JPWO2009057639A1 - Digital broadcast receiver - Google Patents

Abstract

A digital broadcast receiving device (100) of a digital broadcast system that broadcasts the same service at a plurality of physical frequencies includes a storage unit (120) that stores information indicating a plurality of physical frequencies that broadcast the same service, and a digital Based on the acquired PMT, the acquisition unit (130) that acquires the PMT from the broadcast, the reception unit (110) that receives the data of the desired service from the digital broadcast, and switched during reception of the digital broadcast service, When it is determined that a service broadcast on a physical frequency different from the physical frequency on which the service being received is broadcast is the same service as the service being received based on the information stored in the storage unit (120) The receiving unit (110) uses the PMT of the receiving service acquired by the acquiring unit (130) to receive data of the same service as the receiving service broadcast on another physical frequency. Control And a control unit (140).

Description

Cross-reference to related applications

  This application claims the benefit of priority from Japanese Patent Application No. 2007-282335 (filed on Oct. 30, 2007), the entire contents of which are incorporated herein by reference.

  The present invention relates to a broadcast receiving apparatus that receives digital terrestrial broadcasting and displays video / audio content.

  Digital terrestrial television broadcasting operated in Japan is called ISDB-T (Integrated Services Digital Broadcasting for Terrestrial), and employs OFDM (Orthogonal Frequency Division Multiplexing) modulation. This ISDBT system divides the transmission band of one channel into 13 segments, and 1 segment (central segment number 0) is used for mobile terminals such as mobile phones and PDAs (Personal Digital Assistants). It is assigned to terrestrial digital broadcasting, so-called 1-segment broadcasting (partial reception layer).

  In digital terrestrial broadcasting, video data, audio data, and the like are each divided into packets called 188-byte transport stream packets (TSP: Transport Stream Packets). They are multiplexed in a time division manner in the MPEG2-TS (Transport Stream) format, and are broadcast together as a transport stream (TS). FIG. 11 is a schematic diagram illustrating TS. Video data and audio data are each divided into 188-byte TSPs, multiplexed, and broadcast as TS. Individual identification information called PID (Packet ID) is assigned to the 4-byte header of each TSP for each data type and service, and by this PID, which service video data or audio data the TSP is. Can be determined.

  In MPEG2-TS, not only video data and audio data but also subtitle data and data broadcast, PCR (Program Clock Reference) which is a reference of video and audio time, program arrangement information SI (Service Information) of broadcasting service, and the like. Multiplexed. Among information related to these broadcasting services, information necessary for acquiring a desired service (program) from MPEG2-TS includes PAT (Program Association Table) and PMT (Program Map Table). ) Information.

  Here, the relationship between PAT and PMT will be described. The PMT is a table for specifying the PID of the TSP that transmits the video, audio, data, and other streams constituting the service, and exists for each service. On the receiving side, the TSP having the PID described in the PMT corresponding to the desired program is received and the program is reproduced. The PMT of each program is multiplexed on the TS, and the PID of the multiplexed PMT is stored in the PAT. Therefore, when receiving a PMT of a program, it is necessary to receive a PAT storing the PID of the PMT in advance. The PID of the PAT is defined in advance, and is, for example, “0x0000” in ARIB (Association of Radio Industries And Businesses). In 1-segment broadcasting, the PAT is not used, and the value of the lower 3 bits of the service ID included in the NIT (Network Information Table: network information management table) in which the PID is defined in advance as “0x10” PMT PID is allocated. For example, when the lower 3 bits of the service ID are 0, the PID of the PMT is “0x1FC8”, and when it is 1, it is “0x1FC9”. These PAT, PMT, and NIT are shown in FIGS. In the figure, the portions highlighted by hatching are portions particularly used in the present invention, and will be described later.

  In digital broadcasting, information such as PCR (Program Clock Reference) and PTS (Presentation Time Stamp) is used for synchronous reproduction of video and audio. The PCR includes information related to the reference time transmitted for each service, and the receiving device receives the PCR and adjusts its own clock to the reference time. The PTS is a time stamp indicating the playback time (display time) of video and audio. Therefore, the receiving apparatus buffers the received video and audio data, and when the time related to the buffered data specified by the PTS matches the clock of the own apparatus that has received and adjusted the PCR, And playing audio.

  In addition, when a user is receiving a 1-segment broadcast with a mobile terminal, the mobile terminal is often carried around due to its nature, and there is often an opportunity to cross a broadcasting district. For example, a user who commutes or goes to a city from the suburbs often has a broadcast area in which his home and work / school are different. In digital broadcasting, the channel (that is, frequency) of a broadcasting station differs depending on the district, and the same program is broadcast at different frequencies. Therefore, there is a case where the same service is provided in a channel to which a user switches over different broadcast areas.

