JP2012156654A - Transmitter and moving image transmission system using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmitter and a moving image transmission system using the same in which the transmission amount of data can be reduced and a transmission band required for transmission can be reduced.SOLUTION: An imaging device 1 for transmitting moving image data obtained by imaging is provided. The imaging device 1 transmits to a display device 2 compressed frame data compressed to a differential picture after the imaging device 1 once transmits compressed frame data compressed to a reference picture, and the transmission time of the compressed frame data compressed to the reference picture is set to be longer than the transmission time of the compressed frame data compressed to the differential picture.

Description

  The present invention relates to a transmission device, and more particularly to a transmission device that transmits a moving image in real time and a moving image transmission system using the same.

  2. Description of the Related Art Conventionally, a video transmission system is known that is applied to an interphone system including a door phone slave unit, an interphone master unit, an interphone submaster unit, and the like. In this conventional example, a video compression process is performed by an interphone master unit that is a video transmission apparatus, and packets including compressed video data are individually transmitted to each interphone sub-master unit that is a video reception apparatus. Here, the video compression processing unit of the interphone master unit compresses the video data by a compression method compliant with the MPEG standard (for example, MPEG-4). The video compression processing unit includes a first compression processing unit and a second compression processing unit. Each of the video compression processing units includes an I frame (I picture) that can be decompressed independently and a P frame that can be decompressed only in pairs with the I frame ( Video data is compressed to P picture. Then, the intercom base unit transmits a predetermined number of P frames inserted between a plurality of I frames arranged at regular time intervals.

JP 2009-55367 A

  However, in the above conventional example, since I pictures having a large data size are periodically transmitted, relatively large data is periodically transmitted. For this reason, the above conventional example has a problem that the transmission amount of necessary data becomes large as a whole. In addition, both the I picture and the P picture must be transmitted in the same cycle. However, since the data size of the I picture is large, a large transmission bandwidth per unit time is necessary when transmitting the I picture. There is a problem that a necessary transmission band becomes large.

  The present invention has been made in view of the above points, and provides a transmission apparatus capable of reducing the amount of data transmission and reducing the transmission band necessary for transmission, and a video transmission system using the transmission apparatus. For the purpose.

  The transmitting apparatus of the present invention transmits moving image data, and after transmitting compressed frame data compressed to a reference picture, transmits compressed frame data compressed to a differential picture and compresses the compressed frame data to the reference picture The transmission time of the compressed frame data is longer than the transmission time of the compressed frame data compressed into the differential picture.

  In this transmitting apparatus, the transmitting apparatus compresses moving picture data by compressing each of a plurality of time-sequential frame data included in the moving picture data obtained by the input section for obtaining moving picture data. And a transmission unit that transmits the compressed frame data compressed by the compression unit in chronological order, and the compression unit transmits first frame data of the plurality of frame data to another Compression that compresses to the reference picture that is independent of frame data and can be expanded independently, and compresses the remaining frame data of the plurality of frame data into the differential picture that is a difference from other frame data The transmission apparatus executes compression, and compresses the transmission time of compressed frame data compressed into the reference picture into the difference picture. It is desirable to be longer than the transmission time of the frame data.

  A moving image transmission system according to the present invention includes any one of the transmission devices and a receiving device that receives moving image data.

  The present invention has the effects of reducing the amount of data transmitted and reducing the transmission band required for transmission.

(A)-(d) is operation | movement explanatory drawing of the intercom system to which embodiment of the transmitter which concerns on this invention, and a moving image transmission system is applied. It is a block diagram of an intercom system same as the above. (A)-(c) is explanatory drawing of the conventional compression method.

  Hereinafter, embodiments of a transmission device and a moving image transmission system according to the present invention will be described based on an example applied to a security intercom system (hereinafter simply referred to as “interphone system”).

  As shown in FIG. 2, the intercom system includes an imaging device 1 installed at the eaves of a house, a display device 2 including a master unit (interphone master unit) installed inside the house (indoor), and an outside house ( It is comprised with the subunit | mobile_unit (interphone subunit | mobile_unit) not shown installed in the outdoors. Note that the imaging device 1 and the slave unit are connected to the display device 2 by a transmission line. Moreover, since a conventionally well-known thing can be employ | adopted for a subunit | mobile_unit, detailed description of a subunit | mobile_unit is abbreviate | omitted.

