SRB2/src/sdl/mixer_sound.c

// SONIC ROBO BLAST 2
//-----------------------------------------------------------------------------
// Copyright (C) 2014-2019 by Sonic Team Junior.
//
// This program is free software distributed under the
// terms of the GNU General Public License, version 2.
// See the 'LICENSE' file for more details.
//-----------------------------------------------------------------------------
/// \file
/// \brief SDL Mixer interface for sound

#ifdef HAVE_LIBGME
#ifdef HAVE_ZLIB
#ifndef _MSC_VER
#ifndef _LARGEFILE64_SOURCE
#define _LARGEFILE64_SOURCE
#endif
#endif

#ifndef _LFS64_LARGEFILE
#define _LFS64_LARGEFILE
#endif

#ifndef _FILE_OFFSET_BITS
#define _FILE_OFFSET_BITS 0
#endif

#include <zlib.h>
#endif // HAVE_ZLIB
#endif // HAVE_LIBGME

#include "../doomdef.h"
#include "../doomstat.h" // menuactive

#if defined(HAVE_SDL) && defined(HAVE_MIXER) && SOUND==SOUND_MIXER

#include "../sounds.h"
#include "../s_sound.h"
#include "../i_sound.h"
#include "../w_wad.h"
#include "../z_zone.h"
#include "../byteptr.h"

#ifdef _MSC_VER
#pragma warning(disable : 4214 4244)
#endif
#include "SDL.h"
#ifdef _MSC_VER
#pragma warning(default : 4214 4244)
#endif

#ifdef HAVE_MIXERX
#include "SDL_mixer_ext.h"
#else
#include "SDL_mixer.h"
#endif

/* This is the version number macro for the current SDL_mixer version: */
#ifndef SDL_MIXER_COMPILEDVERSION
#define SDL_MIXER_COMPILEDVERSION \
	SDL_VERSIONNUM(MIX_MAJOR_VERSION, MIX_MINOR_VERSION, MIX_PATCHLEVEL)
#endif

/* This macro will evaluate to true if compiled with SDL_mixer at least X.Y.Z */
#ifndef SDL_MIXER_VERSION_ATLEAST
#define SDL_MIXER_VERSION_ATLEAST(X, Y, Z) \
	(SDL_MIXER_COMPILEDVERSION >= SDL_VERSIONNUM(X, Y, Z))
#endif

// thanks alam for making the buildbots happy!
#if SDL_MIXER_VERSION_ATLEAST(2,0,2)
#define MUS_MP3_MAD MUS_MP3_MAD_UNUSED
#define MUS_MODPLUG MUS_MODPLUG_UNUSED
#endif

#ifdef HAVE_LIBGME
#include "gme/gme.h"
#define GME_TREBLE 5.0f
#define GME_BASS 1.0f
#endif // HAVE_LIBGME

static UINT16 BUFFERSIZE = 2048;
static UINT16 SAMPLERATE = 44100;

#ifdef HAVE_OPENMPT
#include "libopenmpt/libopenmpt.h"
#endif

/// ------------------------
/// Audio Declarations
/// ------------------------

UINT8 sound_started = false;

static Mix_Music *music;
static UINT8 music_volume, sfx_volume, internal_volume;
static float loop_point;
static float song_length; // length in seconds
static boolean songpaused;
static UINT32 music_bytes;
static boolean is_looping;

// fading
static boolean is_fading;
static UINT8 fading_source;
static UINT8 fading_target;
static UINT32 fading_timer;
static UINT32 fading_duration;
static INT32 fading_id;
static void (*fading_callback)(void);
static boolean fading_nocleanup;

#ifdef HAVE_LIBGME
static Music_Emu *gme;
static UINT16 current_track;
#endif

#ifdef HAVE_OPENMPT
static int mod_err = OPENMPT_ERROR_OK;
static const char *mod_err_str;
static UINT16 current_subsong;
static size_t probesize;
static int result;
#endif

#ifdef HAVE_MIXERX
static void Midiplayer_Onchange(void)
{
	boolean restart = false;

	if (I_SongType() != MU_NONE && I_SongType() != MU_MID_EX && I_SongType() != MU_MID)
		return;

	if (Mix_GetMidiPlayer() != cv_midiplayer.value)
	{
		if (Mix_SetMidiPlayer(cv_midiplayer.value)) // <> 0 means error
			CONS_Alert(CONS_ERROR, "Midi player error: %s", Mix_GetError());
		else
			restart = true;
	}

	if (stricmp(Mix_GetSoundFonts(), cv_midisoundfontpath.string))
	{
		if (!Mix_SetSoundFonts(cv_midisoundfontpath.string)) // == 0 means error
			CONS_Alert(CONS_ERROR, "Sound font error: %s", Mix_GetError());
		else
			restart = true;
	}

