JP4256715B2 - Digital broadcast receiver - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to digital broadcasting that multiplexes and broadcasts a plurality of time-series information including video, audio, or various data streams, and in particular, an event criterion that serves as a reference for an event including a portion on a time axis in time-series information. Digital broadcast time synchronization method, digital broadcast transmission apparatus, digital broadcast reception apparatus, digital broadcast transmission / reception system, and digital broadcast that precisely synchronizes time and presentation reference time that is a reference for presentation time synchronization between a plurality of time-series information It relates to the data structure of broadcasting.
[0002]
[Prior art]
Recently, in addition to the existing terrestrial broadcasting, for example, the social infrastructure related to digital broadcasting has been rapidly established.
[0003]
The current digital broadcasting format in Japan employs a format that multiplexes and broadcasts a plurality of time-series information including video, audio, or various data streams. This is performed in conformity with the MPEG-2 Systems standard, which is an international standard system suitable for the above. Note that MPEG-2 Systems is defined by ISO / IEC 13818-1 which is an international standard.
[0004]
An important point to consider when receiving the time-series information transmitted in a multiplexed manner on the receiving side of the digital broadcast and restoring the video or audio stream from the received time-series information is, for example, video. The point is that the stream and the audio stream are reproduced in synchronization.
[0005]
Therefore, conventionally, on the transmission side of a digital broadcast, a so-called time stamp indicating the time to be reproduced is added to time-series information such as multiplexed video or audio stream to be transmitted, and this time stamp is also added. On the other hand, for example, a program time base reference value called PCR (Program Clock Reference) is generally added.
[0006]
The conventional time synchronization method will be described in more detail. As a time synchronization framework defined in MPEG-2 Systems, STC (System Time Clock: 42 bits, 27 MHz cycle) that functions as a time-series information presentation reference clock; A presentation time called PTS (Presentation Time Stamp: 33 bits, 90 kHz period) is prepared.
[0007]
On the other hand, EIT (Event Information) is a framework related to programs such as DVB-SI (Digital Video Broadcasting-Service Information) standardized by ETS 300 468 of the standardization organization ETS (European telecommunication Standard), that is, time synchronization of events. An event reference clock that includes the event time including the start and end times of events called the “Table: Event Information Table” and the “year / month / day / hour / minute / second” called TDT (Time and Date Table). Yes.
[0008]
According to the above conventional time synchronization method, on the receiving side of a TS (Transport Stream) including video or audio, the presentation standard transmitted in the PCR field included in the header portion in which the content identification information of the TS packet is described By presenting the presentation time PTS so as to be synchronized with the presentation reference clock STC with reference to the clock STC, it is possible to synchronize a plurality of pieces of time-series information.
[0009]
On the other hand, on the receiving side of the TS including video or audio, the event time is relatively synchronized by synchronizing the event time with the event reference clock TDT with the event reference clock transmitted in TDT as a reference. Can be defined.
[0010]
[Problems to be solved by the invention]
However, in the conventional time synchronization method, the presentation time PTS of the video or audio stream and the event time specified by EIT or the like use independent reference clocks, and further, the event reference clock TDT. Is transmitted in section format, it is difficult to accurately associate the transmission time on the sending side with the event reference clock on the receiving side. As a result, the presentation time PTS of the video or audio stream and the event specified by EIT, etc. The problem to be solved is that it is extremely difficult to achieve precise synchronization with time.
[0011]
Therefore, there has been a long-awaited expectation among related parties for the development of a new time synchronization method capable of precisely synchronizing the presentation time PTS of the video or audio stream and the event time specified by EIT or the like.
[0012]
The present invention has been made in view of the above circumstances, and serves as an event reference time that is a reference for an event including a portion on the time axis in time-series information and a reference for synchronization of presentation time between a plurality of pieces of time-series information. It is an object of the present invention to obtain a digital broadcast time synchronization method, a digital broadcast transmission device, a digital broadcast reception device, a digital broadcast transmission / reception system, and a digital broadcast data structure that can precisely synchronize the presentation reference time.
[0013]
[Means for Solving the Problems]
In order to solve the above problems, the present invention is a time synchronization method of digital broadcasting that multiplexes and broadcasts a plurality of time-series information, and when the multiplexed time-series information is transmitted from a transmission side, For an event including a portion on the time axis in the time series information, an offset between the event reference time serving as a reference of the event and the presentation reference time serving as a presentation time synchronization reference between the plurality of time series information. The gist is to precisely synchronize the presentation reference time and the event reference time on the reception side of the multiplexed time-series information by adding offset information including time and transmitting.
[0014]
According to the invention of the present invention, when the multiplexed time-series information is transmitted from the transmission side, an event reference time serving as a reference of the event for the event including the portion on the time axis in the time-series information, and a plurality of times Since the offset information including the offset time with the presentation reference time that becomes the reference of the presentation time synchronization between the time series information is added and transmitted, therefore, for example, the event time described in the EIT or the like The reference event reference time is obtained by conversion based on the presentation reference time with reference to the transmitted offset information without depending on the event reference clock TDT that is difficult to be accurately associated with. As a result of finally using the same reference time, it is possible to precisely synchronize the presentation reference time and the event reference time on the receiving side. Kill.
[0015]
The present invention is also characterized in that the multiplexing is performed in accordance with the MPEG-2 Systems standard, while the presentation reference time is given by an STC that functions as a presentation reference clock for the time-series information. To do.
