay time of the IP broadcast relative to the DAB broadcast on the basis of the timing of reception of the audio data in the IP broadcast stored in the IP buffer 106 and the timing of reception of the specified same data in the DAB buffer 103.

[0028] The delay-time calculating unit 107 calculates remaining delay time every time the data processed by the delay processing unit 109 switches from audio data including no sound (hereinafter referred to as "silent data ") to audio data including sound (hereinafter referred to as "sound data") and switches from sound data to silent data. For example, when the delay processing unit 109 performs delay processing on silent data, and then the target silent data switches over to sound data, the delay-time calculating unit 107 calculates a remaining delay time after the silent data is subjected to the delay processing by subtracting a delay time resolved by the delay processing on the silent data from the first calculated delay time.

[0029] Thereafter, when the delay processing unit 109 performs delay processing on sound data, and then the delay processing target sound data switches over to silent data, the delay-time calculating unit 107 calculates a remaining delay time after the sound data is subjected to the delay processing by subtracting a delay time resolved by the delay processing on the sound data from the remaining delay time calculated after the delay processing on the silent data.

[0030] The silent-data detection unit 108 detects silent data from the audio data in the DAB broadcast. The silent-data detection unit 108 also detects the length of the silent data. For example, the silent-data detection unit 108 detects, as silent data, a mute, zero data, and data with a bit error rate (BER) higher than a predetermined threshold value. In a case where an FM broadcast is applied as the first standard broadcast, the silent-data detection unit 108 detects, as silent data, data with a maximum instantaneous frequency deviation smaller than a predetermined threshold value.

[0031] The delay processing unit 109 performs delay processing (time stretching) on the audio data in the DAB broadcast according to the delay time calculated by the delay-time calculating unit 107. Thus, the delay processing unit 109 synchronizes the output timing of the audio data in the DAB broadcast output from the output control unit 110 with the output timing of the audio data in the IP broadcast output from the output control unit 110.

[0032] In the delay processing on the audio data in the DAB broadcast, the delay processing unit 109 stretches the duration of the silent data detected by the silent-data detection unit 108 using a delay rate higher than a delay rate for the sound data. In particular, in the first embodiment, the delay processing unit 109 stretches the duration of the silent data within a range in which the output time of the silent data after time stretching does not exceed a predetermined threshold value th.

[0033] In one example, the delay processing unit 109 stretches the output time of the silent data using a variable delay rate according to the length of the silent data and the predetermined threshold value th so that the stretched silent data has a predetermined length. Specifically, the delay processing unit 109 stretches the output time of the silent data using a variable delay rate so that the stretched silent data has a length during which the remaining delay time can be resolved. If the duration of the stretched silent data will be longer than the predetermined threshold value th, the delay processing unit 109 stretches the output time of the silent data using a variable delay rate so that the stretched silent data has the same length as the predetermined threshold value th.

[0034] In another example, the delay processing unit 109 stretches the output time of the silent data every predetermined length using a fixed delay rate within the predetermined threshold value th. When the continuous output time of the silent data reaches the predetermined threshold value th by stretching the silent data, the delay processing unit 109 detects sound data subsequent to the silent data and stretches the output time of the detected sound data.

Example of Processing Performed by Broadcast Receiving Apparatus 10 (First Example)

[0035] Fig. 2 is a flowchart illustrating an example (a first example) of processing performed by the broadcast receiving apparatus 10 according to the first embodiment of the present invention. The processing illustrated in Fig. 2 is executed, for example, when the power source of the broadcast receiving apparatus 10 is turned ON. In the first example, the delay processing unit 109 stretches the output time of silent data using a variable delay rate.

[0036] When the power source of the broadcast receiving apparatus 10 is turned ON, reception of the DAB broadcast with the first receiver 101 and demodulation with the first demodulator 102 and reception of the IP broadcast with the second receiver 104 and demodulation with the second demodulator 105 are performed in parallel, although not illustrated in Fig. 2.

