gzdoom/src/sound/musicformats/music_midistream.cpp

/*
** music_midistream.cpp
** Implements base class for MIDI and MUS streaming.
**
**---------------------------------------------------------------------------
** Copyright 2008 Randy Heit
** All rights reserved.
**
** Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions
** are met:
**
** 1. Redistributions of source code must retain the above copyright
**    notice, this list of conditions and the following disclaimer.
** 2. Redistributions in binary form must reproduce the above copyright
**    notice, this list of conditions and the following disclaimer in the
**    documentation and/or other materials provided with the distribution.
** 3. The name of the author may not be used to endorse or promote products
**    derived from this software without specific prior written permission.
**
** THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
** IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
** OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
** IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
** NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
** THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
**---------------------------------------------------------------------------
**
*/

// HEADER FILES ------------------------------------------------------------


#include "i_musicinterns.h"
#include "templates.h"
#include "doomdef.h"
#include "m_swap.h"
#include "doomerrors.h"

// MACROS ------------------------------------------------------------------

#define MAX_TIME	(1000000/10)	// Send out 1/10 of a sec of events at a time.

#define EXPORT_LOOP_LIMIT	30		// Maximum number of times to loop when exporting a MIDI file.
									// (for songs with loop controller events)

// EXTERNAL FUNCTION PROTOTYPES --------------------------------------------

// PUBLIC FUNCTION PROTOTYPES ----------------------------------------------

// PRIVATE FUNCTION PROTOTYPES ---------------------------------------------

static void WriteVarLen (TArray<uint8_t> &file, uint32_t value);

// EXTERNAL DATA DECLARATIONS ----------------------------------------------

EXTERN_CVAR(Float, snd_musicvolume)
EXTERN_CVAR(Int, snd_mididevice)

#ifdef _WIN32
extern unsigned mididevice;
#endif

extern char MIDI_EventLengths[7];

// PRIVATE DATA DEFINITIONS ------------------------------------------------

static const uint8_t StaticMIDIhead[] =
{
	'M','T','h','d', 0, 0, 0, 6,
	0, 0, // format 0: only one track
	0, 1, // yes, there is really only one track
	0, 0, // divisions (filled in)
	'M','T','r','k', 0, 0, 0, 0,
	// The first event sets the tempo (filled in)
	0, 255, 81, 3, 0, 0, 0
};

// PUBLIC DATA DEFINITIONS -------------------------------------------------

// CODE --------------------------------------------------------------------

//==========================================================================
//
// MIDIStreamer Constructor
//
//==========================================================================

MIDIStreamer::MIDIStreamer(EMidiDevice type, const char *args)
:
  MIDI(0), Division(0), InitialTempo(500000), DeviceType(type), Args(args)
{
	memset(Buffer, 0, sizeof(Buffer));
}

//==========================================================================
//
// MIDIStreamer OPL Dumping Constructor
//
//==========================================================================

MIDIStreamer::MIDIStreamer(const char *dumpname, EMidiDevice type)
:
  MIDI(0), Division(0), InitialTempo(500000), DeviceType(type), DumpFilename(dumpname)
{
	memset(Buffer, 0, sizeof(Buffer));
}

//==========================================================================
//
// MIDIStreamer Destructor
//
//==========================================================================

MIDIStreamer::~MIDIStreamer()
{
	Stop();
	if (MIDI != NULL)
	{
		delete MIDI;
	}
}

//==========================================================================
//
// MIDIStreamer :: IsMIDI
//
// You bet it is!
//
//==========================================================================

bool MIDIStreamer::IsMIDI() const
{
	return true;
}

//==========================================================================
//
// MIDIStreamer :: IsValid
//
//==========================================================================

bool MIDIStreamer::IsValid() const
{
	return Division != 0;
}

//==========================================================================
//
// MIDIStreamer :: CheckCaps
//
// Called immediately after the device is opened in case a subclass should
// want to alter its behavior depending on which device it got.
//
//==========================================================================

void MIDIStreamer::CheckCaps(int tech)
{
}

//==========================================================================
//
// MIDIStreamer :: SelectMIDIDevice									static
//
// Select the MIDI device to play on
//
//==========================================================================

EMidiDevice MIDIStreamer::SelectMIDIDevice(EMidiDevice device)
{
	/* MIDI are played as:
		- OPL: 
			- if explicitly selected by $mididevice 
			- when snd_mididevice  is -3 and no midi device is set for the song

