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OpalVision Programmers Technical Reference Manual Version 1.2 Copyright Opal Technology, 29th Sep, 1992 This manual was written by the OpalVision development team : - Martin Boyd - Prashant Maharaj - Gary Rayner - Robert Roy with special thanks to: - Centaur Development Inc. Copyright ⌐ 1992 by Opal Technology Pty Ltd. All rights reserved. No part of this publication may be copied, photocopied, reproduced, translated or distributed in any form or by any means, or stored in a data base or retrieval system, without the prior written permission of Opal Technology Pty Ltd. OpalVision is a trademark of Opal Technology Pty Ltd. Amiga and Workbench are registered trademarks of Commodore-Amiga, Inc. Opal Technology Pty Ltd, its employees and distributors, take no responsibility expressed or implied for the quality, performance, merchantability or fitness for any particular purpose of the information presented herein. The information in this manual is presented on an "As Is" basis. The user takes full responsibly for the quality, performance, correctness or any damage incurred by use of this information. Opal Technology Pty Ltd reserves the right to change information in this manual without notice. Opal Technology Pty Ltd, its employees and distributors will not under any circumstances be liable for any direct, indirect, incidental or consequential damages incurred by use of this information even if the possibility of such damage is known. TABLE OF CONTENTS INTRODUCTION 1.0 FEATURES OF THE OPALVISION MOTHER BOARD 2.0 THE OPALVISION SCAN RATE CONVERTER 3.0 THE OPALVISION VIDEO ROASTER CHIP 4.0 FUNCTIONAL DESCRIPTION OF VIDEO COMMUNICATION 5.0 DIGITIAL COMMUNICATION 6.0 COLOUR MODES 7.0 24Bit Modes 7.1 8Bit Modes 7.2 15Bit Mode 7.3 Colour Mode Selection 7.4 STENCIL MODES 8.0 Playfield Stencil 8.1 Priority Stencil 8.2 MEMORY STRUCTURE 9.0 REGISTERS 10.0 The Control Line Register 10.1 The CoPro 10.2 Palette Registers 10.3 Pixel Read Mask Register 10.4 Address Load Register 10.5 Video Command Register 10.6 Palette Load Register 10.7 The Video Roaster Chip 10.8 THE LIBRARY 11.0 The Opalscreen Structure 11.1 Types of Opalscreens 11.2 Drawing Routines 11.3 Frame Buffer Updating 11.4 Logical Frames 11.5 Dual Playfield Mode 11.6 Maniputlaing the Opalvision Registers 11.7 Screen Positioning 11.8 Horizontal Synchronization 11.9 Ownership 11.10 SUMMARY OF LIBRARY FUNCTIONS 12.0 Drawing Routines 12.1 Conversion Routines 12.2 Coprocessor Routines DEFINITION OF TERMS 13.0 ============================================================ 1.0 INTRODUCTION OpalVision is modular integrated 24bit graphics and video environment developed with total integration into the Amiga environment in mind. To maintain this philosophy the system has been designed to take advantage of the many specialized and highly productive hardware features of the Amiga. The OpalVision system provides the freedom and expandability to fit the specific needs of the user. Designed as one modular unit, OpalVision circumvents the usual problems with incompatibility and loss of signal integrity associated with the many external components available from separate third parties, and the "Rat's Nest" usually required to connect them. With the initial release of this product three expansion modules are available; The Frame Grabber Frame Grabber Genlock Module, the Scan Rate Converter Module and the Video Roaster Chip. The first two of these modules will be fully supported in the OpalVision development library. The modules connect directly to the OpalVision expansion card without tying up separate slots. Because of the expandable nature of the system Opal Technology strongly recommends strict adherence to the OpalVision Development Library. In the library we have included a comprehensive range of functions encompassing all modes and resolutions supported by the hardware. The library also includes OpalVision Screen Management , Drawing , IFF, Coprocessor, Virtual Screen, Display Control, Frame Grabber Control and Linear Keyer Control routines. If you find that the library has any inadequacies in relation to your specific application Opal Technology will gladly consider updating the library to suit your requirements. The OpalVision system offers an extremely cost effective entry into the world of high quality 24bit graphics. With the addition of the Frame Grabber + Genlock module and the sophisticated effects of the Video Roaster Chip, it offers an equally satisfactory solution to the world of Amiga desktop video. We at Opal Technology have attempted to provide a consistent and sustainable platform on which to build. Any suggestions or recommendations will be gratefully considered. 2.0 FEATURES THE OPALVISION MOTHER BOARD The OpalVision Mother Board is the heart of the OpalVision System. It is designed to reside in the Amiga 2000 or Amiga 3000 video slot. The OpalVision Mother Board is the most basic implementation of the OpalVision system. The OpalVision Mother Board incorporates a 24bit, 15bit and 8bit true colour modes, 24bit and 8bit Palette mapped display modes, Dual Playfield and Overlay Priority stencil modes and a graphics coprocessor. This range of modes provides the flexibility to meet the wide range of graphics requirements from animation to real time video effects to high resolution true colour graphics manipulation. OpalVision provides three different True Colour modes all of which are available in all supported resolutions. 24bit True Colour which provides one byte for each of the primary colours. This provides and effective colour range of 16.8 million colours. 15bit True Colour provides 5 bits of information for each of the primary colours. This provides an effective colour range of 32,768 colours. This mode has the advantage of higher speed updates due to its lower data requirements. Finally 8bit True Colour which provides 3bits of red, 3bits of green and 2bits of blue. With an effective colour range of 256 colours this mode provides high speed update at the expense of colour range. OpalVision also supports two different Palette Mapped colour modes. 24bit Palette Mapped passes all 24bits of data through three 8bit x 256 lookup tables immediately prior to display. Each lookup table corresponds to one of the primary colours. This feature is especially useful for contrast and gamma correction and for smooth fade image transitions. When coupled with the Frame Grabber it can also be used for real time effects with live video such as white balance, contrast and gamma correction, solarization, negative and colourisation effects. 