This section documents various codes used in the file format; handler codes (that declare track types) and group types (as used in the AVC specification) in particular.
Code Abstract Type Defined in/by
3gag Text track3GPP PSS Annex G video buffer parameters group 3GPP
3gsd 3GPP Scene Description handler 3GPP
ID32 ID3 version 2 meta-data handler (meta box) handler inline
avcb AVC HRD parameters group 3GPP
avll AVC layer description group group AVC
avss AVC Sub-sequence group group AVC
crsm ClockReferenceStream handler MPEG-4
fdsm Font data streams (defined in part MPEG-4 part 18) handler MPEG-4
gesm General MPEG-4 systems streams (without specific handler) handler see (1) below
hint Hint track handler ISO
ipsm IPMP Stream handler MPEG-4
meta Meta-data streams handler MPEG-4
m7sm MPEG7Stream handler MPEG-4
mjsm MPEG-J Stream handler MPEG-4
mp21 MPEG-21 Digital item handler MPEG-21
ocsm ObjectContentInfoStream handler MPEG-4
odkm OMA DRM KMS protection scheme protection scheme type OMA DRM 2.0
odsm ObjectDescriptorStream handler MPEG-4
roll Pre/Post roll group group AVC, ISO
sdsm SceneDescriptionStream handler MPEG-4
soun Audio track handler ISO
text Text track handler 3GPP
vide Video track handler ISO
  1. There only exists a defined set of handler code-points in MP4 file format allowing declaration of most known MPEG-4 Systems streams. However there is no provision for private MPEG-4 streams, which may be used by the file creator. This will likely push the file creator into using one of the defined handler types, which is wrong and may corrupt processing by some file readers. This is a generic handler type to indicate that the media is an MPEG-4 systems stream, without further details on the stream type itself. The associated sample descriptions must still remain the same, i.e. "mp4s" as used with all MPEG-4 systems streams.