KR100615384B1 - Method and apparatus for reducing dependency between record frame rate and transmission frame rate - Google Patents

Abstract

The present invention relates to a digital video recorder (DVR), and more particularly, to a method and apparatus for alleviating the dependency of a network transmission frame rate according to a recording frame rate in an MPEG compression DVR system.

According to the present invention, by compressing an image other than a frame to be recorded to another channel and compressing it for a network before compressing the image, the recording image and the network transmission image can be compressed in a separate channel. It can take full advantage of the feature and ease the FPS dependency between video for recording and video for network delivery.

DVR, frame, recording, transmission

Description

METHOD AND APPARATUS FOR REDUCING DEPENDENCY BETWEEN RECORD FRAME RATE AND TRANSMISSION FRAME RATE}

1 is a schematic diagram of a DVR system according to the prior art.

2 is a flowchart of an image processing process in a DVR system according to the prior art.

3 is a schematic diagram of a DVR system according to an embodiment of the present invention.

4 is a flowchart of an image processing process in a DVR system according to an embodiment of the present invention.

5 is a schematic diagram of a DVR system according to another embodiment of the present invention.

6 is a flowchart of an image processing process in a DVR system according to another embodiment of the present invention.

The present invention relates to a digital video recorder (Digital Video Recorder, DVR), and more particularly to a method and apparatus for alleviating the dependency of the network transmission frame rate according to the recording frame rate in the DVR system of MPEG compression method. .

DVR means A / D conversion of analog video signal input to surveillance camera into digital video data, and high resolution digital video storage and transmission device that can record and play for a long time by compressing input video data. It is divided into DVR and home DVR. Especially, home DVR is called PVR (Personal Video Recorder).

The DVR's function is to capture video signals from surveillance cameras on the video capture board, convert them into high quality digital signals on the computer's hard disk, compress and store them, and then record and search the digital images recorded by the user. Monitoring function to monitor and monitor multiple camera images in one monitor, and image transmission function that enables recording search and real-time screen monitoring using telephone line, LAN, leased line and internet even in remote places. It can be divided into functions and the like.

In case of DVR with network function, network transmission capacity may be variable according to network performance or situation. Therefore, it is normally used for recording search and network transmission to transfer video signal input to DVR to network for remote search or remote monitoring. It is possible to determine how many frames per second are used for each video.

In the case of a DVR using a still image compression method (e.g., JPEG), since there is no dependency between front and rear images, no special technique is required to simultaneously support recording and network transmission. For example, at the same time, 20 frames are recorded by capturing 30 frames of compressed video, and only 10 or 15 frames are arbitrarily selected and used for network transmission, and frame selection may be arbitrarily performed.

However, in the case of a DVR using a video compression method (eg, MPEG), the video of the frame is only available if a few before and after video frames are normal due to the characteristics of the Group of Pictures (GOP) structure in which I, P, and B frames are interdependent. Restoration is possible. Therefore, it is impossible to restore an image when only an arbitrary image of the 30 frame image is selected for recording or network transmission.

Due to these characteristics, in the case of MPEG video, compression is generally performed according to the number of recording frames or the number of network transmission frames without compressing all the obtained images. In this case, there is a problem that one video frame needs to be compressed once for recording and once for network transmission, beyond the performance limitation of the MPEG compression chip. Therefore, in most DVRs, the compressed video for recording is used again for network transmission. As a result, the number of frames and the image quality of the network transmission video are completely dependent on the recording video. In other words, if only 15 frames are recorded, only 15 frames of network transmission are possible, and thus the frame rate of recording and network transmission images, that is, frames per second (FPS), are inevitably the same.

This will be described in detail with reference to the accompanying drawings.

1 is a schematic diagram of a DVR system according to the prior art, and FIG. 2 is a flowchart of an image processing process in the DVR system according to the prior art.

Through the four channels of the first surveillance camera 101, the second surveillance camera 102, the third surveillance camera 103, and the fourth surveillance camera 104, images of 30 FPS are respectively multiplexed by the frame mux 110. When applied to (step 210), the multiplexer 110 is multiplexed using a known multiplexing method to give an ID for each channel to be transmitted to 30FPS (step 220).

The transmitted video signal is received by a demultiplexer (ID DEMUX) 120 assigned with an ID for each channel, and the demultiplexer 120 separates the received 30FPS image into four 7.5FPS video signals according to channels (step 230). .

The compression rate may be determined according to the type, importance, usage, etc. of each channel image. For this purpose, a frame selector (131, 132, 133, 134) is performed for each channel between the demultiplexer 120 and the encoder for each channel. Is inserted to determine whether a frame is to be encoded according to a given frame rate (step 240), thereby determining the compression rate.