	Mix_Timidity_addToPathList(cv_miditimiditypath.string);

	if (restart)
		S_StartEx(true);
}

static void MidiSoundfontPath_Onchange(void)
{
	if (Mix_GetMidiPlayer() != MIDI_Fluidsynth || (I_SongType() != MU_NONE && I_SongType() != MU_MID_EX))
		return;

	if (stricmp(Mix_GetSoundFonts(), cv_midisoundfontpath.string))
	{
		char *miditoken;
		char *source = strdup(cv_midisoundfontpath.string);
		boolean proceed = true;
		// check if file exists; menu calls this method at every keystroke

		// get first token
		miditoken = strtok(source, ";");

		while (miditoken != NULL)
		{
			SDL_RWops *rw = SDL_RWFromFile(miditoken, "r");
			if (rw != NULL)
				SDL_RWclose(rw);
			else
			{
				proceed = false;
				break;
			}
			miditoken = strtok(NULL, ";");
		}

		free(source);

		if (proceed)
		{
			if (!Mix_SetSoundFonts(cv_midisoundfontpath.string))
				CONS_Alert(CONS_ERROR, "Sound font error: %s", Mix_GetError());
			else
				S_StartEx(true);
		}
	}
}

// make sure that s_sound.c does not already verify these
// which happens when: defined(HAVE_MIXERX) && !defined(HAVE_MIXER)
static CV_PossibleValue_t midiplayer_cons_t[] = {{MIDI_OPNMIDI, "OPNMIDI"}, {MIDI_Fluidsynth, "Fluidsynth"}, {MIDI_Timidity, "Timidity"}, {MIDI_Native, "Native"}, {0, NULL}};
consvar_t cv_midiplayer = {"midiplayer", "OPNMIDI" /*MIDI_OPNMIDI*/, CV_CALL|CV_NOINIT|CV_SAVE, midiplayer_cons_t, Midiplayer_Onchange, 0, NULL, NULL, 0, 0, NULL};
consvar_t cv_midisoundfontpath = {"midisoundfont", "sf2/8bitsf.SF2", CV_CALL|CV_NOINIT|CV_SAVE, NULL, MidiSoundfontPath_Onchange, 0, NULL, NULL, 0, 0, NULL};
consvar_t cv_miditimiditypath = {"midisoundbank", "./timidity", CV_SAVE, NULL, NULL, 0, NULL, NULL, 0, 0, NULL};
#endif

static void var_cleanup(void)
{
	song_length = loop_point = 0.0f;
	music_bytes = fading_source = fading_target =\
	 fading_timer = fading_duration = 0;

	songpaused = is_looping =\
	 is_fading = false;

	// HACK: See music_loop, where we want the fade timing to proceed after a non-looping
	// song has stopped playing
	if (!fading_nocleanup)
		fading_callback = NULL;
	else
		fading_nocleanup = false; // use it once, set it back immediately

	internal_volume = 100;
}
/// ------------------------
/// Audio System
/// ------------------------

void I_StartupSound(void)
{
	//I_Assert(!sound_started);
	if (sound_started)
		return;

#ifdef _WIN32
	// Force DirectSound instead of WASAPI
	// SDL 2.0.6+ defaults to the latter and it screws up our sound effects
	SDL_setenv("SDL_AUDIODRIVER", "directsound", 1);
#endif

	// EE inits audio first so we're following along.
	if (SDL_WasInit(SDL_INIT_AUDIO) == SDL_INIT_AUDIO)
	{
		CONS_Debug(DBG_DETAILED, "SDL Audio already started\n");
		return;
	}
	else if (SDL_InitSubSystem(SDL_INIT_AUDIO) < 0)
	{
		CONS_Alert(CONS_ERROR, "Error initializing SDL Audio: %s\n", SDL_GetError());
		// call to start audio failed -- we do not have it
		return;
	}

	fading_nocleanup = false;

	var_cleanup();

	music = NULL;
	music_volume = sfx_volume = 0;

#ifdef HAVE_MIXERX
	Mix_SetMidiPlayer(cv_midiplayer.value);
	Mix_SetSoundFonts(cv_midisoundfontpath.string);
	Mix_Timidity_addToPathList(cv_miditimiditypath.string);
#endif
#if SDL_MIXER_VERSION_ATLEAST(1,2,11)
	Mix_Init(MIX_INIT_FLAC|MIX_INIT_MP3|MIX_INIT_OGG|MIX_INIT_MOD);
#endif

	if (Mix_OpenAudio(SAMPLERATE, AUDIO_S16SYS, 2, BUFFERSIZE) < 0)
	{
		CONS_Alert(CONS_ERROR, "Error starting SDL_Mixer: %s\n", Mix_GetError());
		// call to start audio failed -- we do not have it
		return;
	}

