Browse Prior Art Database

Method for Enhancing Video Capture

IP.com Disclosure Number: IPCOM000118054D
Original Publication Date: 1996-Aug-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 84K

Publishing Venue

IBM

Related People

Flurry, GA: AUTHOR

Abstract

Disclosed is a method for enhancing a video capture capability. The method comprises the ability to capture high resolution still images and to determine missed fields when capturing real-time video images.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Method for Enhancing Video Capture

      Disclosed is a method for enhancing a video capture
capability.  The method comprises the ability to capture high
resolution still images and to determine missed fields when capturing
real-time video images.

      The method assumes the video capture hardware supports two
functions.  The hardware must generate an interrupt after a field has
been captured; it is generated at the vertical sync at the beginning
of the next field.  The hardware must also allow identification of
the field that has just been captured, or must allow choice of the
field to be captured (some hardware does both).  The method also
requires an operating system device driver that can handle the
interrupts generated by the hardware.

      To capture a high resolution still image, both the odd and even
fields of a video frame must be captured.  The method the allocates
the required memory in the capture hardware to hold both captured
fields.  The method must first synchronize with the video signal to
be assured of getting the odd and even fields from the same frame.
To do so, the device driver tells the hardware to capture only the
odd fields; the driver waits for an interrupt generated by the an odd
field.  While the device driver services that interrupt, the hardware
is skipping the even field, since it was told to capture only the odd
fields.  The device driver now tells the hardware to capture both
fields and waits for further interrupts.  This ensures that the
subsequent odd and even fields captured belong to the same frame,
because the hardware cannot start capturing until the beginning of
the next odd field.

      The hardware captures the next odd field and generate an
interrupt.  The device driver ignores that interrupt since both
fields are required.  The hardware continues to capture the even
field of the same frame and generates another interrupt.  Now the
device driver gets invoked again and finds that both fields are
captured.  At this point, the device driver has the odd field in one
buffer and the even field in a second buffer.  To give the
application a non-interlaced still frame, the device driver must copy
the field buffers to application memory i...