[0016]
Furthermore, the present invention is a digital broadcast transmission device that multiplexes and broadcasts a plurality of time-series information, and for an event including a portion on the time axis in the time-series information, an event reference time serving as a reference for the event Offset information adding means for adding offset information including an offset time between a plurality of time-series information and a presentation reference time serving as a reference for presentation time synchronization, and offset information is added by the offset information adding means. And a transmission means for transmitting the time-series information including the event.
[0017]
According to the present invention, the offset information adding means first synchronizes the event reference time as a reference of an event and the presentation time synchronization between a plurality of time-series information for an event including a portion on the time axis in the time-series information. Offset information including an offset time between the presentation reference time serving as a reference is added. In response to this, the transmission means transmits time-series information including the event to which the offset information is added by the offset information addition means.
[0018]
Therefore, for example, the event reference time serving as a reference for the event time described in the EIT or the like is referred to the transmitted offset information without depending on the event reference clock TDT that is difficult to accurately associate, and the presentation reference In other words, the presentation reference time and the event reference time on the receiving side of the digital broadcast can be precisely synchronized as a result of using the same reference time in the end. A possible digital broadcast transmission device can be obtained.
[0019]
Furthermore, the present invention is characterized in that the multiplexing is performed in conformity with the MPEG-2 Systems standard, while the presentation reference time is given by an STC functioning as a presentation reference clock for the time-series information. And
[0020]
Moreover, the present invention is a digital broadcast receiving apparatus for receiving a digital broadcast in which a plurality of time series information is multiplexed and broadcast, and is added to an event including a portion on the time axis in the time series information. Offset information acquisition means for acquiring offset information including an offset time between an event reference time serving as a reference for the event and a presentation reference time serving as a reference for synchronizing presentation time between the plurality of time-series information; Based on the offset information acquired by the offset information acquisition means, the gist is to include time synchronization means for precisely synchronizing the presentation reference time and the event reference time.
[0021]
According to the present invention, first, the offset information acquisition means adds an event reference time, which is a reference for an event, added to an event including a portion on the time axis in time series information, and a plurality of time series information. Offset information including an offset time with a presentation reference time that is a reference for presentation time synchronization is acquired. In response to this, the time synchronization means precisely synchronizes the presentation reference time and the event reference time based on the offset information acquired by the offset information acquisition means.
[0022]
Therefore, for example, the event reference time serving as the reference of the event time described in EIT or the like is referred to the obtained offset information without depending on the event reference clock TDT that is difficult to accurately associate, and the presentation reference time A digital broadcast receiver capable of precisely synchronizing the presentation reference time and the event reference time as a result of using the same reference time in the end. Obtainable.
[0023]
The present invention is also characterized in that the multiplexing is performed in accordance with the MPEG-2 Systems standard, while the presentation reference time is given by an STC that functions as a presentation reference clock for the time-series information. To do.
[0024]
Furthermore, the present invention is a digital broadcast receiving apparatus for receiving a digital broadcast in which a plurality of time series information is multiplexed and broadcast, and is added to an event including a portion on the time axis in the time series information. Offset information acquisition means for acquiring offset information including an offset time between an event reference time serving as a reference for the event and a presentation reference time serving as a reference for synchronizing presentation time between the plurality of time-series information; The gist of the invention is that it includes a time conversion means that converts the event reference time based on the presentation reference time with reference to the offset information acquired by the offset information acquisition means.
[0025]
According to the present invention, first, the offset information acquisition means adds an event reference time, which is a reference for an event, added to an event including a portion on the time axis in time series information, and a plurality of time series information. Offset information including an offset time with a presentation reference time that is a reference for presentation time synchronization is acquired. In response, the time conversion means refers to the offset information acquired by the offset information acquisition means and converts the event reference time based on the presentation reference time.
[0026]
In this way, the event reference time is converted and obtained based on the presentation reference time by referring to the offset information obtained by the offset information obtaining means. Therefore, the obtained event reference time is used as the presentation reference time. Accordingly, a digital broadcast receiving apparatus that can be precisely synchronized can be obtained.
[0027]
The present invention is also characterized in that the multiplexing is performed in accordance with the MPEG-2 Systems standard, while the presentation reference time is given by an STC that functions as a presentation reference clock for the time-series information. To do.
[0028]
Moreover, the present invention is a digital broadcast receiving apparatus for receiving a digital broadcast in which a plurality of time series information is multiplexed and broadcast, and is added to an event including a portion on the time axis in the time series information. Offset information acquisition means for acquiring offset information including an offset time between an event reference time serving as a reference for the event and a presentation reference time serving as a reference for synchronizing presentation time between the plurality of time-series information; The gist of the invention is that it includes a time conversion means that converts the presentation reference time based on the event reference time with reference to the offset information acquired by the offset information acquisition means.
[0029]
According to the present invention, first, the offset information acquisition means adds an event reference time, which is a reference for an event, added to an event including a portion on the time axis in time series information, and a plurality of time series information. Offset information including an offset time with a presentation reference time that is a reference for presentation time synchronization is acquired. In response, the time conversion means refers to the offset information acquired by the offset information acquisition means and converts the presentation reference time based on the event reference time.
[0030]
As described above, the presentation reference time is converted based on the event reference time by referring to the offset information acquired by the offset information acquisition means. Therefore, the obtained presentation reference time is used as the event reference time. Accordingly, a digital broadcast receiving apparatus that can be precisely synchronized can be obtained.
