EP3208955A1

EP3208955A1 - Radio receiver

Info

Publication number: EP3208955A1
Application number: EP16206321.8A
Authority: EP
Inventors: Hiroyuki Taniguchi
Original assignee: Alpine Electronics Inc
Current assignee: Alpine Electronics Inc
Priority date: 2016-02-17
Filing date: 2016-12-22
Publication date: 2017-08-23
Anticipated expiration: 2036-12-22
Also published as: JP2017147623A; JP6556642B2; EP3208955B1

Abstract

When sound to be output is switched from radio broadcasting to IP radio broadcasting, delay of output of received sound in the radio broadcasting is increased by temporally expanding only blank sections in the sound if the received sound of the radio broadcasting has a large amount of blank sections and delay of output of received sound in the radio broadcasting is increased by temporally expanding the entire sound if the received sound does not have a large amount of blank sections. When the delay time matches a delay time of the IP radio broadcasting relative to the radio broadcasting, the sound to be output is switched from the sound of the radio broadcasting to the sound of the IP radio broadcasting.

Description

The present invention relates to a technique, employed in a radio receiver, of switching a reception target from broadcasting being received to another broadcasting having content the same as that of the broadcasting being received.
As a technique, employed in a radio receiver, of changing a reception target from broadcasting being received to broadcasting having content the same as that of the broadcasting being received (that is, broadcasting having the relationship of simultaneous broadcasting with the broadcasting being received), a technique, employed in a radio receiver which receives broadcasting of broadcasting waves and IP radio broadcasting having the relationship of simultaneous broadcasting with the broadcasting of broadcasting waves, of seamlessly switching output sound from sound received from the broadcasting of broadcasting waves to sound received by the IP radio broadcasting is widely used (refer to JP 2013-201469 A ).
Here, in this technique, the sound received from the broadcasting of broadcasting waves is output at a low reproduction speed so that the output of the sound received from the broadcasting of broadcasting waves is delayed by a delay time of the IP radio broadcasting relative to the broadcasting of broadcasting waves, and thereafter, the sound to be output is switched from the sound received from the broadcasting of broadcasting waves to the sound received from the IP radio broadcasting. In this way, seamless switching is realized.
Furthermore, as such a technique of delaying sound, a technique of delaying sound by extending periods of blank sections in the sound is also widely used (refer to JP 2015-156584 A , for example).
According to the technique of delaying a reproduction speed of sound received from the broadcasting of broadcasting waves described above at a time of outputting so that the output of the sound received from the broadcasting of broadcasting waves is delayed by a delay time of the IP radio broadcasting relative to the broadcasting of broadcasting waves, a pitch of output sound is changed from an original pitch of the sound received from the broadcasting of broadcasting waves. Although the change of a pitch may be suppressed if reduction of a reproduction speed is suppressed, in this case, a long period of time is required until the sound is delayed by the predetermined delay time.
On the other hand, in the technique of delaying sound by expanding blank sections in the sound described above, in a case where the sound has a small amount of blank sections, that is, the sound is music or the like, a long period of time is required until the sound is delayed by the predetermined delay time.
Accordingly, it is an object of the present invention to perform seamless switching of sound to be output as rapid as possible irrespective of an amount of blank sections of the sound in a radio receiver which seamlessly switches sound to be output from sound received from broadcasting being received to sound to be received from broadcasting having the same content as the broadcasting being received.
The invention relates to a radio receiver according to claim 1. Embodiments are disclosed in the dependent claims.
According to an aspect, the present invention provides a radio receiver capable of receiving radio broadcasting and parallel broadcasting in which sound having the same content as the radio broadcasting is transmitted after being delayed relative to the radio broadcasting. The radio receiver includes an output unit configured to output sound to a user, a radio receiving unit configured to receive the radio broadcasting and output received sound to the output unit, a parallel broadcasting receiving unit configured to receive the parallel broadcasting and output received sound to the output unit, a delay unit configured to delay the sound output by the radio receiving unit to the output unit, a sound type determination unit configured to determine whether sound being received by the radio receiving unit is large blank section sound having a rate of blank sections equal to or larger than a predetermined level or determine whether sound received by the radio receiving unit is small blank section sound having a rate of blank sections which is not equal to or larger than the predetermined level, and a controller configured to control switching of sound to be output to the user from the sound received by the radio receiving unit to the sound received by the parallel broadcasting receiving unit. The output unit selectively outputs to the user one of the sound output from the radio receiving unit and the sound output from the parallel broadcasting receiving unit under control of the controller. The delay unit performs, under control of the controller, a blank section expansion delay operation of increasing the delay of the sound by temporary expanding only the blank sections of the sound output from the radio receiving unit, and an entire expansion delay operation of increasing the delay of the sound by temporally expanding the sound output from the radio receiving unit in a uniform manner. The controller causes the delay unit to perform the blank section expansion delay operation in a case where the sound type determination unit determines that the sound received by the radio receiving unit is the large blank section sound, and causes the delay unit to perform the entire expansion delay operation in a case where the sound type determination unit determines that the sound received by the radio receiving unit is the small blank section sound, and causes the output unit to switch the sound to be output to the user from the sound output from the radio receiving unit to the sound output from the parallel broadcasting receiving unit if a delay time of the delay of the sound output from the radio receiving unit matches a delay time of the sound received by the parallel broadcasting receiving unit relative to the sound received by the radio receiving unit.
According to the radio receiver, in a case where a rate of the blank section of the audio of the radio broadcasting required to be delayed for seamless switching from the radio broadcasting to the parallel broadcasting indicates sound equal to or larger than a predetermined level, only the blank sections of the sound of the radio broadcasting is temporally expanded so that the sound of the radio broadcasting is delayed, and otherwise, the sound of the radio broadcasting is temporally expanded in a uniform manner so that the sound of the radio broadcasting is delayed. Accordingly, in a case where an amount of blank sections of the sound of the radio broadcasting is large, the sound may be delayed by the delay time of the parallel broadcasting relative to the radio broadcasting, and even in a case where an amount of blank sections is small or a blank section is not included in the sound of the radio broadcasting, the sound may be reliably delayed within a certain period by the delay time of the parallel broadcasting relative to the radio broadcasting.
Therefore, according to the present invention, the seamless switching of sound from the radio broadcasting to the parallel broadcasting may be rapidly performed irrespective of an amount of blank sections.
Here, in the radio receiver, the controller may control the delay unit such that the blank section expansion delay operation is stopped and the entire expansion delay operation is performed when an increase rate of the delay time of the delay of the sound output from the radio receiving unit by the delay unit becomes equal to or smaller than a predetermined level during a period in which the delay unit performs the blank section expansion delay operation.
Furthermore, in the radio receiver, the controller may control the delay unit so that the delay unit stops the entire expansion delay operation and performs the blank section expansion delay operation when a rate of the blank sections of the sound received by the radio receiving unit becomes equal to or larger than a predetermined threshold value in a period of time in which the delay unit performs the entire expansion delay operation.
With this configuration, even in a case where an amount of blank sections in the sound of the radio broadcasting is changed after the delay unit starts the delay of the sound of the radio broadcasting, the seamless switching from the radio broadcasting to the parallel broadcasting may be rapidly completed.
In the radio receiver, the entire expansion delay operation may increase delay of the sound output from the radio receiving unit by converting the sound into sound of a lower reproduction speed or may perform time stretch on the sound output from the radio receiving unit without changing a pitch.
Furthermore, in the radio receiver, the sound type determination unit may identify a type of a program received by the radio receiving unit, determine that sound received by the radio receiving unit is the small blank section sound in a case where at least the identified type of the program is a music program, and determine that the sound received by the radio receiving unit is the large blank section sound in a case where the identified type of the program is news.
In the radio receiver, the parallel broadcasting may be IP radio broadcasting, and the parallel broadcasting receiving unit may be an IP radio player which receives the IP radio broadcasting and outputs received sound. Moreover, the radio broadcasting may be at least one of digital radio broadcasting and analog radio broadcasting.
Furthermore, the radio receiver may be an in-vehicle radio receiver installed in a vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a block diagram illustrating a configuration of a radio broadcasting system according to an embodiment of the present invention;
Fig. 2 is a block diagram illustrating a configuration of a radio broadcasting receiver according to an embodiment of the present invention;
Figs. 3A and 3B are diagrams illustrating a delay process algorithm employed in an embodiment of the present invention;
Fig. 4 is a flowchart illustrating a seamless switching process according to an embodiment of the present invention;
Fig. 5 is a diagram illustrating an operation of the seamless switching process according to an embodiment of the present invention;
Fig. 6 is a diagram illustrating an operation of the seamless switching process according to an embodiment of the present invention;
Fig. 7 is a flowchart illustrating another seamless switching process according to an embodiment of the present invention; and
Fig. 8 is a diagram illustrating an operation of the other seamless switching process according to an embodiment of the present invention.