		- Timidity: 
			- if explicitly selected by $mididevice 
			- when snd_mididevice  is -2 and no midi device is set for the song

		- MMAPI (Win32 only):
			- if explicitly selected by $mididevice (non-Win32 redirects this to Sound System)
			- when snd_mididevice  is >= 0 and no midi device is set for the song
			- as fallback when both OPL and Timidity failed and snd_mididevice is >= 0
	*/

	// Choose the type of MIDI device we want.
	if (device != MDEV_DEFAULT)
	{
		return device;
	}
	switch (snd_mididevice)
	{
	case -1:		return MDEV_SNDSYS;
	case -2:		return MDEV_TIMIDITY;
	case -3:		return MDEV_OPL;
	case -4:		return MDEV_GUS;
#ifdef HAVE_FLUIDSYNTH
	case -5:		return MDEV_FLUIDSYNTH;
#endif
	case -6:		return MDEV_WILDMIDI;
	default:
		#ifdef _WIN32
					return MDEV_MMAPI;
		#else
					return MDEV_SNDSYS;
		#endif
	}
}

//==========================================================================
//
// MIDIStreamer :: CreateMIDIDevice
//
//==========================================================================

MIDIDevice *MIDIStreamer::CreateMIDIDevice(EMidiDevice devtype)
{
	switch (devtype)
	{
	case MDEV_MMAPI:
#ifdef _WIN32
		return CreateWinMIDIDevice(mididevice);
#endif
		assert(0);
		// Intentional fall-through for non-Windows systems.

	case MDEV_GUS:
		return new TimidityMIDIDevice(Args);

#ifdef HAVE_FLUIDSYNTH
	case MDEV_FLUIDSYNTH:
		return new FluidSynthMIDIDevice(Args);
#endif

	case MDEV_SNDSYS:
#ifdef HAVE_FLUIDSYNTH
		return new FluidSynthMIDIDevice(nullptr);
#endif
		// if no FluidSynth, fall through to OPL.

	case MDEV_OPL:
		try
		{
			return new OPLMIDIDevice(Args);
		}
		catch (CRecoverableError &err)
		{
			// The creation of an OPL MIDI device can abort with an error if no GENMIDI lump can be found.
			Printf("Unable to create OPL MIDI device: %s\nFalling back to default playback", err.GetMessage());
#ifdef HAVE_FLUIDSYNTH
			return new FluidSynthMIDIDevice(nullptr);
#else
			// Someone dared to compile GZDoom without FluidSynth support and then started an IWAD without GENMIDI support. Ugh...
			return nullptr;
#endif
		}

	case MDEV_TIMIDITY:
		return CreateTimidityPPMIDIDevice(Args);

	case MDEV_WILDMIDI:
		return new WildMIDIDevice(Args);

	default:
		return NULL;
	}
}

//==========================================================================
//
// MIDIStreamer :: Play
//
//==========================================================================

void MIDIStreamer::Play(bool looping, int subsong)
{
	EMidiDevice devtype;

	m_Status = STATE_Stopped;
	m_Looping = looping;
	EndQueued = 0;
	VolumeChanged = false;
	Restarting = true;
	InitialPlayback = true;

	assert(MIDI == NULL);
	devtype = SelectMIDIDevice(DeviceType);
	if (DumpFilename.IsNotEmpty())
	{
		if (devtype == MDEV_OPL)
		{
			MIDI = new OPLDumperMIDIDevice(DumpFilename);
		}
		else if (devtype == MDEV_GUS)
		{
			MIDI = new TimidityWaveWriterMIDIDevice(DumpFilename, 0);
		}
	}
	else
	{
		MIDI = CreateMIDIDevice(devtype);
	}
	
	if (MIDI == NULL || 0 != MIDI->Open(Callback, this))
	{
		Printf(PRINT_BOLD, "Could not open MIDI out device\n");
		if (MIDI != NULL)
		{
			delete MIDI;
			MIDI = NULL;
		}
		return;
	}

	SetMIDISubsong(subsong);
	CheckCaps(MIDI->GetTechnology());

	if (MIDI->Preprocess(this, looping))
	{
		StartPlayback();
		if (MIDI == NULL)
		{ // The MIDI file had no content and has been automatically closed.
			return;
		}
	}

	if (0 != MIDI->Resume())
	{
		Printf ("Starting MIDI playback failed\n");
		Stop();
	}
	else
	{
		m_Status = STATE_Playing;
	}
}

