EP3148102A1

EP3148102A1 - Electronic device and program switching method

Info

Publication number: EP3148102A1
Application number: EP16187821.0A
Authority: EP
Inventors: Iwamoto Yoshihisa
Original assignee: Alpine Electronics Inc
Current assignee: Alpine Electronics Inc
Priority date: 2015-09-24
Filing date: 2016-09-08
Publication date: 2017-03-29
Also published as: JP2017063286A; JP6504980B2

Abstract

An in-vehicle device (10) includes a first tuner (110A), a second tuner (110B), a signal processing unit (120), and a control unit (180) to control each unit. When switching from a currently received program to the same program broadcast by other broadcast station is switched, the control unit (180) determines whether the program of other broadcast station is delayed for the currently received program. When it is determined that the program of other broadcast station is delayed for the currently received program, the control unit sets a reproduction speed of the currently received program, according to content of the program, such that the currently received program is synchronized with the program of other broadcast station. The signal processing unit (120) outputs an audio signal at the set reproduction speed and the currently received program is switched to the program of other broadcast station after the programs are synchronized.

Description

The present invention relates to an electronic device having a function of receiving a radio broadcast and more particularly, to switching to a station broadcasting the same program as a currently received program.
A digital audio broadcast (hereinafter, referred to as the DAB) and a digital audio broadcast + (hereinafter, referred to as the DAB+) are put to practical use in Europe by digitization of an audio broadcast (refer to Patent Literature 1). Digital modulation is an orthogonal frequency division multiplexing (OFDM) method and a compression method is MPEG Audio Layer 2. Furthermore, a radio data system (RDS) is put to practical use in Europe and in the RDS, various digital data are multiplexed to an analog FM broadcast signal and are transmitted.
In an in-vehicle reception device, when a vehicle moves during reception of a program broadcast by a desired station and the reception device deviates from a reception area thereof or a reception environment is deteriorated by a multipath, it is necessary to select a new station. In the DAB/DAB+ or the analog FM broadcast, the same services (programs) may be broadcast at the same time. In the DAB or the RDS, stations broadcasting the same programs are selected automatically, so that inconvenience when a user switches a frequency manually can be eliminated. That is, the reception device receiving the DAB or the RDS has a function of confirming whether a sought broadcast station broadcasts the same program as a program broadcast by a currently selected broadcast station, using multiplexed data (for example, a program identification code (PI), a program name (PS), a frequency list (AF) of the same programs, and a program content identification code (PTY), or a function of seeking a desired broadcast station on the basis of the AF list and switching a current broadcast to an analog broadcast providing the same program as a currently received program or a digital broadcast of a different frequency.
Patent Literature 2 discloses a television broadcast reception device in which, when switching from a digital broadcast to an analog broadcast is executed, an audio output signal based on a broadcast signal before switching fades out, an audio signal based on a broadcast signal after switching fades in, and a sense of discomfort according to switching is reduced. In addition, Patent Literature 2 discloses that audio data is added or erased at a predetermined ratio to absorb a time difference of the digital broadcast and the analog broadcast. Patent Literature 3 discloses a digital broadcast reception device in which display timing is adjusted at the time of switching between a plurality of hierarchies where simulcasting is performed. Patent Literature 4 discloses a reception device in which, with respect to switching control of a broadcast wave type broadcast such as an FM broadcast and an IP type broadcast distributed via a network, a delay time between both the broadcasts is calculated, a reproduction speed of one side is adjusted on the basis of the delay time, and switching is executed at timing when both the broadcasts are synchronized.

Citation List

Patent Literature

Patent Literature 1: JP 10-215196 A
Patent Literature 2: JP 2008-211484 A
Patent Literature 3: JP 2011-259296 A
Patent Literature 4: JP 2013-201469 A

