JP2001346123A - Digital broadcast receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a digital broadcast receiver that displays a program that is newly designated by a user just after the user changes over a display program. SOLUTION: A storage section 12 receives a program stream whose display is designated. On the other hand, a storage section 17 stores a stream of a guide program. In the case of switching a display, a decoding section 13 reads a stream from the storage section 12 and outputs a decoding output of a program before switching until an I picture of a new program is stored in the storage section 12. A decoding section 18 applies decode processing to the program stream whose display is designated among streams of the guide program from a storage section 17. At the switching of a display program, until the decoding section 13 outputs a decoding output of a new program, a selection section 14 selects an output of the decode section 18 so that a reduced image of a new program being the output of the decoder section 18 is displayed on a slave screen on the image of the program before switching on the basis of the output of the decoding section 13. Thus, the new program can be displayed without any delay with respect to the display change-over instruction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a digital broadcast receiver for receiving and displaying an encoded stream.

[0002]

2. Description of the Related Art In recent years, BS digital broadcasting using satellites (digital satellite broadcasting) has become widespread. BS digital broadcasting is based on MPEG (Moving Picture Experts G).
The adoption of the compression technique according to Roup) 2 enables multi-channeling.

[0003] The MPEG2 standard supports multi-programs (channels), and transmits data in a transport stream (Transport Stream (TS)) in consideration of transmitting a plurality of programs in one stream. The transport stream is composed of fixed-length packets (transport packets) and includes video data, audio data, and other data.

In the MPEG2 standard, not only an I picture generated by performing encoding using only information in a frame, but also P and B generated by encoding with reference to another frame (the preceding and succeeding images). Pictures are also employed. At the time of decoding, an I picture can be decoded only by information in a frame, but a P or B picture needs to be decoded using a reference image.

[0005] Such a receiver for receiving digital broadcasting of the MPEG2 standard is disclosed, for example, in Japanese Patent Laid-Open No. 11-1 (1999).
There is a digital broadcast receiver described in JP-A-22547. This proposal reduces the non-decoding time at the time of channel switching.

When a user receives a digital broadcast signal in which a plurality of programs are multiplexed and decodes and watches a desired program, the user may change the receiving channel. In this case, the digital broadcast receiver operates until the stream of the I picture of the program specified after the user's switching instruction is input to the decoder and the decoded output is output from the decoder. Cannot be displayed.

[0007]

As described above, conventionally, in a television receiver for receiving a digital broadcast, when a user switches a display program, a stream of an I picture of a program to be newly displayed is input. However, decoding of a new program cannot be started until decoding is started, and the timing of switching the display is delayed.

The present invention has been made in view of the above problems, and provides a digital broadcast receiver capable of displaying a program specified by a user without delay immediately after the user switches the displayed program. The purpose is to do.

[0009]

SUMMARY OF THE INVENTION A digital broadcast receiver according to the present invention is a broadcast signal in which an encoded stream of a plurality of programs and a guide program created by synthesizing reduced images of the plurality of programs are multiplexed. Receiving means for separating and outputting a coded stream of each program included in the received broadcast signal, and a coded stream of a program designated for display from the receiving means, and decoding and outputting the decoded output by a decoding process. First decoding means for obtaining, a coded stream of the guide program given from the receiving means, and second decoding means for obtaining a decoded output by a decoding process; and decoding output from the first decoding means during normal display. To enable display based on the program designated for display, and when the program designated for display is switched to another program, the first decoding means Until valley decoded output of the specified program is output, it is obtained by including a selection means for enabling display based on the decoded output of the guide program from the second decoding means.

[0010] In the present invention, the receiving means receives a broadcast signal in which an encoded stream of a plurality of programs and a guide program created by synthesizing reduced images of these programs are multiplexed, and encodes each program. Separate and output the stream. The first decoding means decodes the encoded stream of the program designated for display to obtain a decoded output. The second decoding means decodes the encoded stream of the guide program to obtain a decoded output. When the display-designated program is switched to another program, the selection means sets the guide program from the second decoding means until the first decoding means outputs a decoded output of the newly designated program. To enable display based on the selected decoded output.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing a digital broadcast system including a digital broadcast receiver according to one embodiment of the present invention.