Hereinafter, an embodiment of the present invention will be described.
Fig. 1 is a diagram illustrating a configuration of a radio broadcasting system according to an embodiment.
As illustrated in Fig. 1, a radio broadcasting receiver 1 of this embodiment is a radio receiver mounted on an automobile or a portable radio receiver which is movable. The radio broadcasting receiver 1 receives digital radio broadcasting based on a broadcasting standard of digital audio broadcasting (DAB) or analog radio broadcasting, such as FM radio broadcasting, from a radio broadcasting station 2. Furthermore, the radio broadcasting receiver 1 is connected to a wide area network (WAN) 3, such as the Internet, through mobile communication so as to receive IP radio broadcasting from an IP radio server 4 on the WAN 3. Here, the IP radio broadcasting performed by the IP radio server 4 includes IP radio broadcasting having the relationship of simultaneous broadcasting with digital radio broadcasting or analog radio broadcasting, that is, IP radio broadcasting having the same content as digital radio broadcasting or analog radio broadcasting. Note that, in this embodiment, sound received from the IP radio broadcasting having the relationship of the simultaneous broadcasting with digital radio broadcasting or analog radio broadcasting delays relative to sound broadcasted by the digital radio broadcasting or the analog radio broadcasting having the relationship of the simultaneous broadcasting with the IP radio broadcasting.
Next, a configuration of the radio broadcasting receiver 1 will be described with reference to Fig. 2.
As illustrated in Fig. 2, the radio broadcasting receiver 1 includes a digital radio tuner 101 which receives digital radio broadcasting and outputs received audio data, an analog radio tuner 102 which receives analog radio broadcasting, converts sound received from the analog radio broadcasting into digital sound, and outputs the sound as audio data, and an IP radio player 103 which receives IP radio broadcasting and outputs received audio data.
Here, the IP radio player 103 is connected to an IP server on the WAN 3 through a mobile communication device 104 which performs mobile communication, receives an audio stream delivered from the IP server through IP radio broadcasting, and reproduces/outputs audio data. Note that the radio broadcasting receiver 1 may include, instead of the mobile communication device 104, an external interface 105 to which a mobile phone 5 which performs mobile communication is connected. In this case, the IP radio player 103 may be connected to the IP server on the WAN 3 through the mobile communication performed by the mobile phone 5, receive an audio stream delivered by the IP server through IP radio broadcasting, and reproduce/output audio data.
The radio broadcasting receiver 1 further includes an input device 106, a display device 107, and a controller 108.
The radio broadcasting receiver 1 further includes a delay unit 109 which delays audio data to be output from the digital radio tuner 101 or the analog radio tuner 102 by a set delay target time before outputting the audio data, a selector 110 which selects and outputs one of audio data output from the delay unit 109 and audio data output from the IP radio player 103, a DA converter 111 which converts the audio data output from the selector 110 into an analog sound signal and outputs the analog sound signal, an amplifier 112 which amplifies the analog sound signal output from the DA converter 111, and a speaker 113 which is driven by the sound signal amplified by the amplifier 112 and which outputs sound.
The radio broadcasting receiver 1 further includes a sound type determination unit 114, a tuner memory 115, a player memory 116, and a comparator 117.
With this configuration, when receiving an instruction for receiving radio broadcasting of the specific radio broadcasting station 2 from a user through the input device 106, the controller 108 uses the digital radio tuner 101 as a current tuner if the radio broadcasting station 2 which is a source of the radio broadcasting broadcasts digital radio and uses the analog radio tuner 102 if the radio broadcasting station 2 which is the source of the radio broadcasting broadcasts analog radio so as to cause the current tuner to start reception of the radio broadcasting of the radio broadcasting station 2 which is instructed to be received by the current radio tuner and output of received audio data. Furthermore, the controller 108 clears content of storage of the tuner memory 115 and the player memory 116, sets 0 to the delay unit 109 as the delay target time, and causes the delay unit 109 to output the audio data supplied from the current tuner to the selector 110 as it is. Then the controller 108 causes the selector 110 to output the audio data supplied from the delay unit 109 to the DA converter 111 so that the sound supplied from the radio broadcasting station 2 which is instructed by the user to be received by the current tuner is output from the speaker 113.
On the other hand, the audio data output from the current tuner is also stored in the tuner memory 115. Here, the storage in the tuner memory 115 is performed such that the latest audio data for a predetermined reproduction time is stored in the tuner memory 115 at all time. Furthermore, a reproduction time of the audio data stored in the tuner memory 115 at all time is set to be equal to or longer than a period of time expected as a largest value of a delay time of the IP radio broadcasting having the relationship of simultaneous broadcasting with the digital/analog broadcasting relative to the digital/analog broadcasting.
Here, the delay unit 109 may delay the audio data by a delay process based on a delay process algorithm selected from among two delay process algorithms, that is, resampling and blank stretch. Then the delay unit 109 delays the audio data supplied from the current tuner by the delay target time set by the controller 108 by the delay process based on the delay process algorithm set by the controller 108 before outputting the audio data.
Here, the resampling is the following process. That is, as illustrated in Fig. 3A, audio data before delay is converted into audio data representing sound obtained by entirely expanding sound represented by the audio data before delay in a time axis direction (sound obtained by reducing a reproduction speed of the audio data before delay) and is output as audio data after delay. In this way, the delay of the audio data is gradually increased so that a delay time of the audio data reaches the delay target time set by the controller 108. When the delay of the audio data reaches the delay target time set by the controller 108, the audio data after delay is output while the delay time is maintained. Note that a rate of the expansion of the sound represented by the audio data in the resampling in the time axis direction is fixed (for example, a rate of increase of 10%) in this embodiment.
