Dosbox-x: fullscreen=true broken in GNOME

[BPaden]

When I try to run dosbox-x with fullscreen=true, I get this weirdness you see in the photo. Forgive the cellphone photo — I couldn't figure out how to capture it with a screenshot.

This can be worked around by hitting alt-enter twice, or by simply using fullscreen=false and using alt-enter to get back into fullscreen.

Probably this is an issue with using SDL 1.x and GNOME. I believe the preferred way of doing fullscreen these days is to just use the native resolution of the display and scale the framebuffer to the desired size, which I think is a feature of SDL 2 only.

# This is the configuration file for DOSBox SVN. (Please use the latest version of DOSBox)
# Lines starting with a # are comment lines and are ignored by DOSBox.
# They are used to (briefly) document the effect of each option.

[sdl]
#       fullscreen: Start dosbox directly in fullscreen. (Press ALT-Enter to go back)
#       fulldouble: Use double buffering in fullscreen. It can reduce screen flickering, but it can also result in a slow DOSBox.
#   fullresolution: What resolution to use for fullscreen: original, desktop or a fixed size (e.g. 1024x768).
#                     Using your monitor's native resolution with aspect=true might give the best results.
#                     If you end up with small window on a large screen, try an output different from surface.
# windowresolution: Scale the window to this size IF the output device supports hardware scaling.
#                     (output=surface does not!)
#           output: What video system to use for output.
#                   Possible values: surface, overlay, opengl, openglnb.
#         autolock: Mouse will automatically lock, if you click on the screen. (Press CTRL-F10 to unlock)
#      sensitivity: Mouse sensitivity.
#      waitonerror: Wait before closing the console if dosbox has an error.
#         priority: Priority levels for dosbox. Second entry behind the comma is for when dosbox is not focused/minimized.
#                     pause is only valid for the second entry.
#                   Possible values: lowest, lower, normal, higher, highest, pause.
#       mapperfile: File used to load/save the key/event mappings from. Resetmapper only works with the default value.
#     usescancodes: Avoid usage of symkeys, might not work on all operating systems.

fullscreen=true
fulldouble=false
fullresolution=original
windowresolution=original
output=surface
autolock=true
sensitivity=100
waitonerror=true
priority=higher,normal
mapperfile=
usescancodes=true

[dosbox]
# language: Select another language file.
#  machine: The type of machine DOSBox tries to emulate.
#           Possible values: hercules, cga, tandy, pcjr, ega, vgaonly, svga_s3, svga_et3000, svga_et4000, svga_paradise, vesa_nolfb, vesa_oldvbe.
# captures: Directory where things like wave, midi, screenshot get captured.
#  memsize: Amount of memory DOSBox has in megabytes.
#             This value is best left at its default to avoid problems with some games,
#             though few games might require a higher value.
#             There is generally no speed advantage when raising this value.

language=
machine=svga_s3
captures=/home/aaron
memsize=16

[render]
# frameskip: How many frames DOSBox skips before drawing one.
#    aspect: Do aspect correction, if your output method doesn't support scaling this can slow things down!.
#    scaler: Scaler used to enlarge/enhance low resolution modes. If 'forced' is appended,
#            then the scaler will be used even if the result might not be desired.
#            Possible values: none, normal2x, normal3x, advmame2x, advmame3x, advinterp2x, advinterp3x, hq2x, hq3x, 2xsai, super2xsai, supereagle, tv2x, tv3x, rgb2x, rgb3x, scan2x, scan3x.

frameskip=0
aspect=true
scaler=none

[cpu]
#      core: CPU Core used in emulation. auto will switch to dynamic if available and
#            appropriate.
#            Possible values: auto, dynamic, normal, simple.
#   cputype: CPU Type used in emulation. auto is the fastest choice.
#            Possible values: auto, 386, 386_slow, 486_slow, pentium_slow, 386_prefetch.
#    cycles: Amount of instructions DOSBox tries to emulate each millisecond.
#            Setting this value too high results in sound dropouts and lags.
#            Cycles can be set in 3 ways:
#              'auto'          tries to guess what a game needs.
#                              It usually works, but can fail for certain games.
#              'fixed #number' will set a fixed amount of cycles. This is what you usually
#                              need if 'auto' fails (Example: fixed 4000).
#              'max'           will allocate as much cycles as your computer is able to
#                              handle.
#            Possible values: auto, fixed, max.
#   cycleup: Amount of cycles to decrease/increase with keycombos.(CTRL-F11/CTRL-F12)
# cycledown: Setting it lower than 100 will be a percentage.