//==========================================================================
//
// MIDIStreamer :: StartPlayback
//
//==========================================================================

void MIDIStreamer::StartPlayback()
{
	Precache();
	LoopLimit = 0;

	// Set time division and tempo.
	if (0 != MIDI->SetTimeDiv(Division) ||
		0 != MIDI->SetTempo(Tempo = InitialTempo))
	{
		Printf(PRINT_BOLD, "Setting MIDI stream speed failed\n");
		MIDI->Close();
		return;
	}

	MusicVolumeChanged();	// set volume to current music's properties
	OutputVolume(Volume);

	MIDI->InitPlayback();

	// Fill the initial buffers for the song.
	BufferNum = 0;
	do
	{
		int res = FillBuffer(BufferNum, MAX_EVENTS, MAX_TIME);
		if (res == SONG_MORE)
		{
			if (0 != MIDI->StreamOutSync(&Buffer[BufferNum]))
			{
				Printf ("Initial midiStreamOut failed\n");
				Stop();
				return;
			}
			BufferNum ^= 1;
		}
		else if (res == SONG_DONE)
		{
			// Do not play super short songs that can't fill the initial two buffers.
			Stop();
			return;
		}
		else
		{
			Stop();
			return;
		}
	}
	while (BufferNum != 0);
}

//==========================================================================
//
// MIDIStreamer :: Pause
//
// "Pauses" the song by setting it to zero volume and filling subsequent
// buffers with NOPs until the song is unpaused. A MIDI device that
// supports real pauses will return true from its Pause() method.
//
//==========================================================================

void MIDIStreamer::Pause()
{
	if (m_Status == STATE_Playing)
	{
		m_Status = STATE_Paused;
		if (!MIDI->Pause(true))
		{
			OutputVolume(0);
		}
	}
}

//==========================================================================
//
// MIDIStreamer :: Resume
//
// "Unpauses" a song by restoring the volume and letting subsequent
// buffers store real MIDI events again.
//
//==========================================================================

void MIDIStreamer::Resume()
{
	if (m_Status == STATE_Paused)
	{
		if (!MIDI->Pause(false))
		{
			OutputVolume(Volume);
		}
		m_Status = STATE_Playing;
	}
}

//==========================================================================
//
// MIDIStreamer :: Stop
//
// Stops playback and closes the player thread and MIDI device.
//
//==========================================================================

void MIDIStreamer::Stop()
{
	EndQueued = 4;

	if (MIDI != NULL && MIDI->IsOpen())
	{
		MIDI->Stop();
		MIDI->UnprepareHeader(&Buffer[0]);
		MIDI->UnprepareHeader(&Buffer[1]);
		MIDI->Close();
	}
	if (MIDI != NULL)
	{
		delete MIDI;
		MIDI = NULL;
	}
	m_Status = STATE_Stopped;
}

//==========================================================================
//
// MIDIStreamer :: IsPlaying
//
//==========================================================================

bool MIDIStreamer::IsPlaying()
{
	if (m_Status != STATE_Stopped && (MIDI == NULL || (EndQueued != 0 && EndQueued < 4)))
	{
		Stop();
	}
	if (m_Status != STATE_Stopped && !MIDI->IsOpen())
	{
		Stop();
	}
	return m_Status != STATE_Stopped;
}

//==========================================================================
//
// MIDIStreamer :: MusicVolumeChanged
//
// WinMM MIDI doesn't go through the sound system, so the normal volume
// changing procedure doesn't work for it.
//
//==========================================================================

void MIDIStreamer::MusicVolumeChanged()
{
	if (MIDI != NULL && MIDI->FakeVolume())
	{
		float realvolume = clamp<float>(snd_musicvolume * relative_volume, 0.f, 1.f);
		Volume = clamp<uint32_t>((uint32_t)(realvolume * 65535.f), 0, 65535);
	}
	else
	{
		Volume = 0xFFFF;
	}
	if (m_Status == STATE_Playing)
	{
		OutputVolume(Volume);
	}
}

//==========================================================================
//
// MIDIStreamer :: TimidityVolumeChanged
//
//==========================================================================

void MIDIStreamer::TimidityVolumeChanged()
{
	if (MIDI != NULL)
	{
		MIDI->TimidityVolumeChanged();
	}
}