  Recently, it has been proposed to retransmit broadcast waves using antennas or leaky cables in areas or places where radio waves from broadcast stations are difficult to reach (referred to as gap fillers). This re-transmission employs the above-mentioned ISDB-T system, receives digital broadcast waves from a plurality of broadcast stations, extracts 1-segment broadcasts, and connects them to a predetermined channel different from the above-mentioned broadcast station channel. Retransmit on the channel. That is, the same service as the service (program) broadcasted by the broadcast station is broadcast using a frequency different from that used by the broadcast station. Further, in CS digital broadcasting, the same service as terrestrial digital broadcasting is broadcast on a different frequency (that is, a different channel). In IPTV, the same service as terrestrial digital broadcasting is broadcast over a network on an IP basis.

  For the same service, PAT and PMT, which are information related to PID for each service, are also the same. Therefore, the above-described gap filler or IPTV broadcasts TS including the same PAT and PMT at different physical frequencies or by a network system that does not use physical frequencies.

  By the way, the video content of 1-segment broadcasting is H.264. H.264 is encoded. H. In H.264, an IDR (Instantaneous Decoding Refresh) picture that can decode one picture as a group of video frames and a picture that is decoded after referring to another picture are decoded. There is a non-IDR picture that can be done. Therefore, when decoding from only non-IDR pictures, there is no picture to be referenced, and thus video cannot be displayed normally. Therefore, H.I. In order to decode video content encoded in H.264, it is necessary to decode from an IDR picture.

  Note that program arrangement information (SI: Service Information) such as NIT, PAT, and PMT, which is table information relating to each service, is not always transmitted, but is transmitted at certain intervals. Accordingly, it takes a certain amount of time to receive the program arrangement information of the broadcast service, and as a result, the information necessary for the channel selection operation for the desired service, that is, the reproduction of the service such as PAT, PMT, IDR picture, etc. is received. Thus, the processing as described above for outputting a desired service takes time. For example, Non-Patent Document 1 stipulates that the NIT retransmission period for a partial reception layer is 1 second (maximum 3 seconds) and the PMT retransmission period is 200 ms (maximum 500 ms). Further, in Non-Patent Document 2, the transmission cycle of an I picture (IDR picture) of a partial reception layer video (that is, the transmission cycle of a TSP including an IDR picture) is normally defined as 2 seconds and a maximum of 5 seconds. In other words, it takes 3.2 seconds at maximum from the channel selection to the output of video and audio, taking the normal operation of the partial reception layer as an example.

  As described above, conventionally, there is a problem that it takes time to select a channel from when a user selects a desired program until the user views the program. Therefore, there is a risk of causing the user to feel stress due to the inability to view the program smoothly. As a countermeasure to this problem, a method of outputting video and audio using the latest PMT at the time of tuning is disclosed in order to speed up the output of video and audio at the time of tuning (see Non-Patent Document 3). I want to be.) In addition, a method is disclosed in which a PMT is stored in association with each program, and the stored PMT is used at the time of the next channel selection to speed up the channel selection (see Non-Patent Document 4).

ARIB Standard TR-B14 2.3 Edition 4th Part 12.4 ARIB Standard TR-B14 2.3 Third Edition Part 4 Part 5.1 ARIB Standard TR-B14 2.3 Second Edition 6.3 JP-A-10-271464

  In the conventional digital broadcasting channel selection method, after the channel is switched, the data (PAT, PMT, etc.) received in the channel before switching is changed every time the channel is switched in order to prevent the output of video / audio of the channel before switching. And the time-based data and video / audio data received and buffered based on them are discarded. Therefore, even when the same service is broadcast on the switching destination channel, conventionally, the PAT and PMT are newly received again on the switching destination channel, and the TSP having the desired PID is received based on the PAT and PMT. Need to watch.

  However, if the video and audio are displayed after receiving the PAT and PMT again when selecting the same service with a different frequency or transmission method, the channel selection process (the video of the program after switching the channel is performed for the reason described above. Display and audio output) are slow. In addition, in ARIB, it is recommended to use the latest PMT received before, but it is assumed that the latest PMT is associated with a certain physical channel (for example, Patent Document 1 supports each program). ) Therefore, when the reception interval is empty and the latest PMT received previously is old without being updated, there is a possibility that a PID different from that of the currently broadcast video / audio is stored in the PMT. Yes and lacks reliability. Further, data (program content) received on the channel before switching can be used for displaying program video and outputting audio even when the channel is switched with the same service as the channel to which switching is performed. Nevertheless, the data (program content) received on the channel before switching is discarded without being used when the channel is switched, and is not used to deal with the delay in the channel selection process.