  The imaging device 1 is a transmission device that transmits moving image data, and includes an input unit 10, a storage unit 11, a compression unit 12, a transmission unit 13, and a processing unit 14 as main components.

  The input unit 10 is an imaging unit having a function of imaging a predetermined imaging region, for example, and includes an imaging device (not shown) made of a solid-state imaging device such as a CCD image sensor or a CMOS image sensor. In addition, the input unit 10 includes a control device (not shown) such as a DSP (Digital Signal Processor) that performs a function as a camera together with the imaging device as a main component. When a CMOS image sensor is used as the image sensor, a one-chip camera in which the image sensor and the control device are integrally configured using system-on-chip (SoC) technology or the like is used as the input unit 10. You can also.

  The control device of the input unit 10 captures the output (charge) of the image sensor at a predetermined frame rate (for example, 30 fps). Then, the control device creates and outputs still image data such as digital data in a predetermined format (for example, YUV format), for example, RAW data, based on the captured output of the image sensor. In this way, still image data representing the image of the imaging region is sequentially output from the control device. Therefore, moving image data representing moving images (moving images) in the imaging region can be obtained by the input unit 10. The moving image data obtained from the input unit 10 is composed of a plurality of still image data in time-series order. In the following description, still-image data in time-series order constituting the moving image data (that is, one frame of the moving image data) Hit data) is called frame data.

  The storage unit 11 is a rewritable storage device (storage device) such as a flash memory, SDRAM, or SRAM, and is mainly used for storage (storage) of moving image data obtained by the input unit 10.

  In order to transmit the moving image data obtained by the input unit 10 to the display device 2, the compression unit 12 is, for example, H.264. The video data is compressed by a compression method compliant with standards such as H.264 and MPEG-4. The compression part 12 consists of microcomputers, for example, and performs the following compression process by executing the program memorize | stored in memory. In addition to the microcomputer, a dedicated ASIC (Application Specific Integrated Circuit), FPGA (Field Programmable Gate Array), DSP, or the like can be used for the compression unit 12. The compression of the moving image data is performed by compressing each of a plurality of time-sequential frame data constituting the moving image data. The compression unit 12 creates compressed frame data by executing the following compression processing on the frame data.

  First, the compression unit 12 performs a compression process that compresses (encodes) the first frame data of a plurality of frame data into a reference picture such as an I picture (intra-frame encoded image). The reference picture is a still image compressed image that is independent of other frame data and can be expanded independently. As a compression method to the reference picture, a conventionally well-known method (for example, a still image compression method for obtaining JPEG, I picture, or the like) can be adopted, and detailed description thereof is omitted here.

  Next, the compression unit 12 performs a compression process of compressing the remaining frame data among the plurality of frame data into a differential picture such as a P picture (forward prediction encoded image). The difference picture is a compressed moving image obtained from a difference from other frame data. Note that a conventionally known method (for example, a moving image compression method for obtaining a P picture) can be employed as a compression method to a differential picture, and thus detailed description thereof is omitted here.

  The transmission unit 13 is a communication unit for transmitting the moving image data (compressed moving image data) compressed by the compression unit 12 to the display device 2, and encodes the compressed moving image data (transmission path encoding) to display the display device 2. Output to. Such a transmission unit 13 transmits the compressed moving image data in real time by transmitting the compressed frame data created by the compression unit 12 in time series.

  For example, the processing unit 14 performs a storage process in which a management identification code (for example, a frame number) is attached to the frame data of the moving image data sequentially output by the input unit 10 and stored in the storage unit 11. Further, the processing unit 14 determines whether or not an object (a person in this embodiment) is captured in a frame based on the frame data of the input unit 10 at a predetermined time interval (that is, a person is within the imaging range of the input unit 10). A detection process for determining whether or not it exists is executed. Such detection processing can be realized, for example, by performing image processing on frame data obtained from the input unit 10, and various methods are conventionally provided, and thus detailed description thereof is omitted. When the processing unit 14 detects an object in the detection process, the processing unit 14 performs a transmission process of transmitting moving image data obtained from the input unit 10 to the display device 2 within a predetermined period including the detection time of the target. In the transmission process, the compression unit 12 starts to compress moving image data, and the transmission unit 13 starts transmission of moving image data. For example, a microcomputer is used as the processing unit 14.

