JP4717327B2 - Video input device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a video input device having means for detecting a moving speed of a video input device using a position detection device, an acceleration sensor, or the like of a video input device mounted on a movable object. The present invention relates to an apparatus having means for changing the encoding rate of an input video signal depending on the state of change.
[0002]
[Prior art]
recent years. A large number of image input devices using predictive coding compression means such as MPEG2 and MPEG4 are used as moving picture compression means. In these compressions, there are mainly two types of frame rate control, which are roughly classified into variable bit rate (VBR) and constant bit rate (CBR). VBR is control that averages the amount of encoded data generated, and is generally effective in suppressing changes in image quality.
[0003]
CBR is a means for controlling the generation amount of encoded data to be always constant, and the change in image quality is larger than that of VBR. FIG. 6 shows a general flow of an image encoding frame.
[0004]
Among them, the I frame is called an intra frame and is a base frame. The B frame is a frame that can be predicted from both directions of the preceding and following frames, the P frame is a frame that can be predicted from the previous frame, and data composed of such a group of frames is sent as compressed and encoded data of the image. . Further, the image is reproduced by inversely converting the data. The data of each frame described in the frame flow is data generated upon image input / reproduction.
[0005]
In terms of the use of image input devices, recently, such image compression coding technology is used to fix and use image input devices indoors and outdoors, and portable terminals and other portable types. As an image input device, it has been frequently used outdoors as a video input device that can be freely carried outdoors or mounted on a moving device such as a car.
[0006]
[Problems to be solved by the invention]
In such use, there is a request to send a compression-encoded video frame via a network in real time from a signal input to the image input device.
[0007]
In such a case, with a bit rate such as the VBR described above, an increase in the amount of change in an image to be picked up leads to an increase in compression-coded data depending on the situation of the network through which the transmission delay time on the transmission network increases. May occur, or data loss may occur due to congestion in the network.
[0008]
On the other hand, the CBR has a drawback that the image quality in that state is deteriorated because the data generation amount is controlled to be constant with respect to the case where the change amount of the image to be captured increases.
[0009]
When sending video data from a remote location to a central collection center, frame control using CBR is used, ignoring the occurrence of image degradation, in order to suppress data delay and data volume on the network. Often done. However, in this case, there are many problems with video input information at a fixed point because the change in the amount of video data to be captured is relatively small.
[0010]
However, recently, the use of a video input device mounted on a moving body has increased, and when sending via a network in this state, while reducing the amount of image data to be transmitted as much as possible, Means for maintaining or improving image quality are required.
[0011]
The present invention has been made in view of the above circumstances, and its object is to reduce factors that cause delays and data loss on the network while suppressing deterioration of the image quality of the transmitted image.
[0012]
[Means for Solving the Problems]
The present invention relates to a video input device, a speed detection unit for detecting a moving speed of the video input device, an imaging unit, and an encoding for encoding an image captured by the imaging unit into data of a fixed bit rate. Means, a transmission means for transmitting data encoded by the encoding means, and a sampling rate for encoding the image by the encoding means in a stepwise manner in accordance with the speed detected by the speed detecting means. Changing means for changing to a predetermined range for the moving speed, and when the moving speed increases, the sampling rate is increased stepwise, and when the moving speed decreases, the changing means A video input device characterized in that the sampling rate is lowered .
[0013]
An image encoding method for a video input device, a speed detecting step for detecting a moving speed of the video input device, an encoding step for encoding an input image into fixed bit rate data, and the encoding step A transmission step of transmitting the data encoded in step S, and the encoding step stepwise sets a sampling rate for encoding the input image in accordance with the speed detected in the speed detection step. A step of changing , wherein the encoding step gives the moving speed a predetermined width, and when the moving speed increases, the sampling rate is increased stepwise, and when the moving speed decreases, the encoding step increases stepwise. An image encoding method for a video input device, characterized by lowering a sampling rate .
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings.
[0015]
FIG. 1 is a conceptual diagram of a “video input system” according to an embodiment of the present invention.
[0016]
A video input device 103 equipped with a GPS navigation device using radio waves from the GPS satellite 101 and a receiving antenna 102 are installed in this image input device.
[0017]
The image of the image input device is sent to the information collection center 105 via the network 104. In the information collection center 105, it is possible to view videos of a plurality of video input devices 103 connected via the network 104. Although not described in this, it is assumed that the image input terminal 103 is mounted on a moving object such as a car and is connected to the network 104 by radio or the like. Similarly, 105 may be connected via wireless.
