JP2010034994A - Digital broadcasting receiver and receiving method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a digital broadcasting receiver that can swiftly and smoothly switch to a second digital broadcasting from a first digital broadcasting. <P>SOLUTION: The digital broadcasting receiver 100 is provided with: a 12-segment video decoding section 105 for decoding video image stream data separated from the stream data of 12-segment broadcasting; a one-segment video decoding section 112 for decoding video image stream data separated from the stream data of one-segment broadcasting; and a stream buffer 111 for holding the video image stream data of the one-segment broadcasting while the 12-segment broadcasting is selected. The 12-segment video decoding section 105 performs fast decoding of the video image stream data for one-segment broadcasting in the stream buffer 111 when the output display selection is switched to one-segment broadcasting from 12-segment broadcasting. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a digital broadcast receiving apparatus having a function of receiving a plurality of stream data of the same program transmitted simultaneously in two digital broadcasts, and more particularly to switching between two digital broadcast streams to decode and display a video. It is related to the technology.

  In Japanese terrestrial digital broadcasting, the transmission band can be divided into 13 segments, and the modulation method can be changed in units of segments. That is, a plurality of types of modulation schemes can be combined and transmitted. For example, among the 13 segments, it is possible to transmit a high-definition broadcast for a fixed receiver using 12 segments and transmit a simple broadcast for a portable receiver using one segment. A hierarchy using 12 segments is called a weak hierarchy because the transmission radio wave intensity of digital broadcasting is weak, and a hierarchy using 1 segment is called a strong hierarchy because the transmission radio wave intensity of digital broadcasting is strong. Since the layer using one segment is modulated by a modulation method having a higher noise resistance than the layer using 12 segments, reception in an environment where the reception environment is worse than that of a layer using 12 segments is possible. It becomes a hierarchy with strong transmission strength. In addition to the division into 12 segments and 1 segment, a transmission system for digital broadcasting divided into 3 segments and 9 segments is also conceivable. Further, in a hierarchy using 12 segments, a high definition broadcast (HD broadcast) program is transmitted using 12 segments, and a standard definition broadcast (SD broadcast) is used using 4 of 12 segments. A program may be transmitted.

  12-segment broadcasting (simply referred to as 12-segment broadcasting) can provide high-definition video and audio using a wide transmission band, but is vulnerable to noise and unsuitable for reception while moving. On the other hand, 1-segment broadcasting (simply referred to as 1-segment broadcasting) has a narrow transmission band and simple video and audio broadcasting, but is also suitable for reception while moving more strongly than noise than 12-segment broadcasting. In recent years, simulcast broadcasting that provides the same program by 12-segment broadcasting and 1-segment broadcasting having the above-described characteristics has been implemented.

Conventional digital broadcast receivers are compatible with both weak-segment 12-segment broadcasts and strong-segment 1-segment broadcasts. There is known a vehicle-mounted digital broadcast receiving apparatus that outputs video and audio by switching between 1-segment broadcasting (see, for example, Patent Document 1). In this conventional digital broadcast receiver, referring to either the electric field strength from the tuner, the bit error rate from the demodulator, or the number of macro blocks of block noise from the decoder, the 12-segment broadcast and the 1-segment broadcast to be output are output. The output was selected and switched.
Japanese Patent Laying-Open No. 2005-277873 (FIG. 1)

  In the conventional digital broadcast receiving apparatus, if the reception state of the 12-segment broadcast is good, the 12-segment broadcast providing the high-definition broadcast is output, and the reception state of the 12-segment broadcast deteriorates due to movement, so that sufficient video and audio When the output becomes difficult, it is switched to the broadcast of the same program of one segment broadcast that can be received even if the reception state is bad. However, in the conventional digital broadcast receiving apparatus, there is no mention regarding detailed switching processing from 12-segment broadcast to 1-segment broadcast.

  In such a conventional digital broadcast receiving apparatus, for example, after determining to switch from 12-segment broadcast to 1-segment broadcast, stream data of 1-segment broadcast is received, and video stream data is extracted from the received stream data. Until the video is decoded, the display video cannot be output, and the last distorted video of the 12-segment broadcast whose reception status has deteriorated is output or the blackout output screen is displayed for a long time. There is a problem of giving pleasure.

  Since video stream data obtained by compressing and encoding video data compresses difference data between frames, an intra-frame prediction frame (also referred to as an intra frame or I frame) from which difference data between frames is taken is not decoded. As long as the following inter-frame prediction frame (also referred to as P frame) cannot be decoded, decoding cannot be performed until video stream data including intra frame data is received. There is a problem that there is an interval of about 2 seconds as a display time of the next intra frame, and an interval of 5 seconds may be opened at the maximum.

  Therefore, a method of switching the output by decoding the video stream data of both the 12-segment broadcast and the 1-segment broadcast is also conceivable. However, in this case, it is necessary to always decode the video stream data of both broadcasts. There is a problem that electric power increases.

  The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide a digital broadcast receiving apparatus capable of quickly and smoothly switching from the first digital broadcast to the second digital broadcast. And

  The digital broadcast receiving apparatus of the present invention is a digital broadcast receiving apparatus having a function of receiving a plurality of stream data of a first digital broadcast and a second digital broadcast that transmit the same program at the same time. The broadcast has a transmission band set larger than that of the second digital broadcast, and the second digital broadcast has a transmission radio wave intensity set stronger than that of the first digital broadcast. The apparatus decodes the video stream data separated from the stream data of the second digital broadcast, and the first video decoding means for decoding the video stream data separated from the stream data of the first digital broadcast. The second video decoding means and the first digital broadcast according to the reception quality of the first digital broadcast, Control means for performing switching control of digital broadcasting for selecting either digital broadcasting or the second digital broadcasting as a display output; and when the first digital broadcasting is selected, the second digital broadcasting Stream holding means for holding the video stream data, wherein the first video decoding means is configured to switch the display output selection from the first digital broadcast to the second digital broadcast. The video stream data of the second digital broadcast held in the stream holding means is decoded at a higher speed than the second video decoding means.