[0037] First, the DAB buffer 103 stores the audio data in the DAB broadcast received by the first receiver 101 (step S202). The IP buffer 106 stores the audio data in the IP broadcast received by the second receiver 104 (step S204). The delay-time calculating unit 107 calculates the delay time of the IP broadcast relative to the DAB broadcast on the basis of the audio data stored in the DAB buffer 103 and the audio data stored in the IP buffer 106 (step S206). The delay processing unit 109 starts delay processing on the audio data in the DAB broadcast according to the delay time calculated at step S206 (step S208).

[0038] In the delay processing, first, the silent-data detection unit 108 extracts data with a predetermined length from the delay processing target audio data (step S210). The silent-data detection unit 108 determines whether the data with the predetermined length extracted at step S210 is silent data (step S212). If the silent-data detection unit 108 determines that the predetermined length of data is not silent data (step S212: No), the delay processing unit 109 stretches the predetermined length of data using a fixed delay rate for sound data (step S226).

[0039] The delay processing unit 109 determines whether the remaining delay time has been resolved by the time stretching on the sound data at step S226 (for sound data, the delay time calculated at step S206 directly after the start of time stretching) (step S228). If the delay processing unit 109 determines that the remaining delay time has been resolved (step S228: Yes), the delay processing unit 109 terminates the delay processing on the DAB broadcast (step S230), and the broadcast receiving apparatus 10 terminates the series of processing illustrated in Fig. 2.

[0040] In contrast, if the delay processing unit 109 determines that the remaining delay time has not been resolved (step S228: No), the broadcast receiving apparatus 10 executes the processing from step S210 onward.

[0041] If at step S212 the silent-data detection unit 108 determines that the predetermined length of data is silent data (step S212: Yes), the delay-time calculating unit 107 calculates a remaining delay time by subtracting a delay time resolved by the delay processing performed by the delay processing unit 109 from a delay time calculated before the delay processing performed by the delay processing unit 109 (step S214). The silent-data detection unit 108 specifies the length of the silent data (step S216). The delay processing unit 109 determines whether the output time of the stretched silent data will be longer than the threshold value th if the silent data is stretched until the remaining delay time (for silent data, a delay time directly after the start of time stretching calculated by the delay-time calculating unit 107 at step S206) is resolved (step S218).

[0042] If the delay processing unit 109 determines that the output time of the stretched silent data will be longer than the threshold value th (step S218: Yes), the delay processing unit 109 stretches the silent data using a delay rate at which the output time of the silent data is equal to the threshold value th (step S222). After completion of the time stretching on the silent data, the delay-time calculating unit 107 calculates a remaining delay time by subtracting a delay time resolved by the time stretching on the silent data from a delay time calculated before the time stretching on the silent data (step S224). Thereafter, the delay processing unit 109 stretches the duration of sound data subsequent to the silent data using the fixed delay rate for sound data (step S226). The broadcast receiving apparatus 10 then moves to the determination process at step S228, described above.

[0043] If the delay processing unit 109 determines that the output time of the silent data after the time stretching will not be longer than the threshold value th (step S218: No), the delay processing unit 109 stretches the duration of the silent data using a delay rate at which the output time of the silent data will be an output time during which the remaining delay time can be resolved (step S220). Upon completion of the time stretching on the silent data, the delay processing unit 109 terminates the delay processing on the DAB broadcast (step S230), and the broadcast receiving apparatus 10 terminates the series of processing illustrated in Fig. 2.

Examples of Process Timing (First Examples)

[0044] Figs. 3A and 3B are diagrams illustrating examples (first examples) of process timing of the broadcast receiving apparatus 10 according to the first embodiment of the present invention. Fig. 3A illustrates an example in which silent data of one frame of audio data is included at the head of delay processing target data. Fig. 3B illustrates an example in which silent data of two frames of audio data is included at the head of delay processing target data. In the examples, audio data with the same contents is broadcasted in the form of data stream "1", "2", "3", "4", ... in both of the DAB broadcast and the IP broadcast. The audio data is schematically illustrated on the assumption that one frame of audio data is audio data in a predetermined time (for example, one second).

