This answer really depends on the Main Video resolution and Frame rate you are setting the TX9xxx to for the CUCM Device profile "Product Specific Configuration Layout" for the : Quality (per Display) as well as Main Display Frames Per Second and Bandwidth Allocation Weights all play into this factor.
Please refer to the following link for more information on this issue:
http://www.cisco.com/en/US/docs/telepresence/tx_sw/6_0/admin/guide/tx_sw_admin.pdf
Understanding How Endpoints Determine fps and Video Quality
During Cisco TelePresence call setup, the sending and receiving endpoints determine the fps (30 or 60
fps) and video quality (1080p or 720p) in which the video streams are sent and received.
The determination is made as a result of the following factors:
•
The amount of Transport Independent Application
Specific (TIAS) bandwidth that is negotiated
between the sending and receiving endpoints.
The minimum amount of bandwidth is determined
by the settings of Main Display Frames Per
Second and Quality (Per Disp
lay) in the Phone Configuration page of Unified CM.
Table 4-3
displays the bandwidth requirements based on the Unified CM configuration.
•
The maximum frame size that the network and system can accommodate.
•
The negotiation of the video resolution and frame
rate (in fps) by the sending and receiving
endpoints.
•
The maximum bit rate allowed in the Region settings
for your device in Unified CM. These settings
are applied to the Device Pool, which
in turn are applied to your device.
To find your region settings, log in to the Cisc
o Unified CM Administration GUI and navigate to
System > Region
. The maximum rate is the value shown in the Max Video Call Bit Rate (Includes
Audio) field.
Table 4-2
shows the three criteria that
are required in the first three columns of the table, and the
resulting video stream that can be sent
in the fourth column of the table.
If any of the factors do not meet the minimum requirements, the system attempts to send and receive
video at the next lowest rate as shown in
Table 4-4
.
For example, if the system and network cannot meet
the minimum requirements to send a video stream
with the maximum video quality of 1080p 60, the sy
stem attempts to negotiate a video stream of
720p 60. If the system cannot meet the requirements to send a video stream of 720p 60, it attempts to
negotiate a video stream of 720p 30as shown in
Ta bl e 4 -4
.
Under the following circumstances, the 60 fps-capable Cisco TelePresence endpoints and device send
the main video stream at 30 fps:
•
When in a call with an endpoint or device that supports a maximum frame rate of 30 fps.
•
When in a call with a Cisco TelePresence endpoint that is registered with a Cisco Unified
Communications Manager (Unified CM) version that does not support 60 fps as a setting for Main
Display Frames Per Second in the Phone Configuration page.
•
When in a call with a Cisco TelePresence endpoint that is registered with a Unified CM version that
supports 60 fps but “30 fps main” is the setting for Main Display Frames Per Second in the Phone
Configuration page
