[Mplayer-cvslog] CVS: main/DOCS DGA,1.1,1.2

[Andreas Ackermann]

Update of /cvsroot/mplayer/main/DOCS
In directory usw-pr-cvs1:/tmp/cvs-serv26232

Modified Files:
	DGA 
Log Message:
- some more introductionary words; no real flesh yet however ;-( (got to go to bed)
cvs: ----------------------------------------------------------------------


Index: DGA
===================================================================
RCS file: /cvsroot/mplayer/main/DOCS/DGA,v
retrieving revision 1.1
retrieving revision 1.2
diff -C2 -r1.1 -r1.2
*** DGA	2001/05/17 22:01:50	1.1
--- DGA	2001/05/17 23:35:51	1.2
***************
*** 5,13 ****
   1. Summary
   2. What is DGA
!  3. DGA & MPlayer
!  4. Features of DGA driver
!  5. Speed issues
!  6. Known bugs
!  7. Future work
   
   A. Some modelines
--- 5,14 ----
   1. Summary
   2. What is DGA
!  3. Resolution switching
!  4. DGA & MPlayer
!  5. Features of the DGA driver
!  6. Speed issues
!  7. Known bugs
!  8. Future work
   
   A. Some modelines
***************
*** 27,36 ****
   Technically spoken this happens by mapping the framebuffer memory into
   the memory range of your process. This is just allowed by the kernel
!  if 
  
  
!  Acki (acki at acki-netz.de, www.acki-netz.de)                  17.5.2001 
  
!  To be continued...
  
   
--- 28,124 ----
   Technically spoken this happens by mapping the framebuffer memory into
   the memory range of your process. This is just allowed by the kernel
!  if you have superuser privileges. You can get these either by logging in 
!  as root or by setting the suid bit on the mplayer excecutable.
  
+  There are two versions of DGA: DGA1 is used by XFree 3.X.X and DGA2 was 
+  introduced with XFree 4.0.1.
  
!  DGA1 just provides direct framebuffer access as described above. For 
!  switching the resolution of the video signal you have to rely on the 
!  XVidMode extension.
! 
!  DGA2 incorporated the features of XVidMode extension and also allows
!  switching the depth of the display. So you may, although basically 
!  running a 32 bit depth XServer, switch to a depth of 15 bits and vice 
!  versa. 
! 
!  However DGA has some drawbacks. It seems it is somewhat dependent on the
!  graphics chip you use and on the implementation of the XServer's video 
!  driver that controls this chip. So it does not work on every system ...
! 
! 
! 3. Resolution switching
! ~~~~~~~~~~~~~~~~~~~~~~~
!  The DGA driver allows for switching the resolution of the output signal.
!  This avoids the need for doing (slow) software scaling and at the same
!  time provides a fullscreen image. Ideally it would switch to the exact
!  resolution (except for honouring aspect ratio) of the video data, but the
!  XServer only allows switching to resolutions predefined in 
!  /etc/X11/XF86Config (/etc/X11/XF86Config-4 for XFree 4.0.X respectively).
!  Those are defined by so-called modelines and depend on the capabilites
!  of your video hardware. The XServer scans this config file on startup and
!  disables those modelines not suitable for your hardware. You can find 
!  out which modes survive with the X11 log file. It can be found at:
!  /var/log/XFree86.0.log
!  See appendix A for some sample modeline definitions.
! 
! 4. DGA & MPLayer
! ~~~~~~~~~~~~~~~~
! 
!  DGA is used in two places with MPlayer: The SDL driver can be made to make
!  use of it (-vo sdl -dga (or the like)) and within the DGA driver (-vo dga).
!  The above said is true for both; in the following sections I'll explain
!  how the DGA driver for MPlayer works.
! 
! 
! 5. Features of the DGA driver
! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
!  
!  The DGA driver is invoked by specifying -vo dga at the command line.
! 
!  ... to be continued during the next days ...
! 
! # An advantage of this method is that you are in full control of the 
! # framebuffer and can put your hand on the code that is used for copying
! # to the framebuffer. However there are two disadvantages:
!  
! # First, you control the screen - no more windowmanager functionally - just
! # the one application that uses DGA is visible.
! 
! # Second you 
!  
!  
!  
! # Do it like this (you got to be root for this):
! 
!  # chown root /usr/local/bin/mplayer
!  # chmod 750 /usr/local/bin/mplayer 
!  # chmod +s /usr/local/bin/mplayer 
!  
! # Now it works for simple users, too.
! # !!!! BUT STAY TUNED !!!!
! # This is a BIG security risk! Never do this on a server or on a computer
! # can be accessed by more people than only you because they can gain root
! # privilegies through suid root mplayer.
! # !!!! SO YOU HAVE BEEN WARNED ... !!!!
! #
! 
! A. Sample modelines
! ~~~~~~~~~~~~~~~~~~~
! Section "Modes"
!   Identifier    "Modes[0]"
!   Modeline      "712x600"  35.0   712 740 850 900   400 410 412 425
!   Modeline      "640x480"  25.175 640 664 760 800   480 491 493 525 
!   Modeline      "352x240"  15.750 352 368 416 432   240 244 246 262 Doublescan
!   # 800x600 @ 60 Hz, 37.8 kHz hsync
!   Modeline	"800x600"  40     800 840 968 1056  600 601 605 628 
!   Modeline	"352x288"  25.10  352 368 416 432   288 296 290 310
! EndSection
! 
  
!  These entries work fine with my Riva128 chip, using nv.o XServer driver
!  module.
! 
!  Acki (acki at acki-netz.de, www.acki-netz.de)                  17.5.2001 
  
   


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