Different MPEG coding strategies
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Strategy			Speed	Compression	Quality
--------			-----	-----------	-------
Increase MV Search Range	Down	Up		Up?
Increasing Q-Scale		Same	Up		Down
Decreasing Q-Scale		Same	Down		Up
Use half-pixel search		Down	Up		Up?
Use pixel subsampling		Up	Down		Down?
Use motion vector subsampling	Up	Down		Down?
Use decoded frame as reference	Same	Unknown		Up?
Varying q-scale			Down	Up		Down