8bit Palette Mapped is a standard palette mapped configuration allowing access to 256 colours from palette of 16.8 million (256 x 24bit palette registers). OpalVision incorporates two stencil modes; Overlay Priority stencil and Dual Playfield Priority stencil. Overlay Priority allows the OpalVision or the Amiga to be given foreground priority on a pixel by pixel basis. This is particularly useful for backdrop type applications where the speed and operating system advantages of Amiga graphics can be freely combined with the numerous advantages of OpalVision graphics. The Dual Playfield Priority provides foreground priority information between two OpalVision screens. This feature is especially useful for transitions between OpalVision images. The OpalVision graphics coprocessor has the ability to change OpalVision display modes and start address on a line by line basis. This provides the ability to freely change resolution, stencil modes, a host of transition effects and smooth scrolling between multiple adjacent screens. Below is a table of the most commonly used display resolutions available with OpalVision Low Resolution High Resolution Low Resolution Interlaced* High Resolution Interlaced* +--------------+------------+-----------+-----------+-----------+ |PAL | 320 x 256 | 640 x 256 | 320 x 512 | 640 x 512 | +--------------+------------+-----------+-----------+-----------+ |PAL Overscan | 384 x 286 | 768 x 286 | 384 x 576 | 768 x 576 | +--------------+------------+-----------+-----------+-----------+ |NTSC | 320 x 200 | 640 x 200 | 320 x 400 | 640 x 400 | +--------------+------------+-----------+-----------+-----------+ |NTSC Overscan | 384 x 236 | 768 x 236 | 384 x 476 | 768 x 476 | +--------------+------------+-----------+-----------+-----------+ *De-interlaced when Scan Rate Converter Present The OpalVision Genlock and Frame Grabber The OpalVision Genlock and Frame Grabber module is a true 24bit frame grabber, genlock, composite decoder (colour splitter), composite encoder, 256 level linear keyer with alpha channel output and live video effects processing system. It does not require a still frame or any sort of signal preparation for grabbing of images. The module is easily installed directly on to the OpalVision mother board and provides its configuration information to the library. The module has direct access to the memory and control systems of the OpalVision Mother Board and therefore appears as one seamless unit to the software. The Genlock and Frame Grabber Module will be fully supported by the library. The Genlock synchronizes both the OpalVision and the Amiga to an external video signal. This allows OpalVision or Amiga graphics to be overlaid on a live video signal. It also provides the timing and synchronization for the frame grabber and live video effects system. The Composite Decoder receives the incoming composite video signal and breaks it down into RGB video. This is the form required for both the frame grabber and live effects system. The Frame Grabber is directly connected to the main OpalVision memory through a 48 bit data bus. This enables it to digitize all three primary colours in parallel and at full frame rate while displaying the digitized video though all the special effects capabilities on the OpalVision Mother Board. e.g. Displaying live video with white balance correction, gamma correction, increased contrast and seen through an Overlay Priority Stencil with warping effects provided by the Coprocessor. Depending on the resolution the frame grabber is also capable of grabbing and storing multiple sequential frames which may easily be downloaded into Amiga memory for modification. The Composite Encoder converts the processed RGB. into composite or SVHS video for easy export to video equipment. The linear keyer offers the ability to set variable transparency between OpalVision graphics and live video on a pixel by pixel basis. OpalVision provides 256 levels of transparency which allows the user to implement complex titling effects and video overlay transitions. The linear keyer is capable of running at full frame rate in all resolutions. The OpalVision Genlock + Frame Grabber module provides a comprehensive array of features specifically designed for the desktop video industry. 3.0 THE OPALVISION SCAN RATE CONVERTER The OpalVision Scan Rate Converter is designed de-interlace and double the effective scan rate of the video signal so as to provide flicker free video for those users willing to invest in a high scan rate or multi sync monitor. The OpalVision Scan Rate Converter also provides flicker free Amiga and live video and is capable of acting as a fully independent frame buffer. 4.0 THE OPALVISION VIDEO ROASTER CHIP The OpalVision Video Roaster Chip is a reconfigurable hardware device situated between the address generation hardware and the memory address lines. This allows picture information to be redirected to different screen locations dynamically. This combined with the ability of the frame grabber and genlock module to continuously update the OpalVision memory with live video provides for a host of complex and flexible video effects which can be fully implemented in real time with no more than one field delay. The Video Roaster is a reconfigurable hardware device which adds another dimension to the systems flexibility. The Roaster is fully on the fly programmable from the Amiga therefore allowing the "Hardware" configuration to be changed. The Video Roaster will incorporate support for dynamically scaleable Picture in Picture as well as the Redirect Address Design (RAD). The Video Roaster Chip is a fully intergrated part of the OpalVision system and is therefore fully compatible with all other modules of the OpalVision system. For effective use, the Video Roaster Chip and software requires the Genlock and Frame Grabber Module. 5.0 FUNCTIONAL DESCRIPTION VIDEO COMMUNICATION The OpalVision communicates with video at several different levels. In its basic implementation the OpalVision is an output device with the ability to switch between Amiga and OpalVision video on a pixel by pixel basis. While inactive, the OpalVision simply passes through all Amiga graphics. While active the OpalVision has several modes which control the signal priority on a pixel by pixel basis and provide palette and lookup table effects on all output information. With the addition of the Frame Grabber + Genlock module the OpalVision becomes an input device with the ability to synchronize to a video signal, digitize at full frame rate and overlay Amiga and OpalVision graphics from Composite, RGB and SVHS sources. This provides several different paths for video information to follow as illustrated in the OpalVision System Flow Diagram. With the aid of the genlock and linear keyer, OpalVision graphics may be overlaid on live video with either pixel by pixel variable transparency or mixed Amiga and OpalVision graphics. Alternatively the live video may be digitized then displayed through the OpalVision Mother board with stencil priority and lookup table effects. With the addition of the OpalVision Video Roaster Chip much more complex live video effects are possible. The OpalVision unit functions in a synchronous manner for all functions except when using Video Roaster special effects. The Video Roaster effects induce a 1 field delay on to the signal this is the time required to implement a pixel remap. 6.0 DIGITAL COMMUNICATION The OpalVision receives its instructions and 24 bit data through the Amiga's 4 bit digital video output port. The Amiga is capable of outputing a maximum of 4 bits per Amiga pixel through this port. 8 bits of data is obtained by pairing up two 4 bit hi-res pixels side by side. This 8 bit data is then used by OpalVision as information for the CoPro, palette, or as an 8 bit per pixel update to the red, green or blue bank of 24 bit display memory. An activation control code must be present at the top of the Amiga display in the invisible overscan region of the screen to activate the OpalVision. All palette and CoPro updates are performed in the 3 scan lines following this code. Screen information is output to the OpalVision by a series of standard Amiga hi-res 4 bit screens. 