  Accordingly, an object of the present invention is to provide a technique (apparatus and method) that makes channel selection processing faster when switching to a channel that is broadcasting the same service as a channel being received in a digital broadcast receiving apparatus. It is in.

  In order to solve the above-described problems, a digital broadcast receiving apparatus according to the present invention is a digital broadcast receiving apparatus of a digital broadcast system that broadcasts the same service (program) at a plurality of physical frequencies. A storage unit that stores information indicating a plurality of physical frequencies to be broadcast (a table in which services and physical frequencies are associated), an acquisition unit that acquires a PMT (Program Map Table) from a digital broadcast (from PAT or NIT), Based on the PMT acquired by the acquisition unit, a reception unit that receives data (video / audio / text broadcast data) of a desired service from digital broadcasting, and (received by the PMT acquired by the acquisition unit and the reception unit) A buffer for storing data, and) during reception of a digital broadcast service, based on information stored in the storage unit, When the same service as the service being received is received by switching to another physical frequency different from the physical frequency at which the service is broadcast, the acquisition unit acquires (stored in the buffer) And a control unit that controls the receiving unit so as to receive data of the same service as the currently received service broadcast on the different physical frequency using the service PMT. And

  The digital broadcast receiving apparatus according to an embodiment of the present invention switches to a frequency different from a physical frequency for broadcasting the service being received, and receives the same service as the service being received, The control unit does not discard the data of the service being received (stored in the buffer) acquired by the acquisition unit, and is the same service as the service being received that is being broadcast on the different physical frequency It is characterized by using as data.

  Further, it is preferable that each of the physical frequencies is a physical channel. It is preferable that each of the physical frequencies is information indicating a physical channel and a segment.

  A digital broadcast receiving apparatus according to a further embodiment of the present invention is a digital broadcast receiving apparatus of a digital broadcast system that provides the same service (program) with a plurality of service identifiers via a network, and the same service. A storage unit for storing information (a table in which services and service identifiers are associated with each other) indicating a plurality of service identifiers (URLs, etc.) providing PMT, and acquiring a PMT (Program Map Table) from digital broadcasting (from PAT or NIT) A receiving unit that receives data (video / audio / text broadcast data) of a desired service from digital broadcasting based on the PMT acquired by the acquiring unit, and (the PMT acquired by the acquiring unit and the PMT A buffer for storing data received by the receiving unit, and) in the storage unit during reception of the digital broadcasting service When acquiring the same service as the currently received service by switching to another service identifier different from the service identifier that provides the currently received service based on the stored information, the acquisition unit acquires Using the PMT of the receiving service (stored in the buffer), the receiving so as to receive data of the same service as the receiving service being broadcast with the different service identifier And a control unit for controlling the unit.

  As described above, the solution of the present invention has been described as an apparatus. However, the present invention can be realized as a method, a program, and a storage medium that stores the program substantially corresponding to these, and the scope of the present invention. It should be understood that these are also included.

  For example, a control method of a digital broadcast receiving apparatus according to another embodiment, which realizes the present invention as a method, is a digital broadcast receiving apparatus of a digital broadcast system that broadcasts the same service (program) at a plurality of physical frequencies. A method of storing information indicating a plurality of physical frequencies that broadcast the same service (a table in which services and physical frequencies are associated); and a PMT (Program Map Table) (PAT or Acquiring from the NIT, receiving the desired service data (video / audio / text broadcast data) from the digital broadcast based on the PMT acquired by the acquiring unit, and the PMT acquired by the acquiring unit And storing the data received by the receiving unit)) during the reception of the digital broadcast service, the storage unit When acquiring the same service as the currently received service by switching to another physical frequency different from the physical frequency for broadcasting the currently received service based on the stored information, the acquisition unit acquires Using the PMT of the receiving service (stored in the buffer) to receive the content of the same service as the receiving service broadcast on the different physical frequency And a step of controlling the unit. It should be noted that arithmetic means (processors such as a CPU, DSP, MPU) can be used for calculation and processing of each step as necessary.

  According to the present invention, when switching to a channel that is broadcasting the same service as the channel being received, the channel selection processing (that is, provision of service content to the user) for the channel to be switched to is performed in a conventional manner. It is possible to perform faster than.