Even when the same program is broadcast by the DAB, the DAB+, or the FM broadcast, a time difference may be generated in broadcast signals between individual programs. In this case, when program switching is executed, it is necessary to eliminate a sense of discomfort for a viewer by adjusting the time difference and outputting audio seamlessly.
FIGS. 8(A) and 8(B) are diagrams conceptually illustrating a time stretch function to be one of time difference adjustment methods. The time stretch function means a process for delaying a time necessary for reproducing an audio signal or a time necessary for outputting the audio signal and reproduces the audio signal at a reproduction speed lower than a normal reproduction speed. FIG. 8(A) illustrates the case in which a program of a service 2 is switched to a program of a service 1 and the program of the service 1 is delayed by 6 seconds as compared with the program of the service 2. In this case, a program is switched to the program of the service 1 after the time stretch function is executed for the program of the service 2 and the program of the service 2 is synchronized with the program of the service 1.
In an example illustrated in FIGS. 8(A) and 8(B), if an extension degree is set to 5% for a time difference (T1 - T2) of the program of the service 2 and the program of the service 1 and the time stretch of the program of the service 2 is executed, the audio signal of the service 2 is reproduced at a reproduction speed lower than the normal reproduction speed. As a result, at a time T3, the audio signals of the program of the service 2 and the program of the service 1 are synchronized and the time difference (T1 - T2) is eliminated. An adjustment time necessary for the time stretch, that is, an adjustment time necessary for the synchronization is represented by the time difference/extension degree (%) between the programs. In the case of FIG. 8(A), because the extension degree is 5%, the adjustment time becomes 120 seconds and in the case of FIG. 8(B), because the extension degree is 10%, an adjustment time from a time T1 to a time T4 becomes 60 seconds. After the adjustment time passes, that is, the synchronization is performed, a program is switched to the program of the service 1.
As such, the time difference between the programs can be adjusted by the time stretch function. However, as illustrated in FIG. 8(A), if the extension degree is small, a sense of discomfort of audio outputs at the time of the time stretch or a sense of discomfort due to a difference of audio outputs at the time of switching the program can be reduced. However, an adjustment time needed until the program is switched increases. Meanwhile, as illustrated in FIG. 8(B), if the extension degree is large, the adjustment time needed until the program is switched can be shortened. However, distortion of the audio outputs at the time of the time stretch or the sense of discomfort due to the difference of the audio outputs at the time of switching the program occurs. Particularly, in the case of a music program, if a rhythm or a tempo of an output musical composition changes, the user feels the change sensitively and the sense of discomfort becomes easy to occur.
The present invention has been made to address the problems according to the related art and an object of the present invention is to provide an electronic device capable of switching a program seamlessly without causing a sense of discomfort, a program switching program, and a program switching method.
The invention relates to an electronic device and method according to the independent claims. The invention further relates to a computer program product as described herein. Embodiments are disclosed in the dependent claims. An electronic device according to an aspect of the present invention is one having a function of receiving a radio broadcast, and the device includes: a reception means configured to receive the radio broadcast; a reproduction means configured to reproduce a broadcast signal of the received radio broadcast; an output means configured to output audio of the reproduced broadcast signal; and a control means configured to control the reproduction means, when switching from a currently received program to the same program broadcast by other broadcast station is executed, wherein the control means includes a determination means that determines whether the same program is delayed for the currently received program and a setting means that sets a reproduction speed of the currently received program or an extension degree to extend the currently received program, according to content of the program, such that the currently received program is synchronized with the same program, when it is determined by the determination means that the same program is delayed for the currently received program.
According to another aspect of the present invention, there is provided an electronic device having a function of receiving a radio broadcast. The electronic device includes a reception means configured to receive the radio broadcast; a reproduction means configured to reproduce a broadcast signal of the received radio broadcast; an output means configured to output audio of the reproduced broadcast signal; and a control means configured to control the reproduction means, when switching from a currently received program to the same program broadcast by other broadcast station is executed. The control means includes a determination means that determines whether the same program is delayed for the currently received program and a setting means that sets an extension degree to extend the currently received program, according to content of the program, such that a time difference of the currently received program and the same program is eliminated, when it is determined by the determination means that the same program is delayed for the currently received program.
Preferably, the setting means sets a first reproduction speed or a first extension degree when content of a program belongs to a first type and sets a second reproduction speed or a second extension degree when the content of the program belongs to a second type. Preferably, the first type is a music program, the second type is an audio program, and the first reproduction speed is lower than the second reproduction speed. Preferably, the first type is a music program, the second type is an audio program, and the first extension degree is smaller than the second extension degree. Preferably, the setting means includes a table defining content of a program and a reproduction speed or an extension degree corresponding to the content of the program and the setting means sets the reproduction speed or the extension degree according to the table. Preferably, the setting means identifies content of a program, on the basis of program identification information included in a currently received broadcast signal. Preferably, the control means further includes a switching control means that controls switching of the reception means and the switching control means causes a program to be received from other broadcast station, after the currently received program is synchronized with the same program. Preferably, the determination means compares a broadcast signal of the currently received program and a broadcast signal of the same program and calculates a time difference of both the programs and the switching control means causes a program to be received from other broadcast station, after a reproduction time acquired from the time difference and the extension degree or the time difference and the reproduction speed passes. Preferably, the electronic device further includes a communication means configured to perform communication with an external network and other broadcast station is a broadcast station that distributes a program via the communication means. Preferably, the reception means includes a first reception means and a second reception means and the second reception means searches the same program as a current program, when the first reception means receives the current program.
According to another aspect of the present invention, there is provided a computer program product comprising software code sections configured to implement a program switching program and that are executed by an electronic device having a function of receiving a radio broadcast. The program switching program includes, when switching from a currently received program to the same program broadcast by other broadcast station is executed, determining whether the same program is delayed for the currently received program; setting an extension degree to extend the currently received program, according to content of the program, such that a time difference of the currently received program and the same program is eliminated, when it is determined that the same program is delayed for the currently received program; and executing switching to the same program of other broadcast station, after extending the currently received program.
According to another aspect of the present invention, there is provided a program switching method in an electronic device having a function of receiving a radio broadcast. The program switching method includes, when switching from a currently received program to the same program broadcast by other broadcast station is executed, determining whether the same program is delayed for the currently received program; setting an extension degree to extend the currently received program, according to content of the program, such that a time difference of the currently received program and the same program is eliminated, when it is determined that the same program is delayed for the currently received program; and executing switching to the same program of other broadcast station, after extending the currently received program.