  The display device 2 is a receiving device having a function of receiving and displaying moving image data transmitted from the imaging device 1. Such a display device 2 includes a receiving unit 20, a storage unit 21, an expansion unit 22, a display unit 23, and a processing unit 24 as main components.

  The receiving unit 20 is a communication unit for receiving the moving image data transmitted from the imaging device 1, and sequentially decodes the signal including the compressed moving image data transmitted from the transmitting unit 13 (transmission path decoding). Execute the output process.

  Similar to the storage unit 11, the storage unit 21 is a rewritable storage device such as a flash memory, SDRAM, or SRAM.

  The decompressing unit 22 is for decompressing the compressed moving image data received by the receiving unit 20, and decompresses the compressed moving image data by decompressing each compressed frame data. Note that, similarly to the compression unit 12, the decompression unit 22 can include a microcomputer, an ASIC, an FPGA, a DSP, and the like as main components.

  The display unit 23 includes a display device (not shown) such as a liquid crystal display device (LCD) or a CRT. The display unit 23 displays the moving image data (reproduces the moving image) by displaying the compressed frame data expanded by the expansion unit 22, that is, the frames based on the frame data in time series order.

  For example, the processing unit 24 performs a recording process for recording the compressed moving image data received by the receiving unit 20 in the storage unit 21. In addition, when the receiving unit 20 receives the compressed moving image data, the processing unit 24 executes display processing for displaying the compressed moving image data on the display unit 23. In this display process, the decompression unit 22 starts decompressing the compressed moving image data, and the display unit 23 starts displaying the moving image data. Such a processing unit 24 uses a microcomputer in the same manner as the processing unit 14.

  Hereinafter, the operation of this embodiment will be described. In the following description, an I picture is used as a reference picture, and a P picture is used as a difference picture.

  While the imaging apparatus 1 is activated, the imaging unit 1 always captures a predetermined imaging area with a predetermined frame rate by the input unit 10. The frame data captured by the input unit 10 is sequentially stored in the storage unit 11 by the processing unit 14. The processing unit 14 performs the above-described detection process based on the frame data obtained from the input unit 10. As a result of the detection process, when it is determined that the object is captured, the processing unit 14 causes the compression unit 12 to start compressing the moving image data and causes the transmission unit 13 to start transmitting the moving image data.

  Here, the compression unit 12 performs a process of compressing the frame data to be transmitted first into an I picture, and compressing the frame data to be transmitted thereafter into a P picture. Therefore, compressed frame data I1 compressed into an I picture is first transmitted to the display device 2, and then compressed frame data P1 to P7 compressed into a P picture are transmitted to the display device 2 in time series order ( FIG. 1 (a)).

  In the display device 2, the compressed moving image data is received by the receiving unit 20. Then, the compressed moving image data is recorded in the storage unit 21 by the processing unit 24. The processing unit 24 causes the decompression unit 22 to start decompressing the compressed moving image data, and causes the display unit 23 to start displaying the decompressed compressed movie data, that is, the movie data. The decompression unit 22 first decompresses the compressed frame data I1 alone and causes the display unit 23 to display the decompressed frame data A1. The processing unit 24 expands the subsequent compressed frame data P1 to P7 to frame data A2 to A8 with reference to the immediately preceding frame data A1 to A7, and displays the expanded frame data A2 to A8 in time series order. 23 (see FIG. 1B).

  In this way, only the frame data to be transmitted first is compressed into an I picture with a large data size, and the frame data to be transmitted thereafter is compressed into a P picture with a small data size, thereby reducing the amount of data transmission as a whole. be able to. That is, the total data size of the compressed frame data to be transmitted can be made smaller than when frame data is periodically compressed into an I picture and transmitted (see FIGS. 3A to 3C). it can. Further, the frame data to be transmitted first is compressed into an I picture, but the other compressed frame data is converted into a P picture, so that the average value of the data size can be reduced.

  Here, since the compressed frame data transmitted first from the imaging apparatus 1 is compressed into an I picture, the data size is larger than the compressed frame data compressed into a P picture to be transmitted later. In addition, both the compressed frame data compressed into an I picture and the compressed frame data compressed into a P picture must be transmitted in the same cycle. For this reason, when transmitting compressed frame data as in the conventional example, when transmitting compressed frame data that has been compressed into an I picture to be transmitted first, a large transmission band per unit time is required, which is instantaneously required. A large transmission band (see FIG. 1C). Therefore, in the present embodiment, by allowing a delay time from video input to output, the transmission time when transmitting compressed frame data compressed into an I picture is reduced to the compressed frame data compressed into a P picture. The transmission time is longer than the transmission time.