  The digital broadcast receiving method of the present invention is a digital broadcast receiving method used in a digital broadcast receiving apparatus having a function of receiving a plurality of stream data of a first digital broadcast and a second digital broadcast that simultaneously transmit the same program. Thus, the first digital broadcast has a transmission band set larger than that of the second digital broadcast, and the second digital broadcast has a transmission radio wave intensity set stronger than that of the first digital broadcast. And the digital broadcast receiving apparatus separates the first video decoding means for decoding the video stream data separated from the first digital broadcast stream data and the second digital broadcast stream data. Second video decoding means for decoding the received video stream data, The digital broadcasting receiving method performs switching control of digital broadcasting for selecting one of the first digital broadcasting and the second digital broadcasting as a display output according to the reception quality of the first digital broadcasting, When the first digital broadcast is selected, the video stream data of the second digital broadcast is held, and the display output selection is switched from the first digital broadcast to the second digital broadcast. In some cases, the first video decoding means is used to decode the video stream data of the second digital broadcast held in the stream holding means at a higher speed than the second video decoding means.

  According to the present invention, when the selection is switched from the first digital broadcast to the second digital broadcast, the video stream data of the second digital broadcast retained when the first digital broadcast is selected. A digital broadcast receiving apparatus having an effect of being able to quickly and smoothly switch from the first digital broadcast to the second digital broadcast by performing high-speed decoding processing using the first video decoding means. It can be provided.

  Hereinafter, a digital broadcast receiver according to an embodiment of the present invention will be described with reference to the drawings. In the present embodiment, a case of a digital broadcast receiving apparatus that receives the same program that is simultaneously broadcast by two digital broadcasts (12-segment broadcast and 1-segment broadcast) is illustrated. This digital broadcast receiving apparatus is applied to, for example, mobile terminals such as mobile phones, mobile TVs, and portable navigation devices, and in-vehicle navigation devices.

(First embodiment)
A digital broadcast receiver according to a first embodiment of the present invention will be described with reference to FIGS. Here, first, the configuration of the digital broadcast receiving apparatus according to the present embodiment will be described.

  FIG. 1 is a block diagram showing a configuration of a digital broadcast receiving apparatus according to the present embodiment. As shown in FIG. 1, the digital broadcast receiving apparatus 100 has a 12-segment tuner 101, a 12-segment demodulation unit 102, a 12-segment demultiplexing unit 103, and 12 as a configuration for processing reception data of 12-segment broadcasting. A segment buffer 104, a 12-segment video decoding unit 105, and a 12-segment frame buffer 106 are provided.

  The 12-segment tuner 101 receives modulation data of a designated program of 12 segment broadcast, which is weak digital broadcast, from a digital broadcast wave received by an antenna. In addition, the electric field strength indicating the reception strength of the modulation data is measured, and the measured electric field strength value is transmitted to the control unit 115.

  The 12-segment demodulation unit 102 demodulates the modulated data from the 12-segment tuner 101 and outputs the demodulated transport stream (TS) data to the 12-segment demultiplexing unit 103. Further, the bit error rate of the transport stream data at the time of demodulation is measured, and the measured bit error rate is transmitted to the control unit 115.

  The 12-segment demultiplexing unit 103 receives the transport stream data from the 12-segment demodulating unit 102. If the input transport stream data is scrambled, the 12-segment demultiplexing unit 103 releases the descrambling (descrambling process) and performs multiplexing. The converted transport stream is separated into video stream data, audio stream data, and section data including program information, and each separated data is output to the stream buffer 104.

  The stream buffer 104 holds data input from the 12-segment demultiplexing unit 103. The input video stream data is decoded by the 12-segment video decoding unit 105, and the audio stream data is audio-decoded by an audio decoding unit (not shown) and output to an external speaker or the like. The section data is separately processed by a processor unit such as a CPU (not shown).

  The 12-segment video decoding unit 105 receives the video stream data held in the stream buffer 104 as input, performs decoding processing, and outputs the video data to the frame buffer 106.

  The frame buffer 106 holds the video data decoded by the 12-segment video decoding unit 105.

  As shown in FIG. 1, the digital broadcast receiving apparatus 100 has a 1-segment tuner 107, a 1-segment demodulation unit 108, a 1-segment demultiplexing unit 109, and a configuration for processing reception data of 1-segment broadcasting. , An I-frame detection unit 110, a 1-segment stream buffer 111, a 1-segment video decoding unit 112, and a 1-segment frame buffer 113.

  The 1-segment tuner 107 receives modulation data of a designated program of 1-segment broadcast, which is a strong digital broadcast, from a digital broadcast wave received by an antenna. In addition, the electric field strength indicating the reception strength of the modulation data is measured, and the measured electric field strength value is transmitted to the control unit 115.

  The 1-segment demodulator 108 demodulates the modulated data from the 1-segment tuner 107 and outputs the demodulated transport stream (TS) data to the 1-segment demultiplexer 109. Further, the bit error rate of the transport stream data at the time of demodulation is measured, and the measured bit error rate is transmitted to the control unit 115.

  The 1-segment demultiplexing unit 109 receives the transport stream data from the 1-segment demodulation unit 108 and separates the multiplexed transport stream into video stream data, audio stream data, and section data including program information. The separated data are output to the stream buffer 111.

  The I-frame detection unit 110 detects a synchronization word representing the head of the frame from the video stream data separated by the 1-segment demultiplexing unit 109, analyzes the subsequent frame header information to identify the picture type of the frame, and The head data of the video stream data is detected.

  The stream buffer 111 holds data input from the 1-segment demultiplexing unit 109. The input video stream data is decoded by the 1-segment video decoding unit 112, and the audio stream data is audio-decoded by an audio decoding unit (not shown) and output to an external speaker or the like. The section data is separately processed by a processor unit such as a CPU (not shown).

  Here, it can be said that the 1-segment demultiplexing unit 109, the I frame detection unit 110, and the stream buffer 111 form a 1-segment demultiplexing block (shown by a dotted line in FIG. 1).

  The 1-segment video decoding unit 112 receives the video stream data held in the stream buffer 111 as input, performs decoding processing, and outputs the video data to the frame buffer 113.

  The frame buffer 113 holds the video data decoded by the 1 segment video decoding unit 112.

  As shown in FIG. 1, the digital broadcast receiving apparatus 100 includes a display output unit 114, a control unit 115, and a liquid crystal display (LCD) 116.