Advantageous Effects of Invention

According to the present invention, when a program is switched, a reproduction speed or an extension degree of a currently received program is set according to content of the program. Therefore, a program switching time can be shortened without causing a sense of discomfort, according to the content of the program.

Brief Description of Drawings

FIG. 1 is a block diagram illustrating a configuration example of an in-vehicle device having a radio reception function according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating an example of a broadcast signal frame structure (data structure) adopted in a DAB broadcast represented by a digital radio broadcast.
FIG. 3 is a diagram illustrating a functional configuration example of a program switching program according to this embodiment.
FIG. 4 is a diagram illustrating an example of a table defining a relation of a program type (PTY) and a delay ratio of a time stretch according to this embodiment.
FIG. 5 is a flowchart illustrating a program switching program between the same programs in an in-vehicle device according to an embodiment of the present invention.
FIG. 6 is a diagram illustrating an effect of a program switching operation according to an embodiment of the present invention.
FIG. 7 is a diagram illustrating a relation of an extension degree of time stretch, an adjustment time, and a reproduction speed according to an embodiment of the present invention.
FIGS. 8(A) and 8(B) are diagrams illustrating a time stretch function to be one of time difference adjustment methods.
FIG. 9 is a block diagram illustrating a configuration example of an in-vehicle device having a radio reception function according to another embodiment of the present invention.

Next, embodiments of the present invention will be described in detail with reference to the drawings. An electronic device according to the present invention is an in-vehicle device mounted on a moving object such as a vehicle or a portable terminal (a multifunctional portable terminal represented by a smart phone, a tablet terminal, or a portable personal computer) capable of being carried into the vehicle, which includes at least a function of receiving a radio broadcast. The electronic device according to the present invention can receive a digital radio broadcast or an analog radio broadcast, for example, DAB, DAB+, and RDS broadcasts. In addition, the electronic device according to the present invention can include a function of receiving an Internet broadcast via a network in addition to the radio broadcast, a function of receiving a television broadcast, a navigation function, a function of reproducing audio/video data, and a data communication function.

[Embodiment]