[0045] As illustrated in Figs. 3A and 3B, the IP broadcast is received later than the DAB broadcast because the IP broadcast is transmitted from a broadcast station to the broadcast receiving apparatus 10 via a provider, an Internet server, and so on, although the audio data in the DAB broadcast and the audio data in the IP broadcast have the same content. In the examples illustrated in Figs. 3A and 3B, the IP broadcast is received with a delay of four frames of audio data relative to the DAB broadcast.

[0046] Therefore, in the examples illustrated in Figs. 3A and 3B, the output timing of the audio data in the DAB broadcast is synchronized with the output timing of the audio data in the IP broadcast by performing delay processing on the audio data in the DAB broadcast so as to allow seamless switching from the audio output of the DAB broadcast to the audio output of the IP broadcast.

[0047] Specifically, when the power source of the broadcast receiving apparatus 10 is turned ON (timing t1), the first receiver 101 starts reception of the DAB broadcast, and the second receiver 104 starts reception of the IP broadcast. The delay-time calculating unit 107 calculates the delay time of the IP broadcast relative to the DAB broadcast (timing t2). At that timing, the delay processing unit 109 performs delay processing on the output audio data in the DAB broadcast according to the calculated delay time.

[0048] Specifically, the delay processing unit 109 stretches the duration of the audio data in the DAB broadcast by a necessary number of frames so as to resolve the calculated delay time of the IP broadcast (timing t2 to t3).

[0049] This delay processing allows the delay processing unit 109 to resolve the delay time of the IP broadcast relative to the DAB broadcast to produce a state in which the output timing of the DAB broadcast and the output timing of the IP broadcast are synchronized with each other (the state after timing t3). This allows the output control unit 110 to seamlessly switch over from the DAB broadcast to the IP broadcast.

[0050] Since the lengths of the silent data at the head of the delay processing target data in Figs. 3A and 3B differ, different delay rates are applied to the silent data. In Figs. 3A and 3B, the silent data is expressed as "silent", and the sound data is expressed as "sound".

[0051] In the example illustrated in Fig. 3A, at the delay processing start timing (timing t2), the audio data at the head of the DAB broadcast is silent data "7", and the next audio data is sound data "8". The remaining delay time at that time is of four frames of audio data. The threshold value th is set to four frames of audio data.

[0052] In this case, the delay processing unit 109 determines whether the output time of the silent data "7" will exceed the threshold value th if the output time of silent data "7" is stretched to an output time during which the remaining delay time can be resolved. In the example illustrated in Fig. 3A, the remaining delay time can be resolved by stretching the output time of the silent data "7" to five frames of audio data 5, but the stretched data will exceed the threshold value th (corresponding to four frames of audio data). Therefore, the delay processing unit 109 stretches the output time of the silent data "7" to the threshold value th.

[0053] This time stretching on the silent data "7" resolves a delay time corresponding to three frames of audio data. This causes the remaining delay time to be one frame of audio data. Thereafter, the delay processing unit 109 stretches the duration of the next sound data "8" using a fixed delay rate (200%) for sound data. This resolves the remaining delay time, synchronizing the output timing of the DAB broadcast with the output timing of the IP broadcast (timing t3).

[0054] In contrast, in the example illustrated in Fig. 3B, at the delay processing start timing (timing t2), the audio data at the head of the DAB broadcast is silent data "7", followed by silent data "8", sound data "9", and sound data "10". The remaining delay time at that time is of four frames of audio data.

[0055] In this case, the delay processing unit 109 determines whether the output time of audio data α, which is the sum of the silent data "7" and the silent data "8", will exceed the threshold value th if the output time of the audio data α is stretched to an output time during which the remaining delay time can be resolved. In the example illustrated in Fig. 3B, the remaining delay time can be resolved by stretching the output time of the audio data α to six frames of audio data, but the stretched data will exceed the threshold value th (four frames of audio data). Therefore, the delay processing unit 109 stretches the output time of the audio data α to the threshold value th.