Furthermore, the blank stretch is a process described as follows. That is, as illustrated in Fig. 3B, only a blank section (a period of time recognized by a listener as silence) included in the audio data before delay is expanded in a time axis direction so that delay of the audio data is expanded such that a delay time of the audio data reaches the delay target time set by the controller 108. When the delay of the audio data reaches the delay target time set by the controller 108, the audio data after delay is output while the delay time is maintained. Note that a rate of the expansion of the blank section in the blank stretch in the time axis direction is fixed (for example, a rate of increase of 100%) in this embodiment.
Here, the delay process by the resampling includes a change of a pitch of sound although the delay is reliably increased, and therefore, a degree of the expansion in the time axis direction may not be increased. Accordingly, a comparatively long period of time is required until the delay time of the audio data is increased to reach the delay target time set by the controller 108.
On the other hand, in the delay process by the blank stretch, a large degree of the expansion of the blank sections in the time axis direction may be set since deterioration of sound in a non-blank section is not recognized by a listener. Therefore, in a case where a large amount of bland periods are included in the audio data before delay, the delay time of the audio data may rapidly reach the delay target time set by the controller 108. On the other hand, in a case where a small amount of blank sections is included in the audio data before delay, such as a case where the audio data before delay is music audio data, a longer period of time is required until the delay time of the audio data reaches the delay target time set by the controller 108 when compared with the delay process by the resampling.
Subsequently, the controller 108 performs a process of seamlessly performing switching of sound to be output to the speaker 113 between the sound received from the radio broadcasting being received and the sound received from the IP radio broadcasting having the relationship of simultaneous broadcasting with the radio broadcasting being received.
Hereinafter, the seamless switching process performed by the controller 108 for such seamless switching will be described.
Fig. 4 is a flowchart illustrating a procedure of the seamless switching process. Note that the seamless switching process is activated when an instruction for receiving the radio broadcasting from the specific radio broadcasting station 2 is issued by the user.
As illustrated in Fig. 4, in this process, a state in which the radio broadcasting receiver 1 outputs the sound of the radio broadcasting being received by the current tuner which is output from the delay unit 109 from the speaker 113 is waited (step 402). Thereafter, when the state in which the sound of the radio broadcasting is output from the speaker 113 is entered, deterioration of reception quality of the radio broadcasting being received by the current tuner is monitored (step 404). Here, obtainment of the reception quality of the radio broadcasting being received by the current tuner may be performed by calculating the reception quality of the radio broadcasting being received by the digital radio tuner 101 or the analog radio tuner 102 serving as the current tuner in accordance with reception electric field strength of the radio broadcasting being received, an SN ratio, an error generation rate, or the like and by obtaining the reception quality calculated by the current tuner using the controller 108.
Subsequently, if the reception quality of the radio broadcasting being received is deteriorated, start of reception of the IP radio broadcasting having the relationship of the simultaneous broadcasting with the radio broadcasting being received by the IP radio player 103 is controlled (step 406).
Thereafter, when the reception of the IP radio broadcasting by the IP radio player 103 is started, (step 408), a delay time of sound received from the IP radio broadcasting and a sound type of the radio broadcasting being received by the current tuner are calculated (step 410).
Here, the calculation of the delay time is performed as follows, for example.
Specifically, the controller 108 stores audio data for a predetermined reproduction time which is first received from the IP radio broadcasting output from the IP radio player 103 in the player memory 116.
Furthermore, the controller 108 causes the comparator 117 to compare the audio data stored in the player memory 116 with the audio data stored in the tuner memory 115 so as to search the audio data stored in the tuner memory 115 for a portion having an audio pattern which matches that of the audio data stored in the player memory 116.
Thereafter, the controller 108 calculates a difference between a reception time point of the audio data stored in the player memory 116 and a reception time point of the portion of the audio data stored in the tuner memory 115 as a delay time. Note that the reception time point of the searched portion of the audio data stored in the tuner memory 115 may be obtained in accordance with a position of the searched portion in a continuum of the audio data stored in the tuner memory 115.
Furthermore, the calculation of the sound type is performed by causing the sound type determination unit 114 to calculate a temporal rate of blank sections included in the audio data output from the current tuner in parallel to the calculation of the delay time described above, and determining that the sound type is large blank section sound when the rate of the blank sections is larger than a predetermined threshold value Th whereas determining that the sound type is small blank section sound when the rate of the blank sections is not larger than the threshold value Th.
Here, assuming that delay efficiency is a rate of an increased amount of delay in a period to the period, a temporal rate of blank sections which attains improved delay efficiency when the blank stretch is performed as the delay process rather than a case where the resampling is performed as the delay process or a value obtained by adding a certain margin to the temporal rate which attains improved delay efficiency is used as the predetermined threshold value Th.
However, the determination of the sound type may be performed by the sound type determination unit 114 at all time, and the calculation of the sound type performed in step 410 may be replaced by a process of obtaining a sound type of the radio broadcasting being received by the current tuner from the audio type determination unit 114 performed by the controller 108.
