CN105262970B - A kind of packaging method based on view data and system - Google Patents

Abstract

The invention discloses an image data-based encapsulation method and system of the present invention. The method includes: storing image data to be encapsulated in a cache; calculating the image to be encapsulated according to the total amount of current frame image data in the cache Data length: according to the calculated length of the image data to be packaged, the image data is packaged and packaged. The system includes storage unit, length calculation unit and encapsulation unit. The present invention takes into account the uncertain characteristics of the Ethernet frame format and the total amount of JPEG image frame data when encapsulating, and dynamically calculates the length of the image data to be packaged, thereby effectively avoiding the need to fill invalid data and greatly reducing data processing costs. time, reduce the occupation of network bandwidth, and the invention is simple to implement, requires less equipment, can effectively shorten the development cycle, and save costs. The invention can be widely used in the field of data encapsulation.

Description

A packaging method and system based on image data

technical field

The invention relates to the technical field of data encapsulation, in particular to an encapsulation method and system based on image data.

Background technique

JPEG is a static image compression coding standard formulated under the leadership of the International Organization for Standardization (ISO). Under the background of large amount of image data and people's higher and higher requirements for image quality, JPEG is a low-complexity, high-compression ratio Image compression standards have been widely used in the fields of multimedia with a huge amount of data and network transmission with precious bandwidth. As a data transmission standard, Ethernet is the most widely used network technology at present because it is simple to implement, low in price, and can realize high-speed, stable, and real-time transmission of image data.

In industrial sites, due to various extreme environments and specific application requirements, real-time image acquisition of industrial equipment or sites is usually required. At present, most domestic image acquisition solutions used in the field of video surveillance are realized by CCD image sensor + video decoder (such as SAA7113H) + FPGA/CPLD + DSP. However, this kind of existing scheme generally has a long development cycle, and in the existing general-purpose image acquisition and processing system, it is necessary to use a frame buffer module to store the entire frame or multiple frames of image data, and the storage device generally adopts SDRAM, SRAM, etc. Such a high-capacity high-speed memory device has a relatively high cost.

Contents of the invention

In order to solve the above technical problems, the object of the present invention is to provide a packaging method and system based on image data that can shorten the development cycle and save costs.

The technical scheme adopted in the present invention is:

A packaging method based on image data, comprising the following steps:

A. Store the image data to be encapsulated in the cache;

B. According to the total amount of the current frame image data in the cache, calculate the length of the image data to be encapsulated;

C. Packing and packing the image data according to the calculated length of the image data to be packed.

As a further improvement of the encapsulation method based on image data, K represents the minimum allowed packet length, and the maximum allowed packet length is 2K, and C represents the number of header and tail bytes added in the packet The sum, M represents the total amount of image data in the current frame in the cache, and N represents the length of the image data to be encapsulated;

Then said step B comprises:

B1. If M≥3K-2C, calculate the corresponding length of image data to be packaged N=2K-C;

B2. If 2K-C<M≤3K-2C and M is an odd number, calculate the corresponding image data length N=(M+1)/2 to be packaged;

B3. If 2K-C<M≤3K-2C and M is an even number, calculate the corresponding length of image data to be packaged N=M/2;

B4. If K-C<M≤2K-C, then calculate the corresponding length of image data to be packaged N=M;

B5. If M<K-C, calculate the corresponding length of image data to be packaged N=0.

As a further improvement of the encapsulation method based on image data, the step C includes:

C1. According to the calculated length of the image data to be packaged, take out the image data of the corresponding length from the buffer and pack it;

C2. According to the image data taken out, configure the corresponding packet header and packet tail;

C3. Encapsulate the packaged image data according to the format of packet header-image data-packet trailer.

As a further improvement of the encapsulation method based on image data, the packet header includes effective length and packet type.

As a further improvement of the encapsulation method based on image data, the packet tail is a check code.

Another technical scheme adopted in the present invention is:

A packaging system based on image data, including:

The storage unit is used to store the image data to be encapsulated in the cache;

The length calculation unit is used to calculate the length of the image data to be encapsulated according to the total amount of the current frame image data in the cache;

The packaging unit is configured to package and package the image data according to the calculated length of the image data to be packaged.

