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TANDBERG
FieldView Administrator Guide
D14098.02 June 2008
About Media Configuration
When a call is started, the setting specified in the TANDBERG FieldView
Application under Preferences > CallWindow > Video > Configuration
determines the initial media configuration used for the call (see section
Call
Window
). If the configuration is set to Use Current FD Settings, then the
Stream Setup on the TANDBERG FieldView Device is used.
After the call is established, users can select an alternate media configuration
from either end without ending the call. The video and subject audio streams
will be briefly stopped and then restarted at the new rates and settings. At the
TANDBERG FieldView Application this selection is done using the Audio/Video
Setting call control. At the TANDBERG FieldView Device it is done using the
Stream Setup options (see Fig. 6-2).
If a recording is played back in a call, it will use the media configuration
parameters of the recording. Note that the frames per second reported by the
TANDBERG FieldView Application when playing back is based upon the average
frame rate for the entire recording, taking into account frames missed due to
packet loss. This generally results in a lower reported frame rate than the rate
used in the original recording.
Note that when the
Still Image Capture
button on the TANDBERG FieldView
Device is pressed, the video stream is not stopped even though the image
appears frozen. Stopping the video stream is controlled by the green
Streaming on/off
button. Also note that when image sharing, the video
stream can be configured to continue, pause or stop depending on user
preference and the need to control bandwidth usage.
Understanding the Media Configuration
Parameters
When operating under conditions such as limited available bandwidth or in the
presence of packet loss, achieving the best video image requires adjusting the
media parameters to achieve the best possible image. This section describes
the media configuration parameters and how they can be used to achieve the
best video.
Device Type
Media configurations are defined separately for NTSC and PAL TANDBERG
FieldView Devices since the specific configuration choices offered vary
depending on the differences between NTSC/PAL standards. Incompatible
media configurations are hidden from the user.
Note that the built-in High/Medium/Low media configurations auto adjust for
NTSC/PAL differences according to table 6-1.
Bit Rate
When streaming video, the TANDBERG FieldView Device continuously encodes
the images into a MPEG-4 bit stream which, on average, is at the Target Bit
Rate and is limited to the Peak Bit Rate. The bit rates you should specify are
generally governed by the amount of bandwidth available over the network
path between the TANDBERG FieldView Device and TANDBERG FieldView
Application. Since a path is generally made of several segments, it is the
Chapter 6