The broadcasting station 1 for digital broadcasting includes a program data encoding unit 2, a guide program generating unit 3, a packet multiplexing unit 4, and a transmitting unit 5. The program data encoding unit 2 stores program data of programs 1 to 9 (hereinafter, program 1).
Data to program 9 data).

The guide program generator 3 is also provided with program 1 data to program 9 data. The guide program generation unit 3 generates a guide program by reducing the horizontal size and the vertical size of each program from the input program 1 data to 9 data and combining them on one screen, and encodes the guide program data into program data. Output to section 2.

The program data encoding unit 2 encodes each input program data according to, for example, the MPEG2 standard, and
An encoded stream of data to program 9 data and guide program data (hereinafter referred to as program 1 stream to program 9 stream and guide program stream) is generated and output to the packet multiplexing unit 4.

The packet multiplexing unit 4 multiplexes each program stream according to the bandwidth of each program stream. For example, the packet multiplexing unit 4 multiplexes the program 1 stream as the transport stream 1, the program 2 stream and the program 3 stream as the transport stream 2, and multiplexes the program 4
Let stream be transport stream 3 and program 5
7 are multiplexed as a transport stream 4, and programs 8 and 9 and a guide program stream are multiplexed as a transport stream 5. Transport streams 1 to 5 from packet multiplexing unit 4
(Hereinafter, referred to as TS1 to TS5) are supplied to the transmission unit 5. The transmitting unit 5 adds parity for error correction to the input TS1 to TS5, further performs digital modulation suitable for a transmission path, and transmits the resultant signal as a broadcast signal.

The digital broadcast receiver 8 receives a broadcast signal via the antenna 9. The broadcast signal induced by the antenna 9 is supplied to the receiving units 10 and 15. Receiving unit 10, 1
5 is controlled by a signal from a user interface (IF) 19. The user IF 19 controls each unit based on a user operation. The receiving units 10 and 15 select a channel based on a user's selecting operation, perform digital demodulation processing, error correction processing, and the like, and then output the selected transport streams to the packet separation units 11 and 16. .

The packet separation units 11 and 16 are provided for the user I
When a user's program selection instruction is given from F19, the encoded stream of the desired program is separated from the input transport stream and output to the storage units 12 and 17, respectively. The storage units 12 and 17 are MPEG
It stores an encoded stream of a program encoded according to two standards or the like. The storage units 12 and 17 have a capacity for storing data of a plurality of frames.

In the present embodiment, the receiving unit 15
The transport stream including the guide program stream is received, and the packet separating unit 16 separates the guide program stream from the transport stream (TS5 in the example of FIG. 1) received by the receiving unit 15 and outputs the guide program stream to the storage unit 17. It has become.

In the present embodiment, when the user IF 19 issues an instruction to switch from the program being displayed to another program, the packet separating unit 11 When the I-picture is input, the data of the I-picture is output to the storage unit 12 and, at the same time, a decoding switching signal is output to the decoding unit 13.

The decoding unit 13 is controlled by the user IF 19 to read an encoded stream of a program to be displayed from the storage unit 12 and perform a decoding process. The decoded output from the decoding unit 13 is supplied to the selection unit 14. Further, in the present embodiment, even when the user instructs to switch the display program, the decoding unit 13 continues to operate until the decoding switching signal is given from the packet separation unit 11.
The decoding process of the encoded stream of the program before switching is continued, and when the decoding switching signal is input, the user IF 19 specifies the address of the storage unit 12 in which the I picture of the program newly specified is stored. The reading of the coded stream of the program designated by the user is started to perform the decoding process.

When the decoding process of the first I picture is completed at the time of switching the display program, the decoding unit 13 outputs the decoded output to the selection unit 14 and, based on the display switching signal, determines the timing of the display switching. To be specified.

The decoding section 18 is controlled by the user IF 19 to decode the encoded stream read from the storage section 17. The decoded output from the decoding unit 18 is supplied to the selection unit 14.

In the present embodiment, the decoding unit 18
When the user IF 19 instructs to switch the display program, data corresponding to the display portion of the designated program in the guide program is read out from the storage unit 17, decoding processing is performed only on this portion, and decode output is selected. Part 14
Output. It is determined in advance which area of the guide program is to be displayed in a reduced size, and the stream corresponding to the reduced screen of each program is stored in any area of the storage unit 17. The decoding unit 18 is able to recognize whether or not the data is stored in the.