[0031]
Furthermore, the present invention is characterized in that the multiplexing is performed in conformity with the MPEG-2 Systems standard, while the presentation reference time is given by an STC functioning as a presentation reference clock for the time-series information. And
[0032]
On the other hand, the present invention includes a digital broadcast transmission device that multiplexes and broadcasts a plurality of time series information, and a digital broadcast reception device that receives the time series information multiplexed and broadcast by the digital broadcast transmission device. In the digital broadcast transmission / reception system, the digital broadcast transmission device provides a first reference for synchronization of presentation time among the plurality of time-series information with respect to an event including a portion on the time axis in the time-series information. Is transmitted with offset information describing the offset relationship between the presentation reference time exhibiting the accuracy of the event and the event reference time exhibiting the second accuracy lower than the first accuracy serving as the event reference. On the other hand, the digital broadcast receiving device refers to the offset information transmitted from the digital broadcast transmission device, based on the presentation reference time. By obtained by converting the serial event reference time, and the presentation reference time, and summarized in that to precisely synchronize with the event reference time.
[0033]
According to the present invention, the digital broadcast transmission device provides a presentation reference time that provides a first accuracy serving as a reference for presentation time synchronization between a plurality of pieces of time series information for an event including a portion on the time axis in the time series information. , And an event reference time that exhibits a second accuracy lower than the first accuracy, which is a reference for the event, is added and transmitted with offset information describing the offset relationship. By referring to the offset information transmitted from the broadcast transmission device and obtaining the event reference time based on the presentation reference time, the presentation reference time and the event reference time are precisely synchronized. It is possible to obtain a digital broadcast transmission / reception system that can precisely synchronize a given event reference time with a presentation reference time.
[0034]
The present invention also includes a digital broadcast sending device that multiplexes and broadcasts a plurality of time series information, and a digital broadcast receiving device that receives the time series information multiplexed and broadcast by the digital broadcast sending device. In the digital broadcast transmission / reception system, the digital broadcast transmission device provides a first reference for synchronization of presentation time among the plurality of time-series information with respect to an event including a portion on the time axis in the time-series information. Is transmitted with offset information describing the offset relationship between the presentation reference time exhibiting the accuracy of the event and the event reference time exhibiting the second accuracy lower than the first accuracy serving as the event reference. On the other hand, the digital broadcast receiving device refers to the offset information transmitted from the digital broadcast sending device, based on the event reference time. Wherein by obtained by converting the presentation reference time, and the presentation reference time, and summarized in that to precisely synchronize with the event reference time Te.
[0035]
According to the present invention, the digital broadcast transmission device provides a presentation reference time that provides a first accuracy serving as a reference for presentation time synchronization between a plurality of pieces of time series information for an event including a portion on the time axis in the time series information. , And an event reference time that exhibits a second accuracy lower than the first accuracy, which is a reference for the event, is added and transmitted with offset information describing the offset relationship. By referring to the offset information transmitted from the broadcast transmission device and obtaining the presentation reference time based on the event reference time, the presentation reference time and the event reference time are precisely synchronized. It is possible to obtain a digital broadcast transmission / reception system capable of precisely synchronizing the provided presentation reference time with respect to the event reference time.
[0036]
The present invention provides a data structure of a digital broadcast that multiplexes and broadcasts a plurality of time-series information, an event reference time serving as a reference for an event including a portion on the time axis in the time-series information, and the plurality The gist of the present invention is that it includes an offset information description region in which offset information including an offset time with a presentation reference time serving as a reference for presentation time synchronization between the time-series information is described.
[0037]
According to the present invention, the data structure of a digital broadcast that multiplexes and broadcasts a plurality of time-series information includes an event reference time that is a reference for an event including a portion on the time axis in the time-series information, and a plurality of time-series information. Therefore, for example, multiplexed time-series information can be stored in an offset information description area in which offset information including an offset time with a presentation reference time serving as a reference for synchronization between presentation times is described. When sending from the sending side, if the offset information is described and transmitted in the offset information description area, the event reference clock that is the reference of the event time described in the EIT or the like is difficult to accurately associate with. Without relying on TDT, it is obtained by converting based on the presentation standard time with reference to the transmitted offset information. As a result of eventually will be using the same reference time, it is possible to precisely synchronize the presentation reference time and event reference time at the receiving side.
[0038]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a digital broadcast time synchronization method, a digital broadcast transmission device, a digital broadcast reception device, a digital broadcast transmission / reception system, and a digital broadcast data structure according to the present invention will be described below in detail with reference to the drawings. .
[0039]
FIG. 1 is a schematic block diagram of a digital broadcast transmitting apparatus according to the present invention, FIG. 2 is a schematic block diagram of a first digital broadcast receiving apparatus according to the present invention, and FIG. 3 is a second block diagram according to the present invention. 4 is a schematic block diagram of a digital broadcast receiving apparatus, FIG. 4 is a diagram for explaining a digital broadcast time synchronization method according to the present invention, and FIGS. 5 to 6 describe offset information positioned as a main part of the present invention. It is a figure which shows the data structure of a PTS offset table.
[0040]
The digital broadcast transmission / reception system according to the present invention will be described by exemplifying two first and second embodiments. In the description of these embodiments, common reference numerals are used between members common to both. And a duplicate description thereof is omitted.
[0041]
First, the outline of the time synchronization method of digital broadcasting according to the present invention will be described. This time synchronization method is a time synchronization of digital broadcasting that multiplexes and broadcasts a plurality of time-series information including video, audio, or various data streams. An event reference time serving as a reference for an event for a program that includes a portion on the time axis in time-series information, that is, an event, when a multiplexed time-series information is transmitted from a transmission side, and a plurality of times The transmission reference time on the receiving side of the multiplexed time series information is transmitted by adding the offset information including the offset time between the presentation reference time that is the reference for the presentation time synchronization between the time series information of The event reference time is precisely synchronized.