  The display output unit 114 receives the 12-segment broadcast video data held in the frame buffer 106 and the 1-segment broadcast video data held in the frame buffer 113 as input, and receives the broadcast-side video data instructed from the control unit 115. Image processing such as enlargement / reduction processing, rotation processing, and high image quality processing necessary for selection and output to the external display device is executed and output to the LCD 116.

  The control unit 115 receives the electric field strength from the 12-segment tuner 101, the bit error rate from the 12-segment demodulation unit 102, the electric field strength from the 1-segment tuner 107, and the bit error rate from the 1-segment demodulation unit 108 as inputs. The quality of the 12-segment broadcast and 1-segment broadcast received from the strength and bit error rate is judged. If the reception quality of the 12-segment broadcast is equal to or higher than the predetermined quality, the 12-segment broadcast output is selected. If the reception quality is lower than the predetermined quality and the reception quality of the one-segment broadcast is equal to or higher than the predetermined quality, the output of the one-segment broadcast is selected. If the reception quality of the one-segment broadcast is lower than the predetermined quality, whichever Choose not to output any broadcasts. According to the selected result, the video data to be output to the display output unit 114 is instructed, the 12-segment tuner 101, the 12-segment demodulation unit 102, the 12-segment demultiplexing unit 103, the 12-segment video decoding unit 105, the 1-segment tuner 107, Necessary control instructions are output to the 1-segment demodulating unit 108, the 1-segment demultiplexing unit 109, and the 1-segment video decoding unit 112.

  In addition, when it is detected from the section data processing, EPG information, etc. that a 1-segment broadcast program that is the same program as the 12-segment broadcast is not broadcast, the output of the 1-segment broadcast is not selected.

  The digital broadcast receiving apparatus 100 includes power supply clock control units 117 to 122.

  The power supply clock control units 117 to 122 are blocks that control the power supply voltage and the clock, and stop the clock or shut off the power supply. The power supply clock control unit 117 controls the power supply and clock of the 12-segment tuner 101 and the 12-segment demodulation unit 102, the power supply clock control unit 118 controls the power supply and clock of the 12-segment demultiplexing unit 103, and the power supply clock control unit 119 The power and clock of the 12-segment video decoding unit 105 are controlled. The power clock control unit 120 controls the power and clock of the 1 segment tuner 107 and the 1 segment demodulator 108, the power clock control unit 121 controls the power and clock of the 1 segment demultiplexing unit 109, and the power clock control unit 122 The power supply and clock of the 1-segment video decoding unit 112 are controlled.

  The stream buffer 104, the frame buffer 106, the stream buffer 111, and the frame buffer 113 may be secured in a memory area on the same SDRAM.

  Here, the video stream data will be described. FIG. 2 is an explanatory diagram of a frame sequence constituting video stream data of 1 segment broadcasting. As shown in FIG. 2, the plurality of frames constituting the video stream data are arranged in the order of display in the time axis direction on the horizontal axis. In FIG. 2, a rectangle written as I or P represents one frame. The frame described as I represents an intra frame, and the frame described as P represents an inter-screen prediction frame. As described above, the video stream data is configured in the data order of frames in the same sequence as the display order.

  The operation of the digital broadcast receiving apparatus 100 according to the first embodiment configured as described above will be described with reference to the drawings.

  FIG. 3 is a diagram illustrating a processing flow of a digital broadcast receiving operation using the digital broadcast receiving apparatus 100 according to the first embodiment. As shown in FIG. 3, at the start of digital broadcast reception, the 12-segment tuner 101 and the 12-segment demodulator 102, the 1-segment tuner 107 and the 1-segment demodulator 108 are operated, and the broadcast station program designated by the user is operated. Receive 12-segment broadcast and 1-segment broadcast programs. Then, the electric field strength and the bit error rate of each broadcast wave are acquired, and the control unit 115 determines whether to output a 12-segment broadcast or a 1-segment broadcast (S100).

  As a result of the determination by the control unit 115 (S100), if the reception quality of the 12-segment broadcast is equal to or higher than a predetermined quality, the 12-segment broadcast that can output high-definition video and audio is selected and output (S101). The 12 segment broadcast reception output process will be described later with reference to the drawings.

  While the 12-segment broadcast is being output, the reception quality of the 12-segment broadcast is below a predetermined quality (S102), and the reception quality of the 1-segment broadcast is equal to or higher than the predetermined quality (S103) A switching process is performed (S104). The switching process from the 12-segment broadcasting to the 1-segment broadcasting will also be described later with reference to the drawings.

  As a result of the determination by the control unit 115 (S100), when the reception quality of the 12-segment broadcast is lower than the predetermined quality and the reception quality of the 1-segment broadcast is equal to or higher than the predetermined quality, the 1-segment broadcast is selected and output ( S105). The one-segment broadcast reception output process will be described later with reference to the drawings.

  If the reception quality of the one-segment broadcast falls below a predetermined quality during the output of the one-segment broadcast (S106), a reception output disable notification process is performed. This reception output disable notification process will also be described later with reference to the drawings.

  If the reception quality of the 12-segment broadcast is equal to or higher than the predetermined quality during the output of the 1-segment broadcast (S107), a switching process is performed so as to output the 12-segment broadcast (S108). This switching process from 1-segment broadcasting to 12-segment broadcasting will also be described later with reference to the drawings.

  As a result of the determination by the control unit 115 (S100), if the reception quality of both the 12-segment broadcast and the 1-segment broadcast is lower than the predetermined quality, a reception output disable notification process is performed (S109).

(12 segment broadcast reception output processing)
Here, the 12-segment broadcast reception output process will be described with reference to FIG. FIG. 4 is a diagram showing a processing flow of 12 segment broadcast reception output processing. In the 12-segment broadcast reception and output process, a 12-segment tuner 101, a 12-segment demodulation unit 102, a 12-segment demultiplexing unit 103, a stream buffer 104, a 12-segment video decoding unit 105, a frame, which are used when receiving and outputting a 12-segment broadcast The buffer 106 and the display output unit 114 are operated.

