KR100544172B1 - Videophone with a function of encoding still picture - Google Patents

Abstract

A video telephone suitable for implementing a surveillance system by having a still image compression encoding function.

The video encoding / decoding unit of the video telephone according to the present invention converts an NTSC / PAL signal input through a camera into a CIF (Common Intermediate Format), which is a standard input image of H.261, or performs the reverse operation to provide the monitor to the reverse. NTSC / PAL <-> CIF interconverter; A video codec unit encoding the CIF / QCIF image provided by the NTSC / PAL <-> CIF interconverter through an encoding scheme such as H.261, H.263, or vice versa; And a still image encoder for still image encoding the CIF image provided by the NTSC / PAL <-> CIF interconversion apparatus through a coding scheme such as JPEG.

The video telephone according to the present invention has an effect that a clear screen can be transmitted by adding a still image encoder to the image encoder / decoder.

Video phone, still picture, H04M

Description

Videophone with a function of encoding still picture}

1 is a block diagram showing the configuration of a conventional video telephone.

FIG. 2 is a block diagram illustrating a detailed configuration of an image encoding / decoding unit illustrated in FIG. 1.

3 is a block diagram showing a detailed configuration of a video encoding / decoding unit having a function of encoding still images in a video telephone according to the present invention.

The present invention relates to a video telephone, and more particularly, to a video telephone suitable for implementing a surveillance system by having a still image compression encoding function.

A video phone is a device that provides a voice call function and a video call function to a phone supporting a communication network such as PSTN, ISDN, LAN, and the like, while talking to each other while looking at the other party's location.

Surveillance system is a system that informs the central station of an emergency situation caused by external intrusion or the like by using a surveillance camera or various sensors. Considering that the camera used in the surveillance system is also incorporated in the video telephone, methods have been devised to use the video telephone as a terminal of the surveillance system.

However, since the conventional video telephone uses H.261, H.263, etc., which are low compression rate image compression methods, there is a problem that the transmitted image is not clear, and thus it is not widely used in a surveillance system.

It is an object of the present invention to provide an improved video telephone capable of transmitting images of clear picture quality, which is devised to solve the above problems.

The video telephone according to the present invention achieves the above object is a video encoding / decoding unit for encoding the image input through the camera or to decode the received video signal to provide to the monitor, the audio input or received via the microphone The image encoding is performed by multiplexing the results encoded by the speech encoding / decoding unit, the image encoding / decoding unit, and the speech encoding / decoding unit by decoding an audio signal and demultiplexing the image signal and the audio signal from the received signal. A multiplexer / demultiplexer unit for providing a decoding unit and a speech encoding / decoding unit, and a network connection unit for transmitting the result multiplexed in the multiplexer / demultiplexer unit to the outside or providing a signal received from the outside to the multiplexer / demultiplexer unit In the video telephone, the zero The encoding / decoding unit converts an NTSC / PAL signal input through the camera into a Common Intermediate Format (CIF), which is a standard input image of H.261, or performs the reverse operation, thereby providing the NTSC / PAL <-> to the monitor. CIF interconverter; A video codec unit encoding the CIF / QCIF image provided by the NTSC / PAL <-> CIF interconverter through an encoding scheme such as H.261, H.263, or vice versa; And a still image encoder for still image encoding the CIF image provided by the NTSC / PAL <-> CIF interconversion apparatus through a coding scheme such as JPEG. Hereinafter, the configuration and operation of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram showing the configuration of a conventional video telephone. The apparatus illustrated in FIG. 1 encodes an image input through a camera 10 through an image encoder / decoder 12, and encodes a voice input through a microphone 14 through a voice encoder / decoder 16. Encode The results encoded by the image encoding / decoding unit 12 and the speech encoding / decoding unit 16 are multiplexed by the multiplexer / demultiplexer unit 18, and are publicly switched telephone network (PSTN) and ISDN (through the network connection unit 20). It is transmitted through Integrated Services Digital Network (LAN), Local Area Network (LAN), etc.

