QuickTime Streaming

Passing Non-Media Data

Media packetizers and packet reassemblers are generally concerned with media sample data, such as video frames or audio samples. QuickTime movies commonly contain track-level information, such as a transformation matrix, or audio volume, that is applied to the sample data but is not embedded in it.

Packetizers and reassemblers can optionally support the passing of this type of data. If your packetizer supports passing of a particular type of information, such as audio volume or transformation matrix, it should indicate this in its public resource (as described in "The 'pcki' Public Resource" ).

In the course of normal operations, a media packetizer may receive a SetInfo command that specifies this type of information. A packetizer that can send a transformation matrix, for example, could receive such a call whenever the matrix changes.

It is up to the packetizer to package this information in a way that will be recognized by the reassembler and to send it along.

When a reassembler receives this type of information, it signals the fact by calling RTPRssmSendStreamHandlerChanged . It may then receive a series of GetInfo calls to determine what information it has. It passes the information in response to these calls, and QuickTime does the rest.