JP2000041185A - Television signal coding device and decoding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily reproduce an original image before a caption is superimposed at the receiving side and to record the original image via a VTR by extracting a part corresponding to a caption image area from the original image to generate a partial image, coding the partial image to generate a partial image code and multiplexing a main image code and the partial image code to generate the transmitting data. SOLUTION: A caption image signal 152 and an original image signal 153 are inputted to a caption synthesizing part 102, and a main image signal 155 is produced and coded at a main image coding part 103. The coded signal 155 is sent to a code multiplexing part 108 as a main image code 156. The signal 153 is also inputted to a rectangular area extracting part 104 where a partial image is extracted. A partial image signal 157 showing a partial image is coded at a partial image coding part 105 like at the part 103, and a partial image code 158 is sent to the part 108. Then the multiplexed transmitting data 159 are generated at the part 108.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television signal encoder and decoder for superimposing and providing character information such as advertisements and warnings in digital television broadcasting.

[0002]

2. Description of the Related Art In television broadcasting, text information such as extraordinary news is broadcast by superimposing a subtitle image on a broadcasting station side with respect to an original image as an original program, and superimposing on a receiving side. The displayed image is displayed on the screen as it is. For this reason, when the receiver records the broadcast content on a VTR (video tape recorder) or the like by timer reservation, even subtitle information about extraordinary news, etc., which is almost unnecessary at the time of playing the recorded image, is not included. At the same time, it was recorded on the VTR. Even now, in analog television broadcasting, there is a method by which a receiver can selectively display character information by means such as text multiplex broadcasting using a vertical blanking period. Japanese Patent Application Laid-Open No. 6-237423 proposes a method in which information such as extra news can be selectively displayed by a viewer using this method.

[0003]

According to this method, information such as extraordinary news is transmitted as data such as character multiplexed information in a manner superimposed on a vertical blanking period, and the superimposed information is restored on a receiving side as necessary. Then, they are superimposed on the original image. But,
If it is difficult to satisfy the condition that all decoding devices have this function, and therefore the broadcasting station determines that it is necessary to inform all receivers of the information, the broadcasting station naturally A method of superimposing subtitles such as extra news on the original image is selected in advance. Therefore, in the above case, the original image before the subtitle is superimposed on the receiving side is reproduced, and the
It is difficult to be able to record on a computer.

[0004] Therefore, the present invention provides a digital television broadcasting system for transmitting an image in which subtitles such as extra news are superimposed, while maintaining compatibility with a normal decoding device, while maintaining compatibility with a normal decoding device. An object of the present invention is to provide an encoding device and a decoding device for obtaining an original image before superimposing subtitles in a decoding device in accordance with a selection and recording only the original image on a VTR or the like. I do.

[0005]

To achieve the above object, the present invention relates to an apparatus for encoding a television signal, and more particularly to a subtitle combining apparatus for superimposing a subtitle image on an original image to generate a main image. Means for extracting a portion corresponding to a subtitle image region from an original image to generate a partial image, main image encoding means for encoding a main image to generate a main image code, and partial image And a code multiplexing means for multiplexing the main image code and the partial image code to generate transmission data.

According to a second aspect of the present invention, in the television signal encoding apparatus according to the first aspect, the starting coordinates of the partial image on the screen are the starting coordinates of the effective encoding area of the main image in the main image encoding means. , And the size of the partial image is also specified in units of eight pixels.

A third aspect of the present invention relates to a television signal decoding apparatus, which extracts only a subtitle image insertion area from a main image code obtained by superimposing and encoding a subtitle image on an original image and an original image. Code classifying means for classifying a main image code and a partial image code from received data including an encoded partial image code, and main image code decoding means for decoding a main image code obtained by the classification to generate a main image A partial image code decoding means for decoding the partial image code obtained by the classification to generate a partial image, and reproducing the original image by superimposing the decoded partial image on the decoded main image and outputting the image And superimposing means for outputting a signal.

According to a fourth aspect of the present invention, in the television signal decoding apparatus according to the third aspect, the main image code decoding means, the partial image code decoding means, and the superimposing means are a single image decoding means. The image decoding means is characterized in that the decoding of the main image code and the decoding of the partial image code classified by the code classification means are processed in a time-division manner.