Alternatively, the determination of the sound type in step 410 may be replaced by a process of determining a sound type using information indicating a type of a program being broadcasted included in the radio broadcasting being received by the current tuner as control/additional information. Specifically, when the determined type of the program being received by the current tuner is music, the sound type may be determined as the small blank section sound, whereas when the determined type of the program being received by the current tuner is not music but a talk program, news, or the like, the sound type may be determined as the large blank section sound. Note that the control/addition information of the radio broadcasting which may be used for the determination of the sound type includes PTY and the like in the radio broadcasting of RDS or DAB.
Note that, instead of the determination of the sound type using the information indicating the type of the program being broadcasted included in the radio broadcasting as the control/additional information as described above, the sound type may be determined in accordance with a type of a program being received by the current tuner indicated by program listing separately obtained.
Thereafter, a delay process algorithm is set to the delay unit 109 in accordance with the sound type calculated in step 410 (step 412). In step 412, when the sound type determined in step 410 is the large blank section sound, the blank stretch is set to the delay unit 109 as the delay process algorithm whereas when the sound type calculated in step 410 is the small blank section sound, the resampling is set to the delay unit 109 as the delay process algorithm.
Furthermore, a delay time determined in step 410 is set to the delay unit 109 as the delay target time (step 414).
Here, the delay unit 109 to which a delay process algorithm and the delay target time are set as described above executes the delay process as described above in accordance with the set delay process algorithm so that the delay of the audio data input from the current tuner is expanded such that the set delay target time matches the delay time of the audio data output from the delay unit 109. After the set delay target time matches the delay time of the audio data output from the delay unit 109, the delayed audio data is output while the delay time is maintained.
Furthermore, when the set delay target time matches the delay time of the audio data output from the delay unit 109, the delay unit 109 notifies the controller 108 of the matching of the delay times.
On the other hand, when the delay time set in step 414 (the delay target time) matches the delay time of the audio data output from the delay unit 109 and the notification on the matching of the delay times is supplied from the delay unit 109 (step 416), the controller 108 controls the selector 110 so as to switch sound to be output to the speaker 113 to the sound received by the IP radio player 103 from the IP radio broadcasting (step 418). At this time, since the delay unit 109 is in a state in which the audio data received from the radio broadcasting is output in a delayed manner by the delay time of the audio data received from the IP radio broadcasting relative to the audio data received from the radio broadcasting, the audio data to be output from the speaker 113 is seamlessly switched from the audio data received from the radio broadcasting to the audio data output from the IP radio player 103 by the switching of the audio data output from the selector 110.
Thereafter, when output of the sound received by the IP radio player 103 through the IP radio broadcasting from the speaker 113 is started, recovery of reception quality of the radio broadcasting being received by the current tuner to preferred reception quality is monitored (step 420). When the reception quality is recovered to the preferred reception quality, the selector 110 switches the audio data to be output to the DA converter 111 to the audio data output from the delay unit 109. In this way, the sound to be output to the speaker 113 is switched to the sound of the radio broadcasting being received by the current tuner (step 422). At this time, since the delay unit 109 is in a state in which the audio data received from the radio broadcasting is output in a delayed manner by the delay time of the audio data received from the IP radio broadcasting relative to the audio data received from the radio broadcasting, the audio data to be output from the speaker 113 is seamlessly switched from the audio data output from the IP radio player 103 to the audio data received from the radio broadcasting by the switching of the audio data output from the selector 110.
Then the IP radio player 103 stops the reception of the IP radio broadcasting (step 424), and the process returns to step 404. Here, the IP radio player 103 disconnects the mobile communication of the mobile communication device 104 or the mobile phone 5 when stopping the reception of the IP radio broadcasting.
The seamless switching process performed by the controller 108 is described hereinabove.
Note that the seamless switching process described above is terminated when an instruction for terminating the reception of the radio broadcasting is issued by the user. Furthermore, the seamless switching process described above is reactivated when an instruction for receiving the radio broadcasting is newly issued by the user.
Hereinafter, an operation of the seamless switching process described above is illustrated.
Fig. 5 is a diagram illustrating a first operation of the seamless switching process.
It is assumed here that, in Fig. 5, rectangles surrounding numbers indicate audio data for unit time of a predetermined duration, rectangles surrounding numbers without "'" indicate audio data received by the current tuner from the radio broadcasting (digital radio broadcasting or analog radio broadcasting), rectangles surrounding numbers with "'" indicate audio data received by the IP radio player 103 from the IP radio broadcasting. Furthermore, rectangles having the same numbers (for example, "4" and "4'") indicate audio data having the same content.
Assuming that 0 is set as the delay target time to the delay unit 109 at a time point T0, the selector 110 is set so as to output audio data output from the delay unit 109 to the DA converter 111 in a period of time from the time point T0 to a time point T1 in which the current tuner receives the radio broadcasting with preferred reception quality. In this state, audio data (0 and 1) received by the current tuner from the radio broadcasting is output from the speaker 113 through the selector 110, the DA converter 111, and the amplifier 112 without being delayed by the delay unit 109.