  Specifically, as shown in FIG. 4, the 12-segment tuner 101, the 12-segment demodulation unit 102, the 12-segment demultiplexing unit 103, and the 12-segment video decoding unit 105 are activated to perform reception and decoding (S111), The decoded frame of the 12-segment video decoding unit 105 is output from the display output unit 114 to the LCD 116 (S112).

  1 segment tuner 107, 1 segment demodulator 108, 1 segment demultiplexer 109, I frame detector 110, and stream buffer 111 are receiving and outputting 12 segment broadcasts in preparation for switching from 12 segment broadcasts to 1 segment broadcasts. Also make it work. Then, the 1-segment tuner 107, the 1-segment demodulation unit 108, and the 1-segment demultiplexing unit 109 receive the stream data of the same program as the 12-segment broadcast program and store it in the stream buffer 111 (S113).

  However, for the video stream data separated by the 1-segment demultiplexing unit 109, the I frame detection unit 110 detects the leading data of the intra frame, and the stream data from the detected leading data of the intra frame is the stream buffer 111. Operates to save to. In the process of storing the video stream data, at the stage of detecting and storing the leading data of the next intra frame, the stream data from the leading data of the previous intra frame to the leading data of the detected intra frame may be discarded. In this way, the memory capacity reserved in the stream buffer 111 can be reduced by storing from the head data of the intra frame.

  In this case, since the 1-segment broadcast is not output, the power supply clock control unit 122 outputs an instruction from the control unit 115 to turn off the power of the 1-segment video decoding unit 112 or stop the clock. In this way, the 1-segment video decoding unit 112 is shifted to the low power mode (S114).

(1 segment broadcast reception output processing)
Next, the one-segment broadcast reception output process will be described with reference to FIG. FIG. 5 is a diagram showing a process flow of the one-segment broadcast reception output process. In the 1-segment broadcast reception output process, a 1-segment tuner 107, a 1-segment demodulation unit 108, a 1-segment demultiplexing unit 109, a stream buffer 111, a 1-segment video decoding unit 112, a frame used for receiving and outputting a 1-segment broadcast The buffer 113 and the display output unit 114 are operated.

  Specifically, as shown in FIG. 5, the 1-segment tuner 107, the 1-segment demodulation unit 108, the 1-segment demultiplexing unit 109, the 1-segment video decoding unit 112 are activated to perform reception and decoding (S121), The decoded frame of the 1-segment video decoding unit 112 is output from the display output unit 114 to the LCD 116 (S122).

  At this time, if the 12-segment tuner 101 is stopped, the 12-segment tuner 101 is activated (S123), receives the broadcast wave of the 12-segment broadcast, measures the electric field strength, and recovers the reception quality of the 12-segment broadcast to a predetermined quality or higher. To detect.

  In this case, since the 12-segment broadcast is not output, the control unit 115 causes the power supply clock control unit 118 and the power supply clock control unit 119 to turn off the power of the 12-segment demultiplexing unit 103 and the 12-segment video decoding unit 105 or stop the clock. Will output instructions. In this way, the 12-segment video decoding unit 105 is shifted to the low power mode (S124). The power supply clock control unit 117 may shut off the power of the 12-segment demodulation unit 102 or stop the clock.

(Reception output disabled notification processing)
Next, the reception output disable notification process will be described with reference to FIG. FIG. 6 is a diagram illustrating a process flow of the reception output disable notification process. As shown in FIG. 6, in this reception output impossibility notification process, the display output unit 114 displays that the digital broadcast cannot be received from the display 116 (S131).

(Switching from 12-segment broadcasting to 1-segment broadcasting)
Switching processing from 12-segment broadcasting to 1-segment broadcasting is a characteristic operation of the present invention. For example, as a result of using the digital broadcast receiving apparatus 100 while moving, at the time of receiving and outputting 12-segment broadcasting, This is an operation in the case where the reception quality of the segment broadcast is lower than the predetermined quality and the reception output operation cannot be sufficiently performed and the operation is switched to the reception and output of the one-segment broadcast.

  Specifically, when the control unit 115 detects that the reception quality of the 12-segment broadcast is lower than a predetermined quality based on the electric field strength and the bit error rate from the 12-segment tuner 101 and the 12-segment demodulation unit 102, first, the 1-segment tuner The reception quality of the one-segment broadcast is confirmed from the electric field intensity from 107. When the reception quality of the 1-segment broadcast is equal to or higher than the predetermined quality and the same program as the 12-segment broadcast program being received and output is received, switching to reception and output of the 1-segment broadcast is performed. When the reception quality of the one-segment broadcast is lower than the predetermined quality, since there is no broadcast that can be received and output, the display output unit 114 displays on the screen that the digital broadcast cannot be received and notifies the user.

  Here, switching processing from 12-segment broadcasting to 1-segment broadcasting will be described in more detail with reference to the drawings. FIG. 7 is a diagram illustrating a processing flow of switching processing from 12-segment broadcasting to 1-segment broadcasting. As shown in FIG. 7, when switching processing from 12-segment broadcasting to 1-segment broadcasting is started, high-speed decoding processing of video stream data of 1-segment broadcasting stored in the stream buffer 111 is performed by a 12-segment video decoding unit. The process is executed at 105 (S141). The 12-segment broadcast video has higher definition than the 1-segment broadcast video (for example, resolution 1920 × 1080, resolution of 320 × 240, 15 frames / second for 60 fields / second). Has higher decoding performance than the 1-segment video decoding unit 112, and the speed for high-speed decoding is higher when the 12-segment video decoding unit 105 is used.

  When the high-speed decoding process by the video decoding unit 105 is executed and a displayable frame after switching is detected (S142), the 12 segments stored in the frame buffer 106 are displayed on the LCD 116 from the display output unit 114. The broadcast frame data is switched to the switched one-segment broadcast display frame data stored in the frame buffer 113 (S143).

  In this case, every time a frame is decoded, frame data that can be displayed after switching is detected from display time information (for example, PTS (Present Time Stamp) information) of the decoded frame, and a display frame after switching is determined. The frame that can be displayed here means a frame that can be synchronized when the display time information is switched and displayed at a time earlier than the current time, not at a time earlier than the current time. The 1-segment video decoding unit 112 can perform decoding processing at a higher speed than the decoding processing at the normal playback frame rate. Usually, the video decoding unit can perform high-speed decoding processing by supporting the fast-forward function or the like.