Next, an embodiment of the present invention will be described. FIG. 1 is a block diagram illustrating a configuration example of an in-vehicle device having a radio reception function according to this embodiment. An in-vehicle device 10 includes a first antenna 100A, a first tuner 110A that receives a broadcast signal of a broadcast station (frequency) selected via the first antenna 100A, a second antenna 100B, a second tuner 110B that receives a broadcast signal of a broadcast station (frequency) selected via the second antenna 100B, a signal processing unit 120 that receives the broadcast signals from the first and second tuners 110A and 110B and executes a process necessary for each broadcast signal, an amplifier 130 that amplifies an audio signal processed by the signal processing unit 120, a speaker 132 that outputs the audio signal amplified by the amplifier 130, a display unit 140 that displays data decoded by the signal processing unit 120, a storage unit 150, an input unit 160 that receives an input from a user, an interface (I/F) unit 170 that enables connection with an external device such as a navigation device, and a control unit 180 that controls the first and second tuners 110A and 110B, the signal processing unit 120, and the amplifier 130.
In the above configuration, the in-vehicle device 10 includes the two tuners. However, the present invention is not limited thereto and the number of tuners may be one or more and may be three or more. When the in-vehicle device 10 includes the two tuners, one tuner is caused to function as a main tuner and the other tuner is caused to function as a sub tuner, thereby causing the sub tuner to seek an alternative station while the main tuner receives a program from a certain broadcast station. In addition, the tuners may receive a digital radio broadcast and/or an analog radio broadcast or one tuner may receive the digital radio broadcast and the other tuner may receive the analog radio broadcast. The in-vehicle device 10 can include a function of performing communication with an external network.
In a preferred aspect, the first tuner 110A includes an RF amplifier that receives an RF signal from the antenna 100A and amplifies the RF signal, a tuning circuit that selects a frequency signal of a desired station from the amplified RF signal, a mixer that mixes a frequency signal from a local transmitter and the RF signal and generates an intermediate frequency (IF) signal, and an S-meter circuit that DC-detects the intermediate frequency signal and extracts a reception field strength signal (S-meter signal) thereof. In addition, the first tuner 110A converts the intermediate frequency (IF) signal and the S-meter signal into digital signals by an analog/digital converter (ADC) and outputs the digital signals to the signal processing unit 120 and the control unit 180. The second tuner 110B also has the same configuration as the configuration of the first tuner 110A. The first and second tuners 110A and 110B can select the same broadcast stations (frequencies) or different broadcast stations, according to an instruction from the control unit 180.
The signal processing unit 120 is configured using a digital signal processor (DSP), for example. The signal processing unit 120 executes various processes for the digital signals output from the first and second tuners 110A and 110B. For example, signal processes such as FFT, digital filtering, signal synchronization, time/frequency deinterleave, audio decoding, data decoding, and phase diversity are executed for the digital radio broadcast signal of the DAB/DAB+. In addition, decoding of data superimposed on a radio broadcast is performed for the RDS radio broadcast signal. In addition, the signal processing unit 120 can include a buffer to accumulate an audio signal and can adjust a reproduction speed or an output speed of the audio signal by changing a read speed of the audio signal from the buffer. In addition, the signal processing unit 120 includes a digital/analog converter (DAC) and converts a decoded digital audio signal into an analog audio signal and provides the analog audio signal to the amplifier 130.
The control unit 180 is configured using a microcontroller and a microprocessor, for example, and controls each unit by executing a program stored in a memory such as a ROM/RAM. In this embodiment, the control unit 180 has a function of, when reception sensitivity of a program of a certain broadcast station is deteriorated during being received by the first tuner 110A or the first tuner 110A deviates from a reception area, causing the second tuner 110B to search a broadcast station broadcasting the same program as the currently received program and executing automatic switching to the same program. When the program of the switching destination is delayed for the currently received program at the time of executing switching of the same program, switching of the program is executed after executing the time stretch function for the currently received program and eliminating the time difference between the programs. Even if the in-vehicle device 10 includes only one tuner, an alternative broadcast station may be searched by a time division process.
Next, a detailed operation of the in-vehicle device 10 according to this embodiment will be described. FIG. 2 illustrates a frame structure of a DAB broadcast signal of a mode II adopted in the DAB broadcast represented by the digital audio broadcast. A length of one frame is 24 ms. The frame structure includes a synchronization SYNC of 2 symbols, a fast information channel FIC of 3 symbols, and a data field DFL of 72 symbols. The synchronization SYNC includes a null symbol and a phase reference symbol PRS used to recognize a start point of a frame. The fast information channel FIC includes fast information blocks FIB1 to FIB3 of 3 symbols and includes time/date data, ensembles/labels (names showing contents of broadcast signals including a plurality of services (programs)), service labels (names showing individual service contents), service component labels (names showing contents (program names) more detailed than the service labels), array data of the services, and program type codes PTY showing program contents. The data field DFL is divided into 72 data fields (symbols) and a broadcast signal of a predetermined service (program) is inserted into each data field, so that broadcast signals of 6 to 8 services (programs) can be simultaneously transmitted from one broadcast station. A correspondence relation of the data fields and the services (programs) is designated by the array data of the services included in the fast information channel FIC.
