Video Stabilizer Demo App

Video Stabilizer Demo user guide.

Introduction

nvx_demo_video_stabilizer is a demo that demonstrates the image based video stabilization algorithm. It uses the Harris feature detector and sparse pyramidal optical flow method (Lucas-Kanade) to estimate a frame's motion.

The demo uses the following pipeline:

                                (next frame)
                                      |
+-------------------------------------+-------------------------------+-------+
|                                     |                               |       |
|                              [ColorConvert]                         |       |
|                                     |                               |       |
|    +--------------------------------+                               |       |
|    |                                |                               |       |
|    |                        [GaussianPyramid]                       |       |
|    |                                |                               |       |
|    |         (pyr delay -1)   (pyr delay 0)      (pts delay -1)     |       |
|    |               |                |                  |            |       |
|    |               |                |                  +----+       |       |
|    |               |                |                  |    |       |       |
|    |               +----------------+------------------+    |       |       |
|    |                                |                       |       |       |
|    |                         [OpticalFlowPyrLK]             |       |       |
|    |                                |                       |       |       |
|    +-------+------------------------+                       |       |       |
|            |                        |                       |       |       |
|      [HarrisTrack]                  +-------+---------------+       |       |
|            |                                |                       |       |
|      (pts delay 0)                  [FindHomography]                |       |
|                                             |                       |       |
|                                     +-------+-----------------------+       |
|                                     |                                       |
|                            [HomographyFilter]                               |
|                                     |                                       |
|   (...)   (matrix delay -1)   (matrix delay 0)                               |
|    |             |                  |                                       |
|    +-------------+------------------+                                  [ImageCopy]
|                  |                                                          |
|          [MatrixSmoother]                  (RGBX delay -n)   (...)   (RGBX delay 0)
|                  |                               |
+------------------+                               |
                   |                               |
        [TruncateStabTransform]                    |
                   |                               |
                   +---------------+---------------+
                                   |
                           [WarpPerspective]
                                   |
                             (stabilized)

nvx_demo_video_stabilizer is installed in the following directory:

/usr/share/visionworks/sources/demos/video_stabilizer

For the steps to build sample applications, see the Samples and Demos section for your OS.

Executing the Video Stabilizer Demo

./nvx_demo_video_stabilizer [options]

Command Line Options

-s, --source

• Parameter: [Input URI]
• Description: Specifies the input URI. Accepted parameters include a video (.avi), an image sequence (.png, .jpg, .jpeg, .bmp, .tiff) or camera to grab frames.
• Usage:
  • ./nvx_demo_video_stabilizer --source=/path/to/video.avi for video
  • ./nvx_demo_video_stabilizer --source=/path/to/image_%04d_sequence for image sequence
  • ./nvx_demo_video_stabilizer --source=device://camera0 for the first camera
  • ./nvx_demo_video_stabilizer --source=device://camera1 for the second camera.

-n

• Parameter: [Number of smoothing frames]
• Description: Specifies the number of smoothing frames, should be in the range [1,6] (5 by default). Frames for smoothing are taken from the interval [-numOfSmoothingFrames; numOfSmoothingFrames] in the current frame's vicinity.
• Usage:
  ./nvx_demo_video_stabilizer --source=video.avi -n6

--crop

• Parameter: [Crop margin for stabilized frames]
• Description: Specifies a proportion of the width (height) of the frame that is allowed to be cropped for stabilization of the frames. The value should be less than 0.5. If it is negative then the cropping procedure is turned off.
• Usage:
  ./nvx_demo_video_stabilizer --source=video.avi --crop=0.1

-h, --help

• Description: Prints the help message.

Operational Key

• Use ESC to close the demo.
• Use Space to pause/resume the demo.