[0056] This time stretching on the audio data α resolves a delay time corresponding to two frames of audio data 2. This causes the remaining delay time to be two frames of audio data. Thereafter, the delay processing unit 109 stretches the duration of the next sound data "9" using a fixed delay rate (200%) for sound data. Next, the delay processing unit 109 stretches the duration of the sound data "10" using the fixed delay rate (200%) for sound data. This resolves the remaining delay time, thus synchronizing the output timing of the DAB broadcast with the output timing of the IP broadcast (timing t3).

[0057] In the case of Fig. 3B, the length of the silent data after the time stretching is the same as the length of the related art illustrated in Fig. 9, but using a threshold value greater than four frames of audio data allows the length of the silent data after the time stretching to be longer than that in the related art illustrated in Fig. 9. Example of Processing Performed by Broadcast Receiving Apparatus 10 (Second Example)

[0058] Fig. 4 is a flowchart illustrating an example (a second example) of processing performed by the broadcast receiving apparatus 10 according to the first embodiment of the present invention. The processing illustrated in Fig. 4 is executed, for example, when the power source of the broadcast receiving apparatus 10 is turned ON. In the second example, the delay processing unit 109 stretches the output time of silent data using a fixed delay rate.

[0059] When the power source of the broadcast receiving apparatus 10 is turned ON, reception of the DAB broadcast with the first receiver 101 and demodulation with the first demodulator 102 and reception of the IP broadcast with the second receiver 104 and demodulation with the second demodulator 105 are performed in parallel, although not illustrated in Fig. 4.

[0060] First, the DAB buffer 103 stores the audio data in the DAB broadcast received by the first receiver 101 (step S402). The IP buffer 106 stores the audio data in the IP broadcast received by the second receiver 104 (step S404). The delay-time calculating unit 107 calculates the delay time of the IP broadcast relative to the DAB broadcast on the basis of the audio data stored in the DAB buffer 103 and the audio data stored in the IP buffer 106 (step S406). The delay processing unit 109 starts delay processing on the audio data in the DAB broadcast according to the delay time calculated at step S406 (step S408).

[0061] In the delay processing, first, the silent-data detection unit 108 extracts data with a predetermined length from the delay processing target audio data (step S410). The silent-data detection unit 108 determines whether the data with the predetermined length extracted at step S410 is silent data (step S412). If the silent-data detection unit 108 determines that the predetermined length of data is not silent data (step S412: No), the delay processing unit 109 stretches the predetermined length of data using a fixed delay rate for sound data (step S414).

[0062] The delay processing unit 109 determines whether the remaining delay time has been resolved by the time stretching on the sound data at step S414 (for sound data, the delay time calculated at step S406 directly after the start of time stretching) (step S416). If the delay processing unit 109 determines that the remaining delay time has been resolved (step S416: Yes), the delay processing unit 109 terminates the delay processing on the DAB broadcast (step S430), and the broadcast receiving apparatus 10 terminates the series of processing illustrated in Fig. 4.

[0063] In contrast, if the delay processing unit 109 determines that the remaining delay time has not been resolved (step S416: No), the broadcast receiving apparatus 10 executes the processing from step S410 onward.

[0064] If at step S412 the silent-data detection unit 108 determines that the predetermined length of data is silent data (step S412: Yes), the delay-time calculating unit 107 calculates a remaining delay time by subtracting a delay time resolved by the delay processing performed by the delay processing unit 109 from a delay time calculated before the delay processing performed by the delay processing unit 109 (step S418). The delay processing unit 109 stretches the duration of the predetermined length of data using a fixed delay rate for silent data (step S420).

[0065] The delay processing unit 109 determines whether the remaining delay time has been resolved by the time stretching on the silent data at step S420 (for silent data, the delay time calculated at step S406 directly after the start of time stretching) (step S422). If the delay processing unit 109 determines that the remaining delay time has been resolved (step S422: Yes), the delay processing unit 109 terminates the delay processing on the DAB broadcast (step S430), and the broadcast receiving apparatus 10 terminates the series of processing illustrated in Fig. 4.

