Sweden-Number/documentation/multimedia.sgml

  <chapter id="multimedia">
    <title>Wine and Multimedia</title>

    <para>
      This file contains information about the implementation of the
      multimedia layer of Wine.
    </para>

    <para>
      The implementation can be found in the dlls/winmm/ directory (and in
      many of its subdirectories), but also in dlls/msacm/ (for the
      audio compression/decompression manager) and dlls/msvideo/ (for the
      video compression/decompression manager).
    </para>

    <sect1 id="mm-overview">
      <title>Overview</title>

      <para>
	The multimedia stuff is split into 3 layers. The low level (device
	drivers), mid level (MCI commands) and high level abstraction layers.
        The low level layer has also some helper DLLs (like the MSACM/MSACM32
        and MSVIDEO/MSVFW32 pairs).
      </para>

      <para>
	The low level layer may depend on current hardware and OS services
        (like OSS on Unix). Mid level (MCI) and high level layers must be
         written independently from the hardware and OS services.
      </para>

      <para>
	There are two specific low level drivers (msacm.drv for wave input/output,
        midimap.drv for MIDI output only), whose role is:
	<itemizedlist>
	  <listitem>
	    <para>
	      help choosing one low level driver between many
	    </para>
	  </listitem>
	  <listitem>
	    <para>
              add the possibility to convert streams (ie ADPCM =&gt;
              PCM) (this is useful if the format required by the
              application for playback isn't supported by the soundcard). 
            </para>
	  </listitem>
	  <listitem>
	    <para>
	      add the possibility to filter a stream (adding echo, equalizer...
              to a wave stream), or modify the instruments that have to be
              played (MIDI).
	    </para>
	  </listitem>
	</itemizedlist>
      </para>

      <para>
	All of those components are defined as DLLs (one by one).
      </para>

    </sect1>

    <sect1 id="mm-low">
      <title>Low level layers</title>

      <para>
	Please note that native low level drivers are not currently supported
	in Wine, because they either access hardware components or require
	VxDs to be loaded; Wine does not correctly supports those two so far.
      </para>

      <para>
	The following low level layers are implemented (as built-in DLLs):
      </para>

      <sect2>
	<title>(Wave form) Audio</title>

	<para>
	  MMSYSTEM and WINMM call the real low level audio driver using the
	  wodMessage/widMessage which handles the different requests.
	</para>

	<sect3>
	  <title>OSS implementation</title>

	  <para>
	    The low level audio driver is currently only implemented for the
	    OpenSoundSystem (OSS) as supplied in the Linux and FreeBSD kernels by
	    <ulink url="http://www.4front-tech.com/">4Front Technologies</ulink>.
	    The presence of this driver is checked by configure (depends on the
	    &lt;sys/soundcard.h&gt; file). Source code resides in
	    dlls/winmm/wineoss/audio.c.
	  </para>

	  <para>
	    The implementation contains all features commonly used, but has
	    several problems (see TODO list).
	  </para>

	  <para>
	    Note that some Wine specific flag has been added to the wodOpen function,
	    so that the dsound DLL can share the /dev/dsp access. Currently, this
	    only provides mutual exclusion for both DLLs. Future extension could add
	    a virtual mixer between the two output streams.
	  </para>

	  <para>TODO:
	    <itemizedlist>
	      <listitem>
		<para>
		  verify all functions for correctness
		</para>
	      </listitem>
	      <listitem>
		<para>
		  Add virtual mixer between wave-out and dsound interfaces.
		</para>
	      </listitem>
	    </itemizedlist>
	  </para>

	</sect3>

	<sect3>
	  <title>Other sub systems</title>

	  <para>
            Support is also provided for ALSA, aRts, NAS, Jack,
            AudioIO, but with less intensive debugging than the OSS.
          </para>

	  <para>
	    EsounD isn't supported yet. ALSA support still needs a
            couple of refinements.
	  </para>

	</sect3>

      </sect2>

      <sect2>
	<title>MIDI</title>

	<para>
	  MMSYSTEM and WINMM call the low level driver functions using the
	  midMessage and the modMessage functions.
	</para>