[0042]
According to this time synchronization method, when the multiplexed time-series information is transmitted from the transmission side, an event reference time serving as a reference for the event, and a plurality of events including a portion on the time axis in the time-series information, Since the offset information including the offset time with the presentation reference time that is the reference for the presentation time synchronization between the time series information is added and transmitted, therefore, for example, it is described in the event information table EIT or the like. The event reference time that is the reference for the event time can be obtained by conversion based on the presentation reference time with reference to the transmitted offset information without depending on the event reference clock TDT that is difficult to accurately associate. In other words, as a result of using the same reference time in the end, It is possible to precisely synchronize the reference time.
[0043]
Next, the data structure of digital broadcasting using this time synchronization method will be described with reference to FIGS.
[0044]
The offset information POT (PTS Offset Table), that is, the PTS (Presentation Time Stamp) offset table includes, for example, an event time specified by an in-program index such as EIT, and an STC (System Time Clock: ISO / IEC11318-2). Precise time synchronization; 42 bits, 27 MHz cycle) This is information indicating the correspondence relationship, and by referring to the value of the presentation time PTS included in the PES (Packetized Elementary Stream) packet, the time with the accuracy of PTS A part on the axis, that is, a segment can be designated. Therefore, for example, it is sufficiently possible to specify a segment with accuracy of a frame which is each still image constituting a video image.
[0045]
The PTS offset table is a set of sub-tables. Further, the sub-table is a table including a correspondence between a certain event and the STC value, and includes a PTS offset section.
[0046]
Here, data items included in each field of the PTS offset section will be briefly described below with reference to FIGS.
[0047]
table_id (table identification 61): The value of this 8-bit field is used to identify the PTS offset section.
[0048]
section_syntax_indicator (section syntax instruction 63): The value of this 1-bit field must always be set to “1”.
[0049]
reserved (undefined 65, 69, 81): This field is reserved for future function expansion.
[0050]
section_length (section length 67): Of the 12-bit field value, the first 2-bit value must be “00”. The value of the section length 67 defines the number of bytes included in the section from immediately after the section_length field to the CRC (Cyclic Redundancy Check) 85 field.
[0051]
version_number (version number 71): The value of this 5-bit field indicates the version number of pts_offset_section described later. The version number 71 must be incremented by one at the modulo 32 when the information transmitted in the section is changed.
[0052]
current_next_indicator (current next instruction 73): The value of this 1-bit field must always be set to "1".
[0053]
section_number (section number 75): The value of this 8-bit field must always be set to “0x00”.
[0054]
last_section_number (last section number 75): The value of this 8-bit field must always be set to "0x00".
[0055]
event_id (event identification 79): The value of this 16-bit field is a 16-bit numerical value that identifies an event (program). The PTS offset section relates to an event (program) specified by the event identification 79.
[0056]
pts_offset (PTS offset 83): The value of this 42-bit field is specified in units of a period of 27 MHz. The value of the PTS offset 83 indicates the STC value when the time code value is “00: 00: 00: 00”.
[0057]
As described above, according to the data structure of digital broadcasting in which the present time synchronization method is used, the data structure of digital broadcasting that multiplexes and broadcasts a plurality of time-series information includes a portion on the time axis in the time-series information. It is configured to include an offset information description area in which offset information including an offset time between an event reference time serving as a reference for an event and a presentation reference time serving as a reference for synchronizing presentation time between a plurality of pieces of time-series information is described. Therefore, for example, when transmitting multiplexed time-series information from the transmission side, if the offset information is described in the offset information description area and transmitted, it becomes a reference for the event time described in the EIT or the like. Refers to transmitted offset information without depending on event reference clock TDT for which it is difficult to accurately match event reference time Therefore, the presentation reference time and the event reference time on the receiving side must be precisely synchronized as a result of using the same reference time in the end. Is possible.
[0058]
Next, a schematic configuration of the digital broadcast transmission / reception system 1 according to the first embodiment of the present invention that employs the time synchronization method will be described. As shown in FIGS. 1 and 2, the digital broadcast transmission / reception system 1 according to the first embodiment is described. The broadcast transmission / reception system 1 includes a digital broadcast transmission device 3 that multiplexes and broadcasts a plurality of time series information, and a first digital broadcast reception device 5 that receives the time series information multiplexed and broadcast by the digital broadcast transmission device 1. It is comprised including.
[0059]
The digital broadcast transmission device 3 includes an event reference clock 11, an event scheduler 13, a video storage unit 15, a presentation reference clock 17, an MPEG-2 video encoder 19, and a POT generation unit 21 that functions as an offset information adding unit. Similarly, it includes a multiplexing unit 23 that functions as an offset information adding unit and a modulation unit 25 that functions as a transmission unit.
[0060]
The event reference clock 11 has a function of outputting a Japanese standard time with 1 second accuracy, which is a reference for the event time.
[0061]
The event scheduler 13 accumulates event schedule information in which broadcast times of programs, that is, events, are described in time series. Refer to the event schedule information and the Japan standard time obtained from the event reference clock 11. Thus, for example, when a certain event reaches the broadcast start time, it has a function of outputting event start information for instructing start of broadcasting of the corresponding event.