Subsequently, each video signal is encoded by a corresponding channel encoder, and the video signals of the first to fourth channels from the first to fourth surveillance cameras are respectively the first channel encoder (CH1 ENC) 141 and the second channel. The encoder is encoded by the encoder CH2 ENC 142, the third channel encoder CH3 ENC 143, and the fourth channel encoder CH4 ENC 144 (step 250).

In FIG. 1, the first channel is recorded at 0 FPS, the second channel is 3 FPS, the third channel is 5 FPS, and the fourth channel is recorded at 7.5 FPS. In the case of the first channel, no frame is selected and all are selected. The frame was discarded, the frame selection was performed at 3 FPS for the second channel, the frame selection was performed at 5 FPS for the third channel, and all frames are selected for the fourth channel. As a result, the first to fourth channel encoders 141, 142, 143, and 144 encode only the selected frame for each channel.

If it is determined to store the encoded image (step 260), the storage server 150 receiving the encoded image is stored in the storage device 170, such as a disk (step 265), and then the same image to the network If it is determined to transmit (step 270), the network server 160 having received the encoded image transmits it to the external network 180 through a known network interface (step 275). Therefore, when the storage image is transmitted to the network as it is, the FPS of the image stored in the storage device 170 and the image transmitted to the network 180 are completely the same, and even when only a portion of the storage image is transmitted to the network. Since the FPS of the video for network transmission is smaller than that of the video for storage, the frame rate of the video stream for network transmission is completely dependent on the frame rate of the video stream for storage.

An object of the present invention is to solve the above problems by mitigating the FPS dependency between video for recording and video for network transmission in an MPEG compression DVR.

In addition, an object of the present invention is to provide a DVR apparatus and method capable of efficiently performing image transmission to a network by selecting an image having an appropriate FPS according to the network environment.

In addition, the present invention is to provide a DVR device and method that can easily alleviate the FPS dependency between the video for recording and video for network transmission by changing only the channel ID of the input frame, without changing the existing DVR configuration The purpose.

In addition, the present invention, by compressing the video other than the frame to be recorded to another channel and compressing it for the network before compressing the video, it is possible to compress the video for recording and video for network transmission in a separate channel, It is an object of the present invention to provide a DVR device and a method thereof that can fully utilize the function and can alleviate the dependency of the FPS between video for recording and video for network transmission.

Hereinafter, with reference to the accompanying drawings will be described in detail the present invention.

3 is a schematic diagram of a DVR system according to an embodiment of the present invention, and FIG. 4 is a flowchart of an image processing process of a DVR system according to an embodiment of the present invention.

Through the four channels of the first surveillance camera 301, the second surveillance camera 302, the third surveillance camera 303, and the fourth surveillance camera 304, images of 30 FPS are respectively multiplexed by the frame multiplexer (Frame MUX, 310). In step 410, the multiplexer 310 multiplexes the signals using a known multiplexing method, assigns IDs to respective channels, and transmits the signals to 30FPS (step 420).

The transmitted video signal is received by a demultiplexer (ID DEMUX) 320 assigned with an ID for each channel, and the demultiplexer 320 separates the received 30FPS image into four 7.5FPS video signals according to channels (step 430). .

The compression rate may be determined according to the characteristics of the type of image, the importance, and the use of the channel. For this purpose, a frame selector (New Frame Selector, 331, 332, 333, 334) is performed between the demultiplexer 320 and the encoder for each channel. Inserts and selects the frame to be recorded and the frame to be transmitted to the network. (440 steps)

Subsequently, an encoder for each channel is allocated to each of the separately selected images to encode the video for recording and the video for network transmission. In other words, the video signals of the four channels from the first to fourth surveillance cameras are divided into two channels by the frame selectors 331, 332, 333, and 334 for each channel, and the first to fourth channels for each of the separated channels. Eighth channel encoders (CH 1 to 8 ENC, 341 to 348) are allocated and encoded into a storage image (step 450) or an image for network transmission (step 452).

In FIG. 3, the first channel is recorded at 0 FPS, the second channel is 3 FPS, the third channel is 5 FPS, and the fourth channel is recorded at 7.5 FPS. For the first channel, no frame is selected. All frames are encoded at 7.5 FPS by the fifth channel encoder 345, and frame selection is performed at 3 FPS for the second channel, so the remaining frames are encoded at 4.5 FPS by the sixth channel encoder 346. Since the frame selection was performed at 5 FPS for 3 channels, the remaining frames are encoded at 2.5 FPS by the 7th channel encoder 347, and for the 4th channel, all frames are selected and 7.5 by 4th channel encoder 344. It is encoded in FPS.

In the conventional case, a frame that is not selected for recording is removed through a frame selector. However, in the present invention, all frames are encoded for recording and network transmission.