#ifdef HAVE_OPENMPT
	CONS_Printf("libopenmpt version: %s\n", openmpt_get_string("library_version"));
	CONS_Printf("libopenmpt build date: %s\n", openmpt_get_string("build"));
#endif

	sound_started = true;
	songpaused = false;
	Mix_AllocateChannels(256);
}

void I_ShutdownSound(void)
{
	if (!sound_started)
		return; // not an error condition
	sound_started = false;

	Mix_CloseAudio();
#if SDL_MIXER_VERSION_ATLEAST(1,2,11)
	Mix_Quit();
#endif

	SDL_QuitSubSystem(SDL_INIT_AUDIO);

#ifdef HAVE_LIBGME
	if (gme)
		gme_delete(gme);
#endif
#ifdef HAVE_OPENMPT
	if (openmpt_mhandle)
		openmpt_module_destroy(openmpt_mhandle);
#endif
}

void I_UpdateSound(void)
{
}

/// ------------------------
/// SFX
/// ------------------------

// this is as fast as I can possibly make it.
// sorry. more asm needed.
static Mix_Chunk *ds2chunk(void *stream)
{
	UINT16 ver,freq;
	UINT32 samples, i, newsamples;
	UINT8 *sound;

	SINT8 *s;
	INT16 *d;
	INT16 o;
	fixed_t step, frac;

	// lump header
	ver = READUINT16(stream); // sound version format?
	if (ver != 3) // It should be 3 if it's a doomsound...
		return NULL; // onos! it's not a doomsound!
	freq = READUINT16(stream);
	samples = READUINT32(stream);

	// convert from signed 8bit ???hz to signed 16bit 44100hz.
	switch(freq)
	{
	case 44100:
		if (samples >= UINT32_MAX>>2)
			return NULL; // would wrap, can't store.
		newsamples = samples;
		break;
	case 22050:
		if (samples >= UINT32_MAX>>3)
			return NULL; // would wrap, can't store.
		newsamples = samples<<1;
		break;
	case 11025:
		if (samples >= UINT32_MAX>>4)
			return NULL; // would wrap, can't store.
		newsamples = samples<<2;
		break;
	default:
		frac = (44100 << FRACBITS) / (UINT32)freq;
		if (!(frac & 0xFFFF)) // other solid multiples (change if FRACBITS != 16)
			newsamples = samples * (frac >> FRACBITS);
		else // strange and unusual fractional frequency steps, plus anything higher than 44100hz.
			newsamples = FixedMul(FixedDiv(samples, freq), 44100) + 1; // add 1 to counter truncation.
		if (newsamples >= UINT32_MAX>>2)
			return NULL; // would and/or did wrap, can't store.
		break;
	}
	sound = Z_Malloc(newsamples<<2, PU_SOUND, NULL); // samples * frequency shift * bytes per sample * channels

	s = (SINT8 *)stream;
	d = (INT16 *)sound;

	i = 0;
	switch(freq)
	{
	case 44100: // already at the same rate? well that makes it simple.
		while(i++ < samples)
		{
			o = ((INT16)(*s++)+0x80)<<8; // changed signedness and shift up to 16 bits
			*d++ = o; // left channel
			*d++ = o; // right channel
		}
		break;
	case 22050: // unwrap 2x
		while(i++ < samples)
		{
			o = ((INT16)(*s++)+0x80)<<8; // changed signedness and shift up to 16 bits
			*d++ = o; // left channel
			*d++ = o; // right channel
			*d++ = o; // left channel
			*d++ = o; // right channel
		}
		break;
	case 11025: // unwrap 4x
		while(i++ < samples)
		{
			o = ((INT16)(*s++)+0x80)<<8; // changed signedness and shift up to 16 bits
			*d++ = o; // left channel
			*d++ = o; // right channel
			*d++ = o; // left channel
			*d++ = o; // right channel
			*d++ = o; // left channel
			*d++ = o; // right channel
			*d++ = o; // left channel
			*d++ = o; // right channel
		}
		break;
	default: // convert arbitrary hz to 44100.
		step = 0;
		frac = ((UINT32)freq << FRACBITS) / 44100 + 1; //Add 1 to counter truncation.
		while (i < samples)
		{
			o = (INT16)(*s+0x80)<<8; // changed signedness and shift up to 16 bits
			while (step < FRACUNIT) // this is as fast as I can make it.
			{
				*d++ = o; // left channel
				*d++ = o; // right channel
				step += frac;
			}
			do {
				i++; s++;
				step -= FRACUNIT;
			} while (step >= FRACUNIT);
		}
		break;
	}