As a further improvement of the encapsulation system based on image data, let K represent the minimum allowed packet length, and take the allowed maximum packet length as 2K, and C represent the number of header and tail bytes added in the packet The sum, M represents the total amount of image data in the current frame in the cache, and N represents the length of the image data to be encapsulated;

Then the length calculation unit includes:

The first judging calculation unit is used to calculate the corresponding required packaged image data length N=2K-C if M≥3K-2C;

The second judging calculation unit is used to calculate the corresponding required packaged image data length N=(M+1)/2 if 2K-C<M≤3K-2C and M is an odd number;

The third judging calculation unit is used to calculate the corresponding required packaged image data length N=M/2 if 2K-C<M≤3K-2C and M is an even number;

The fourth judging calculation unit is used to calculate the corresponding required packaged image data length N=M if K-C<M≤2K-C;

The fifth judging calculation unit is configured to calculate the corresponding length N=0 of the image data to be packaged if M<K-C.

As a further improvement of the encapsulation system based on image data, the encapsulation unit includes:

The packaging unit is used to take out the image data of the corresponding length from the buffer for packaging according to the calculated length of the image data to be packaged;

The configuration unit is used to configure the corresponding packet header and packet tail according to the image data taken out;

The encapsulation execution unit is used for encapsulating the packaged image data according to the format of packet header-image data-packet trailer.

The beneficial effects of the present invention are:

An image data-based encapsulation method and system of the present invention take into account the uncertain characteristics of the Ethernet frame format and the total amount of JPEG image frame data during encapsulation, and dynamically calculate the length of the image data to be packaged, thereby effectively avoiding the need for filling In the case of invalid data, the time for data processing is greatly reduced, the occupation of network bandwidth is reduced, and the present invention is simple to implement, requires less equipment, can effectively shorten the development cycle, and save costs.

Description of drawings

The specific embodiment of the present invention will be further described below in conjunction with accompanying drawing:

Fig. 1 is a flow chart of steps of a packaging method based on image data in the present invention;

Fig. 2 is a step flow chart of step C of a packaging method based on image data in the present invention;

Fig. 3 is a block diagram of modules of a packaging system based on image data in the present invention;

Fig. 4 is a schematic diagram of the packet text format of the data encapsulation packet of the present invention;

Fig. 5 is the system functional block diagram of the realization process of the present invention;

Fig. 6 is the FPGA functional module realization block diagram of the present invention's realization process;

Fig. 7 is a FPGA implementation block diagram of the encapsulation method in the implementation process of the present invention.

Detailed ways

With reference to Fig. 1, a kind of packaging method based on image data of the present invention comprises the following steps:

A. Store the image data to be encapsulated in the cache;

B. According to the total amount of the current frame image data in the cache, calculate the length of the image data to be encapsulated;

C. Packing and packing the image data according to the calculated length of the image data to be packed.

Further as a preferred embodiment, let K represent the minimum packet length allowed, and get the maximum packet length allowed to be 2K, C represents the sum of the header and tail bytes added in the packet, and M represents the current frame in the cache The total amount of image data, N represents the length of image data to be packaged;

Then said step B comprises:

B1. If M≥3K-2C, calculate the corresponding length of image data to be packaged N=2K-C;

B2. If 2K-C<M≤3K-2C and M is an odd number, calculate the corresponding image data length N=(M+1)/2 to be packaged;

B3. If 2K-C<M≤3K-2C and M is an even number, calculate the corresponding length of image data to be packaged N=M/2;

B4. If K-C<M≤2K-C, then calculate the corresponding length of image data to be packaged N=M;

B5. If M<K-C, calculate the corresponding length of image data to be packaged N=0.

Referring to Fig. 2, further as a preferred embodiment, the step C includes:

C1. According to the calculated length of the image data to be packaged, take out the image data of the corresponding length from the buffer and pack it;

C2. According to the image data taken out, configure the corresponding packet header and packet tail;

C3. Encapsulate the packaged image data according to the format of packet header-image data-packet trailer.