  When the display frame after switching is determined in parallel with the display switching to the one-segment broadcast frame, the decoding speed of the 12-segment video decoding unit 105 is changed to the normal playback frame rate (S144), and the I-frame detection unit 110 is changed. When the next intra frame is detected, the 12-segment video decoding unit 105 executes the decoding process up to the immediately preceding inter-frame prediction frame (P frame), and the 1-segment video decoding unit 112 normally performs decoding from the subsequent intra-frame decoding process. The decoding process is changed to the playback frame rate, and the one-segment broadcast reception output process is continued (S145). Then, the process of the I frame detection unit 110, which is an unnecessary process in the one-segment broadcast reception output process, is stopped. (S146).

  In the case of the processing flow of FIG. 7, the 12-segment video decoding unit 105 needs to support decoding of 1-segment broadcast video stream data in addition to 12-segment broadcast video stream data. This is because the standard is different between the 12-segment broadcast video stream data moving picture compression / decompression standard (MPEG-2) and the 1-segment broadcast video stream data video compression / decompression standard (H.264). As one of the realization configurations of such a 12-segment video decoding unit 105, a dedicated circuit or DSP that can programmably support processing of parts different in each standard and a dedicated processing part for processing a common processing part A circuit composed of a circuit is conceivable.

  Note that a method different from FIG. 7 may be used as the switching process from the 12-segment broadcast to the 1-segment broadcast. For example, frame decoding from an intra frame of 1-segment broadcast video stream data stored in the stream buffer 111 in advance is performed by a 1-segment video decoding unit 112 at a normal frame rate (15 frames for 1-segment broadcast) with maximum processing performance. / Second).

(Switching from 1-segment broadcasting to 12-segment broadcasting)
The switching process from 1-segment broadcasting to 12-segment broadcasting is performed when the 1-segment broadcast is received and output, such as when the digital broadcast receiving apparatus 100 of the present invention is used while moving, the reception quality of the 12-segment broadcast exceeds a predetermined quality. This is the operation when switching to reception and output of 1-segment broadcasting.

  Specifically, when the control unit 115 detects that the reception quality of the 12-segment broadcast is stable and exceeds a predetermined quality due to the electric field strength from the 12-segment tuner 101, the control is switched to reception and output of the 12-segment broadcast.

  Here, the switching process from 1-segment broadcasting to 12-segment broadcasting will be described in more detail with reference to the drawings. FIG. 8 is a diagram showing a processing flow of switching processing from 1-segment broadcasting to 12-segment broadcasting. As shown in FIG. 8, when the switching process from the 1-segment broadcasting to the 12-segment broadcasting is started, the low-power mode of the 12-segment demodulation unit 102, the 12-segment demultiplexing unit 103, and the 12-segment video decoding unit 105 is canceled. And starts the demodulation process, demultiplexing process and video decoding process of the 12-segment broadcast wave (S151).

  Then, it waits until the frame data after display switching output from the 12-segment video decoding unit 105 to the frame buffer 106 is output (S152). When the frame data after display switching is output, the display output unit 114 The display output on the LCD 116 is switched from the frame data from the 1-segment video decoding unit 112 to the frame data after the display switching of the 12-segment broadcast stored in the frame buffer 106 (S153).

  In this switching process, since the reception output of 1-segment broadcasting is operating stably, there is no need to rush to switching to 12-segment broadcasting. Accordingly, the decoding process by the 12-segment video decoding unit 105 does not need to catch up with the display frame by high-speed decoding, and may be started from the intra-frame decoding process.

  Note that the processing of the control unit 115 may be realized by processor processing in the CPU, but the scope of the present invention is not limited to this, and may be realized separately by sequence processing in a dedicated circuit. Good.

  According to the digital broadcast receiving apparatus 100 of the first embodiment of the present invention, when the selection is switched from the 12-segment broadcast to the 1-segment broadcast, it is retained when the 12-segment broadcast is selected. By switching the video stream data of the 1-segment broadcast at high speed using the 12-segment video decoding unit 105, switching from the 12-segment broadcast to the 1-segment broadcast can be performed quickly and smoothly.

  That is, in the digital broadcast receiving apparatus 100 of the present embodiment, the broadcast output is switched between the 12-segment broadcast and the 1-segment broadcast according to the reception status of the 12-segment broadcast. The output can be prevented from being delayed, and at the same time, low power consumption can be realized.

  Specifically, in digital broadcast receiving apparatus 100 of the present embodiment, it is possible to switch the display output of 12-segment broadcast and 1-segment broadcast according to the reception status of 12-segment broadcast. At the time of switching to the segment broadcasting, the 12-segment video decoding unit 105 prepares the necessary frame data after the switching using the video stream data including the intra-frame of one segment broadcasting stored in the stream buffer in advance. Can do. Therefore, video output after switching to 1-segment broadcasting can be executed immediately. Furthermore, since both the 12-segment video decoding unit 105 and the 1-segment video decoding unit 112 are not always executed, and both are selectively used in the low power mode, execution with low power consumption is possible.

  According to such a digital broadcast receiving apparatus 100, the display output of 12-segment broadcasting and 1-segment broadcasting can be switched according to the reception state of 12-segment broadcasting, and switching from 12-segment broadcasting to 1-segment broadcasting is possible. In some cases, the video output after switching can be immediately output with low power consumption so as not to cause discomfort to the user.

  In this digital broadcast receiving apparatus 100, since the video decoders 105 and 112 that are not used are set in the low power mode, it is possible to save the power of the apparatus.

  Also, in this digital broadcast receiving apparatus 100, when the selection is switched from 12-segment broadcasting to 1-segment broadcasting, video stream data of 1-segment broadcasting is used using the intra-frame data held in the stream buffer 111. The decoding process can be started immediately. Therefore, switching from 12-segment broadcasting to 1-segment broadcasting can be performed quickly and smoothly.