  For example, as shown in FIG. 1 (d), the data size of compressed frame data I1 compressed into an I picture is about twice the data size of compressed frame data P1 to P7 compressed into a P picture. To do. In this case, the transmission time of the compressed frame data I1 compressed into an I picture is set to about twice the transmission time of the compressed frame data P1 to P7 compressed into a P picture. That is, by transmitting one piece of compressed frame data I1 in two steps, the transmission amount per unit time can be reduced. Therefore, it is possible to reduce the transmission band necessary for transmitting the compressed frame data I1 obtained by compressing an image into an I picture.

  As described above, only the frame data to be transmitted first is compressed into an I picture (reference picture), and the other frame data is compressed into a P picture (difference picture). Therefore, the average value of the data size is reduced, and The amount of data transmission can be reduced. In addition, by setting the transmission time when transmitting compressed frame data compressed with an image to an I picture longer than the transmission time when transmitting compressed frame data compressed with an image to a P picture, the transmission band required for transmission is reduced. Can be small. For this reason, it is possible to easily manage the transmission band when performing data communication other than moving image data. Furthermore, since the data size of the compressed frame data to be transmitted is averaged, it is possible to prevent the performance of data communication from being deteriorated due to the transmission timing.

  Note that the configuration of the transmission device and the moving image transmission system of the present embodiment described above is merely an embodiment of the present invention, and is not intended to limit the technical scope of the present invention to the above example, but to the purpose of the present invention. It can be changed to such an extent that does not deviate. For example, in the above example, a P picture is adopted as the differential picture, but a B picture (bidirectional predictive coded image) may be used instead of or together with the P picture.

  In the present embodiment, the processing unit 14 of the imaging device 1 executes a detection process, and when an object is detected by the detection process, transmission of moving image data is started. However, transmission of moving image data may be started when moving image data is obtained from the imaging apparatus 1 regardless of the presence or absence of an object. That is, the timing for starting transmission of moving image data can be appropriately set according to the purpose of use of the moving image transmission system.

  In the present embodiment, the imaging device 1 and the display device 2 constitute the moving image transmission system of the present invention. Here, in the interphone system, since a device with a camera is often used as the slave unit, such a slave unit with a camera and the display device 2 may constitute the moving picture transmission system of the present invention. In this case, the slave unit is a transmission device, and the display device 2 is a reception device.

  In this embodiment, the moving image transmission system of the present invention is applied to an intercom system. However, the moving image transmission system of the present invention can also be applied to a system such as a monitoring system. That is, the moving image transmission system of the present invention is applicable as long as moving image data is transmitted in real time.

1 Imaging device (transmitting device)
DESCRIPTION OF SYMBOLS 10 Input part 12 Compression part 13 Transmission part 2 Display apparatus (reception apparatus)
20 receiving unit 22 decompressing unit 23 display unit I1 I picture (reference picture)
P1 to P7 P picture (difference picture)

Claims (3)

  After transmitting compressed frame data compressed to a reference picture, the compressed frame data compressed to the differential picture is transmitted, and the transmission time of the compressed frame data compressed to the reference picture is transmitted. A transmission apparatus characterized in that the transmission time of compressed frame data compressed into the differential picture is longer.   The transmission device includes: an input unit for obtaining moving image data; and a compression unit that compresses moving image data by compressing each of a plurality of frame data in time series included in the moving image data obtained by the input unit. A transmission unit that transmits the compressed frame data compressed by the compression unit in chronological order, and the compression unit depends on the first frame data among the plurality of frame data with other frame data. Compressing the reference picture that is irrelevant and can be expanded independently, and performing compression processing for compressing the remaining frame data of the plurality of frame data into the differential picture that is a difference from other frame data, The transmitting apparatus transmits a compressed frame data compressed into the differential picture by transmitting a transmission time of the compressed frame data compressed into the reference picture. Transmitting apparatus according to claim 1, wherein the longer than.   A moving image transmission system comprising the transmission device according to claim 1 and a receiving device that receives moving image data.

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