Update: Translations from eints

[openttd-github.git] / src / music / dmusic.cpp

/*
 * This file is part of OpenTTD.
 * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
 * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
 */

/** @file dmusic.cpp Playing music via DirectMusic. */

#define INITGUID
#include "../stdafx.h"
#ifdef WIN32_LEAN_AND_MEAN
#       undef WIN32_LEAN_AND_MEAN // Don't exclude rarely-used stuff from Windows headers
#endif
#include "../debug.h"
#include "../os/windows/win32.h"
#include "../core/mem_func.hpp"
#include "../thread.h"
#include "../fileio_func.h"
#include "../base_media_base.h"
#include "dmusic.h"
#include "midifile.hpp"
#include "midi.h"

#include <windows.h>
#include <dmksctrl.h>
#include <dmusicc.h>
#include <mutex>

#include "../safeguards.h"

#if defined(_MSC_VER)
#       pragma comment(lib, "ole32.lib")
#endif /* defined(_MSC_VER) */

static const int MS_TO_REFTIME = 1000 * 10; ///< DirectMusic time base is 100 ns.
static const int MIDITIME_TO_REFTIME = 10;  ///< Time base of the midi file reader is 1 us.


#define FOURCC_INFO  mmioFOURCC('I', 'N', 'F', 'O')
#define FOURCC_fmt   mmioFOURCC('f', 'm', 't', ' ')
#define FOURCC_data  mmioFOURCC('d', 'a', 't', 'a')

/** A DLS file. */
struct DLSFile {
        /** An instrument region maps a note range to wave data. */
        struct DLSRegion {
                RGNHEADER hdr;
                WAVELINK wave;
                WSMPL wave_sample;

                std::vector<WLOOP> wave_loops;
                std::vector<CONNECTION> articulators;
        };

        /** Instrument definition read from a DLS file. */
        struct DLSInstrument {
                INSTHEADER hdr;

                std::vector<CONNECTION> articulators;
                std::vector<DLSRegion> regions;
        };

        /** Wave data definition from a DLS file. */
        struct DLSWave {
                long file_offset;

                PCMWAVEFORMAT fmt;
                std::vector<BYTE> data;

                WSMPL wave_sample;
                std::vector<WLOOP> wave_loops;
        };

        std::vector<DLSInstrument> instruments;
        std::vector<POOLCUE> pool_cues;
        std::vector<DLSWave> waves;

        /** Try loading a DLS file into memory. */
        bool LoadFile(const std::string &file);

private:
        /** Load an articulation structure from a DLS file. */
        bool ReadDLSArticulation(FileHandle &f, DWORD list_length, std::vector<CONNECTION> &out);
        /** Load a list of regions from a DLS file. */
        bool ReadDLSRegionList(FileHandle &f, DWORD list_length, DLSInstrument &instrument);
        /** Load a single region from a DLS file. */
        bool ReadDLSRegion(FileHandle &f, DWORD list_length, std::vector<DLSRegion> &out);
        /** Load a list of instruments from a DLS file. */
        bool ReadDLSInstrumentList(FileHandle &f, DWORD list_length);
        /** Load a single instrument from a DLS file. */
        bool ReadDLSInstrument(FileHandle &f, DWORD list_length);
        /** Load a list of waves from a DLS file. */
        bool ReadDLSWaveList(FileHandle &f, DWORD list_length);
        /** Load a single wave from a DLS file. */
        bool ReadDLSWave(FileHandle &f, DWORD list_length, long offset);
};

/** A RIFF chunk header. */
PACK_N(struct ChunkHeader {
        FOURCC type;  ///< Chunk type.
        DWORD length; ///< Length of the chunk, not including the chunk header itself.
}, 2);

/** Buffer format for a DLS wave download. */
PACK_N(struct WAVE_DOWNLOAD {
        DMUS_DOWNLOADINFO   dlInfo;
        ULONG               ulOffsetTable[2];
        DMUS_WAVE           dmWave;
        DMUS_WAVEDATA       dmWaveData;
}, 2);

struct PlaybackSegment {
        uint32_t start, end;
        size_t start_block;
        bool loop;
};

static struct {
        bool shutdown;    ///< flag to indicate playback thread shutdown
        bool playing;     ///< flag indicating that playback is active
        bool do_start;    ///< flag for starting playback of next_file at next opportunity
        bool do_stop;     ///< flag for stopping playback at next opportunity

        int preload_time; ///< preload time for music blocks.
        uint8_t new_volume;  ///< volume setting to change to

        MidiFile next_file;           ///< upcoming file to play
        PlaybackSegment next_segment; ///< segment info for upcoming file
} _playback;

/** Handle to our worker thread. */
static std::thread _dmusic_thread;
/** Event to signal the thread that it should look at a state change. */
static HANDLE _thread_event = nullptr;
/** Lock access to playback data that is not thread-safe. */
static std::mutex _thread_mutex;

/** The direct music object manages buffers and ports. */
static IDirectMusic *_music = nullptr;
/** The port object lets us send MIDI data to the synthesizer. */
static IDirectMusicPort *_port = nullptr;
/** The buffer object collects the data to sent. */
static IDirectMusicBuffer *_buffer = nullptr;
/** List of downloaded DLS instruments. */
static std::vector<IDirectMusicDownload *> _dls_downloads;


static FMusicDriver_DMusic iFMusicDriver_DMusic;


bool DLSFile::ReadDLSArticulation(FileHandle &f, DWORD list_length, std::vector<CONNECTION> &out)
{
        while (list_length > 0) {
                ChunkHeader chunk;
                if (fread(&chunk, sizeof(chunk), 1, f) != 1) return false;
                list_length -= chunk.length + sizeof(chunk);

                if (chunk.type == FOURCC_ART1) {
                        CONNECTIONLIST conns;
                        if (fread(&conns, sizeof(conns), 1, f) != 1) return false;
                        fseek(f, conns.cbSize - sizeof(conns), SEEK_CUR);

                        /* Read all defined articulations. */
                        for (ULONG i = 0; i < conns.cConnections; i++) {
                                CONNECTION con;
                                if (fread(&con, sizeof(con), 1, f) != 1) return false;
                                out.push_back(con);
                        }
                } else {
                        fseek(f, chunk.length, SEEK_CUR);
                }
        }

        return true;
}

bool DLSFile::ReadDLSRegion(FileHandle &f, DWORD list_length, std::vector<DLSRegion> &out)
{
        DLSRegion &region = out.emplace_back();