1 is a configuration diagram of a broadcasting system including a receiving device to which the present invention is applied and a broadcasting device that provides broadcast waves to the receiving device. It is a figure which shows the segment structure of the channel which the broadcast apparatus 300 transmits. It is a block diagram of the receiver by one embodiment of this invention. It is an example of the flowchart which shows the general normal channel selection process in the receiving terminal of 1 segment broadcasting. It is a flowchart of the reception process of the receiver 100 by this invention. It is a flowchart of the buffer duplication process of the reception process by this invention. It is a figure which shows a 1st channel table. It is a figure which shows a 2nd channel table. It is a figure which illustrates typically the time required until data are output. It is a flowchart which shows the reception process of the receiver by a prior art. It is the schematic of TS. It is the schematic of PAT. It is the schematic of PMT. It is the schematic of NIT.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Receiver 110 Receiving part 120 Storage part 130 Section analysis part 140 Control part 150 Memory 160 Decoding part 162 Video decoding part 164 Audio decoding part 166 Subtitle decoding part 170 Data broadcast processing part 180 Separation part 190 Audio output part 200,300,400 Broadcasting device ANT Antenna DIS Display part L1-L6 Channel table

  FIG. 1 is a configuration diagram of a broadcasting system including a receiving apparatus to which the present invention is applied and a broadcasting apparatus that provides broadcast waves to the receiving apparatus. As shown in the figure, this broadcasting system includes a receiving device 100 and broadcasting devices 200, 300, and 400. Broadcast apparatuses 200 and 400 are broadcast apparatuses of a general digital broadcast system. One segment broadcast (one segment broadcast), that is, digital broadcast using a segment for partial reception that can be received by one segment alone, and Digital broadcasting for terrestrial television using 12 segments. In this digital broadcasting system, the broadcasting device 200 and the broadcasting device 300 are broadcasting the same service, but the physical frequency band used by the broadcasting device 200 and the physical frequency band used by the broadcasting device 300 are the same. Is different. That is, all or part of the service broadcast from the broadcast device 200 is broadcast from the broadcast device 300 using a physical frequency band different from the physical frequency band used by the broadcast device 200. The receiving device 100 according to the present invention can receive a digital broadcast broadcast from the broadcasting device 200 in a reception area covered by the broadcasting device 200. For example, when the receiving apparatus 100 enters an underground mall or the like, the digital broadcast from the broadcasting apparatus 200 becomes a weak electric field or out of service area, and it is difficult to continue receiving. On the contrary, it may occur that the digital broadcast from the broadcasting device 300 goes out to the ground from the underground shopping street, becomes a weak electric field or out of service area, and it is difficult to continue reception. In such a case, the receiving device 100 seamlessly switches between receiving the digital broadcast of the broadcasting device 200 and receiving the digital broadcast of the broadcasting device 300 based on the channel table. Details of this will be described later.

  Alternatively, for example, the receiving apparatus 100 may be far away from the broadcasting apparatus 200 and the digital broadcast becomes a weak electric field or out of service area, making it difficult to continue receiving, and entering the area covered by the broadcasting apparatus 400 may occur. Even in such a case, the receiving apparatus 100 seamlessly switches between the digital broadcast reception of the broadcast apparatus 200 and the digital broadcast reception of the broadcast apparatus 400 via the regional channel table.

  FIG. 2 is a diagram illustrating a segment configuration of a channel transmitted by the broadcasting device 300. As shown in the upper part of the figure, the broadcasting apparatus 200 which is a normal broadcasting station uses the central segment number 0 for each physical channel for 1-segment broadcasting which is a segment for partial reception. Broadcast apparatus 300 broadcasts the services of segment number 0 for partial reception connected within one physical channel. It should be noted that the services (channels) do not have to be completely connected without a gap so that the lower segment 7 in FIG. 2 is unused.

  FIG. 3 is a block diagram of a broadcast receiving apparatus according to an embodiment of the present invention. As the broadcast receiving apparatus 100, a portable terminal, a PDA, or the like can be applied. In this embodiment, a description is given assuming a portable terminal capable of receiving 1-segment broadcasting. As shown in FIG. 3, the receiving apparatus 100 includes an antenna ANT, a receiving unit 110, a storage unit 120, a section analysis unit 130, a control unit 140, a memory 150, a decoding unit 160, a data broadcast processing unit 170, a separation unit 180, an audio. An output unit 190 and a display unit DIS are provided. The decoding unit 160 includes a video decoding unit 162, an audio decoding unit 164, and a caption decoding unit 166.