  According to the digital broadcast receiving apparatus 100 as described above, when the reception output is switched between the 12-segment broadcast and the 1-segment broadcast according to the reception status, in particular, the reception status of the 12-segment broadcast deteriorates and the 1-segment broadcast is changed. Even when the reception output is switched, the 12-segment video decoding unit 105 uses the video stream data including the intra-frame of the one-segment broadcasting stored in the buffer 111 in advance to perform necessary frame data decoding at high speed and prepare it. The video output after switching can be executed immediately. In addition, since both the video decoding unit 105 for 12-segment broadcasting and the video decoding unit 112 for 1-segment broadcasting are not used at all times and are used in a low power mode, execution with low power consumption is possible. Furthermore, the video decoding unit 105 for 12-segment broadcasting, which has higher performance than the video decoding unit 112 for 1-segment broadcasting, is also compatible with the decoding processing of the video stream for 1-segment broadcasting, and the video stream for 1-segment broadcasting is converted to 1 segment. By performing decoding processing at a higher speed than the broadcast video decoding unit 112, it is possible to further reduce the time required for display switching.

(Second Embodiment)
Next, a digital broadcast receiver according to a second embodiment of the present invention will be described with reference to FIGS. Here, the configuration of the digital broadcast receiving apparatus according to the present embodiment will be described focusing on differences from the first embodiment. That is, unless otherwise specified here, the configuration of the digital broadcast receiving apparatus of the present embodiment is the same as that of the first embodiment.

  FIG. 9 is a block diagram showing a configuration of the digital broadcast receiving apparatus according to the present embodiment. As shown in FIG. 9, the digital broadcast receiving apparatus 200 includes a video decoding unit 201, a frame buffer 202, and a power supply clock control unit 203 that are common to 12-segment broadcasting and 1-segment broadcasting.

  The video decoding unit 201 receives the 12-segment broadcast video stream data held in the stream buffer 104 and the 1-segment broadcast video stream data held in the stream buffer 111 as input, and is instructed by an instruction from the control unit 115. A decoding function is provided for both 12-segment broadcast and 1-segment broadcast video stream data for decoding stream data and outputting the decoded video data to the frame buffer 202.

  The video decoding unit 201 needs to support decoding of video stream data of 1 segment broadcast in addition to video stream data of 12 segment broadcast. This is because the standard is different between the moving image compression / decompression standard (MPEG-2) of the video stream data of 12 segment broadcast and the moving image compression / decompression standard (H.264) of the video stream data of 1 segment broadcast. As one of the realization configurations of such a video decoding unit 201, a dedicated circuit or DSP capable of programmably supporting the processing of parts different in each standard, and a dedicated circuit for processing a common processing part A circuit composed of:

  The frame buffer 202 holds video data of 12 segment broadcast and 1 segment broadcast decoded by the video decoding unit 201. The power supply clock control unit 203 controls the operating frequency of the video decoding unit 201 according to an instruction from the control unit 115, and controls the power supply voltage in conjunction with the operating frequency.

  Then, the display output unit 114 selects the 12-segment broadcast video data held in the frame buffer 202 or the broadcast-side video data instructed from the control unit 115 from the 1-segment broadcast video data, and sends it to the external display device. Image processing such as enlargement / reduction processing, rotation processing, and high image quality processing necessary for output is executed and output to the LCD 116.

  The operation of the digital broadcast receiving apparatus 200 according to the second embodiment configured as described above will be described with reference to the drawings. Here again, the operation of the digital broadcast receiving apparatus 200 according to the present embodiment will be described with a focus on differences from the first embodiment. That is, unless specifically mentioned here, the operation of the digital broadcast receiving apparatus 200 of the present embodiment is the same as that of the first embodiment.

  In the digital broadcast receiving apparatus 200 of the second embodiment, compared to the first embodiment, 12 segment broadcast reception output processing, 1 segment broadcast reception output processing, switching processing from 12 segment broadcast to 1 segment broadcast, A difference occurs in a part of the processing flow of the switching process from 1 segment broadcast to 12 segment broadcast. Therefore, each process in the present embodiment will be described below.

(12 segment broadcast reception output processing)
First, the 12-segment broadcast reception output process will be described with reference to FIG. FIG. 10 is a diagram showing a processing flow of 12 segment broadcast reception output processing. In this 12-segment broadcast reception output process, the clock and power supply voltage of the common video decoding unit 201 are set within a range necessary for the normal playback process of the 12-segment broadcast (S211). Then, the 12-segment tuner 101, the 12-segment demodulation unit 102, the 12-segment demultiplexing unit 103, and the video decoding unit 201 are activated to perform reception and decoding (S212), and the decoded frame of the video decoding unit 201 is displayed on the display output unit 114. Is output to the LCD 116 (S213).

  1 segment tuner 107, 1 segment demodulator 108, 1 segment demultiplexer 109, I frame detector 110, and stream buffer 111 are receiving and outputting 12 segment broadcasts in preparation for switching from 12 segment broadcasts to 1 segment broadcasts. Also make it work. Then, the 1-segment tuner 107, the 1-segment demodulation unit 108 and the 1-segment demultiplexing unit 109 receive the stream data of the same program as the 12-segment broadcast program and store it in the stream buffer 111 (S214).

(1 segment broadcast reception output processing)
Next, the one-segment broadcast reception output process will be described with reference to FIG. FIG. 11 is a diagram illustrating a process flow of the one-segment broadcast reception output process. In this one-segment broadcast reception output process, the clock and power supply voltage of the common video decoding unit 201 are set within a range necessary for the normal reproduction process of the one-segment broadcast (S221). Then, the 1-segment tuner 107, the 1-segment demodulation unit 108, the 1-segment demultiplexing unit 109, and the video decoding unit 201 are activated to receive and decode (S222), and the decoded frame of the video decoding unit 201 is displayed on the display output unit 114. To the LCD 116 (S223).

  At this time, if the 12-segment tuner 101 is stopped, the 12-segment tuner 101 is activated (S224), receives the broadcast wave of the 12-segment broadcast, measures the electric field strength, and recovers the reception quality of the 12-segment broadcast to a predetermined quality or higher. To detect.

  In this case, since the 12-segment broadcast is not output, the power supply clock control unit 117 and the power supply clock control unit 118 cut off the power of the 12-segment demodulation unit 102, the 12-segment demultiplexing unit 103, and the I frame detection unit 110, or stop the clock. In this way, an instruction is output from the control unit 115. In this way, the 12-segment demodulation unit 102, the 12-segment demultiplexing unit 103, and the I frame detection unit 110 are shifted to the low power mode (S225).

