JP3599860B2 - Multi screen creation device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an apparatus that divides a screen into a plurality of parts in a television receiver or the like and creates a multi-screen that displays individual images in each area, and in particular, each individual video signal is image-compressed by MPEG or the like. The present invention relates to a multi-screen creation device suitable for use with digital signals.
[0002]
[Prior art]
In recent years, in digital television broadcasting and the like that are being developed, a plurality of programs are multiplexed on one carrier, and when a certain carrier is demodulated, a multiplexed digital signal in which a plurality of digital video signals are time-division multiplexed can be obtained. .
[0003]
When a user wants to view a certain program from the multiplex digital signal, the digital video signal of the desired program is separated. Usually, since the digital video signal is image-compressed based on the MPEG or the like which is the international standard for image compression, the separated digital video signal is decoded by MPEG or the like, and then the image is displayed.
[0004]
By the way, when performing a so-called multi-screen display in which one screen is divided into a plurality of regions and individual images obtained from the multiplex digital signal are displayed in each region, a plurality of digital video signals are separated from the multiplex digital signal, It is necessary to independently decode MPEG or the like.
[0005]
[Problems to be solved by the invention]
For example, when forming a multi-screen of four regions, four systems of separation circuits and an MPEG decoder are required. Therefore, there has been a problem that configuring a multi-screen multi-screen increases the size of the apparatus and increases the cost.
[0006]
An object of the present invention is to solve the above-mentioned disadvantages, and to provide a multi-screen creation device that is small in size and does not increase the cost.
[0007]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a separating unit that separates one digital video signal from a multiplexed digital signal in which a plurality of compressed digital video signals are multiplexed and transmitted, and the one digital video separated by the separating unit. Detecting means for detecting the start and end portions of the intra-frame encoded from the signal, decoding means for decoding the intra-frame encoded portion detected by the detecting means, and a video signal decoded by the decoding means. Display control means for controlling a display area to be reduced and displayed in one corresponding area on a display screen divided into a plurality of areas corresponding to the plurality of compressed digital video signals; and Control means for outputting a selection command for switching a digital video signal separated by the means to another digital video signal, the control means The intraframe coded terminated portion is detected as soon as by the detecting means, and outputs the selected command to said separating means.
According to a second aspect of the present invention, there is provided a separating means for sequentially separating N (an integer of 2 or more) digital video signals from a multiplexed digital signal in which a plurality of compressed digital video signals are multiplexed and transmitted, and the separating means. Detecting means for detecting an intra-frame encoded start and end portion from the separated N digital video signals, and decoding for sequentially decoding the N intra-frame encoded portions detected by the detecting means; Means, and the N video signals decoded by the decoding means are divided into a plurality of display areas having a display area corresponding to the plurality of compressed digital video signals. Display control means for controlling display in a reduced size in each area, and selection for switching a digital video signal separated by the separation means to another digital video signal Control means for outputting a selection command to the separating means as soon as the detecting means detects the end portion encoded in the frame. .
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, an outline of MPEG will be described prior to the description of embodiments of the present invention.
[0009]
MPEG coding employs motion compensation prediction, DCT (discrete cosine transform), and variable-length coding. As shown in the frame configuration in FIG. 1, an image is I (intra-coded) in a temporal axis prediction mode. ) Pictures, P (predictive-coded) pictures, and B (bi-directly predictive-coded) pictures. The I picture is an intra-frame coded image, the P picture is an inter-frame predicted coded image predicted from a temporally preceding frame, and the B picture is an inter-frame predicted coded image from preceding and succeeding frames.
[0010]
FIG. 2 shows the data hierarchical structure of MPEG. It is constituted as follows from the lower layer. (Block layer)
A block is composed of 8 × 8 pixels adjacent to each other in luminance or chrominance, and DCT is executed in this unit. (Macro block layer)
The macro block is composed of a total of six blocks including four adjacent luminance blocks and two color difference blocks Cb and Cr at the same position on the screen. (Slice layer)
It is composed of a plurality of macro blocks connected in the scanning order of the image. (Picture layer)
It is composed of a plurality of slices and forms one image. The picture is classified into the above-mentioned I picture, P picture, and B picture according to the encoding format. (GOP (Group of Picture) layer)
A GOP is composed of one or more I pictures and zero or more non-I pictures. (Video sequence layer)
A video sequence is composed of one or more GOPs having the same image size, image rate, and the like.
[0011]
Next, the structure of a multiplex digital signal applied to the present invention will be described with reference to FIG.
The multiplexed digital signal has a packet structure called an MPEG transport stream, and a 32-bit packet header for data identification is added to the head of each 88-byte packet. In this packet header, identification data called PID (Packet Identifier) indicating the attribute of the packet is added to 13 bits from the 12th bit to the 24th bit from the top. That is, by looking at this PID, it is possible to know which program the packet belongs to. A plurality of programs are time-division multiplexed on the multiplexed digital signal in packet units.
[0012]
Next, a multi-screen creation device according to the present invention will be described with reference to FIG.
Here, an example will be described in which four programs A to D are multiplexed on one carrier wave, and these four programs are displayed on a 4-split multi-screen.
[0013]
First, the multiplex digital signal input from the input terminal 1 is supplied to the separation circuit 2. The separation circuit 2 separates a digital signal of a desired program based on a program selection command from a control circuit 3 including a microcomputer. The separation circuit 2 separates only the packets of the desired program by referring to the PID of each packet header and supplies the packets to the I picture detection circuit 4 at the next stage. The I picture detection circuit 4 focuses on the start of the picture layer in the MPEG data hierarchy. That is, at the head of each picture layer, a 32-bit start code is followed by a code indicating a picture type in three bits from the end to the eleventh to thirteenth bits. Based on this, an I picture is detected. I do. The detected I picture is supplied to the decoding circuit 5 and MPEG-decoded. The decoded data is supplied to the multi-screen creation circuit 6. The multi-screen creation circuit 6 has a thinning circuit and an image memory for thinning out the pixels of the input I picture to 1/4, and by specifying a predetermined address, the display screen 7 is divided into the respective areas of the divided screen. Can be displayed at any display position.
[0014]
Next, the operation of the above device will be described.
First, the control circuit 3 instructs the separation circuit 2 to select the program A. The separation circuit 2 separates only the packets of the program A by looking at the PID of each packet of the multiplexed digital signal and supplies it to the I picture detection circuit 4. The I picture detection circuit 4 detects the I picture and outputs it to the decoding circuit 5 to execute MPEG decoding. The decoded data for one screen is written to a predetermined area of the image memory with the pixels decimated to 、, and displayed in the upper left display area on the screen of the display device 7.
[0015]
Next, the I picture detection circuit 4 detects the end of the I picture of the program A (the head of the next picture) and transmits an end detection signal to the control circuit 3. When receiving the end detection signal, the control circuit 3 outputs a command to the separation circuit 2 to select the program B.
[0016]
The separating circuit 2 separates only the packet of the program B and outputs it to the I picture detecting circuit 4. Then, the program B image is displayed on the upper right of the display screen by the same processing as described above.
Hereinafter, similarly, the program C and the program D are displayed on the lower left and lower right on the display screen, respectively, and these operations are repeated. As a result, a four-screen multi-screen image is displayed on the display device 7.
[0017]
Here, since the image of each divided area on the display screen is reproduced only from the I picture which is an intra-frame coded image without using a P picture or a B picture which is an inter-frame prediction coded image, the motion is Although it is intermittent, the purpose of displaying a multi-screen is to browse the contents of each program, so that the video in each area does not need to be a complete moving image but a frame-by-frame image. However, if the contents can be understood almost, the initial purpose can be achieved.
[0018]
Since the decoding circuit 5 originally has an image memory for decoding, this memory can also be used as an image memory provided in the multi-screen creation circuit 6. That is, in the normal operation (when the image is not a multi-screen), the decoded image data is written to the entire image memory. However, when a multi-screen is created, the data may be thinned out and written to a partial area. At the time of creating a multi-screen, since only the I picture which is an intra-frame coded image is decoded, there is no need to refer to the contents of the image memory for decoding the next picture, so that there is no hindrance to the decoding operation.
[0019]
Further, the I-picture may be detected by the decoding circuit using the picture type determination function of the decoding circuit, and the detection output may be fed back to the control circuit.
[0020]
【The invention's effect】
As described above, according to the present invention, even when a multi-screen is configured, a plurality of separation circuits and an MPEG decoder are not required, and only one system is required, so that an increase in the apparatus scale and an increase in cost can be suppressed.
[Brief description of the drawings]
FIG. 1 is a diagram showing a frame structure of MPEG.
FIG. 2 is a diagram showing a data hierarchical structure of MPEG.
FIG. 3 is a diagram illustrating a packet structure of a multiplex digital signal.
FIG. 4 is a block diagram of a multi-screen creation device according to the present invention.
[Explanation of symbols]
2 Separation circuit 3 Control circuit 4 I picture detection circuit 5 Decoding circuit 6 Multi-screen creation circuit 7 Display device

