89
the endpoint. The IP VCR chooses an audio codec
from those available, and sends audio data to the
endpoint in that format.
Audio codecs
to IP VCR
Which audio codecs the IP VCR advertises to
remote endpoints, restricting the endpoints' choice
of channels available for sending audio data to the
IP VCR.
Video codecs
from IP VCR
Restricts the IP VCR's choice of video codecs to be
used for receiving video from the endpoints.
When communicating with an endpoint, the IP
VCR receives a list of supported video codecs from
the endpoint. The IP VCR chooses a video codec
from those available, and sends video data to the
endpoint in that format.
Video codecs
to IP VCR
Which video codecs the IP VCR advertises to
remote endpoints, restricting the endpoints' choice
of channels available for sending video data to the
IP VCR.
Video
transmit size
optimization
Allows the IP VCR to vary the resolution and codec
of the video being sent to a remote endpoint within
the video channel established to that endpoint. The
options are:
• None: Do not allow video size to be
changed during transmission
• Dynamic resolution only: Allow video size to
be optimized during transmission
• Dynamic codec and resolution: Allow video
size to be optimized during transmission
and/or dynamic codec selection
With this option enabled, the IP VCR can, for
instance, decide to send CIF video within a 4CIF
channel if this will increase the viewed video
quality.
The circumstances under which decreasing the
video resolution can improve the video quality
include:
• if the original size of the viewed video is
smaller than the outgoing channel
• if the remote endpoint has used flow
control commands to reduce the
bandwidth of the IP VCR video
transmission
Typically, lowering the resolution means that the
IP VCR can transmit video at a higher frame-rate.
Video
resolution
selection
mode
This setting can be used to influence the choice of
outgoing video resolution made by the IP VCR in
certain circumstances.
• Default
The IP VCR will use its normal internal
algorithms to dynamically decide which
resolution to send in order to maximize
the received video quality.
• Favor 448p
The IP VCR will heavily favor sending
448p or w448p video (resolutions of 576
x 448 and 768 x 448 pixels respectively)
to those endpoints that are known to work
You should leave this at Default unless your
environment dictates 448p or w448p resolutions
only.