	<sect3>
	  <title>OSS driver</title>

	  <para>
	    The low level audio driver is currently only implemented for the
	    OpenSoundSystem (OSS) as supplied in the Linux and FreeBSD kernels by
	    <ulink url="http://www.4front-tech.com/">4Front Technologies</ulink>.
	    The presence of this driver is checked by configure (depends on the
	    &lt;sys/soundcard.h&gt; file, and also some specific defines because
	    MIDI is not supported on all OSes by OSS). Source code resides in
	    dlls/winmm/wineoss/midi.c
	  </para>

	  <para>
	    Both Midi in and Midi out are provided. The type of MIDI devices
	    supported is external MIDI port (requires a MIDI capable device -
	    keyboard...) and OPL/2 synthesis (the OPL/2 patches for all
	    instruments are in midiPatch.c).
	  </para>

	  <para>TODO:
	    <itemizedlist>
	      <listitem>
		<para>
		  use better instrument definition for OPL/2 (midiPatch.c) or use
		  existing instrument definition (from playmidi or kmid) with a
		  .winerc option
		</para>
	      </listitem>
	      <listitem>
		<para>
		  have a look at OPL/3 ?
		</para>
	      </listitem>
	      <listitem>
		<para>
		  implement asynchronous playback of MidiHdr
		</para>
	      </listitem>
	      <listitem>
		<para>
		  implement STREAM'ed MidiHdr (question: how shall we share the code
		  between the midiStream functions in MMSYSTEM/WINMM and the code
		  for the low level driver)
		</para>
	      </listitem>
	      <listitem>
		<para>
		  use a more accurate read mechanism than the one of snooping on
		  timers (like select on fd)
		</para>
	      </listitem>
	    </itemizedlist>
	  </para>

	</sect3>

	<sect3>
	  <title>Other sub systems</title>

	  <para>
	    Could support other MIDI implementation for other sub
            systems (ALSA, any other idea here ?)
	  </para>

	  <para>
	    Could also implement a software synthesizer, either inside Wine or
	    using using MIDI loop back devices in an external program (like
	    timidity). The only trouble is that timidity is GPL'ed...
            Note: this could be achieved using the ALSA sequencer and
            Timidity being used as a server.
	  </para>

	</sect3>

      </sect2>

      <sect2>
	<title>Mixer</title>

	<para>
	  MMSYSTEM and WINMM call the low level driver functions using the
	  mxdMessage function.
	</para>

	<sect3>
	  <title>OSS implementation</title>

	  <para>
	    The current implementation uses the OpenSoundSystem mixer, and resides
	    in dlls/winmm/wineoss/mixer.c
	  </para>

	  <para>TODO:
	    <itemizedlist>
	      <listitem>
		<para>
		  implement notification mechanism when state of mixer's controls
		  change
		</para>
	      </listitem>
	    </itemizedlist>
	  </para>

	</sect3>

	<sect3>
	  <title>Other sub systems</title>

	  <para>TODO:
	    <itemizedlist>
	      <listitem>
		<para>
		  implement mixing low level drivers for other mixers (ALSA...)
		</para>
	      </listitem>
	    </itemizedlist>
	  </para>

	</sect3>

      </sect2>

      <sect2>
	<title>Aux</title>

	<para>
	  The AUX low level driver is the predecessor of the mixer driver
	  (introduced in Win 95).
	</para>

	<sect3>
	  <title>OSS driver</title>

	  <para>
	    The implementation uses the OSS mixer API, and is incomplete.
	  </para>

	  <para>TODO:
	    <itemizedlist>
	      <listitem>
		<para>
		  verify the implementation
		</para>
	      </listitem>
	      <listitem>
		<para>
		  check with what is done in mixer
		</para>
	      </listitem>
	      <listitem>
		<para>
		  open question: shall we implement it on top of the low level mixer
		  functions ?
		</para>
	      </listitem>
	    </itemizedlist>

	  </para>

	</sect3>

      </sect2>

      <sect2>
	<title>Wine OSS</title>

	<para>
	   All the OSS dependent functions are stored into the WineOSS DLL. It still
	   lack a correct installation scheme (as any multimedia device under Windows),
	   so that all the correct keys are created in the registry. This requires
	   an advanced model since, for example, the number of wave out devices can
	   only be known on the destination system (depends on the sound card driven
	   by the OSS interface). A solution would be to install all the multimedia
	   drivers through the SETUPX DLL; this is not doable yet (the multimedia
	   extension to SETUPX isn't written yet).
	</para>

