JP2006174209A - Digital broadcast receiving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a digital broadcast receiving device which is capable of avoiding a state where images are not displayed as much as possible when the receiving device starts receiving broadcast again after it stops receiving broadcast or the receiving device switches the channel from one to the other. <P>SOLUTION: Images are not possibly displayed on the screen of a display unit 36 when an IDR frame can not be acquired because the state of radio wave reception gets worse, but in this invention, when the received images can not be displayed on the screen because the state of radio wave reception gets worse, a CPU 13 reads out image data stored in a memory 14 and gives them as an IDR frame to an AV decoder 4. The AV decoder 4 outputs the above image data as the decoded image data (the above image data are displayed on the display unit 36), and when data which are newly received in a reception-possible state are a non_IDR frame, images are produced resting on a difference between the non_IDR frame and the above image data. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a digital broadcast receiving apparatus that receives terrestrial digital broadcasts.

In the digital terrestrial broadcasting service, a one-segment service for mobile bodies such as mobile phones is planned. In digital broadcasting, it takes a relatively long time for a received video to be displayed at the time of channel switching. However, attempts have been made to solve such problems (see Patent Documents 1 and 2).
JP-A-10-190617 JP 2000-295540 A

  By the way, as the video encoding method of the one-segment service described above, H.264 is used. H.264 will be adopted. In this encoding method, since IDR frames necessary for video decoding are inserted at intervals of 2 to 5 seconds, it takes time to start video display at the time of reception recovery after a broadcast wave reception interruption or channel switching. Is expected to take.

  In view of the above circumstances, the present invention provides a digital broadcast receiver capable of avoiding a video non-display state as much as possible at the time of reception recovery after a broadcast wave reception is interrupted or at the time of channel switching. Objective.

  In order to solve the above problems, the digital broadcast receiving apparatus of the present invention generates a stream by demodulating the received terrestrial digital broadcast wave, and refers to the independent frame that can be decoded by itself and the independent frame. A digital broadcast receiver configured to generate an associated frame group that can be decoded and generate the video data by decoding the frame, and includes means for outputting the video data held in the memory When the broadcast reception function is activated, when the reception condition of the broadcast wave deteriorates, and when at least one of the video display disabled periods occurs at the time of channel switching, and when it is the accompanying frame that can be newly received after that, Video decoding is performed using the associated frame and the video data stored in the memory. Characterized in that it is (hereinafter, referred to as a first configuration in this section).

  In the case of the first configuration, when the video display disabled period occurs and a newly received frame can be received after that, a video is generated based on the frame and the video data held in the memory. Since the decoding is performed, the user sees that the video based on the video data held in the memory gradually changes on the screen, and the video non-display state is avoided as much as possible.

  In the digital broadcast receiving apparatus having the first configuration, the held video data is single color video data, repetitive pattern video data, video data indicating that reception is not possible, or any video data selected by a user. Is good.

  Alternatively, the digital broadcast receiving apparatus having the first configuration includes means for temporarily storing the latest received video in a memory, and the stored video data is temporarily stored in the memory. The latest received video may be used (hereinafter referred to as the second configuration in this section). In the second configuration, the means for temporarily storing the latest received video in the memory is configured to hold the latest received video for a plurality of channels, and the latest held for the selected channel. The received video may be used for decoding.

  In the digital broadcast receiving apparatus of the first configuration, a network connection function for accessing a server that provides the latest video in the broadcast video and acquiring the latest video, and temporarily storing the latest acquired video in the memory And the stored video data may be the latest acquired video temporarily stored in the memory (hereinafter referred to as a third configuration in this section). In the third configuration, the means for temporarily storing the latest acquired video in the memory is configured to hold the latest acquired video for a plurality of channels, and the latest stored for the selected channel. The acquired video may be used for decoding.

  In the first configuration and the subordinate configuration, means for temporarily storing the latest received video by broadcast reception or the latest acquired video obtained by network connection in the second memory and the display of the received video are disabled. Means for measuring the time from the time point, and when the received video image becomes in a receivable state within a predetermined time after the received video image cannot be displayed, the video data read from the memory is not stored in the second memory. It may be configured to perform video decoding based on the latest received video held or the latest acquired video and the accompanying frame.

  Means for outputting video data held in the second memory in the second configuration and the third configuration and subordinate configurations thereof; means for measuring the time from when the received video cannot be displayed; and When the received video is in a state in which the received video cannot be displayed after a predetermined time has elapsed, it is held in the second memory instead of the latest received video or the latest acquired video read from the memory. The video may be decoded based on the video and the accompanying frame.

  The digital broadcast receiving apparatus having these configurations may be configured as a portable type or a mobile type that receives terrestrial digital broadcasts.

