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Handling Hardware Access Conflicts in Video Systems

IP.com Disclosure Number: IPCOM000116476D
Original Publication Date: 1995-Sep-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Sethi, V: AUTHOR

Abstract

In a Person-to-Person (P2P) Video Conferencing system using the Video for Windows* architecture, there is the capability to Capture and Display a video data stream. Some adapters will allow for simultaneous Capture and Display, whereas others will only allow for Capture with any simultaneous display being routed to a code where it will be rendered in software.

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Handling Hardware Access Conflicts in Video Systems

      In a Person-to-Person (P2P) Video Conferencing system using the
Video for Windows* architecture, there is the capability to Capture
and Display a video data stream.  Some adapters will allow for
simultaneous Capture and Display, whereas others will only allow for
Capture with any simultaneous display being routed to a code where it
will be rendered in software.

      In a two-party call, if the captured stream is being sent to a
station that is already capturing and the adapter on that machine
cannot render to hardware then the stream will be rendered to
software
using the DrawDib calls that are provided for a Video for Windows.

      Where the captured video stream is sent to a station that can
have the video hardware render the stream again using DrawDib the
process is generally effective, for example where the real time
aspect is important in collaborative working.  However, a difficulty
arises when the second instance of the video application wishes to
start capturing from the video hardware that is already being used to
display the incoming video stream, i.e., the hardware cannot perform
simultaneous Capture and Display.

      The problem can be overcome by relinquishing the DrawDib handle
which was claimed and stored using DrawDibOpen.  VideoOpen is then
caused to make another attempt to use the video hardware.

      Once the capture is in use ready to start capturing video
streams, t...