core=auto
cputype=auto
cycles=auto
cycleup=10
cycledown=20

[mixer]
#   nosound: Enable silent mode, sound is still emulated though.
#      rate: Mixer sample rate, setting any device's rate higher than this will probably lower their sound quality.
#            Possible values: 44100, 48000, 32000, 22050, 16000, 11025, 8000, 49716.
# blocksize: Mixer block size, larger blocks might help sound stuttering but sound will also be more lagged.
#            Possible values: 1024, 2048, 4096, 8192, 512, 256.
# prebuffer: How many milliseconds of data to keep on top of the blocksize.

nosound=false
rate=44100
blocksize=1024
prebuffer=20

[midi]
#     mpu401: Type of MPU-401 to emulate.
#             Possible values: intelligent, uart, none.
# mididevice: Device that will receive the MIDI data from MPU-401.
#             Possible values: default, win32, alsa, oss, coreaudio, coremidi, none.
# midiconfig: Special configuration options for the device driver. This is usually the id of the device you want to use.
#               or in the case of coreaudio, you can specify a soundfont here.
#               When using a Roland MT-32 rev. 0 as midi output device, some games may require a delay in order to prevent 'buffer overflow' issues.
#               In that case, add 'delaysysex', for example: midiconfig=2 delaysysex
#               See the README/Manual for more details.

mpu401=intelligent
mididevice=default
midiconfig=128:0

[sblaster]
#  sbtype: Type of Soundblaster to emulate. gb is Gameblaster.
#          Possible values: sb1, sb2, sbpro1, sbpro2, sb16, gb, none.
#  sbbase: The IO address of the soundblaster.
#          Possible values: 220, 240, 260, 280, 2a0, 2c0, 2e0, 300.
#     irq: The IRQ number of the soundblaster.
#          Possible values: 7, 5, 3, 9, 10, 11, 12.
#     dma: The DMA number of the soundblaster.
#          Possible values: 1, 5, 0, 3, 6, 7.
#    hdma: The High DMA number of the soundblaster.
#          Possible values: 1, 5, 0, 3, 6, 7.
# sbmixer: Allow the soundblaster mixer to modify the DOSBox mixer.
# oplmode: Type of OPL emulation. On 'auto' the mode is determined by sblaster type. All OPL modes are Adlib-compatible, except for 'cms'.
#          Possible values: auto, cms, opl2, dualopl2, opl3, opl3gold, none.
#  oplemu: Provider for the OPL emulation. compat might provide better quality (see oplrate as well).
#          Possible values: default, compat, fast.
# oplrate: Sample rate of OPL music emulation. Use 49716 for highest quality (set the mixer rate accordingly).
#          Possible values: 44100, 49716, 48000, 32000, 22050, 16000, 11025, 8000.

sbtype=sb16
sbbase=220
irq=7
dma=1
hdma=5
sbmixer=true
oplmode=auto
oplemu=default
oplrate=44100

[gus]
#      gus: Enable the Gravis Ultrasound emulation.
#  gusrate: Sample rate of Ultrasound emulation.
#           Possible values: 44100, 48000, 32000, 22050, 16000, 11025, 8000, 49716.
#  gusbase: The IO base address of the Gravis Ultrasound.
#           Possible values: 240, 220, 260, 280, 2a0, 2c0, 2e0, 300.
#   gusirq: The IRQ number of the Gravis Ultrasound.
#           Possible values: 5, 3, 7, 9, 10, 11, 12.
#   gusdma: The DMA channel of the Gravis Ultrasound.
#           Possible values: 3, 0, 1, 5, 6, 7.
# ultradir: Path to Ultrasound directory. In this directory
#           there should be a MIDI directory that contains
#           the patch files for GUS playback. Patch sets used
#           with Timidity should work fine.

gus=false
gusrate=44100
gusbase=240
gusirq=5
gusdma=3
ultradir=C:\ULTRASND

[speaker]
# pcspeaker: Enable PC-Speaker emulation.
#    pcrate: Sample rate of the PC-Speaker sound generation.
#            Possible values: 44100, 48000, 32000, 22050, 16000, 11025, 8000, 49716.
#     tandy: Enable Tandy Sound System emulation. For 'auto', emulation is present only if machine is set to 'tandy'.
#            Possible values: auto, on, off.
# tandyrate: Sample rate of the Tandy 3-Voice generation.
#            Possible values: 44100, 48000, 32000, 22050, 16000, 11025, 8000, 49716.
#    disney: Enable Disney Sound Source emulation. (Covox Voice Master and Speech Thing compatible).

