change output method

write mdat box and size in the end of meta_data block.
Revert "add mp4atom.h"

This reverts commit dc1e4cd4ae0ea247b623a80be994ebc8e007095f.
Revert "Revert "add mp4atom.h""

This reverts commit 761b156dce5c9c88a4cf52fc6825b8658c574a3e.