[0066] In contrast, if the delay processing unit 109 determines that the remaining delay time has not been resolved (step S422: No), the delay processing unit 109 determines whether the continuous output time of the silent data has exceeded the threshold value th (step 424). If the delay processing unit 109 determines that the continuous output time of the silent data has not exceeded the threshold value th (step 424: No), the broadcast receiving apparatus 10 executes the processes of step S410 and the subsequent steps again.

[0067] In contrast, if the delay processing unit 109 determines that the continuous output time of the silent data has exceeded the threshold value th (step 424: Yes), the delay-time calculating unit 107 calculates a remaining delay time by subtracting a delay time resolved by the time stretching at step S420 from a delay time calculated before the delay processing performed by the delay processing unit 109 (step S426).

[0068] Thereafter, the silent-data detection unit 108 detects sound data as the next delay processing target from the audio data following the silent data (step 428). The broadcast receiving apparatus 10 then executes the processes at step S410 and the subsequent steps again. Examples of Process Timing (Second Examples)

[0069] Figs. 5A and 5B are diagrams illustrating examples (second examples) of process timing of the broadcast receiving apparatus 10 according to the first embodiment of the present invention. Fig. 5A illustrates an example in which silent data of two frames of audio data is included at the head of delay processing target data. Fig. 5B illustrates an example in which silent data of three frames of audio data is included at the head of delay processing target data. In Figs. 5A and 5B, the content and reception timing of the audio data in the IP broadcast and the DAB broadcast are the same as those in the first embodiment (Figs. 3A and 3B), and the description thereof will be omitted. In the examples illustrated in Figs. 5A and 5B, the IP broadcast is received with a delay of six frames of audio data relative to the DAB broadcast. The threshold value th is set to six frames of audio data.

[0070] In the examples illustrated in Figs. 5A and 5B, time stretching is performed for each frame of audio data with a predetermined length. A fixed delay rate (300%) is applied to the silent data. A fixed delay rate (200%) is applied to the sound data. In Figs. 5A and 5B, the silent data is expressed as "silent", and the sound data is expressed as "sound".

[0071] In the examples illustrated in Figs. 5A and 5B, audio data at the head of the DAB broadcast at the delay processing start timing (timing t2) is silent data "9". The remaining delay time at that time is of six frames of audio data 6.

[0072] In the case of Fig. 5A, first, the delay processing unit 109 stretches the duration of the silent data "9" using the fixed delay rate (300%). At this stage, the remaining delay time (corresponding to six frames of audio data) has not been resolved, and the continuous output time of the silent data has not exceeded the threshold value th (corresponding to six frames of audio data). Therefore, the delay processing unit 109 stretches the duration of the next silent data "10" using the fixed delay rate (300%). At this stage, the remaining delay time has not yet been resolved, but the continuous output time of the silent data has reached the threshold value th. A delay time resolved by the above time stretching corresponds to four frames of audio data. Thus, the remaining delay time is of two frames of audio data.

[0073] Next, the delay processing unit 109 stretches the duration of sound data "11" using the fixed delay rate (200%). At this stage, the remaining delay time (corresponding to two frames of audio data) has not yet been resolved. Therefore, the delay processing unit 109 stretches the duration of the following sound data "12" using the fixed delay rate (200%). This delay processing resolves the remaining delay time, thus synchronizing the output timing of the DAB broadcast with the output timing of the IP broadcast (timing t3).

[0074] In contrast, in the example illustrated in Fig. 5B, the delay processing unit 109 first stretches the duration of the silent data "9" using the fixed delay rate (300%). At this stage, the remaining delay time (corresponding to six frames of audio data) has not been resolved, and the continuous output time of the silent data has not yet exceeded the threshold value th (corresponding to six frames of audio data). Thus, the delay processing unit 109 stretches the duration of the following silent data "10" using the fixed delay rate (300%). At this stage, the remaining delay time has not yet been resolved, but the continuous output time of the silent data has reached the threshold value th. A delay time resolved by the above time stretching is of four frames of audio data. Therefore, the remaining delay time is of two frames of audio data.