pcspeaker=true
pcrate=44100
tandy=auto
tandyrate=44100
disney=true

[joystick]
# joysticktype: Type of joystick to emulate: auto (default), none,
#               2axis (supports two joysticks),
#               4axis (supports one joystick, first joystick used),
#               4axis_2 (supports one joystick, second joystick used),
#               fcs (Thrustmaster), ch (CH Flightstick).
#               none disables joystick emulation.
#               auto chooses emulation depending on real joystick(s).
#               (Remember to reset dosbox's mapperfile if you saved it earlier)
#               Possible values: auto, 2axis, 4axis, 4axis_2, fcs, ch, none.
#        timed: enable timed intervals for axis. Experiment with this option, if your joystick drifts (away).
#     autofire: continuously fires as long as you keep the button pressed.
#       swap34: swap the 3rd and the 4th axis. can be useful for certain joysticks.
#   buttonwrap: enable button wrapping at the number of emulated buttons.

joysticktype=auto
timed=true
autofire=false
swap34=false
buttonwrap=false

[serial]
# serial1: set type of device connected to com port.
#          Can be disabled, dummy, modem, nullmodem, directserial.
#          Additional parameters must be in the same line in the form of
#          parameter:value. Parameter for all types is irq (optional).
#          for directserial: realport (required), rxdelay (optional).
#                           (realport:COM1 realport:ttyS0).
#          for modem: listenport (optional).
#          for nullmodem: server, rxdelay, txdelay, telnet, usedtr,
#                         transparent, port, inhsocket (all optional).
#          Example: serial1=modem listenport:5000
#          Possible values: dummy, disabled, modem, nullmodem, directserial.
# serial2: see serial1
#          Possible values: dummy, disabled, modem, nullmodem, directserial.
# serial3: see serial1
#          Possible values: dummy, disabled, modem, nullmodem, directserial.
# serial4: see serial1
#          Possible values: dummy, disabled, modem, nullmodem, directserial.

serial1=dummy
serial2=dummy
serial3=disabled
serial4=disabled

[dos]
#            xms: Enable XMS support.
#            ems: Enable EMS support. The default (=true) provides the best
#                 compatibility but certain applications may run better with
#                 other choices, or require EMS support to be disabled (=false)
#                 to work at all.
#                 Possible values: true, emsboard, emm386, false.
#            umb: Enable UMB support.
# keyboardlayout: Language code of the keyboard layout (or none).

xms=true
ems=true
umb=true
keyboardlayout=auto

[ipx]
# ipx: Enable ipx over UDP/IP emulation.

ipx=false

[autoexec]
# Lines in this section will be run at startup.
# You can put your MOUNT lines here.

[BPaden]

Ah, this seems to be a problem specifically fullresolution=original, which I typically don't use anyway (because I'm not sure why you ever would).

[joncampbell123]

@BPaden Should I close this?

[mgiuca]

Ah, this seems to be a problem specifically fullresolution=original, which I typically don't use anyway (because I'm not sure why you ever would).

Using sdl.fullresolution=original, in DOSBox, physically sets your monitor's resolution to the original, if supported. I tried it in Linux and Windows 10, using DOSBox 0.74, and if I open a 640x480 application, it literally tells my monitor to go to 640x480 mode (if I press the menu on my monitor, it says it's in 640x480 resolution).

sdl.fullresolution=original doesn't work in DOSBox-X (also tried in both Linux and Windows 10); it just makes the game window tiny in the center of the screen. You have to use sdl.fullresolution=desktop, sdl.output=opengl, render.aspect=true, to get the game to show in full screen, with the monitor set to my desktop resolution (1920x1080) and using the GPU to scale, instead of the monitor.

It depends on the monitor, but I find it much sharper with my monitor to use sdl.fullresolution=original in DOSBox than GPU scaling in DOSBox-X. The pixels aren't blurred; they look like real pixels. I've also tried using sdl.output=openglnb but then the pixels are slightly different sizes because 1080 is not an exact multiple of 480 and it looks horrible. It's very hard to illustrate this because I can't take a screenshot of the output of my monitor scaling the 640x480 version.

Not being able to use sdl.fullresolution=original is making me want to go back to DOSBox 0.74.

[mgiuca]

I did some digging in sdlmain.cpp. So far I haven't found anything conclusive, but I'll post my results.