	// return Mixer Chunk.
	return Mix_QuickLoad_RAW(sound, (Uint32)((UINT8*)d-sound));
}

void *I_GetSfx(sfxinfo_t *sfx)
{
	void *lump;
	Mix_Chunk *chunk;
	SDL_RWops *rw;
#ifdef HAVE_LIBGME
	Music_Emu *emu;
	gme_info_t *info;
#endif

	if (sfx->lumpnum == LUMPERROR)
		sfx->lumpnum = S_GetSfxLumpNum(sfx);
	sfx->length = W_LumpLength(sfx->lumpnum);

	lump = W_CacheLumpNum(sfx->lumpnum, PU_SOUND);

	// convert from standard DoomSound format.
	chunk = ds2chunk(lump);
	if (chunk)
	{
		Z_Free(lump);
		return chunk;
	}

	// Not a doom sound? Try something else.
#ifdef HAVE_LIBGME
	// VGZ format
	if (((UINT8 *)lump)[0] == 0x1F
		&& ((UINT8 *)lump)[1] == 0x8B)
	{
#ifdef HAVE_ZLIB
		UINT8 *inflatedData;
		size_t inflatedLen;
		z_stream stream;
		int zErr; // Somewhere to handle any error messages zlib tosses out

		memset(&stream, 0x00, sizeof (z_stream)); // Init zlib stream
		// Begin the inflation process
		inflatedLen = *(UINT32 *)lump + (sfx->length-4); // Last 4 bytes are the decompressed size, typically
		inflatedData = (UINT8 *)Z_Malloc(inflatedLen, PU_SOUND, NULL); // Make room for the decompressed data
		stream.total_in = stream.avail_in = sfx->length;
		stream.total_out = stream.avail_out = inflatedLen;
		stream.next_in = (UINT8 *)lump;
		stream.next_out = inflatedData;

		zErr = inflateInit2(&stream, 32 + MAX_WBITS);
		if (zErr == Z_OK) // We're good to go
		{
			zErr = inflate(&stream, Z_FINISH);
			if (zErr == Z_STREAM_END) {
				// Run GME on new data
				if (!gme_open_data(inflatedData, inflatedLen, &emu, 44100))
				{
					short *mem;
					UINT32 len;
					gme_equalizer_t eq = {GME_TREBLE, GME_BASS, 0,0,0,0,0,0,0,0};

					Z_Free(inflatedData); // GME supposedly makes a copy for itself, so we don't need this lying around
					Z_Free(lump); // We're done with the uninflated lump now, too.

					gme_start_track(emu, 0);
					gme_set_equalizer(emu, &eq);
					gme_track_info(emu, &info, 0);

					len = (info->play_length * 441 / 10) << 2;
					mem = Z_Malloc(len, PU_SOUND, 0);
					gme_play(emu, len >> 1, mem);
					gme_free_info(info);
					gme_delete(emu);

					return Mix_QuickLoad_RAW((Uint8 *)mem, len);
				}
			}
			else
			{
				const char *errorType;
				switch (zErr)
				{
					case Z_ERRNO:
						errorType = "Z_ERRNO"; break;
					case Z_STREAM_ERROR:
						errorType = "Z_STREAM_ERROR"; break;
					case Z_DATA_ERROR:
						errorType = "Z_DATA_ERROR"; break;
					case Z_MEM_ERROR:
						errorType = "Z_MEM_ERROR"; break;
					case Z_BUF_ERROR:
						errorType = "Z_BUF_ERROR"; break;
					case Z_VERSION_ERROR:
						errorType = "Z_VERSION_ERROR"; break;
					default:
						errorType = "unknown error";
				}
				CONS_Alert(CONS_ERROR,"Encountered %s when running inflate: %s\n", errorType, stream.msg);
			}
			(void)inflateEnd(&stream);
		}
		else // Hold up, zlib's got a problem
		{
			const char *errorType;
			switch (zErr)
			{
				case Z_ERRNO:
					errorType = "Z_ERRNO"; break;
				case Z_STREAM_ERROR:
					errorType = "Z_STREAM_ERROR"; break;
				case Z_DATA_ERROR:
					errorType = "Z_DATA_ERROR"; break;
				case Z_MEM_ERROR:
					errorType = "Z_MEM_ERROR"; break;
				case Z_BUF_ERROR:
					errorType = "Z_BUF_ERROR"; break;
				case Z_VERSION_ERROR:
					errorType = "Z_VERSION_ERROR"; break;
				default:
					errorType = "unknown error";
			}
			CONS_Alert(CONS_ERROR,"Encountered %s when running inflateInit: %s\n", errorType, stream.msg);
		}
		Z_Free(inflatedData); // GME didn't open jack, but don't let that stop us from freeing this up
#else
		return NULL; // No zlib support
#endif
	}
	// Try to read it as a GME sound
	else if (!gme_open_data(lump, sfx->length, &emu, 44100))
	{
		short *mem;
		UINT32 len;
		gme_equalizer_t eq = {GME_TREBLE, GME_BASS, 0,0,0,0,0,0,0,0};