In digital broadcasting using transmission lines such as satellites, terrestrial waves, and cables, a single commissioned broadcaster can easily broadcast on multiple channels. Therefore, as a means for solving the above-described problem, an image before the subtitle is superimposed, that is, data obtained by compression-encoding the original image is generated, and the main image after the subtitle superimposition is multiplexed with the data obtained by compression-encoding. Shall be transmitted.
Thus, when the receiving side selects the original image from the transmitted data, an image without captions can be obtained.

However, in order to compress and encode the entire area of the original image as it is and transmit it, almost the same amount of information as that of the main image is required. Simultaneous transmission leads to a significant decrease in the transmission quality of both. For this reason, of the original image, only the area where the caption is to be superimposed is encoded as a partial image, multiplexed with the code data of the main image, and transmitted. On the receiving side, it becomes possible to obtain the original image by decoding the main image and superimposing the decoded partial image thereon.

According to the present invention, since the partial image has a smaller amount of information than the entire area of the original image, the partial image is transmitted in a limited band, so that the quality of the main image can be reduced compared with the case where only the main image is transmitted. Can be compression-encoded and transmitted without much impairment. On the receiving side, a main image and a partial image are combined to generate an original image, which can be used for recording on a VTR.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an encoding apparatus 1 on the transmission side.
This figure shows a state in which 0 and the decoding device 30 on the receiving side are connected via the transmission line 20. The encoding device 10 receives the partial image synthesis control signal 151, the subtitle image signal 152, the original image signal 153, and the partial image coordinate signal 154 and performs predetermined signal processing to generate transmission data 159.
The transmission data 159 is transmitted from the transmission side to the reception side via the transmission path 20, and is received as the reception data 351 by the decoding device 30.
Is input to The decoding device 30 performs predetermined signal processing on the received data 351 to generate a desired image output signal 358.

FIG. 2 shows the internal configuration of the encoding apparatus 10. The internal configuration and operation will be described below with reference to FIG. When broadcasting extraordinary news, inserting advertisements, inserting a logo or the like that means copy guard, or issuing a warning in the event of a disaster, the transmitting side activates the partial image synthesis control signal 151 to activate the code. Device 1
The switch 101 is closed within 0. As a result, the caption image signal 152 and the original image signal 153 are input to the caption synthesizing unit 102, and the subtitle image 5
A main image signal 155 representing a main image 503 obtained by synthesizing 02 is generated. The main image signal 155 is encoded by the main image encoding unit 103 configured as a compression encoding device such as MPEG, and is transmitted to the code multiplexing unit 108 as a main image code 156 from here. The original image signal 153 is also input to the rectangular area extraction unit 104, where a rectangular area wider than the combined subtitle image is extracted as the partial image 504. The partial image 504 to be extracted is specified by the partial image coordinates related to the partial image coordinate signal 154. In order to make the boundaries of the combined image less noticeable, the partial image 504
Start coordinates of the effective coding area of the main image in the main image coding unit 103 are determined by the DCT used in MPEG.
It is specified by the number of pixels which is a multiple of the square area of 8 × 8 pixels which is the minimum unit of (discrete cosine transform). Partial image 5
Similarly, the size of 04 is designated by the number of pixels which is a multiple of the square area of 8 × 8 pixels. The partial image signal 157 representing the partial image 504 is output by the partial image encoding unit 105
Like the main image encoding unit 103, the image is encoded using a compression encoding method such as MPEG. The partial image code 158 obtained by the encoding is a partial image synthesis control signal 151.
Switch 1 closed by activating
06 to the code multiplexing unit 108. Further, the partial image coordinates 154 are also transmitted to the code multiplexing unit 108 via the switch 107 closed by the partial image synthesis control signal 151.
Is input to The code multiplexing unit 108 generates multiplexed transmission data 159 based on the input partial image synthesis control signal 151, main image code 156, partial image code 158, and partial image coordinate signal 154. Actually, information such as an audio signal and data (not shown) is also multiplexed by the code multiplexing unit 108.