      </sect2>

      <sect2>
	<title>Joystick</title>

	<para>
	  The API consists of the joy* functions found in dlls/winmm/joystick/joystick.c.
	  The implementation currently uses the Linux joystick device driver
	  API. It is lacking support for enhanced joysticks and has not been
	  extensively tested.
	</para>

	<para>TODO:
	  <itemizedlist>
	    <listitem>
	      <para>
		better support of enhanced joysticks (Linux 2.2 interface is available)
	      </para>
	    </listitem>
	    <listitem>
	      <para>
		support more joystick drivers (like the XInput extension)
	      </para>
	    </listitem>
	    <listitem>
	      <para>
		should load joystick DLL as any other driver (instead of hardcoding)
		the driver's name, and load it as any low lever driver.
	      </para>
	    </listitem>
	  </itemizedlist>
	</para>

      </sect2>

      <sect2>
	<title>Wave mapper (msacm.drv)</title>

	<para>
	  The Wave mapper device allows to load on-demand codecs in order to
	  perform software conversion for the types the actual low level driver
	  (hardware). Those codecs are provided through the standard ACM
	  drivers.
	</para>

	<sect3>
	  <title>Built-in</title>

	  <para>
	    A first working implementation for wave out as been provided (wave in
	    exists, but doesn't allow conversion).
	  </para>

	  <para>
	    Wave mapper driver implementation can be found in dlls/winmm/wavemap/
	    directory. This driver heavily relies on MSACM and MSACM32 DLLs which
	    can be found in dlls/msacm and dlls/msacm32. Those DLLs load ACM
	    drivers which provide the conversion to PCM format (which is normally
	    supported by low level drivers). ADPCM, MP3... fit into the category
	    of non PCM formats.
	  </para>

	  <para>
	    There is currently no built-in ACM driver in Wine, so you must use
	    native ones if you're looking for non PCM playback.
   	  </para>

	  <para>TODO:
	    <itemizedlist>
	      <listitem>
		<para>
		  check for correctness and robustness
		</para>
	      </listitem>
	    </itemizedlist>
	  </para>
	</sect3>

	<sect3>
	  <title>Native</title>

	  <para>
	    Seems to work quite ok (using of course native MSACM/MSACM32 DLLs)
	    Some other testings report some issues while reading back the registry
	    settings.
	  </para>

	</sect3>

      </sect2>

      <sect2>
	<title>MIDI mapper</title>

	<para>
	  Midi mapper allows to map each one of 16 MIDI channels to a specific
	  instrument on an installed sound card. This allows for example to
	  support different MIDI instrument definition (XM, GM...). It also
	  permits to output on a per channel basis to different MIDI renderers.
	</para>

	<sect3>
	  <title>Built-in</title>

	  <para>
	    A built-in MIDI mapper can be found in dlls/winmm/midimap/. It partly
	    provides the same functionality as the Windows' one. It allows to pick up
	    destination channels (you can map a given channel to a specific playback
	    device channel (see the configuration bits for more details).
	  </para>

	  <para>TODO:
	    <itemizedlist>
	      <listitem>
		<para>
		  implement the Midi mapper features (instrument on the fly modification)
		  if it has to be done as under Windows, it required parsing the midi
		  configuration files (didn't find yet the specs)
		</para>
	      </listitem>
	    </itemizedlist>
	  </para>

	</sect3>

	<sect3>
	  <title>Native</title>

	  <para>
	    The native midimapper from Win 98 works, but it requires a bunch of
	    keys in the registry which are not part of the Wine source yet.
	  </para>

	  <para>TODO:
	    <itemizedlist>
	      <listitem>
		<para>
		  add native midimapper keys to the registry to let it run. This
		  will require proper multimedia driver installation routines.
		</para>
	      </listitem>
	    </itemizedlist>
	  </para>

	</sect3>

      </sect2>

    </sect1>

    <sect1 id="mm-mci">
      <title>Mid level drivers (MCI)</title>

      <para>
	The mid level drivers are represented by some common API functions,
	mostly mciSendCommand and mciSendString. See status in chapter 3 for
	more information. Wine implements several MCI mid level drivers
	(status is given for both built-in and native implementation):
      </para>

      <para>TODO: (apply to all built-in MCI drivers)
	<itemizedlist>
	  <listitem>
	    <para>
	      use MMSYSTEM multitasking caps instead of the home grown
	    </para>
	  </listitem>
	</itemizedlist>
      </para>