//==========================================================================
//
// MIDIStreamer :: FluidSettingInt
//
//==========================================================================

void MIDIStreamer::FluidSettingInt(const char *setting, int value)
{
	if (MIDI != NULL)
	{
		MIDI->FluidSettingInt(setting, value);
	}
}

//==========================================================================
//
// MIDIStreamer :: FluidSettingNum
//
//==========================================================================

void MIDIStreamer::FluidSettingNum(const char *setting, double value)
{
	if (MIDI != NULL)
	{
		MIDI->FluidSettingNum(setting, value);
	}
}

//==========================================================================
//
// MIDIDeviceStreamer :: FluidSettingStr
//
//==========================================================================

void MIDIStreamer::FluidSettingStr(const char *setting, const char *value)
{
	if (MIDI != NULL)
	{
		MIDI->FluidSettingStr(setting, value);
	}
}


//==========================================================================
//
// MIDIDeviceStreamer :: WildMidiSetOption
//
//==========================================================================

void MIDIStreamer::WildMidiSetOption(int opt, int set)
{
	if (MIDI != NULL)
	{
		MIDI->WildMidiSetOption(opt, set);
	}
}


//==========================================================================
//
// MIDIStreamer :: OutputVolume
//
// Signals the buffer filler to send volume change events on all channels.
//
//==========================================================================

void MIDIStreamer::OutputVolume (uint32_t volume)
{
	if (MIDI != NULL && MIDI->FakeVolume())
	{
		NewVolume = volume;
		VolumeChanged = true;
	}
}

//==========================================================================
//
// MIDIStreamer :: VolumeControllerChange
//
// Some devices don't support master volume
// (e.g. the Audigy's software MIDI synth--but not its two hardware ones),
// so assume none of them do and scale channel volumes manually.
//
//==========================================================================

int MIDIStreamer::VolumeControllerChange(int channel, int volume)
{
	ChannelVolumes[channel] = volume;
	// If loops are limited, we can assume we're exporting this MIDI file,
	// so we should not adjust the volume level.
	return LoopLimit != 0 ? volume : ((volume + 1) * Volume) >> 16;
}

//==========================================================================
//
// MIDIStreamer :: Callback											Static
//
//==========================================================================

void MIDIStreamer::Callback(void *userdata)
{
	MIDIStreamer *self = (MIDIStreamer *)userdata;

	if (self->EndQueued >= 4)
	{
		return;
	}
	self->ServiceEvent();
}

//==========================================================================
//
// MIDIStreamer :: Update
//
// Called periodically to see if the player thread is still alive. If it
// isn't, stop playback now.
//
//==========================================================================

void MIDIStreamer::Update()
{
	if (MIDI != nullptr && !MIDI->Update()) Stop();
}

//==========================================================================
//
// MIDIStreamer :: ServiceEvent
//
// Fills the buffer that just finished playing with new events and appends
// it to the MIDI stream queue. Stops the song if playback is over. Returns
// non-zero if a problem occured and playback should stop.
//
//==========================================================================

int MIDIStreamer::ServiceEvent()
{
	int res;

	if (EndQueued == 2)
	{
		return 0;
	}
	if (0 != (res = MIDI->UnprepareHeader(&Buffer[BufferNum])))
	{
		return res;
	}
fill:
	if (EndQueued == 1)
	{
		res = FillStopBuffer(BufferNum);
		if ((res & 3) != SONG_ERROR)
		{
			EndQueued = 2;
		}
	}
	else
	{
		res = FillBuffer(BufferNum, MAX_EVENTS, MAX_TIME);
	}
	switch (res & 3)
	{
	case SONG_MORE:
		res = MIDI->StreamOut(&Buffer[BufferNum]);
		if (res != 0)
		{
			return res;
		}
		else
		{
			BufferNum ^= 1;
		}
		break;

	case SONG_DONE:
		if (m_Looping)
		{
			Restarting = true;
			goto fill;
		}
		EndQueued = 1;
		break;

	default:
		return res >> 2;
	}
	return 0;
}

//==========================================================================
//
// MIDIStreamer :: FillBuffer
//
// Copies MIDI events from the MIDI file and puts them into a MIDI stream
// buffer. Filling the buffer stops when the song end is encountered, the
// buffer space is used up, or the maximum time for a buffer is hit.
//
// Can return:
// - SONG_MORE if the buffer was prepared with data.
// - SONG_DONE if the song's end was reached.
//             The buffer will never have data in this case.
// - SONG_ERROR if there was a problem preparing the buffer.
//
//==========================================================================

int MIDIStreamer::FillBuffer(int buffer_num, int max_events, uint32_t max_time)
{
	if (!Restarting && CheckDone())
	{
		return SONG_DONE;
	}

	int i;
	uint32_t *events = Events[buffer_num], *max_event_p;
	uint32_t tot_time = 0;
	uint32_t time = 0;