8 bits per lo-res pixel is updated to the OpalVision by each Amiga screen. The OpalVision was designed to interface as closely as possible into the Amiga display architecture, philosophy, and environment. All of the benefits of the Amiga Intuition, Copper, Blitter and display hardware can be utilized to provide high speed screen updates, a variety of display modes, width control and effects to use on the 24 bit OpalVision graphics. You must have at least 8 bits of a 24 bit image residing in Amiga Chip RAM at a time to update a full 24 bit image into the OpalVision Memory. Memory Updates to the OpalVision are a continuous 5.5 megabytes per second. Using the copper and blitter, certain effects may be performed considerably faster than using the bus based C.P.U. The OpalVision memory and frame grabbed data is read back to the Amiga through the parallel port available on the video slot. See OpalVision System Flow Diagram OpalVision Programmers Tecnical Reference Manual 1.2 Page No. 11 7.0 COLOUR MODES 7.1 24Bit Mode 24Bit mode provides 24bits of information per pixel, 8bits of red, green and blue. There are two distinct ways in which this information may be dealt with, palette mapped or non palette mapped. In palette mapped mode, each 8bit value (for red, green and blue) is used as an index into a 256 entry 8bit palette. There are separate palette tables for each of the primary colours. The 8bit data is ANDed with the pixel read mask prior to accessing the palette. In non palette mapped mode, information is sent from memory directly to the display hardware by-passing the palette and the pixel read mask. 7.2 8Bit Modes 8Bit mode provides 8bits of data per display pixel. There are two distinct ways in which this information may be dealt with, palette mapped or non palette mapped. In palette mapped mode, each 8bit is used as an index into a 256 entry 24bit palette. This allows 256 colours from a palette of 16.8 million. In this mode the 8bit information is ANDed with the pixel read mask prior to entering the palette. In non palette mapped mode, the 8bit information for each pixel is divided into 3bits of red, 3bits of green and 2bits of blue. This produces an absolute 8bit colour value for each pixel. 7.3 15Bit Mode Unlike the 24bit and 8bit modes, 15bit mode is only available in non palette mapped form. 15Bit mode is not subject to the pixel read mask. 15Bit mode uses 5 bits of red, green and blue. 7.4 Colour Mode Selection The OpalVision colour modes are selected by combinations of the S1, S0 bits in the CoPro and CR7 and CR6 bits in the Video Command Register. +----+----+-----+-----+--------------+---------+---------+---------+ | S1 | S0 | CR7 | CR6 | Mode | R7-R0 | G7-G0 | B7-B0 | +----+----+-----+-----+--------------+---------+---------+---------+ | 0 | 0 | 0 | 0 |24Bit PMapped | R7-R0 | G7-G0 | B7-B0 | | 0 | 0 | 0 | 1 |24Bit PMapped | R7-R0 | G7-G0 | B7-B0 | | 0 | 0 | 1 | 0 |24Bit PMapped | R7-R0 | G7-G0 | B7-B0 | | 0 | 0 | 1 | 1 |Reserved |Reserved |Reserved |Reserved | +----+----+-----+-----+--------------+---------+---------+---------+ | 0 | 1 | 0 | 0 |24Bit By-Pass | R7-R0 | G7-G0 | B7-B0 | | 0 | 1 | 0 | 1 |24Bit By-Pass | R7-R0 | G7-G0 | B7-B0 | | 0 | 1 | 1 | 0 |24Bit By-Pass | R7-R0 | G7-G0 | B7-B0 | | 0 | 1 | 1 | 1 |Reserved |Reserved |Reserved |Reserved | +----+----+-----+-----+--------------+---------+---------+---------+ | 1 | 0 | 0 | 0 |8Bit PM Red | P7-P0 |Ignored |Ignored | | 1 | 0 | 0 | 1 |8Bit PM Green |Ignored | P7-P0 |Ignored | | 1 | 0 | 1 | 0 |8Bit PM Blue |Ignored |Ignored | P7-P0 | | 1 | 0 | 1 | 1 |Reserved |Reserved |Reserved |Reserved | +----+----+-----+-----+--------------+---------+---------+---------+ | 1 | 1 | 0 | 0 |8Bit RGB Red |RRRGGGBB |Ignored |Ignored | | 1 | 1 | 0 | 1 |8Bit RGB Green|Ignored |RRRGGGBB |Ignored | | 1 | 1 | 1 | 0 |8Bit RGB Blue |Ignored |Ignored |RRRGGGBB | | 1 | 1 | 1 | 1 |15Bit RGB |XRRRRRGG |GGGBBBBB |Ignored | +----+----+-----+-----+--------------+---------+---------+---------+ 8.0 STENCIL MODES OpalVision supports two different stencils which may function independently or together. These stencils are described below. 8.1 Playfield Stencil The playfield stencil provides pixel by pixel display priority between two screens currently in the frame buffer. This is made active by selecting the Dual Playfield mode. This mode is especially useful for fast dynamic transitions between OpalVision screens. Dual Playfield mode is completely independent of Priority mode and the two may be freely combined. This function is available in low resolution only. The Dual_Play control line register bit enables the playfield stencil as shown below. +-------------------+-----------+------+-----------------------+ | PlayField Stencil | Dual_Play | Bank | Memory Bank Dispalyed | +-------------------+-----------+------+-----------------------+ | Ignored | 0 | 0 | 1 | | Ignored | 0 | 1 | 2 | | 0 | 1 | 0 | 1 | | 0 | 1 | 1 | 2 | | 1 | 1 | 0 | 2 | | 1 | 1 | 1 | 1 | +-------------------+-----------+------+-----------------------+ 8.2 Priority Stencil Priority mode controls display priority between OpalVision and Amiga graphics on a pixel by pixel basis. There are several forms in which this mode functions. These are described below. +----------+-------+----------+-----------+-------------+--------------+ | Priority | Prior | Priority | Dual_Disp | Transparent | Actual Video | | Stencil | Mode | | | Colour | Display | +----------+-------+----------+-----------+-------------+--------------+ | Ignored | 0 | 0 | 0 | Amiga 0 | Amiga on Opal| | Ignored | 0 | 0 | 1 | None | Amiga Only | | Ignored | 0 | 1 | 0 | OpalVision 0| Opal on Amiga| | Ignored | 0 | 1 | 1 | None | Opal Only | | 0 | 1 | Ignored | 0 | Amiga 0 | Amiga on Opal| | 0 | 1 | Ignored | 1 | None | Amiga Only | | 1 | 1 | Ignored | 0 | OpalVision 0| Opal on Amiga| | 1 | 1 | Ignored | 1 | None | Opal Only | +----------+-------+----------+-----------+-------------+--------------+ The four control bits described above are situated in the CoPro register and can be updated on every scan line. The Priority Stencil is completely independent to the Playfield stencil and the two may be freely mixed. This mode is available in all resolutions. Resolutions OpalVision resolutions exactly matches Amiga low and high resolutions in both interlaced and non interlaced displays. This simplifies the use of Amiga/OpalVision stencil modes. All colour modes are available in all resolutions. OpalVision automatically configures for either PAL or NTSC. It is essential therefore that all software should auto configure for PAL and NTSC. And this can be done by opening all windows and screens using the size specified in GfxBase -> NormalDisplayRows, and when positioning gadgets at the bottom of the screen, do so by making them relative to the bottom of the screen by setting the GRELBOTTOM. Special consideration