The selection section 14 is controlled by a display switching signal from the decoding section 13 to selectively output the decoded outputs of the decoding sections 13 and 18. For example, the selection unit 14 outputs a low level (hereinafter, “L”) of the display switching signal.
), Only the decoded output of the decoding unit 13 is selected, and the decoded output of the decoding units 13 and 18 is selected at the high level of the display switching signal (hereinafter, referred to as “H”). Decoding unit 13,
The decoding output of the decoding unit 18 is equivalent to a screen image, and the selection unit 14 switches the decoding output in synchronization with the horizontal and vertical synchronization signals, thereby displaying the decoding output of the decoding unit 18 on the screen based on the decoding output of the decoding unit 13. A reduced screen based on the decoded output can be displayed on a small screen.

The decode output from the selector 14 is displayed on the display 2
0 is supplied. The display unit 20 projects a program based on the decoded output.

Next, the operation of the embodiment configured as described above will be described with reference to FIGS. FIG. 2 is an explanatory diagram for explaining a guide program, FIG. 3 is a timing chart for explaining the operation of the embodiment, and FIG. 4 is an explanatory diagram for explaining a screen display when a display program is switched. It is. FIG. 3A shows a display program designation signal from the user IF 19, FIG. 3B shows an output of the packet separation unit 11, FIG. 3C shows a decoding switching signal,
FIG. 3D shows the display switching signal, and FIG. 3E shows the contents of the storage unit 12. 4 (a) to 4 (c) show screen displays before the switching of the displayed program, during the switching of the displayed program, and after the switching of the displayed program is completed, respectively. "Indicates that images of programs 1 and 6 are displayed, respectively.

In the digital broadcasting station 1, the program data of the programs 1 to 9 is supplied to the guide program generation unit 3, and the program size of the guide program is reduced and combined to reduce the horizontal size and the vertical size of each program. Data is generated.

FIG. 2 shows a screen display of the guide program. The programs 1 to 9 are reduced, combined and displayed on one screen. The programs of each of the programs 1 to 9 are displayed in the areas indicated by “program 1” to “program 9” in FIG.

The program 1 to program 9 data and the guide program data are encoded by the program data encoding unit 2, and the program 1 stream to the program 9 stream and the guide program stream are output to the packet multiplexing unit 4. The packet multiplexing unit 4 multiplexes the input streams by using TS1 to TS5 as shown in FIG. The transmitting unit 5 transmits TS1 to TS5 as broadcast signals.

The broadcast signal is received by the antenna 9 of the digital broadcast receiver 8. The high-frequency signal from the antenna 9 is supplied to the receiving units 10 and 15, and a channel is selected based on a user's selecting operation.

Now, it is assumed that the user wants to view program 1. The receiving unit 10 selects a TS1 including the program 1 data according to an instruction from the user IF 19 and outputs the selected TS1 to the packet separating unit 11. The packet demultiplexing unit 11
The program 1 data is output to the storage unit 12. Decoding unit 13
Reads the program 1 data from the storage unit 12 and performs a decoding process. The decoding output from the decoding unit 13 is output to the selection unit 14
Is displayed on the display screen of the display unit 20 as shown in FIG.
As shown in (a), an image of program 1 is displayed.

On the other hand, in the present embodiment, the receiving unit 1
Numeral 5 selects the TS 5 including the guide program stream and outputs the selected channel to the packet separating unit 16. Packet separator 16
, Separates the guide program stream from the input TS5 and outputs it to the storage unit 17.

Here, it is assumed that the user performs an operation of switching the displayed program from program 1 to program 6. Based on a user operation, a display program designation signal shown in FIG. 3A is supplied from the user IF 19 to each unit. Program 6 as display program
Is input to the receiving unit 10 and the packet separating unit 11, the receiving unit 10 tunes in to TS 4 including the program 6 stream, and the packet separating unit 11
Separates the six streams of the program in TS4. FIG.
As shown in (b), the program 6 stream is supplied to and stored in the storage unit 12 slightly after the designation by the display program designation signal.