	// The final event is for a NOP to hold the delay from the last event.
	max_event_p = events + (max_events - 1) * 3;

	if (InitialPlayback)
	{
		InitialPlayback = false;
		// Send the full master volume SysEx message.
		events[0] = 0;								// dwDeltaTime
		events[1] = 0;								// dwStreamID
		events[2] = (MEVENT_LONGMSG << 24) | 8;		// dwEvent
		events[3] = MAKE_ID(0xf0,0x7f,0x7f,0x04);	// dwParms[0]
		events[4] = MAKE_ID(0x01,0x7f,0x7f,0xf7);	// dwParms[1]
		events += 5;
		DoInitialSetup();
	}

	// If the volume has changed, stick those events at the start of this buffer.
	if (VolumeChanged && (m_Status != STATE_Paused || NewVolume == 0))
	{
		VolumeChanged = false;
		for (i = 0; i < 16; ++i)
		{
			uint8_t courseVol = (uint8_t)(((ChannelVolumes[i]+1) * NewVolume) >> 16);
			events[0] = 0;				// dwDeltaTime
			events[1] = 0;				// dwStreamID
			events[2] = MIDI_CTRLCHANGE | i | (7<<8) | (courseVol<<16);
			events += 3;
		}
	}

	// Play nothing while paused.
	if (m_Status == STATE_Paused)
	{
		// Be more responsive when unpausing by only playing each buffer
		// for a third of the maximum time.
		events[0] = MAX<uint32_t>(1, (max_time / 3) * Division / Tempo);
		events[1] = 0;
		events[2] = MEVENT_NOP << 24;
		events += 3;
	}
	else
	{
		if (Restarting)
		{
			Restarting = false;
			// Reset the tempo to the inital value.
			events[0] = 0;									// dwDeltaTime
			events[1] = 0;									// dwStreamID
			events[2] = (MEVENT_TEMPO << 24) | InitialTempo;	// dwEvent
			events += 3;
			// Stop all notes in case any were left hanging.
			events = WriteStopNotes(events);
			DoRestart();
		}
		events = MakeEvents(events, max_event_p, max_time);
	}
	memset(&Buffer[buffer_num], 0, sizeof(MidiHeader));
	Buffer[buffer_num].lpData = (uint8_t *)Events[buffer_num];
	Buffer[buffer_num].dwBufferLength = uint32_t((uint8_t *)events - Buffer[buffer_num].lpData);
	Buffer[buffer_num].dwBytesRecorded = Buffer[buffer_num].dwBufferLength;
	if (0 != (i = MIDI->PrepareHeader(&Buffer[buffer_num])))
	{
		return SONG_ERROR | (i << 2);
	}
	return SONG_MORE;
}

//==========================================================================
//
// MIDIStreamer :: FillStopBuffer
//
// Fills a MIDI buffer with events to stop all channels.
//
//==========================================================================

int MIDIStreamer::FillStopBuffer(int buffer_num)
{
	uint32_t *events = Events[buffer_num];
	int i;

	events = WriteStopNotes(events);

	// wait some tics, just so that this buffer takes some time
	events[0] = 500;
	events[1] = 0;
	events[2] = MEVENT_NOP << 24;
	events += 3;

	memset(&Buffer[buffer_num], 0, sizeof(MidiHeader));
	Buffer[buffer_num].lpData = (uint8_t*)Events[buffer_num];
	Buffer[buffer_num].dwBufferLength = uint32_t((uint8_t*)events - Buffer[buffer_num].lpData);
	Buffer[buffer_num].dwBytesRecorded = Buffer[buffer_num].dwBufferLength;
	if (0 != (i = MIDI->PrepareHeader(&Buffer[buffer_num])))
	{
		return SONG_ERROR | (i << 2);
	}
	return SONG_MORE;
}

