I started this fork of DOSBox in order to run ReelMagic games. It would appear that no one else has done this, so I took this on as I really wanted to play the ReelMagic version of Return to Zork.
The following people have made this project a reality:
- Jon Dennis <jrdennisoss_at_gmail.com>
- Chris Guthrie <csguthrieoss_at_gmail.com>
- Joseph Whittaker <j.whittaker.us_at_ieee.org>
It is also worth mentioning Dominic Szablewski's (https://phoboslab.org) awesome
MPEG decoder library PL_MPEG was used for this, and of course this project is
built on top of work the DOSBox Team created.
The following ReelMagic games are known to work on this emulator with minimal issues:
- Return to Zork
- Lord of the Rings
- The Horde
- Entity
- Man Enough
- Dragon's Lair
- Flash Traffic
- Crime Patrol
- Crime Patrol 2 - Drug Wars
Note: Entity crashes when viewing a video message. This happens on both the emulator and on the real setup.
- The emulator does not correctly implement MPEG DMA streaming.
- MPEG video decode is only about 98% complete. There are a few glitches.
- Need to revisit architecture and approach for mixing VGA and MPEG.
- Need to re-base on to DOSBox SVN trunk.
Runs just like normal DOSBox except that it supports ReelMagic MPEG games.
There are some optional configuration parameters. See Configuration section
under the Changes to DOSBox section below for more information on this.
All that has been discovered about how the ReelMagic driver works and interacts
with things is currently documented in the RMDOS_API.md file.
Most ReelMagic MPEG file assets have been encoded in a non-standard way which
prevents them from playing in a standard MPEG media player such as VLC. In
order to get things properly working in DOSBox, I had to make a few changes
to the MPEG decoder. More information on this can be found in the
NOTES_MPEG.md file.
Game bugs that are known to exist in both this emulator AND that also happen
wich a real hardware setup are documented in the KNOWN_GAME_BUGS.md file.
This helps with not spending too much time chasing phantom issues.
Several modifications to DOSBox have been made to make this work.
A [reelmagic] configuration section has been added. It is not mandatory to
configure anything to have a working ReelMagic setup as the defaults will
enable ReelMagic emulation.
The parameters are:
enabled-- Enables/disables the ReelMagic emulator. By default this istruealwaysresident-- This forcesFMPDRV.EXEto always be loaded. By default this isfalsevgadup5hack-- Duplicate every 5th VGA line to help give output a 4:3 ratio. By default this isfalseinitialmagickey-- Provides and alternate value for the initial global "magic key" value in hex. Defaults to 40044041.magicfhack-- Use for MPEG video debugging purposes only. Seereelmagic_player.cppfor what exactly this does to the MPEG decoder.a204debug-- Controls FMPDRV.EXE function Ah subfunction 204h debug logging. Only applicable in "heavy debugging" build.a206debug-- Controls FMPDRV.EXE function Ah subfunction 206h debug logging. Only applicable in "heavy debugging" build.
For example:
[reelmagic]
enabled=true
alwaysresident=true
vgadup5hack=false
The following existing DOSBox source code files have been modified for ReelMagic emulation functionality:
include/logging.h-- AddedREELMAGIClogging type + quick fix for variable length logging argssrc/debug/debug_gui.cpp-- AddedREELMAGIClogging type.src/dosbox.cpp-- ReelMagic init hook-in and config section.src/hardware/Makefile.am-- Declared new ReelMagic *.cpp source code files
The following files have been modified to include the ReelMagic override header to redirect all VGA output from DOSBox RENDER to ReelMagic:
src/hardware/vga_dac.cppsrc/hardware/vga_draw.cppsrc/hardware/vga_other.cpp
The following new DOSBox source code files have been added for ReelMagic emulation functionality:
include/reelmagic.h-- Header file for all ReelMagic stuffinclude/vga_reelmagic_override.h-- Header file used to redirect all VGA output from DOSBox RENDER to ReelMagicsrc/hardware/reelmagic_driver.cpp-- Implements the Driver + Hardware Emulationsrc/hardware/reelmagic_pl_mpeg.cpp-- Modified version of PHOBOSLAB'sPL_MPEGlibrary found here:https://github.com/phoboslab/pl_mpegsrc/hardware/reelmagic_player.cpp-- Implements MPEG Media Decoder/Player Functionalitysrc/hardware/reelmagic_videomixer.cpp-- Intercepts the VGA output and mixes in the decoded MPEG video.
ReelMagic emulation software components are wired up as such:
|-----------------| |---------------|
| PL_MPEG | | Existing |
| Decoder Library | | DOSBox |
|-----------------| | "Render" |
^ |---------------|
| |-------------| ^
| Uses | | | Mixed VGA + MPEG
| Outputs | DOSBox | | Output Goes Here
|---------------| |-------------| Audio to | Mixer | |---------------|
| | | | --------------->| | | |
| Driver + | | MPEG | |-------------| | Video |
| Hardware | <----------> | Player(s) | | Underlay |
| Emulation | Controls | | -----------------------------------> | Mixer |
| | |-------------| Outputs | |
|---------------| Video to |---------------|
^ ^
| Can | Video Output
| Use | Intercepted By
|----------------| |---------------|
| Emulated | | Existing |
| DOS Programs | | DOSBox |
|----------------| | VGA |
| Emulation |
|---------------|
See this guide: https://www.dosbox.com/wiki/Building_DOSBox_with_MinGW
sudo apt install build-essential autoconf automake-1.15 autotools-dev m4
./autogen.sh
./configure
make
./configure --enable-debug
-- OR --
./configure --enable-debug=heavy
Here are some useful online resources:
Here is a handful of links that helped me get started on the ReelMagic side of things:
- https://www.vogons.org/viewtopic.php?t=7364
- https://www.vogons.org/viewtopic.php?t=37363
- http://bitsavers.informatik.uni-stuttgart.de/pdf/c-cube/90-1450-101_CL450_MPEG_Video_Decoder_Users_Manual_1994.pdf
- http://www.oldlinux.org/Linux.old/docs/interrupts/int-html/rb-5094.htm
- http://www.oldlinux.org/Linux.old/docs/interrupts/int-html/rb-4251.htm
This is the awesome MPEG decoder library used for this project. This guy gets it.