      <sect2>
	<title>CDAUDIO</title>

	<sect3>
	  <title>Built-in</title>

	  <para>
	    The currently best implementation is the MCI CDAUDIO driver that can
	    be found in dlls/winmm/mcicda/mcicda.c. The implementation is mostly
	    complete, there have been no reports of errors. It makes use of
	    dlls/ntdll/cdrom.c Wine cdrom interface.
	    This interface has been ported on Linux, FreeBSD and NetBSD. (Sun
	    should be similar, but are not implemented.)
	  </para>

	  <para>
	    A very small example of a cdplayer consists just of the line
	    mciSendString("play cdaudio",NULL,0,0);
	  </para>

	  <para>TODO:
	    <itemizedlist>
	      <listitem>
		<para>
		  add support for other cdaudio drivers (Solaris...)
		</para>
	      </listitem>
	      <listitem>
		<para>
		  add support for multiple cdaudio devices (plus a decent
                  configuration scheme)
		</para>
	      </listitem>
	    </itemizedlist>
	  </para>

	</sect3>

	<sect3>
	  <title>Native</title>

	  <para>
	    Native MCICDA works also correctly... It uses the MSCDEX traps (on int
	    2f). However, some commands (like seeking) seem to be broken.
	  </para>

	</sect3>

      </sect2>

      <sect2>
	<title>MCIWAVE</title>

	<sect3>
	  <title>Built-in</title>

	  <para>
	    The implementation is rather complete and can be found in
	    dlls/winmm/mciwave/audio.c. It uses the low level audio API (although
	    not abstracted correctly).
	  </para>

	  <para>FIXME:
	    <itemizedlist>
	      <listitem>
		<para>
		  The MCI_STATUS command is broken.
		</para>
	      </listitem>
	    </itemizedlist>
	  </para>

	  <para>TODO:
	    <itemizedlist>
	      <listitem>
		<para>
		  check for correctness
		</para>
	      </listitem>
	      <listitem>
		<para>
		  better use of asynchronous playback from low level
		</para>
	      </listitem>
	      <listitem>
		<para>
		  better implement non waiting command (without the MCI_WAIT flag).
		</para>
	      </listitem>
	    </itemizedlist>
	  </para>

	</sect3>

	<sect3>
	  <title>Native</title>

	  <para>
	    Native MCIWAVE works also correctly.
	  </para>

	</sect3>

      </sect2>

      <sect2>
	<title>MCISEQ (MIDI sequencer)</title>

	<sect3>
	  <title>Built-in</title>

	  <para>
	    The implementation can be found in dlls/winmm/mciseq/mcimidi.c. Except
	    for the Record command, should be close to completion (except for non
	    blocking commands, as many MCI drivers).
	  </para>

	  <para>TODO:
	    <itemizedlist>
	      <listitem>
		<para>
		  implement it correctly
		</para>
	      </listitem>
	      <listitem>
		<para>
		  finish asynchronous commands (especially for reading/record)
		</para>
	      </listitem>
	      <listitem>
		<para>
		  better implement non waiting command (without the MCI_WAIT flag).
		</para>
	      </listitem>
	      <listitem>
		<para>
		  implement the recording features
		</para>
	      </listitem>
	    </itemizedlist>
	  </para>

	</sect3>

	<sect3>
	  <title>Native</title>

	  <para>
	    Native MCIMIDI has been working but is currently blocked by scheduling
	    issues (mmTaskXXX no longer work).
	  </para>
	  <para>FIXME:
	    <itemizedlist>
	      <listitem>
		<para>
		  midiStreamPlay get from time to time an incorrect MidiHdr when
		  using the native MCI sequencer
		</para>
	      </listitem>
	    </itemizedlist>
	  </para>

	</sect3>

      </sect2>

      <sect2>
	<title>MCIANIM</title>

	<sect3>
	  <title>Built-in</title>

	  <para>
	    The implementation is in dlls/winmm/mcianim/.
	  </para>

  	  <para>TODO:
	    <itemizedlist>
	      <listitem>
		<para>
		  implement it, probably using xanim or something similar.
		</para>
	      </listitem>
	    </itemizedlist>
	  </para>

	</sect3>

	<sect3>
	  <title>Native</title>

	  <para>
	    Native MCIANIM is reported to work (but requires native video DLLs
	    also, even though the built-in video DLLs start to work correctly).
	  </para>