[0062]
The video storage unit 15 includes a video tape recorder (VTR) that accumulates event contents such as dramas, for example, and has an event playback function for starting playback of the corresponding event when event start information is received from the event scheduler 13. Have.
[0063]
Note that the video storage unit 15 is used for storage-type broadcasting, such as a drama, in which an event once stored on the sending device 3 side is broadcast, and once stored on the sending device 3 side such as a live broadcast program. In the case of real-time broadcasting that broadcasts in real time without being performed, it can be omitted or passed.
[0064]
The presentation reference clock 17 has a function of outputting a presentation reference time that is a reference for presentation time synchronization between a plurality of pieces of time-series information. Specifically, the presentation reference clock 17 outputs reference time information with a sampling rate accuracy of 42 bits and 27 MHz period called STC (System Time Clock).
[0065]
The MPEG-2 video encoder 19 has a function of compressing a video stream including event contents sent from the video storage unit 15 in accordance with the MPEG-2 video standard and outputting the compressed video stream in the form of a PES packet. Yes. At this time, the presentation time PTS is added to the PES packet with reference to the presentation reference time STC sent from the presentation reference clock 17.
[0066]
When receiving the event start information from the event scheduler 13, the POT generation unit 21 refers to the presentation reference time STC sent from the presentation reference clock 17 to read and read the STC value at the moment when the event start information is received. The STC value is converted into an offset information POT format and output.
[0067]
The multiplexing unit 23 multiplexes a PES packet sent from the MPEG-2 video encoder 19 and a PES packet sent from an MPEG-2 audio encoder (not shown), and TS (Transport) obtained by this multiplexing. A program time called PCR (Program Clock Reference) obtained by referring to the offset information POT output from the POT generation unit 21 and the presentation reference time STC sent from the presentation reference clock 17 in the Stream (transport stream) packet It has a function of adding and outputting a standard reference value. The program time base reference value PCR is added to the header portion of the TS packet and transmitted, while the offset information POT is added and transmitted in a section format.
[0068]
The modulation unit 25 has a function of performing a predetermined modulation process on the TS packet sent from the multiplexing unit 23 and outputting the TS packet after the modulation process.
[0069]
On the other hand, the first digital broadcast receiver 5 includes a demodulator 31, a TS decoder 33, a PES decoder 35, a reference timer 37, an MPEG-2 video decoder 39, and a table configuration that functions as an offset information acquisition unit. The unit 41 includes a time synchronization unit and a time conversion unit 43 that functions as a time conversion unit.
[0070]
The demodulator 31 has a function of performing a predetermined demodulation process on the TS packet including the offset information POT transmitted from the digital broadcast transmission device 3 side, and outputting the demodulated TS packet.
[0071]
The TS decoder 33 extracts and outputs the program time base reference value PCR from the header part included in the demodulated TS packet sent from the demodulator 31, while the part called the payload included in the demodulated TS packet Has a function of taking out and outputting.
[0072]
The PES decoder 35 separates and extracts a plurality of pieces of time series information such as video or audio included in the payload portion transmitted from the TS decoder 33 for each type, and puts the plurality of pieces of time series information taken into respective queues. A function of accumulating and outputting a plurality of accumulated time-series information in synchronization with a predetermined reference clock STC in response to a request from the MPEG-2 video decoder 39 or an MPEG-2 audio decoder (not shown). have.
[0073]
The reference time measuring unit 37 uses a phase locking function called PLL (Phase Locked Loop), and based on the program time reference reference value PCR input from the TS decoder 33, the presentation reference time STC on the transmission device 3 side. Is accurately reproduced so that the reference clocks on the sending device 3 side and the receiving device 5 side are synchronized.
[0074]
The MPEG-2 video decoder 39 uses the presentation reference time STC reproduced by the reference timekeeping unit 37 to convert the time series information so that the STC value matches the presentation time PTS and the corresponding queue in the PES decoder 35. The time-series information extracted from the video is decompressed in accordance with the MPEG-2 video standard and output in the form of a video stream.
[0075]
The table configuration unit 41 has a function of extracting offset information POT added in a section format from the output from the PES decoder 35.
[0076]
The time conversion unit 43 refers to the offset information POT extracted by the table configuration unit 41, and based on the presentation reference time STC reproduced by the standard time measurement unit 37, for example, an event information table output from the table configuration unit 41 It has a function of converting and obtaining event times described in the EIT and outputting the obtained highly accurate event times. Specifically, the time conversion unit 43 acquires time information such as a highly accurate event time in which the time error is corrected by subtracting the offset time described in the offset information POT from the presentation reference time STC. I am doing so.
[0077]
Note that the time conversion unit 43 has an additional function when the second digital broadcast receiving device 7 cannot receive the offset information POT, and is output from the table configuration unit 41 and is defined by the DVB-SI defined TDT ( A function for obtaining time information such as event time can also be included by using an event reference clock including “year / month / day / hour / minute / second” with a precision of 1 second called “Time and Date Table”. By using this event reference clock, it is possible to designate a rough time with 1 second accuracy. In particular, when the head of an event is designated, EIT information can be used together.
[0078]
Next, a schematic configuration of the digital broadcast transmission / reception system 2 according to the second embodiment of the present invention adopting the time synchronization method will be described. As shown in FIGS. 1 and 3, the digital broadcast transmission / reception system 2 according to the second embodiment is described. The broadcast transmission / reception system 2 includes a digital broadcast transmission device 3 and a second digital broadcast reception device 7 that receives time-series information multiplexed and broadcast by the digital broadcast transmission device 1. Since the digital broadcast transmission device 3 is the same as that described in the digital broadcast transmission / reception system 1 according to the first embodiment described above, the description thereof is omitted.