must be given to the limited screen resolution available in NTSC. 9.0 MEMORY STRUCTURE OpalVision memory is divided into two Banks and in turn each bank is divided into two fields. Each field is also divided into three regions one each for Red, Green and Blue. Interlaced pictures must be stored in adjacent fields. In non interlaced modes, these fields may be used to store separate images. In low resolution non-interlaced each of the four fields (Banks 1 and 2) can hold complete images. In low resolution interlaced both fields are required for each full picture therefore two complete images may be stored, one in each bank. In high resolution non interlaced, one bank is required for each picture allowing the storage of two complete pictures. Finally in high resolution interlaced, only one picture can reside in the OpalVision memory at a given time. Writing to the rams is controlled by the FIELD, RWR1, GWR1, BWR1, RWR2, GWR2 and BWR2 bits situated in the control line register. These bits are active high. Bits in the control line register are not mutually exclusive and may be used in any combination therefore multiple banks may be written with the same information simultaneously. This is most useful for memory initialization type operations. By the same token, it is possible to write to one bank while displaying another. This feature is especially useful for double buffered animation. Note however that it is not possible to write to one field while displaying the other field. In total there are 12 regions of memory which may be independently accessed, these are referred to as segments in this document.. Memory Segment Diagram RWR1 GWR1 BWR1 +--------------+--------------+--------------+ | | | | Field = 0 | 128K | 128K | 128K | | | | | BANK = 0 +--------------+--------------+--------------+ | | | | Field = 1 | 128K | 128K | 128K | | | | | +--------------+--------------+--------------+ Red Green Blue +--------------+--------------+--------------+ | | | | Field = 0 | 128K | 128K | 128K | | | | | BANK = 1 +--------------+--------------+--------------+ | | | | Field = 1 | 128K | 128K | 128K | | | | | +--------------+--------------+--------------+ RWR2 GWR2 BWR2 In low resolution non interlaced mode, picture information is stored in sequential form in one field. In interlaced modes sequential horizontal lines are stored in alternate memory fields as explained by the diagram. Interlaced +-------------------------------+ |OOOOOOOOOOOOOOOOOOOOOOOOO | |XXXXXXXXXXXXXXXXXXXXXXX | |OOOOOOOOOOOOOOOOOOOOO | |XXXXXXXXXXXXXXXXXXX | | | | | | | | | | | | | | | | | | | | | +-------------------------------+ OO = Even Field XX = Odd Field In high resolution modes, sequential pixels along each horizontal line are situated in alternate banks. High Resolution +-------------------------------+ |XOXOXOXOXOXOXOXOXOXOXOXOXOXO | |XOXOXOXOXOXOXOXOXOXOXOXOXO | |XOXOXOXOXOXOXOXOXOXOXOX | |XOXOXOXOXOXOXOXOXOXOX | | | | | | | | | | | | | | | | | | | | | +-------------------------------+ X = BANK 0 O = BANK 1 When high resolution and interlaced modes are selected at the same time, both these effects must be considered. Therefore sequential horizontal pixels are situated in alternating banks and sequential Horizontal lines are situated in alternating fields. The library provides a full compliment of memory format conversion routines to simplify the management of the OpalVision display memory and to convert between the different graphics memory configurations found on the Amiga. 10.0 REGISTERS 10.1 The Opal Control Line Register The Opal Control Line Register must be present to activate the OpalVision display. The Control Line Register provides control for memory write, display activation and auto display modes. It's Consists of 20 bits which are embedded in the first scan line of every Valid OpalVision frame. +------+------------+-------------------------------------------+------------+ | Bit# | Name |Description |Active State| +------+------------+-------------------------------------------+------------+ | 19 |*Freeze | Frame Freezes Current frame in SRC | 1 | | 18 |**VLSI_PROG | Program the Roaster chip if present. | 1 | | 17 |BWR2 Enable | Blue Video RAM write Bank 2 | 1 | | 16 |BWR1 Enable | Blue Video RAM write Bank 1 | 1 | | 15 |GWR2 Enable | Green Video RAM write Bank 2 | 1 | | 14 |GWR1 Enable | Green Video RAM write Bank 1 | 1 | | 13 |RWR2 Enable | Red Video RAM write Bank 2 | 1 | | 12 |RWR1 Enable | Red Video RAM write Bank 1 | 1 | | 11 |FGrab Enable| Frame Grabbing to Video RAM | 1 | | 10 |Latch | Latch On OpalVision display | 1 | | 9 |Field_Mode | Enable Auto Field Display Toggle | 1 | | 8 |FIELD | Field Toggle value | X | | 7 |Dual_Play | Dual OpalVision Playfield stencil enable | 1 | | 6 |AUTO Enable | Auto Line Start Sync | 0 | | 5 |COL/CoPro | Selects Palette update or CoPro Update | X | | 4 |WREN | Address Select for Register Updates | X | | 3 |Valid_3 | Valid OpalVision Activation Code | 0 | | 2 |Valid_2 | Valid OpalVision Activation Code | 1 | | 1 |Valid_1 | Valid OpalVision Activation Code | 0 | | 0 |Valid_0 | Valid OpalVision Activation Code | 1 | +------+------------+-------------------------------------------+------------+ *Available only when the Scan Rate Converter module is present. **Function for Live Video Manipulation Chip. **Available only when Roaster Chip is present. 10.2 The CoPro The OpalVision CoPro is a sequential processor which allows control of OpalVision display modes on a line by line basis. This is especially suited to transition effects like slides and wipes, between live and Amiga video. The Coprocessor offers the following control information on every display line . There are 290 available instructions in the CoPro list, one for each line of the display. +------+------------+-------------------------------------------+------------+ | Bit# | Name |Description |Active State| +------+------------+-------------------------------------------+------------+ | 7 | Add_Load | Re-load the address registers. | 0 | | 6 | Prior_Mode | Amiga/OpalVision priority stencil enable. | 1 | | 5 | Priority | Amiga/OpalVision priority. | X | | 4 | Dual_Disp | Mix Amiga/OpalVision graphics. | 0 | | 3 | Lo/Hi | Hi resolution enable. | 1 | | 2 | Bank | Video ram display bank selector | X | | 1 | S1 | Video display mode bit 1 | X | | 0 | S0 | Video display mode bit 0 | X | +------+------------+-------------------------------------------+------------+ 10.3 Palette Registers The OpalVision unit has a separate 256 entry palette for red, green and blue. This palette may be configured in two different ways. In 8bit palette mapped mode, it is organized as 256 24bit registers. This is a standard palette configuration. In 24bit palette mapped mode, the palette acts as three separate 8bit remap tables. These are especially useful for gamma correction, contrast stretching, negatives and smooth fades. All palette entries can easily be accessed through the library. 10.4 Pixel Read Mask Register The Pixel Read Mask Register is situated between video memory and the palette registers. The Pixel read mask is 8bits wide and is applied to red, green, blue or 8bit data prior to its entering the palette. This facility is available only in palette mapped modes. The same mask value is applied to all data paths. 