        /* Set default values. */
        region.wave_sample.cbSize = 0;

        while (list_length > 0) {
                ChunkHeader chunk;
                if (fread(&chunk, sizeof(chunk), 1, f) != 1) return false;
                list_length -= chunk.length + sizeof(chunk);

                if (chunk.type == FOURCC_LIST) {
                        /* Unwrap list header. */
                        if (fread(&chunk.type, sizeof(chunk.type), 1, f) != 1) return false;
                        chunk.length -= sizeof(chunk.type);
                }

                switch (chunk.type) {
                        case FOURCC_RGNH:
                                if (fread(&region.hdr, sizeof(region.hdr), 1, f) != 1) return false;
                                break;

                        case FOURCC_WSMP:
                                if (fread(&region.wave_sample, sizeof(region.wave_sample), 1, f) != 1) return false;
                                fseek(f, region.wave_sample.cbSize - sizeof(region.wave_sample), SEEK_CUR);

                                /* Read all defined sample loops. */
                                for (ULONG i = 0; i < region.wave_sample.cSampleLoops; i++) {
                                        WLOOP loop;
                                        if (fread(&loop, sizeof(loop), 1, f) != 1) return false;
                                        region.wave_loops.push_back(loop);
                                }
                                break;

                        case FOURCC_WLNK:
                                if (fread(&region.wave, sizeof(region.wave), 1, f) != 1) return false;
                                break;

                        case FOURCC_LART: // List chunk
                                if (!this->ReadDLSArticulation(f, chunk.length, region.articulators)) return false;
                                break;

                        case FOURCC_INFO:
                                /* We don't care about info stuff. */
                                fseek(f, chunk.length, SEEK_CUR);
                                break;

                        default:
                                Debug(driver, 7, "DLS: Ignoring unknown chunk {}{}{}{}", (char)(chunk.type & 0xFF), (char)((chunk.type >> 8) & 0xFF), (char)((chunk.type >> 16) & 0xFF), (char)((chunk.type >> 24) & 0xFF));
                                fseek(f, chunk.length, SEEK_CUR);
                                break;
                }
        }

        return true;
}

bool DLSFile::ReadDLSRegionList(FileHandle &f, DWORD list_length, DLSInstrument &instrument)
{
        while (list_length > 0) {
                ChunkHeader chunk;
                if (fread(&chunk, sizeof(chunk), 1, f) != 1) return false;
                list_length -= chunk.length + sizeof(chunk);

                if (chunk.type == FOURCC_LIST) {
                        FOURCC list_type;
                        if (fread(&list_type, sizeof(list_type), 1, f) != 1) return false;

                        if (list_type == FOURCC_RGN) {
                                this->ReadDLSRegion(f, chunk.length - sizeof(list_type), instrument.regions);
                        } else {
                                Debug(driver, 7, "DLS: Ignoring unknown list chunk of type {}{}{}{}", (char)(list_type & 0xFF), (char)((list_type >> 8) & 0xFF), (char)((list_type >> 16) & 0xFF), (char)((list_type >> 24) & 0xFF));
                                fseek(f, chunk.length - sizeof(list_type), SEEK_CUR);
                        }
                } else {
                        Debug(driver, 7, "DLS: Ignoring chunk {}{}{}{}", (char)(chunk.type & 0xFF), (char)((chunk.type >> 8) & 0xFF), (char)((chunk.type >> 16) & 0xFF), (char)((chunk.type >> 24) & 0xFF));
                        fseek(f, chunk.length, SEEK_CUR);
                }
        }

        return true;
}

bool DLSFile::ReadDLSInstrument(FileHandle &f, DWORD list_length)
{
        DLSInstrument &instrument = this->instruments.emplace_back();

        while (list_length > 0) {
                ChunkHeader chunk;
                if (fread(&chunk, sizeof(chunk), 1, f) != 1) return false;
                list_length -= chunk.length + sizeof(chunk);

                if (chunk.type == FOURCC_LIST) {
                        /* Unwrap list header. */
                        if (fread(&chunk.type, sizeof(chunk.type), 1, f) != 1) return false;
                        chunk.length -= sizeof(chunk.type);
                }

                switch (chunk.type) {
                        case FOURCC_INSH:
                                if (fread(&instrument.hdr, sizeof(instrument.hdr), 1, f) != 1) return false;
                                break;

                        case FOURCC_LART: // List chunk
                                if (!this->ReadDLSArticulation(f, chunk.length, instrument.articulators)) return false;
                                break;

                        case FOURCC_LRGN: // List chunk
                                if (!this->ReadDLSRegionList(f, chunk.length, instrument)) return false;
                                break;

                        case FOURCC_INFO:
                                /* We don't care about info stuff. */
                                fseek(f, chunk.length, SEEK_CUR);
                                break;

                        default:
                                Debug(driver, 7, "DLS: Ignoring unknown chunk {}{}{}{}", (char)(chunk.type & 0xFF), (char)((chunk.type >> 8) & 0xFF), (char)((chunk.type >> 16) & 0xFF), (char)((chunk.type >> 24) & 0xFF));
                                fseek(f, chunk.length, SEEK_CUR);
                                break;
                }
        }

        return true;
}

bool DLSFile::ReadDLSInstrumentList(FileHandle &f, DWORD list_length)
{
        while (list_length > 0) {
                ChunkHeader chunk;
                if (fread(&chunk, sizeof(chunk), 1, f) != 1) return false;
                list_length -= chunk.length + sizeof(chunk);

                if (chunk.type == FOURCC_LIST) {
                        FOURCC list_type;
                        if (fread(&list_type, sizeof(list_type), 1, f) != 1) return false;

                        if (list_type == FOURCC_INS) {
                                Debug(driver, 6, "DLS: Reading instrument {}", (int)instruments.size());

                                if (!this->ReadDLSInstrument(f, chunk.length - sizeof(list_type))) return false;
                        } else {
                                Debug(driver, 7, "DLS: Ignoring unknown list chunk of type {}{}{}{}", (char)(list_type & 0xFF), (char)((list_type >> 8) & 0xFF), (char)((list_type >> 16) & 0xFF), (char)((list_type >> 24) & 0xFF));
                                fseek(f, chunk.length - sizeof(list_type), SEEK_CUR);
                        }
                } else {
                        Debug(driver, 7, "DLS: Ignoring chunk {}{}{}{}", (char)(chunk.type & 0xFF), (char)((chunk.type >> 8) & 0xFF), (char)((chunk.type >> 16) & 0xFF), (char)((chunk.type >> 24) & 0xFF));
                        fseek(f, chunk.length, SEEK_CUR);
                }
        }

        return true;
}

bool DLSFile::ReadDLSWave(FileHandle &f, DWORD list_length, long offset)
{
        DLSWave &wave = this->waves.emplace_back();