//==========================================================================
//
// MIDIStreamer :: WriteStopNotes
//
// Generates MIDI events to stop all notes and reset controllers on
// every channel.
//
//==========================================================================

uint32_t *MIDIStreamer::WriteStopNotes(uint32_t *events)
{
	for (int i = 0; i < 16; ++i)
	{
		events[0] = 0;				// dwDeltaTime
		events[1] = 0;				// dwStreamID
		events[2] = MIDI_CTRLCHANGE | i | (123 << 8);	// All notes off
		events[3] = 0;
		events[4] = 0;
		events[5] = MIDI_CTRLCHANGE | i | (121 << 8);	// Reset controllers
		events += 6;
	}
	return events;
}

//==========================================================================
//
// MIDIStreamer :: Precache
//
// Generates a list of instruments this song uses and passes them to the
// MIDI device for precaching. The default implementation here pretends to
// play the song and watches for program change events on normal channels
// and note on events on channel 10.
//
//==========================================================================

void MIDIStreamer::Precache()
{
	uint8_t found_instruments[256] = { 0, };
	uint8_t found_banks[256] = { 0, };
	bool multiple_banks = false;

	LoopLimit = 1;
	DoRestart();
	found_banks[0] = true;		// Bank 0 is always used.
	found_banks[128] = true;

	// Simulate playback to pick out used instruments.
	while (!CheckDone())
	{
		uint32_t *event_end = MakeEvents(Events[0], &Events[0][MAX_EVENTS*3], 1000000*600);
		for (uint32_t *event = Events[0]; event < event_end; )
		{
			if (MEVENT_EVENTTYPE(event[2]) == 0)
			{
				int command = (event[2] & 0x70);
				int channel = (event[2] & 0x0f);
				int data1 = (event[2] >> 8) & 0x7f;
				int data2 = (event[2] >> 16) & 0x7f;

				if (channel != 9 && command == (MIDI_PRGMCHANGE & 0x70))
				{
					found_instruments[data1] = true;
				}
				else if (channel == 9 && command == (MIDI_PRGMCHANGE & 0x70) && data1 != 0)
				{ // On a percussion channel, program change also serves as bank select.
					multiple_banks = true;
					found_banks[data1 | 128] = true;
				}
				else if (channel == 9 && command == (MIDI_NOTEON & 0x70) && data2 != 0)
				{
					found_instruments[data1 | 128] = true;
				}
				else if (command == (MIDI_CTRLCHANGE & 0x70) && data1 == 0 && data2 != 0)
				{
					multiple_banks = true;
					if (channel == 9)
					{
						found_banks[data2 | 128] = true;
					}
					else
					{
						found_banks[data2] = true;
					}
				}
			}
			// Advance to next event
			if (event[2] < 0x80000000)
			{ // short message
				event += 3;
			}
			else
			{ // long message
				event += 3 + ((MEVENT_EVENTPARM(event[2]) + 3) >> 2);
			}
		}
	}
	DoRestart();

	// Now pack everything into a contiguous region for the PrecacheInstruments call().
	TArray<uint16_t> packed;

	for (int i = 0; i < 256; ++i)
	{
		if (found_instruments[i])
		{
			uint16_t packnum = (i & 127) | ((i & 128) << 7);
			if (!multiple_banks)
			{
				packed.Push(packnum);
			}
			else
			{ // In order to avoid having to multiplex tracks in a type 1 file,
			  // precache every used instrument in every used bank, even if not
			  // all combinations are actually used.
				for (int j = 0; j < 128; ++j)
				{
					if (found_banks[j + (i & 128)])
					{
						packed.Push(packnum | (j << 7));
					}
				}
			}
		}
	}
	MIDI->PrecacheInstruments(&packed[0], packed.Size());
}

//==========================================================================
//
// MIDIStreamer :: CreateSMF
//
// Simulates playback to create a Standard MIDI File.
//
//==========================================================================

void MIDIStreamer::CreateSMF(TArray<uint8_t> &file, int looplimit)
{
	uint32_t delay = 0;
	uint8_t running_status = 255;