  A description will be given of the channel selection processing by the receiving apparatus 100 together with the description of the function of each component. Based on a channel selection instruction (channel designation command) from the user, the control unit 140 controls the reception unit 110 to receive an RF signal having a frequency of the designated channel. The receiving unit 110 receives control of the control unit 140 and receives an RF signal (broadcast wave) having a frequency of a designated channel by the antenna ANT. This RF signal is broadcast (transmitted) from, for example, broadcast (transmission) devices 200, 300, and 400. The receiving unit 110 further converts the frequency of the received RF signal and demodulates the frequency-converted signal to obtain MPEG2-TS. The separation unit 180 receives (acquires) the NIT multiplexed in the demodulated TS, acquires the service ID from the NIT, and obtains the PID of the PMT from the lower 3 bits of the service ID. Thereafter, the TSP having the PID described in the PMT is filtered to extract the TSP from the TS. That is, the separation unit 180 extracts a TSP that includes a section having video, audio, data broadcasting, and caption data, and program arrangement information (SI) that constitutes a service of a designated channel from the TS. Further, the separation unit 180 stores each extracted TSP in the memory (buffer) 150. The memory 150 can also be included in the storage unit 120.

  Each data extracted from the separation unit 180 is output to the video decoding unit 162, the audio decoding unit 164, the data broadcast processing unit 170, the caption decoding unit 166, and the section analysis unit 130, respectively. The audio decoding unit 164 decodes the TSP including the audio data and outputs the decoded audio to the audio output unit 190 (speaker or earphone). The video decoding unit 162 decodes the video data and outputs the decoded video content to the display unit DIS. The data broadcast processing unit 170 processes the data broadcast data into a screen display format, and outputs the data broadcast content to the display unit DIS. The data broadcast processing unit 170 also performs script processing included in the data broadcast. The caption processing unit 166 converts the caption data into a screen display format and outputs the caption content to the display unit DIS. The control unit 140 uses the contents output from the decoding unit 160 and the data broadcast processing unit 170 to configure the images and sound provided by the service being received, and based on the PTS received in advance from the TS, Control is performed so that the image and sound are synchronized and output from the display unit DIS and sound output unit 190 (speaker or earphone). The storage unit 120 stores a correspondence table (channel table) between physical frequencies and services. This channel table will be described later.

  Here, the channel selection processing (processing for presenting the service of the designated channel to the user) of the receiving apparatus 100 described above will be described based on a flowchart. FIG. 4 is a flowchart for briefly explaining the channel selection processing of the receiving apparatus 100 according to an embodiment of the present invention. First, the receiving apparatus 100 starts processing upon receiving a channel selection instruction (channel designation command) from a user or a channel selection instruction by a function unique to the receiving apparatus such as channel scanning. In step S11, the receiving unit 110 receives control of the control unit 140 based on the channel selection instruction, and starts receiving a broadcast wave that broadcasts the designated channel. The receiving unit 110 extracts the TS through frequency conversion and demodulation of the received broadcast wave. Next, in step S <b> 12, the receiving unit 110 receives the NIT multiplexed in the TS and stores it in the memory 150. In step S13, section analysis unit 130 calculates the PID of the PMT from the lower 3 bits of the service ID described in the received NIT. Thereafter, the separation unit 180 acquires (receives) the PMT having the calculated PID by filtering from the TS in step S <b> 14 and stores it in the memory 150. In step S15, the separation unit 180 extracts the TSP PID including the video, audio, and other data constituting the service of the designated channel described in the received PMT, and based on the extracted PID, Extract TSP from TS. Note that the extracted TSP is stored in the memory 150 or directly output to the decoding unit 160. In step S16, the video decoding unit 162, the audio decoding unit 164, the subtitle decoding unit 166, and the data broadcast processing unit 170 of the decoding unit 160 decode each content from the TSP output from the separation unit 180, and the control unit 140 controls the display unit DIS and the audio output unit 190 (speaker or the like) to present (output) video, audio, subtitles, and data broadcasting contents.

  Before describing the reception process of the 1-segment broadcasting service that is characteristic of the receiving apparatus 100 according to an embodiment of the present invention, the channel table will be described here. FIG. 7 shows the first channel table. As shown in the figure, there are channel tables (channel lists) for each area. In this example, there are a Kanto channel table L1, a central channel table L2, and a Kansai channel table L3. Here, the physical frequency is defined by the frequency (physical channel) itself. Further, in the case of a digital broadcast reception form such as IPTV via a network, the physical frequency is defined by a service identifier (server address or the like). For example, the broadcasting station MHK in the Kanto channel table L1 is a logical channel (channel number) 1, and this logical channel 1 has a frequency of 575 MHz of a Kanto broadcasting device (corresponding to the parent station and the broadcasting device 200), A frequency 713 MHz of a broadcasting device (corresponding to the broadcasting device 300) that broadcasts the same service as the station is associated with each other. The broadcast apparatus 300 in this example broadcasts a service (program) for each logical channel at a separate physical frequency (physical channel). Further, when the broadcasting apparatus 300 is transmitting digital broadcast via a network, the service identifier is associated with the frequency of the master station. For example, the service identifier “XXX” corresponds to the master station frequency 575 MHz of the broadcasting station MHK.

