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Chapter 10 - Conference Templates – Full Parameters View
10-28
Annexes - P, N and
F
Annexes are additions to the Video Format when
using H.263 Video Protocol and increases the
quality of the video display.
Annexes N, P and F are enabled only when you are
in Video Switching mode and the Video Protocol is
set to H.263. The Video Format may be set to QCIF,
CIF, 4CIF, 16CIF, VGA, SVGA, XGA, or NTSC.
When Video Format is set to Auto, the system
selects the appropriate annexes according to the
endpoint's capabilities. The annexes are required in
the Dual Stream mode, but may also be selected
independently.
• Annex F - Advanced Prediction Mode. This
annex enables the transmitting encoder to use
four motion vectors for every macro block (one
motion vector per block). A macro block is a
piece of the picture that contains four blocks.
Without this annex, the transmitting encoder can
only choose one motion vector for optimal
prediction of the macro block.
• Annex N - Reference Picture Selection Mode.
This annex enables the conference to recover
efficiently after transmission errors have
occurred in the macro blocks, and reported via a
relevant message to the speaker encoder.
• Annex P - Reference Picture Re-sampling. This
annex enables the transmitting encoder to apply
a re-sampling process to the previous decoded
reference picture in order to generate a warped
picture, for use in predicting the current picture.
The main purpose of this annex is to support the
relationship of the current picture to a previous
picture, which had a different source format,
such as CIF, QCIF, 4CIF, etc.
Table 10-3: Basic Conference Parameters
Option Description