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instruction. The reference frame is panned, rotated and zoomed in accordance to GMC warp points to create a prediction of how the following frame will look. Since this operation works on individual pixels (rather than blocks), it is capable of creating predictions that are not possible using
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offers 1 warp-point GMC encoding: This enables easier hardware support in DivX certified and non-certified devices. But as 1 warp-point GMC limits the global transform to panning operation only (since panning can be described using blocks), this implementation rarely improves video quality.
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Because the transforms used in global motion compensation are only added to the encoding stream when used, they do not have a constant bitrate overhead. A predicted frame which uses GMC is called an S-frame (sprite frame) while a predicted frame encoded without GMC is called either a
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specification - designed as a successor to MPEG-4 ASP. Most of GMC's benefits could be obtained via better motion vector prediction. GMC also represents a large computational cost during encoding which yields relatively minor quality improvements.
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in such a frame can be compensated using global motion (no further motion information is then signalled) or, alternatively, local motion (as if GMC were off). This choice, while costing an additional
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Due to the extra decoding CPU cost of global motion compensation, most hardware players do not support global motion compensation.
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offers 3 warp-point GMC encoding: As a result, it currently has no hardware support.
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Lair Of The
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