Video Cards :: Video Memory Intercept and Redirect Post: 302482780

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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

12-22-2010

Registered User

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.

ciNG

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LEARN ABOUT DEBIAN

guvcview

GUVCVIEW(1)						      General Commands Manual						       GUVCVIEW(1)

NAME

       guvcview - GTK+ base UVC Viewer

SYNOPSIS

       guvcview

DESCRIPTION

       Guvcview  is  a	simple	GTK+  interface for capturing and viewing video from devices supported by the Linux UVC driver.  It fully supports
       video4linux2 so it should work with any driver that supports this API, including the gspca driver.

USAGE

       guvcview [options...]

OPTION

	 -?, --help		      Print help options
	 --help-all		      Print all help options
	 --help-gtk		      Print GTK+ options
	 --version		      Print version number

       Aplication options:
	 -v, --verbose		      Prints a lot of debug information
	 -d, --device=VIDEO_DEVICE    Video Device [default: /dev/video0]
	 -a, --add_ctrls	      Exits after adding dynamic controls to the uvc driver (needs root/sudo)
	 -o, --control_only	      Don't stream video (image controls only)
	 -r, --capture_method=[1|2]   Capture method (1-mmap (default) 2-read)
	 -g, --config=FILENAME	      Configuration File
	 -w, --hwd_acel=[1|0]	      Hardware accelaration:
						 (enable(1) | disable(0))
	 -f, --format=FORMAT	      Video input format:
	    mjpg | jpeg | yuyv | yvyu | uyvy | yyuv | yu12 | yv12 | nv12 |
	    nv21 | nv16 | nv61 | y11p | grey | s501 | s505 | s508 | gbrg |
	    grbg | ba81 | rggb | bgr3 | rgb3 |
	 -s, --size=WIDTHxHEIGHT      Resolution, default: 640x480
	 -i, --image=FILENAME	      Image File
	 -c, --cap_time=TIME	      Time elapsed between image captures
	 -m, --npics=NUMPIC	      Number of images to capture
	 -n, --video=FILENAME	      Video File (capture from start)
	 -t, --vid_time=TIME	      Video duration (in seconds)
	 --exit_on_close	      Exits guvcview after closing video
	 -j, --skip=N_FRAMES	      Number of inital frames to skip
	 -p, --show_fps=[1|0]	      Print FPS on video Window:
						 (enable(1) | disable(0))
	 -l, --profile=FILENAME       Load profile

AUTHOR

       This manual page was written by Paulo Assis <pj.assis@gmail.com>, for the Debian GNU/Linux system (but may be used by others).

								     Aug 2009							       GUVCVIEW(1)