FIG. 3 shows the internal configuration of the transmission line 20. The transmission path 20 includes a modulation device 201 at a transmission end and a demodulation device 202 at a reception end. The transmission data 159 generated by the encoding device 10 is modulated by the modulation device 201, and transmitted from the modulation device 201 directly to the receiving side via the transmission line 203 or in the form of a terrestrial wave 251 or a satellite wave 252. , Demodulated here, and received data 35
1 is sent to the decoding device 30. In the case of transmission by the terrestrial wave 251, transmission data 159 modulated by the modulation device 201 is emitted as a radio wave from the transmission antenna 204, received by the reception antenna 205, and received by the demodulation device 202.
Is input to In the case of transmission by satellite wave 252,
Transmission data 159 modulated by modulation apparatus 201 is emitted as radio waves from transmission antenna 206, received by reception antenna 207, and input to demodulation apparatus 202.

FIG. 4 shows the internal configuration of the decoding device 30. Hereinafter, the internal configuration and operation of the decoding device 30 will be described with reference to FIG. The decoding device 30 includes a code classification unit 301 at an input end thereof. Here, a main image code 352 corresponding to the main image code 156 and a partial image code 3 corresponding to the partial image code 158 are obtained from the received data 351.
53, a partial image coordinate 354 corresponding to the partial image coordinate signal 154 and a partial image synthesis control signal 355 corresponding to the partial image synthesis control signal 151 are separated. Main image code 3
52, partial image code 353 and partial image coordinates 354
Is input to an image restoration unit 40 provided in the decoding device 30, where the image is restored and an image output signal 358 is output. The partial image synthesis control signal 355 is input to the control unit 302, and the output signal is input to the image restoration unit 40 as a control signal. The control unit 302 controls the partial image synthesis control signal 3
When 55 is active, the receiver sends a mode control signal 356 for outputting the original image through the operation of the operation unit 303 to the control unit 302, and inputs an original image selection signal 357 to the image restoration unit 40 via the control unit 302. Let it. The image restoration unit 40 receives the original image selection signal 357,
The main image or the original image in which the caption is superimposed is restored, and an image output signal 358 is output. This image output 358 can be used, for example, for recording a VTR.

The image restoration section 40 will be described in more detail with reference to FIG. The image restoration section 40 includes a partial image code decoding section 402 separately from the main image code decoding section 401. The main image code decoding unit 401 decodes the main image code 352 compressed by a compression method such as MPEG to generate a decoded main image 450. On the other hand, the partial image code decoding unit 40
2 decodes the partial image code 353 similarly compressed by a compression method such as MPEG, and specifies the position of the partial image by the partial image coordinates 354. The obtained decoded partial image 451 is sent to the superimposing unit 404 via the switch 403 when the original image is selected by the original image selection signal 357. Superimpose section 404 decodes main image 4
The original image 505 (= 501) is restored by superimposing the decoded partial image 451 on 50, and an image output signal 358 is output.

Then, this image output signal 358 is
Thus, an original image without captions can be recorded. At the same time, the main image code decoding unit 401
By outputting the decoded main image 450 output from the TV screen (display device) to a TV screen (display device), it is possible to see an image including subtitles such as extra news when watching in real time. In the case of a normal decoding device, only the main image code is decoded and output. Therefore, when viewed on a display device, the same image as that of the conventional device is viewed, and the transmission data is compatible with the conventional device. The nature is also maintained.

FIG. 7 shows another example of the configuration of the image restoring section 40. The operation thereof will be described below with reference to FIG. In the image restoration unit 40a, the two decoding units, the main image decoding unit and the partial image decoding unit, are not physically separated. Here, a single image decoding unit 405 is provided, and decoding of each image is performed in a time-division manner. To process. This time division processing is realized by a software technique. Therefore, the image restoration unit 40a includes a single image decoding unit 405 and a memory 406 that temporarily stores a restored image.

In the image restoration section 40a shown in FIG.
First, the main image code 352 is taken into the image decoding unit 405, and the main image (see FIG. 5: main image 503) is decoded (FIG. 8: step 801). The decoded main image is written to the memory 406 (Step 802). next,
The state of the original image selection signal 357 is checked (step 80).
3) If the restoration of the original image is selected, the process proceeds to the next processing step 804. When the restoration of the main image is selected, the process returns to the first step 801 to adjust the timing with a video synchronization signal (not shown) and shift to the processing of the next main image. In step 804, the partial image code 353 is added to the data.
Is checked, and if so, they are decoded (step 805), and the decoded partial image 5
04 is overwritten in the memory 406 in accordance with the partial image coordinate signal 354. These operations are performed in one field or one
It is repeatedly executed in synchronization with a video synchronization signal such as a frame.

