Dynamic Display - Generating AVIs

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Dynamic Display - Generating AVIs

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PipeLay allows you to create Windows® standard video files (AVI's) from PipeLay animations. Particular advantages of AVI files are that:

They can be shared with non-PipeLay users.

The are easy to include in presentations.

AVI Properties

Invoking the Generate AVI… option on the Animate menu opens the AVI Properties dialog shown below. This is where you will specify the settings for your AVI file. As you can see, the inputs are divided into three sections, Properties, Start/Finish Time and Viewpoint, each of which is now discussed in more detail.

display_avi_properties

Properties

In this section you may choose the AVI’s frame rate. The default frame rate of 10 frames per second will usually be sufficient for depicting PipeLay animations smoothly. The size of the AVI animation will always be the same as the first animation window. To produce smaller/larger AVI animations, resize the animation window to the required extents before generating the AVI.

Start/Finish Time

You might well only want a portion of the PipeLay analysis written to the AVI file. Perhaps you want to exclude the ramp time or initial transients, or simply focus on the response in a particular period. This section allows you to specify the start and end times (in simulation time) for the animation.

Viewpoint

Sometimes, you will want to be able to present your model from more than one angle in your AVI file. The variable viewpoint facility allows this.

The viewpoint from the first animation window provides the default AVI viewpoint. To specify a moving viewpoint, simply click on the drop-down list and select Dynamic.

display_viewpoint

The area below then becomes active. It is shown below with a number of viewpoints added at various times.

display_viewpoint_dynamic

To add a viewpoint at a particular time, simply fill the time and axis rotations in the boxes provided and press the Add button. The rotations are about the screen X, Y and Z axes. Viewpoints added incorrectly may be simply removed by selecting them in the list and pressing the Remove button. The Clear All button will remove all viewpoints entered.

The software moves smoothly between the viewpoints, interpolating to find its position at intermediate times.

 

Creating the AVI

Once you have specified all the AVI properties, simply press the OK button to proceed.  The software can take anywhere from a few seconds to a couple of minutes to render the AVI file in memory. Processing progress is shown via the progress bar.

Once processing is completed, you are prompted to choose a location to save the AVI file to disk, as shown below. Press OK to confirm.

avi_save_as

Finally, you are asked to choose a video compression or codec, as shown below.

avi_compression

A detailed discussion of codecs may be found in the next section, but for now, simply choose Full Frames (Uncompressed) which means that you are not specifying a codec, and press OK.

 

Codecs

“Codec” is short for “coder/decoder”. Codecs represent different video formats and compress video files to reduce their size. Usually, higher compression implies lower quality video.

Requesting uncompressed video produces an AVI file of the highest quality, the animation looks exactly as it would in the Dynamic Display itself. However these files tend to be very large indeed and unsuitable for applications where size is a concern, such as emailing.

The exact list of codecs available varies from machine to machine and you may like to experiment to find out which codec provides a satisfactory trade off between quality and file size. The “Microsoft Video 1” codec, for example, can compress PipeLay animations by about 20 times while retaining reasonable video quality.

Bear in mind that whichever codec you choose, the recipient of your AVI file will also need the same one installed on their machine.  Thankfully, this is often not a great concern as many modern video playing packages, such as the Windows® Media Player, will automatically download and install codecs on-demand.