		Z_Free(lump);

		gme_start_track(emu, 0);
		gme_set_equalizer(emu, &eq);
		gme_track_info(emu, &info, 0);

		len = (info->play_length * 441 / 10) << 2;
		mem = Z_Malloc(len, PU_SOUND, 0);
		gme_play(emu, len >> 1, mem);
		gme_free_info(info);
		gme_delete(emu);

		return Mix_QuickLoad_RAW((Uint8 *)mem, len);
	}
#endif

	// Try to load it as a WAVE or OGG using Mixer.
	rw = SDL_RWFromMem(lump, sfx->length);
	if (rw != NULL)
	{
		chunk = Mix_LoadWAV_RW(rw, 1);
		return chunk;
	}

	return NULL; // haven't been able to get anything
}

void I_FreeSfx(sfxinfo_t *sfx)
{
	if (sfx->data)
	{
		Mix_Chunk *chunk = (Mix_Chunk*)sfx->data;
		UINT8 *abufdata = NULL;
		if (chunk->allocated == 0)
		{
			// We allocated the data in this chunk, so get the abuf from mixer, then let it free the chunk, THEN we free the data
			// I believe this should ensure the sound is not playing when we free it
			abufdata = chunk->abuf;
		}
		Mix_FreeChunk(sfx->data);
		if (abufdata)
		{
			// I'm going to assume we used Z_Malloc to allocate this data.
			Z_Free(abufdata);
		}
	}
	sfx->data = NULL;
	sfx->lumpnum = LUMPERROR;
}

INT32 I_StartSound(sfxenum_t id, UINT8 vol, UINT8 sep, UINT8 pitch, UINT8 priority, INT32 channel)
{
	UINT8 volume = (((UINT16)vol + 1) * (UINT16)sfx_volume) / 62; // (256 * 31) / 62 == 127
	INT32 handle = Mix_PlayChannel(channel, S_sfx[id].data, 0);
	Mix_Volume(handle, volume);
	Mix_SetPanning(handle, min((UINT16)(0xff-sep)<<1, 0xff), min((UINT16)(sep)<<1, 0xff));
	(void)pitch; // Mixer can't handle pitch
	(void)priority; // priority and channel management is handled by SRB2...
	return handle;
}

void I_StopSound(INT32 handle)
{
	Mix_HaltChannel(handle);
}

boolean I_SoundIsPlaying(INT32 handle)
{
	return Mix_Playing(handle);
}

void I_UpdateSoundParams(INT32 handle, UINT8 vol, UINT8 sep, UINT8 pitch)
{
	UINT8 volume = (((UINT16)vol + 1) * (UINT16)sfx_volume) / 62; // (256 * 31) / 62 == 127
	Mix_Volume(handle, volume);
	Mix_SetPanning(handle, min((UINT16)(0xff-sep)<<1, 0xff), min((UINT16)(sep)<<1, 0xff));
	(void)pitch;
}

void I_SetSfxVolume(UINT8 volume)
{
	sfx_volume = volume;
}

/// ------------------------
/// Music Utilities
/// ------------------------

static UINT32 get_real_volume(UINT8 volume)
{
#ifdef _WIN32
	if (I_SongType() == MU_MID)
		// HACK: Until we stop using native MIDI,
		// disable volume changes
		return ((UINT32)31*128/31); // volume = 31
	else
#endif
		// convert volume to mixer's 128 scale
		// then apply internal_volume as a percentage
		return ((UINT32)volume*128/31) * (UINT32)internal_volume / 100;
}

static UINT32 get_adjusted_position(UINT32 position)
{
	// all in milliseconds
	UINT32 length = I_GetSongLength();
	UINT32 looppoint = I_GetSongLoopPoint();
	if (length)
		return position >= length ? (position % (length-looppoint)) : position;
	else
		return position;
}

static void do_fading_callback(void)
{
	if (fading_callback)
		(*fading_callback)();
	fading_callback = NULL;
}