	</sect3>

      </sect2>

      <sect2>
	<title>MCIAVI</title>

	<sect3>
	  <title>Built-in</title>

	  <para>
	    The implementation is in dlls/winmm/mcianim/. Basic features are present,
            simple playing is available, even if lots remain to be done. It rather
            heavily relies on MSVIDEO/MSVFW32 DLLs pair to work.
	  </para>

  	  <para>TODO:
	    <itemizedlist>
	      <listitem>
		<para>
		  finish the implementation
		</para>
	      </listitem>
	      <listitem>
		<para>
		  fix the audio/video synchronization issue
		</para>
	      </listitem>
	    </itemizedlist>
	  </para>

	</sect3>

	<sect3>
	  <title>Native</title>

	  <para>
	    Native MCIAVI is reported to work (but requires native video DLLs
	    also). Some files exhibit some deadlock issues anyway.
	  </para>

	</sect3>

      </sect2>

    </sect1>

    <sect1 id="mm-high">
      <title>High level layers</title>

      <para>
	The rest (basically the MMSYSTEM and WINMM DLLs entry points). It also
	provides the skeleton for the core functionality for multimedia
	rendering. Note that native MMSYSTEM and WINMM do not currently work
	under Wine and there is no plan to support them (it would require to
	also fully support VxD, which is not done yet).
        Moreover, native DLLs require 16 bit MCI and low level drivers. Wine
        implements them as 32 bit drivers.
	MCI and low level drivers can either be 16 or 32 bit for Wine.
      </para>

      <para>TODO:
	<itemizedlist>
	  <listitem>
	    <para>
	      it seems that some programs check what's installed in registry
	      against the value returned by drivers. Wine is currently broken
	      regarding this point.
	    </para>
	  </listitem>
	  <listitem>
	    <para>
	      check thread-safeness for MMSYSTEM and WINMM entry points
	    </para>
	  </listitem>
	  <listitem>
	    <para>
	      unicode entry points are badly supported
	    </para>
	  </listitem>
	</itemizedlist>
      </para>

      <sect2>
	<title>MCI skeleton</title>

	<para>
	  Implementation of what is needed to load/unload MCI drivers, and to
	  pass correct information to them. This is implemented in
	  dlls/winmm/mci.c. The mciSendString function uses command strings,
	  which are translated into normal MCI commands as used by
	  mciSendCommand with the help of command tables. The API can be found
	  in dlls/winmm/mmsystem.c and dlls/winmm/mci.c. The functions there
	  (mciOpen,mciSysInfo) handle mid level driver allocation and calls. The
	  implementation is not complete.
        </para>

        <para>
	  MCI drivers are seen as regular Wine modules, and can be loaded (with
	  a correct load order between builtin, native), as any other DLL. 
	  Please note, that MCI drivers module names must bear the .drv 
	  extension to be correctly understood.
        </para>

        <para>
	  The list of available MCI drivers is obtained as follows:
	  1. key 'mci' in [option] section from .winerc (or wineconf)
	  mci=CDAUDIO:SEQUENCER gives the list of MCI drivers (names, in
	  uppercase only) to be used in Wine.
	  2. This list, when defined, supersedes the mci key in
	  c:\windows\system.ini
       </para>

	<para>
	  Note that native VIDEODISC crashes when the module is loaded, which
	  occurs when the MCI procedures are initialized. Make sure that this is
	  not in the list from above. Try adding:
	  mci=CDAUDIO:SEQUENCER:WAVEAUDIO:AVIVIDEO:MPEGVIDEO
	  to the [options] section of the wine config file.
	</para>

	<para>TODO:
	  <itemizedlist>
	    <listitem>
	      <para>
		correctly handle the MCI_ALL_DEVICE_ID in functions.
	      </para>
	    </listitem>
	    <listitem>
	      <para>
		finish mapping 16 <=> 32 of MCI structures and commands
	      </para>
	    </listitem>
	    <listitem>
	      <para>
		MCI_SOUND is not handled correctly (should not be sent to MCI
		driver =&gt; same behavior as MCI_BREAK)
	      </para>
	    </listitem>
	    <listitem>
	      <para>
		implement auto-open feature (ie, when a string command is issued
		for a not yet opened device, MCI automatically opens it)
	      </para>
	    </listitem>
	  </itemizedlist>
	</para>

