QuickTime Streaming

Extra Information TLV Table Format

The Extra Information TLV table is present in a packet table entry if, and only if, the X bit is set in the flags field of that table entry. The Extra Information TLVs provide a way to extend the RTP hint sample format on a per-packet basis.

The Extra Information TLV table has a size field indicating the whole size of the table. Each entry in the table is a TLV, formatted like an atom, with a 4-character type field, a 64-bit size field, and a data field. The data field in a TLV is padded to a four-byte boundary. The size field indicates the whole size of the TLV, including its data, size, and type fields, and any padding.

Walk the TLV table as you would an atom structure, ignoring any TLVs whose type you do not recognize.

Table 5 Extra Information TLV table structure

Field	Bytes	Description
Table size	4	32-bit integer indicating the whole size of the table, including this field
TLV 1	variable	Each TLV has a 32-bit size field, a 4-character type field, and a variable-length data field. The data field is padded to a 4-byte boundary.
TLV 2	variable
...	variable
TLV n	variable

The only TLV currently defined is the RTP timestamp offset. This can be used for data types whose RTP timestamp does not monotonically increase. The definition of the RTP timestamp offset TLV follows.

Size: A 64-bit integer containing the size of the TLV in bytes. Size for this TLV is always 12.
Type: 'rtpo'
Data: A signed 32-bit integer which should be added to the RTP timestamp for this packet.