JP2003284074A - Apparatus and method for performing changeover processing of digital broadcast signal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To smoothly perform system changeover of digital broadcast signals in real time, without causing a freeze image to flap. <P>SOLUTION: When a changeover from a program of a key station to a program of a local station is performed, first of all a code quantity of a multiplexed output of a TS multiplex apparatus 12 is monitored by a changeover controller 18. When this code quantity does not exceed a reference value, a changeover by a TS changeover apparatus 17 is controlled, and the output of a TS isolating apparatus 11 which originally causes a changeover is replaced with a freeze image data train for field estimation generated from a freeze image data generator 15, to suppress the flapping of the freeze image when the changeover is performed. To prevent a broadcast band from overflowing, when the code quantity of the multiplexed output of the TS apparatus 12 exceeds the reference value, the output is replaced with a freeze image data train for a frame estimation generated by a freeze image data generator 16, and is changed over to the output of an encoder 14 to which a changeover is performed afterwards. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to, for example, a local station in net reception broadcasting, and a digital broadcasting signal switching processing device and a digital broadcasting signal switching processor for selectively deriving one of two systems of digital broadcasting signals when replacing a program. The present invention relates to a broadcast switching processing method.

[0002]

2. Description of the Related Art With the establishment of digital broadcasting technology in recent years,
Digital broadcasting has started in satellite broadcasting systems that use communication satellites and broadcasting satellites, and there is a plan to shift to digital broadcasting in terrestrial broadcasting systems.

Various developments have been made in such digital broadcasting, particularly in a parent station (hereinafter referred to as a key station) arranged in Tokyo, for example, which is implemented in the conventional analog broadcasting, and a local area. One of the challenges is to construct a net reception and broadcasting system that connects a remote station (hereinafter referred to as a local station) to be placed by a relay line.

Here, in the conventional analog broadcasting, since the signal is not compression-coded, when the program is replaced in the local station, the broadcasting signal from the key station and the broadcasting signal of the local station are frame-synchronized. , Switching by frame position was enough.

However, in digital broadcasting, broadcast data is compressed and encoded to form a stream.
Breaks are difficult to see in a compression-coded stream, and especially MPEG2 (Moving Picture Experts Group)
In video compression methods such as 2), correlation is taken between frames. Therefore, in local stations in digital broadcasting,
When replacing a program, it is not possible to simply perform frame synchronization and switch at the frame position as in analog broadcasting.

On the other hand, it is also considered that a local station in digital broadcasting adopts a method of switching to the switching destination stream after replacing the end portion of the switching source stream with an image in a frozen state when replacing a program. .

[0007]

However, when the frame prediction freezes at the time of switching, and when the image immediately before the still image part happens to be an image with a lot of movement, it freezes suddenly when this part is played back. Since it is a still image of the state, the image looks like fluttering for a moment.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a digital broadcast signal switching processing device and a digital broadcast signal switching processing method capable of smoothly switching the system of a digital broadcasting signal in real time while making the visual flutter of a frozen image inconspicuous. To provide.

[0009]

In order to achieve the above object, the present invention is configured as follows.

The present invention is applied to a digital broadcast signal transmission system that multiplexes digital broadcast signals of a plurality of systems in which a video signal of a frame structure consisting of two fields is compression-encoded and sends out as a transmission signal of a predetermined code amount, and switches among the plurality of systems. In a digital broadcast signal switching processing device for inputting two target digital broadcast signals, selectively deriving one of the digital broadcast signals in accordance with a switching signal and multiplexing the one with a transmission signal,
First image data generating means for generating a frame prediction image data sequence that is continuous with the last data in each frame of the digital broadcast signal and is necessary for stopping the motion of the image in the frame; Second image data generating means for generating a field-predicted image data sequence which is continuous with the last data in the frame and is necessary for stopping the motion of the image in the frame, the two-system digital broadcast signal, and the first And a switching means for selectively deriving at least one of the outputs of the second image data generating means as a transmission signal, and when the switching signal is input, the code amount of the output of the switching means is monitored and the code amount is Is compared with a predetermined code amount, and the switching means is switched from the switching source to one of the outputs of the first and second image data generating means in accordance with the comparison result. It is obtained by so and a switching control means for switching the replacement unit to the switching destination.

