Hello tableteers,
I've done some initial experiments hacking my N800/OS2008 and ran into a
couple of issues:
When using the supplied SDL library for doing timer-based frame
rendering, there seems to be
- heavy tearing
- significant overhead due to X server
(rendering pipe is : SDL - X - Framebuffer)
[Note: yes, I'm aware that doing full screen blits is evil on the N800
due to limited framebuffer - video RAM bus bandwidth.]
Q: Is this expected behaviour? What could I do about the tearing? What
about the Xomap overhead?
==
I've read a lot of bits on the web 'bout mplayer, vsync, omapfb etc.
and tried to assemble a minimal example of using direct framebuffer
access for gfx output.
Q: I can't get the tearing away (only fixed at certain line positions).
What am I doing wrong?
Q: Also, frame rate is sluggish, though CPU load is much lower than
SDL/X. Ok, my FB example is not threaded like the SDL timer example ..
is that the reason for framerate even 15/s?
Q: btw - how can I shutdown Maemo Launcher/Hildon/Matchbox/Xomap?
Whenever I do one of
/etc/init.d/maemo-launcher stop
/etc/init.d/x-server stop
the device will automatically reboot.
==
I wondered if there would be any plans to make SDL run directly on
framebuffer .. if not, I'd maybe give it a try.
Q: Where can I find the sources to the OS2008 SDL?
Thx and cheers,
tgo
=
SDL Test
=== Makefile:
##
## produce ARM11 target optimized code
## use hardware FP, but use soft FP ABI for math lib
##
OPT_FLAGS = -O3 -fomit-frame-pointer -mcpu=arm1136j-s -mfpu=vfp
-mfloat-abi=softfp
##
## SDL compile/link flags
##
SDL_FLAGS = `sdl-config --cflags` `sdl-config --libs`
##
## compiler command
##
CC = gcc -Wall $(OPT_FLAGS) $(SDL_FLAGS)
all: sdl_timer
sdl_timer: sdl_timer.c
$(CC) sdl_timer.c -o sdl_timer
=== Source:
//
// minimal timer based SDL fullscreen test for N800
//
// the test seems to indicate 2 problems:
//
// 1) heavy tearing
// 2) significant overhead due to X server (rendering pipe is : SDL -
X - Framebuffer)
//
/*
Mem: 90376K used, 36452K free, 0K shrd, 716K buff, 42956K cached
Load average: 1.01 0.64 0.44
PID USER STATUS VSZ PPID %CPU %MEM COMMAND
756 root SW11368 338 21.8 8.9 Xomap
1831 root SW 12532 1365 7.3 9.8 sdl_timer
1815 root RW 1960 1799 3.0 1.5 top
78 root SW0 6 2.7 0.0 OMAP McSPI/0
1032 user SW32052 957 2.1 25.2 maemo-launcher
376 root SW0 6 1.6 0.0 cx3110x
...
*/
#include stdlib.h
#include string.h
#include unistd.h
#include SDL.h
#define HRES 800
#define VRES 480
#define BPP 16
//
// frame render callback
//
Uint32 renderFrame (Uint32 interval, void *param)
{
static int col = 0;
// get screen surface from parameter
SDL_Surface *screen = (SDL_Surface*) param;
// lock surface if needed
if (SDL_MUSTLOCK(screen))
{
if (SDL_LockSurface(screen) 0)
{
fprintf (stderr, unable to lock surface\n);
exit(1);
}
}
// render whole frame in single color
memset(screen-pixels, ++col, HRES * BPP / 8 * VRES);
// unlock surface if needed
if (SDL_MUSTLOCK(screen))
{
SDL_UnlockSurface(screen);
}
// update whole screen
SDL_UpdateRect(screen, 0, 0, HRES, VRES);
// continue firing
return interval;
}
int main (int argc, char** argv)
{
// initialize SDL
if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_TIMER) 0)
{
fprintf (stderr, unable to initialize SDL : %s\n, SDL_GetError());
exit(1);
}
// register SDL cleanup
atexit (SDL_Quit);
// set mouse pointer invisible
SDL_ShowCursor (SDL_DISABLE);
// set video mode to fullscreen
SDL_Surface *screen = SDL_SetVideoMode(HRES, VRES, BPP, SDL_SWSURFACE
| SDL_FULLSCREEN);
if (screen == NULL)
{
fprintf (stderr, unable to initialize video : %s\n, SDL_GetError());
exit(1);
}
// setup frame renderer at rate 17 frames/s (every 60ms)
SDL_TimerID tid = SDL_AddTimer (60,
(SDL_NewTimerCallback) renderFrame,
screen);
// run for 60 secs
sleep (60);
// shutdown frame renderer
SDL_bool ret = SDL_RemoveTimer (tid);
if (!ret)
{
fprintf (stderr, could not shutdown timer : %s\n, SDL_GetError());
exit(1);
}
// finished
return 0;
}
===
=
Framebuffer Test
=== Makefile:
##
## produce ARM11 target optimized code
## use hardware FP, but use soft FP ABI for math lib
##
OPT_FLAGS = -O3 -fomit-frame-pointer -mcpu=arm1136j-s -mfpu=vfp
-mfloat-abi=softfp
##
## compiler command
##
CC = gcc -Wall $(OPT_FLAGS) -lX11
all: fb_minimal
fb_minimal: fb_minimal.c
$(CC) fb_minimal.c -o fb_minimal
=== Source:
//
//
// Test for direct framebuffer graphics bypassing X. (tested on N800)
//
