Copyright: Copyright © 2000 Ligos Corp.


Quick Compressor
Quick Compress

Indeo® video’s normal offline encoding can be time-consuming.  The Quick Compress option allows Indeo video to encode video many times faster than it otherwise would.  Exactly how much faster depends on the specific content of the source video and the other encoder options you’ve selected.  However, this option uses a subset of the offline encoder’s compression techniques, speeding compression but slightly reducing overall visual quality.  Data rate control may also be slightly less accurate.

If you choose Quick Compress, three options are automatically disabled: transparency, access key and viewport size (local decode), but the scalability option remains enabled.

Use Quick Compress to test, prototype, or preview the appearance of your video after encoding with Indeo video. It is also suitable for hard disk applications in which data rate control is less critical.  However, after you’ve previewed the video and made any required adjustments, we recommend using the off-line encoder for your final product.  For the best quality at lower data rates, or to achieve a steady data rate without spikes, do not use the Quick Compressor.

The Indeo video codec can play any video clip compressed with the Quick Compressor.

To enable quick compression, select the Quick Compress box in the Encoder Controls area.


Scalability

When scalability is enabled, Indeo video compresses video in a manner that allows playback visual quality to vary automatically, based on the available processing power of the playback system.  If processing power is inadequate, the codec degrades visual quality incrementally rather than dropping frames.  This avoids jerky video playback.

To enable scalability, check the Scalability box in the Encoder Controls area.


Transparency

The Indeo video codec supports a form of transparency analogous to chroma-keying or blue-screening, allowing you to composite foreground objects over backgrounds from a source other than the same video clip.  This transparency encoding is flexible, allowing for multiple foreground objects of complex shapes.  Foreground objects can also move from frame to frame, allowing you to create what one might call video sprites.

The encoder box offers three choices for handling transparency: first-frame analysis, alpha channel, or none.

First-frame analysis:
The first frame of the video is analyzed to determine the color or range of colors that represent the transparent background, such as the blue screen.  If you choose this method, the first frame of your video must be a carefully lit shot of nothing but the background that you intend to become transparent.

Alpha channel:
The codec interprets the upper eight bits of the source video’s 32-bit RGB color space as an 8-bit alpha channel describing the transparency or translucency of each pixel in the frame.  Indeo video uses the alpha channel to generate a 1-bit transparency bitmask for each frame: a pixel is either transparent or not.  Translucency is not supported.

None:
This option disables transparency.

If either method of transparency is enabled, Indeo video analyzes each frame, separates the background pixels from the foreground pixels, and encodes only the foreground objects.

This option is disabled when using quick compression.


Access Key

If you are concerned about the illegal distribution of your copyrighted material, use Indeo video’s access key feature to prevent misuse of your video clips.  Access keys are numeric passwords that you insert into a video clip during compression.  A clip encoded with an access key can be played only by an application that has the correct key.  Media Player, for example, cannot play clips encoded with an access key because it cannot supply an access key to Indeo video.

To use this feature:

1. Check the Enable box in the Access Key field.  The compression application displays the Value field.

2. Enter a number between 0 and 4,294,967,295 in the Value field.  (Do not type commas.)

This value becomes the access key that an application must supply to play the video clip.

This option is disabled when using quick compression.


Viewport Size

Sometimes an application needs to display only part of a video image.  In such a case, it’s efficient to avoid wasting system resources decoding the part of the source image that does not need to be displayed.  Indeo video provides this capability with local decode.  The playback application can tell Indeo video to decode only a rectangular subregion of the source video image: the viewport.

If you plan to make use of this feature, you must specify the minimum possible size of the local decode viewport when you compress the clip.  Then the display size of the viewport can be enlarged dynamically during playback.  Its location can be changed dynamically during playback as well.

To enable the local decode feature during video playback, select one of the viewport sizes in the drop down list.  The available sizes are: 64x64, 128x128 and 256x256.  The dimensions are in pixels.

To disable local decode for a given video clip, select “Full image” in the drop down list.

This option is disabled when using quick compression.


Load Defaults

By default, Indeo video saves encoder options between uses.  If you would like to reset the option to the default options, click the Load Default button.

The defaults are:

Quick compression off.

Scalability off.

Transparency set to None.

Access key disabled.

Viewport size set to “Full Image”.


Other Tips

Audio Interleave

During playback, if too many frames are being dropped, or if the audio seems poorly synchronized with the video, ensure that the audio interleave is set to 1 frame.


Customer Support

Technical support on Indeo can be obtained through the following:

Ligos Support:	http://www.ligos.com/indeo/support.shtm

Email:                    indeo@ligos.com


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Copyright Notice

Indeo ® video Copyright 2000 by Ligos Corp.


Related Topic

These windows display information about related topics.


pop-up definition

These boxes pop up on your screen and define terms or provide small pieces of information.  Click anywhere on your screen to close a pop-up box.


to encode

This is the process Indeo video employs to convert video from its color format (RGB, YVU etc.) to the IV50 compressed format.


interframe encoding
interframe compressing

This is a form of compression in which the codec compresses data in one frame relative to the data in others, creating delta frames.


to decode

This is the process of decompressing video and then converting to a color format (RGB, YVU, CLUT 8, YUY2, CLPL etc.).


pixel

This is a picture element; the smallest independently accessible unit of a digital image; a dot containing color and brightness.


audio interleave

This is the granularity with which the audio data alternates with the image data in a video file.


interframe compressing

This is a form of compression in which the codec compresses the data in one frame relative to the data in other frames, creating delta frames.  “Intraframe compressing” refers to compression in which the data in one frame is compressed only relative to itself, resulting in key frames.