/// ------------------------
/// Music Hooks
/// ------------------------

static void count_music_bytes(int chan, void *stream, int len, void *udata)
{
	(void)chan;
	(void)stream;
	(void)udata;

	if (!music || I_SongType() == MU_GME || I_SongType() == MU_MOD || I_SongType() == MU_MID)
		return;
	music_bytes += len;
}

static void music_loop(void)
{
	if (is_looping)
	{
		Mix_PlayMusic(music, 0);
		Mix_SetMusicPosition(loop_point);
		music_bytes = (UINT32)(loop_point*44100.0L*4); //assume 44.1khz, 4-byte length (see I_GetSongPosition)
	}
	else
	{
		// HACK: Let fade timing proceed beyond the end of a
		// non-looping song. This is a specific case where the timing
		// should persist after stopping a song, so I don't believe
		// this should apply every time the user stops a song.
		// This is auto-unset in var_cleanup, called by I_StopSong
		fading_nocleanup = true;
		I_StopSong();
	}
}

static UINT32 music_fade(UINT32 interval, void *param)
{
	(void)param;

	if (!is_fading ||
		internal_volume == fading_target ||
		fading_duration == 0)
	{
		I_StopFadingSong();
		do_fading_callback();
		return 0;
	}
	else if (songpaused) // don't decrement timer
		return interval;
	else if ((fading_timer -= 10) <= 0)
	{
		internal_volume = fading_target;
		Mix_VolumeMusic(get_real_volume(music_volume));
		I_StopFadingSong();
		do_fading_callback();
		return 0;
	}
	else
	{
		UINT8 delta = abs(fading_target - fading_source);
		fixed_t factor = FixedDiv(fading_duration - fading_timer, fading_duration);
		if (fading_target < fading_source)
			internal_volume = max(min(internal_volume, fading_source - FixedMul(delta, factor)), fading_target);
		else if (fading_target > fading_source)
			internal_volume = min(max(internal_volume, fading_source + FixedMul(delta, factor)), fading_target);
		Mix_VolumeMusic(get_real_volume(music_volume));
		return interval;
	}
}

#ifdef HAVE_LIBGME
static void mix_gme(void *udata, Uint8 *stream, int len)
{
	int i;
	short *p;

	(void)udata;

	// no gme? no music.
	if (!gme || gme_track_ended(gme) || songpaused)
		return;

	// play gme into stream
	gme_play(gme, len/2, (short *)stream);

	// Limiter to prevent music from being disorted with some formats
	if (music_volume >= 18)
		music_volume = 18;

	// apply volume to stream
	for (i = 0, p = (short *)stream; i < len/2; i++, p++)
		*p = ((INT32)*p) * (music_volume*internal_volume/100)*2 / 40;
}
#endif

#ifdef HAVE_OPENMPT
static void mix_openmpt(void *udata, Uint8 *stream, int len)
{
	int i;
	short *p;

	(void)udata;

	if (!openmpt_mhandle || songpaused)
		return;

	// Play module into stream
	openmpt_module_read_interleaved_stereo(openmpt_mhandle, SAMPLERATE, BUFFERSIZE, (short *)stream);

	// Limiter to prevent music from being disorted with some formats
	if (music_volume >= 18)
		music_volume = 18;

	// apply volume to stream
	for (i = 0, p = (short *)stream; i < len/2; i++, p++)
		*p = ((INT32)*p) * (music_volume*internal_volume/100)*2 / 40;
}
#endif

/// ------------------------
/// Music System
/// ------------------------

void I_InitMusic(void)
{
}

void I_ShutdownMusic(void)
{
	I_UnloadSong();
}

/// ------------------------
/// Music Properties
/// ------------------------

musictype_t I_SongType(void)
{
#ifdef HAVE_LIBGME
	if (gme)
		return MU_GME;
	else
#endif
#ifdef HAVE_OPENMPT
	if (openmpt_mhandle)
		return MU_MOD_EX;
#endif
	if (!music)
		return MU_NONE;
	else if (Mix_GetMusicType(music) == MUS_MID)
	{
#ifdef HAVE_MIXERX
		if (Mix_GetMidiPlayer() != MIDI_Native)
			return MU_MID_EX;
		else
#endif
		return MU_MID;
	}
	else if (Mix_GetMusicType(music) == MUS_MOD || Mix_GetMusicType(music) == MUS_MODPLUG)
		return MU_MOD;
	else if (Mix_GetMusicType(music) == MUS_MP3 || Mix_GetMusicType(music) == MUS_MP3_MAD)
		return MU_MP3;
	else
		return (musictype_t)Mix_GetMusicType(music);
}

boolean I_SongPlaying(void)
{
	return (
#ifdef HAVE_LIBGME
		(I_SongType() == MU_GME && gme) ||
#endif
#ifdef HAVE_OPENMPT
		(I_SongType() == MU_MOD_EX && openmpt_mhandle) ||
#endif
		music != NULL
	);
}

