1, the operating system In fact, the development of the operating system is a very difficult technical problem, listed as the core technology is not an exaggeration, but because of the difficulty is too great, just for the development of video servers and the development of the operating system on the DM642 cost too much. Therefore, we suggest that there are two options: (1) Purchase TI's third-party operating system. There are already TI third parties that can provide the Linux operating system on the DM642. However, the details are not yet clear.
2. Use TI's BIOS
The BIOS is a very small core that provides the most basic functions of the operating system. Users can develop applications on it. However, development and debugging are relatively difficult. Considering the cost of development and the availability of the operating system, we chose TI
3, access control of network video server resources In order to meet the actual needs of monitoring, the general need to increase the serial port, alarm I / O, hard disk and other resources on the video server, because the network is not *, so how can *, The timely and efficient control access to these resources is a very important issue. We have specifically formulated the NRCAP agreement to solve these problems. With regard to the details of the agreement, interested readers can contact us.
4, NAT problem Because the actual situation of the network is very different, the user's needs are various, it is easy to encounter the problem of the LAN and the Internet in the same system, then how to address the network address and the conversion of the network address in the gateway Must be considered. It is generally difficult to provide a unified solution suitable for various situations, so developers need to define several solutions for the most common network conditions for the user to choose.
5, audio and video synchronization because of the inherent characteristics of network transmission, voice data and video data from the network video server to the client can not be uniform, if the client does not do any correction processing, it is difficult to ensure the synchronization of audio and video output. Generally, time stamp information can be embedded in the data packet, and the client decides the appropriate playing time of the media data according to the information. At the same time, it is emphasized that the video data is a frame-by-frame image at the end, that is, it can be considered as an isolated point on the playback time axis, and the audio data is a period, a period of data, that is, on the playback time axis. Think it is continuous, so the two media are different in the timing of synchronous playback.
6, dynamic IP
Since many users are now dial-up, the IP of the video server is dynamic in this case. How the client knows in a timely manner that the IP of the video server to be monitored is a problem that must be solved. We have defined a CDDNS protocol. After the video server is started, it will register its own information with the CDDNS server according to the CDDNS protocol. Users can obtain the IP of the video server by querying the CDDNS server.
7. Many of the scenes when moving target detection and security monitoring are usually stationary. Once there is a moving target, the user wants to be notified. In the development of detection algorithms, the selection of detection thresholds is a special issue to be studied. There are many issues to consider such as the noise of the camera, the lighting of the scene, the size and speed of the moving target.
8. Some video servers in the file system have local storage functions, which can effectively prevent the loss of important data in the event of network failure. Taking into account the versatility, it is recommended that developers choose a mainstream file system. When implemented on the DM642 platform, with the support of only TIBIOS, we implemented the FAT32 file system, which proved to be stable and user friendly. If the development company can run a successful operating system, the file system is very simple and can be considered separately.
9, automatic dial This is related to dynamic IP issues, the reason for the separate listing, because the problem is resolved and CDDNS is completely irrelevant. Developers need to develop their own dial-up protocols such as pppoe.
10, file storage format General development vendors should develop two file storage formats: special format and common format.
Users who emphasize confidentiality should generally provide a dedicated storage format. Developers can easily achieve confidentiality through a non-disclosure file format. Users who emphasize ease of use should generally store data as AVI files and then provide user-installable plug-ins.
2. Use TI's BIOS
The BIOS is a very small core that provides the most basic functions of the operating system. Users can develop applications on it. However, development and debugging are relatively difficult. Considering the cost of development and the availability of the operating system, we chose TI
3, access control of network video server resources In order to meet the actual needs of monitoring, the general need to increase the serial port, alarm I / O, hard disk and other resources on the video server, because the network is not *, so how can *, The timely and efficient control access to these resources is a very important issue. We have specifically formulated the NRCAP agreement to solve these problems. With regard to the details of the agreement, interested readers can contact us.
4, NAT problem Because the actual situation of the network is very different, the user's needs are various, it is easy to encounter the problem of the LAN and the Internet in the same system, then how to address the network address and the conversion of the network address in the gateway Must be considered. It is generally difficult to provide a unified solution suitable for various situations, so developers need to define several solutions for the most common network conditions for the user to choose.
5, audio and video synchronization because of the inherent characteristics of network transmission, voice data and video data from the network video server to the client can not be uniform, if the client does not do any correction processing, it is difficult to ensure the synchronization of audio and video output. Generally, time stamp information can be embedded in the data packet, and the client decides the appropriate playing time of the media data according to the information. At the same time, it is emphasized that the video data is a frame-by-frame image at the end, that is, it can be considered as an isolated point on the playback time axis, and the audio data is a period, a period of data, that is, on the playback time axis. Think it is continuous, so the two media are different in the timing of synchronous playback.
6, dynamic IP
Since many users are now dial-up, the IP of the video server is dynamic in this case. How the client knows in a timely manner that the IP of the video server to be monitored is a problem that must be solved. We have defined a CDDNS protocol. After the video server is started, it will register its own information with the CDDNS server according to the CDDNS protocol. Users can obtain the IP of the video server by querying the CDDNS server.
7. Many of the scenes when moving target detection and security monitoring are usually stationary. Once there is a moving target, the user wants to be notified. In the development of detection algorithms, the selection of detection thresholds is a special issue to be studied. There are many issues to consider such as the noise of the camera, the lighting of the scene, the size and speed of the moving target.
8. Some video servers in the file system have local storage functions, which can effectively prevent the loss of important data in the event of network failure. Taking into account the versatility, it is recommended that developers choose a mainstream file system. When implemented on the DM642 platform, with the support of only TIBIOS, we implemented the FAT32 file system, which proved to be stable and user friendly. If the development company can run a successful operating system, the file system is very simple and can be considered separately.
9, automatic dial This is related to dynamic IP issues, the reason for the separate listing, because the problem is resolved and CDDNS is completely irrelevant. Developers need to develop their own dial-up protocols such as pppoe.
10, file storage format General development vendors should develop two file storage formats: special format and common format.
Users who emphasize confidentiality should generally provide a dedicated storage format. Developers can easily achieve confidentiality through a non-disclosure file format. Users who emphasize ease of use should generally store data as AVI files and then provide user-installable plug-ins.
This laminated product is formed through heat pressing after electric industry alkali glass cloth dips into the phenolic resin. It has high mechanic and dielectric performance, and applicable as insulation structural components for electromechanical/electrical equipment, as well as used under damp environmental conditions and transformer oil.
Technical requirement for surface
Appearance: The surface should be smooth. Layers, arris and bubbles are not allowed. Tiny corrugation and trimming signs are allowed. Little impurity that will not affect its voltage resistance is allowed, such as irregular color, scratch and glue marks. Tiny corrugation in the inner wall is allowed. The end shall be cut tidy. The tubes with over 13mm wall thickness are allowed to have tiny flaws on the end.
Type:Phenolic Laminated Sheet, 3021 Phenolic Paper Laminated Sheet, 3025 Phenolic Cotton Laminated Sheet, Bakelite Sheet ,Phenolic Resin Panel
Phenolic Laminated Sheet
Phenolic Laminated Sheet, 3021 Phenolic Paper Laminated Sheet, 3025 Phenolic Cotton Laminated Sheet, Bakelite Sheet
SHENZHEN XIONGYIHUA PLASTIC INSULATION LTD , https://www.xyhplastic.com