According to the present invention, at the time of switching the system, the code amount of the transmission signal is first monitored, and this code amount is compared with the predetermined code amount. From the comparison result, when the difference between the code amounts is equal to or more than the predetermined value, When the digital broadcast signal of the switching source is switched to the field-predicted still image data sequence to prevent the freeze image from fluttering at the time of switching, the code amount difference is less than a predetermined value, that is, when the field-predicted still image data sequence is switched. If there is a risk that the code amount of the transmission signal of the above will exceed a predetermined code amount, it will be switched to a frame-predicted still image data string with a smaller code amount than the field-predicted still image data string, and the system to be switched to thereafter Can be switched to the digital broadcasting signal of. Therefore, it is possible to smoothly switch the system of the digital broadcast signal in real time without causing fluttering in the frozen image as much as possible and without affecting the broadcast band.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of a digital broadcast signal transmission system applied to a local station of net reception broadcasting as an embodiment of the present invention.

This digital broadcast signal transmission system is
The S demultiplexing device 11, the TS multiplexing device 12, the local material generation device 13, the encoder 14, the freeze image data generation devices 15 and 16, the TS switching device 17, and the switching control device 18 are provided.

The TS separation device 11 separates a TS coming from, for example, a key station via a relay network and generates TS packets of a plurality of systems.

The TS multiplexer 12 re-multiplexes the TS packets of a plurality of systems separated by the TS separator 11,
A broadcast TS to be sent to the broadcast service area is generated.

The local material generator 13 generates a material signal such as a CM to be broadcast.

The encoder 14 performs variable length compression coding on the material signal output from the local material generator 13 based on the MPEG2 coding compression method, and converts it into a TS packet of MPEG2.

The freeze image data generator 15 is a TS
A freeze image data sequence of field prediction that is continuous with the last data in each frame of the TS separated by the separation device 11 and is necessary for freezing the motion of the image in the frame is generated.

The freeze image data generator 16 is a TS
The freeze image data sequence of the frame prediction that is continuous with the last data in each frame of the TS separated by the separation device 11 and is necessary for freezing the motion of the image in the frame is generated.

The TS switching device 17 selectively derives a part of the output of the TS separating device 11, each output of the freeze image data generating devices 15 and 16 and the output of the encoder 14 as an output signal to the TS multiplexing device 12. .

The switching control device 18 monitors the code amount of the broadcast TS generated by the TS multiplexer 12 and compares the code amount with the reference code amount, and the TS switching device 17 operates according to the comparison result. The connection is switched from the switching source system to one of the outputs of the freeze image data generators 15 and 16, and then switched to the switching destination system.

The processing operation of the above configuration will be described below.

The TS separation device 11 separates the TS coming from the key station, outputs the TS packet to be replaced with the program of the local station to the TS switching device 17, and the TS packets of the remaining system to the TS multiplexing device. Output to 12.

In the TS switching device 17, when the program is replaced, the output of the TS separating device 11 is controlled by the switching control of the switching control device 18, and the freeze image data generating devices 15 and 16 are output.
To selectively switch to either of the outputs. Here, the field-predicted freeze image data string output from the freeze-image data generator 15 has a larger code amount than the frame-predicted freeze image data string, but the flutter when a violently moving image is stationary is noticeable. It can be suppressed as much as possible. On the other hand, the freeze image data sequence for frame prediction output from the freeze image data generator 15 causes flutter when a moving image is stationary, but has a smaller code amount than the freeze image data sequence having the field structure. .

Therefore, in the switching control device 18, when the switching instruction signal is given, the difference between the code amount of the broadcast TS output from the TS multiplexer 12 and the reference code amount, that is, the code amount that does not overflow the broadcast band. Is greater than or equal to a predetermined value, and a switching timing signal is output to the TS switching device 17 based on the result of this determination.

Upon receiving the switching timing signal, the TS switching device 17 switches the output of the TS separation device 11, each output of the freeze image data generation devices 15 and 16, and the output of the encoder 14. The switching process of the TS switching device 17 in this case is shown in FIGS.

2A shows the output of the TS separation device 11, FIG. 2B shows the output of the encoder 14, and FIGS. 2C and 2D.
Indicates the output of the TS switching device 17, and in each figure, I is the I picture of GOP (intra-frame encoded screen), and P is P.
Picture (forward prediction screen), B indicates B picture (bidirectional prediction screen).

Here, when the difference between the code amount of the broadcast TS output from the TS multiplexer 12 and the reference code amount is less than a predetermined value, the switching control device 18, as shown in FIG. , The output of the TS separation device 11 is switched to the output of the freeze image data generation device 16.

On the other hand, if the difference between the code amount of the broadcast TS output from the TS multiplexer 12 and the reference code amount is equal to or more than a predetermined value, the switching control device 18, as shown in FIG.
The encoder 14 which is the switching destination is switched from the output of the TS separation device 11 to the output of the freeze image data generation device 15.
Until the output is switched to, the output of the freeze image data generator 16 is sequentially switched while monitoring the code amount of the output of the TS multiplexer 12 so as not to cause an overflow.