In the example shown in FIG. 3, immediately after the display program switching signal is instructed by the display program designation signal, the program 6 stream is input to the storage unit 12 in the order of B picture, P picture, B picture, I picture,. It is memorized. FIG.
(E) shows a change in the storage content of the storage unit 12, and immediately after the switching of the program by the display program designation signal, the storage unit 1
The data in 2 gradually changes into 6 streams of the program. Since the storage unit 12 has a storage capacity of a plurality of frames,
A predetermined period after the storage of the program 6 stream is started,
Data necessary for displaying the program 1 remains in the storage unit 12.

On the other hand, when the display program is switched by the user, the display switching signal shown in FIG. 3D immediately goes high (hereinafter referred to as "H"). Then, the selection unit 14 selects the output of the decoding unit 18 at the timing corresponding to, for example, the lower right area of the display screen of the display unit 20,
At another timing, the output of the decoding unit 13 is selected. The decoding unit 13 continues the decoding process of the program stream before the display program switching is specified during the “H” period of the display switching signal, so that the program 1 is displayed even after the display of the program 6 is specified by the display program specifying signal. Is output from the selection unit 14 to the display unit 20.

On the other hand, when a display program designation signal indicating switching to the program 6 is input, the decoding unit 18 reads data corresponding to the program 6 from the storage unit 17 and decodes the data.
The selection unit 14 selects the output of the decoding unit 18 at a timing corresponding to the lower right area of the display screen. Therefore, during the “H” period of the display switching signal, the selection unit 14 outputs the program 1
And the decoded output of program 6. Thus, on the display screen of the display unit 20, a small screen display in which the program 6 is reduced and displayed in the lower right area of the program 1 is displayed as shown in FIG.

As shown in FIG. 3, the decoding section 13 sets the display switching signal to "H" at the same time that the switching instruction of the program 1 to the program 6 is generated by the display program specifying signal, and the user switches to the program 6. Immediately after the instruction of FIG.
Can be displayed on the small screen of the program 6 shown in FIG.

The packet separation unit 11 first stores the I picture after switching to the program 6 by the display program designation signal.
, And outputs a decoding switching signal to the decoding unit 13 at the same time. Thereby, the decoding unit 13 reads the I picture of the program 6 from the storage unit 12 and starts the decoding process. When the decoding process of the I picture is completed, the decoding unit 13
Outputs the decode output of the program 6 to the selection unit 14 and returns the display switching signal to "L".

Then, the selector 14 selects only the output of the decoder 13 and supplies it to the display 20. As a result, the program 6 is displayed on the display screen of the display unit 20 as a full screen as shown in FIG.

As described above, in the present embodiment, it is possible to reduce the size of the program designated for display by using the guide program, and to display the small screen immediately after the user switches the displayed program. However, the image of the newly designated program can be projected on the screen.

It should be noted that after a program switching instruction, a new program I
Before the picture is stored in the storage unit 12, if the stream of the previous program stored in the storage unit 12 is not stored by the amount of data necessary for decoding, the program 1 of FIG. The display area will be blacked out.
In other words, if there is no need to display the program before switching after the program switching instruction, the storage unit 12 is unnecessary.
In addition, the position where the newly specified program is displayed in the sub-screen is
If it is not necessary to define the storage, the storage unit 17 can be omitted.

FIG. 5 is a block diagram showing another embodiment of the present invention. 5, the same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

The embodiment of FIG. 1 shows an example in which a guide program can be displayed on one screen. But,
In recent years, the number of channels has been significantly increased, and it is conceivable that a guide program cannot be displayed on one screen. The present embodiment corresponds to this case.

The broadcast station 21 differs from the broadcast station 1 in FIG. 1 in that a guide program generator 22 is used instead of the guide program generator 3. The guide program generation unit 22 includes programs 1 to 27
Generate a guide program for. Guide program generator 2
2 is given program data of programs 1 to 27 (programs 1 to 27 data), reduces and combines the horizontal and vertical sizes of each program, and generates a guide program with reduced images of 9 programs on one screen. I do. That is, programs 1 to 27 are 3
This is combined with the guide program on the screen.

The guide program generator 22 assigns a program number to each guide program on three screens. FIG. 6 shows the guide program generator 22.
FIG. 3 is an explanatory diagram for explaining a guide program generated by the user.
For example, the guide program generation unit 22 uses the codes A, B, and C and the suffixes attached to these codes in order to distinguish each guide program on three screens. That is, the guide program generation unit 22
Assigns the symbol A to a guide program in which reduced images of programs 1 to 9 are combined, and assigns the symbol B to an id program in which reduced images of programs 10 to 18 are combined,
A guide program obtained by combining reduced images of the programs 19 to 27 is denoted by C, and these guide programs A and
B and C are sequentially generated, and are represented by subscripts in the order of generation. FIGS. 6A to 6D show guide programs A1, B1, and C1, respectively.
, A2.