Referring to FIG. 4 , as a further preferred implementation manner, the packet header includes an effective length and a packet type. The tail of the packet is a check code.

Wherein, the effective length indicates the number of effective data bytes of the data encapsulation package, which is the sum of the number of bytes of the packet type, image data and check code. At the data receiving end, first receive this byte, and then according to this word The instructions in the section determine the length of the received data; the packet type is mainly used to indicate the data source or purpose, such as 0x01 indicates the data of the camera 1, and 0x02 indicates the data of the camera 2; the image data indicates the JPEG data that actually needs to be transmitted; Check code, a 16-bit CRC check code generated according to the image data, used by the receiving end to check the received packet data, when the check fails, the error packet statistics are performed and the current image frame is processed accordingly .

With reference to Fig. 3, a kind of encapsulation system based on image data of the present invention comprises:

The storage unit is used to store the image data to be encapsulated in the cache;

The length calculation unit is used to calculate the length of the image data to be encapsulated according to the total amount of the current frame image data in the cache;

The packaging unit is configured to package and package the image data according to the calculated length of the image data to be packaged.

As a further improvement of the encapsulation system based on image data, let K represent the minimum allowed packet length, and take the allowed maximum packet length as 2K, and C represent the number of header and tail bytes added in the packet The sum, M represents the total amount of image data in the current frame in the cache, and N represents the length of the image data to be encapsulated;

Then the length calculation unit includes:

The first judging calculation unit is used to calculate the corresponding required packaged image data length N=2K-C if M≥3K-2C;

The second judging calculation unit is used to calculate the corresponding required packaged image data length N=(M+1)/2 if 2K-C<M≤3K-2C and M is an odd number;

The third judging calculation unit is used to calculate the corresponding required packaged image data length N=M/2 if 2K-C<M≤3K-2C and M is an even number;

The fourth judging calculation unit is used to calculate the corresponding required packaged image data length N=M if K-C<M≤2K-C;

The fifth judging calculation unit is configured to calculate the corresponding length N=0 of the image data to be packaged if M<K-C.

As a further improvement of the encapsulation system based on image data, the encapsulation unit includes:

The packaging unit is used to take out the image data of the corresponding length from the buffer for packaging according to the calculated length of the image data to be packaged;

The configuration unit is used to configure the corresponding packet header and packet tail according to the image data taken out;

The encapsulation execution unit is used for encapsulating the packaged image data according to the format of packet header-image data-packet trailer.

When encapsulating the data, the determination of the length of the encapsulation package should take into account the uncertain characteristics of the Ethernet frame format and the total amount of JPEG image frame data. When taking a fixed-length slice (such as 256Byte) for a JPEG image frame, because the total amount of frame data is uncertain, the length of the last slice is also uncertain, so that there will be an image packet lower than 46Byte. There are two common processing methods: one is when encapsulating data fragments, the length of the encapsulation packet is constant, and there are fragments that do not meet the length. When encapsulating the data packet, invalid data is filled to make it meet the specified length ; Another method is to send directly, invalid data automatically filled by the Ethernet side. Both of the above two methods have invalid data filling, which increases the data processing time and wastes the Ethernet bandwidth. In order to avoid the occurrence of packets smaller than 46Byte, this system proposes a data encapsulation method with variable length to achieve more efficient data transmission.

Specific embodiments of the present invention are as follows:

In the embodiment of the present invention, if the allowed minimum packet length K is 128 Byte, then the allowed maximum packet length 2K is 256 Byte, and the sum C of the header and tail bytes added in the packet is 4 Byte, and M represents The total amount of image data in the current frame in the cache, and N represents the length of the image data to be encapsulated.