        /* Set default values. */
        MemSetT(&wave.wave_sample, 0);
        wave.wave_sample.cbSize = sizeof(WSMPL);
        wave.wave_sample.usUnityNote = 60;
        wave.file_offset = offset; // Store file offset so we can resolve the wave pool table later on.

        while (list_length > 0) {
                ChunkHeader chunk;
                if (fread(&chunk, sizeof(chunk), 1, f) != 1) return false;
                list_length -= chunk.length + sizeof(chunk);

                if (chunk.type == FOURCC_LIST) {
                        /* Unwrap list header. */
                        if (fread(&chunk.type, sizeof(chunk.type), 1, f) != 1) return false;
                        chunk.length -= sizeof(chunk.type);
                }

                switch (chunk.type) {
                        case FOURCC_fmt:
                                if (fread(&wave.fmt, sizeof(wave.fmt), 1, f) != 1) return false;
                                if (chunk.length > sizeof(wave.fmt)) fseek(f, chunk.length - sizeof(wave.fmt), SEEK_CUR);
                                break;

                        case FOURCC_WSMP:
                                if (fread(&wave.wave_sample, sizeof(wave.wave_sample), 1, f) != 1) return false;
                                fseek(f, wave.wave_sample.cbSize - sizeof(wave.wave_sample), SEEK_CUR);

                                /* Read all defined sample loops. */
                                for (ULONG i = 0; i < wave.wave_sample.cSampleLoops; i++) {
                                        WLOOP loop;
                                        if (fread(&loop, sizeof(loop), 1, f) != 1) return false;
                                        wave.wave_loops.push_back(loop);
                                }
                                break;

                        case FOURCC_data:
                                wave.data.resize(chunk.length);
                                if (fread(&wave.data[0], sizeof(BYTE), wave.data.size(), f) != wave.data.size()) return false;
                                break;

                        case FOURCC_INFO:
                                /* We don't care about info stuff. */
                                fseek(f, chunk.length, SEEK_CUR);
                                break;

                        default:
                                Debug(driver, 7, "DLS: Ignoring unknown chunk {}{}{}{}", (char)(chunk.type & 0xFF), (char)((chunk.type >> 8) & 0xFF), (char)((chunk.type >> 16) & 0xFF), (char)((chunk.type >> 24) & 0xFF));
                                fseek(f, chunk.length, SEEK_CUR);
                                break;
                }
        }

        return true;
}

bool DLSFile::ReadDLSWaveList(FileHandle &f, DWORD list_length)
{
        long base_offset = ftell(f);

        while (list_length > 0) {
                long chunk_offset = ftell(f);

                ChunkHeader chunk;
                if (fread(&chunk, sizeof(chunk), 1, f) != 1) return false;
                list_length -= chunk.length + sizeof(chunk);

                if (chunk.type == FOURCC_LIST) {
                        FOURCC list_type;
                        if (fread(&list_type, sizeof(list_type), 1, f) != 1) return false;

                        if (list_type == FOURCC_wave) {
                                Debug(driver, 6, "DLS: Reading wave {}", waves.size());

                                if (!this->ReadDLSWave(f, chunk.length - sizeof(list_type), chunk_offset - base_offset)) return false;
                        } else {
                                Debug(driver, 7, "DLS: Ignoring unknown list chunk of type {}{}{}{}", (char)(list_type & 0xFF), (char)((list_type >> 8) & 0xFF), (char)((list_type >> 16) & 0xFF), (char)((list_type >> 24) & 0xFF));
                                fseek(f, chunk.length - sizeof(list_type), SEEK_CUR);
                        }
                } else {
                        Debug(driver, 7, "DLS: Ignoring chunk {}{}{}{}", (char)(chunk.type & 0xFF), (char)((chunk.type >> 8) & 0xFF), (char)((chunk.type >> 16) & 0xFF), (char)((chunk.type >> 24) & 0xFF));
                        fseek(f, chunk.length, SEEK_CUR);
                }
        }

        return true;
}

bool DLSFile::LoadFile(const std::string &file)
{
        Debug(driver, 2, "DMusic: Try to load DLS file {}", file);

        auto of = FileHandle::Open(file, "rb");
        if (!of.has_value()) return false;
        auto &f = *of;

        /* Check DLS file header. */
        ChunkHeader hdr;
        FOURCC dls_type;
        if (fread(&hdr, sizeof(hdr), 1, f) != 1) return false;
        if (fread(&dls_type, sizeof(dls_type), 1, f) != 1) return false;
        if (hdr.type != FOURCC_RIFF || dls_type != FOURCC_DLS) return false;

        hdr.length -= sizeof(FOURCC);

        Debug(driver, 2, "DMusic: Parsing DLS file");

        DLSHEADER header;
        MemSetT(&header, 0);

        /* Iterate over all chunks in the file. */
        while (hdr.length > 0) {
                ChunkHeader chunk;
                if (fread(&chunk, sizeof(chunk), 1, f) != 1) return false;
                hdr.length -= chunk.length + sizeof(chunk);

                if (chunk.type == FOURCC_LIST) {
                        /* Unwrap list header. */
                        if (fread(&chunk.type, sizeof(chunk.type), 1, f) != 1) return false;
                        chunk.length -= sizeof(chunk.type);
                }

                switch (chunk.type) {
                        case FOURCC_COLH:
                                if (fread(&header, sizeof(header), 1, f) != 1) return false;
                                break;

                        case FOURCC_LINS: // List chunk
                                if (!this->ReadDLSInstrumentList(f, chunk.length)) return false;
                                break;

                        case FOURCC_WVPL: // List chunk
                                if (!this->ReadDLSWaveList(f, chunk.length)) return false;
                                break;

                        case FOURCC_PTBL:
                                POOLTABLE ptbl;
                                if (fread(&ptbl, sizeof(ptbl), 1, f) != 1) return false;
                                fseek(f, ptbl.cbSize - sizeof(ptbl), SEEK_CUR);

                                /* Read all defined cues. */
                                for (ULONG i = 0; i < ptbl.cCues; i++) {
                                        POOLCUE cue;
                                        if (fread(&cue, sizeof(cue), 1, f) != 1) return false;
                                        this->pool_cues.push_back(cue);
                                }
                                break;

                        case FOURCC_INFO:
                                /* We don't care about info stuff. */
                                fseek(f, chunk.length, SEEK_CUR);
                                break;

                        default:
                                Debug(driver, 7, "DLS: Ignoring unknown chunk {}{}{}{}", (char)(chunk.type & 0xFF), (char)((chunk.type >> 8) & 0xFF), (char)((chunk.type >> 16) & 0xFF), (char)((chunk.type >> 24) & 0xFF));
                                fseek(f, chunk.length, SEEK_CUR);
                                break;
                }
        }