If deterioration of the reception quality of the radio broadcasting is detected at the time point T1 in this state, the IP radio player 103 starts an operation of receiving the IP radio broadcasting.
Thereafter, in a period of time from the time point T1 to a time point T2, a sound type of the audio data received by the current tuner from the radio broadcasting is determined in accordance with a calculation of a temporal rate of blank sections performed by the sound type determination unit 114, and in addition, a delay time of the audio data received from the IP radio broadcasting relative to the audio data received by the current tuner from the radio broadcasting is calculated in accordance with a comparison performed by the comparator 117.
It is assumed here that blank sections in the audio data received by the current tuner from the radio broadcasting are small, and therefore, the small blank section sound is determined as a sound type. Furthermore, in the example of Fig. 5, 2 unit times is calculated as the delay time. On the other hand, even in the period of time from the time point T1 to the time point T2, audio data (2 to 5) received by the current tuner from the radio broadcasting is continuously output from the speaker 113 through the selector 110, the DA converter 111, and the amplifier 112 without being delayed by the delay unit 109.
Thereafter, at the time point T2, the resampling corresponding to the determined small blank section sound and the 2 unit times which is the calculated delay time are set to the delay unit 109 as the delay process algorithm and the delay target time, respectively. Since the set delay target time is larger than the delay time 0 at this time point, the delay unit 109 starts an operation of expanding the audio data supplied from the current tuner by the delay process of the resampling in the time axis direction and outputting the expanded audio data. Thereafter, audio data (6 to 9) expanded in the time axis direction is successively output from the speaker 113 through the selector 110, the DA converter 111, and the amplifier 112.
Subsequently, when the delay time of the audio data output from the delay unit 109 relative to the audio data input to the delay unit 109 matches the set delay target time at a time point T3 in which the output of the audio data (9) expanded in the time axis direction is completed, the audio data output from the selector 110 to the DA converter 111 is switched from the audio data output from the delay unit 109 to the audio data output from the IP radio player 103. As a result, the audio data output from the speaker 113 is switched from the sound received from the digital radio broadcasting or the analog radio broadcasting to the sound received from the IP radio broadcasting. Furthermore, audio data (9') output from the IP radio player 103 at the time point T3 is switched to audio data (10' to 13') output from the IP radio player 103 to be output from the speaker 113 through the selector 110, the DA converter 111, and the amplifier 112.
Here, at the time point T3, since the delay unit 109 is in a state in which the audio data received from the radio broadcasting is output in a delayed manner by the delay time of the audio data received from the IP radio broadcasting relative to the audio data received from the radio broadcasting, the audio data output from the speaker 113 is seamlessly switched from the audio data received from the radio broadcasting to the audio data output from the IP radio player 103.
Furthermore, the delay unit 109 stops the expansion of the audio data in the time axis direction at the time point T3 in which the output of the audio data (9) expanded in the time axis direction is completed, and after the time point T3, the delay unit 109 outputs audio data (10 to 15) received by the current tuner from the radio broadcasting without expansion in the time axis direction.
Subsequently, when reception quality of the current tuner is recovered to preferred reception quality at a time point T4 in which the output of audio data (10' to 13') from the IP radio player 103 to the speaker 113 is completed, audio data output from the selector 110 to the DA converter 111 is switched from the audio data output from the IP radio player 103 to the audio data output from the delay unit 109. Then, after the time point T4, audio data (14 and so on) delayed by the delay unit 109 by the delay time of the audio data received from the IP radio broadcasting relative to the audio data received by the current tuner from the radio broadcasting is output from the speaker 113 through the selector 110, the DA converter 111, and the amplifier 112.
At the time point T4, since the delay unit 109 is in a state in which the audio data received from the radio broadcasting is output in a delayed manner by the delay time of the audio data received from the IP radio broadcasting relative to the audio data received from the radio broadcasting, the audio data to be output from the speaker 113 is seamlessly switched from the audio data output from the IP radio player 103 to the audio data received from the radio broadcasting.
Fig. 6 is a diagram illustrating a second operation of the seamless switching process.
As with the case of Fig. 5, assuming that 0 is set as the delay target time to the delay unit 109 at a time point T0, the selector 110 is set so as to output the audio data output from the delay unit 109 to the DA converter 111 in a period of time from the time point T0 to a time point T1 in which the current tuner receives the radio broadcasting with preferred reception quality. In this state, audio data (0 and 1) received by the current tuner from the radio broadcasting is output from the speaker 113 through the selector 110, the DA converter 111, and the amplifier 112 without being delayed by the delay unit 109.
If deterioration of the reception quality of the radio broadcasting is detected at the time point T1 in this state, the IP radio player 103 starts an operation of receiving the IP radio broadcasting.
Thereafter, in a period of time from the time point T1 to a time point T2, a sound type of the audio data received by the current tuner from the radio broadcasting is determined in accordance with a calculation of a temporal rate of blank sections performed by the sound type determination unit 114, and in addition, a delay time of the audio data received from the IP radio broadcasting relative to the audio data received by the current tuner from the radio broadcasting is calculated in accordance with a comparison performed by the comparator 117.