[0075] If the next silent data "11" is stretched using the fixed delay rate (300%), the continuous output time of the silent data exceeds the threshold value th. Therefore, the delay processing unit 109 does not output the silent data "11" and stretches the duration of the first sound data "12" following the silent data "11" using the fixed delay rate (200%). At this stage, the remaining delay time (corresponding to two frames of audio data) has not yet been resolved. Therefore, the delay processing unit 109 subsequently stretches the duration of the next sound data "13" using the fixed delay rate (200%). At this stage, the remaining delay time has not yet been resolved. Therefore, the delay processing unit 109 subsequently stretches the duration of the next sound data "14" using the fixed delay rate (200%). This time stretching resolves the remaining delay time, thus synchronizing the output timing of the DAB broadcast with the output timing of the IP broadcast (timing t3).

[0076] The broadcast receiving apparatus 10 according to the first embodiment increases the proportion of the output time of silent data of the whole of the output time of audio data stretched by delay processing on audio data in the DAB broadcast and decreases the proportion of output time of sound data. Thus, the broadcast receiving apparatus 10 according to the first embodiment allows the output time of sound modulated by delay processing to be reduced.

[0077] A second embodiment of the present invention will be described hereinbelow with reference to Fig. 6 to Figs. 8A and 8B. Fig. 6 is a block diagram illustrating an example of the functional configuration of a broadcast receiving apparatus 10' according to the second embodiment of the present invention. The broadcast receiving apparatus 10' illustrated in Fig. 6 differs from the broadcast receiving apparatus 10 according to the first embodiment (see Fig. 1) in that it includes a delay processing unit 109' instead of the delay processing unit 109.

[0078] The delay processing unit 109' stretches the duration of silent data so that the output time after time stretching has a length during which the remaining delay time can be resolved regardless of the remaining delay Lime of the IP broadcast relative to the DAB broadcast. In other words, in the second embodiment, the length of the output time of silent data after time stretching is not limited by the threshold value th.

Example of Processing Performed by Broadcast Receiving Apparatus 10' (First Example)

[0079] Fig. 7 is a flowchart illustrating an example of processing performed by the broadcast receiving apparatus 10' according to the second embodiment of the present invention. The processing illustrated in Fig. 7 is executed, for example, when the power source of the broadcast receiving apparatus 10' is turned ON.

[0080] First, the DAB buffer 103 stores the audio data in the DAB broadcast received by the first receiver 101 (step S702). The IP buffer 106 stores the audio data in the IP broadcast received by the second receiver 104 (step S704). The delay-time calculating unit 107 calculates the delay time of the IP broadcast relative to the DAB broadcast on the basis of the audio data stored in the DAB buffer 103 and the audio data stored in the IP buffer 106 (step S706). The delay processing unit 109' starts delay processing on the audio data in the DAB broadcast according to the delay time calculated at step S706 (step S708).

[0081] In the delay processing, first, the silent-data detection unit 108 extracts data with a predetermined length from the delay processing target audio data (step S710). The silent-data detection unit 108 determines whether the data with the predetermined length extracted at step S710 is silent data (step S712). If the silent-data detection unit 108 determines that the predetermined length of data is not silent data (step S712: No), the delay processing unit 109' stretches the predetermined length of data using a fixed delay rate for sound data (step S720).

[0082] The delay processing unit 109 determines whether the remaining delay time has been resolved by the time stretching on the sound data at step S720 (for sound data, the delay time calculated at step S706 directly after the start of time stretching) (step S722). If the delay processing unit 109' determines that the remaining delay time has been resolved (step S722: Yes), the delay processing unit 109' terminates the delay processing on the DAB broadcast (step S724), and the broadcast receiving apparatus 10' terminates the series of processing illustrated in Fig. 7.

[0083] In contrast, if the delay processing unit 109' determines that the remaining delay time has not been resolved (step S722: No), the broadcast receiving apparatus 10' executes the processing from step S710 onward.