[0079]
The second digital broadcast receiving apparatus 7 includes a demodulator 31, a TS decoder 33, a PES decoder 35, a reference timer 37, an MPEG-2 video decoder 39, and a table configuration unit 41 that functions as an offset information acquisition unit. A time specification unit 51, a time synchronization unit, a presentation reference time conversion unit 53 that functions as a time conversion unit, a time comparison unit 55, and a time series selection unit 57.
[0080]
Among the components of the second digital broadcast receiving apparatus 7 described above, a time designation unit 51, a presentation reference time conversion unit 53, a time comparison unit 55, and a time series selection unit that are specific to the second digital broadcast reception apparatus 7 57 will be described below.
[0081]
The time designation unit 51 is used when an operator designates an event time by numerical input or the like, and for example, a keyboard with a numeric keypad can be employed. The time designating unit 51 is used when designating an event time by selecting a desired event suitable for its own preference from among a plurality of events described in the EIT output from the table configuration unit 41. You can also.
[0082]
The presentation reference time conversion unit 53 refers to the offset information POT extracted by the table configuration unit 41, and converts and outputs the presentation reference time based on the event time designated using the time designation unit 51. have.
[0083]
The time comparison unit 55 is provided in preparation for a case where the second digital broadcast receiving device 7 cannot receive the offset information POT, and uses the event reference clock TDT output from the table configuration unit 41. Thus, it has a function of outputting the event time designated by the time designation unit 51 with an accuracy of 1 second.
[0084]
The time series selection unit 57 compares the presentation reference time obtained by the presentation reference time conversion unit 53 with the presentation time PTS included in the PES packet sent from the PES decoder 35, and the presentation time PTS is the presentation reference time. By selecting and extracting time-series information so as to match the value, for example, it has a function of cutting out a specified partial video such as a specific scene.
[0085]
In addition, when the second digital broadcast receiving device 7 cannot receive the offset information POT, the time series selection unit 57 inputs the event designation time output from the time comparison unit 55, and the input event designation time and A function of cutting out a specified partial video, for example, by comparing the presentation time PTS sent from the PES decoder 35 and selecting and extracting time-series information so that the presentation time PTS matches the event designation time. It is configured.
[0086]
Next, the general operation of the digital broadcast transmission / reception system 1 according to the first embodiment will be described. According to the digital broadcast transmission / reception system 1 according to the first embodiment, the digital broadcast transmission / reception device 3 operates on the time axis in time-series information. A presentation reference time exhibiting a first accuracy serving as a reference for presentation time synchronization between a plurality of pieces of time-series information, that is, a presentation reference time STC having a sampling rate accuracy of 42 bits and 27 MHz period, and an event The offset information POT describing the offset relationship with the event reference time exhibiting the second accuracy lower than the first accuracy is added and transmitted, while the first digital broadcast receiving device 5 Referring to the offset information POT transmitted from the digital broadcast transmission device 3, the event base is based on the presentation reference time STC. Time, for example, by obtained by converting the event time, it is possible to obtain a presentation reference time STC, the digital broadcasting transmission and reception system 1 capable of precisely synchronize the event reference time.
[0087]
On the other hand, the general operation of the digital broadcast transmission / reception system 2 according to the second embodiment will be described. The digital broadcast transmission device 3 presents an event including a portion on the time axis in time series information among a plurality of time series information. A presentation reference time exhibiting a first accuracy serving as a reference for time synchronization, that is, a presentation reference time STC having a sampling rate accuracy of 42 bits and a 27 MHz period, and a second accuracy lower than the first accuracy serving as a reference for an event. The second digital broadcast receiving device 7 refers to the offset information POT transmitted from the digital broadcast sending device 3 while adding the offset information POT describing the offset relationship with the event reference time to be transmitted. By converting the presentation reference time based on the event reference time, the presentation reference time and the event reference time are obtained. It is possible to obtain a digital broadcasting transmission and reception system 2 capable be precisely synchronized with between.
[0088]
Next, the general operation of the digital broadcast receiving apparatus 5 according to the first embodiment will be described. According to the digital broadcast receiving apparatus 5 according to the first embodiment, the MPEG-2 video decoder 39 includes the reference time measuring unit 37. The time series information is extracted from the corresponding queue in the PES decoder 35 so that the STC value coincides with the presentation time PTS using the presentation reference time STC reproduced in step S3, and the extracted time series information is converted into MPEG- The time conversion unit 43 refers to the offset information POT extracted by the table configuration unit 41 and is reproduced by the standard time measuring unit 37, while decompressing in accordance with the two video standard and outputting in the form of a video stream. For example, the event time described in the event information table EIT output from the table construction unit 41 based on the presented reference time STC Acquired by converting, it is possible to output an event time of the obtained highly accurately.
[0089]
Further, an example of the usage application of the high-precision event time output from the digital broadcast receiving device 5 according to the first embodiment will be described. For example, the video stream and the high-precision event time are, for example, the receiving device 5. In response to these inputs, the recording device starts recording the corresponding event when the designated event time arrives. As a result, it is possible to use the event for use such as recording using a highly accurate event time.
