The University of Arizona, Department of Computer Science
NetCAM
Overview
NetCAM is a Scout-based network appliance that captures frames from
a video source, MPEG-compresses them, packetizes the frames, and transmits
them over a network. A given video stream is implemented by a Scout path
that runs from the device driver for the video capture card to the network
device driver. NetCAM includes a previewer that displays the captured video
locally. NetCAM includes a flow control protocol that adapts the transmission
rate according to the capacity of the network and the destination machine;
e.g., NetTV.
Research Goals
- End-to-End Paths. Scout paths are defined within a single system,
but in as much as a path can be viewed as an extension of a network connection,
it makes sense to think of paths on an end-to-end basis (i.e., from the
source OS, across the network, to the destination OS). NetCAM, along with
NetTV, provide an opportunity to develop such
end-to-end paths. How the user specifies the collection of modules along
the end-to-end path is also of interest.
- Adaptive Video Application. Video is a very pliable data type
because it's quality, frame rate, and resolution can all be changed. An
important feature of NetCAM is its ability to adapt the video stream in
response to feedback received from the network and the destination machine.
Understanding the best way to adapt video to changing conditions is a central
research question of this work.
- Software-Based MPEG. We are investigating implementation techniques,
including dynamic code generation, that will allow us to do MPEG compression
in software at realistic rates.
Router Graph
Status
- MPEG compression currently runs at 11 frames-per-second on a 300MHz
Alpha.
- MFLOW paces transmission according to flow control information from
the destintation as well as adapting to network congestion.
- The Scout device driver for the Matrox Meteor frame capture card is
complete enough for NetCAM to use.
- NetCAM can also encode frames from NFS files and/or write the encoded
video to an NFS file.
Papers
Contributors
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Last updated March 2, 1998