USB Camera handler (ucam://)

What is the USB Camera handler

TQLEngine provides a protocol handler wrapper to interact with USB Camera. USB Camera are handy actuators for home monitoring, taking one off pictures etc.

High frame rate MJPEG 60 fps @ 1280 (H) x 720 (V) , 30 fps @ 1920 (H) x 1080 (V)
CMOS 1080P sensor for high quality image and low power consumption
high pixel technology for sharp image and accurate color reproduction
low light performance - ideal for any lighting condition
UVC for use in Linux, Windows XP, WIN CE, MAC, SP2 or above

USB Camera Parameters

Parameter Name	Description
USBCameraParameters.ImageFormat	Specify image format. Example: jpeg
USBCameraParameters.SaveToDisk	Do you want the image file to be saved to disk?. Value is either true or false
USBCameraParameters.ImageName	Specify the file name to be used when saving to the disk. The file gets saved in the current folder in which TQLEngine is running
USBCameraParameters.Size.Height	Image height. An integer value
USBCameraParameters.Size.Width	Image width. An integer value.
USBCameraParameters.Configuration.Standard	Standard value of image
USBCameraParameters.Configuration.Quality	Quality of image
USBCameraParameters.Configuration.Channel	The acquisition channel. Default is 0
USBCameraParameters.Configuration.Brightness	Brightness of video image (0-255)
USBCameraParameters.Configuration.Contrast	Contrast of image (0-255).
USBCameraParameters.Configuration.Gamma	Gamma of image
USBCameraParameters.Configuration.Gain	Gain of image
USBCameraParameters.Configuration.Sharpness	Sharpness of image (0-255).
USBCameraParameters.Configuration.Saturation	Saturation of image (0-255).
USBCameraParameters.Configuration.Hue	Hue of image

USB Camera Parameter Structure

USB Camera Parameter Structure

<USBCameraParameters>
  <ImageFormat></ImageFormat>
  <SaveToDisk></SaveToDisk>
  <ImageName></ImageName>
  <Size>
    <Height></Height>
    <Width></Width>
  </Size>
  <Configuration>
    <Standard></Standard>
    <Quality></Quality>
    <Channel></Channel>
    <Brightness></Brightness>
    <Contrast></Contrast>
    <Gamma></Gamma>
    <Gain></Gain>
    <Sharpness></Sharpness>
    <Saturation></Saturation>
    <Hue></Hue>
  </Configuration>
</USBCameraParameters>

Invoking UCAM Handler

Invoking UCAM Handler via Invoke

<Action Name="USBCameraImageAction">
  <Workflow Limit="1" Live="1" Timeout="-1">
    <Task name="Main" while="true">
      <Event name="Argument" as="ActionArgument"/>
      <Invoke name="GetImage" waitFor="ActionArgument" post="ucam://">
        <Message>
          <Value>
            <USBCameraParameters>
              <ImageFormat>[%:Event.Argument.USBCameraParameters.ImageFormat.Value:%]</ImageFormat>
              <SaveToDisk>[%:Event.Argument.USBCameraParameters.SaveToDisk.Value:%]</SaveToDisk>
              <ImageName>[%:Event.Argument.USBCameraParameters.ImageName.Value:%]</ImageName>
              <Size>
                <Height>[%:Event.Argument.USBCameraParameters.Size.Height.Value:%]</Height>
                <Width>[%:Event.Argument.USBCameraParameters.Size.Width.Value:%]</Width>
              </Size>
              <Configuration>
                <Standard>[%:Event.Argument.USBCameraParameters.Configuration.Standard.Value:%]</Standard>
                <Quality>[%:Event.Argument.USBCameraParameters.Configuration.Quality.Value:%]</Quality>
                <Channel>[%:Event.Argument.USBCameraParameters.Configuration.Channel.Value:%]</Channel>
                <Brightness>[%:Event.Argument.USBCameraParameters.Configuration.Brightness.Value:%]</Brightness>
                <Contrast>[%:Event.Argument.USBCameraParameters.Configuration.Contrast.Value:%]</Contrast>
                <Gamma>[%:Event.Argument.USBCameraParameters.Configuration.Gamma.Value:%]</Gamma>
                <Gain>[%:Event.Argument.USBCameraParameters.Configuration.Gain.Value:%]</Gain>
                <Sharpness>[%:Event.Argument.USBCameraParameters.Configuration.Sharpness.Value:%]</Sharpness>
                <Saturation>[%:Event.Argument.USBCameraParameters.Configuration.Saturation.Value:%]</Saturation>
                <Hue>[%:Event.Argument.USBCameraParameters.Configuration.Hue.Value:%]</Hue>
              </Configuration>
            </USBCameraParameters>
          </Value>
        </Message>
      </Invoke>
      <Log Message="******Invoked USBCamera******"/>
      <Output name="Result" as="ActionResult">
        <Value>
          <Image>[%:[%:@Output:%]Invoke.GetImage.Message.Value:%]</Image>
        </Value>
      </Output>
    </Task>
  </Workflow>
</Action>

Driver Installation Steps

For the ucam handler to work two things are needed, the video driver of the camera which comes by default and some prerequisite libraries which are shown below.

libjpeg8-dev
libv4l-dev

If you are running debian based operating system use the following commands

sudo apt-get install libjpeg8-dev

sudo apt-get install libv4l-dev

Refer to TQL CLI Protocol Install section for installation of USB Camera driver.