RTP Payload Format for Real-Time Pointers M. Reha Civanlar AT&T Labs - Research 45 th IETF Oslo, Norway

7/14/99 45 th IETF - Oslo, Norway 2 Why do we need this? In presentations, it is essential to transmit viewgraphs & real-time pointers A straightforward approach, using a video codec, is not feasible because: –Viewgraphs require high spatial resolution –Pointer requires high temporal resolution

7/14/99 45 th IETF - Oslo, Norway 3 Capturing the pointer, e.g. Network Interface Video Capture VGA Interface Mouse Interface PC, Workstation Document Camera Mouse (Pointer) Display Pointer Projector Network Baseband Video

7/14/99 45 th IETF - Oslo, Norway 4 Payload format draft-civanlar-pointer |V=2|P|X| CC |M| PT | sequence number | | timestamp | | synchronization source (SSRC) identifier | : contributing source (CSRC) identifiers : +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ |L| | x coordinate |R| | y coordinate | MBZ MBZ

7/14/99 45 th IETF - Oslo, Norway 5 Payload format Payload: –The pointer's x and y coordinates are measured from the upper left corner of the associated display window in pixels. The associated window SHOULD be specified out-of-band. The coordinates are represented as 14 bit, unsigned integers. –When the M bit is set to one, L (left) and/or R (right) bits are set to one if their respective mouse buttons are down at the sampling time. RTP Header Usage: –Marker (M) bit: Set to one if the payload carries information about mouse buttons. –Timestamp: The sampling time for the pointer location measured by a 1KHz clock.

7/14/99 45 th IETF - Oslo, Norway 6 Issues: More buttons –how many? Represent pointer position as a fraction from 0 to 1 in both x and y directions. –resolution? –computational overhead Loss resilience?

7/14/99 45 th IETF - Oslo, Norway 7 Issues Should this be a workgroup item? Should we extend this to generic mouse coordinate transport?