User`s manual

DIGITAL-LOGIC AG MSLB-P5 Manual V0.3
PRELIMINARY 87
4.11.1 HiQVideo Series Programming Examples
4.11.2 Introduction
This application note shows how the CHIPS HiQVideo??Series controllers can be used for video capture and
playback. This document includes a description of the hardware configuration, a discussion of the functions, and
actual programming examples.
4.11.3 Video Playback through PCI/VL Bus
The new generation of Chips and Technologies, Inc. Multimedia Accelerators (6555x) supports Color Space Con-
version and Stretching (Zooming) in the back end with the chroma color key. The color space conversion func-
tionality of the 6555x can be made available to video codecs by implementing the off-screen surface support in
the DCI Provider (Windows 3.1 drivers). Only the playback feature of 6555x multimedia module is used to imple-
ment extended DCI functionality. This means the video input to the 6555x is kept in the frozen state (not grabbing)
when DCI is running. For video playback, the CPU can write YUV, RGB15, and RGB16 data into the off-screen
memory and fill the destination rectangle (where video need to be displayed on the visible screen) with the color
key. Video can be zoomed up if the destination rectangle is bigger than the source rectangle in the off-screen
buffer.
4.11.4 Video Capture and Playback Through Video Port
The new generation of CHIPS Multimedia Accelerators (69000) can also capture live video from the video port
into the off-screen memory and play it back with color space conversion onto a color keyed destination rectangle
on the visible screen. Playback video can be zoomed up to fill the bigger destination rectangle while incoming
video can be scaled down to fit into a smaller off-screen memory buffer or smaller destination rectangle. Zoomed
video can be smoothed out with horizontal and vertical interpolation. Scaled down video can also be filtered out at
input before capturing into the frame buffer. Input video can be cropped for the extra data which is usually associ-
ated with the NTSC or PAL video. The 69000 hardware can accommodate fast or slow capture applications
through the CPU Bus by capturing the video frames in one of three methods: continuously, one frame at a time,
or one every nth (n = 1-15) frame. Following diagram demonstrates the video capture.
VideoRect comes from the input video stream fed through the Video Port (VAFC / ZV Port) and comprises of one
of the following sizes based on the input source.
NTSC: 640x480 60 fields / second (interlaced), Square Aspect Ratio (4:3).
720x486 60 fields / second (interlaced), Non-square Aspect Ratio.
PAL: 768x576 50 fields / second (interlaced), Square Aspect Ratio (4:3).
720x576 50 fields / second (interlaced), Non-square Aspect Ratio.
MPEG1: 320x240 30 frames / sec (non-interlaced), Square Aspect Ratio (4:3).
352x288 30 frames / sec (non-interlaced), Non-square Aspect Ratio.
Top-left of VideoRect is always at (0,0).
CropRect is defined relative to the VideoRect. CropRect is used to crop off some pixels from the top, left, right,
or bottom to fit the image into a square pixel ratio or to drop some unwanted pixels. CropRect is programmed
using the acquisition window registers After cropping, the video is scaled down to fit into a smaller memory buffer
or in a smaller display window. The scaled video is captured into off-screen video memory buffer or buffers (as in
double buffer mode). There is a horizontal filter to reduce the sampling artifacts caused by input video scaling.
Video in the capture buffer is displayed on top of the pixels which matches the color key and/or with a specified
rectangular window.
4.11.5 ZoomUp
If client area of a window (DispRect) is larger than the capture buffer rectangle (CaptRect), the video can be
zoomed up to fit into the DispRect.