        /* Have we read as many instruments as indicated? */
        if (header.cInstruments != this->instruments.size()) return false;

        /* Resolve wave pool table. */
        for (std::vector<POOLCUE>::iterator cue = this->pool_cues.begin(); cue != this->pool_cues.end(); cue++) {
                std::vector<DLSWave>::iterator w = std::ranges::find(this->waves, cue->ulOffset, &DLSWave::file_offset);
                if (w != this->waves.end()) {
                        cue->ulOffset = (ULONG)(w - this->waves.begin());
                } else {
                        cue->ulOffset = 0;
                }
        }

        return true;
}


static uint8_t ScaleVolume(uint8_t original, uint8_t scale)
{
        return original * scale / 127;
}

static void TransmitChannelMsg(IDirectMusicBuffer *buffer, REFERENCE_TIME rt, uint8_t status, uint8_t p1, uint8_t p2 = 0)
{
        if (buffer->PackStructured(rt, 0, status | (p1 << 8) | (p2 << 16)) == E_OUTOFMEMORY) {
                /* Buffer is full, clear it and try again. */
                _port->PlayBuffer(buffer);
                buffer->Flush();

                buffer->PackStructured(rt, 0, status | (p1 << 8) | (p2 << 16));
        }
}

static void TransmitSysex(IDirectMusicBuffer *buffer, REFERENCE_TIME rt, const uint8_t *&msg_start, size_t &remaining)
{
        /* Find end of message. */
        const uint8_t *msg_end = msg_start;
        while (*msg_end != MIDIST_ENDSYSEX) msg_end++;
        msg_end++; // Also include SysEx end byte.

        if (buffer->PackUnstructured(rt, 0, msg_end - msg_start, const_cast<LPBYTE>(msg_start)) == E_OUTOFMEMORY) {
                /* Buffer is full, clear it and try again. */
                _port->PlayBuffer(buffer);
                buffer->Flush();

                buffer->PackUnstructured(rt, 0, msg_end - msg_start, const_cast<LPBYTE>(msg_start));
        }

        /* Update position in buffer. */
        remaining -= msg_end - msg_start;
        msg_start = msg_end;
}

static void TransmitStandardSysex(IDirectMusicBuffer *buffer, REFERENCE_TIME rt, MidiSysexMessage msg)
{
        size_t length = 0;
        const uint8_t *data = MidiGetStandardSysexMessage(msg, length);
        TransmitSysex(buffer, rt, data, length);
}

/** Transmit 'Note off' messages to all MIDI channels. */
static void TransmitNotesOff(IDirectMusicBuffer *buffer, REFERENCE_TIME block_time, REFERENCE_TIME cur_time)
{
        for (int ch = 0; ch < 16; ch++) {
                TransmitChannelMsg(buffer, block_time + 10, MIDIST_CONTROLLER | ch, MIDICT_MODE_ALLNOTESOFF, 0);
                TransmitChannelMsg(buffer, block_time + 10, MIDIST_CONTROLLER | ch, MIDICT_SUSTAINSW, 0);
                TransmitChannelMsg(buffer, block_time + 10, MIDIST_CONTROLLER | ch, MIDICT_MODE_RESETALLCTRL, 0);
        }

        /* Performing a GM reset stops all sound and resets all parameters. */
        TransmitStandardSysex(buffer, block_time + 20, MidiSysexMessage::ResetGM);
        TransmitStandardSysex(buffer, block_time + 30, MidiSysexMessage::RolandSetReverb);

        /* Explicitly flush buffer to make sure the messages are processed,
         * as we want sound to stop immediately. */
        _port->PlayBuffer(buffer);
        buffer->Flush();

        /* Wait until message time has passed. */
        Sleep(Clamp((block_time - cur_time) / MS_TO_REFTIME, 5, 1000));
}

static void MidiThreadProc()
{
        Debug(driver, 2, "DMusic: Entering playback thread");

        REFERENCE_TIME last_volume_time = 0; // timestamp of the last volume change
        REFERENCE_TIME block_time = 0;       // timestamp of the last block sent to the port
        REFERENCE_TIME playback_start_time;  // timestamp current file began playback
        MidiFile current_file;               // file currently being played from
        PlaybackSegment current_segment;     // segment info for current playback
        size_t current_block = 0;            // next block index to send
        uint8_t current_volume = 0;             // current effective volume setting
        uint8_t channel_volumes[16];            // last seen volume controller values in raw data

        /* Get pointer to the reference clock of our output port. */
        IReferenceClock *clock;
        _port->GetLatencyClock(&clock);

        REFERENCE_TIME cur_time;
        clock->GetTime(&cur_time);

        _port->PlayBuffer(_buffer);
        _buffer->Flush();

        DWORD next_timeout = 1000;
        while (true) {
                /* Wait for a signal from the GUI thread or until the time for the next event has come. */
                DWORD wfso = WaitForSingleObject(_thread_event, next_timeout);

                if (_playback.shutdown) {
                        _playback.playing = false;
                        break;
                }

                if (_playback.do_stop) {
                        Debug(driver, 2, "DMusic thread: Stopping playback");

                        /* Turn all notes off and wait a bit to allow the messages to be handled. */
                        clock->GetTime(&cur_time);
                        TransmitNotesOff(_buffer, block_time, cur_time);

                        _playback.playing = false;
                        _playback.do_stop = false;
                        block_time = 0;
                        next_timeout = 1000;
                        continue;
                }

                if (wfso == WAIT_OBJECT_0) {
                        if (_playback.do_start) {
                                Debug(driver, 2, "DMusic thread: Starting playback");
                                {
                                        /* New scope to limit the time the mutex is locked. */
                                        std::lock_guard<std::mutex> lock(_thread_mutex);

                                        current_file.MoveFrom(_playback.next_file);
                                        std::swap(_playback.next_segment, current_segment);
                                        current_segment.start_block = 0;
                                        current_block = 0;
                                        _playback.playing = true;
                                        _playback.do_start = false;
                                }

                                /* Reset playback device between songs. */
                                clock->GetTime(&cur_time);
                                TransmitNotesOff(_buffer, block_time, cur_time);

                                MemSetT<uint8_t>(channel_volumes, 127, lengthof(channel_volumes));
                                /* Invalidate current volume. */
                                current_volume = UINT8_MAX;
                                last_volume_time = 0;

