Grass Valley Switcher Products - Manual (Page 133)

Switcher Products — Protocols Manual 133
Introduction
The values described in this document are shown as normally (big endian)
ordered bytes, but are written to the image files in little endian order.
Metadata File Format Versions and Kalypso Software Releases
The image metadata file format has evolved since the still store was first
released. This format is now at version 6, and only this metadata version is
described in this API.
Kalypso Release 7 and Zodiak Release 2 are the earliest software releases
that support the version 6 metadata format. Images created using this API
will only be usable on Kalypso or Zodiak systems running these or higher
releases of software. The Zodiak Release 2 software has not implemented
the animation or fencing features, but these features are supported in
Zodiak Release 3.
Images that use older format metadata will need to be resaved using a
Kalypso or Zodiak system running software that supports the version 6
metadata format before an application based on this API will be able to
access the images.
Metadata contents must reflect the content of the matching data file or the
still store will have problems reading the image. In severe cases, such
parsing errors could result in a still store or frame main processor crash.
Video Conversion
Most graphics applications produce “video” as red, green and blue compo-
nents. An alpha channel is sometimes included to control transparency of
the graphic in a final composite. Graphics systems do not necessarily gen-
erate images of the proper size for direct use by video systems. In addition,
pixels in the video domain are not square. The still store also expects inter-
laced video. It may be necessary to crop, aspect ratio convert, interlace or
otherwise manipulate the image spatially to conform to the video raster.
The alpha channel should be treated as a black and white video signal and
scaled accordingly.
The still store accepts video as Y, Cr and Cb. An optional “key” signal (a
black to white signal) may be included. The key correlates to the alpha
channel.
SD and HD images use different colorimetry. SD uses ITU-R BT 601 while
HD uses BT 709.