I inserted the following shim to log all the calls to SDL_SetVideoMode in sdlmain.cpp:

SDL_Surface* SDL_SetVideoMode_Wrap(int width, int height, int bpp,
                                   Bit32u flags) {
    std::string flagstring;
    if (flags & SDL_SWSURFACE)
        flagstring += "SWSURFACE | ";
    if (flags & SDL_HWSURFACE)
        flagstring += "HWSURFACE | ";
    if (flags & SDL_ASYNCBLIT)
        flagstring += "ASYNCBLIT | ";
    if (flags & SDL_ANYFORMAT)
        flagstring += "ANYFORMAT | ";
    if (flags & SDL_HWPALETTE)
        flagstring += "HWPALETTE | ";
    if (flags & SDL_DOUBLEBUF)
        flagstring += "DOUBLEBUF | ";
    if (flags & SDL_FULLSCREEN)
        flagstring += "FULLSCREEN | ";
    if (flags & SDL_OPENGL)
        flagstring += "OPENGL | ";
    if (flags & SDL_OPENGLBLIT)
        flagstring += "OPENGLBLIT | ";
    if (flags & SDL_RESIZABLE)
        flagstring += "RESIZABLE | ";
    if (flags & SDL_HWACCEL)
        flagstring += "HWACCEL | ";
    if (flags & SDL_SRCCOLORKEY)
        flagstring += "SRCCOLORKEY | ";
    if (flags & SDL_RLEACCEL)
        flagstring += "RLEACCEL | ";
    if (flags & SDL_SRCALPHA)
        flagstring += "SRCALPHA | ";
    if (flags & SDL_PREALLOC)
        flagstring += "PREALLOC | ";
    if (flagstring.size() > 0)
        flagstring = flagstring.substr(0, flagstring.size() - 3);
    else
        flagstring = "0";

    printf("SDL_SetVideoMode(%d, %d, %d, %s)\n",
        width, height, bpp, flagstring.c_str());
    return SDL_SetVideoMode(width, height, bpp, flags);
}

And did the same in DOSBox-SVN (fwiw, a very old checkout I had from 2015: 063fd41a55, but shouldn't really matter since it works properly there).

Here are the logging results. Just starting up the terminal, with aspect=true, fullscreen=true, fullresolution=original and output=surface.

DOSBox:

SDL_SetVideoMode(640, 400, 0, 0)
SDL_SetVideoMode(640, 480, 32, HWPALETTE | FULLSCREEN)
SDL_SetVideoMode(640, 480, 32, 0)

DOSBox-X (d955cf92):

SDL_SetVideoMode(640, 480, 32, HWSURFACE | HWPALETTE | FULLSCREEN)
SDL_SetVideoMode(720, 537, 32, HWPALETTE | FULLSCREEN)
SDL_SetVideoMode(720, 554, 32, ANYFORMAT | RESIZABLE)

OK, so it's asking for a fairly non-standard resolution and also not fullscreen. That's dubious. I'm not sure which of these logs are happening at startup and which at shutdown, but I suspect the 2nd entry is what is used during the terminal session.

But the head-scratcher is when you actually go into a game (I'm using Warcraft: Orcs & Humans, which is 320x200 VGA). Starting up the emulator in full screen, starting the game, then quitting the game and exiting:

DOSBox:

SDL_SetVideoMode(640, 400, 0, 0)
SDL_SetVideoMode(640, 480, 32, HWPALETTE | FULLSCREEN)
SDL_SetVideoMode(640, 480, 32, 0)

(No change from the terminal-only version.)

DOSBox-X:

SDL_SetVideoMode(640, 480, 32, HWSURFACE | HWPALETTE | FULLSCREEN)
SDL_SetVideoMode(720, 537, 32, HWPALETTE | FULLSCREEN)
SDL_SetVideoMode(640, 480, 32, HWPALETTE | FULLSCREEN)
SDL_SetVideoMode(720, 537, 32, HWPALETTE | FULLSCREEN)
SDL_SetVideoMode(720, 554, 32, ANYFORMAT | RESIZABLE)

When I switch into the 320x200 mode, DOSBox-X requests 640x480x32 mode, with HWPALETTE and FULLSCREEN --- exactly the same mode that DOSBox original is requesting. But DOSBox switches into true 640x480 whereas DOSBox-X stays at 1920x1080, drawing the game graphics to the center of the screen with garbage (my desktop but not receiving paints) over the rest of the screen.

I believe SDL_SetVideoMode is what causes the monitor to change resolution in DOSBox. Therefore, I suspect that calling SDL_SetVideoMode in the non-standard 720x537 resolution earlier on is causing it to behave weirdly when called with the standard 640x480 resolution.

(Oh, I realised that using aspect=true applies weird stretching for a 320x200 game. Running it again with aspect=false produces different calls to SDL_SetVideoMode but the exact same behaviour is seen on both versions.)

All of this is on Linux / Ubuntu.