                                /* Take the current time plus the preload time as the music start time. */
                                clock->GetTime(&playback_start_time);
                                playback_start_time += _playback.preload_time * MS_TO_REFTIME;
                        }
                }

                if (_playback.playing) {
                        /* skip beginning of file? */
                        if (current_segment.start > 0 && current_block == 0 && current_segment.start_block == 0) {
                                /* find first block after start time and pretend playback started earlier
                                 * this is to allow all blocks prior to the actual start to still affect playback,
                                 * as they may contain important controller and program changes */
                                size_t preload_bytes = 0;
                                for (size_t bl = 0; bl < current_file.blocks.size(); bl++) {
                                        MidiFile::DataBlock &block = current_file.blocks[bl];
                                        preload_bytes += block.data.size();
                                        if (block.ticktime >= current_segment.start) {
                                                if (current_segment.loop) {
                                                        Debug(driver, 2, "DMusic: timer: loop from block {} (ticktime {}, realtime {:.3f}, bytes {})", bl, block.ticktime, ((int)block.realtime) / 1000.0, preload_bytes);
                                                        current_segment.start_block = bl;
                                                        break;
                                                } else {
                                                        /* Skip the transmission delay compensation performed in the Win32 MIDI driver.
                                                         * The DMusic driver will most likely be used with the MS softsynth, which is not subject to transmission delays.
                                                         */
                                                        Debug(driver, 2, "DMusic: timer: start from block {} (ticktime {}, realtime {:.3f}, bytes {})", bl, block.ticktime, ((int)block.realtime) / 1000.0, preload_bytes);
                                                        playback_start_time -= block.realtime * MIDITIME_TO_REFTIME;
                                                        break;
                                                }
                                        }
                                }
                        }

                        /* Get current playback timestamp. */
                        REFERENCE_TIME current_time;
                        clock->GetTime(&current_time);

                        /* Check for volume change. */
                        if (current_volume != _playback.new_volume) {
                                if (current_time - last_volume_time > 10 * MS_TO_REFTIME) {
                                        Debug(driver, 2, "DMusic thread: volume change");
                                        current_volume = _playback.new_volume;
                                        last_volume_time = current_time;
                                        for (int ch = 0; ch < 16; ch++) {
                                                int vol = ScaleVolume(channel_volumes[ch], current_volume);
                                                TransmitChannelMsg(_buffer, block_time + 1, MIDIST_CONTROLLER | ch, MIDICT_CHANVOLUME, vol);
                                        }
                                        _port->PlayBuffer(_buffer);
                                        _buffer->Flush();
                                }
                        }

                        while (current_block < current_file.blocks.size()) {
                                MidiFile::DataBlock &block = current_file.blocks[current_block];

                                /* check that block isn't at end-of-song override */
                                if (current_segment.end > 0 && block.ticktime >= current_segment.end) {
                                        if (current_segment.loop) {
                                                Debug(driver, 2, "DMusic thread: Looping song");
                                                current_block = current_segment.start_block;
                                                playback_start_time = current_time - current_file.blocks[current_block].realtime * MIDITIME_TO_REFTIME;
                                        } else {
                                                _playback.do_stop = true;
                                        }
                                        next_timeout = 0;
                                        break;
                                }
                                /* check that block is not in the future */
                                REFERENCE_TIME playback_time = current_time - playback_start_time;
                                if (block.realtime * MIDITIME_TO_REFTIME > playback_time +  3 *_playback.preload_time * MS_TO_REFTIME) {
                                        /* Stop the thread loop until we are at the preload time of the next block. */
                                        next_timeout = Clamp(((int64_t)block.realtime * MIDITIME_TO_REFTIME - playback_time) / MS_TO_REFTIME - _playback.preload_time, 0, 1000);
                                        Debug(driver, 9, "DMusic thread: Next event in {} ms (music {}, ref {})", next_timeout, block.realtime * MIDITIME_TO_REFTIME, playback_time);
                                        break;
                                }

                                /* Timestamp of the current block. */
                                block_time = playback_start_time + block.realtime * MIDITIME_TO_REFTIME;
                                Debug(driver, 9, "DMusic thread: Streaming block {} (cur={}, block={})", current_block, (long long)(current_time / MS_TO_REFTIME), (long long)(block_time / MS_TO_REFTIME));

                                const uint8_t *data = block.data.data();
                                size_t remaining = block.data.size();
                                uint8_t last_status = 0;
                                while (remaining > 0) {
                                        /* MidiFile ought to have converted everything out of running status,
                                         * but handle it anyway just to be safe */
                                        uint8_t status = data[0];
                                        if (status & 0x80) {
                                                last_status = status;
                                                data++;
                                                remaining--;
                                        } else {
                                                status = last_status;
                                        }
                                        switch (status & 0xF0) {
                                                case MIDIST_PROGCHG:
                                                case MIDIST_CHANPRESS:
                                                        /* 2 byte channel messages */
                                                        TransmitChannelMsg(_buffer, block_time, status, data[0]);
                                                        data++;
                                                        remaining--;
                                                        break;
                                                case MIDIST_NOTEOFF:
                                                case MIDIST_NOTEON:
                                                case MIDIST_POLYPRESS:
                                                case MIDIST_PITCHBEND:
                                                        /* 3 byte channel messages */
                                                        TransmitChannelMsg(_buffer, block_time, status, data[0], data[1]);
                                                        data += 2;
                                                        remaining -= 2;
                                                        break;
                                                case MIDIST_CONTROLLER:
                                                        /* controller change */
                                                        if (data[0] == MIDICT_CHANVOLUME) {
                                                                /* volume controller, adjust for user volume */
                                                                channel_volumes[status & 0x0F] = data[1];
                                                                int vol = ScaleVolume(data[1], current_volume);
                                                                TransmitChannelMsg(_buffer, block_time, status, data[0], vol);
                                                        } else {
                                                                /* handle other controllers normally */
                                                                TransmitChannelMsg(_buffer, block_time, status, data[0], data[1]);
                                                        }
                                                        data += 2;
                                                        remaining -= 2;
                                                        break;
                                                case 0xF0:
                                                        /* system messages */
                                                        switch (status) {
                                                                case MIDIST_SYSEX: /* system exclusive */
                                                                        TransmitSysex(_buffer, block_time, data, remaining);
                                                                        break;
                                                                case MIDIST_TC_QFRAME: /* time code quarter frame */
                                                                case MIDIST_SONGSEL: /* song select */
                                                                        data++;
                                                                        remaining--;
                                                                        break;
                                                                case MIDIST_SONGPOSPTR: /* song position pointer */
                                                                        data += 2;
                                                                        remaining -= 2;
                                                                        break;
                                                                default: /* remaining have no data bytes */
                                                                        break;
                                                        }
                                                        break;
                                        }
                                }

                                current_block++;
                        }

                        /* Anything in the playback buffer? Send it down the port. */
                        DWORD used_buffer = 0;
                        _buffer->GetUsedBytes(&used_buffer);
                        if (used_buffer > 0) {
                                _port->PlayBuffer(_buffer);
                                _buffer->Flush();
                        }

