NSIsNotNil HBContainerTransformer Optimize MP4 for progressive download. After encoding, data is reorganized and rewritten to allow immediate playback over a network, without needing to download the entire file. NSIsNotNil NSNegateBoolean Aligns the initial timestamps of all audio and video streams by inserting blank frames or dropping frames. May improve audio/video sync for broken players that do not honor MP4 edit lists. NSIsNotNil NSNegateBoolean Add a special MP4 marker to allow playback on vintage iPod 5th Generation devices circa 2006. Other settings may affect compatibility. NSIsNotNil NSNegateBoolean NSNegateBoolean