10.5 Address Load Register The Address load Register is a 17bit register which can be loaded into the video address counters. Each address is equal to a low res pixel size. and there are 371 address counts per line. This value is independent of both the resolution of the Amiga or the OpalVision. Therefore scrolling the screen down one line may be achieved by simply adding 371 to the value. The value in this register is not loaded until a clear Add_Load bit in the CoPro register is encountered. 10.6 Video Command Register The Command register contains colour mode control bits. And output standard information. +------+------------+-------------------------------------------+------------+ | Bit# | Name |Description |Active State| +------+------------+-------------------------------------------+------------+ | 7 |CR7 | Colour Mode Select. See Video Mode Table | X | | 6 |CR6 | Colour Mode Select. See Video Mode Table | X | | 5 |Setup | Specifies 0 IRE or 7.5 IRE Pedestal use 0 | 0 | | 4 |8/6 | Selects between 6 (0) and 8 (1) bit mode | 1 | | 3 |Reserved | Keep Low | 1 | | 2 |Reserved | Keep Low | 1 | | 1 |VLSI_AD1 | *Ram Bank 1 address replace. | 1 | | 0 |VLSI_AD0 | *Ram Bank 0 address replace. | 1 | +------+------------+-------------------------------------------+------------+ *Functions for the Live Video Manipulation Chip (The Roaser). 10.7 Palette Load Register The Palette Load register is an 8bit register which is used to offset the palette updates. This makes it possible for the palette data to be shifted by the given amount for simple colour cycling effects. This register is normally 0. 10.8 The Video Roaster Chip The Video Roaster Chip is a reconfigurable hardware device which can be programmed from the Amiga. The Roaster is situated between the address counters and the memory address lines. This allows the roaster to redirect pixel information from any part of memory to any screen location. The Video Roaster requires the Frame Grabber and Genlock module to function. There will be atleast two different modules which take advantage of this capability these are the Picture in Picture module (PIP) and the Redirect Address Design module (RAD) These modules can only be used one at a time as they require the dedicated attention of the Roaster Chip. 11.0 THE LIBRARY 11.1 The Opalscreen Structure The library deals with OpalVision screens. These screens can contain 8, 15 and 24 bitplanes. Each screen is described by an OpalScreen structure. The contents of this structure is shown below. struct OpalScreen { SHORT Width; SHORT Height; SHORT Depth; SHORT ClipX1, ClipY1; SHORT ClipX2, ClipY2; SHORT BytesPerLine; UWORD Flags; SHORT RelX; SHORT RelY; struct MsgPort *UserPort; SHORT MaxFrames; SHORT VStart; SHORT CoProOffset; SHORT LastWait; UWORD LastCoProIns; UBYTE *BitPlanes[24]; UBYTE *MaskPlane; ULONG AddressReg; UBYTE UpdateDelay; UBYTE PalLoadAddress; UBYTE PixelReadMask; UBYTE CommandReg; UBYTE Palette[3*256]; UBYTE Pen_R; UBYTE Pen_G; UBYTE Pen_B; UBYTE Red; UBYTE Green; UBYTE Blue; UBYTE CoProData [MAXCOPROINS]; SHORT Modulo; UBYTE Reserved [38]; }; The fields have the following meanings: Width The width of the screen in pixels. This can be specified if the screen was created using CreateScreen24() or this value will be set automatically if opened using OpenScreen24(). Height The height of the screen in lines. This can be specified if the screen was created using CreateScreen24() or this value will be set automatically if opened using OpenScreen24(). When OpenScreen24() is used the number of lines depends on whether the machine is running in NTSC or PAL and also on the amount of available chip ram. Depth The number of bitplanes in the screen. This value is set when the screen is opened or created. ClipX1, ClipY1, ClipX2, ClipY2 These variables define the clipping region used by the drawing routines. The actual region is defined as ClipX1 <= x < ClipX2 and ClipY1 <= x < ClipY2. BytesPerLine This defines the screen width in bytes. This value is not always width/8 and depends on the resolution of the screen. Flags These flags may be specified when the screen is first opened using either OpenScreen24() or CreateScreen24(). These flags are: HIRES24 Screen is in high resolution mode (640 pixels across). The default is 320 pixels across. ILACE24 Screen is in interlaced mode. (512 lines for PAL , 400 lines for NTSC). The default is 256 lines for PAL and 200 lines for NTSC. OVERSCAN24 Screen is in an overscan mode. This is 368 pixels wide in low resolution or 736 pixels wide in high resolution. The number of lines in PAL is 286 non interlaced or 576 interlaced and in NTSC there are 236 lines in non interlaced or 476 lines interlaced. PLANES8 Screen has 8 bitplanes. PLANES15 Screen has 15 bitplanes. CLOSEABLE24 The screen can be closed by a higher priority task (display screen only). PALMAP24 Screen is in palette mapped mode. CONTROLONLY24 This flag can be used to activate the OpalVision to allow updating of the internal registers only. The following flags are set by the library and are not user definable: NTSC24 Screen is in NTSC mode. Default is PAL. INCHIP24 Screen is a display screen in chip ram. RelX, RelY These variables provide a relative drawing origin which is used by the drawing routines. These values are simply added to the input coordinates of drawing routines. UserPort This is a message port opened specifically for the screen. In this version of the library this is only used for close down messages to tasks which have opened a screen with the CLOSEABLE24 flag set. MaxFrames This field is set when the screen is opened and defines how many screens of this resolution may be held in frame buffer memory. VStart This field is set when the screen is opened and defines the starting scan line of the screen. This is normally defined in preferences or is given a default value for overscan screens. This value is useful for building user copper lists. CoProOffset This field is set when the screen is opened and defines the CoPro instruction number corresponding to the first scan line in the display. LastWait This field contains the scan line number of the last vertical position wait for a display copper list. Normally this is the top of the display, but must be updated if copper lists are added to the display lists using the AppendCopper24() function. LastCoProIns This field defines the last CoPro instruction which can be modified. Normally this is MAXCOPROINS, however it will be less than this if a display bottom has been set. BitPlanes This field is an array of pointers to the bitplanes for the screen which will contain 4, 8, 12, 16 or 24 entries. MaskPlane This can point to a single bitplane mask plane which is allocated if LoadImage24() loads a file which contains a mask plane and the LOADMASK24 flag is set. Likewise this plane is saved in the file if the SaveIFF24() function is called with the SAVEMASK24 flag set. AddressReg This field holds a copy of the Address Load Register in the OpalVision. Values written to this register are not updated in the OpalVision until SetLoadAddress24() is called. UpdateDelay This field defines the number of frames to wait between consecutive frame buffer