                        /* end? */
                        if (current_block == current_file.blocks.size()) {
                                if (current_segment.loop) {
                                        current_block = current_segment.start_block;
                                        playback_start_time = block_time - current_file.blocks[current_block].realtime * MIDITIME_TO_REFTIME;
                                } else {
                                        _playback.do_stop = true;
                                }
                                next_timeout = 0;
                        }
                }
        }

        Debug(driver, 2, "DMusic: Exiting playback thread");

        /* Turn all notes off and wait a bit to allow the messages to be handled by real hardware. */
        clock->GetTime(&cur_time);
        TransmitNotesOff(_buffer, block_time, cur_time);
        Sleep(_playback.preload_time * 4);

        clock->Release();
}

static void * DownloadArticulationData(int base_offset, void *data, const std::vector<CONNECTION> &artic)
{
        DMUS_ARTICULATION2 *art = (DMUS_ARTICULATION2 *)data;
        art->ulArtIdx = base_offset + 1;
        art->ulFirstExtCkIdx = 0;
        art->ulNextArtIdx = 0;

        CONNECTIONLIST *con_list = (CONNECTIONLIST *)(art + 1);
        con_list->cbSize = sizeof(CONNECTIONLIST);
        con_list->cConnections = (ULONG)artic.size();
        MemCpyT((CONNECTION *)(con_list + 1), &artic.front(), artic.size());

        return (CONNECTION *)(con_list + 1) + artic.size();
}

static const char *LoadDefaultDLSFile(const char *user_dls)
{
        DMUS_PORTCAPS caps;
        MemSetT(&caps, 0);
        caps.dwSize = sizeof(DMUS_PORTCAPS);
        _port->GetCaps(&caps);

        /* Nothing to unless it is a synth with instrument download that doesn't come with GM voices by default. */
        if ((caps.dwFlags & (DMUS_PC_DLS | DMUS_PC_DLS2)) != 0 && (caps.dwFlags & DMUS_PC_GMINHARDWARE) == 0) {
                DLSFile dls_file;

                if (user_dls == nullptr) {
                        /* Try loading the default GM DLS file stored in the registry. */
                        HKEY hkDM;
                        if (SUCCEEDED(RegOpenKeyEx(HKEY_LOCAL_MACHINE, L"Software\\Microsoft\\DirectMusic", 0, KEY_READ, &hkDM))) {
                                wchar_t dls_path[MAX_PATH];
                                DWORD buf_size = sizeof(dls_path); // Buffer size as to be given in bytes!
                                if (SUCCEEDED(RegQueryValueEx(hkDM, L"GMFilePath", nullptr, nullptr, (LPBYTE)dls_path, &buf_size))) {
                                        wchar_t expand_path[MAX_PATH * 2];
                                        ExpandEnvironmentStrings(dls_path, expand_path, static_cast<DWORD>(std::size(expand_path)));
                                        if (!dls_file.LoadFile(FS2OTTD(expand_path))) Debug(driver, 1, "Failed to load default GM DLS file from registry");
                                }
                                RegCloseKey(hkDM);
                        }

                        /* If we couldn't load the file from the registry, try again at the default install path of the GM DLS file. */
                        if (dls_file.instruments.empty()) {
                                static const wchar_t *DLS_GM_FILE = L"%windir%\\System32\\drivers\\gm.dls";
                                wchar_t path[MAX_PATH];
                                ExpandEnvironmentStrings(DLS_GM_FILE, path, static_cast<DWORD>(std::size(path)));

                                if (!dls_file.LoadFile(FS2OTTD(path))) return "Can't load GM DLS collection";
                        }
                } else {
                        if (!dls_file.LoadFile(user_dls)) return "Can't load GM DLS collection";
                }

                /* Get download port and allocate download IDs. */
                IDirectMusicPortDownload *download_port = nullptr;
                if (FAILED(_port->QueryInterface(IID_IDirectMusicPortDownload, (LPVOID *)&download_port))) return "Can't get download port";

                DWORD dlid_wave = 0, dlid_inst = 0;
                if (FAILED(download_port->GetDLId(&dlid_wave, (DWORD)dls_file.waves.size())) || FAILED(download_port->GetDLId(&dlid_inst, (DWORD)dls_file.instruments.size()))) {
                        download_port->Release();
                        return "Can't get enough DLS ids";
                }

                DWORD dwAppend = 0;
                download_port->GetAppend(&dwAppend);

                /* Download wave data. */
                for (DWORD i = 0; i < dls_file.waves.size(); i++) {
                        IDirectMusicDownload *dl_wave = nullptr;
                        if (FAILED(download_port->AllocateBuffer((DWORD)(sizeof(WAVE_DOWNLOAD) + dwAppend * dls_file.waves[i].fmt.wf.nBlockAlign + dls_file.waves[i].data.size()), &dl_wave))) {
                                download_port->Release();
                                return "Can't allocate wave download buffer";
                        }

                        WAVE_DOWNLOAD *wave;
                        DWORD wave_size = 0;
                        if (FAILED(dl_wave->GetBuffer((LPVOID *)&wave, &wave_size))) {
                                dl_wave->Release();
                                download_port->Release();
                                return "Can't get wave download buffer";
                        }

                        /* Fill download data. */
                        MemSetT(wave, 0);
                        wave->dlInfo.dwDLType = DMUS_DOWNLOADINFO_WAVE;
                        wave->dlInfo.cbSize = wave_size;
                        wave->dlInfo.dwDLId = dlid_wave + i;
                        wave->dlInfo.dwNumOffsetTableEntries = 2;
                        wave->ulOffsetTable[0] = offsetof(WAVE_DOWNLOAD, dmWave);
                        wave->ulOffsetTable[1] = offsetof(WAVE_DOWNLOAD, dmWaveData);
                        wave->dmWave.ulWaveDataIdx = 1;
                        MemCpyT((PCMWAVEFORMAT *)&wave->dmWave.WaveformatEx, &dls_file.waves[i].fmt, 1);
                        wave->dmWaveData.cbSize = (DWORD)dls_file.waves[i].data.size();
                        MemCpyT(wave->dmWaveData.byData, &dls_file.waves[i].data[0], dls_file.waves[i].data.size());

                        _dls_downloads.push_back(dl_wave);
                        if (FAILED(download_port->Download(dl_wave))) {
                                download_port->Release();
                                return "Downloading DLS wave failed";
                        }
                }

                /* Download instrument data. */
                for (DWORD i = 0; i < dls_file.instruments.size(); i++) {
                        DWORD offsets = 1 + (DWORD)dls_file.instruments[i].regions.size();