Each of the fast information blocks FIB1 to FIB3 of the fast information channel FIC includes a hierarchical structure. Each fast information block FIB includes an FIB data field of 256 bits and a cyclic redundancy code (CRC). The FIB data field includes a plurality of FIG data field groups (Fast Information Groups). Each FIG includes a FIG type, a byte length (Length) of each FIG, and a FIG data field and various data such as a service label and a program type code PTY are inserted into the FIG data field.
FIG. 3 is a block diagram illustrating a functional configuration of a switching program of a program executed by the control unit 180. As described above, when the reception sensitivity of the broadcast station of the currently received program is deteriorated, a program switching program 200 executes automatic switching to a broadcast station broadcasting the same program. The program switching program 200 includes a switching determination unit 210, an alternative broadcast station search unit 220, a delay determination unit 230, an extension degree setting unit 240, a time stretch control unit 250, and a program switching control unit 260.
The switching determination unit 210 determines whether it is necessary to execute switching from a currently received program of a currently selected broadcast station to a program of another broadcast station. In a preferred example, the switching determination unit 210 determines whether a program is switched on the basis of reception sensitivity of a radio broadcast. For example, when a level of a field strength signal from the first tuner 110A becomes equal to or smaller than a threshold value at the time of viewing the program of the broadcast station received by the first tuner 110A to be a main tuner, the switching determination unit 210 determines that a reception environment has been deteriorated and determines that switching of the broadcast station is necessary. In addition, when a switching instruction from a user is input from the input unit 160, the switching determination unit 210 may determine that switching is necessary.
When it is determined by the switching determination unit 210 that switching of the program is necessary, the alternative broadcast station search unit 220 searches an alternative broadcast station broadcasting the same program as the currently received program, in response to a determination result. For example, the alternative broadcast station search unit 220 causes the second tuner 110B to be a sub tuner to search an alternative broadcast station having superior reception sensitivity. For the convenience of description, the currently received program of the currently selected broadcast station is called a "program A" and a program of a broadcast station of a switching destination is called a "program B". The "program A" and the "program B" are the same programs.
A method of searching the alternative broadcast station is not limited in particular. For example, when the first tuner 110A receives the program A by the DAB broadcast, the broadcast station broadcasting the same program B as the program A is searched by causing the second tuner 110B to scan other frequency band of the DAB/DAB+ broadcast. At this time, it can be determined whether the program A and the program B are the same programs, by referring to program identification information such as a program type (PTY), a program name (PS), and a program identification code (PI) included in the DAB broadcast. In addition, the second tuner 110B may be caused to search an RDS analog FM broadcast. In this case, it can be determined whether the programs are the same programs, by referring to program identification information such as a program type (PTY), a program name (PS), and a program identification code (PI) included in data superimposed on an analog broadcast. In addition to the above determination methods, a part of a broadcast signal received by the first tuner 110A is captured, a part of a broadcast signal received by the second tuner 110B is captured, and both the signals are compared, so that it can be determined whether the programs are the same programs.
As another search method, when the second tuner 110B makes a frequency list (AF) of the same programs by a background operation, the second tuner 110B may search the alternative broadcast station according to the frequency list. As other method, when program guide information to show a broadcast station broadcasting the same program B as the program A is included in the currently received broadcast signal, the alternative broadcast station may be searched on the basis of the program guide information.
When the alternative broadcast station broadcasting the same program B as the program A is found, the alternative broadcast station search unit 220 starts reception of the program B by the second tuner 110B. The received broadcast signal is processed by the signal processing unit 120 and is accumulated in a buffer memory.
The delay determination unit 230 determines whether the program B after switching is delayed for the currently received program A. The delay determination unit 230 causes the signal processing unit 120 to capture the broadcast signal of the program A received by the first tuner 110A during a constant period and capture the broadcast signal of the program B received by the second tuner 110B during the constant period, compares the captured signals, and detects a point of time when both the signals are reproduced at the same time, so that the delay determination unit 230 determines the delay of the program B for the program A and calculates a time difference of the programs A and B. For example, as illustrated in FIGS. 8(A) and 8(B), a time difference (T1 - T2) of the services 1 and 2 is calculated.
