Content overview

General information on Screengrabbing

Processor load very high during Screengrabbing

Adaptive Framerate option

Quick Capture Mode

Recording video windows by Screengrabbing

Panning during Screengrabbing recordings

Question:

What should generally be considered for the use of Screengrabbing?

Solution:

For a successful recording of Screengrabbing clips the following points should be noted:

• Capacity: Please take care that the system does not work at full capacity (see Processor load very high),
• Screengrabbing Codec: For best results, use the special Screengrabbing Codec LSGC (LECTURNITY Screengrabbing Codec) provided with LECTURNITY. This codec is lossless and very performant for Screengrabbing,
• Consistent background: For best results and smallest clip files please take care that you use a consistent (single-colored) desktop background.

Figure 1: Adequate desktop background for Screengrabbing

Figure 2: Inadequate desktop background for Screengrabbing, as it is not consistent

Question:

During a Screengrabbing recording the processor load is very high, other applications are very unresponsive. Screengrabbing is quite resource-intensive; therefore the CPU load can be very high in some situations. 

Solution:

There are various possibilities of reducing the processor load during a Screengrabbing recording.

Possibility 1: Reduce the framerate with which you make the Screengrabbing recordings. You have two possibilities:

• Static framerate: Set a low, static (fixed) framerate.
• Adaptive framerate: Use the option "Adaptive Framerate". In the project settings you can select with which resolution which framerate is to be used. See also Adaptive framerate option.

Figure 3: Screengrabbing - Framerate settings

Please note that a framerate higher than 10 is not appropriate in most cases.

Possibility 2: If you work under Windows 2000 or XP, then you can deactivate the hardware acceleration of your graphics adapter. A deactivation of the hardware acceleration will result in a faster access to the graphics data, since the data is not kept in the graphics adapter's memory but in the main memory. In the LECTURNITY Assistant you can specify that the hardware acceleration is to be turned off automatically (see figure).

At the beginning of a LECTURNITY recording, the hardware acceleration will be turned off if this option is activated, this results in a short flickering of the screen. This flickering also occurs at the end of a recording when the hardware acceleration is turned on again.

Possibility 3: Activate the Quick Capture mode (see figure 4). In this mode less screen data is read out and thus the processor load is kept at a lower level.

Figure 4: Screengrabbing - Handling Settings

Question:

How does the adaptive framerate work?

Solution:

The "adaptive framerate" helps you to define an appropriate framerate for your system depending on the size of each clip. The setting "10 frames with a resolution of 320×240 pixels" means the following: if you select a region of 320×240=76800 pixels, then the framerate 10 will be set for the recording. Larger regions get respectively lower framerates and vice versa. A selection of 640×480=307200 pixels would be recorded with a framerate of 2.5 frames per second. This procedure makes sure that the processor usage does not exceed a certain limit.

Hint:

You should try different framerates to determin which one ist best suited for your system and/or needs.

Even when you determine that in case of a region of 640×480 pixels, 10 frames per second are to be recorded, smaller regions will never be recorded with a higher framerate than 10. For Screengrabbing clips, 10 frames per second is a reasonable upper limit. Higher framerates only increase the data rate without an improvement of perceived quality.

Question:

How does the "Quick Capture" mode work? Which impact does it have on my Screengrabbing recordings?

Solution:

The "Quick Capture" mode makes higher framerates during Screengrabbing possible and thus mouse movements are more fluent in the clip. This is achieved by reading a complete image from the screen only once per second; the other temporary images contain the latest mouse pointer as the only change in case it has moved. By this prodedure, the processor is relieved from frequent data accesses and thus higher framerates are possible, with fluent mouse movements at the same time.

The disadvantage of the Quick Capture mode is that not every change on the screen appears on the Screengrabbing clip directly, but up to one second later. Usually, this is hardly noticeable and the Quick Capture mode produces similarly good results as the normal mode, with the difference that the processor load is lower.

Question:

Screengrabbing recordings that record a video window only display a black rectangle instead of a video. The video window is displayed by the Windows graphics adapter hardware acceleration. Therefore, LECTURNITY cannot grab the screen data directly.

Solution:

Turn off the hardware acceleration for the Screengrabbing temporarily. LECTURNITY can automatically do it for you. See Processor load very high during Screengrabbing on how to configure this.

Question:

How can I change the area which is currently recorded during Screengrabbing? I.e., how does "panning" work with the LECTURNITY Assistant?

Solution:

Two possibilities exist how to change the screen area:

• By dragging the orange corners,
• By clicking the (left) "Ctrl" key and the (left) "Shift key and moving the mouse at the same time.

Please beware that the size of the region can not be changed during a recording. The reason is that each Screengrabbing clip is recorded in the AVI format which cannot handle different video image sizes in one single file.