                        /* Calculate download size for the instrument. */
                        size_t i_size = sizeof(DMUS_DOWNLOADINFO) + sizeof(DMUS_INSTRUMENT);
                        if (!dls_file.instruments[i].articulators.empty()) {
                                /* Articulations are stored as two chunks, one containing meta data and one with the actual articulation data. */
                                offsets += 2;
                                i_size += sizeof(DMUS_ARTICULATION2) + sizeof(CONNECTIONLIST) + sizeof(CONNECTION) * dls_file.instruments[i].articulators.size();
                        }

                        for (std::vector<DLSFile::DLSRegion>::iterator rgn = dls_file.instruments[i].regions.begin(); rgn != dls_file.instruments[i].regions.end(); rgn++) {
                                if (!rgn->articulators.empty()) {
                                        offsets += 2;
                                        i_size += sizeof(DMUS_ARTICULATION2) + sizeof(CONNECTIONLIST) + sizeof(CONNECTION) * rgn->articulators.size();
                                }

                                /* Region size depends on the number of wave loops. The size of the
                                 * declared structure already accounts for one loop. */
                                if (rgn->wave_sample.cbSize != 0) {
                                        i_size += sizeof(DMUS_REGION) - sizeof(DMUS_REGION::WLOOP) + sizeof(WLOOP) * rgn->wave_loops.size();
                                } else {
                                        i_size += sizeof(DMUS_REGION) - sizeof(DMUS_REGION::WLOOP) + sizeof(WLOOP) * dls_file.waves[dls_file.pool_cues[rgn->wave.ulTableIndex].ulOffset].wave_loops.size();
                                }
                        }

                        i_size += offsets * sizeof(ULONG);

                        /* Allocate download buffer. */
                        IDirectMusicDownload *dl_inst = nullptr;
                        if (FAILED(download_port->AllocateBuffer((DWORD)i_size, &dl_inst))) {
                                download_port->Release();
                                return "Can't allocate instrument download buffer";
                        }

                        void *instrument;
                        DWORD inst_size = 0;
                        if (FAILED(dl_inst->GetBuffer((LPVOID *)&instrument, &inst_size))) {
                                dl_inst->Release();
                                download_port->Release();
                                return "Can't get instrument download buffer";
                        }
                        char *inst_base = (char *)instrument;

                        /* Fill download header. */
                        DMUS_DOWNLOADINFO *d_info = (DMUS_DOWNLOADINFO *)instrument;
                        d_info->dwDLType = DMUS_DOWNLOADINFO_INSTRUMENT2;
                        d_info->cbSize = inst_size;
                        d_info->dwDLId = dlid_inst + i;
                        d_info->dwNumOffsetTableEntries = offsets;
                        instrument = d_info + 1;

                        /* Download offset table; contains the offsets of all chunks relative to the buffer start. */
                        ULONG *offset_table = (ULONG *)instrument;
                        instrument = offset_table + offsets;
                        int last_offset = 0;

                        /* Instrument header. */
                        DMUS_INSTRUMENT *inst_data = (DMUS_INSTRUMENT *)instrument;
                        MemSetT(inst_data, 0);
                        offset_table[last_offset++] = (char *)inst_data - inst_base;
                        inst_data->ulPatch = (dls_file.instruments[i].hdr.Locale.ulBank & F_INSTRUMENT_DRUMS) | ((dls_file.instruments[i].hdr.Locale.ulBank & 0x7F7F) << 8) | (dls_file.instruments[i].hdr.Locale.ulInstrument & 0x7F);
                        instrument = inst_data + 1;

                        /* Write global articulations. */
                        if (!dls_file.instruments[i].articulators.empty()) {
                                inst_data->ulGlobalArtIdx = last_offset;
                                offset_table[last_offset++] = (char *)instrument - inst_base;
                                offset_table[last_offset++] = (char *)instrument + sizeof(DMUS_ARTICULATION2) - inst_base;

                                instrument = DownloadArticulationData(inst_data->ulGlobalArtIdx, instrument, dls_file.instruments[i].articulators);
                                assert((char *)instrument - inst_base <= (ptrdiff_t)inst_size);
                        }

                        /* Write out regions. */
                        inst_data->ulFirstRegionIdx = last_offset;
                        for (uint j = 0; j < dls_file.instruments[i].regions.size(); j++) {
                                DLSFile::DLSRegion &rgn = dls_file.instruments[i].regions[j];

                                DMUS_REGION *inst_region = (DMUS_REGION *)instrument;
                                offset_table[last_offset++] = (char *)inst_region - inst_base;
                                inst_region->RangeKey = rgn.hdr.RangeKey;
                                inst_region->RangeVelocity = rgn.hdr.RangeVelocity;
                                inst_region->fusOptions = rgn.hdr.fusOptions;
                                inst_region->usKeyGroup = rgn.hdr.usKeyGroup;
                                inst_region->ulFirstExtCkIdx = 0;

                                ULONG wave_id = dls_file.pool_cues[rgn.wave.ulTableIndex].ulOffset;
                                inst_region->WaveLink = rgn.wave;
                                inst_region->WaveLink.ulTableIndex = wave_id + dlid_wave;

                                /* The wave sample data will be taken from the region, if defined, otherwise from the wave itself. */
                                if (rgn.wave_sample.cbSize != 0) {
                                        inst_region->WSMP = rgn.wave_sample;
                                        if (!rgn.wave_loops.empty()) MemCpyT(inst_region->WLOOP, &rgn.wave_loops.front(), rgn.wave_loops.size());

                                        instrument = (char *)(inst_region + 1) - sizeof(DMUS_REGION::WLOOP) + sizeof(WLOOP) * rgn.wave_loops.size();
                                } else {
                                        inst_region->WSMP = rgn.wave_sample;
                                        if (!dls_file.waves[wave_id].wave_loops.empty()) MemCpyT(inst_region->WLOOP, &dls_file.waves[wave_id].wave_loops.front(), dls_file.waves[wave_id].wave_loops.size());

                                        instrument = (char *)(inst_region + 1) - sizeof(DMUS_REGION::WLOOP) + sizeof(WLOOP) * dls_file.waves[wave_id].wave_loops.size();
                                }

                                /* Write local articulator data. */
                                if (!rgn.articulators.empty()) {
                                        inst_region->ulRegionArtIdx = last_offset;
                                        offset_table[last_offset++] = (char *)instrument - inst_base;
                                        offset_table[last_offset++] = (char *)instrument + sizeof(DMUS_ARTICULATION2) - inst_base;