The reduced images of each of the programs 1 to 27 are displayed only once every three screens of the guide program generated by the guide program generator 22. In the present embodiment, unlike the embodiment of FIG. 1, for a guide program, the program data encoding unit 2 performs only intra-frame encoding to generate an I-picture stream.

The packet multiplexing unit 4 multiplexes the input program stream. In this case, the packet multiplexing unit 4
The program number information from the guide program generation unit 22 is also multiplexed with the guide program. That is, in the example of FIG. 5, the program 27 stream, the guide program stream, and the program number information are multiplexed by the transport stream (TS10).

The digital broadcast receiver 25 differs from the digital broadcast receiver 8 of FIG. 1 in that a packet separation unit 26 and a storage unit 27 are used instead of the packet separation unit 16 and the storage unit 17, respectively. The packet separation unit 26 is controlled by the user IF 19 to separate the guide program stream included in the TS 10 and output the separated guide program stream to the storage unit 27. In the present embodiment, the packet separation unit 26 separates the program number information, and stores the storage unit 27 based on the separated program number information.
The writing area is controlled.

The storage unit 27 is controlled by the user IF 19 and stores a guide program stream. In this case, the storage unit 27 writes the guide program stream in an area corresponding to the program number. FIG. 7 is an explanatory diagram for explaining the contents stored in the storage unit 17. 7 (a) to 7
(F) shows the stored contents in the input order of the guide program stream.

In the example shown in FIG. 5, the storage unit 17 receives guide program streams A1, B1, C1, A2, B2,. The storage section 17 sequentially stores guide program streams A1, A2,..., Guide programs B1, B2,... And guide programs C1, C2,.

FIG. 7 shows images A1, B1, C1, A2, B2.
, ..., these guide program streams A1,
B1, C1, A2, B2,... Are stored. The shaded area indicates that a new guide program stream is overwritten on the area already stored.

Next, the operation of the embodiment configured as described above will be described.

The broadcast station 21 combines the reduced images of the programs 1 to 9, the programs 10 to 18, and the programs 19 to 27 in the guide program generator 22, and sequentially generates three guide program data. These guide program data are encoded by the program data encoding unit 2 and converted into an I-picture stream. The packet multiplexing unit 4
The TS10 multiplexes the guide program stream and the program number information. As described above, the program number indicates which of the three guide programs is combined with each guide program.

In the digital broadcast receiver 8, the receiving unit 10, the packet separating unit 11, the storage unit 12, and the decoding unit 13
The operation of the selector 14 is the same as that of the embodiment of FIG. The packet separating unit 26 separates the guide program stream and the program number information from the TS 10 and stores the guide program streams A, B, and
C are sequentially stored. That is, as shown in FIG. 7, the storage unit 27 has three areas, and updates and stores each area each time a guide program stream is input.

Now, it is assumed that the user performs an operation of switching the displayed program to the program 6 during reception and display of the program 1. The decoding unit 13 changes the display switching signal to “H” by a program number designation signal based on a user operation. Thus, the selection unit 14 replaces the output of the decoding unit 13 with the decoding unit 18 at the timing corresponding to, for example, the lower right area of the screen.
Selective output is output.

The decoding section 18 is controlled by the user IF 19 to sequentially read and decode the stream of the program 6 included in the streams indicated by the images A1, A2,... Among the guide program streams stored in the storage section 27. To process. The output of the decoding unit 18 is output via the selection unit 14. When the I picture of the program 6 is stored in the storage unit 12 and decoded by the decoding unit 13, the I unit
4 selects the decoded output from the decoding unit 13 and gives it to the display unit 20.

Thus, also in the present embodiment, the image of the newly designated program can be displayed as a reduced image immediately after the user issues a display program switching instruction. In addition,
Since the reduced image of each image is stored in the storage unit 27 once every three frames, the reduced image displayed on the display unit 20 is also in the state of dropped frames.