  FIG. 8 is a diagram showing the second channel table. As shown in the figure, there are channel tables (channel lists) for each area. In this example, there are a Kanto channel table L4, a central channel table L5, and a Kansai channel table L6. Here, the physical frequency is defined by a set of physical channels and segments. For example, the broadcasting station MHK in the Kanto channel table L4 is a logical channel (channel number) 1, and the logical channel 1 includes the physical channel 25 of the Kanto broadcasting apparatus (corresponding to the master station and the broadcasting apparatus 200). A set with segment number 0 is associated with a set with physical channel 50 and segment number 3 of a broadcasting apparatus (corresponding to broadcasting apparatus 300) that broadcasts the same service as Kanto. The broadcast apparatus 300 in this example broadcasts the physical channel 50 by connecting a plurality of partially receivable segments. Further, when the broadcasting apparatus 300 is transmitting a digital broadcast via a network, the service identifier and the physical channel of the master station are associated with each other as in FIG.

  As shown in FIG. 7 and FIG. 8, broadcasting can be performed by associating information (a set of physical channels and segment numbers) indicating a plurality of physical frequencies transmitted from a plurality of broadcasting stations and a service identifier with one logical channel. Even if the station or the frequency to be received changes, the same logical channel number is displayed on the screen display for the same service.

  Next, a reception process for a one-segment broadcasting service, which is characteristic of the receiving apparatus 100 according to an embodiment of the present invention, will be described. FIG. 5 is a flowchart of the reception process of the reception device 100 according to an embodiment of the present invention. First, when receiving a user instruction, the receiving apparatus 100 activates an application (such as TV viewing) that receives broadcast waves, and performs the channel selection process described with reference to FIG. 4 (step S21). Thereafter, an instruction to switch to a new channel is received from the user (step S22). In step S23, the control unit 140, based on the correspondence table (channel table) stored in the storage unit 120, the service broadcast on the switching destination channel has been received on the channel before switching until now ( It is determined whether the service is the same service (program) as the program. This determination can be made based on whether or not the service names of the channels before and after switching are the same. This will be specifically described with reference to the channel table of FIG. For example, when the channel before switching is 583 [MHz] and the channel after switching is 713 [MHz], the service broadcast on these channels is “MHK” and the service name (Service_id) is the same. The control unit 140 determines that the channel before and after switching is broadcasting the same service.

  Returning to the flowchart of FIG. If it is determined in step S23 that the switching destination channel is the same service (program) as the channel before switching, the process proceeds to step S24 and step S26. For convenience of explanation, the flow after step S23 is branched to show that the subsequent processing is performed in parallel. In step S24, receiving section 110 starts receiving the broadcast wave of the switching destination channel, and extracts the TS through frequency conversion and demodulation of the received broadcast wave. In parallel with step S24, in step S26, the receiving unit 110 decodes the data already received in the channel before switching, and displays video, audio, captions, and data broadcast. That is, the video decoding unit 162, the audio decoding unit 164, the caption decoding unit 166, and the data broadcast processing unit 170 decode each data from the received TSP, and the control unit 140 displays the display unit DIS and the audio output unit 190 ( (Speakers and the like) are controlled to present (output) video, audio, subtitles, and data broadcast content. Note that the control unit 140 waits for the display time specified by the PTS, which has been decoded when receiving the same service as that of the channel to be switched and received on the channel before the switching. If a picture (picture to be displayed) is in the buffer, this picture is also displayed.

  After step S24, buffer duplication processing described below is performed in step S25. FIG. 6 is a flowchart of the buffer duplication process of the reception process according to one embodiment of the present invention. In the receiving apparatus 100 according to an embodiment of the present invention, when the service being broadcast before and after the channel switching is the same, the receiving apparatus 100 receives the signal before the switching and terminates the decoding process as before, and is buffered. Without discarding each data (time table such as PAT, PMT, etc., and data such as decoded video / audio received based on them), the video / audio of the service is output using each data To do. Each of these data is included, for example, in a portion highlighted by hatching in the schematic diagrams of PAT, PMT, and NIT shown in FIGS. At this time, if the receiving apparatus 100 newly receives the same data as the data waiting for output buffered before switching in the switching destination channel, the receiving apparatus 100 discards the newly received data. This processing is called “buffer duplication processing” here.