On the other hand, the video / audio multiplexed signal input from the outside is separated into a video signal and an audio signal in the multiplexer / demultiplexer unit 18. The separated video signal is restored by the video encoding / decoding unit 12 and displayed on the monitor 22. On the other hand, the separated speech signal is recovered through the speech encoding / decoding section 16 and output through the speaker 24.

The data port 26 inputs image data input by fax, telewriting, etc., and provides the data to the multiplexer / demultiplexer 18 or vice versa.

The system control unit 28 controls the multiplexer / demultiplexer 18 and the network connection unit 20.

FIG. 2 is a block diagram illustrating a detailed configuration of an image encoding / decoding unit illustrated in FIG. 1. The apparatus shown in FIG. 2 includes an A / D converter 30, an NTSC / PAL <-> CIF interconverter 32, a prefilter 34, an image encoding / decoding unit 36, a multiple encoding / decoding unit ( 38) and transmit / receive buffers 40 and 42. The encoding operation of the apparatus shown in FIG. 2 is as follows.

The preprocessor 30

The image input from the camera 10 is digitized through the A / D converter 30, and the CIF (Common Intermediate Format), which is a standard input image of H.261, through the NTSC / PAL <-> CIF interconverter 32. Or QCIF (Quarter CIF), and noise is removed through the prefilter 34.

The image encoding / decoding unit 36 compresses the CIF image by minimizing temporal redundancy and spatial redundancy with an encoding algorithm. The image coding algorithm is a hybrid method that is a combination of motion compensation inter-frame prediction (MC) and discrete cosine transform (DCT).

The multiple encoding / decoding unit 38 uses the statistical properties of the image encoding output (additional information such as main information, motion vector information, and frame information output from the quantizer) output from the image encoding / decoding unit 32. Further compression is performed by Variable Run Length Coder (VLC) and then multiplexed into one bit string according to a predetermined data structure.

In the video call / video conferencing method of p × 64 KBits / s, the transmission rate of the bit stream that combines video, audio, and data must be kept constant according to the p value. Therefore, the preprocessor 30 adjusts the number of frames and the image encoder / decoder 32 adjusts the size of the quantization step in order to keep the amount of information fluctuating according to the degree of motion of the input image signal.

Most security systems in use today require the user to open the door and enter the password to unlock the security system within a limited time. This security system is mainly connected to the door and window detectors, and sends information to the central processing unit if the user does not release the security device within the time limit after detection. In addition, a system using a camera records and stores images at regular intervals or continuously.

Surveillance systems using video phones, which have recently been popularized, do not send alarms, but have built-in answering machines so that users can remotely make calls to places where video calls are installed and use the screen and voice to identify the situation on the site. .

Surveillance system using such a videophone uses the basic functions of the videophone, but since the videophone transmits 5-15 screens per second using H.261, H.263, etc., which is a low transmission rate compression standard, it can transmit a clear screen. There is a problem that can not be.

In order to solve this problem, the video telephone of the present invention is characterized in that a still image can be transmitted by adding a function of encoding a still image. That is, a still image encoder for encoding a still image may be added to the image encoding / decoding unit illustrated in FIG. 2, and one frame may be transmitted as a still image for every few frames. Since the surveillance system receives still images, it is possible to obtain a clearer image of the scene than a compressed video.

3 is a block diagram showing a detailed configuration of a video encoding / decoding unit having a function of encoding still images in a video telephone according to the present invention.

3, the apparatus shown in FIG. 3 further includes a video scaler 44 and a still image encoder 46. Therefore, the same reference numerals are given to the same members as the apparatus shown in FIG. 2, and some of the members will be omitted.

The NTSC / PAL <-> CIF interconverter 36 converts the NTSC / PAL signal input through the camera 10 into Common Intermediate Format (CIF) or QCIF (Quarter CIF), which is a standard input image of H.261. Alternatively, the reverse operation is provided to the monitor 22.