[0090]
Furthermore, the general operation of the digital broadcast receiving device 7 according to the second embodiment will be described. According to the digital broadcast receiving device 7 according to the second embodiment, the MPEG-2 video decoder 39 is a reference time measuring unit 37. Using the reproduced presentation reference time STC, time series information is extracted from the corresponding queue in the PES decoder 35 so that the STC value matches the presentation time PTS, and the extracted time series information is converted into MPEG-2. The presentation time conversion unit 53 uses the time designation unit 51 with reference to the offset information POT extracted by the table configuration unit 41 while decompressing in accordance with the video standard and outputting in the form of a video stream. Based on the specified event time, the presentation reference time is converted and output. Upon receiving this, the time series selection unit 57 obtains the presentation reference time conversion unit 53. Comparing the presentation reference time and the presentation time PTS included in the PES packet sent from the PES decoder 35, and selecting and extracting time-series information so that the presentation time PTS matches the value of the presentation reference time. Thus, the partial video specified by the time specifying unit 51 can be cut out.
[0091]
When the second digital broadcast receiver 7 cannot receive the offset information POT, the time comparison unit 55 is designated by the time designation unit 51 using the event reference clock TDT output from the table configuration unit 41. In response to this, the time series selection unit 57 compares the event designation time input from the time comparison unit 55 with the presentation time PTS sent from the PES decoder 35, By selecting and extracting time-series information so that the presentation time PTS coincides with the event designation time, the designated partial video can be cut out.
[0092]
Finally, the digital broadcast time synchronization method according to the present invention will be further described with reference to FIG.
[0093]
As shown in the figure, first, the sending device sends STC0, which is the STC value corresponding to the PTS value PTS0, when the relative time from the beginning of the event is “00: 00: 00: 00”. This value is obtained from the actual performance of the time, and this value is transmitted in the form of a PTS offset code POT with a sampling rate accuracy of 42 bits and a period of 27 MHz.
[0094]
On the other hand, for example, when the “00: 25: 42: 18” frame is designated from the top, the receiving device presents the video for the “00: 25: 42: 18” frame by the 27 MHz STC. A sum STC1 is obtained by adding the increasing value to STC0. Next, PTS1 can be obtained by converting the sum STC1 into 90 kHz PTS, and the frame corresponding to the value of PTS can be referred to.
[0095]
The PTS offset code POT is transmitted in association with each of a plurality of events. However, the PTS offset code POT is offset at regular intervals such as every day or every hour by changing to a field associated with time instead of event_id associated with the event. May be associated with each other, or may be associated as appropriate independently of the event.
[0096]
Needless to say, it can be applied to units such as scenes and cuts that are finer than events. Moreover, the PTS offset code POT can be used for both the relative time from the beginning of the event and the actual time.
[0097]
In addition, this invention is not limited to the example of embodiment mentioned above, It is possible to implement in another aspect by adding an appropriate change within the claim.
[0098]
That is, for example, in the description of the embodiment according to the present invention, a mode in which a video stream is mainly handled as time-series information has been described as an example. However, the present invention is not limited to this mode. Needless to say, the present invention can also be applied to the case where an audio stream or other data stream is handled.
[0099]
Also, the event reference clock that is the reference for the event time specified by EIT or the like does not necessarily have to be a clock that represents the current time. The operation is performed in the same manner even with a clock that represents some relative time. Therefore, according to the present invention, the event time specified by EIT or the like can be expressed by a relative time independent of the actual time.
[0100]
Further, instead of the presentation time PTS, it is also possible to use an offset with respect to a time DTS (Decode Time Stamp) at which the receiving apparatus decodes the MPEG-2 video.
[0101]
Finally, it is emphasized that the digital broadcasting time synchronization method according to the present invention is compatible with the conventional method.
[0102]
That is, if the transmitting side sends the offset information POT according to the present invention in addition to the conventional TDT, the conventional receiving apparatus can operate with the same coarse synchronization as before, and the receiving apparatus according to the present invention It is possible to operate with precise synchronization. Therefore, the PTS offset code POT has a data structure in consideration of ensuring compatibility with a receiving apparatus that does not have the function of understanding the PTS offset code POT. Furthermore, it is possible to perform flexible operations such as sending a PTS offset code POT or not sending a POT according to the synchronization accuracy required for each event.
[0103]
【The invention's effect】
According to the present invention, when the multiplexed time-series information is transmitted from the transmission side, an event reference time serving as a reference for the event and a plurality of times for an event including a portion on the time axis in the time-series information. Since the offset information including the offset time between the presentation time synchronization that is the reference of the presentation time synchronization between the sequence information is added and transmitted, therefore, for example, the event time reference described in the EIT or the like The event reference time is calculated based on the presentation reference time with reference to the transmitted offset information without depending on the event reference clock TDT that is difficult to accurately associate, As a result of using the same reference time, it is possible to precisely synchronize the presentation reference time and the event reference time on the receiving side.
[0104]
Further, according to the present invention, for example, the event reference time that becomes the reference of the event time described in the EIT or the like can be used to change the transmitted offset information without depending on the event reference clock TDT that is difficult to accurately associate. As a result, the presentation reference time and the event reference time at the receiving side of the digital broadcast are calculated as a result of using the same reference time in the end. It is possible to obtain a digital broadcast transmission device that can be precisely synchronized.
[0105]
Further, according to the present invention, for example, the event reference time that is a reference of the event time described in EIT or the like is referred to the acquired offset information without depending on the event reference clock TDT that is difficult to accurately associate. As a result, the presentation reference time and the event reference time can be precisely synchronized as a result of using the same reference time in the end. A digital broadcast receiver can be obtained.
