Programming the CG2
Mike Muuss
they don't put out bi-polar NTSC, which results in a grey-level shift
that is quite objectionable, and the internal sync generator is so awful
as to be unusable without a time-base corrector.
Here is a fragment of code (from BRL-CAD libfb/if_4d.c) that shows how
I run ours.
I understand that the CG3 is vastly improved over the CG2, but ours has
not yet been delivered.
Best,
-Mike
/*
* Take inventory of the hardware
*/
while( (inv = getinvent()) != (inventory_t *)0 ) {
if( inv->class != INV_GRAPHICS ) continue;
switch( inv->type ) {
case INV_GMDEV:
SGI(ifp)->mi_is_gt = 1;
break;
}
}
endinvent(); /* frees internal inventory memory */
if( (ifp->if_mode & MODE_8MASK) == MODE_8NOGT ) {
SGI(ifp)->mi_is_gt = 0;
}
/*Note:---->*/
if( (ifp->if_mode & MODE_5MASK) == MODE_5GENLOCK ) {
/* NTSC, see below */
ifp->if_width = ifp->if_max_width = XMAX170+1; /* 646 */
ifp->if_height = ifp->if_max_height = YMAX170+1; /* 485 */
}
if( width <= 0 )
width = ifp->if_width;
if( height <= 0 )
height = ifp->if_height;
if ( width > ifp->if_max_width )
width = ifp->if_max_width;
if ( height > ifp->if_max_height)
height = ifp->if_max_height;
ifp->if_width = width;
ifp->if_height = height;
blanktime(0);
foreground(); /* Direct focus here, don't detach */
if( (ifp->if_mode & MODE_5MASK) == MODE_5GENLOCK ) {
/*Note:---->*/
prefposition( 0, XMAX170, 0, YMAX170 );
SGI(ifp)->mi_curs_on = 0; /* cursoff() happens below */
} else if( (ifp->if_mode & MODE_3MASK) == MODE_3WINDOW ) {
if( sgi_nwindows == 0 ) {
prefposition( WIN_L, WIN_R, WIN_B, WIN_T );
} else {
prefsize( (long)width, (long)height );
}
SGI(ifp)->mi_curs_on = 1; /* Mex usually has it on */
} else {
/* MODE_3MASK == MODE_3FULLSCR */
prefposition( 0, XMAXSCREEN, 0, YMAXSCREEN );
SGI(ifp)->mi_curs_on = 0; /* cursoff() happens below */
}
/*
* This is where the window constraints specified above
* are bound to a new window. The return code is
* the "graphics id" that identifies this window.
* winset(gr_id) is used to select a window for drawing in.
*/
if( (ifp->if_fd = winopen( "Frame buffer" )) == -1 ) {
fb_log( "winopen() failed, no more windows available.\n" );
return(-1);
}
sgi_nwindows++; /* track # of simultaneous windows */
/* Establish operating mode (Hz, GENLOCK).
* The assumption is that the device is always in the
* "normal" mode to start with. The mode will only
* be saved and restored when 30Hz operation is specified;
* on GENLOCK operation, valid NTSC sync pulses must be present
* for downstream equipment; user should run "Set60" when done.
*/
if( (ifp->if_mode & MODE_4MASK) == MODE_4HZ30 ) {
SGI(ifp)->mi_der1 = getvideo(DE_R1);
setvideo( DE_R1, DER1_30HZ|DER1_UNBLANK); /* 4-wire RS-343 */
} else if( (ifp->if_mode & MODE_5MASK) == MODE_5GENLOCK ) {
/*Note:---->*/
SGI(ifp)->mi_der1 = getvideo(DE_R1);
if( (SGI(ifp)->mi_der1 & DER1_VMASK) == DER1_170 ) {
/*
* Current mode is DE3 board internal NTSC sync.
* Doing a setmonitor(NTSC) again will cause the
* sync generator to drop out for a moment.
* So, in this case, do nothing.
*/
} else if( getvideo(CG_MODE) != -1 ) {
/*
* Optional CG2 GENLOCK board is installed.
*
* Mode 2: Internal sync generator is used.
*
* Note that the stability of the sync generator
* on the GENLOCK board is *worse* than the sync
* generator on the regular DE3 board. The GENLOCK
* version "twitches" every second or so.
*
* Mode 3: Output is locked to incoming
* NTSC composite video picture
* for sync and chroma (on "REM IN" connector).
* Color subcarrier is phase and amplitude locked to
* incomming color burst.
* The blue LSB has no effect on video overlay.
*
* Note that the generated composite NTSC output
* (on "VID OUT" connector) is often a problem,
* since it has a DC offset of +0.3V to the base
* of the sync pulse, while other studio eqiupment
* often expects the blanking level to be at
* exactly 0.0V, with sync at -0.3V.
* In this case, the black levels are ruined.
* Also, the inboard encoder chip isn't very good.
* Therefore, it is necessary to use an outboard
* RS-170 to NTSC encoder to get useful results.
*/
if( (ifp->if_mode & MODE_6MASK) == MODE_6EXTSYNC ) {
/* external sync via GENLOCK board REM IN */
setvideo(CG_MODE, CG2_M_MODE3);
setvideo(DE_R1, DER1_G_170|DER1_UNBLANK );
} else {
/* internal sync */
#ifdef GENLOCK_SYNC
/* GENLOCK sync, found to be highly unstable */
setvideo(CG_MODE, CG2_M_MODE2);
setvideo(DE_R1, DER1_G_170|DER1_UNBLANK );
#else
/* Just use DE3 sync generator.
* For this case, GENLOCK board does nothing!
* Equiv to setmonitor(NTSC);
*/
setvideo(DE_R1, DER1_170|DER1_UNBLANK);
#endif
}
} else {
/*
* No genlock board is installed, produce RS-170
* video at NTSC rates with separate sync,
* and hope that they have an outboard NTSC
* encoder device. Equiv to setmonitor(NTSC);
*/
setvideo(DE_R1, DER1_170|DER1_UNBLANK);
}
}