	// Always create songs aimed at GM devices.
	CheckCaps(MIDIDEV_MIDIPORT);
	LoopLimit = looplimit <= 0 ? EXPORT_LOOP_LIMIT : looplimit;
	DoRestart();
	Tempo = InitialTempo;

	file.Reserve(sizeof(StaticMIDIhead));
	memcpy(&file[0], StaticMIDIhead, sizeof(StaticMIDIhead));
	file[12] = Division >> 8;
	file[13] = Division & 0xFF;
	file[26] = InitialTempo >> 16;
	file[27] = InitialTempo >> 8;
	file[28] = InitialTempo;

	while (!CheckDone())
	{
		uint32_t *event_end = MakeEvents(Events[0], &Events[0][MAX_EVENTS*3], 1000000*600);
		for (uint32_t *event = Events[0]; event < event_end; )
		{
			delay += event[0];
			if (MEVENT_EVENTTYPE(event[2]) == MEVENT_TEMPO)
			{
				WriteVarLen(file, delay);
				delay = 0;
				uint32_t tempo = MEVENT_EVENTPARM(event[2]);
				file.Push(MIDI_META);
				file.Push(MIDI_META_TEMPO);
				file.Push(3);
				file.Push(uint8_t(tempo >> 16));
				file.Push(uint8_t(tempo >> 8));
				file.Push(uint8_t(tempo));
				running_status = 255;
			}
			else if (MEVENT_EVENTTYPE(event[2]) == MEVENT_LONGMSG)
			{
				WriteVarLen(file, delay);
				delay = 0;
				uint32_t len = MEVENT_EVENTPARM(event[2]);
				uint8_t *bytes = (uint8_t *)&event[3];
				if (bytes[0] == MIDI_SYSEX)
				{
					len--;
					file.Push(MIDI_SYSEX);
					WriteVarLen(file, len);
					memcpy(&file[file.Reserve(len)], bytes + 1, len);
				}
				else
				{
					file.Push(MIDI_SYSEXEND);
					WriteVarLen(file, len);
					memcpy(&file[file.Reserve(len)], bytes, len);
				}
				running_status = 255;
			}
			else if (MEVENT_EVENTTYPE(event[2]) == 0)
			{
				WriteVarLen(file, delay);
				delay = 0;
				uint8_t status = uint8_t(event[2]);
				if (status != running_status)
				{
					running_status = status;
					file.Push(status);
				}
				file.Push(uint8_t((event[2] >> 8) & 0x7F));
				if (MIDI_EventLengths[(status >> 4) & 7] == 2)
				{
					file.Push(uint8_t((event[2] >> 16) & 0x7F));
				}
			}
			// Advance to next event
			if (event[2] < 0x80000000)
			{ // short message
				event += 3;
			}
			else
			{ // long message
				event += 3 + ((MEVENT_EVENTPARM(event[2]) + 3) >> 2);
			}
		}
	}

	// End track
	WriteVarLen(file, delay);
	file.Push(MIDI_META);
	file.Push(MIDI_META_EOT);
	file.Push(0);

	// Fill in track length
	uint32_t len = file.Size() - 22;
	file[18] = uint8_t(len >> 24);
	file[19] = uint8_t(len >> 16);
	file[20] = uint8_t(len >> 8);
	file[21] = uint8_t(len & 255);

	LoopLimit = 0;
}

//==========================================================================
//
// WriteVarLen
//
//==========================================================================

static void WriteVarLen (TArray<uint8_t> &file, uint32_t value)
{
   uint32_t buffer = value & 0x7F;

   while ( (value >>= 7) )
   {
     buffer <<= 8;
     buffer |= (value & 0x7F) | 0x80;
   }

   for (;;)
   {
	   file.Push(uint8_t(buffer));
	   if (buffer & 0x80)
	   {
		   buffer >>= 8;
	   }
	   else
	   {
		   break;
	   }
   }
}

//==========================================================================
//
// MIDIStreamer :: SetTempo
//
// Sets the tempo from a track's initial meta events. Later tempo changes
// create MEVENT_TEMPO events instead.
//
//==========================================================================

void MIDIStreamer::SetTempo(int new_tempo)
{
	InitialTempo = new_tempo;
	if (NULL != MIDI && 0 == MIDI->SetTempo(new_tempo))
	{
		Tempo = new_tempo;
	}
}


//==========================================================================
//
// MIDIStreamer :: ClampLoopCount
//
// We use the XMIDI interpretation of loop count here, where 1 means it
// plays that section once (in other words, no loop) rather than the EMIDI
// interpretation where 1 means to loop it once.
//
// If LoopLimit is 1, we limit all loops, since this pass over the song is
// used to determine instruments for precaching.
//
// If LoopLimit is higher, we only limit infinite loops, since this song is
// being exported.
//
//==========================================================================

int MIDIStreamer::ClampLoopCount(int loopcount)
{
	if (LoopLimit == 0)
	{
		return loopcount;
	}
	if (LoopLimit == 1)
	{
		return 1;
	}
	if (loopcount == 0)
	{
		return LoopLimit;
	}
	return loopcount;
}