It is assumed here that an amount of blank sections in the audio data received by the current tuner from the radio broadcasting is large, and therefore, the large blank section sound is determined as the sound type. Furthermore, in the example of Fig. 6, 2 unit times is calculated as the delay time. On the other hand, even in the period of time from the time point T1 to the time point T2, audio data (2 to 5) received by the current tuner from the radio broadcasting is continuously output from the speaker 113 through the selector 110, the DA converter 111, and the amplifier 112 without being delayed by the delay unit 109.
Thereafter, at the time point T2, the blank stretch corresponding to the calculated large blank section sound and the 2 unit times which is the calculated delay time are set to the delay unit 109 as the delay process algorithm and the delay target time, respectively. Since the set delay target time is larger than the delay time 0 at this time point, the delay unit 109 starts an operation of expanding only the blank sections of the audio data supplied from the current tuner by the delay process of the blank stretch in the time axis direction and outputting the audio data. Here, the example of Fig. 6 illustrates a case where audio data 7 and audio data 9 correspond to a blank section among audio data (6 to 9), and in this case, only the audio data 7 and the audio data 9 are expanded in the time axis direction when being output.
Accordingly, the audio data 6 in a sound section which is not expanded in the time axis direction, the audio data 7 in the blank section which is expanded in the time axis direction, the audio data 8 in the sound section which is not expanded in the time axis direction, and the audio data 9 in the blank section which is expanded in the time axis direction are successively output from the speaker 113 through the selector 110, the DA converter 111, and the amplifier 112.
Subsequently, when the delay time of the audio data output from the delay unit 109 relative to the audio data input to the delay unit 109 matches the set delay target time at a time point T3 in which the output of the audio data (9) expanded in the time axis direction is completed, audio data to be output from the selector 110 to the DA converter 111 is switched from the audio data output from the delay unit 109 to the audio data output from the IP radio player 103. As a result, the audio data to be output from the speaker 113 is switched from the sound received from the digital radio broadcasting or the analog radio broadcasting to the sound received from the IP radio broadcasting. Furthermore, audio data (10') output from the IP radio player 103 at the time point T3 is switched to audio data (10'-13') output from the IP radio player 103 to the speaker 113 through the selector 110, the DA converter 111, and the amplifier 112.
Here, at the time point T3, since the delay unit 109 is in a state in which the audio data received from the radio broadcasting is output in a delayed manner by the delay time of the audio data received from the IP radio broadcasting relative to the audio data received from the radio broadcasting, audio data to be output from the speaker 113 is seamlessly switched from the audio data received from the radio broadcasting to the audio data output from the IP radio player 103.
A subsequent operation is the same as the process illustrated in Fig. 5.
The embodiment of the present invention has been described hereinabove.
According to this embodiment, in a case where a rate of the blank sections of the sound of the radio broadcasting required to be delayed for seamless switching from the radio broadcasting to the IP radio broadcasting indicates sound of a level equal to or larger than a predetermined level, only the blank sections of the sound of the radio broadcasting is temporally expanded so that the sound of the radio broadcasting is delayed, and otherwise, the sound of the radio broadcasting is temporally expanded in a uniform manner so that the sound of the radio broadcasting is delayed. Accordingly, in a case where an amount of blank sections of the sound of the radio broadcasting is large, the sound may be rapidly delayed by the delay time of the IP radio broadcasting relative to the radio broadcasting, and even in a case where the amount of blank sections is small or a blank section is not included in the sound of the radio broadcasting, the sound may be reliably delayed within a certain period by the delay time of the IP radio broadcasting relative to the radio broadcasting.
Here, in the embodiment described above, the controller 108 may perform a seamless switching process illustrated in Fig. 7 instead of the seamless switching process illustrated in Fig. 4.
In the seamless switching process illustrated in Fig. 7, in step 414 of the seamless switching process illustrated in Fig. 4, after the delay time calculated in step 410 is set to the delay unit 109 as the delay target time, a state of the delay of the delay unit 109 is monitored until the matching of the delay times is informed from the delay unit 109 (step 416). Then, the delay process algorithm used by the delay unit 109 is changed in accordance with the delay state.
Specifically, as illustrated in Fig. 7, when setting the delay time calculated in step 410 to the delay unit 109 as the delay target time (step 414), the controller 108 determines whether the delay process algorithm set in the delay unit 109 is the blank stretch and delay efficiency is smaller than the threshold value Th1 (step 702) and determines whether the delay process algorithm set in the delay unit 109 is the resampling and a temporal rate of the blank sections in the audio data before delay is larger than a threshold value Th2 (step 704).
Note that, as the threshold value Th1, a value equal to the delay efficiency obtained in the case where the resampling is performed as the delay process or a value obtained by reducing a certain margin from the delay efficiency obtained in the case where the resampling is performed is used. As the threshold value Th2, a temporal rate of blank sections which attains improved delay efficiency when the blank stretch is performed as the delay process rather than a case where the resampling is performed as the delay process or a value obtained by adding a certain margin to the temporal rate of the blank sections which attains improved delay efficiency is used.
In the case where the delay process algorithm set in the delay unit 109 is the blank stretch and the delay efficiency is smaller than the threshold value Th1 (step 702), the resampling is newly set to the delay unit 109 as the delay process algorithm (step 706).
On the other hand, in the case where the delay process algorithm set in the delay unit 109 is the resampling and the temporal rate of the blank sections of the audio data before delay is larger than the threshold value Th2 (step 704), the blank stretch is newly set to the delay unit 109 as the delay process algorithm (step 708).