S1. Store the image data to be encapsulated in the cache;

S2. According to the total amount of the current frame image data in the buffer, calculate the length of the image data to be encapsulated, specifically as follows:

If M≥376 Byte, calculate the corresponding required packaged image data length N=252 Byte;

If 252 Byte<M≤376 Byte and M is an odd number, calculate the corresponding length of image data to be packaged N=(M+1)/2;

If 252 Byte<M≤376 Byte and M is an even number, then calculate the corresponding required packaged image data length N=M/2;

If 124 Byte<M≤252 Byte, then calculate the corresponding length of the image data to be packaged N=M;

If M<124 Byte, then calculate the corresponding image data length N=0 that needs to be encapsulated, which means that no data encapsulation operation is performed at this time;

S3. According to the calculated length of the image data to be packaged, the image data of the corresponding length is taken out from the buffer and packed;

S4. According to the image data taken out, configure the corresponding packet header and packet tail;

S5. Encapsulate the packaged image data according to the packet header-image data-packet trailer format.

The realization process of the present invention under FPGA environment is as follows:

The system realizes the image acquisition function of dual cameras. After the camera image data is collected and processed by the FPGA, it is transmitted to the host computer via Ethernet. The host computer decodes the received JPEG data and displays it in real time. At the same time, the host computer also has the configuration or control function for the lower computer. The system function block diagram is shown in the figure 5.

The realization block diagram of the FPGA function module is shown in Figure 6. When the system is working, the W5300 configuration module completes the configuration of the W5300, realizes the Ethernet communication of the TCP protocol, and then the PC host computer sends configuration commands to the FPGA through the Ethernet, and the FPGA Analyze the configuration command and complete the configuration of the two-way OV2640 camera. OV2640 outputs JPEG image data according to the specific configuration, and then the FPGA completes the segmentation and packaging of the image data. The processed two-way image data is finally transmitted via Ethernet The upper computer can display the image separately, and the upper computer can send control commands at any time while displaying the image in real time, and through the analysis of the instruction analysis module, it can complete functions such as pausing the reception of a certain image, changing the image output resolution, and frame rate.

The data encapsulation module completes the fragmentation and encapsulation of image frames, and converts the collected original image frame data into several image envelopes, which is the core of encapsulating envelopes based on image slices. The implementation of this module will be described below.

In the FPGA, two FIFOs are used to cache the two-way image data respectively. In the specific implementation, the values of K and C in the variable-length data encapsulation method and the width and depth of the FIFO are all parameterized, which can be easily adjusted. The format of the data encapsulation packet. When this system is implemented, the value of K is 128Byte. Considering certain data burst factors, the depth of a single FIFO is 1024, and the width is 10 (1 bit for the start and end of the frame, and 8 bits for image data). The realization block diagram is shown in Figure 7.

In the above method, the read and write sides of the data cache are independent of each other and can be performed simultaneously, which conforms to the feature that the image data arrives at any time, so the data segment packaging will not affect the transmission speed of the image data. However, it should be noted that M, which is encapsulated with the aforementioned indefinite length data, is the total amount of data in the current frame, not the total amount of data in the cache, because the image data comes at any time, if the current image frame data has not been encapsulated, and the next When a frame image comes again, there will be two frames of image data in the cache.

The dynamic packet length module is realized according to the aforementioned variable-length data encapsulation algorithm. In the FPGA, it generates the read FIFO data length value based on whether the data encapsulation module is free and the data volume of the current image frame in the FIFO, because the system has two FIFOs, and the read FIFO should be selected according to the data volume in the specific FIFO during implementation. , if the data in the two FIFOs all meet the data fetching requirements, the two FIFOs are selected in turn. After the read FIFO and the amount of read data are determined, the FIFO outputs the image data of the specified length according to the given length value; the CRC16 code generation module generates the CRC16 check code of the output image data; finally, the image data is added to the corresponding image data by the data encapsulation module Packet header and packet tail generate image packet text. In this way, the complete fragmentation and encapsulation of a frame of data is completed.

Finally, the image frame data is transmitted to the W5300 interface in units of image packets, and transmitted to the host computer via Ethernet. The host computer extracts the image data according to the data encapsulation protocol of the sending end, and reorganizes the data fragments, and finally reorganizes the JPEG image The frame is decoded and displayed in real time to complete the image acquisition task.