      </sect2>

      <sect2>
	<title>MCI multi-tasking</title>

	<para>
	  Multi-tasking capabilities used for the MCI drivers are provided in
	  dlls/winmm/mmsystem.c.
	</para>

	<para>TODO:
	  <itemizedlist>
	    <listitem>
	      <para>
		mmTaskXXX functions are currently broken because the 16 loader does
		not support binary command lines =&gt; provide Wine's own mmtask.tsk not
		using binary command line.
	      </para>
	    </listitem>
	  </itemizedlist>
	</para>

      </sect2>

      <sect2>
	<title>Timers</title>

	<para>
	  It currently uses a service thread, run in the context of the calling
	  process, which should correctly mimic Windows behavior.
	</para>

	<para>TODO:
	  <itemizedlist>
	    <listitem>
	      <para>
		Check if minimal time is satisfactory for most programs.
	      </para>
	    </listitem>
	    <listitem>
	      <para>
		current implementation may let a timer tick (once) after it has
		been destroyed
	      </para>
	    </listitem>
	  </itemizedlist>
	</para>

      </sect2>

      <sect2>
	<title>MMIO</title>

	<para>
	  The API consists of the mmio* functions found in dlls/winmm/mmio.c.
	  Seems to work ok in most of the cases. There's some linear/segmented
	  issues with 16 bit code. There are also some bugs when writing MMIO
          files.
	</para>

      </sect2>

      <sect2>
	<title>sndPlayXXX functions</title>

	<para>
	  Seem to work correctly.
	</para>

      </sect2>

    </sect1>

    <sect1 id="mm-conf">
      <title>Multimedia configuration</title>

      <para>
	Currently, multimedia configuration heavily relies on Win 3.x
	configuration model.
      </para>

      <sect2>
	<title>Drivers</title>

	<para>
	  Since all multimedia drivers (MCI, low level ones, ACM drivers,
	  mappers) are, at first, drivers they need to appear in the [mci] or
	  [mci32] section of the system.ini file.
	  Since all drivers are, at first, DLLs, you can choose to load their
	  Wine's (built-in) or Windows (native) version.
	</para>

      </sect2>

      <sect2>
	<title>MCI</title>

	<para>
	  A default [mci] section (in system.ini) looks like (see the note above
	  on videodisc):
	</para>

	<screen>
   [mci]
   cdaudio=mcicda.drv
   sequencer=mciseq.drv
   waveaudio=mciwave.drv
   avivideo=mciavi.drv
   videodisc=mcipionr.drv
   vcr=mcivisca.drv
   MPEGVideo=mciqtz.drv
	</screen>

	<para>
	  By default, the list of loadable MCI drivers will be made of those
	  drivers (in the [mci] section).
	</para>

	<para>
	  The list of loadable (recognized) MCI drivers can be altered in the
	  [option] section of the wine config file, like:
	  mci=CDAUDIO:SEQUENCER:WAVEAUDIO:AVIVIDEO:MPEGVIDEO
	</para>

	<para>TODO:
	  <itemizedlist>
	    <listitem>
	      <para>
		use a default registry setting to bypass this (ugly) configuration
		model
	      </para>
	    </listitem>
	    <listitem>
	      <para>
		we need also a generic tool to let the end user pick
                up his/her driver depending on the hardware present on the machine.
		model
	      </para>
	    </listitem>
	  </itemizedlist>
	</para>

      </sect2>

      <sect2>
	<title>Low level drivers</title>

	<para>
           Configuration of low level drivers is done with the Wine configuration file.
	   Default keys are provided in wine.inf.
	</para>

	<para>
	  The registry keys used here differ from the Windows' one. Using the Windows' one
	  would require implementing something equivalent to a (real) driver installation.
	  Even if this would be necessary in a few cases (mainly using MS native multimedia)
	  modules, there's no real need so far (or it hasn't been run into yet).
	</para>

	<para>
	  See the configuration part of the User's Guide for more details.
	</para>

