ISO Base Media File Format
ISO Base Media File Format (sometimes abbreviated BMFF or ISO BMFF) is a metaformat for "time-based" media formats (mainly audio and video). It is based on the more-general metaformat we're calling boxes/atoms format.
Files (almost) always have an "
ftyp" box, containing a list of "brands" that give information about the specific file format. See the boxes/atoms article for more about brands.
Much of the format was copied from QuickTime format.
There appears to be no simple way to distinguish BMFF from other formats.
A file in boxes/atoms format that has both an "
ftyp" box and an "
moov" box probably uses a BMFF-based format. However, for compatibility with certain older files, the "
ftyp" box can sometimes be omitted if the brand would be "
A BMFF file may (or may not) be labeled with one or more of the generic BMFF brands: "
isom", and "
Note that some formats use an "
ftyp" box, without being conformant with BMFF (though they may borrow elements from it). An example is JP2.