(Switching from 12-segment broadcasting to 1-segment broadcasting)
FIG. 12 is a diagram showing a processing flow of switching processing from 12-segment broadcasting to 1-segment broadcasting. As shown in FIG. 12, when the switching process from 12-segment broadcasting to 1-segment broadcasting is started, the clock and power supply voltage of the common video decoding unit 201 are maximized and high-speed decoding processing is performed on the video stream of one-segment broadcasting. (S231).

  When the high-speed decoding process by the video decoding unit 201 is executed and a displayable frame after switching is detected (S232), the frame output from the display output unit 114 to the LCD 116 is stored in the frame buffer 202. The broadcast frame data is switched to the switched one-segment broadcast display frame data stored in the frame buffer 202 (S233).

  Next, the one-segment broadcast decoding process of the video decoding unit 201 is changed to the process at the normal frame rate (S234), and the clock and the power supply voltage of the video decoding unit 201 are reduced within the range necessary for the normal reproduction process of the one-segment broadcasting. (S235). Then, the process of the I frame detection unit 110, which is an unnecessary process in the one-segment broadcast reception output process, is stopped. (S236).

(Switching from 1-segment broadcasting to 12-segment broadcasting)
FIG. 13 is a diagram illustrating a processing flow of switching processing from 1-segment broadcasting to 12-segment broadcasting. As shown in FIG. 13, when the switching process from the 1-segment broadcasting to the 12-segment broadcasting is started, the low power mode of the 12-segment demodulation unit 102 and the 12-segment demultiplexing unit 103 is canceled and activated (S241).

  Thereafter, the clock and power supply voltage of the video decoding unit 201 are set within a range necessary for normal reproduction processing of 12-segment broadcasting, and reception / decoding is executed (S242). Then, it waits until a decoded frame is output from the video decoding unit 201 (S243), and when the frame data after display switching is output, the display output from the display output unit 114 to the LCD 116 is transmitted from 1 segment broadcasting to 12 segment broadcasting. (S244).

  In the first embodiment, a video decoding unit 105 that decodes video stream data of 12-segment broadcasting and a video decoding unit 112 that decodes video stream data of 1-segment broadcasting are separately provided. The digital broadcast receiving apparatus 200 according to the embodiment includes a common video decoding unit 201 that can handle both 12-segment broadcast and 1-segment broadcast video stream data.

  Therefore, in the 12-segment broadcast reception output process, the 1-segment broadcast reception output process, and the switching process between the two broadcasts, in the first embodiment, the two video decoding units 105 and 112 are powered according to the processing scene. In contrast to realizing low power consumption by blocking or stopping the clock, in the digital broadcast receiving apparatus 200 of the second embodiment, the common video decoding unit 201 has the necessary processing performance according to the processing scene. Low power is achieved by reducing the clock operating frequency and power supply voltage.

  The video stream data for 12-segment broadcast and the video stream data for 1-segment broadcast have different video compression / decompression standards, but the 12-segment broadcast video stream data is decoded due to the difference in screen resolution and frame rate. However, higher processing performance is required than the decoding processing of video stream data of one segment broadcasting. Therefore, when normal playback processing of video stream data of 1 segment broadcast is performed, the clock and power supply voltage of the video decoding unit 201 can be reduced compared to when normal playback processing of video stream of 12 segment broadcast is performed.

  Such a digital broadcast receiving apparatus 200 according to the second embodiment of the present invention also provides the same effects as those of the first embodiment.

  In this case, the video decoding unit 201 common to 12-segment broadcasting and 1-segment broadcasting can share components and share space, thereby reducing the cost and size of the apparatus.

  The embodiments of the present invention have been described above by way of example, but the scope of the present invention is not limited to these embodiments, and can be changed or modified in accordance with the purpose within the scope of the claims. is there.

  The digital broadcast receiving apparatus of the present invention is a digital broadcast receiving apparatus having a function of receiving a plurality of stream data of a first digital broadcast and a second digital broadcast that transmit the same program at the same time. The broadcast has a transmission band set larger than that of the second digital broadcast, and the second digital broadcast has a transmission radio wave intensity set stronger than that of the first digital broadcast. The apparatus decodes the video stream data separated from the stream data of the second digital broadcast, and the first video decoding means for decoding the video stream data separated from the stream data of the first digital broadcast. The second video decoding means and the first digital broadcast according to the reception quality of the first digital broadcast, Control means for performing switching control of digital broadcasting for selecting either digital broadcasting or the second digital broadcasting as a display output; and when the first digital broadcasting is selected, the second digital broadcasting Stream holding means for holding the video stream data, wherein the first video decoding means is configured to switch the display output selection from the first digital broadcast to the second digital broadcast. The video stream data of the second digital broadcast held in the stream holding means is decoded at a higher speed than the second video decoding means.

  With this configuration, when the selection is switched from the first digital broadcast (for example, 12-segment broadcast) to the second digital broadcast (for example, 1-segment broadcast), it is retained when the first digital broadcast is selected. The second digital broadcast video stream data is decoded at a high speed by using the first video decoding means (for example, the 12-segment video decoding unit 105), so that the second digital broadcast can be changed from the first digital broadcast to the second digital broadcast. Switching to broadcasting can be performed quickly and smoothly.

  In the digital broadcast receiving apparatus of the present invention, when the first digital broadcast is selected, the second video decoding means is set to a low power mode, and the second digital broadcast is selected. And a low power mode control means for setting the first video decoding means to the low power mode.

  With this configuration, unused video decoding means (for example, the video decoding units 105 and 112) are set in the low power mode, so that power saving of the apparatus can be achieved.

  In the digital broadcast receiving apparatus according to the present invention, the stream holding unit holds at least one intra frame data included in the video stream data of the second digital broadcast.

  With this configuration, when the selection is switched from the first digital broadcast to the second digital broadcast, the second frame is used by using the intra-frame data held in the stream holding means (for example, the stream buffer 111). The decoding process of the digital broadcast video stream data can be started immediately. Therefore, switching from the first digital broadcast to the second digital broadcast can be performed quickly and smoothly.