Fig. 8 is a diagram illustrating an operation of the seamless switching process illustrated in Fig. 7.
Assuming that 0 is set as the delay target time to the delay unit 109 at a time point T0, the selector 110 is set so as to output the audio data output from the delay unit 109 to the DA converter 111 in a period of time from the time point T0 to a time point T1 in which the current tuner receives the radio broadcasting with preferred reception quality. In this state, audio data (0 and 1) received by the current tuner from the radio broadcasting is output from the speaker 113 through the selector 110, the DA converter 111, and the amplifier 112 without being delayed by the delay unit 109.
If deterioration of the reception quality of the radio broadcasting is detected at the time point T1 in this state, the IP radio player 103 starts an operation of receiving the IP radio broadcasting.
Thereafter, in a period of time from the time point T1 to a time point T2, a sound type of the audio data received by the current tuner from the radio broadcasting is determined in accordance with a calculation of a temporal rate of blank sections performed by the sound type determination unit 114, and in addition, a delay time of the audio data received from the IP radio broadcasting relative to the audio data received by the current tuner from the radio broadcasting is calculated in accordance with a comparison performed by the comparator 117.
It is assumed here that an amount of blank sections in the audio data received by the current tuner from the radio broadcasting is large, and therefore, the sound type is determined to be the large blank section sound. Furthermore, in the example of Fig. 8, 2 unit times is calculated as the delay time. On the other hand, even in the period of time from the time point T1 to the time point T2, audio data (2 to 5) received by the current tuner from the radio broadcasting is continuously output from the speaker 113 through the selector 110, the DA converter 111, and the amplifier 112 without being delayed by the delay unit 109.
Thereafter, at the time point T2, the blank stretch corresponding to the determined large blank section sound and the 2 unit times which is the calculated delay time are set to the delay unit 109 as the delay process algorithm and the delay target time, respectively. Since the set delay target time is larger than the delay time 0 at this time point, the delay unit 109 starts an operation of expanding only blank sections of the audio data supplied from the current tuner by the delay process of the blank stretch in the time axis direction and outputting the audio data. The example of Fig. 8 indicates a case where audio data (6 to 8) corresponds to a sound section. In this case, the audio data (6 to 8) is not expanded in the time axis direction before being output and a delay of the audio data remains as a delay time of 0.
Thereafter, if it is determined that delay efficiency in a period in which the audio data (6 to 8) is output is smaller than the threshold value Th1 at a time point Tc in which output of the audio data 8 is completed, the controller 108 newly sets the resampling to the delay unit 109 as the delay process algorithm.
By this, after the time point Tc, the delay unit 109 starts an operation of expanding the audio data supplied from the current tuner by the delay process of the resampling in the time axis direction and outputting the audio data. Thereafter, the audio data (9 to 12) expanded in the time axis direction is successively output from the speaker 113 through the selector 110, the DA converter 111, and the amplifier 112.
Subsequently, when the delay time of the audio data output from the delay unit 109 relative to the audio data input to the delay unit 109 matches the set delay target time at a time point T3 in which the output of the audio data (12) expanded in the time axis direction is completed, audio data to be output from the selector 110 to the DA converter 111 is switched from the audio data output from the delay unit 109 to the audio data output from the IP radio player 103. As a result, audio data output from the speaker 113 is switched from the sound received from the digital radio broadcasting or the analog radio broadcasting to the sound received from the IP radio broadcasting. Furthermore, audio data (12') output from the IP radio player 103 at the time point T3 is switched to audio data (13' and so on) output from the IP radio player 103 to the speaker 113 through the selector 110, the DA converter 111, and the amplifier 112.
Here, at the time point T3, since the delay unit 109 is in a state in which the audio data received from the radio broadcasting is output in a delayed manner by the delay time of the audio data received from the IP radio broadcasting relative to the audio data received from the radio broadcasting, audio data output from the speaker 113 is seamlessly switched from the audio data received from the radio broadcasting to the audio data output from the IP radio player 103.
As illustrated in the processing example, according to the seamless switching process illustrated in Fig. 7, even in a case where an amount of blank sections in the sound of the radio broadcasting is changed after the delay unit 109 starts the delay of the sound of the radio broadcasting, the seamless switching from the radio broadcasting to the IP radio broadcasting may be rapidly completed.
Although the blank stretch and the resampling are used as the delay process algorithm in the foregoing embodiment, an arbitrary delay process algorithm, such as time stretch which does not change a pitch, may be used as long as audio data is entirely expanded in a uniform manner in a time axis direction. Note that, irrespective of the algorithm for entirely expanding audio data in a uniform manner in a time axis direction, increase of deterioration of sound quality or deterioration of reproducibility may not be avoided when a degree of expansion in the time axis direction is increased, and therefore, the degree of expansion in the time axis direction may not be considerably increased. Accordingly, the delay unit 109 requires a long period of time to expand the audio data so that the delay of the audio data reaches the delay time set by the controller 108.
Furthermore, the radio receiver according to the embodiment described above may include, instead of the IP radio player 103, a receiver which receives broadcasting which uses an arbitrary broadcasting method and an arbitrary broadcasting medium and which has the relationship of the simultaneous broadcasting with the digital radio broadcasting or the analog radio broadcasting. Also in this case, as with the audio data output from the IP radio player 103, audio data output from the receiver included in the radio receiver instead of the IP radio player 103 is processed.