[0106]
Furthermore, according to the present invention, the event reference time is obtained by converting the event reference time based on the presentation reference time by referring to the offset information acquired by the offset information acquisition means. Can be obtained with a digital broadcast receiver capable of precisely synchronizing with the presentation reference time.
[0107]
Moreover, according to the present invention, the presentation reference time is obtained by converting the presentation reference time based on the event reference time with reference to the offset information acquired by the offset information acquisition means. A digital broadcast receiving apparatus that can be precisely synchronized with the event reference time can be obtained.
[0108]
On the other hand, according to the present invention, the digital broadcast transmission device presents a first accuracy that serves as a reference for presentation time synchronization between a plurality of time-series information for an event including a portion on the time axis in the time-series information. While transmitting the offset information describing the offset relationship between the reference time and the event reference time exhibiting the second accuracy lower than the first accuracy, which is the event reference, the digital broadcast receiving device The presentation reference time and the event reference time are accurately synchronized by obtaining the event reference time based on the presentation reference time by referring to the offset information transmitted from the digital broadcast transmission device. Thus, a digital broadcast transmission / reception system capable of precisely synchronizing the obtained event reference time with the presentation reference time can be obtained.
[0109]
Further, according to the present invention, the digital broadcast transmission device presents a first accuracy that is a reference for presentation time synchronization between a plurality of time-series information for an event including a portion on the time axis in the time-series information. While transmitting the offset information describing the offset relationship between the reference time and the event reference time exhibiting the second accuracy lower than the first accuracy, which is the event reference, the digital broadcast receiving device Since the presentation reference time is obtained by converting the presentation reference time based on the event reference time with reference to the offset information transmitted from the digital broadcast transmission device, the presentation reference time and the event reference time are precisely synchronized. Thus, a digital broadcast transmission / reception system capable of precisely synchronizing the obtained presentation reference time with the event reference time can be obtained.
[0110]
According to the present invention, the data structure of a digital broadcast that multiplexes and broadcasts a plurality of time-series information includes an event reference time that serves as a reference for an event including a portion on the time axis in the time-series information, and a plurality of times. Since it is configured to include an offset information description area in which offset information including an offset time between the presentation reference time that is a reference for presentation time synchronization between the series information is described, for example, a multiplexed time series If the offset information is described in the offset information description area and transmitted when the information is transmitted from the transmission side, the event reference time used as the reference of the event time described in the EIT or the like is difficult to accurately associate with the event. Without depending on the reference clock TDT, it is obtained by referring to the transmitted offset information and converting it based on the presentation reference time. , I.e., it exhibited as a result eventually will be using the same reference time, an extremely excellent effect that a presentation reference time and event reference time at the receiving side can be precisely synchronized.
[Brief description of the drawings]
FIG. 1 is a schematic block diagram of a digital broadcast transmission apparatus according to the present invention.
FIG. 2 is a schematic block diagram of a first digital broadcast receiving apparatus according to the present invention.
FIG. 3 is a schematic block diagram of a second digital broadcast receiving apparatus according to the present invention.
FIG. 4 is an explanatory diagram of a digital broadcast time synchronization method according to the present invention.
FIG. 5 is a diagram showing a data structure of a PTS offset table in which offset information positioned as a main part of the present invention is described.
FIG. 6 is a diagram showing a data structure of a PTS offset table in which offset information positioned as a main part of the present invention is described.
[Explanation of symbols]
1 First digital broadcasting transmission / reception system
2 First digital broadcast transmission / reception system
3 Digital broadcast sending device
5 First digital broadcast receiver
7 Second digital broadcast receiver
11 Event reference clock
13 Event scheduler
15 Video storage
17 Reference clock
19 MPEG-2 video encoder
21 POT generation unit (offset information adding means)
23 Multiplexer (offset information adding means)
25 Modulator (Transmission means)
31 Demodulator
33 TS decoder
35 PES decoder
37 Standard timekeeping section
39 MPEG-2 video decoder
41 Table component (offset information acquisition means)
43 Time conversion unit (time synchronization means and time conversion means)
51 Time designation part
53 Presentation reference time conversion unit (time synchronization means and time conversion means)
55 Time comparison unit
57 Time series selector
61 Table identification
63 Section syntax instructions
65, 69, 81 Undefined
67 Section length
71 Version number
73 Current next instruction
75 Section number
77 Last section number
79 Event identification
83 PTS offset code
85 CRC (cyclic redundancy check)

Claims (3)

A demodulator that demodulates and outputs TS packets sent from the digital broadcast sending device side, separates a plurality of time-series information from the TS packets output from the demodulator, and serves as an event reference that serves as an event reference A digital broadcast receiver that presents video or audio according to time,
A table configuration unit that extracts and outputs offset information from a TS packet having offset information including a value of a presentation reference time corresponding to the start time of the event, and having higher accuracy than the event reference time;
A time conversion unit obtained by converting an event reference time based on a value of a presentation reference time with reference to the offset information output from the table configuration unit;
A digital broadcast receiving apparatus. A TS decoder that extracts and outputs a program time base reference value from the TS packet output from the demodulator;
Based on the program time base reference value output from the TS decoder, a reference clock unit for synchronizing the reference clock on the receiving device side with the sending device side, and outputting the reference clock to the time conversion unit;
The digital broadcast receiver according to claim 1, further comprising: The digital broadcast receiving apparatus according to claim 2, wherein the time conversion unit includes a function of obtaining an event time using an event reference clock when the offset information output from the table configuration unit is not obtained.

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