[0018]
FIG. 2 shows a functional block configuration for explaining specific functions in the video input device 103.
[0019]
First, a GPS receiving unit 201 to which a signal input from the GPS receiving antenna 102 described in FIG. 1 is input, a position detecting unit 202 that detects position data from the GPS receiving unit 201, and 202 at a certain time interval. The position storage unit 203 that stores the value of the position detection unit and the position storage unit 203 store a certain amount of data, but store position detection data up to the previous time.
[0020]
Next, the speed detection unit 204 has a function of detecting the moving speed of the image input device 103 by comparing the previously measured position detection data from the position storage unit 203 with the currently measured position detection data.
[0021]
The speed detection unit 204 has a function of storing speed data relating to the movement of 103 detected this time.
[0022]
Next, the system processing unit 205 is a processing unit that performs general control of the image input apparatus 103, and includes a processor, a memory, a register, and the like.
[0023]
In addition to the description from the position information input unit such as GPS, the other image input unit will be described.
[0024]
A video data signal 207 obtained by imaging an external landscape or the like is first input to the video signal processing unit 208 and subjected to analog signal processing. Next, the video signal encoding unit 209 generates compression encoded data of a fixed bit rate such as MPEG2, which is a video predictive encoding / compression unit, from the input video analog signal. After the data is generated, the video signal output unit 210 outputs the multiplexed data such as a transport stream (TS) to the network 104 described with reference to FIG.
[0025]
Next, the video compression rate control unit 206 will be described. The encoding sampling rate table preset in 206 for that purpose will be described first with reference to FIGS.
[0026]
The encoding sampling table has a certain moving speed width (range) with respect to the moving speed of the image input device 103 and corresponds to this moving speed, as shown in the encoding sampling rate table example 1 in FIG. An encoding sampling table for setting a fixed bit rate for the encoded video is set. More specifically, as shown in FIG. 4, there is a preset value of the encoding sampling rate corresponding to the range that is the width of the moving speed at which the image input device 103 moves. In order to perform compression encoding, there is a table including corresponding setting values for setting the encoder in the video signal encoding unit 209. For example, if it exceeds 100 km, the sampling rate is set to the value “M”, so that the value “m” is obtained as the setting value of the encoder.
[0027]
Next, details of the video compression rate control unit 206 will be described.
[0028]
The video compression rate control unit 206 has a function of setting the value obtained from the above-described FIG. 4 table in the video compression rate control unit 206 in the encoder in 209 for the data from the speed detection unit 204.
[0029]
Further, since the moving speed width (range) described with reference to FIGS. 3 and 4 exists in the video compression rate control unit 206 when performing the above-described setting function, it is determined whether the setting value needs to be changed. Have the means to Therefore, calling the moving speed information of the current image input apparatus 103 stored in the 204 mentioned above, or is within a predetermined range of the moving speed range of FIG. 4, detects whether the determination has shifted to the next range Has the function of
[0030]
This completes the description of the functional configuration of the video input device.
[0031]
The flow chart of FIG. 5 describes the video compression / encoding rate control as an operation flow centered on the system processing unit 205 in order to perform these series of controls. Next, FIG. 5 will be described.
[0032]
First, in the above-described 205 system processing unit, a predetermined time 501 is measured, and a predetermined elapsed time set in advance is determined in 502. If this time has not been reached, the process returns to the determination of 502 again. If the predetermined time has been reached, the process proceeds to the next step 503.
[0033]
In 503, the image input terminal 103 detects the value of the position detection unit 202 in order to detect the position at that time. Then, storage processing is performed in the position storage unit 203. This value is the Nth value. Next, in step 504, as a process of the above-described speed detection unit 204, a difference from the previous (N-1) th position information is obtained. Due to the difference per fixed time, a moving speed of 103 is obtained. Further, this is stored at 505 as the Nth moving speed detection data. This is specifically performed by the speed detector at 204 described above.
[0034]
Next, in step 506, the speed data when the speed is the previous (N-1) and the difference value are compared and determined. That is, it is a judgment whether it is in the moving speed range shown in FIG.
[0035]
If it is within the predetermined value that falls within the range width, the process returns to step 502, and the process enters the speed detection process flow again.
[0036]
If the moving speed range is changed beyond the predetermined value, the process proceeds to step 507.