Further, the switching control device 18 connects the TS switching device 17 from the output of the TS separation device 11 to the encoder 1
When switching control to the output of 4, the output code amount of the TS switching device 17 and the output code amount of the encoder 14 are monitored and compared, and the output code amount of the TS switching device 14 and the output code amount of the encoder 14 are The TS switching device 17 is controlled so as to be continuous. That is, the switching control device 18 performs a process of inserting a stuffing byte into the output of the encoder 14 so that a seamless output signal can be obtained. The stuffing byte is composed of dummy bits of "0", and the output code amount of the TS switching device 14 and the encoder 1
4 is data generated based on the result of comparison with the output code amount of No. 4.

In this way, the signal before switching and the signal after switching are connected neatly, and the broadcasting TS can be transmitted without disturbing the information.

When executing the above processing operation, the switching control device 18 performs a control process as shown in FIG.

When this control processing is started, the switching control device 1
8 determines whether the switching instruction signal is input (step ST3a), and if the switching instruction signal is input (Yes), subsequently determines whether the field output flag is turned on. (Step ST3b). The field output flag can be arbitrarily set by the operation of the operator, and is normally set to off.

If the field output flag is off (No), the switching controller 18 prepares to select the output of the freeze image data generator 15 (step ST3c) and freezes the connection of the TS switching device 17. Switching to the output of the image data generator 15 (step ST3
d), it is determined whether or not the difference between the code amount of the output of the TS multiplexer 12 and the reference code amount is a predetermined value or more (step ST3e).

Here, if the difference between the code amount of the output of the TS multiplexer 12 and the reference code amount is more than a predetermined value (No),
The switching control device 18 controls the TS switching device 17 so as to maintain the output state of the freeze image data generation device 15 (step ST3f), sets the field output flag to ON (step ST3g), and then the above step ST3.
The processing from b to step ST3g is repeatedly executed.

Further, if the field output flag is set to ON in step ST3b,
3e, if the difference between the code amount of the output of the TS multiplexer 12 and the reference code amount is less than a predetermined value, the switching control device 1
If the field output flag is ON, 8 is set to OFF (step ST3h), and the connection of the TS switching device 17 is switched to the output of the freeze image data generating device 16 (step ST3i).

Subsequently, the switching control device 18 determines whether or not to continue the frozen image data (step ST3j), and repeatedly executes the processing of steps ST3i and ST3j until switching to the output of the encoder 14. Then, when the switching period to the output of the encoder 14 has been reached, the switching control device 18 controls the connection of the TS switching device 17 to the output of the encoder 14 (step ST3k).

As described above, in the above embodiment, when the program of the key station is replaced with the program of the local station, the switching controller 18 first monitors the code amount of the multiplexed output of the TS multiplexer 12 and the code When the difference between the amount and the reference code amount is greater than or equal to a predetermined value, the TS switching device 17 is controlled to switch the output of the TS separation device 11 that is the switching source of the field prediction generated from the freeze image data generation device 15. It is replaced with a freeze image data string to suppress the fluttering of the freeze image at the time of switching. Also, if the difference between the code amount of the multiplexed output of the TS multiplexer 12 and the reference code amount is less than a predetermined value, that is, if there is a risk of overflowing the broadcast band when replacing with a still image data string of frame prediction, freeze Replacing with a frame prediction freeze image data sequence generated from the image data generator 16,
After that, the output of the encoder 14 that is the switching destination is switched.

Therefore, the program of the key station can be replaced with the program of the local station smoothly in real time while making the freeze image visually inconspicuous and without affecting the broadcast band.

Further, in the above embodiment, if the field output flag of the switching control device 18 is turned on at the time of replacing the program, the freeze image data sequence of frame prediction automatically generated from the freeze image data generating device 16 Will be selected, and the processing load will be reduced accordingly.

Further, in the above embodiment, when the field output flag of the switching control device 18 is turned on at the time of replacing the program, this on state is displayed on the monitor, and the frozen image data is generated waiting for the instruction of the administrator. A frame-predicted frozen image data sequence generated from the device 16 may be selected. For this reason, even if the field output flag of the switching control device 18 is intentionally turned on, it is not necessary to select the frozen image data sequence for frame prediction if it is not necessary to select it at the present moment.

The present invention is not limited to the above embodiment. For example, you may make it apply to the key station of an internet reception broadcast. In this case, it is effective for replacing the program in an emergency.