The extension degree setting unit 240 sets an extension degree when the time stretch is executed. The extension degree setting unit 240 sets the extension degree according to the content of the currently received program. In other words, in the case of the content of the program sensitive to the lowered reproduction speed, the extension degree setting unit 240 sets the extension degree relatively small. In contrast, in the case of the content of the program not sensitive to the lowered reproduction speed, the extension degree setting unit 240 sets the extension degree large. More specifically, the extension degree setting unit 240 determines the content of the program on the basis of the program type (PTY) functioning as the program identification information. When the content of the program belongs to a music program, the extension degree setting unit 240 sets the extension degree small and when the content of the program belongs to an audio program (for example, news or dramas), the extension degree setting unit 240 sets the extension degree large.
In this embodiment, a table defining a relation of the program type (PTY) and the extension degree is previously stored in the storage unit 150. FIG. 4 illustrates an example of the table. For example, it is assumed that the extension degree by the time stretch can be set in a range of 1 to 10%. The extension degree is previously determined for each of the program types (PTY) that can be acquired from the DAB broadcast or the RDS broadcast. For example, when the program types are news, current affairs, information, sports, education, drama, culture, and science, the extension degree is set to a maximum of 10%. These program contents are audio broadcasts not causing a large sense of discomfort, even when the reproduction speed is lowered relatively largely. Meanwhile, when the program types are pop music, rock music, and easy listening music, the extension degree is set to 5% lower than the extension degree of the audio program. These program contents are music programs causing a sense of discomfort easily, when the reproduction speed is lowered relatively largely. When the program type cannot be acquired, the extension degree is set to 5% equal to the extension degree of the music program. A value of the extension degree described herein is exemplary and a range of the extension degree is also exemplary. Here, the relation of the program type (PTY) and the extension degree is defined. However, if the content of the program can be determined from program identification information other than the program type (PTY), a table defining a relation of the program identification information and the extension degree may be prepared.
The time stretch control unit 250 controls the delay of reproduction of the currently received program of the signal processing unit 120, according to the extension degree set by the extension degree setting unit 240. That is, the time stretch control unit 250 controls a reproduction speed of an audio signal reproduced by the signal processing unit 120 or an output speed of an audio signal output from the signal processing unit 120, according to the extension degree. A method of delaying the reproduction is not limited in particular. For example, in the signal processing unit 120, a decoded audio signal is accumulated in the buffer memory and a read speed of audio data from the buffer memory is lowered.
The program switching control unit 260 executes switching from the program A of the currently selected broadcast station to the program B of the broadcast station of the switching destination, after executing the time stretch. That is, after a point of time when the currently received program A and the program B of the switching destination are synchronized, the program switching control unit 260 causes the first tuner 110A to execute switching from the broadcast station of the program A to the broadcast station of the program B. The point of time when the programs A and B are synchronized is a point of time when a value (time difference/extension degree) obtained by dividing the time difference calculated by the delay determination unit 230 by the extension degree, that is, an adjustment time has passed. As a result, audio of the program B synchronized with the program A is output seamlessly from the speaker 132.
In the above example, the first tuner 110A to be the main tuner executes switching from the program A to the program B. However, switching of the program may be executed by causing the audio signal of the program A received by the first tuner 110A not to be output from the signal processing unit 120 and causing the audio signal of the program B received by the second tuner 110B to be output from the signal processing unit 120.
FIG. 5 is a flowchart illustrating a program switching operation in the in-vehicle device according to this embodiment. Here, it is assumed that the broadcast signal received by the first tuner 110A to be the main tuner is output and the second tuner 110B to be the sub tuner searches the alternative broadcast station.
First, the program A is received by the first tuner 110A and the audio of the program A is output from the speaker 132 (S100). During reception of the program A, the switching determination unit 210 monitors whether switching to other broadcast station is necessary (S102). For example, when a fault of a multipath occurs or the in-vehicle device deviates from a reception area during movement of the vehicle, a level of a field strength signal decreases to a threshold value or less and it is determined that switching of the broadcast station is necessary. Deterioration of the reception sensitivity may be determined by referring to information other than the field strength signal, for example, an error rate of the received broadcast signal.
When it is determined by the switching determination unit 210 that switching is necessary, the alternative broadcast station search unit 220 causes the second tuner 110B to search an alternative broadcast station broadcasting the same program B (S104). When the alternative broadcast station broadcasting the program B is not found, the process ends. When the alternative broadcast station broadcasting the program B having the superior reception sensitivity is found (S106), it is determined by the delay determination unit 230 whether the program B is delayed for the program A (S108). When the program B is not delayed for the program A, the process ends because the time stretch of the program A is unnecessary. When it is determined that the program B is delayed for the program A, the time difference (T1 - T2) is calculated at the same time. Next, the extension degree according to the program type is set by the extension degree setting unit 240 (S110). That is, the extension degree setting unit 240 sets the extension degree by referring to the table illustrated in FIG. 4, on the basis of the program type (PTY) of the program A.
