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Top Forums UNIX for Advanced & Expert Users Video Cards :: Video Memory Intercept and Redirect Post 302482780 by ciNG on Wednesday 22nd of December 2010 01:45:28 PM
Old 12-22-2010
Video Cards :: Video Memory Intercept and Redirect

I need a broad spectrum understanding on this subject, and any help would be greatly appreciated.

First of all, as I understand it...
The way the video hardware works is the CPU sends information about input and possible changes to the display, the video card receives these changes, makes the necessary changes to its memory cache, and then sends out the new information to the display.

Input -> CPU -> VideoCard -> Display

...now this is a very simple understanding, if you can blow my mind by proving my ignorance with more specific and technical semantics it would be greatly appreciated. I feel my personal research has plateaued beneath the necessary esoteric terminology.

Next I want to know how I can get at those arrows inbetween. Are there ways, software'hardware, to pipe the raw data, binary, traveling between these points into another destination for manipulation andor examination purposes?

Thirdly, if there is a built in video card in my motherboard and also a supported third party videocard, how can I tell my computer to use the third party card? Is this a kernel config thing? Modules? A HALd thing? I know the actual setting up of this is a simple process. I am not looking for a tutorial how to do this, I want to know how the computer learns to do it as a result of my telling it to do so.

Finally, I have been running around a number of repositories like an asshole with his head chopped off looking for clues to these answers. I've looked into HAL, VNC, X, udev, pciutils, but honestly I don't know where to begin, or what I'm looking for within their respective functions. They all just seemed to harness, in one way or another, this thing I am looking for...

If this question is too big or obtuse, and someone wants to just say: read this; also very much appreciated.
 

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pods::SDL::Overlay(3pm) 				User Contributed Perl Documentation				   pods::SDL::Overlay(3pm)

NAME
SDL::Overlay - YUV Video overlay CATEGORY Core, Video, Structure SYNOPSIS
First import the following modules to get access to constants and functions needed for overlay. use SDL; use SDL::Video; use SDL::Overlay; Init the video subsystem. SDL::Init(SDL_INIT_VIDEO); Create a display to use. my $display = SDL::Video::set_video_mode(640, 480, 32, SDL_SWSURFACE); Create and attach the display to a new overlay my $overlay = SDL::Overlay->new( 100, 100, SDL_YV12_OVERLAY, $display); DESCRIPTION
A "SDL_Overlay" allows for video rendering on an "SDL_Surface" which is a display. The term 'overlay' is a misnomer since, unless the overlay is created in hardware, the contents for the display surface underneath the area where the overlay is shown will be overwritten when the overlay is displayed. METHODS
new ( $width, $height, $YUV_flag, $display) The constructor creates a SDL::Overlay of the specified width, height and format (see "YUV_Flags" list below of available formats), for the provided display. Note the 'display' argument needs to actually be the surface created by "SDL::Video::SetVideoMode" otherwise this function will segfault. my $overlay = SDL::Overlay->new( $width, $height, $YUV_flag, $display ); YUV_Flags More information on YUV formats can be found at <http://www.fourcc.org/indexyuv.htm> . o SDL_YV12_OVERLAY 0x32315659 /* Planar mode: Y + V + U */ o SDL_IYUV_OVERLAY 0x56555949 /* Planar mode: Y + U + V */ o SDL_YUY2_OVERLAY 0x32595559 /* Packed mode: Y0+U0+Y1+V0 */ o SDL_UYVY_OVERLAY 0x59565955 /* Packed mode: U0+Y0+V0+Y1 */ o SDL_YVYU_OVERLAY 0x55595659 /* Packed mode: Y0+V0+Y1+U0 */ format Overlay format (see YUV_Flags) w, h Width and height of overlay planes Number of planes in the overlay. Usually either 1 or 3 pitches An array of pitches, one for each plane. Pitch is the length of a row in bytes. pixels As of release 2.3 direct right to overlay is disable. An array of pointers to the data of each plane. The overlay should be locked before these pointers are used. see SDL::Video::lock_YUV_overlay, SDL::Video::unload_YUV_overlay hw_overlay This will be set to 1 if the overlay is hardware accelerated. AUTHORS
See "AUTHORS" in SDL. perl v5.14.2 2012-05-28 pods::SDL::Overlay(3pm)
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