boolean I_SongPaused(void)
{
	return songpaused;
}

/// ------------------------
/// Music Effects
/// ------------------------

boolean I_SetSongSpeed(float speed)
{
	if (speed > 250.0f)
		speed = 250.0f; //limit speed up to 250x
#ifdef HAVE_LIBGME
	if (gme)
	{
		SDL_LockAudio();
		gme_set_tempo(gme, speed);
		SDL_UnlockAudio();
		return true;
	}
	else
#endif
#ifdef HAVE_OPENMPT
	if (openmpt_mhandle)
	{
		char modspd[13];

		if (speed > 4.0f)
			speed = 4.0f; // Limit this to 4x to prevent crashing, stupid fix but... ~SteelT 27/9/19

		sprintf(modspd, "%g", speed);
		openmpt_module_ctl_set(openmpt_mhandle, "play.tempo_factor", modspd);
		return true;
	}
#else
	(void)speed;
	return false;
#endif
	return false;
}

/// ------------------------
///  MUSIC SEEKING
/// ------------------------

UINT32 I_GetSongLength(void)
{
	INT32 length;

#ifdef HAVE_LIBGME
	if (gme)
	{
		gme_info_t *info;
		gme_err_t gme_e = gme_track_info(gme, &info, current_track);

		if (gme_e != NULL)
		{
			CONS_Alert(CONS_ERROR, "GME error: %s\n", gme_e);
			length = 0;
		}
		else
		{
			// reconstruct info->play_length, from GME source
			// we only want intro + 1 loop, not 2
			length = info->length;
			if (length <= 0)
			{
				length = info->intro_length + info->loop_length; // intro + 1 loop
				if (length <= 0)
					length = 150 * 1000; // 2.5 minutes
			}
		}

		gme_free_info(info);
		return max(length, 0);
	}
	else
#endif
#ifdef HAVE_OPENMPT
	if (openmpt_mhandle)
		return (UINT32)(openmpt_module_get_duration_seconds(openmpt_mhandle) * 1000.);
	else
#endif
	if (!music || I_SongType() == MU_MOD || I_SongType() == MU_MID)
		return 0;
	else
	{
#ifdef HAVE_MIXERX
		double xlength = Mix_GetMusicTotalTime(music);
		if (xlength >= 0)
			return (UINT32)(xlength*1000);
#endif
		// VERY IMPORTANT to set your LENGTHMS= in your song files, folks!
		// SDL mixer can't read music length itself.
		length = (UINT32)(song_length*1000);
		if (!length)
			CONS_Debug(DBG_DETAILED, "Getting music length: music is missing LENGTHMS= tag. Needed for seeking.\n");
		return length;
	}
}

boolean I_SetSongLoopPoint(UINT32 looppoint)
{
	if (!music || I_SongType() == MU_GME || I_SongType() == MU_MOD || I_SongType() == MU_MID || !is_looping)
		return false;
	else
	{
		UINT32 length = I_GetSongLength();

		if (length > 0)
			looppoint %= length;

		loop_point = max((float)(looppoint / 1000.0L), 0);
		return true;
	}
}

UINT32 I_GetSongLoopPoint(void)
{
#ifdef HAVE_LIBGME
	if (gme)
	{
		INT32 looppoint;
		gme_info_t *info;
		gme_err_t gme_e = gme_track_info(gme, &info, current_track);

		if (gme_e != NULL)
		{
			CONS_Alert(CONS_ERROR, "GME error: %s\n", gme_e);
			looppoint = 0;
		}
		else
			looppoint = info->intro_length > 0 ? info->intro_length : 0;

		gme_free_info(info);
		return max(looppoint, 0);
	}
	else
#endif
	if (!music || I_SongType() == MU_MOD || I_SongType() == MU_MID)
		return 0;
	else
		return (UINT32)(loop_point * 1000);
}

boolean I_SetSongPosition(UINT32 position)
{
	UINT32 length;
#ifdef HAVE_LIBGME
	if (gme)
	{
		// this is unstable, so fail silently
		return true;
		// this isn't required technically, but GME thread-locks for a second
		// if you seek too high from the counter
		// length = I_GetSongLength();
		// if (length)
		// 	position = get_adjusted_position(position);

		// SDL_LockAudio();
		// gme_err_t gme_e = gme_seek(gme, position);
		// SDL_UnlockAudio();

		// if (gme_e != NULL)
		// {
		// 	CONS_Alert(CONS_ERROR, "GME error: %s\n", gme_e);
		// 	return false;
		// }
		// else
		// 	return true;
	}
	else
#endif
#ifdef HAVE_OPENMPT
	if (openmpt_mhandle)
	{
		// This isn't 100% correct because we don't account for loop points because we can't get them.
		// But if you seek past end of song, OpenMPT seeks to 0. So adjust the position anyway.
		openmpt_module_set_position_seconds(openmpt_mhandle, (double)(get_adjusted_position(position)/1000.0L)); // returns new position
		return true;
	}
	else
#endif
	if (!music || I_SongType() == MU_MID)
		return false;
	else if (I_SongType() == MU_MOD)
		return Mix_SetMusicPosition(position); // Goes by channels
	else
	{
		// Because SDL mixer can't identify song length, if you have
		// a position input greater than the real length, then
		// music_bytes becomes inaccurate.