If the extension degree is set, the time stretch control unit 250 executes the time stretch of the currently received program A, according to the set extension degree. That is, the signal processing unit 120 delays reproduction of the program A, according to the extension degree (S112). When the time stretch ends, that is, the adjustment time ends and the programs A and B are synchronized, the program switching control unit 260 instructs the first tuner 110A to execute switching from the program A to the program B. As a result, the first tuner 110A starts reception of the program B and the audio of the program B processed by the signal processing unit 120 and the amplifier 130 is output from the speaker 132 (S116).
When the broadcast station broadcasting the program B is not found (including when the reception sensitivity of the program B is not superior), the program switching program 200 can execute switching to a program not to be the same program as the program A. In addition, when the programs A and B are synchronized from the beginning or the program B is not delayed for the program A, switching to the program B is executed immediately without executing the time stretch. In the case of the latter, after switching, the audio of the program A accumulated in the buffer memory during a period corresponding to the time difference of the programs A and B is output earlier. Then, an output of the audio of the program B accumulated in the buffer memory during the same period starts and the audio of the programs A and B is output seamlessly.
FIG. 6 illustrates a specific example of the program switching operation according to this embodiment. A time difference of the programs A and B is set to 6 seconds, an example of the case in which a music program is extended at an extension degree of 5% is illustrated at an upper step, and an example of the case in which an audio program is extended at an extension degree of 10% is illustrated at a lower step. Ts shows timing when synchronization of the programs A and B is completed. In an audio program of which a program type (PTY) is a news program or an information program, even though an extension degree of the time stretch increases (a reproduction speed increases), a sense of discomfort is small. For this reason, the adjustment time Ts until the synchronization can be shortened and a time until the program is switched can be shortened. Meanwhile, in a music program of which a program type (PTY) is pop music and rock music, an extension degree is set small and a sense of discomfort is reduced. Tp shows that a time until the audio program is switched is more shortened than a time until the music program is switched. As such, when there is a time difference between the same programs, the extension degree of the time stretch or the reproduction speed is changed according to the contents of the programs, so that seamless program switching with a small sense of discomfort is realized while the time until switching is executed is shortened maximally.
FIG. 7 illustrates a relation of an adjustment time (time difference/extension degree) when an extension degree of the time stretch is changed and a reproduction speed of a time stretched audio signal, in the case in which a time difference between programs is 6 seconds. In the case in which a reproduction speed when the extension degree is 1% is set to S, when the extension degree increases, the adjustment time is shortened and the reproduction speed increases.
In this embodiment, switching between the programs in the DAB/DAB+ is mainly described. However, the present invention may be applied to switching of programs between an analog broadcast and a digital broadcast, like switching from the FM broadcast to the DAB broadcast or switching from the DAB broadcast to the FM broadcast.
FIG. 9 is a block diagram illustrating a configuration example of an in-vehicle device having a radio reception function according to another embodiment of the present invention. An in-vehicle device 10A according to this embodiment includes a function of performing communication with an external network. When an Internet broadcast reception unit 190 is connected to the Internet by the communication function, the Internet broadcast reception unit 190 receives a broadcast program distributed on the Internet. Audio data in data of the broadcast program received by the Internet broadcast reception unit 190 is provided to a signal processing unit 120 and a necessary process is executed therein. When it is determined by a switching determination unit 210 of a program switching program 200 that it is necessary to switch a program, an alternative broadcast station search unit 220 searches an Internet broadcast distributing the same program as a program of a radio broadcast, on the basis of program identification information included in the radio broadcast. A delay determination unit 230 determines whether delay is generated between a currently received program A of the radio broadcast and a program B of the searched Internet broadcast. When the program B is delayed for the program A, a time stretch function is executed by the same method as the method according to the embodiment and the program B is synchronized with the program A.
As a result, even when switching from the radio broadcast to the Internet broadcast is executed, the program can be switched as early as possible without causing a sense of discomfort. In the above example, the alternative broadcast station search unit 220 searches the Internet broadcast distributing the same program as the program of the radio broadcast. However, if a site of a simultaneous broadcast on the Internet distributing the same program as the program of the radio broadcast is known, the Internet broadcast reception unit 190 can receive the simultaneous broadcast from the known site, without searching an alternative station.