  First, when another channel or a channel of another transmission method that provides the same service as the channel before switching is selected, buffer duplication processing is started. In step S31, section analysis unit 130 does not discard the data (video, audio, caption, data broadcast, program arrangement information SI, etc.) related to the service received so far, but has received the received program arrangement information SI (NIT , PMT, etc.), the data of the other channel of the switching destination that provides the same service as the channel before switching is received (step S31). That is, the receiving unit 110 receives a TSP having a PID described in a received PMT. Next, in step S32, control unit 140 determines whether or not the same data as the data received in step S31 is in the buffered data that has already been received. If it is determined that there is the same data, the process proceeds to step S33, and the control unit 140 discards the same received data and returns to step S31 to receive the next data. If it is determined in step S32 that there is no same data, the control unit 140 starts buffering the data being received in step S34, and then returns to step S27 in FIG. In step S27, control unit 140 outputs video / audio / caption / BML using the data for which buffering has been started in step S34 (FIG. 6). When the buffer duplication processing in step S25 is completed, all the data in the buffer that was output in step S26 is output in parallel with step S25, and the video / audio using the received data in step S27 is output. Seamless transition to output.

  If it is determined in step S23 that the switching destination channel is not the same service as the channel before switching, the process proceeds to step S28, and the control unit 140 discards the buffered data and the program arrangement information SI ( clear. Thereafter, the channel selection process described in the flowchart of FIG. 4 is performed (step S29), and the reception process by the reception apparatus 100 according to an embodiment of the present invention is completed.

  Here, the reception process according to the embodiment of the present invention is compared with the reception process according to the prior art using the drawings. First, the reception processing of the receiving apparatus according to the prior art will be described based on the flowchart shown in FIG. When a receiving apparatus according to the conventional technique starts an application that receives a digital broadcast, in step S41, the above-described channel selection process of FIG. 4 is performed. Thereafter, when the channel is switched by a switching instruction from the user or by a function unique to the receiving device such as channel scanning (step S42), the switching is performed in step S43 in the prior art, unlike the receiving device 100 according to the present invention. Data (video, audio, etc.) and program information SI received in the previous channel are discarded (cleared). Thereafter, in step S44, the channel selection process of FIG. 4 is performed in the channel to be switched to. As described above, in the prior art, regardless of the content of the service broadcast on the channel before and after the switching, all data received on the channel before the switching is discarded, and the channel selection process for the channel to be switched to is performed.

  Next, the advantage that the reception process according to the present invention can execute the reception process at the time of channel switching faster than the prior art will be described with reference to the drawings. FIG. 9 is a diagram schematically illustrating a time required until certain data is output. As shown in the upper part of the figure, until the data is output, the waiting time until the NIT is received, the waiting time until the PMT is received, the waiting time until the IDR picture is received, and the received data are It takes a waiting time until the display time specified by PCR is reached. It is assumed that the channel is switched at time 0 [ms] in the figure, and the channel to be switched to provides the same service as the channel before switching. Even in this case, as shown in the lower part of the figure, in the prior art, the NIT, PMT, etc. received so far are discarded, and NIT, PMT, etc. are newly received on the switching destination channel. With reference to Non-Patent Documents 1 and 2, the waiting time is 1 second for the NIT retransmission period of the partial reception layer, 200 ms for the PMT retransmission period, and normally 2 seconds for the I picture transmission period of the video of the partial reception layer. Therefore, it usually takes a maximum of 3.2 seconds to receive the IDR. Furthermore, even if the IDR is received, it is necessary to wait until the display time calculated from the PCR and the PTS. In the figure, the display wait time is set to 1.2 seconds. Therefore, in the prior art, it takes 4.4 seconds from the time when the channel is switched until the video or audio is output. On the other hand, in the method according to the present invention shown in the middle of the figure, even if the channel is switched, the data received in the channel before switching and the decoded data are used. As shown in the figure, when there is a decoded picture received on the channel before switching and output for 0.4 seconds, video and audio can be output after 0.4 seconds. Therefore, it is possible to output a video or the like up to 4 seconds earlier than the conventional method. Even if there are no pictures waiting to be displayed, if there is received data, it will be displayed by appropriate decoding processing, so it is clear that the data display time is faster compared to the conventional method in which all received data is discarded It is.

