The commonly sold Web cameras are connectable either via the USB
to specific computer, or independent IP
cameras connected via Wi-Fi
The advantages and disadvantages:
The USB Web camera is the cheapest solution but it must be located near the PC, requires the installation of WDM or BDA drivers, that are not always 100% reliable, requires additional software for displaying or streaming the captured images, and while streaming, the images are delayed 3 - 10 seconds compared to reality.
For the IP camera the higher price is the main disadvantage, but it is independent on the PC and the distance is also not the issue, the supplied software or the images provided via the network can be easily integrated in the PROMOTIC system, it is more reliable, and suffers minimal image delays.
From the practical point of view, we therefore recommend the usage of Web IP cameras
in the PROMOTIC system.
WebCam - USB
The cameras connectable via the USB
require the installation of WDM
drivers created by the manufacturer of the specific device (similar as for PC TV cards, etc.). But in OS Windows
, there is no default application, able to use such drivers and display the captured images. One possible solution is to use some software (VLC media player), that can connect to such drivers, convert the captured video into some known format (WMV), and offer that video on specified IP address
into the LAN
network in the form of streamed video. When receiving such stream, we follow the same way as for the RSTP
protocol described below.
WebCam - Lan (IP)
The manufacturers of these devices are also providing the corresponding software. The software is usually used for detecting the IP address of the camera via Web interface. After the camera is detected, the software can be used for controlling the cameras (zoom, turning, ...) and additional parameters. The software may also contain ActiveX
item for displaying the streamed video. The network device can also act as Web server, offering Web pages (on its IP address) containing the streamed video. If the current type supports RTSP
(Real Time Streaming Protocol
), then the video can be displayed in arbitrary stream viewer (WMP, Winamp
...). If the current type supports FTP
(File Transfer Protocol
), then it is possible to save the stream into the file(s).
The possible options of displaying the streamed video in the PROMOTIC application:
- if the ActiveX item displaying the streaming video is available:
In the panel of PROMOTIC application, "Preconfiguration PmgActiveX "ActiveX - General"" is selected. In the "ProgID" configurator, the corresponding ActiveX is selected and its interface is used in order to connect to the camera's IP address (tested with Air Live WL-5400CAM).
- if the RTSP protocol is supported:
1) Windows media player
In the panel of PROMOTIC application, "Preconfiguration PmgActiveX "ActiveX - General"" is selected. In the ActiveX objects list the Windows media player is selected and its properties menu is used for setting the camera's URL address (the url entry).
Another option is to create own HTML page containing the Windows media player plugin with the connection to a specific address. This page can be then offered by the PmaWebDir object and also displayed by the PmaReport object.
Example of the HTML page:
for connecting the Windows Media Player plugin to a stream on the IP address 10.131.184.70 and port 8090
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
var oVideoPlayer = '<embed id="tgPlugin" type="application/x-mplayer2" pluginspage="http://www.microsoft.com/windows/mediaplayer/" src="http://10.131.184.70:8090" width="640" height="480" hidden="false" showstatusbar="1" showcontrols="1" autostart="true"></embed>';
2) VLC player
Another option is to use the ActiveX VideoLAN.VLCPlugin
object that can be installed to computer together with the VLC playeru
installation. In the panel, then select the PmgActiveX
object that connects to this plugin. In the onStart
event of this object then set the connection to RTSP
stream as follows:
VLC plugin - connecting the RTSP stream:
var oPlayer = pMe.Acx;
oPlayer.volume = 50;
oPlayer.Toolbar = false;
- If the camera offers the Web page containing the streaming video on its IP address:
The PmaReport object can be used for displaying the desired page.