//==========================================================================
//
// MIDIStreamer :: GetStats
//
//==========================================================================

FString MIDIStreamer::GetStats()
{
	if (MIDI == NULL)
	{
		return "No MIDI device in use.";
	}
	return MIDI->GetStats();
}

//==========================================================================
//
// MIDIStreamer :: SetSubsong
//
// Selects which subsong to play in an already-playing file. This is public.
//
//==========================================================================

bool MIDIStreamer::SetSubsong(int subsong)
{
	if (SetMIDISubsong(subsong))
	{
		Stop();
		Play(m_Looping, subsong);
		return true;
	}
	return false;
}

//==========================================================================
//
// MIDIStreamer :: SetMIDISubsong
//
// Selects which subsong to play. This is private.
//
//==========================================================================

bool MIDIStreamer::SetMIDISubsong(int subsong)
{
	return subsong == 0;
}

//==========================================================================
//
// MIDIDevice stubs.
//
//==========================================================================

MIDIDevice::MIDIDevice()
{
}

MIDIDevice::~MIDIDevice()
{
}

//==========================================================================
//
// MIDIDevice :: PrecacheInstruments
//
// The MIDIStreamer calls this method between device open and the first
// buffered stream with a list of instruments known to be used by the song.
// If the device can benefit from preloading the instruments, it can do so
// now.
//
// Each entry is packed as follows:
//   Bits 0- 6: Instrument number
//   Bits 7-13: Bank number
//   Bit    14: Select drum set if 1, tone bank if 0
//
//==========================================================================

void MIDIDevice::PrecacheInstruments(const uint16_t *instruments, int count)
{
}

//==========================================================================
//
// MIDIDevice :: Preprocess
//
// Gives the MIDI device a chance to do some processing with the song before
// it starts playing it. Returns true if MIDIStreamer should perform its
// standard playback startup sequence.
//
//==========================================================================

bool MIDIDevice::Preprocess(MIDIStreamer *song, bool looping)
{
	return true;
}

//==========================================================================
//
// MIDIDevice :: PrepareHeader
//
// Wrapper for MCI's midiOutPrepareHeader.
//
//==========================================================================

int MIDIDevice::PrepareHeader(MidiHeader *header)
{
	return 0;
}

//==========================================================================
//
// MIDIDevice :: UnprepareHeader
//
// Wrapper for MCI's midiOutUnprepareHeader.
//
//==========================================================================

int MIDIDevice::UnprepareHeader(MidiHeader *header)
{
	return 0;
}

//==========================================================================
//
// MIDIDevice :: FakeVolume
//
// Since most implementations render as a normal stream, their volume is
// controlled through the GSnd interface, not here.
//
//==========================================================================

bool MIDIDevice::FakeVolume()
{
	return false;
}

//==========================================================================
//
//
//
//==========================================================================

void MIDIDevice::InitPlayback()
{
}

//==========================================================================
//
//
//
//==========================================================================

bool MIDIDevice::Update()
{
	return true;
}

//==========================================================================
//
// MIDIDevice :: TimidityVolumeChanged
//
//==========================================================================

void MIDIDevice::TimidityVolumeChanged()
{
}

//==========================================================================
//
// MIDIDevice :: FluidSettingInt
//
//==========================================================================

void MIDIDevice::FluidSettingInt(const char *setting, int value)
{
}

//==========================================================================
//
// MIDIDevice :: FluidSettingNum
//
//==========================================================================

void MIDIDevice::FluidSettingNum(const char *setting, double value)
{
}

//==========================================================================
//
// MIDIDevice :: FluidSettingStr
//
//==========================================================================

void MIDIDevice::FluidSettingStr(const char *setting, const char *value)
{
}

//==========================================================================
//
// MIDIDevice :: WildMidiSetOption
//
//==========================================================================

void MIDIDevice::WildMidiSetOption(int opt, int set)
{
}

//==========================================================================
//
// MIDIDevice :: GetStats
//
//==========================================================================

FString MIDIDevice::GetStats()
{
	return "This MIDI device does not have any stats.";
}