updates. This field should not be set directly but set using a call to UpdateDelay24(). PalLoadAddress This field holds a copy of the Palette Load Address Register in the OpalVision. Values written to this register are not updated in the OpalVision until RegUpdate24() is called. PixelReadMask This field holds a copy of the PixelReadMask Register in the OpalVision. Values written to this register are not updated in the OpalVision until RegUpdate24() is called. CommandReg This field holds a copy of the Command Register in the OpalVision. Values written to this register are not updated in the OpalVision until RegUpdate24() is called. Palette This contains a copy of the OpalVision's internal palette. The palette consists of 256 entries of Red, Green and Blue triplets. Values written into the palette will not be updated in the OpalVision until UpdatePalette24() is called. Pen_R, Pen_G, Pen_B These three fields hold the current pen value used by the drawing routines. For 24bit screens all three are used, while in 15bit screens only Pen_R and Pen_G are used and in 8bit mode only Pen_R is used. Macros are defined in Opallib.h to simplify setting pen values. Red, Green, Blue These three fields contain the return values from ReadPixel24(). For 24bit screens all three are used, while in 15bit screens Red and Green are used and in 8bit mode only Red is used. Macros are defined in Opallib.h to simplify getting these values. CoProData This array holds a copy of the CoPro instructions in the OpalVision. Values written into this array are not updated in the OpalVision until UpdateCoPro24() called. Modulo This field holds the line width in pixels used for the 24 bit display, this value is a constant independent of display resolution. This value is required for calculating addresses to place in the address register. This value is different for the ColorBurst and the OpalVision. Reserved Reserved for future expansion. 11.2 Types of Opalscreens There are two types of OpalScreens. The display screen is the main screen which is opened using the OpenScreen24() function. All library calls are applicable to the display screen which can be used to update the frame buffer memory and is hence displayable. The display screen's bitplanes must reside in chip ram and its size may therefore be restricted by the available chip memory. Virtual OpalScreens can be opened using the CreateScreen24() function. These screens reside in fast ram and therefore cannot be directly displayed. Virtual screens are more flexible than display screens in that they can be opened in any size (memory permitting). Virtual screens are useful for file conversion, image processing or implementing virtual screen support where a large image is stored in fast ram and a smaller scrollable display window is held in chip ram. The fields in the OpalScreen structure pertaining to display attributes, such as the palette, CoPro instructions and registers are ignored for virtual screens. Library functions pertaining to display modes cannot be used for virtual screens and normally do not take an OpalScreen parameter implying that they operate on the display screen. Display screens can also be opened as low priority closeable screens by setting the CLOSEABLE24 flag when opening a screen. If another task tries to open a display screen, a message will be sent to the screens message port requesting that it be closed to enable the other task to open its screen. This is useful for backdrop type programs. An example of using a closeable screen is given below, note that the screen MUST be closed before the message is replied to. OScrn = OpenScreen24 (CLOSEABLE24); if (OScrn!=NULL) { WaitPort (OScrn->UserPort); CloseScreen24(); Mesg = GetMsg (OScrn->UserPort); ReplyMsg (Mesg); } Virtual screens can be displayed indirectly using the LowMemUpdate24() function, this function updates the buffer one segment at a time and therefore only requires one segment of data to be in chip memory. If you only require one off updates of the buffer, this method is strongly recommended as it does not suffer from chip ram limitations. 11.3 Drawing Routines All drawing routines are applicable to both types of OpalScreens and take a screen pointer to define which OpalScreen is used. Within the screen structure there are several fields which apply only to drawing. The ClipX1, ClipY1 and the ClipX2, ClipY2 fields define an absolute clipping rectangle defining the allowable drawing area. Pixels outside of this rectangle will be unaffected. The clipping rectangle is initialized to the size of the screen when it is created. The RelX, RelY fields define the origin of the drawing coordinate system. This is initialized to 0 when the screen is opened. The drawing routines use the Pen_R, Pen_G and Pen_B fields of the screen structure to define the colour used for drawing. In 24bit mode the three values contain 8bits of red, green and blue. In 8bit mode, Pen_R contains the 8bit value to be written. In 15bit mode the Pen_R and Pen_G contain 5 bits of red, green and blue compressed together as shown below. Pen_R Pen_G 15bit Pen value 0RRRRRGG GGGBBBBB 8bit true colour pen value RRRGGGBB To simplify writing pen values, the following four macros are defined in Opallib.h: SetPen24 (Screen, R,G,B) - Set 24bit pen SetPen15 (Screen, R,G,B) - Set 15bit pen SetPen8P (Screen, Pen) - Set 8bit Palette mapped pen. SetPen8 (Screen, R,G,B) - Set 8bit true colour pen. Similarly the values returned by ReadPixel24() are returned in the Red, Green, Blue fields of the OpalScreen structure in the same format. To get the components of the returned value the following macros can be used. GetCol24 (Screen, R,G,B) - Get 24bit colour. GetCol15 (Screen, R,G,B) - Get 15bit colour. GetCol8P (Screen, Pen) - Get 8bit Palette mapped pen number. GetCol8 (Screen, R,G,B) - Get 8bit colour. 11.4 Frame Buffer Updating When instructed the library updates the frame buffer with the contents of the current display screen. Making any changes to the current screen visible. The library allows two different methods for updating the frame buffer. The first method is to make the changes that you wish to the display screen in memory and then call Refresh24() which will refresh the frame buffer in the minimum number of frames required for that resolution, stops updates and then returns. This form of updating has the nice side effect of providing inherent double buffering. The second method is to allow continuous updating of the frame buffer which is performed transparently by the library. This mode is enabled by calling UpdateDelay24() which also allows for a delay parameter to be specified which sets a frame delay between consecutive updates. StopUpdate24() can be used to cease updating. Note that while frame buffer updates are occurring the CPU access to chip ram will be limited, the frame delay between buffer updates gives the CPU a little breathing room and will increase CPU throughput . 