ABSTRACT
This publication
describes a means to adjust media parameters of active media streams in order
to:
·
assure that
resources are assigned to the highest priority calls
·
assure that
media parameters match user’s requirements based on their use cases
·
adjust media
parameters rather than shutting streams off completely
The solution
described uses weighted media parameter
requirements for making media parameter adjustment tradeoffs for existing media
streams.
PROBLEM
In real-time
streaming communications such as audio and video, there are multiple parameters
that can be changed that each contribute to the overall perceived quality of a
media stream. Some examples for video
are the frame rate, the resolution, and the delay. Example parameters for audio include the
sample rate and the delay.
In QoS control
systems it is desirable to be able to adjust the resource usage by various
streams in the network in order to assure that resources are assigned to the
highest priority calls. Most QoS control
mechanisms utilize preemption (shutting off a media stream) in order to free up
resources for other higher priority streams.
In some cases it is more desirable to adjust the media parameters
described above in order to free up resources and allow the stream to continue
rather than shutting it off completely.
SOLUTION
Individual media parameter settings contribute to the
overall perceived quality of a media stream.
Adjusting these parameters can trade-off aspects of media quality versus
resource usage. As an example,
adjustable media parameters for a video stream can include:
• Target bit
rate
• Resolution
• Frame rate
• Quality
• Delay
When a media stream is setup, the application can
assign a set of required and desired media parameter values and a set of
weightings to these various media parameters based on the requirements of the
user at the time. The weightings can be
used to give the system flexibility when deciding which parameters to adjust
(ex. the bit rate can be changed resulting in a poorer quality picture, but
don’t change the frame rate because the user is just using the video to watch
for presence of activity and that activity coul...