  According to the present invention, it is possible to avoid an image non-display state as much as possible at the time of reception recovery after the broadcast wave reception is interrupted or at the time of channel switching.

  A digital broadcast receiver according to an embodiment of the present invention will be described below with reference to FIGS. Here, a digital terrestrial broadcast receiver configured as a mobile phone with a TV is illustrated.

  FIG. 1 is a block diagram showing a mobile phone 10 with a TV. The mobile phone with TV 10 includes a telephone function unit 30 and a digital broadcast receiving unit 20. The telephone function unit 30 includes a control unit 31, a wireless communication unit 32, a voice processing unit 33, a memory unit 34, a key input unit (operation unit) 35, a display unit (for example, a liquid crystal panel) 36, data And a processing unit 37. The voice signal received in the normal telephone process is given to the speaker 38 via the voice processing unit 33, while the voice uttered by the user is converted into a voice signal by the microphone 39 and subjected to processing such as amplification by the voice processing unit 33. The audio signal is sent out by the wireless communication unit 32. The data processing unit 37 performs processing on the received packet. The wireless communication unit 32 performs voice and data transmission / reception processing and predetermined protocol processing (transmission time processing and reception time processing) with the base station. The control unit 31 performs overall control in the telephone function unit 30 and performs processing for cooperation with the digital broadcast receiving unit 20. For example, as a basic process, when the TV function activation key is turned on in the key input unit 35, an ON command is given to the digital broadcast receiving unit 20, and the video output from the digital broadcast receiving unit 20 is displayed on the display unit 36. A process of giving the digital broadcast receiving unit 20 a channel selection command with the number as a channel number when the numeric keypad of the key input unit 35 is operated is performed.

  The control unit 31 also functions as a mail processing unit and a Web client unit. The wireless communication unit 32 performs communication processing during operation of the Web client unit, communication processing during mail communication operation, and the like. The control unit 31 functioning as a Web client unit transmits a notation (URL or the like) specifying a method of reaching a resource existing on the Internet, and stores a file transmitted from the resource side in the memory unit 34 And processing to generate display image data by interpreting the file. The control unit 31 functioning as a mail transmission / reception unit performs a process of receiving a mail from a mail server on the Internet or transmitting a mail address and a mail text to the mail server.

  Next, the digital broadcast receiver 20 will be described with reference to FIG. The terrestrial antenna 1 gives the received signal to the terrestrial digital tuner 2. The terrestrial digital tuner 2 extracts a signal having a specific frequency from the high-frequency digital modulation signal including video / audio data. The terrestrial digital tuner 2 includes a demodulation circuit, a deinterleave circuit, an error correction circuit, etc., and demodulates the selected digital modulation signal to output a transport stream.

  The demultiplexer (DEMUX) 3 sends the transport stream to the H.264 in IEEE. H.264 video stream, audio stream, PSI / SI (Program Specific Information / Service Information), broadcast information (region identifier, service type, broadcast station identification, service number, remote control key ID), etc. The demultiplexer 3 supplies the video stream and the audio stream to the AV decoder 4 and supplies PSI / SI, broadcast information and the like (these information is called program information) to the CPU 13.

  The AV decoder 4 includes a video decoder that decodes a video stream and an audio decoder that decodes an audio stream. The video decoder decodes an input encoded signal to obtain a quantization coefficient and a motion vector, and performs inverse DCT transform, motion compensation control based on the motion vector, and the like. The audio decoder decodes the input encoded signal to generate audio data. The video data generated by the decoding is output to the frame buffer memory 5, and the audio data is output to the audio processing circuit 6.

  The frame buffer memory 5 receives the latest video data for one frame from the AV decoder 4 and supplies it to a drawing memory (VRAM) 7. The contents of the drawing memory 7 are displayed on the display unit 36. The audio processing circuit 6 receives the audio data output from the AV decoder 4 and performs D / A conversion to generate, for example, a right (R) sound analog signal and a left (L) sound analog signal. These audio signals are supplied to the speaker 38 or a speaker (not shown) provided separately from the telephone.

  A memory (for example, RAM, EEPROM, flash memory, etc.) 14 stores a channel table (a channel list in which frequency information, broadcast station name, etc. are associated with remote control key IDs and channel numbers) and the like. The memory 14 stores video data (still video data). This video data is single color video data (for example, video data of white, black, gray, blue, etc.), repeated pattern video data (for example, checkered pattern, stripe pattern, diagonal stripe pattern, etc.) or cannot be received. Video data (message image or graphic) indicating the user, etc., arbitrary video data selected by the user (video selected from the video downloaded by the user, or video taken by the user if the camera function is provided) It is.