[0084] If at step S712 the silent-data detection unit 108 determines that the predetermined length of data is silent data (step S712: Yes), the delay-time calculating unit 107 calculates a remaining delay time by subtracting a delay time resolved by the delay processing performed by the delay processing unit 109' from a delay time calculated before the delay processing performed by the delay processing unit 109' (step S714). The silent-data detection unit 108 specifies the length of the silent data (step S716). The delay processing unit 109' stretches the duration of the silent data using a delay rate with which the output time of the silent data allows the remaining delay time to be resolved (step S718). Upon completion of the time stretching on the silent data, the delay processing unit 109' terminates the delay processing on the DAB broadcast (step S724), and the broadcast receiving apparatus 10' terminates the series of processing illustrated in Fig. 7.

Examples of Process Timing

[0085] Figs. 8A and 8B are diagrams illustrating examples of process timing of the broadcast receiving apparatus 10' according to the second embodiment of the present invention. Fig. 8A illustrates an example in which silent data of one frame of audio data is included at the head of delay processing target data. Fig. 8B illustrates an example in which silent data of two frames of audio data is included at the head of delay processing target data. In Figs. 8A and 8B, the content and reception timing of the audio data in the IP broadcast and the DAB broadcast are the same as those in the first embodiment (Figs. 3A and 3B), and the description thereof will be omitted. In the examples illustrated in Figs. 8A and 8B, the IP broadcast is received with a delay of eight frames of audio data relative to the DAB broadcast.

[0086] Different delay rates are applied to the silent data in Figs. 8A and 8B because the lengths of silent data at the head of the delay processing target data differ. In Figs. 8A and 8B, the silent data is expressed as "silent", and the sound data is expressed as "sound".

[0087] In the example illustrated in Fig. 8A, at the delay processing start timing (timing t2), the audio data at the head of the DAB broadcast is silent data "11", and the next audio data is sound data "12". The remaining delay time at that time is of eight frames of audio data.

[0088] In this case, the delay processing unit 109' stretches the duration of the silent data "11" so that the output time of the silent data "11" has a length during which the remaining delay time can be resolved. In the example illustrated in Fig. 8A, the remaining delay time can be resolved by stretching the output time of the silent data "11" to nine frames of audio data (that is, at a delay rate of 900%). This time stretching resolves the remaining delay time, thus synchronizing the output timing of the DAB broadcast with the output timing of the IP broadcast (timing t3).

[0089] In contrast, in the example illustrated in Fig. 8B, at the delay processing start timing (timing t2), the audio data at the head of the DAB broadcast is silent data "11", followed by silent data "12" and sound data "13". At that time, the remaining delay time is of eight frames of audio data 8.

[0090] In this case, the delay processing unit 109' stretches the duration of the audio data α, which is the sum of the silent data "11" and the silent data "12", so that the output time of the audio data α has a length during which the remaining delay time can be resolved. In the example illustrated in Fig. 8B, the remaining delay time can be resolved by stretching the output time of the audio data α to ten frames of audio data (that is, at a delay rate of 500%). This time stretching resolves the remaining delay time, thus synchronizing the output timing of the DAB broadcast with the output timing of the IP broadcast (timing t3).

[0091] With the broadcast receiving apparatus 10' according to the second embodiment, only silent data is output after silent data at the head during the output time of audio data in the DAB broadcast stretched by delay processing. In other words, if the head data is silent data, the output time of silent data constitutes the whole of the stretched output time. Thus, the broadcast receiving apparatus 10' according to the second embodiment can reduce the output time of sound modulated by delay processing.

[0092] Although in the first and second embodiments the DAB broadcast is applied as the first standard broadcast, and the IP broadcast is applied as the second standard broadcast, this is given for mere illustration and is not intended to limit the present invention. In an example, the first standard broadcast may be an FM broadcast, and the second standard broadcast may be an IP broadcast. In another example, the first standard broadcast may be an FM broadcast, and the second standard broadcast may be a DAB broadcast.