      </sect2>

      <sect2>
	<title>Midi mapper</title>

	<para>
          The Midi mapper configuration is the same as on Windows 9x. Under the key
	  <screen>
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Multimedia\MIDIMap
	  </screen>
	  if the 'UseScheme' value is not set, or is set to a null value, the midi
	  mapper will always use the driver identified by the 'CurrentInstrument'
	  value. Note: Wine (for simplicity while installing) allows to define
	  'CurrentInstrument' as "#n" (where n is a number), whereas Windows only
	  allows the real device name here. If UseScheme is set to a non null value,
	  'CurrentScheme' defines the name of the scheme to map the different channels.
	  All the schemes are available with keys like
	  <screen>
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\MediaProperties\PrivateProperties\Midi\Schemes\%name_of_scheme%
	  </screen>
	  For every scheme, under this key, will be a sub-key (which name is usually
	  a two digit index, starting at 00). Its default value is the name of the
	  output driver, and the value 'Channels' lists all channels (of the 16
	  standard MIDI ones) which have to be copied to this driver.
	</para>

	<para>
	  To provide enhanced configuration and mapping capabilities, each driver
	  can define under the key
	  <screen>
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\MediaProperties\PrivateProperties\Midi\Ports\%driver_name%
	  </screen>
	  a link to and .IDF file which allows to remap channels internally (for
	  example 9 -&gt; 16), to change instruments identification, event
	  controllers values. See the source file dlls/winmm/midimap/midimap.c
	  for the details (this isn't implemented yet).
	</para>
      </sect2>

      <sect2>
	<title>ACM</title>

	<para>
	  To be done (use the same mechanism as MCI drivers configuration).
	</para>

      </sect2>

      <sect2>
	<title>VIDC</title>

	<para>
	  To be done (use the same mechanism as MCI drivers configuration).
	</para>

      </sect2>

    </sect1>

    <sect1 id="mm-arch">
      <title>Multimedia architecture</title>

      <sect2>
	<title>Windows 9x multimedia architecture</title>

	<screen>
             |
Kernel space |                    Client applications
             |
             |           | |         ^ ^       | |          | |
             |        16>| |<32   16>| |<32 16>| |<32    16>| |<32
             |           | v         | |       | v          | v
             |      +----|-----------|---------|------------|-------+
             |      |    |           |         |            |       |  WinMM.dll
             |      |    |           |         |            |       |   32 bit
             |      +----|-----------|---------|------------|-------+
             |           | |         | ^       | |          |
             |  +------+ | |<16      | |       | |<16       |
             |  |   16>| | |         | |       | |          |
             |  |      v v v         | |       v v          v
             |  |   +---------------+---+-------------+-------------+
             |  |   | waveInXXX     |   | mciXXX      | *playSound* |
             |  |   | waveOutXXX    |   |             | mmioXXX     |
             |  |   | midiInXXX     |   |             | timeXXX     |
             |  |   | midiOutXXX    |   |             | driverXXX   |
             |  |   | midiStreamXXX |   |             |             |  MMSystem.dll
             |  |   | mixerXXX      |   |             |             |     16 bit
 +--------+  |  |   | auxXXX    +---+   +---+ mmThread|             |
 |MMDEVLDR|<------->| joyXXX    | Call back | mmTask  |             |
 +--------+  |  |   +-----------+-----------+---------+-------------+
     ^       |  |          |       ^    ^     | ^
     |       |  |       16>|       |<16>|  16>| |<16
     v       |  |          v       |    |     v |
 +--------+  |  |   +-------------+    +----------+
 |  VxD   |<------->|    *.drv    |    | mci*.drv |
 +--------+  |  |   +--------------+   +-----------+
             |  |    |  msacm.drv  |    | mciwave  |
             |  |    +--------------+   +-----------+
             |  |     | midimap.drv |    | mcimidi  |
             |  |     +-------------+    +-----------+
             |  |    Low-level drivers    |    ...   | MCI drivers
             |  |                         +----------+
             |  |                               |
             |  |                               |<16
             |  +-------------------------------+
             |
	</screen>

	<para>
	  The important points to notice are:
	  <itemizedlist>
	    <listitem>
	      <para>
		all drivers (and most of the core code) is 16 bit
	      </para>
	    </listitem>
	    <listitem>
	      <para>
		all hardware (or most of it) dependent code reside in the kernel
		space (which is not surprising)
	      </para>
	    </listitem>
	  </itemizedlist>
	</para>