  The CPU 13 has an OSD (On Screen Display) function, and writes video data based on character information and color information into the drawing memory 7. In addition, the CPU 13 reads out the video data stored in the memory 14 and gives it to the AV decoder 4 as an IDR frame (described later). The CPU 13 exchanges information with the telephone function unit 30 via the external input / output interface 9. Further, the CPU 13 can perform channel search processing by the digital broadcast receiving unit 20 and channel selection processing using the search result (channel table).

  By the way, in terrestrial digital broadcasting, as described above, broadcast data is composed of a transport stream (Transport Stream) made up of fixed-length data called a transport stream packet (Transport Stream Packet). Each TS packet is assigned a PID based on data such as video data and audio data, and the demultiplexer 3 separates the data based on the PID.

  In terrestrial digital broadcasting for mobile phones, the video encoding method is IEEE H.264. H.264 is adopted. H. H.264 includes an IDR frame (independent frame) and a non_IDR frame (accompanying frame). It is guaranteed that decoding can be performed normally when decoding from the IDR frame, and the IDR frame must be reliably decoded. become.

  If the received radio wave condition deteriorates and the IDR frame cannot be acquired, nothing may be displayed on the screen of the display unit 36. When the received video cannot be displayed due to deterioration (when the CPU 13 receives a notification that the AV decoder 4 cannot decode, a notification that the error cannot be corrected from the tuner 2, or a broadcast based on the received signal strength signal from the tuner 2) When the CPU 13 determines that the wave cannot be received, etc.), the CPU 13 reads the video data stored in the memory 14 and supplies it to the AV decoder 4 as an IDR frame. The AV decoder 4 outputs the video data as decoded video data (the video data is displayed on the display unit 36), and when it is in a receivable state and is newly received in a non_IDR frame, A video is generated by complementing the difference between the non_IDR frame and the video data (by decoding processing). As a result, if the video data is, for example, a gray-color video, immediately after the reception becomes impossible, the gray-color video is displayed on the display unit 36, and between this video and the received non_IDR frame. The video based on the difference is created one after another, and the user sees the video in which the gray video gradually changes on the display unit 36.

  In the above example, video data of one gray color or the like is used for decoding, but the latest image before reception failure occurs may be used for decoding. As described above, the frame buffer memory 5 always holds the latest decoded video for one frame. Then, when reception is impossible, the CPU 13 stops writing the data generated by the AV decoder 4 to the frame buffer memory 5 according to a command from the CPU 13 (the latest decoded video (the last when the reception is disabled) Video) is displayed on the display unit 36. Thereafter, when the AV decoder 4 is in a receivable state and is newly able to receive a non_IDR frame, the AV decoder 4 is in a state incapable of receiving the non_IDR frame. Based on the difference from the last video, the video is generated (by decoding), so that when the reception is impossible, the display 36 displays the last video when the reception is impossible. At the same time, videos based on the difference between this video and the received non_IDR frame are created one after another. An image last image is gradually changed when it becomes impossible state the user will see the display unit 36.

  Further, in the case where the broadcast wave can be received within a predetermined time (for example, 1 to 2 seconds) after the reception failure occurs, it is based on the last video when the reception failure state occurs. While the display and the decoding process after the reception return using the video are performed, the display of the video data such as the above-described gray color and the video are performed when the broadcast wave can be received after the predetermined time has elapsed. You may make it perform the decoding process after the used reception return.

  FIG. 3 is a flowchart showing the contents of the above-described processing. When reception is disabled (YES in step S1), a timer (not shown) is started (step S2), and it is determined whether or not reception is possible again (step S3). When reception is possible, it is determined whether a predetermined time has elapsed (step S4), and further, it is determined whether the received frame is an IDR frame (step S5, step S8). When a non_IDR frame is received upon reception return when a predetermined time has elapsed (NO in step S5), display of video data and decoding processing using the video are performed (steps S6 and S7), and the process proceeds to step S5. When the IDR frame can be received during the repetition of step S5 to step S7 (YES in step S5), the process proceeds to step S11 and normal decoding is performed. On the other hand, when the non_IDR frame is received after the reception return that the predetermined time has not elapsed (NO in step S8), the display based on the last video and the decoding process using the video are performed (steps S9 and S10), and the process proceeds to step S8. move on. When the IDR frame can be received during the repetition of step S8 to step S10 (YES in step S8), the process proceeds to step S11 and normal decoding is performed.

  In the above-described processing, an image based on video data held in the memory 14 may be displayed for the time being on the display unit 36 when reception becomes impossible. As an image at this time, a message image or a pattern indicating that reception is not possible is preferable.