[0037]
In step 507, the encoder setting is obtained in order to obtain an encoded sampling rate corresponding to the moving speed range using the table of FIG. 4 as described above. This operation is specifically performed by the video compression rate control unit 206.
[0038]
Next, in step 508, the set value is acquired. In step 509, the process proceeds to a process for changing the video coding rate of the encoder. These processes are also specifically the above-described 206 video compression rate control unit and 209 video signal encoding unit.
[0039]
By the work described in the operation flow of the present embodiment, the video compression encoding rate of the video input device 103 changes following the change in the moving speed.
[0040]
Normally, in MPEG2, the control is in the range of 3 Mbps to 15 Mbps.
[0041]
Further, in the decoding of the video data in the information collection center 105 connected on the network corresponding to the video input device 103 described in FIG. 1, the above-mentioned transport stream (TS) received sequentially is controlled. By recognizing the bit rate information in the compression encoded data, the decoding operation that successively follows the rate is continuously performed.
[0042]
In this embodiment, an example of means for detecting the moving speed of the image input device by position detecting means using a GPS satellite has been shown. However, the portion up to detecting the moving speed is also described in the claims. It can be performed using means such as an acceleration sensor. In this case as well, control is performed by managing the value of the acceleration sensor monitored for a certain time. Accordingly, the table shown in FIG. 4 corresponds to the acceleration sensor, so that there is a range width of the acceleration sensor, which is a set value corresponding to this value. And it implement | achieves by performing the setting value change work of this value.
[0043]
As is clear from the above description, in the video input device having means for detecting the moving speed of the video input device using the position detection of the video input device mounted on the movable object, the acceleration sensor, etc. Amount of data sent over a network to a remote information collection center having means for making the video signal coding rate variable in bit rate (CBR) video compression coding according to the moving speed of the video input device Is dynamically changed according to the moving speed of the image input device, thereby improving or maintaining the image quality of the image to be sent, and eliminating the cause of delay and data loss on the network.
【The invention's effect】
By changing the sampling rate for encoding the image to the fixed bit rate data according to the moving speed in steps, the image quality of the transmitted image is degraded rather than always encoding at the same sampling rate. It is possible to reduce the delay and data loss on the network rather than immediately encoding at a variable bit rate following the moving speed .
[Brief description of the drawings]
FIG. 1 is a conceptual diagram of a video input system.
FIG. 2 is a diagram illustrating a functional configuration of a video input device.
FIG. 3 is an explanatory diagram for creating a sampling control table for video encoding.
FIG. 4 is a diagram illustrating a specific example of a sampling control table for video encoding.
FIG. 5 is a flowchart showing the operation of the exemplary embodiment of the present invention.
FIG. 6 is a diagram illustrating an example of a general frame flow for image compression coding.
[Explanation of symbols]
101 GPS Satellite 102 Reception Antenna 103 Video Input Device 104 Network 105 Information Collection Center 201 GPS Reception Unit 202 Position Detection Unit 203 Position Storage Unit 204 Speed Detection Unit 205 System Processing Unit 206 Video Compression Rate Control Unit 207 Video Data Signal 208 Video Signal Processing Unit 209 video signal encoding unit 210 video signal output unit

Claims (3)

A video input device,
Speed detecting means for detecting the moving speed of the video input device;
Encoding means for encoding an input image into data of a fixed bit rate;
Transmitting means for transmitting the data encoded by the encoding means;
Changing means for stepwise changing a sampling rate for encoding an image by the encoding means in accordance with the speed detected by the speed detecting means, and the changing means sets the moving speed to the moving speed. A video input apparatus having a predetermined width, wherein the sampling rate is increased stepwise when the moving speed is increased, and the sampling rate is decreased stepwise when the moving speed is decreased .   The video input device according to claim 1, wherein the speed detection unit detects a moving speed of the video input device based on a change in position of the video input device every predetermined time. An image encoding method for a video input device, comprising:
A speed detecting step for detecting a moving speed of the video input device;
An encoding process for encoding the input image into data of a fixed bit rate;
A transmission step of transmitting the data encoded in the encoding step;
Have
The encoding step is a step of stepwise changing a sampling rate for encoding the input image according to the speed detected in the speed detection step, and the encoding step includes the moving speed. And a predetermined width, and the sampling rate is increased stepwise when the moving speed is increased, and the sampling rate is decreased stepwise when the moving speed is decreased . Method.