The preferred embodiments of the present invention have been described in detail. However, the present invention is not limited to the certain embodiments and various changes and modifications can be made without departing from the scope of the claims.

Reference Signs List

10: in-vehicle device	100A: first antenna
100B: second antenna	110A: first tuner
110B: second tuner	120: signal processing unit
130: amplifier	132: speaker
140: display unit	150: storage unit
160: input unit	170: interface (I/F) unit
180: control unit	200: program switching program
210: switching determination unit	220: alternative broadcast station search unit
230: delay determination unit	240: extension degree setting unit
250: time stretch control unit	260: program switching control unit

Claims

An electronic device having a function of receiving a radio broadcast, comprising:
a reception means configured to receive the radio broadcast;

a reproduction means configured to reproduce a broadcast signal of the received radio broadcast;

an output means configured to output audio of the reproduced broadcast signal; and

a control means configured to control the reproduction means, when switching from a currently received program to the same program broadcast by other broadcast station is executed,
wherein the control means includes a determination means that is configured to determine whether the same program is delayed for the currently received program and a setting means that is configured to set a reproduction speed of the currently received program or an extension degree to extend the currently received program, according to content of the program, such that the currently received program is synchronized with the same program, when it is determined by the determination means that the same program is delayed for the currently received program.
The electronic device according to claim 1,
wherein the setting means is configured to set a first reproduction speed or a first extension degree when content of a program belongs to a first type and to set a second reproduction speed or a second extension degree when the content of the program belongs to a second type.
The electronic device according to claim 2,
wherein the first type is a music program, the second type is an audio program, and the first reproduction speed is lower than the second reproduction speed.
The electronic device according to claim 2 or 3,
wherein the first type is a music program, the second type is an audio program, and the first extension degree is smaller than the second extension degree.
The electronic device according to any one of claims 1 to 4,
wherein the setting means includes a table defining content of a program and a reproduction speed or an extension degree corresponding to the content of the program and the setting means is configured to set the reproduction speed or the extension degree according to the table.
The electronic device according to any one of claims 1 to 5,
wherein the setting means is configured to identify content of a program, on the basis of program identification information included in a currently received broadcast signal.
The electronic device according to any one of claims 1 to 6,
wherein the control means further includes a switching control means that is configured to control switching of the reception means and the switching control means is configured to cause a program to be received from other broadcast station, after the currently received program is synchronized with the same program.
The electronic device according to any one of claims 1 to 7,
wherein the determination means is configured to compare a broadcast signal of the currently received program and a broadcast signal of the same program and to calculate a time difference of both the programs and the switching control means is configured to cause a program to be received from other broadcast station, after a reproduction time acquired from the time difference and the extension degree or the time difference and the reproduction speed passes.
The electronic device according to any one of claims 1 to 8, further comprising:
a communication means configured to perform communication with an external network,
wherein other broadcast station is a broadcast station that distributes a program via the communication means.
The electronic device according to any one of claims 1 to 9,
wherein the reception means includes a first reception means and a second reception means and the second reception means is configured to search the same program as a current program, when the first reception means receives the current program.
A program switching method in an electronic device having a function of receiving a radio broadcast, comprising:
when switching from a currently received program to the same program broadcast by other broadcast station is executed, determining whether the same program is delayed for the currently received program;

setting an extension degree to extend the currently received program, according to content of the program, such that a time difference of the currently received program and the same program is eliminated, when it is determined that the same program is delayed for the currently received program; and

executing switching to the same program of other broadcast station, after extending the currently received program.
The program switching method according to claim 11,
wherein, in the setting of the extension degree, a first extension degree is set when content of a program belongs to a first type and a second extension degree is set when the content of the program belongs to a second type.
The program switching method according to claim 12,
wherein the first type is a music program, the second type is an audio program, and the first extension degree is smaller than the second extension degree.
The program switching method according to any one of claims 11 to 13,
wherein, in the setting of the extension degree, the extension degree is set according to a table defining content of a program and a reproduction speed or an extension degree corresponding to the content of the program.
The program switching method according to any one of claims 11 to 14,
wherein, in the setting of the extension degree, content of a program is identified on the basis of program identification information included in a currently received broadcast signal.