                                        instrument = DownloadArticulationData(inst_region->ulRegionArtIdx, instrument, rgn.articulators);
                                } else {
                                        inst_region->ulRegionArtIdx = 0;
                                }
                                assert((char *)instrument - inst_base <= (ptrdiff_t)inst_size);

                                /* Link to the next region unless this was the last one.*/
                                inst_region->ulNextRegionIdx = j < dls_file.instruments[i].regions.size() - 1 ? last_offset : 0;
                        }

                        _dls_downloads.push_back(dl_inst);
                        if (FAILED(download_port->Download(dl_inst))) {
                                download_port->Release();
                                return "Downloading DLS instrument failed";
                        }
                }

                download_port->Release();
        }

        return nullptr;
}


std::optional<std::string_view> MusicDriver_DMusic::Start(const StringList &parm)
{
        /* Initialize COM */
        if (FAILED(CoInitializeEx(nullptr, COINIT_MULTITHREADED))) return "COM initialization failed";

        /* Create the DirectMusic object */
        if (FAILED(CoCreateInstance(
                                CLSID_DirectMusic,
                                nullptr,
                                CLSCTX_INPROC,
                                IID_IDirectMusic,
                                (LPVOID*)&_music
                        ))) {
                return "Failed to create the music object";
        }

        /* Assign sound output device. */
        if (FAILED(_music->SetDirectSound(nullptr, nullptr))) return "Can't set DirectSound interface";

        /* MIDI events need to be send to the synth in time before their playback time
         * has come. By default, we try send any events at least 50 ms before playback. */
        _playback.preload_time = GetDriverParamInt(parm, "preload", 50);

        int pIdx = GetDriverParamInt(parm, "port", -1);
        if (_debug_driver_level > 0) {
                /* Print all valid output ports. */
                char desc[DMUS_MAX_DESCRIPTION];

                DMUS_PORTCAPS caps;
                MemSetT(&caps, 0);
                caps.dwSize = sizeof(DMUS_PORTCAPS);

                Debug(driver, 1, "Detected DirectMusic ports:");
                for (int i = 0; _music->EnumPort(i, &caps) == S_OK; i++) {
                        if (caps.dwClass == DMUS_PC_OUTPUTCLASS) {
                                Debug(driver, 1, " {}: {}{}", i, convert_from_fs(caps.wszDescription, desc), i == pIdx ? " (selected)" : "");
                        }
                }
        }

        GUID guidPort;
        if (pIdx >= 0) {
                /* Check if the passed port is a valid port. */
                DMUS_PORTCAPS caps;
                MemSetT(&caps, 0);
                caps.dwSize = sizeof(DMUS_PORTCAPS);
                if (FAILED(_music->EnumPort(pIdx, &caps))) return "Supplied port parameter is not a valid port";
                if (caps.dwClass != DMUS_PC_OUTPUTCLASS) return "Supplied port parameter is not an output port";
                guidPort = caps.guidPort;
        } else {
                if (FAILED(_music->GetDefaultPort(&guidPort))) return "Can't query default music port";
        }

        /* Create new port. */
        DMUS_PORTPARAMS params;
        MemSetT(&params, 0);
        params.dwSize = sizeof(DMUS_PORTPARAMS);
        params.dwValidParams = DMUS_PORTPARAMS_CHANNELGROUPS;
        params.dwChannelGroups = 1;
        if (FAILED(_music->CreatePort(guidPort, &params, &_port, nullptr))) return "Failed to create port";
        /* Activate port. */
        if (FAILED(_port->Activate(TRUE))) return "Failed to activate port";

        /* Create playback buffer. */
        DMUS_BUFFERDESC desc;
        MemSetT(&desc, 0);
        desc.dwSize = sizeof(DMUS_BUFFERDESC);
        desc.guidBufferFormat = KSDATAFORMAT_SUBTYPE_DIRECTMUSIC;
        desc.cbBuffer = 1024;
        if (FAILED(_music->CreateMusicBuffer(&desc, &_buffer, nullptr))) return "Failed to create music buffer";

        /* On soft-synths (e.g. the default DirectMusic one), we might need to load a wavetable set to get music. */
        const char *dls = LoadDefaultDLSFile(GetDriverParam(parm, "dls"));
        if (dls != nullptr) return dls;

        /* Create playback thread and synchronization primitives. */
        _thread_event = CreateEvent(nullptr, FALSE, FALSE, nullptr);
        if (_thread_event == nullptr) return "Can't create thread shutdown event";

        if (!StartNewThread(&_dmusic_thread, "ottd:dmusic", &MidiThreadProc)) return "Can't create MIDI output thread";

        return std::nullopt;
}


MusicDriver_DMusic::~MusicDriver_DMusic()
{
        this->Stop();
}


void MusicDriver_DMusic::Stop()
{
        if (_dmusic_thread.joinable()) {
                _playback.shutdown = true;
                SetEvent(_thread_event);
                _dmusic_thread.join();
        }

        /* Unloaded any instruments we loaded. */
        if (!_dls_downloads.empty()) {
                IDirectMusicPortDownload *download_port = nullptr;
                _port->QueryInterface(IID_IDirectMusicPortDownload, (LPVOID *)&download_port);

                /* Instruments refer to waves. As the waves are at the beginning of the download list,
                 * do the unload from the back so that references are cleared properly. */
                for (std::vector<IDirectMusicDownload *>::reverse_iterator i = _dls_downloads.rbegin(); download_port != nullptr && i != _dls_downloads.rend(); i++) {
                        download_port->Unload(*i);
                        (*i)->Release();
                }
                _dls_downloads.clear();

                if (download_port != nullptr) download_port->Release();
        }

        if (_buffer != nullptr) {
                _buffer->Release();
                _buffer = nullptr;
        }

        if (_port != nullptr) {
                _port->Activate(FALSE);
                _port->Release();
                _port = nullptr;
        }

        if (_music != nullptr) {
                _music->Release();
                _music = nullptr;
        }

        CloseHandle(_thread_event);

        CoUninitialize();
}


void MusicDriver_DMusic::PlaySong(const MusicSongInfo &song)
{
        std::lock_guard<std::mutex> lock(_thread_mutex);

        if (!_playback.next_file.LoadSong(song)) return;

        _playback.next_segment.start = song.override_start;
        _playback.next_segment.end = song.override_end;
        _playback.next_segment.loop = song.loop;

        _playback.do_start = true;
        SetEvent(_thread_event);
}


void MusicDriver_DMusic::StopSong()
{
        _playback.do_stop = true;
        SetEvent(_thread_event);
}


bool MusicDriver_DMusic::IsSongPlaying()
{
        return _playback.playing || _playback.do_start;
}


void MusicDriver_DMusic::SetVolume(uint8_t vol)
{
        _playback.new_volume = vol;
}