As can be seen from the foregoing, a kind of encapsulation method and system based on image data of the present invention considers the uncertain characteristics of the Ethernet frame format and the total amount of JPEG image frame data during encapsulation, and dynamically calculates the length of the image data to be packaged, thereby It can effectively avoid the situation that invalid data needs to be filled, greatly reduce the time for data processing, and reduce the occupation of network bandwidth, and the invention is simple to implement, requires less equipment, can effectively shorten the development cycle, and save costs.

The above is a specific description of the preferred implementation of the present invention, but the invention is not limited to the described embodiments, and those skilled in the art can also make various equivalent deformations or replacements without violating the spirit of the present invention. , these equivalent modifications or replacements are all within the scope defined by the claims of the present application.

Claims (6)

1. a kind of packaging method based on view data, which comprises the following steps:

A, the image data encapsulated will be needed to be stored in caching；

B, according to the current frame image total amount of data in caching, the image data length of encapsulation needed for being calculated；

C, according to the image data length for the required encapsulation being calculated, image data is packaged and is encapsulated；

If K indicates the most parcel text length allowed, and taking the maximum text length of wrapping of permission is 2K, and C indicates the packet of Bao Wenzhong addition The sum of head and packet trail byte number, M indicate current frame image total amount of data in caching, the image data length encapsulated needed for N expression；

Then the step B includes:

If B1, M >=3K-2C, the corresponding required image data length N=2K-C encapsulated is calculated；

If B2,2K-C < M < 3K-2C and M be odd number, calculate it is corresponding needed for encapsulate image data length N=(M+1)/ 2；

If B3,2K-C < M < 3K-2C and M are even number, the corresponding required image data length N=M/2 encapsulated is calculated；

If B4, K-C≤M≤2K-C, the corresponding required image data length N=M encapsulated is calculated；

If B5, M < K-C, the corresponding required image data length N=0 encapsulated is calculated.

2. a kind of packaging method based on view data according to claim 1, it is characterised in that: the step C includes:

C1, according to the image data length of required encapsulation being calculated, taken out from buffering the image data of corresponding length into Row is packaged；

C2, the image data according to taking-up, corresponding packet header and packet tail are configured to it；

C3, according to packet header-image data-packet tail format, the image data after packing is packaged.

3. a kind of packaging method based on view data according to claim 2, it is characterised in that: the packet header includes Imitate length and Bao Wen type.

4. a kind of packaging method based on view data according to claim 2, it is characterised in that: the packet tail is verification Code.

5. a kind of package system based on view data characterized by comprising

Storage unit, for the image data for needing to encapsulate to be stored in caching；

Length computation unit, the picture number for being encapsulated needed for according to the current frame image total amount of data in caching, being calculated According to length；

Encapsulation unit is packaged image data and is sealed for the image data length according to the required encapsulation being calculated Dress；

If K indicates the most parcel text length allowed, and taking the maximum text length of wrapping of permission is 2K, and C indicates the packet of Bao Wenzhong addition The sum of head and packet trail byte number, M indicate current frame image total amount of data in caching, the image data length encapsulated needed for N expression；

Then the length computation unit includes:

First judges computing unit, if being used for M >=3K-2C, calculates the corresponding required image data length N=2K- encapsulated C；

Second judges computing unit, if being used for 2K-C < M < 3K-2C and M as odd number, calculates the corresponding required image encapsulated Data length N=(M+1)/2；

Third judges computing unit, if being used for 2K-C < M < 3K-2C and M as even number, calculates the corresponding required image encapsulated Data length N=M/2；

4th judges computing unit, if being used for K-C≤M≤2K-C, calculates the corresponding required image data length N=encapsulated M；

5th judges computing unit, if being used for M < K-C, calculates the corresponding required image data length N=0 encapsulated.

6. a kind of package system based on view data according to claim 5, it is characterised in that: the encapsulation unit packet It includes:

Packaged unit takes out corresponding length for the image data length according to the required encapsulation being calculated from buffering Image data is packaged；

Configuration unit configures corresponding packet header and packet tail to it for the image data according to taking-up；

Execution unit is encapsulated, for being packaged to the image data after packing according to packet header-image data-packet tail format.