The image encoding / decoding unit 36 compresses the CIF image or vice versa by minimizing temporal redundancy and spatial redundancy with an encoding algorithm.

The multiple encoding / decoding unit 38 compresses the image encoding output from the image encoding / decoding unit 32 by Variable Run Length Coder (VLC) using statistical properties, and according to a predetermined data structure. Multiplex to one bit string or perform the reverse operation.

The image encoding / decoding unit 36 and the multiple encoding / decoding unit 38 collectively constitute the inverse image codec unit 48.

The video scaler 44 converts an image input through the camera 10 into a still image having a predetermined size. In detail, one frame is sampled every several frames to obtain a still image. In addition, the output still image has a fixed aspect ratio and the number of pixels. As is well known, the number of pixels can be adjusted by adjusting the sampling clock.

The still image encoder 46 encodes a still image provided by the video scaler 44 by a still image encoding method such as JPEG.

Since compression methods such as H.231 and H.236 are lossy coding, reconstructed images are clearly visible, and it is difficult to store only one screen because it is a method of sending a difference from previous images.

Since still image compression is basically a lossless encoding method, a reconstructed image is clear, and a previous image is not related to the current image, and thus it can be stored one by one if necessary. In addition, wherever a PSTN, ISDN, LAN, or mobile phone capable of video communication can be used, a surveillance system can be provided regardless of distance.

The compression-encoded result in the still picture encoder 46 is provided to the multiplexer / demultiplexer 18 shown in FIG. The system controller 28 of FIG. 1 controls whether a still image is transmitted through the still image encoder 46 and the multiplexer / demultiplexer 18.

Here, the system control unit as shown in FIG. 1 makes it possible to transmit a clearer image by adjusting the resolution in the still image encoder 46.

When the size of the image input to the still image encoder 46 is the same as the CIF output from the NTSC / PAL <-> CIF interconverter 42, the video scaler 44 may be omitted.

In this case, the still picture encoder 46 may be designed to encode the CIF picture output from the NTSC / PAL <-> CIF interconverter 40.

As described above, the video telephone according to the present invention has an effect that a clear screen can be transmitted by adding a still image encoder to the image encoding / decoding unit.

Therefore, the surveillance system using this has the advantage of transmitting a clear field screen.

Claims (3)

An image encoding / decoding unit for encoding an image input through a camera or decoding a received video signal and providing the same to a monitor, and an audio encoding / decoding for encoding a voice input through a microphone or decoding a received audio signal and providing the same to a speaker. And a multiplexer which multiplexes the results encoded by the image encoding / decoding unit and the speech encoding / decoding unit, or demultiplexes the image signal and the audio signal from the received signal and provides the image encoding / decoding unit and the speech encoding / decoding unit. A video telephone having a network connection unit for transmitting a result multiplexed in the multiplexer / demultiplexer unit to the outside or providing a signal received from the outside to the multiplexer / demultiplexer unit, wherein the video encoding / decoding unit is provided. NTSC / PAL <-> CIF interconverter which converts NTSC / PAL signal input through the camera into CIF (Common Intermediate Format) which is a standard input image of H.261 or vice versa and provides it to the monitor ; A video codec unit encoding the CIF / QCIF image provided by the NTSC / PAL <-> CIF interconverter through an encoding scheme such as H.261, H.263, or vice versa; And And a still image encoding unit for still image encoding a CIF image provided by the NTSC / PAL <-> CIF interconverter using a coding scheme such as JPEG. The image encoding / decoding unit of claim 1, wherein the image encoding / decoding unit And a video scaler for converting an image input through the camera into a still image having a predetermined size. And the still picture codec unit encodes a still picture provided by the video scaler. The video telephone according to claim 2, wherein the video scaler samples one frame every several frames from the video signal provided from the camera.

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