The network video passed through the fifth, sixth, seventh, and eighth channel encoders 345, 346, 347, and 348, which are network stream encoders for encoding a network transmission image, is transmitted to the server 360 for a network. If it is determined to transmit to the network (step 470), it is transmitted to the external network 380 via the network interface (step 475). Meanwhile, the recorded video passing through the first, second, third, and fourth channel encoders 341, 342, 343, and 344, which are record stream encoders encoding the video for recording, is transmitted to the storage server 370. If it is determined to be stored (step 460), it is stored in the storage device 370 such as a disk (step 465), otherwise it is transmitted to the server 360 for a network.

The video encoded by the recorded video encoder may also be transmitted to the server 360 for a network. In this case, it is determined whether to transmit to the network (step 470) and transmitted to the external network 380 through the network interface (step 475). Or end without further processing (step 480).

According to the above configuration, the video for recording may be supplied through the first, second, third, and fourth channels, while the video for network transmission may be supplied through all of the first to eighth channels. The network server 360 may receive a network transmission image through the network image encoders 345, 346, 347, and 348 or may receive a recording image through the recorded image encoders 341, 342, 343, and 344. 3, the image from the first camera 301 may be selectively transmitted at 0 or 7.5 FPS, the image from the second camera 302 may be selectively transmitted at 3 or 4.5 FPS, and the third The image from the camera 303 may be selectively transmitted at 5 or 2.5 FPS, and the image from the fourth camera 304 may be selectively transmitted at 7.5 or 0 FPS.

In the above embodiment, the frame selection function of the present invention was installed in the encoder chip of the DVR. Alternatively, the frame selection logic may be independently configured between the multiplexer chip and the encoder chip. Such another embodiment will be described with reference to FIGS. 5 and 6.

5 is a schematic diagram of a DVR system according to a second embodiment of the present invention, and FIG. 6 is a flowchart of an image processing procedure of the DVR system according to the second embodiment of the present invention.

Through the four channels of the first surveillance camera 501, the second surveillance camera 502, the third surveillance camera 503, and the fourth surveillance camera 504, images of 30 FPS are respectively multiplexed by the frame multiplexer (Frame MUX, 510). In step 610, the multiplexer 510 multiplexes the signals using a known multiplexing method to assign IDs to each channel and transmit the IDs to the frame selector at 30 FPS (step 620).

The frame selector consists of a demultiplexer (ID DEMUX, 520), a frame select logic (New Frame Selector, 531, 532, 533, 534) and a multiplexer (ID MUX, 522). When the data is transmitted to 520 and separated into four 7.5 FPS images, the frame selection logic 531, 532, 533, and 534 separates and selects the frame to be recorded and the frame to be transmitted to the network (step 630). The IDs are divided by the multiplexer ID MUX 522 for recording and network and transmitted to the encoder chip (step 640).

The encoder chip may be comprised of a conventional demultiplexer 524 with an eight channel ID and conventional eight channel encoders 541-548. The demultiplexer 524 branches the image frames for each channel according to the assigned ID (step 650), and assigns an encoder for each channel for each branched image frame to encode the image for storage (step 660) or to encode the image for network transmission. (Step 662). Even in this case, video frames from the camera are divided for recording and network transmission so that all frames are encoded.

The network video passed through the fifth, sixth, seventh and eighth channel encoders 545, 546, 547, and 548, which are network stream encoders for encoding a network transmission image, is transmitted to the server 560 for the network. If it is determined to transmit to the network (step 680), it is transmitted to the external network 580 via the network interface (step 685). Meanwhile, the recorded video passing through the first, second, third, and fourth channel encoders 541, 542, 543, and 544, which are record stream encoders encoding the video for recording, is transmitted to the storage server 550. If it is determined to be stored (step 670), it is stored in a storage device 570 such as a disk (step 675), otherwise it is transmitted to the server 560 for the network.

Even in the present embodiment, the video encoded by the recorded video encoder may be transmitted to the server 560 for the network. In this case, it is determined whether to transmit to the network (step 680) and transmitted to the external network 580 through the network interface. Or (step 685) or terminate without further processing (step 690).

According to the above configuration, the video for recording may be supplied through the first, second, third, and fourth channels, while the video for network transmission may be supplied through all of the first to eighth channels. The network server 580 may receive a network transmission image through the network image encoders 545, 546, 547, and 548 or may receive a recording image through the recorded image encoders 541, 542, 543, and 544. Therefore, as shown in FIG. 5, the FPS of the image for network transmission may be selected independently of the FPS of the image stored in the storage device 570.

Although the present invention has been described above according to a preferred embodiment of the present invention, the scope of the present invention is not limited to the above embodiments or the accompanying drawings, and is not limited to the scope of the present invention as set forth in the appended claims. Various variations are possible in.

