/* >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> vmode - XF86Config Monitor Video Mode Generator, v.0.1 Introduction If you've hacked on an Xconfig file to get your display working in X386 or XFree86, then you probably know what this program is for. It generates an Xconfig (or XF86Config) mode definition for your display. It's based entirely on "The Hitchhiker's Guide to X386/XFree86 Video Timing (or, Tweaking your Monitor for Fun and Profit)" by Eric Raymond, et. al. My copy was in /var/X11R6/lib/doc/VideoModes.doc (slakware 2.02) or something like that. I would recommend reading it if you're interested in what this program does. Getting the Dot Clocks Before you use this program, it's best to know what dot clocks are available from your video card. Fortunately, the X server should be able to probe your card to get these for you. You can use one of the sample XF86Config files (e.g. XF86Config.eg), but make sure you comment out all of the "Clocks" lines. Run "X -probeonly" 10 to 20 times and write down the clock frequencies that occur most frequently for each column of clock output. Horizontal Scan Frequency and Video Bandwidth If you have a manual for your video display, look in the specifications section. Horizontal scan frequency is given as a range for multisync displays. Write down the largest number in the range. Also note the video bandwidth for your display. Refresh Rate This is how many times per second your screen is refreshed. If the value is too low, your screen will appear to flicker (and probably give you a headache). The VESA ergonomic standard is 72 Hz. Most people can live with 60 Hz. It's best to stay somewhere between these two values. Compiling vmode To compile vmode, use a command line like: cc -o vmode vmode.c -lm Running vomde Now that you have an executable and you understand the command line arguments, here's the command synopsis: vmode [dot clock (Mhz)] If You Know max horizontal scan freq: Leave off the dot clock argument for your first run of vmode. The program will calculate a dot clock to you get started. Pick the dot clock from the list you made above that is closest to the value vmode generated (must NOT be higher than your display's bandwidth). Run the program again with the dot clock you picked. If You Don't: Pick a high value for max horizontal scan freq. (like 200). Run vmode with dot clocks from the list you made above. It's best to try numbers from the middle of the range first. The Output Put the output in your XF86Config file under the "Monitor" Section. For example: Section "Monitor" Identifier "Generic Monitor" VendorName "Unknown" ModelName "Unknown" Bandwidth 30 HorizSync 30-37 VertRefresh 50-90 Mode "712x534" # Generated by vmode 60 37 30 DotClock 30.0 HTimings 712 744 864 896 VTimings 534 536 541 561 EndMode # HSF = 33.5 khz # VSF = 59.7 Hz EndSection My favorite way to do this is to edit XF86Config with vi(1), move the cursor down to the VertRefresh line (for example), and type: :r !vmode ... Tweaking Given favorable circumstances, vmode can usually generate a mode that will be stable if not optimal. You may have to try a few runs to get something that works, however. From there, try a program called vgaset to fine tune your screen. The more data you have on your display, the closer vmode can come to an optimal setting. If, for example, your know your display's horizontal and vertical sync pulse durations and its horizontal and vertical guard times, you can compile them into vmode with a compile line like: cc -DHSP=0.0000031 -DHGT=29.0 -DVSP=0.000091 -DVGT=0.0 -o vmode ... Author: dsnyder@mindspring.com (David C. Snyder) 11/10/94 <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< */ #include #include #ifndef HSP #define HSP 0.0000037 /* Horizontal Sync Pulse Duration in seconds */ #endif #ifndef HGT #define HGT 32.0 /* Horizontal Guard Time in clock ticks */ #endif #ifndef VSP #define VSP 0.00015 /* Vertical Sync Pulse Duration in seconds */ #endif #ifndef VGT #define VGT 2.0 /* Vertical Guard Time in clock ticks */ #endif main(int argc, char *argv[]) { double hsfm, /* max horizontal sync frequency */ hsf, /* horizontal sync frequency */ rr, /* refresh rate */ dcf, /* driving clock frequency (or dot clock) */ hfl, /* horizontal frame length */ hr, /* horizontal screen resolution */ hdif, /* a temporary variable */ vr, /* vertical screen resolution */ vfl, /* vertical frame length */ mem, /* minimum video memory required for hr & vr */ hspt, /* horizontal sync pulse time (duration) */ hsp, /* horizontal sync pulse width */ hgt, /* horizontal guard time */ vspt, /* vertical sync pulse time (duration) */ vsp, /* vertical sync pulse width */ vgt, /* vertical guard time */ sh1, /* start tick of horizontal sync pulse */ sh2, /* end tick of horizontal sync pulse */ sv1, /* start tick of vertical sync pulse */ sv2; /* end tick of vertical sync pulse */ if (argc < 3) { fprintf(stderr, "Usage: vmode " " " "[dot clock (Mhz)]\n"); exit(1); } sscanf(argv[1], "%lf", &rr); sscanf(argv[2], "%lf", &hsfm); hsfm *= 1000.0; if (argc > 3) { sscanf(argv[3], "%lf", &dcf); dcf *= 1000000.0; hsf = sqrt(dcf*rr*1.05*0.75/1.25); hsf = (hsf < hsfm) ? hsf : hsfm; } else { hsf = hsfm; dcf = 1.25*hsf*hsf/rr/1.05/0.75; } dcf = floor(dcf/100000.0+0.5)*100000.0; hspt = HSP; vspt = VSP; hgt = HGT; vgt = VGT; hfl = ceil(dcf/hsf/8.0) * 8.0; hsp = floor(dcf*hspt/8.0+0.5) * 8.0; hr = floor(dcf/hsf*0.8/8.0+0.5) * 8.0; hdif = (hsp+2.0*hgt)-(hfl-hr); if (hdif > 0.0) /* not enough space between hfl and hr for hsp and 2 hgt's */ { hfl = floor((hfl+hdif/2.0)/8.0+0.5) * 8.0; hsf = dcf/hfl; hr = floor((hr-hdif/2.0)/8.0+0.5) *8.0; } vr = 0.75*hr; vfl = floor(1.05*vr+0.5); mem = ceil(hr*vr/1024.0); vsp = floor(vspt*dcf/hfl+0.5); sh1 = floor(hr+hgt+0.5); sh2 = floor(hfl-hgt+0.5); sv1 = floor(vr+vgt+0.5); sv2 = floor(vr+vgt+vsp+0.5); printf(" Mode \"%.0lfx%.0lf\"\n", hr, vr); printf(" DotClock %.1lf\n", dcf/1000000.0); printf(" HTimings %.0lf %4.0lf %4.0lf %4.0lf\n",hr,sh1,sh2,hfl); printf(" VTimings %.0lf %4.0lf %4.0lf %4.0lf\n",vr,sv1,sv2,vfl); printf(" EndMode\n"); printf(" # HSF = %.1lf khz\n", dcf/hfl/1000.0); printf(" # VSF = %.1lf Hz\n", dcf/hfl/vfl); return (0); }