  The effect of the present invention will be described again. According to the present invention, when switching to a channel broadcasting the same service as the channel being received, the content of the service of the switching destination channel is received using the PMT that has already been received before the switching. Therefore, the PMT received before the switching is discarded, and it is possible to wait for the reception of the PMT of the switching destination channel before receiving the service content of the switching destination channel. Channel selection processing (that is, provision of service contents to users) can be accelerated. Further, according to the present invention, the same service as that of the switching destination channel is broadcast, and the PMT of the service of the channel received until immediately before switching is used. Therefore, the possibility that the PMT is not updated is low and the reliability is high. Further, according to the present invention, if the same service is used, the data received by the channel service before the switching is not discarded, and the service is also used for the channel of the switching destination. Less is. For this reason, the time to start displaying the content of the switching destination service can be made faster than the conventional method. In addition, if the data received on the channel before switching and the data (data such as audio / video) received on the switching destination channel overlap, either one is discarded. Therefore, video and audio are not repeatedly output.

  Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and corrections based on the present disclosure. Therefore, it should be noted that these variations and modifications are included in the scope of the present invention. For example, the functions included in each part, each step, etc. can be rearranged so as not to be logically contradictory, and a plurality of constituent parts, steps, etc. can be combined into one or divided. .

  For example, the present invention can be applied to all services provided in the MPEG2-TS format. That is, although the present invention has been described for one segment broadcasting, it is obvious that the present invention can be applied to 12 segment broadcasting. In that case, NIT was used for receiving the PMT in the tuning process of 1 segment broadcast. However, in the case of 12 segment broadcast, the PMT may be received based on the contents described in the PAT. In the embodiment, when the channel is switched, it is determined whether or not the service of the channel before and after the switching is the same, but it should be noted that the present invention is not limited to this. For example, when a user moves to an out-of-service area of a broadcast wave of a channel, the receiving apparatus according to the present invention automatically changes to a broadcast wave broadcasting the same service as the channel before switching based on the channel table. It can also be switched. In this case, the receiving apparatus according to the present invention can perform seamless channel switching with good usability without interruption of video or the like.

  Further, it is conceivable that a digital broadcast receiving apparatus receives a broadcast via a network such as IPTV. In this case, when the reception of the digital broadcast is switched from the broadcast wave to that via the network, the channel table shown in FIGS. 7 and 8 is used to determine the service before and after the switch based on the correspondence between the service and the service identifier. Identity can be determined.

Claims (5)

A digital broadcast receiver for a digital broadcast system that broadcasts the same service at a plurality of physical frequencies,
A storage unit that stores information indicating a plurality of physical frequencies that broadcast the same service;
An acquisition unit for acquiring a PMT from a digital broadcast;
A receiving unit that receives data of a desired service from digital broadcasting based on the PMT acquired by the acquiring unit;
During reception of a digital broadcast service, based on the information stored in the storage unit, the service is switched to another physical frequency different from the physical frequency at which the service being received is broadcast, and is the same as the service being received When receiving the service, the PMT of the receiving service acquired by the acquiring unit is used to receive data of the same service as the receiving service broadcast on the different physical frequency. A control unit for controlling the receiving unit;
A digital broadcast receiver characterized by comprising: The digital broadcast receiver according to claim 1,
When switching to a different frequency from the physical frequency for broadcasting the service being received and receiving the same service as the service being received,
The control unit does not discard the data of the service being received acquired by the acquisition unit, and uses it as data of the same service as the service being received that is being broadcast on the different physical frequency.
A digital broadcast receiver characterized by that. The digital broadcast receiver according to claim 1,
Each of the physical frequencies is a physical channel.
A digital broadcast receiver characterized by that. The digital broadcast receiver according to claim 1,
Each of the physical frequencies is information indicating a physical channel and an OFDM segment.
A digital broadcast receiver characterized by that. A digital broadcast receiving device of a digital broadcast system that provides the same service with a plurality of service identifiers via a network,
A storage unit for storing information indicating a plurality of service identifiers providing the same service;
An acquisition unit for acquiring a PMT from a digital broadcast;
A receiving unit that receives data of a desired service from digital broadcasting based on the PMT acquired by the acquiring unit;
During reception of a digital broadcast service, based on the information stored in the storage unit, the service identifier is switched to another service identifier different from the service identifier that provides the service being received, and is the same as the service being received When receiving the service, the PMT of the service being received acquired by the acquisition unit is used to receive data of the same service as the service being received provided by the other service identifier. A control unit for controlling the receiving unit;
A digital broadcast receiver characterized by comprising:

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