FIG. 8 is a block diagram showing another embodiment of the present invention. 8, the same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

In this embodiment, for the same program data, a stream for normal display and a stream that can be decoded in a short time when the displayed program is switched are transmitted. MPE which is a typical image compression encoding
In the case of performing encoding with emphasis on image quality in the G2 system, the data amount after encoding is set as large as possible,
It is necessary to set the length of a GOP cycle composed of I, P, and B pictures and the amount of data for each picture type to appropriate values. However, as described above, since the decoding operation of MPEG2 must always start from the I picture,
If the I-picture transmission frequency is low (the GOP cycle is long), there is a possibility that the waiting time until starting the decoding operation becomes extremely long. Therefore, a stream in which the encoding frequency of the I picture is increased is created with emphasis on shortening the decoding time.

Since the data amount of the I picture is larger than other picture types, simply increasing the coding frequency of the I picture results in a large transmission data amount. Therefore, when the encoding frequency of the I picture is increased, the encoding is performed after lowering the horizontal and vertical resolutions, so that the data amount after encoding is suppressed.

In FIG. 8, the broadcast apparatus of FIG. 1 differs from the broadcast apparatus of FIG. 1 in that the transmitting apparatus 31 eliminates the program data encoder 2 and the guide program generator 3 and employs the first encoder 32 and the second encoder 33. Different from station 1. Program data is supplied to the first encoding unit 32 and the second encoding unit 33. First encoding unit 32
Is configured to encode program data input according to, for example, the MPEG2 standard and output an encoded stream to the packet multiplexing unit 4.

The second encoder 33 also has a first encoder 33
Is supplied with the same program data as the program data input to the. The second encoding unit 33 encodes the input program such that an I picture is generated with a shorter generation period than the generation period of the I picture by the encoding process of the second encoding unit 32. For example, the second encoding unit 33 performs only intra-frame encoding on the input program data,
Only a picture may be generated.

The coded stream from the second coding unit 33 is supplied to the packet multiplexing unit 4. Packet multiplexing unit 4
Multiplexes the coded streams from the first and second coding units 32 and 33.

In the present embodiment, the second encoding unit 3
No. 3 performs encoding after reducing the input program data in order to suppress the code amount of the broadcast signal. The second
The encoding unit 33 may perform encoding after lowering the resolution of the input program data, or may reduce the code amount by increasing a quantization coefficient at the time of encoding. .

In this way, two types of encoded streams having different I-picture generation periods for the same program are multiplexed and output from the transmission device 31.

The broadcast signal received by the antenna 9 of the digital broadcast receiver 40 is supplied to the receiver 41. The receiving unit 41 selects a stream including the display program from the received signal based on a user's selecting operation and outputs the selected channel to the extracting unit 42.

The extracting section 42 extracts a program desired by the user from the input stream. The extraction unit 42 extracts the program stream encoded by the first encoding unit 32 of the transmission device 31, outputs the program stream to the first decoding unit 43, and encodes the program stream by the second encoding unit 33 of the transmission device 31. The program stream is extracted and output to the second decoding unit 44.

The first and second decoding units 43 and 44 decode the input program stream and output the decoded output to the selection unit 14. The program stream input to the first decoding unit 43 is encoded with emphasis on image quality, and the program stream input to the second decoding unit 44 generates I pictures so that the decoding start time is shortened. The encoding is performed with the period set sufficiently short.

The selection section 14 normally has the first decoding section 43
And outputs the decoded output to the display unit 20. When the display program is switched, the decoded output started first among the outputs of the first decoding unit 43 and the second decoding unit 44 is selected and output to the display unit 20. I do. When the decoding output starts to be output from the first decoding unit 43, the selecting unit 14 selects the output of the first decoding unit 43 thereafter.

The coded stream of the second coder 33 in the transmitting device 31 has a shorter I-picture generation period or is composed of only I-pictures compared to the coded stream of the first coder 32. So the second
There is a high possibility that the decoding unit 44 obtains the decoding output first immediately after the switching of the displayed program. Therefore, immediately after the switching of the displayed program, the selection unit 14 normally selects the output of the second decoding unit 44 and outputs it to the display unit 20.

At the time of switching the displayed program, the selector 14 adds the reduced image based on the output of the second decoder 44 to the still image which is the decoded output of the first decoder 43 before the switching. You may make it display on a screen.

