IPi Recorder User's Guide

Common

iPi Recorder serves three main activities: video recording, video playback, and video conversion. To switch between these activities, three big labels at the top are used. Label of current activity is displayed in larger font size, and is underlined.

Menu tools at the top-right contains several auxiliary functions.

On-Screen Controls

Everewhere in the program when you see some screen displaying image from camera, whether in Recorder or Player, placing the mouse pointer over that screen brings it's on-screen controls. These controls provide basic functions for changing the display mode for this screen:

• Mirror image (flip horizontal)

  This may be especially useful for front-facing cameras during recording.

• For depth + color videos you can set the layout of two images
• Enter full screen mode

  In full screen mode, only 1 camera screen is displayed at once. You can switch between cameras using corresponding buttons or PageUp/PageDown keys. To exit full screen mode, pull off the full screen switch or press Esc key.

On-screen controls window can embed additional controls specific for the situation where screen is displayed.

On-screen controls

Full screen mode

Recorder

Recording process is organized in several sequential stages.

Cameras

This is initial stage of recording. You are presented with the list of cameras/depth sensors available on your system and supported by iPi Recorder.

Select (by clicking) the cameras you wish to use and press the SETUP button to continue. Selected cameras are highlighted with orange background. Program remembers your selection: next time you start iPi Recorder you don't have to bother with selection again, unless you've replugged cameras.

To refresh the camera list — for example, when you've just attached new camera — press the REFRESH button. The list refreshes automatically each time you're entering this stage. When new camera is detected, it is selected automatically.

In expander camera types support to the right you can find information how to enable support for different devices similar to that presented in the installation instructions.

Setup

Setup stage allows to adjust general and individual camera settings before recording. You can:

• Select working video mode
• Adjust number of cameras displayed in a row to optimize screen space usage
• Reorder cameras.

  To place camera to the specific position, drag it's screen to this position. You can also throw away unneeded camera if it was selected by mistake, simply by dragging away it's screen.

  Tip. For color cameras, it is recommended to place cameras in Recorder in the same order they go around capture area —either clockwise, or counter-clockwise. This will make calibration process in iPi Mocap Studio much simpler.

• Set global properties for all cameras, if there are any.

  Example of such property is darkening for calibration for PS Eyes.

• Set properties of individual cameras.

  Examples of such properties include brightness and contrast for color cameras, and elevation angle for Kinects.

  To access individual camera properties, press the PROPERTIES button in the camera's on-screen controls.

All settings applied on this stage cannot be modified on the following stages. Program remembers settings values and restores them on the next run automatically.

Note. Display settings you are making in the camera's on-screen controls do not affect the recorded video. For example, if you turn on mirroring, then image in video still will be unflipped, and if in depth + color mode you change the layout to display only depth, still both depth and color images will be present in video.

Selecting video mode	Reordering cameras
Camera properties

Background

Before you start to record any videos, you'll need to evaluate scene's background. Background is the picture of only static (not moving) objects in the capture ara. Evaluated background is embedded inside videos and is later used to easily detect moving objects. Also, background is employed for compressing videos with the background subtraction method.

Usually background should be evaluated only once during a recording session. However, any time the environment gets significant changes, you need to reevaluate background. Examples of such changes include changing lighting conditions, introducing new or moving existing static objects within the cameras' field of view. Also, you will need to reevaluate background each time after you went back to Setup or Cameras stage, because changing the settings invalidates currently evaluated background.

Before starting evaluation, you can set its duration. In general, the longer duration, the better evaluated background. Though, default duration of 5 seconds is sufficient for the most situations. Less values can be set for testing purposes, when you frequently pass through Setup stage, trying out different settings.

Often there is situation when computer with iPi Recorder is located in some camera's field of view. So to evaluate background, you need to go away from computer, but being away, you cannot start the evaluation process. In that case, you can set delay for evaluation to start, so after pressing the EVALUATE button, you have enough time to leave capture area. After you've started delayed evaluation, count delay + duration seconds, and then you can safely return to computer.

After backgound is evaluated, you can proceed to Record stage.

Background is not evaluated yet	Counting down for delayed start
Background is already evaluated

Record

The most interesting part — recording a video. In short: select destination file, set compression options and hit START button to begin recording. When action is over, just press STOP button — and you have your video file.

When selecting destination file, you can use special <time stamp> placeholder anywhere in the file name. It allows to easily make unique file names: it is replaced by current date and time on recording start. CHANGE FOLDER button shows up folder selection dialog, leaving entered file name without changes.

Different compression options allow to balance load of CPU and storage (both space and writing speed) corresponding to a system's performance. With depth sensors, compression options are set individually for depth and color images. The following methods are available:

• None

  Uncompressed data. The lowest load of CPU, and the highest load of storage.

• Background subtraction

  Lossless computational-inexpensive compression. Gives compression ratio approximately in range 2..10. Some trade-off between CPU and storage.

• JPEG (only for color)

  Lossy computational-expensive compression. Gives compression ratio up to 100 and more, depending on setting the quality value. The highest load of CPU, and the lowest load of storage.

  Note. Use with caution for color cameras. Lossy compression reduces quality of the image, and may lead to more tracking errors. If you are forced to use it due to limited disk space/speed, leave the quality value at considerably high level.

As with evaluating background, you can set delayed start of recording, so you have time to get off the PC and make your favorite pose before an action begins.

During recording, some statistics are displayed, such as current file size, disk throughput, write buffer usage. Also you can expand camera statistics to watch for frame drops and related stuff. All those values may help you to discover performance issues. For example overflow of the write buffer signals that you have low disk speed — you can try to use more compression. Frame drops (if they appear only during recording) may indicate that your CPU is overloaded and you need to switch to less agressive compression options.

After recording, the new video file is placed at the top of the recent records list (it is expanded automatically on recording stop). In one click you can open the video in player.

Camera statistics