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 Add a special MP4 marker to allow playback on vintage iPod 5th Generation devices circa 2006. Other settings may affect compatibility. 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