Further, in the above embodiment, the switching control processing when switching from the program of the key station to the program of the local station has been described, but conversely, when switching from the program of the local station to the program of the key station, the same is true. The switching control process may be executed.

In addition, the type and configuration of the digital broadcast transmission system, the control procedure and contents of the switching control device when replacing a program, the type of TS to be handled and its contents,
The types and contents of the freeze image data can be modified in various ways without departing from the scope of the invention.

[0046]

As described above in detail, according to the present invention,
It is possible to provide a digital broadcast signal switching processing device and a digital broadcast signal switching processing method capable of smoothly switching a system of a digital broadcasting signal in real time while making visual fluttering of a frozen image inconspicuous.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a digital broadcast signal transmission system according to an embodiment of the present invention.

FIG. 2 is a timing chart for explaining a processing operation in the system configuration of the above embodiment.

FIG. 3 is a flowchart showing a control procedure of the switching control device shown in FIG. 1 and its contents.

[Explanation of symbols]

11 ... TS separation device, 12 ... TS multiplexer, 13 ... Local material generator, 14 ... Encoder, 15, 16 ... Freeze image data generator, 17 ... TS switching device, 18 ... Switching control device.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5C023 AA21 AA27 BA16 CA01                 5C059 KK39 MA00 MA03 MA05 MA14                       PP05 PP06 PP07 RB10 RC09                       SS02 TA00 TB04 TC13 TC19                       TC41 TC42 TD12 UA02                 5C063 AB03 AB07 AC01 CA11 CA23                       DA02 DA13 DB09

Claims (4)

[Claims] 1. A digital broadcast signal transmission system for multiplexing a plurality of systems of digital broadcast signals obtained by compression-encoding a video signal having a frame structure consisting of two fields and transmitting the multiplexed signals as a transmission signal of a predetermined code amount. A digital broadcast signal switching processing device for inputting two systems of digital broadcast signals to be switched, selectively deriving one of the digital broadcast signals according to the switch signal, and multiplexing the one with the output signal, in each frame of the digital broadcast signal. First image data generating means for generating a frame prediction image data sequence which is continuous with the last data and is required to stop the motion of the image in the frame; and the last data in each frame of the digital broadcast signal. Generates a series of field-predicted image data needed to freeze the motion of the image in a continuous frame. The second to
Image data generating means, the two-system digital broadcast signals, and the first and second digital broadcast signals.
Switching means for selectively deriving at least one of the outputs of the image data generating means as a signal to be multiplexed with the transmission signal, and monitoring the code amount of the transmission signal when the switching signal is input. After comparing the code amount with the predetermined code amount and switching the switching means from the switching source system to one of the outputs of the first and second image data generating means in accordance with the comparison result, A digital broadcast signal switching processing device comprising: a switching control unit that switches the switching unit to a switching destination system. 2. The switching control means fetches and compares the code amount of the output of the switching means and the code amount of the digital broadcast signal as the switching destination, and from the comparison result, the digital broadcast signal as the switching source is determined. 2. The digital broadcast signal switching processing device according to claim 1, wherein the switching means is controlled so that the code amount and the code amount of the digital broadcast signal of the switching destination are continuous. 3. The first image data generating means includes an intra-coded screen in which each of the two systems of digital broadcast signals is one frame, a first prediction screen created based on this screen, and A screen group structure (GOP: Group of Pictures) having a second prediction screen created based on the first prediction screen
2. When the first prediction screen of frame prediction is generated, the second image data generating means generates data of the first prediction screen of field prediction. The described digital broadcast signal switching processing device. 4. The present invention is applied to a digital broadcast signal transmission system that multiplexes digital broadcast signals of a plurality of systems in which a video signal having a frame structure consisting of two fields is compression-encoded and sends out as a transmission signal of a predetermined code amount. A digital broadcast signal switching processing method of inputting two digital broadcast signals to be switched, selectively deriving one of the digital broadcast signals according to the switching signal, and multiplexing the one with the transmission signal, And a first image data generator for generating a frame prediction image data sequence that is continuous with the last data in each frame of the digital broadcast signal and is necessary for stopping the motion of the image in the frame, and the digital broadcast signal. The data that is continuous with the last data in each frame of The generated image data column of de predicted 2
And a first step of monitoring the code amount of the transmission signal and comparing the code amount with the predetermined code amount when the switching signal is input, In accordance with the comparison result in the first process, one of the outputs of the first and second image data generators is switched and output from the digital broadcast signal of the switching source system to be multiplexed with the transmission signal, Then, a second step of switching and outputting the digital broadcast signal of the system to be switched and multiplexing it with the transmission signal is carried out.