For example, in the above embodiment, a multiplexer, an encoder, or the like, which is a component of the DVR, is described as being implemented as a chip, but each component may be a separate device or a circuit. In addition, the recording server and the network server do not necessarily need to be separate servers, and may also be replaced by a recording process, a network transmission process, or the like without being limited to a physically independent device called a server. In addition to the MPEG, the present invention can be commonly applied to various video compression codecs of a method of recording a difference between images over a certain unit time in order to improve compression efficiency such as H.263 H.264.

According to the present invention, there is provided a DVR apparatus and method that can alleviate the FPS dependency between the video for recording and the video for network transmission in the MPEG compression type DVR.

In addition, according to the present invention, there is provided a DVR device and a method capable of efficiently performing video transmission to the network by selecting an image having an appropriate FPS according to the network environment or the network conditions at the time of transmission.

In addition, according to the present invention, there is provided a DVR apparatus and method that can easily alleviate the FPS dependency between the recording video and the network transmission video by changing only the channel ID of the input frame, without changing the existing DVR configuration do.

In addition, according to the present invention, by compressing a video other than the frame to be recorded to another channel and compressing it for a network before compressing the video, the recording video and the network transmission video can be compressed in separate channels. The present invention provides a DVR apparatus and method for maximizing the function of the chip and mitigating the FPS dependency between video for recording and video for network transmission.

In addition, according to the present invention, it is possible to selectively transmit a video for recording and a video for network transmission in accordance with the network conditions. For example, after compressing 20 frames of 30 frames of video obtained from a surveillance camera for recording, and compressing the remaining 10 frames for network transmission, the system transmits video for recording or network according to the network environment. It can be determined and transmitted.

Claims (10)

A multiplexer for multiplexing video signals from N cameras and assigning IDs to respective channels; A demultiplexer connected to the multiplexer, the demultiplexer receiving the video signal from the multiplexer and separating the video signal for each channel according to the ID; A frame selector connected to the demultiplexer and configured to select a video frame for recording and a video frame for network transmission for an image of each channel from the demultiplexer; An encoder connected to the frame selector and discriminating and encoding a video frame for recording and a video frame for network transmission from the frame selector; A storage server connected to the encoder and receiving the recording video encoded by the encoder and storing the image for recording in a storage device; And It is connected to the encoder, includes a network server for receiving the network transmission video and recording video encoded in the encoder and selectively transmit to the network, The frame selector is one frame selector is allocated to each channel, N frame selector for the N channels, characterized in that the DVR device. The method of claim 1, Two encoders are allocated to each encoder, and N recorded video encoders for encoding video frames for recording and N network video encoders for encoding frames for network transmission are provided for N channels. DVR device. The method according to claim 1 or 2, And said demultiplexer, said frame selector and said encoder comprise a single encoder chip. The method according to claim 1 or 2, The video signal is a DVR device, characterized in that the MPEG signal. A multiplexer for multiplexing video signals from a plurality of cameras and assigning IDs to respective channels; A frame selector connected to the multiplexer for receiving the video signal from the multiplexer, separating the video signal according to the ID, separating the video frame for recording and the video frame for network transmission, and then multiplexing and transmitting the video signal. ; An encoder coupled to the frame selector, for separating and multiplexing the multiplexed video signal from the frame selector into channels for recording and video for network transmission; A storage server connected to the encoder and receiving the recording video encoded by the encoder and storing the image for recording in a storage device; And It is connected to the encoder, includes a network server for receiving the network transmission video and recording video encoded in the encoder and selectively transmit to the network, The frame selector is one frame selection means is allocated to each channel, DVR device characterized in that it comprises N frame selection means for the N channels. The method of claim 5, wherein The frame selector receives the video signal from the multiplexer and separates the video signal for each channel according to the ID, and N frames for selecting the video frame for recording and the video frame for network transmission for the video for each channel from the demultiplexer. A multiplexer for assigning and multiplexing IDs for each image frame channel from the selecting means and the N frame selecting means; Two encoders are allocated to each encoder, and N recorded video encoders for encoding video frames for recording and N network video encoders for encoding frames for network transmission are provided for N channels. DVR device. The method according to claim 5 or 6, The encoder comprises a single encoder chip, the frame selector DVR device, characterized in that consisting of a logic or chip separate from the encoder chip. The method according to claim 5 or 6, The video signal is a DVR device, characterized in that the MPEG signal. delete As a method for mitigating the dependency between a recording frame rate and a transmission frame rate in a DVR system, Dividing video signals from a plurality of cameras for each channel; Selecting a video frame for recording and a video frame for network transmission on the divided images for each channel; Generating a recording image and a network transmission image by distinguishing the recording image frame from the image frame for network transmission; Receiving the recording image and storing the recording image in a storage device; And Receiving the network transmission image and the recording image and transmitting one of them to a network.

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