      </sect2>

      <sect2>
	<title>Wine multimedia architecture</title>

	<screen>
             |
Kernel space |                    Client applications
             |
             |           | |         ^ ^       | |          | |
             |        16>| |<32   16>| |<32 16>| |<32    16>| |<32
             |           | |         | |       | |          | |
             |  +------+ | |         | |       | |          | |
             |  |32/16>| | |         | |       | |          | |
             |  |      v v v         | |       v v          v v
             |  |   +---------------+---+-------------+-------------+
             |  |   | waveInXXX     |   | mciXXX      | *playSound* |
             |  |   | waveOutXXX    |   |             | mmioXXX     | WinMM.dll
             |  |   | midiInXXX     |   |             | timeXXX     |   32 bit
             |  |   | midiOutXXX    |   |             | driverXXX   |
             |  |   | midiStreamXXX |   |             |             | MMSystem.dll
             |  |   | mixerXXX      |   |             |             |   16 bit
             |  |   | auxXXX    +---+   +---+ mmThread|             |
             |  |   | joyXXX    | Call back | mmTask  |             |
             |  |   +-----------+-----------+---------+-------------+
             |  |         ||      ^    ^     ||    ^^
             |  |      16>||<32   |<16>|  16>||<32>||<16
             |  |         vv      |<32>|     vv    ||
+---------+  |  |   +-------------+    +----------+
|HW driver|<------->|    *.drv    |    | mci*.drv |
+---------+  |  |   +--------------+   +-----------+
             |  |    |  msacm.drv  |    | mciwave  |
             |  |    +--------------+   +-----------+
             |  |     | midimap.drv |    | mcimidi  |
             |  |     +-------------+    +-----------+
             |  |    Low-level drivers    |    ...   | MCI drivers
             |  |                         +----------+
             |  |                               |
             |  |                               |<32/16
             |  +-------------------------------+
             |
	</screen>

	<para>
	  From the previous drawings, the most noticeable differences are:
	  <itemizedlist>
	    <listitem>
	      <para>
		low-level drivers can either be 16 or 32 bit
	      </para>
	    </listitem>
	    <listitem>
	      <para>
		MCI drivers can either be 16 or 32 bit
	      </para>
	    </listitem>
	    <listitem>
	      <para>
		MMSystem and WinMM will be hosted in a single elfglue library
	      </para>
	    </listitem>
	    <listitem>
	      <para>
		no link between the MMSystem/WinMM pair on kernel space shall
		exist. For example, there will be a low level driver to talk to a
		UNIX OSS (Open Sound System) driver
	      </para>
	    </listitem>
	    <listitem>
	      <para>
		all built-in drivers (low-level and MCI) will be written as 32 bit
		drivers
	      </para>
	    </listitem>
	    <listitem>
	      <para>
		all native drivers will be 16 bits drivers
	      </para>
	    </listitem>
	  </itemizedlist>
	</para>

      </sect2>

    </sect1>

    <sect1 id="msacm">
      <title>MS ACM Dlls</title>

      <sect2>
	<title>Contents</title>

	<para>tbd</para>
      </sect2>

      <sect2>
	<title>Status</title>

	<para>tbd</para>
      </sect2>

      <sect2>
	<title>Caching</title>

	<para>
	  The MSACM/MSACM32 keeps some data cached for all known ACM
	  drivers. Under the key
          <screen>
		  Software\Microsoft\AudioCompressionManager\DriverCache\&lt;driver
		  name&gt;
	  </screen>
	  , are kept for values:
	    <itemizedlist>
	      <listitem>
	        <para>
                      aFormatTagCache which contains an array of
		      DWORD. There are two DWORDs per cFormatTags
		      entry. The first DWORD contains a format tag
		      value, and the second the associated maximum
		      size for a WAVEFORMATEX structure.
		      (Fields dwFormatTag and cbFormatSize from
		      ACMFORMATDETAILS)
                 </para>
	      </listitem>
	      <listitem>
	        <para>
		      cFilterTags contains the number of tags supported by the driver
		      for filtering.
		</para>
	      </listitem>
	      <listitem>
	        <para>
		      cFormatTags contains the number of tags support
		      by the driver for conversions.
		</para>
	      </listitem>
	      <listitem>
	        <para>
		      fdwSupport (the same as the one returned from
		      acmDriverDetails).
		</para>
	      </listitem>
	    </itemizedlist>
	  </para>

	<para>
		The cFilterTags, cFormatTags, fdwSupport are the same
		values as the ones returned from acmDriverDetails
		function.
	</para>
      </sect2>
    </sect1>

  </chapter>

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