11.5 Logical Frames Frame buffer memory can contain several images depending on the resolution and display mode. The library divides the frame buffer memory into a number of logical frames to ease the task of writing several frames into the buffer. The frame to be updated is set by calling WriteFrame24() and the current display frame is set by calling DisplayFrame24(). The maximum number of frames possible is given by the MaxFrames field in the OpalScreen structure. The following tables show the assignments of logical frames to physical memory segments. Table: Frame Assignments in 15 and 24 Bit Modes Resolution Frame Number Table: Frame Assignments in 8Bit Mode The following information contains terms which should be understood clearly for an effective understanding of the OpalVision's operating modes. It is worth spending a moment to understand the characteristics and differences between a Dual Display and Dual Playfield as well as the Priority Stencil and the Playfield Stencil. Dual Display Mode The OpalVision can operate in a dual display mode. When activated, this enables both Amiga and OpalVision graphics to be visible on the same screen. The priority of the display can also be set to enable either Amiga over OpalVision or OpalVision over Amiga. This mode enabled by calling DualDisplay24() and disabled by calling SingleDisplay24(). The Priority is set using OVPriority() and AmigaPriority(). A priority stencil can also be used to set the priority between OpalVision and Amiga graphics on a pixel by pixel basis. The priority stencil is enabled by calling EnablePRStencil24() and disabled with DisablePRStencil24(). The functions SetPRStencil24(), ClearPRStencil24(), WritePRPixel24() and ReadPRPixel24() are provided to help manage the priority stencil. Note that when updating the frame buffer in dual display mode, the information being sent out to the OpalVision will be visible and cause a glitchy display. To avoid this the dual display should be turned off when updating and OpalVision priority should be set. The following function is useful to allow glitch free updates, note that it also blanks the sprite during updates so that the sprite will not be written into the frame buffer. void Refresh_Display (void) { OVPriority (); SingleDisplay24 (); /* Set up 24bit only display */ SetSprite24 (NullPointer,0L); /* Turn off sprite */ Refresh24 (); /* Update frame buffer */ DualDisplay24 (); /* Enable dual Amiga/24 bit display */ AmigaPriority (); /* Amiga over 24bit display */ SetSprite24 (Pointer,0L); /* Reinstall sprite */ } 11.6 Dual Playfield Mode Dual Playfield mode allows two low resolution 24bit OpalVision images to be overlaid. This can be achieved by writing two frames into the frame buffer memory using the WriteFrame24() function and calling DualPlayfield24() to enable dual playfield mode. SinglePlayfield24() can be used to revert back to single playfield mode. When in dual playfield mode a playfield stencil is used to determine which frame is displayed on a pixel by pixel basis. The functions SetPFStencil24(), ClearPFStencil24(), WritePFPixel24() and ReadPFPixel24() are provided to help manage the playfield stencil. The function UpdatePFStencil24() can be used to speed up the updates to the frame buffer so that all consecutive updates will only update the memory segments containing the playfield stencil. Using a combination of this and the above playfield routines fast wipes, dissolves and other transition effects can be achieved. After UpdatePFStencil24() has been called, it takes only one field to update a non interlaced stencil, and two fields (1 frame) for an interlaced one. Normal updating can be restored by calling UpdateAll24() 11.7 Manipulating The Opalvision Registers The Library allows for direct manipulation of all the OpalVision registers through library calls. These all involve modifying a copy of the register in the screen structure and calling a library function to update the hardware registers. Also using this method custom CoPro lists can be built and updated into the OpalVision. It is important to be aware that all hardware register updates occur during the vertical blanking period, and your program must synchronize to this and wait for the update to complete before attempting to modify the registers again. If the program is not synchronized, data may be lost. The function RegWait24() is available for this purpose. RegWait24() should also be called after calling any another library function which affects internal registers, the CoPro or the palette. 11.8 Screen Positioning Version 2.0 and later of the Amiga Operation System supports an overscan WorkBench screen. If an overscan display is active, the library will centre non-overscan OpalVision screens in the overscan region. If you wish to open an Amiga Screen as an overlay, it will also need to be centred to maintain alignment between the Amiga and 24 bit displays. The following code can be used to centre the Amiga intuition screen: void Centre_Screen (struct NewScreen *NewScrn, ULONG ModeID) { struct Rectangle Rect; SHORT Width; if (IntuitionBase->LibNode.lib_Version<36) return; if (!QueryOverscan (ModeID,&Rect,OSCAN_TEXT)) return; Width = Rect.MaxX - Rect.MinX + 1; /* Calculate overscan width */ Width = (Width - NewScrn->Width)/2; /* Calc center X position */ NewScrn->LeftEdge = MAX (Width,0); } Call Centre_Screen (&NewScreen,DisplayID) before opening the intuition screen. DisplayID should be a standard 2.0 DisplayID such as PAL_MONITOR_ID|HIRES_KEY. NOTE: The Centre_Screen() code provided in previous revisions of this manual was incorrect, if you have used the Centre_Screen() function previously it should be changed to the above code. Also note that it is not possible to display OpalVision graphics while the Amiga display is in a high scan mode as available with the AA chip set. To avoid this problem, programs like Show24 should open an intuition screen over the workbench screen to drop the Amiga display back into a standard scan rate. IMPORTANT NOTE: If you are opening an Amiga intuition screen as either a backdrop or as or an overlay for menus, you must ensure that it is a 15KHz screen, this means that Mode Promotion available under AmigaDOS3.0, if enabled, must not promote your intuition screen to 31KHz. To avoid this you must open a screen using the DisplayID tags either via OpenScreenTags() or using an ExtNewScreen structure. The correct DisplayID's should be either PAL_MONITOR_ID or NTSC_MONITOR_ID OR'ed with the correct resolution flags. 