The receiving unit 41 and the extracting unit 42 convert encoded streams of different programs of different transport streams by time division processing into the first and second decoding units 4.
3, 44 may be output.

Next, the operation of the embodiment configured as described above will be described with reference to FIGS. 9 and 10. FIG.
Is a timing chart for explaining the operation of the embodiment in FIG. 8, and FIG. 10 is an explanatory diagram for explaining the operation of the embodiment. FIG. 9A shows the output of the receiving unit 41, FIG. 9B shows the output of the second decoding unit 44, and FIG.
FIG. 9C shows the output of the first decoding unit 43, and FIG. 9D shows the output of the selection unit 14. FIGS. 10A to 10D show screen displays at the time of normal display, at the start of display program switching, during display program switching, and at the completion of display program switching, respectively. Note that "Program A" and "Program B" in FIG.
Indicates that the images of the programs A and B are displayed.

In the transmission device 31, the program data is
And the second encoding units 32 and 33. The first encoding unit 33 encodes the program data and outputs the encoded data to the packet multiplexing unit 4. On the other hand, the second encoding unit 33 includes the first encoding unit 32
For example, after reducing the same program data as the encoded program data, the I-picture generation cycle is reduced and then encoded. The coded streams from the first and second coding units 33 are multiplexed by the packet multiplexing unit 4 and transmitted by the transmitting unit 5 as broadcast signals.

The digital broadcast receiver 40 has an antenna 9
The receiver 41 selects a broadcast signal received by the receiver. Now, it is assumed that the user has instructed the display of the program A. It is assumed that program A is transmitted by transport stream 0 (hereinafter, referred to as TS0). The receiving unit 41 selects TS0 and gives it to the extracting unit 42,
The extraction unit 42 extracts the stream of the program A from TS0 and outputs the stream to the first decoding unit 43. The stream of the program A is decoded by the first decoding unit 43, and the decoded output is supplied to the display unit 20 via the selection unit 14. Thereby, the image of the program A is displayed on the screen of the display unit 20, as shown in FIG.

Here, the user inputs the timing t1 in FIG.
, An operation of designating the program B transmitted by the TS1 as the display program is performed. Then, the channel switching process is started, and the receiving unit 41
From the timing t2 in FIG. 9, TS1 is selected instead of TS0 and output is started. The extraction unit 42 extracts the program B instead of the program 1 and outputs the program B to the first and second decoding units 44. On the other hand, the selection unit 14 selects the output of the second decoding unit 44 and outputs it to the display unit 20.

In this case, the stream of the program A is not inputted to the first decoding unit 43 from the timing t 1, and the I picture data of the program B is transmitted to the first decoding unit 43 immediately after the display program is switched. Is not entered,
Immediately after the switching of the displayed program, no decoded output is output from the first decoding unit 43.

However, in the stream supplied to the second decoding unit 44, since the generation period of the I picture is set short by the second encoding unit 33, the second decoding unit 44
A relatively short time immediately after the switching of the displayed program (timing t in FIG. 9)
2), the stream of the I picture of the program B is input.

The second decoding section 44 decodes the input I picture of the program B, and decodes it at the timing t3 in FIG.
Is completed, the decoded output of the program B (decoded image b
2) is output to the selector 14. At this time, the selection unit 14
Has selected the output of the second decoding unit 44, and the output image b2 of the second decoding unit 44 is supplied to the display unit 20 and displayed.

FIG. 10C shows the display during the period from timing t3 to t4 when the decoded image b2 is a reduced image. In the period between timings t1 and t3, no decoded output is obtained from any of the first and second decoding units 43 and 44.
As shown in (b), a blackout or a still image of program A is displayed.

On the other hand, when a predetermined time has elapsed from the display program switching instruction, the I picture of the program B is also input to the first decoding unit 43. When the decoding process of the I picture ends, the first decoding unit 43 outputs a decoded output to the selection unit 14. Thereby, the selection unit 14 selects the output of the first decoding unit 43 and outputs it to the display unit 20. Thus, on the display screen of the display unit 20, the image of the program B shown in FIG.

Thus, also in the present embodiment, it is possible to reduce the waiting time required by the viewer when switching channels.

[0083]

As described above, according to the present invention, there is an effect that a program designated by a user can be displayed without delay immediately after the user switches the program to be displayed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a digital broadcast receiver according to the present invention.