Claims

A radio receiver capable of receiving radio broadcasting and parallel broadcasting in which sound having the same content as the radio broadcasting is transmitted after being delayed relative to the radio broadcasting, the radio receiver comprising:
an output unit (113) configured to output sound to a user;

a radio receiving unit (101, 102) configured to receive the radio broadcasting and output received sound to the output unit;

a parallel broadcasting receiving unit (103) configured to receive the parallel broadcasting and output received sound to the output unit;

a delay unit (109) configured to delay the sound output by the radio receiving unit to the output unit;

a sound type determination unit (114) configured to determine whether sound being received by the radio receiving unit is large blank section sound having a rate of blank sections equal to or larger than a predetermined level or determine whether sound received by the radio receiving unit is small blank section sound having a rate of blank sections which is not equal to or larger than the predetermined level; and

a controller (108) configured to control switching of sound to be output to the user from the sound received by the radio receiving unit to the sound received by the parallel broadcasting receiving unit,
wherein the output unit is configured to selectively output to the user one of the sound output from the radio receiving unit and the sound output from the parallel broadcasting receiving unit under control of the controller,
the delay unit is configured to perform, under control of the controller,
a blank section expansion delay operation of increasing the delay of the sound by temporary expanding only the blank sections of the sound output from the radio receiving unit, and

an entire expansion delay operation of increasing the delay of the sound by temporally expanding the sound output from the radio receiving unit in a uniform manner, and
the controller
is configured to cause the delay unit to perform the blank section expansion delay operation in a case where the sound type determination unit determines that the sound received by the radio receiving unit is the large blank section sound, and is configured to cause the delay unit to perform the entire expansion delay operation in a case where the sound type determination unit determines that the sound received by the radio receiving unit is the small blank section sound, and

to cause the output unit to switch the sound to be output to the user from the sound output from the radio receiving unit to the sound output from the parallel broadcasting receiving unit if a delay time of the delay of the sound output from the radio receiving unit matches a delay time of the sound received by the parallel broadcasting receiving unit relative to the sound received by the radio receiving unit.
The radio receiver according to claim 1, wherein the controller is configured to control the delay unit such that the blank section expansion delay operation is stopped and the entire expansion delay operation is performed when an increase rate of the delay time of the delay of the sound output from the radio receiving unit by the delay unit becomes equal to or smaller than a predetermined level during a period in which the delay unit performs the blank section expansion delay operation.
The radio receiver according to claim 1 or claim 2, wherein the controller is configured to control the delay unit so that the delay unit stops the entire expansion delay operation and performs the blank section expansion delay operation when a rate of the blank sections of the sound received by the radio receiving unit becomes equal to or larger than a predetermined threshold value in a period of time in which the delay unit performs the entire expansion delay operation.
The radio receiver according to any one of claim 1 to claim 3, wherein the entire expansion delay operation increases delay of the sound output from the radio receiving unit by converting the sound into sound of a lower reproduction speed.
The radio receiver according to any one of claim 1 to claim 3, wherein time stretch is performed on the sound output from the radio receiving unit without changing a pitch in the entire expansion delay operation.
The radio receiver according to any one of claim 1 to claim 5, wherein the sound type determination unit is configured to identify a type of a program received by the radio receiving unit, to determine that sound received by the radio receiving unit is the small blank section sound in a case where at least the identified type of the program is a music program, and to determine that the sound received by the radio receiving unit is the large blank section sound in a case where the identified type of the program is news.
The radio receiver according to any one of claim 1 to claim 6,
wherein the parallel broadcasting is IP radio broadcasting, and
the parallel broadcasting receiving unit is an IP radio player which receives the IP radio broadcasting and outputs received sound.
The radio receiver according to any one of claim 1 to claim 7, wherein the radio broadcasting is at least one of digital radio broadcasting and analog radio broadcasting.
The radio receiver according to any one of claim 1 to claim 8, wherein the radio receiver is an in-vehicle radio receiver installed in a vehicle.