  In the above example, the last video when the reception is disabled is stored in the frame buffer memory 5, but may be stored in the memory 14. Further, the last video when the reception is disabled for each channel may be stored in the memory 14, and the last video for the selected channel may be read from the memory 14 and used.

  In the above example, the processing when the reception condition of the broadcast wave deteriorates is shown. However, the last video or the stored video data in the video display disabled period when the broadcast reception function is activated or the channel is switched. You may perform video decoding by. In such a case, the last video is preferably held for each channel. For example, when the channel is switched, the video held in the frame buffer memory 5 may be transferred and held in the memory 14 as video data of the channel (before switching).

  The last video is not limited to that obtained by broadcast reception. For example, if there is a site on the network that provides an IDR frame simultaneously with broadcasting, the IDR frame corresponding to the last video can be acquired from such a site. Specifically, a URL for connecting to the site is stored in a memory, and the control unit 31 functioning as a Web client unit acquires an IDR frame from the site by transmitting the URL over a network. Then, the data is written in the memory unit 34 or the memory 14. Further, an IDR frame in an arbitrary channel can be acquired by adding an arbitrary channel number to the end of the URL.

  In the above example, a mobile phone with a TV function has been described. However, the mobile phone may be configured as a portable or mobile digital broadcast receiver. Further, it may be a stationary terrestrial digital broadcast receiver.

It is the block diagram which showed the mobile telephone with a TV function of embodiment of this invention. It is the block diagram which showed the broadcast receiving part of the mobile telephone with a TV function of embodiment of this invention. It is the flowchart which showed the processing content of the mobile telephone with a TV function of embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Mobile phone 20 Digital broadcast receiving part 30 Telephone function part 31 Control part 32 Wireless communication part

Claims (9)

The received digital terrestrial broadcast wave is demodulated to generate a stream, and an independent frame that can be decoded by itself and an accompanying frame group that can be decoded in consideration of the independent frame are generated, and the frame is decoded. Digital broadcast receiver configured to generate video data, and includes means for outputting video data stored in the memory, when the broadcast reception function is activated, when the reception condition of the broadcast wave deteriorates, and When a video display disabled period occurs in at least one of the channels at the time of channel switching, and the newly received frame is an accompanying frame, video decoding is performed using the accompanying frame and the video data stored in the memory. A digital broadcast receiving apparatus configured to perform the above. 2. The digital broadcast receiving apparatus according to claim 1, wherein the held video data is single color video data, repetitive pattern video data, video data indicating that reception is not possible, or any video data selected by a user. A digital broadcast receiver characterized by the above. 2. The digital broadcast receiver according to claim 1, further comprising means for temporarily storing the latest received video in a memory, wherein the stored video data is the latest stored temporarily in the memory. A digital broadcast receiving apparatus characterized in that the received video is a received video. 4. The digital broadcast receiver according to claim 3, wherein the means for temporarily storing the latest received video in a memory is configured to hold the latest received video for a plurality of channels and is selected. A digital broadcast receiving apparatus characterized in that the latest received video held for a channel is used for decoding. 2. The digital broadcast receiving apparatus according to claim 1, wherein a network connection function for obtaining a latest video by accessing a server that provides the latest video in a broadcast video, and temporarily storing the latest acquired video in a memory. A digital broadcast receiving apparatus, wherein the stored video data is a latest acquired video temporarily stored in the memory. 6. The digital broadcast receiving apparatus according to claim 5, wherein the means for temporarily storing the latest acquired video in a memory is configured to hold the latest acquired video for a plurality of channels and is selected. A digital broadcast receiver configured to use the latest acquired video held for a channel for decoding. 3. The digital broadcast receiving apparatus according to claim 1, wherein means for temporarily storing the latest received video obtained by broadcast reception or the latest acquired video obtained by network connection in the second memory, and display of the received video Means for measuring the time from the time when it became impossible, and when it becomes a receivable state within a predetermined time after becoming a display impossible state of the received video, not the video data read from the memory, A digital broadcast receiving apparatus configured to perform video decoding based on a latest received video or a latest acquired video and an accompanying frame held in the second memory. 7. The digital broadcast receiving apparatus according to claim 3, wherein means for outputting video data held in the second memory and time from a point at which the received video cannot be displayed are measured. And the second received video read from the memory is not the latest received video or the latest acquired video when the received video is in a receivable state after a predetermined time since the received video is disabled. A digital broadcast receiving apparatus configured to perform video decoding based on a video held in a memory and an accompanying frame. 9. The digital broadcast receiving apparatus according to claim 1, wherein the digital broadcast receiving apparatus is configured as a portable type or a mobile type that receives terrestrial digital broadcasts.

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