196 lines
7.1 KiB
Plaintext
196 lines
7.1 KiB
Plaintext
This file contains information about the implementation of the multimedia
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layer of WINE.
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The libraries consist of MMSYSTEM.DLL (win16), WINMM.DLL (win32) and some
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(abstracted, not Windows compatible) lowlevel drivers. The implementation
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can be found in the multimedia/ subdirectory.
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The multimedia stuff is split into 3 layers. The lowlevel (device drivers),
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midlevel (MCI commands) and highlevel abstraction layers.
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The lowlevel may depend on current hardware and OS services (like OSS).
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Mid-level and high-level must be written independantly from the hardware and OS
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services.
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1. Lowlevel layers
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Following lowlevel layers are implemented:
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1.1 (Waveform) Audio
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The API consists of the waveIn*/waveOut* functions found in
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multimedia/mmsystem.c. They call the real lowlevel audiodriver using
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the wodMessage/widMessage function in multimedia/audio.c, which handles
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the different requests.
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The lowlevel audio driver is currently only implemented for the
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OpenSoundSystem (OSS) as supplied in the Linux and FreeBSD kernels by
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4Front Technologies (http://www.4front-tech.com/). The presence of this
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driver is checked by configure (depends on the <sys/soundcard.h> file).
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The implementation contains all features commonly used, but has several
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problems. For instance:
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Writes and reads are not done asynchronously as they are supposed to
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be done. This breaks some programs (soundrec.exe from the Windows applets),
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but doesn't worry other programs. Some callbacks are probably done
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incorrectly (there are reports of some broken multimedia applications,
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but I haven't found one yet.)
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TODO:
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- add asynchronous writes and reads (must use threads)
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- check the callback functions
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- verify all functions for correctness
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- add drivers for other soundsystems (Sun Audio, remote audio systems
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(using X extensions, ...)
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1.2 Mixer
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The API consists of the mixer* functions found in multimedia/mmsystem.c.
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They call the lowlevel driver functions in multimedia/mixer.c using the
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mixMessage function.
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The current implementation tries to use the OpenSoundSystem mixer, but is
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missing nearly everything. There is no report of a working application.
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TODO:
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- implement mixing functionality for OSS correctly.
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- implement mixing lowlevel drivers for other mixers.
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1.3 MIDI
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The API consists of the midi* functions found in multimedia/mmsystem.c.
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They call the lowlevel driver functions in multimedia/midi.c using the
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midMessage and the modMessage functions.
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The lowlevel audio driver is currently only implemented for the
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OpenSoundSystem (OSS) as supplied in the Linux and FreeBSD kernels by
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4Front Technologies (http://www.4front-tech.com/). The presence of this
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driver is checked by configure (depends on the <sys/soundcard.h> file).
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Both Midi in and Midi out are provided. The type of MIDI devices supported
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is external MIDI port (requires an MIDI capable device - keyboard...) and
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OPL/2 synthesis (the OPL/2patches for all instruments are in midiPatch.c).
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TODO:
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- Do not implement a software synthesizer. This should be done
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using MIDI loopback devices in an external program (like timidity).
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the only trouble is that timidity is GPL'ed...
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- use better instrument definition for OPL/2 (midiPatch.c)
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- have a look at OPL/3 ?
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- a hack is used in mmsystem.c (setting reserved to the 32 bit linear
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address of the block whatever the call is made from 16 or 32 bits
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code...). this should be made in midi.c I think
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1.4 Timers
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The API consists of the timer* functions found in multimedia/timer.c.
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There is currently only one implementation, which uses normal windows timers.
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The implementation works for most cases found. The only problem is that
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it doesn't support asynchronous timer events (as it is supposed to do).
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There is a workaround for this lack in timeGetTime() to make Diablo work
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and 'Pinball! SpaceCadet' at least start up.
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TODO:
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- Implemented asynchronous timers (using a thread probably)
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1.5 MMIO
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The API consists of the mmio* functions found in multimedia/mmio.c.
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FIXME: I am not sure about the status of this implementation.
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TODO:
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- add win32 support.
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- ...
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1.6 AUX
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The API consists of the aux* functions found in multimedia/mmsystem.c.
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They call auxMessage in multimedia/mmaux.c.
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The aux* functions are the predecessor of the mixer* functions.
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The implementation uses the OSS mixer API, and is incomplete.
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TODO:
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- verify the implementation
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1.7 JOYSTICK
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The API consists of the joy* functions found in multimedia/joystick.c.
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The implementation currently uses the Linux joystick device driver API.
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It is lacking support for enhanced joysticks and has not been extensively
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tested.
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TODO:
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- better support of enhanced joysticks
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- support more joystick drivers (like the XInput extension)
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2. Midlevel drivers (MCI)
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The midlevel drivers are represented by some common API functions,
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mostly mciSendCommand and mciSendString. The mciSendString function
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uses commandstrings, which are translated into normal MCI commands as
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used by mciSendCommand. The API can be found in multimedia/mmsystem.c
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and multimedia/mcistring.c.
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The functions there (mciOpen,mciSysInfo) handle midlevel driver
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allocation and calls.
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The implementation is not complete.
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TODO:
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- support windows MCI drivers (should be possible for they usually
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do not use lowlevel calls)
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- MCI command loading support
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- better implement non waiting command (without the MCI_WAIT flag).
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First shot is present in midi.c but requires much more work (and
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will impact sndPlaySound() as well which shall be written as
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as set of MCI commands).
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- implement other stuff as yet unknown
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WINE implements several MCI midlevel drivers:
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2.1 CDAUDIO
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The currently best implementation is the MCI CDAUDIO driver that can
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be found in multimedia/mcicda.c. The implementation is mostly complete,
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there have been no reports of errors.
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The implementation currently uses only the Linux /dev/cdrom controlling
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functions. (Sun and BSD like should be similair, but are not implemented.)
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A very small example of a cdplayer consists just of the line
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mciSendString("play cdaudio",NULL,0,0);
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TODO:
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- add support for other cdaudio drivers
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2.2 MCIWAVE
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The implementation is rather complete and can be found in
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multimedia/audio.c.
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It uses the lowlevel audio API (although not abstracted correctly).
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FIXME: The MCI_STATUS command is broken.
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TODO: - check for correctness
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2.3 MIDI/SEQUENCER
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The implementation can be found in multimedia/midi.c. Except from the
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Record command, should be close to completion (except for non blocking
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commands).
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TODO:
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- implement it correctly
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- finish asynchronous commands
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2.4 MCIANIM
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The implementation consists of stubs and is in multimedia/mcianim.c.
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TODO:
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- implement it, probably using xanim or something similair. Could
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also be implemented by using the Windows MCI video drivers.
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3 High-level layers
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The rest (basically the MMSYSTEM and WINMM DLLs entry points.
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