11.9 Horizontal Synchronisation To maintain the OpalVision's horizontal synchronisation with the Amiga's video the OpalVision uses the Amiga's output to detect the start of each scan line. Some consideration has to be given to this when writing software for the OpalVision. There are two horizontal synchronisation methods that can be used. The first method is to set the least significant bit of blue for the background colour. The OpalVision then uses the low to high transition of the LSB of blue as the start of line indicator. This is the preferred method as it provides exact synchronisation with the Amiga's display. When writing programs which use an Amiga overlay to contain gadgets and menus, this is easily achieved by using the LoadRGB24() graphics library function. (i.e. if you are setting colour 0 to black, use 001 rather than 000). Sometimes it is not possible to ensure that the LSB blue of the background colour is set, if you are not opening an Amiga screen for example, we cannot assume that the LSB blue is set on the users WorkBench screen (set in preferences). In these situations, the OpalVision can be put into an auto sync mode, it then uses a constant horizontal blanking period which can be up to 2 hi-res pixels out of phase with the Amiga's display, this simply means that the 24bit output can be shifted up to 2 pixels to the left of the Amiga's graphics. This mode can be enabled and disabled by calling AutoSync24(). The autosync mode however cannot be used while updating the frame buffer, and the library will automatically disable this mode while updating is occurring, note that the 24 bit display will always be in sync with the Amiga's graphics while updating the frame buffer. Using the auto-sync mode can then have the effect of causing the 24bit display to shift from left to right when jumping in and out of buffer updating mode. 11.10 Ownership The OpalVision library is basically a passive entity, it contains a set of functions to make access to the OpalVision hardware easier. The only active part of the library is a vertical blanking interrupt handler which is always active while a display screen is open. the interrupt handlers' only function is to update the copper lists required to display the screen. Any memory or resources allocated via the library calls are therefore owned by the calling program, in simple terms, a display screen opened using OpenScreen24() must be later closed by calling CloseScreen24(), similarly all virtual screens opened by calling CreateScreen24() must be closed by calling FreeScreen24(). The Lowmemupdate functions also have the side effect of opening a display screen, this means that after calling LowMemUpdate() (or the other versions of this function) you will actually have 2 screens open, one display and one virtual, the display screen opened by LowMemUpdate() MUST be closed by calling CloseScreen24(). All screens opened by calling LoadImage24() must also be closed. 12.0 SUMMARY OF LIBRARY FUNCTIONS 12.1 Drawing Routines ClearPFStencil24 - Clears the playfield stencil ClearPRStencil24 - Clears the priority stencil ClearScreen24 - Clears all bitplanes in a screen DrawEllipse24 - Draw an ellipse in the designated screen structure DrawLine - Draw a line in the designated screen structure ReadPFPixel24 - Reads the state of the specified playfield pixel ReadPixel24 - Returns colour information for a given pixel ReadPRPixel24 - Reads the state of the specified priority pixel RectFill24 - Draws a solid rectangle in a screen SetPFStencil24 - Sets all bits in the playfield stencil to 1 SetPRStencil24 - Sets all bits in the priority stencil to 1 SetScreen24 - Fills screen with a colour WritePFPixel24 - Writes Dual Playfield stencil information WritePixel24 - Writes a pixel WritePRPixel24 - Writes Overlay priority stencil information Memory 12.2 Conversion Routines BitPlanetoOV - Converts a standard bit planes to OpalVision format ILBMtoOV - Converts interleaved bitmap to OpalVision format OVtoBitPlane - Converts OpalVision format to standard bit plane format OVtoILBM - Converts OpalVision format to interleaved bitmap format OVtoRGB - Converts OpalVision format to red, green and blue byte planes RGBtoOV - Converts red, green and blue byte planes to OpalVision format File I/O Routines LoadImage24 - Loads JPEG, 24bit IFF, Fast Format 24bit,Palette Mapped (up to 256 colours), Hold and Modify and Extra Half Brite files SaveIFF24 - Saves an OpalScreen as an IFF interleaved bitmap file with 24bit Thumbnail SaveJPEG24 - Saves an OpalScreen as an JPEG JFIF file with 24bit Thumbnail WriteThumbnail24 - Writes a Thumbnail chunk for the specified screen to a specified file 12.3 Coprocessor Routines AmigaPriority - Gives Amiga priority over OpalVision graphics DualPlayField24 - Initiates OpalVision 24bit Dual Playfield mode OVPriority - Gives OpalVision priority over Amiga Graphics SetCoPro24 - Modifies a single instruction in the CoPro list SinglePlayField24 - Sets single playfield Mode UpdateCoPro24 - Updates coprocessor instructions to the OpalVision Display Control Routines ActiveScreen24 - Returns pointer to currently displayed OpalVision screen AppendCopper24 - Append Amiga copper lists to currently displayed copper list ClearDisplayBottom24 - Resets the OpalVision Display Bottom DisablePRStencil24 - Disables the use of priority stencil in dual display mode EnablePRStencil24 - Enables the use of priority stencil in dual display mode DualDisplay24 - Sets up an Amiga/OpalVision dual display FadeIn24 - Fades any palette mapped display from black in a specified time FadeOut24 - Fades any palette mapped display to black in a specified time LatchDisplay24 - Latch the OpalVision display. LowMemUpdate24 - Low Chip Memory usage frame buffer update. LowMem2Update24 - Low Chip Memory usage frame buffer update. LowMemRGB24 - Low Chip Memory usage frame buffer update from an RGB array. PaletteMap24 - Enables or disable palette mapping Scroll24 - Scrolls currently displayed image by a given distance SetDisplayBottom24 - Sets the OpalVision display bottom SetRGB24 - Sets a single palette entry SingleDisplay24 - Sets up an Amiga or OpalVision single display UpdatePalette24 - Updates palette information to the OpalVision Frame Buffer Management ClearQuick24 - Clear all OpalVision frame buffer memory CloseScreen24 - Closes the currently displayed screen and frees resources Config24 - Returns Hardware configuration information CreateScreen24 - Creates an arbitrarily sized virtual OpalScreen DisplayFrame24 - Sets the currently displayed frame within the frame buffer memory FreeScreen24 - Frees a virtual OpalScreen FreezeFrame24 - Freezes the currently displayed screen. (requires Scan Rate Converter) OpenScreen24 - Allocates all resources and displays an OpalVision screen Refresh24 - Refreshes information in the frame buffer memory RegWait24 - Waits for the completion of register updates SetControlBit24 - Modifies a bit in the control line data SetLoadAddress24 - Updates the OpalVision load address register SetSprite24 - Sets Amiga sprites on OpalVision display StopUpdate24 - Stops updates to the frame buffer memory UpdateAll24 - Resets the internal update structure so all required banks are updated UpdateDelay24 - Allows user definable update frequency UpdatePFStencil24 - Continuously update Dual Playfield stencil only UpdateRegs24 - Updates pixel read mask, palette load address and control register WriteFrame24 - Sets the current frame to be written within the frame buffer memory Frame Grabber Control 13.0 DEFINITION OF TERMS The following library function description is given in standard C calling conventions. The terms used are described here for non C programmers. void -This specifies that there are no return values or input parameters. USHORT -An unsigned 16bit integer. UBYTE -An unsigned byte. long -A signed 32bit integer. BOOL -A 32bit boolean value. FALSE = 0, any non zero value is TRUE. struct OpalScreen *OScrn -A pointer to an OpalScreen structure described previously. UBYTE **Array[] -A pointer to an array of pointers to UBYTE sized memory. long (*Function)() -A pointer to a function (routine) which returns a long result in D0. NULL -A NULL pointer value (0). BPTR -A BCPL pointer returned by a DOS Open() call.