[0093] In the first and second embodiments, the delay time of the IP broadcast relative to the DAB broadcast is calculated by comparing the audio data in the DAB broadcast stored in the DAB buffer 103 with the audio data in the IP broadcast stored in the IP buffer 106. This is not intended to limit the present invention. For example, the time difference between time information added to broadcast data in the DAB broadcast and time information added to communication data in the IP broadcast may be calculated as the delay time of the IP broadcast relative to the DAB broadcast.

[0094] It is to be understood that the above embodiments are given for mere illustration and are not intended to limit the technical scope of the present invention. In other words, the present invention can be embodied in various forms without departing from the scope of the claims.

Claims

1. A broadcast receiving apparatus (10, 10') comprising:

a first receiver (101) configured to receive a first standard broadcast;

a second receiver (104) configured to receive a second standard broadcast delayed relative to the first standard broadcast;

a delay-time calculating unit (107) configured to calculate a delay time of the second standard broadcast received by the second receiver (104) relative to the first standard broadcast received by the first receiver (101); and

a delay processing unit (109, 109') configured to synchronize output timing of audio data in the first standard broadcast with output timing of audio data in the second standard broadcast by performing delay processing on the audio data in the first standard broadcast according to the delay time calculated by the delay-time calculating unit (107),

wherein, in the delay processing on the audio data in the first standard broadcast, the delay processing unit (109, 109') is configured to stretch an output time of data containing no sound using a delay rate higher than a delay rate for data containing sound.

2. The broadcast receiving apparatus according to Claim 1, wherein the delay processing unit (109, 109') is configured to stretch the output time of the data containing no sound using a variable delay rate in order that the data containing no sound after being stretched has a predetermined length.

3. The broadcast receiving apparatus according to Claim 1 or 2, wherein the delay processing unit (109, 109') is configured to stretch the output time of the data containing no sound using a variable delay rate in order that the data containing no sound after being stretched has a length during which the delay time calculated by the delay-time calculating unit (107) can be resolved.

4. The broadcast receiving apparatus according to one of Claims 1-3, wherein when the data containing no sound after being stretched becomes longer than a predetermined threshold value (th), the delay processing unit (109, 109') is configured to stretch the output time of the data containing no sound using a variable delay rate in order that the data containing no sound has a length equal to the predetermined threshold value (th).

5. The broadcast receiving apparatus according to one of Claims 1-4, wherein the delay processing unit (109, 109') is configured to stretch the output time of the data containing no sound at predetermined intervals using a fixed delay rate.

6. The broadcast receiving apparatus according to one of Claims 1-5, wherein when a continuous output time of the data containing no sound after being stretched reaches a predetermined threshold value (th), the delay processing unit (109, 109') is configured to detect data containing sound following the data containing no sound and to stretch an output time of the detected data containing sound.

7. The broadcast receiving apparatus according to one of Claims 1-6, wherein the first standard broadcast comprises a DAB broadcast, and the second standard broadcast comprises an IP broadcast.

8. The broadcast receiving apparatus according to one of Claims 1-6, wherein the first standard broadcast comprises an FM broadcast, and the second standard broadcast comprises an IP broadcast.

9. A method for controlling an output of a broadcast receiving apparatus (10, 10') comprising a delay-time calculating unit (107), a delay processing unit (109, 109'), and an output control unit (110) configured to switch between audio data in a first standard broadcast and audio data in a second standard broadcast delayed relative to the first standard broadcast and to output selected audio data, the method comprising the steps of:

calculating, using the delay-time calculating unit (107), a delay time of the second standard broadcast relative to the first standard broadcast; and

performing, using the delay processing unit (109, 109'), delay processing on audio data in the first standard broadcast according to the delay time calculated in the delay-time calculation step to synchronize output timing of the audio data in the first standard broadcast with output timing of the audio data in the second standard broadcast,

wherein, in the step of delay processing on the audio data in the first standard broadcast, the delay processing unit (109, 109') stretches an output time of data containing no sound using a delay rate higher than a delay rate for data containing sound.

Drawing