Claims (3)

Separating means for separating one digital video signal from a multiplexed digital signal in which a plurality of compressed digital video signals are multiplexed and transmitted;
Detecting means for detecting the start and end portions encoded in the frame from the one digital video signal separated by the separating means,
Decoding means for decoding the part amount corresponding to the intraframe coding is detected by the detection means,
The video signal decoded by the decoding means is reduced and displayed on a corresponding one area on a display screen whose display area is divided into a plurality of areas corresponding to the plurality of compressed digital image signals. Display control means for controlling the
Control means for outputting a selection command to switch the digital video signal separated by the separation means to another digital video signal,
The multi-screen creation device according to claim 1, wherein the control unit outputs the selection command to the separation unit as soon as the detection unit detects the end portion encoded in the frame . Separation means for sequentially separating N (an integer of 2 or more) digital video signals from a multiplexed digital signal in which a plurality of compressed digital video signals are multiplexed and transmitted;
Detecting means for detecting the start and end portions encoded in the frame from the N digital video signals separated by the separating means;
Decoding means for decoding the part amount corresponding to the intra-frame coding of the N detected by the detection means sequentially,
The N video signals decoded by the decoding means are respectively transferred to the corresponding N respective areas on the display screen whose display area is divided into a plurality of areas corresponding to the plurality of compressed digital video signals. Display control means for controlling display to be reduced ,
Control means for outputting a selection command to switch the digital video signal separated by the separation means to another digital video signal,
The multi-screen creation device according to claim 1, wherein the control unit outputs the selection command to the separation unit as soon as the detection unit detects the end portion encoded in the frame . 3. The multi-screen creation device according to claim 1, wherein the digital video signal is compressed according to an MPEG standard.

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