iPhone can play MPEG-4 base video file(s). The typical container file extensions are MP4, MOV, and M4V.
There two video coding method in MPEG-4 as follows
MPEG4 ASP (or SP)
ASP (Advanced Simple Profile) is the updated version of SP(Simple Profile) but not big difference.
ASP can support B frames, QPel, GMC, and others.
If use this kind of advanced encoding option while transcoding, iPhone can not play correctly.
If use QPel, GMC option, iTunes will not allow to add the media file input sync windows.
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