The partial image data written in the memory 406 is read out in synchronization with a video synchronization signal (not shown) to generate an image output signal 358.

[0021]

According to the present invention, in a limited transmission band,
From the received data transmitted to the receiving side in the form of the main image obtained by superimposing subtitles on the original image on the transmitting side with minimal degradation of image quality, before superimposing on the receiving side The original image can be restored, and unnecessary subtitles can be deleted during the recording process of the receiver, and only the desired original image can be recorded.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing a state in which an encoding device and a decoding device according to the present invention are connected via a transmission line.

FIG. 2 is a block diagram showing an internal configuration of the encoding device in FIG. 1;

FIG. 3 is a block diagram showing an internal configuration of a transmission line in FIG. 1;

FIG. 4 is a block diagram showing an internal configuration of the decoding device in FIG. 1;

FIG. 5 is an explanatory diagram illustrating an image processing process of the encoding device in FIG. 2 with reference to an image example.

FIG. 6 is an explanatory diagram illustrating an image processing process of the decoding device in FIG. 4 with reference to an image example in FIG. 5;

FIG. 7 is a block diagram showing another embodiment of the image restoration unit shown in FIG. 4;

FIG. 8 is a flowchart for explaining the operation of the image restoration unit in FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Encoding apparatus 102 Subtitle synthesizing part 103 Main image encoding part 104 Rectangular area extraction part 105 Partial image encoding part 108 Code multiplexing part 151 Partial image synthesis control signal 152 Subtitle image signal 153 Original image signal 154 Partial image coordinate signal 159 Transmission data 20 Transmission line 201 Modulation device 202 Demodulation device 30 Decoding device 301 Code classification unit 351 Received data 357 Original image selection signal 358 Image output signal 40 Image restoration unit 40a Image restoration unit 401 Main image code decoding unit 402 Partial image code decoding Unit 404 superimpose unit 405 image decoding unit 406 memory

Continued on the front page F term (reference) 5C023 AA06 AA11 AA18 AA21 AA26 AA27 AA28 BA01 BA11 BA15 BA16 CA01 CA05 CA08 DA08 EA02 EA03 5C025 AA25 AA28 BA28 CA01 CA09 CB07 DA05 5C063 AB03 AC01 AC10 CA09 CA10

Claims (4)

[Claims] 1. A subtitle synthesizing means for generating a main image by superimposing a subtitle image on an original image, and an area extracting means for extracting a portion corresponding to the subtitle image area from the original image to generate a partial image Main image coding means for coding the main image to generate a main image code; partial image coding means for coding the partial image to generate a partial image code; and the main image code and the partial image code And a code multiplexing means for generating transmission data by multiplexing the signals. 2. The television signal encoding apparatus according to claim 1, wherein the starting coordinates of the partial image on the screen are set to 8 based on the starting coordinates of the effective encoding area of the main image in the main image encoding means. An encoding apparatus for a television signal, which is specified in units of pixels, and the size of the partial image is also specified in units of 8 pixels. 3. A main image code obtained by superimposing and encoding a subtitle image in an original image, and a main image code including a partial image code obtained by extracting and encoding only a subtitle image insertion area from an original image. Code classification means for classifying an image code and a partial image code, main image code decoding means for decoding a main image code obtained by the classification to generate a main image, and decoding a partial image code obtained by the classification. Television comprising partial image code decoding means for generating a partial image, and superimposing means for superimposing a decoded partial image on a decoded main image to reproduce an original image and output an image output signal Signal decoding device. 4. The television signal decoding apparatus according to claim 3, wherein said main image code decoding means, partial image code decoding means, and superimposing means are constituted by a single image decoding means. An image decoding device is a television signal decoding device for processing the decoding of the main image code and the decoding of the partial image code separated by the code separation device in a time-division manner.