FIG. 2 is an explanatory diagram for explaining a guide program.

FIG. 3 is a timing chart illustrating operation of the embodiment.

FIG. 4 is an explanatory diagram for explaining a screen display when a displayed program is switched.

FIG. 5 is a block diagram showing another embodiment of the present invention.

FIG. 6 is an explanatory diagram for explaining a guide program generated by a guide program generation unit 22.

FIG. 7 is an explanatory diagram for explaining storage contents of a storage unit 17;

FIG. 8 is a block diagram showing another embodiment of the present invention.

FIG. 9 is a timing chart for explaining the operation of the embodiment in FIG. 8;

FIG. 10 is an explanatory diagram for explaining the operation of the embodiment in FIG. 8;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Broadcasting station, 2 ... Program data coding part, 3 ... Guide program generation part, 8 ... Digital broadcast receiver, 10, 15 ... Receiving part, 11, 16 ... Packet separation part, 12, 17 ... Storage part, 13 , 18 decoding part, 14 selection part, 19 user IF, 20 display part.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) H04N 7/035 F term (reference) 5C025 AA30 BA25 BA27 CA06 DA01 DA04 5C063 AB05 AC01 AC05 CA12 CA34 DA02

Claims (6)

[Claims] 1. A broadcast signal in which an encoded stream of a plurality of programs and a guide program created by synthesizing reduced images of the plurality of programs are received, and a broadcast signal of each program included in the received broadcast signal is received. Receiving means for separating and outputting a coded stream; first decoding means for receiving a coded stream of a program designated to be displayed from the receiving means and obtaining a decoded output by a decoding process; and coding of the guide program A second decoding unit that receives a stream from the receiving unit and obtains a decoded output by a decoding process; and allows a display based on a program designated for display by selecting the decoded output from the first decoding unit during normal display. And when the program designated for display is switched to another program, the time until the first designated decoding means outputs the decoded output of the newly designated program. Selecting means for enabling display based on the decoded output of the guide program from the second decoding means. 2. The method according to claim 1, wherein, when the program designated for display is switched to another program, the second decoding means includes a stream portion corresponding to the newly designated program in the encoded stream of the guide program. 2. The digital broadcast receiver according to claim 1, wherein the digital broadcast receiver obtains a decoded output by performing decoding processing. 3. The method according to claim 1, further comprising:
Further comprising a first storage unit that supplies the intra-frame coded stream of the new program to the decoding unit even when the display-designated program is switched to another program. Until it is stored in the first storage means, the encoded stream of the program before switching held in the first storage means is decoded, and the selection means determines whether the program designated for display is another program. In the case where the program is switched to the mode, the display based on the decoded output of the program before switching from the first decoding means is performed until the decoded output of the newly designated program is output from the first decoding means. And displaying a display based on the decoded output of the guide program from the second decoding means in a sub-screen.
2. A digital broadcast receiver according to claim 1. 4. An output of said receiving means is held and said second
And a second storage unit for providing the decoding unit with the decoding unit, wherein the selection unit displays a display based on a decoding output from the second decoding unit in a predetermined area on a screen. 3. The digital broadcast receiver according to 2. 5. The method according to claim 1, wherein the guide program includes a plurality of screens, and the second storage unit includes a plurality of areas for storing the plurality of screens of the guide program. Item 3. A digital broadcast receiver according to item 2. 6. A broadcast signal including a plurality of coded streams for the same program obtained by at least two kinds of coding processes having different generation periods of intra-frame coded pictures is received, and is included in the received broadcast signal. A receiving unit that separates and outputs an encoded stream of each program; a first decoding unit that receives an encoded stream of a program whose display is designated from the receiving unit and obtains a decoded output by a decoding process; A coded stream of the same program as the program input to the decoding means, wherein the coded stream in which the intra-frame coded picture generation period is shorter than that of the coded stream input to the first decoding means. Second decoding means provided from the decoding means for obtaining a decoding output by decoding processing, and decoding from the first decoding means during normal display. Signal output is selected to enable display based on the program designated for display, and when the program designated for display is switched to another program, the first designated decoding means causes the newly designated program to be displayed. Selecting means for selecting a decoded output output earlier from the outputs of the first and second decoding means until a decoded output is output, and enabling display based on the selected decoded output. A digital broadcast receiver characterized by the following.