video_thread module

Read video devices in a thread.

Manager module which creates a video processing thread for each video device to be used. Only for Linux devices. To be used in other modules for further processing (e.g. opticflow, QR code, streaming). Using 'cv_add_to_device' from cv.h will register a processing function and initialize the video device if necessary. Thread priority can be changed with VIDEO_THREAD_NICE_LEVEL.

Example for airframe file

Add to your firmware section: This example contains all possible configuration options, not all of them are mandatory!

<module name="video_thread">
  <define name="VIDEO_THREAD_NICE_LEVEL" value="5" />
</module>

Module configuration options

Define Options

• name: VIDEO_THREAD_NICE_LEVEL value: 5
  Description: Nice level for each separate video thread

Module functions

Init Functions

These initialization functions are called once on startup.

• video_thread_init()

Periodic Functions

These functions are called periodically at the specified frequency from the module periodic loop.

• video_thread_periodic()
  • Frequency in Hz: 1
  • Autorun: TRUE
    Periodic function automatically starts after init.
  • Start function: video_thread_start()
    Executed before the periodic function starts.
  • Stop function: video_thread_stop()
    Executed after the periodic function stops.

Files

Header Files

The following headers are automatically included in modules.h

• video_thread.h

Source Files

• modules/computer_vision/video_thread.c
• modules/computer_vision/cv.c
• modules/computer_vision/lib/vision/image.c
• modules/computer_vision/lib/v4l/v4l2.c
• modules/computer_vision/lib/encoding/jpeg.c
• modules/computer_vision/video_thread_nps.c
• modules/computer_vision/cv.c
• modules/computer_vision/lib/vision/image.c
• modules/computer_vision/lib/encoding/jpeg.c

Raw video_thread.xml file:

<!DOCTYPE module SYSTEM "module.dtd">

<module name="video_thread" dir="computer_vision">
  <doc>
    <description>
      Read video devices in a thread.
      Manager module which creates a video processing thread for each video device to be used. Only for Linux devices.
      To be used in other modules for further processing (e.g. opticflow, QR code, streaming). Using 'cv_add_to_device'
      from cv.h will register a processing function and initialize the video device if necessary. Thread priority can
      be changed with VIDEO_THREAD_NICE_LEVEL.
    </description>

    <define name="VIDEO_THREAD_NICE_LEVEL" value="5" description="Nice level for each separate video thread"/>
  </doc>

  <header>
    <file name="video_thread.h"/>
  </header>

  <init fun="video_thread_init()"/>
  <periodic fun="video_thread_periodic()" freq="1" start="video_thread_start()" stop="video_thread_stop()" autorun="TRUE"/>
  <makefile target="ap">

    <file name="video_thread.c"/>
    <file name="cv.c"/>

    <!-- Include the needed Computer Vision files -->
    <include name="modules/computer_vision"/>
    <file name="image.c" dir="modules/computer_vision/lib/vision"/>
    <file name="v4l2.c" dir="modules/computer_vision/lib/v4l"/>
    <file name="jpeg.c" dir="modules/computer_vision/lib/encoding"/>

    <!-- Random flags -->
    <!-- Does this influence the compilation of fast9? -->
    <define name="__USE_GNU"/>
    <flag name="LDFLAGS" value="lrt"/>
    <flag name="LDFLAGS" value="static-libgcc"/>
  </makefile>
  <makefile target="nps">
    <file name="video_thread_nps.c"/>
    <file name="cv.c"/>
    <include name="modules/computer_vision"/>
    <file name="image.c" dir="modules/computer_vision/lib/vision"/>
    <file name="jpeg.c" dir="modules/computer_vision/lib/encoding"/>
    <flag name="LDFLAGS" value="lpthread"/>
  </makefile>
</module>