  In the digital broadcast receiving apparatus of the present invention, the first video decoding means and the second video decoding means are decoding means common to video stream data of the first digital broadcast and the second digital broadcast. It is configured as.

  With this configuration, it is possible to share parts and share space, and it is possible to reduce the cost and size of the product.

  The digital broadcast receiving method of the present invention is a digital broadcast receiving method used in a digital broadcast receiving apparatus having a function of receiving a plurality of stream data of a first digital broadcast and a second digital broadcast that simultaneously transmit the same program. Thus, the first digital broadcast has a transmission band set larger than that of the second digital broadcast, and the second digital broadcast has a transmission radio wave intensity set stronger than that of the first digital broadcast. And the digital broadcast receiving apparatus separates the first video decoding means for decoding the video stream data separated from the first digital broadcast stream data and the second digital broadcast stream data. Second video decoding means for decoding the received video stream data, The digital broadcasting receiving method performs switching control of digital broadcasting for selecting one of the first digital broadcasting and the second digital broadcasting as a display output according to the reception quality of the first digital broadcasting, When the first digital broadcast is selected, the video stream data of the second digital broadcast is held, and the display output selection is switched from the first digital broadcast to the second digital broadcast. In some cases, the first video decoding means is used to decode the video stream data of the second digital broadcast held in the stream holding means at a higher speed than the second video decoding means.

  According to this method, when the selection is switched from the first digital broadcast to the second digital broadcast, the image of the second digital broadcast held when the first digital broadcast is selected. By switching the stream data at a high speed using the first video decoding means, the switching from the first digital broadcast to the second digital broadcast can be performed quickly and smoothly.

  As described above, the digital broadcast receiving apparatus according to the present invention has an effect that the switching from the first digital broadcast to the second digital broadcast can be performed quickly and smoothly. It is useful for portable terminals such as portable navigation devices and in-vehicle navigation devices.

The block diagram which shows the structure of the digital broadcast receiver in 1st Embodiment Illustration of frame sequence of video stream data of 1 segment broadcasting Flow chart of digital broadcast reception processing in the first embodiment Flow chart of 12-segment broadcast reception output processing in the first embodiment Flow chart of 1-segment broadcast reception output processing in the first embodiment Flow chart of reception output impossibility notification processing in the first embodiment Flow chart of broadcast switching processing from 12-segment broadcasting to 1-segment broadcasting in the first embodiment Flow chart of broadcast switching processing from 1-segment broadcasting to 12-segment broadcasting in the first embodiment The block diagram which shows the structure of the digital broadcast receiver in 2nd Embodiment Flow chart of 12-segment broadcast reception output processing in the second embodiment Flow chart of 1-segment broadcast reception output processing in the second embodiment Flow diagram of broadcast switching processing from 12-segment broadcasting to 1-segment broadcasting in the second embodiment Flow diagram of broadcast switching processing from 1-segment broadcasting to 12-segment broadcasting in the second embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Digital broadcast receiver 101 12 segment tuner 102 12 segment demodulation part 103 12 segment demultiplexing part 104 Stream buffer 105 12 segment video decoding part 106 Frame buffer 107 1 segment tuner 108 1 segment demodulation part 109 1 segment demultiplexing part 110 I frame Detection unit 111 Stream buffer 112 1 segment video decoding unit 113 Frame buffer 114 Display output unit 115 Control unit 116 Liquid crystal display (LCD)
117 to 122 Power clock control unit 200 Digital broadcast receiver 201 Video decoding unit 202 Frame buffer 203 Power clock control unit

Claims (5)

A digital broadcast receiving apparatus having a function of receiving a plurality of stream data of a first digital broadcast and a second digital broadcast that simultaneously transmit the same program,
The first digital broadcast has a transmission band set larger than that of the second digital broadcast, and the second digital broadcast has a transmission radio wave intensity set stronger than that of the first digital broadcast. ,
The digital broadcast receiving apparatus includes:
First video decoding means for decoding video stream data separated from the stream data of the first digital broadcast;
Second video decoding means for decoding video stream data separated from the stream data of the second digital broadcast;
Control means for performing switching control of the digital broadcast for selecting one of the first digital broadcast and the second digital broadcast as a display output according to the reception quality of the first digital broadcast;
Stream holding means for holding video stream data of the second digital broadcast when the first digital broadcast is selected;
With
The first video decoding means includes:
When the display output selection is switched from the first digital broadcast to the second digital broadcast, the video stream data of the second digital broadcast held in the stream holding means is converted into the second video. A digital broadcast receiver characterized in that decoding processing is performed at a higher speed than the decoding means.   When the first digital broadcast is selected, the second video decoding means is set to a low power mode, and when the second digital broadcast is selected, the first video decoding means 2. The digital broadcast receiving apparatus according to claim 1, further comprising low power mode control means for setting the power to a low power mode.   3. The digital broadcast receiving apparatus according to claim 1, wherein the stream holding unit holds data of at least one intra frame included in the video stream data of the second digital broadcast.   The first video decoding means and the second video decoding means are configured as decoding means common to video stream data of the first digital broadcast and the second digital broadcast. The digital broadcast receiver according to any one of claims 1 to 3. A digital broadcast receiving method used in a digital broadcast receiving apparatus having a function of receiving a plurality of stream data of a first digital broadcast and a second digital broadcast that simultaneously transmit the same program,
The first digital broadcast has a transmission band set larger than that of the second digital broadcast, and the second digital broadcast has a transmission radio wave intensity set stronger than that of the first digital broadcast. ,
The digital broadcast receiving apparatus includes: a first video decoding means for decoding video stream data separated from the first digital broadcast stream data; and a video stream separated from the second digital broadcast stream data. A second video decoding means for decoding the data;
The digital broadcast receiving method includes:
In accordance with the reception quality of the first digital broadcast, the digital broadcast switching control is performed to select either the first digital broadcast or the second digital broadcast as a display output,
When the first digital broadcast is selected, hold the video stream data of the second digital broadcast,
When the display output selection is switched from the first digital broadcast to the second digital broadcast, the second digital broadcast held in the stream holding means by using the first video decoding means. A digital broadcast receiving method characterized in that the video stream data is decoded at a higher speed than the second video decoding means.

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