		length = I_GetSongLength(); // get it in MS
		if (length)
			position = get_adjusted_position(position);

		Mix_RewindMusic(); // needed for mp3
		if(Mix_SetMusicPosition((float)(position/1000.0L)) == 0)
			music_bytes = (UINT32)(position/1000.0L*44100.0L*4); //assume 44.1khz, 4-byte length (see I_GetSongPosition)
		else
			// NOTE: This block fires on incorrect song format,
			// NOT if position input is greater than song length.
			music_bytes = 0;

		return true;
	}
}

UINT32 I_GetSongPosition(void)
{
#ifdef HAVE_LIBGME
	if (gme)
	{
		INT32 position = gme_tell(gme);

		gme_info_t *info;
		gme_err_t gme_e = gme_track_info(gme, &info, current_track);

		if (gme_e != NULL)
		{
			CONS_Alert(CONS_ERROR, "GME error: %s\n", gme_e);
			return position;
		}
		else
		{
			// adjust position, since GME's counter keeps going past loop
			if (info->length > 0)
				position %= info->length;
			else if (info->intro_length + info->loop_length > 0)
				position = position >= (info->intro_length + info->loop_length) ? (position % info->loop_length) : position;
			else
				position %= 150 * 1000; // 2.5 minutes
		}

		gme_free_info(info);
		return max(position, 0);
	}
	else
#endif
#ifdef HAVE_OPENMPT
	if (openmpt_mhandle)
		// This will be incorrect if we adjust for length because we can't get loop points.
		// So return unadjusted. See note in SetMusicPosition: we adjust for that.
		return (UINT32)(openmpt_module_get_position_seconds(openmpt_mhandle)*1000.);
		//return get_adjusted_position((UINT32)(openmpt_module_get_position_seconds(openmpt_mhandle)*1000.));
	else
#endif
	if (!music || I_SongType() == MU_MID)
		return 0;
	else
	{
#ifdef HAVE_MIXERX
		double xposition = Mix_GetMusicPosition(music);
		if (xposition >= 0)
			return (UINT32)(xposition*1000);
#endif
		return (UINT32)(music_bytes/44100.0L*1000.0L/4); //assume 44.1khz
		// 4 = byte length for 16-bit samples (AUDIO_S16SYS), stereo (2-channel)
		// This is hardcoded in I_StartupSound. Other formats for factor:
		// 8M: 1 | 8S: 2 | 16M: 2 | 16S: 4
	}
}

/// ------------------------
/// Music Playback
/// ------------------------

boolean I_LoadSong(char *data, size_t len)
{
	const char *key1 = "LOOP";
	const char *key2 = "POINT=";
	const char *key3 = "MS=";
	const size_t key1len = strlen(key1);
	const size_t key2len = strlen(key2);
	const size_t key3len = strlen(key3);
	char *p = data;
	SDL_RWops *rw;

	if (music
#ifdef HAVE_LIBGME
		|| gme
#endif
#ifdef HAVE_OPENMPT
		|| openmpt_mhandle
#endif
	)
		I_UnloadSong();

	// always do this whether or not a music already exists
	var_cleanup();

#ifdef HAVE_LIBGME
	if ((UINT8)data[0] == 0x1F
		&& (UINT8)data[1] == 0x8B)
	{
#ifdef HAVE_ZLIB
		UINT8 *inflatedData;
		size_t inflatedLen;
		z_stream stream;
		int zErr; // Somewhere to handle any error messages zlib tosses out

		memset(&stream, 0x00, sizeof (z_stream)); // Init zlib stream
		// Begin the inflation process
		inflatedLen = *(UINT32 *)(data + (len-4)); // Last 4 bytes are the decompressed size, typically
		inflatedData = (UINT8 *)Z_Calloc(inflatedLen, PU_MUSIC, NULL); // Make room for the decompressed data
		stream.total_in = stream.avail_in = len;
		stream.total_out = stream.avail_out = inflatedLen;
		stream.next_in = (UINT8 *)data;
		stream.next_out = inflatedData;

		zErr = inflateInit2(&stream, 32 + MAX_WBITS);
		if (zErr == Z_OK) // We're good to go
		{
			zErr = inflate(&stream, Z_FINISH);
			if (zErr == Z_STREAM_END) {
				// Run GME on new data
				if (!gme_open_data(inflatedData, inflatedLen, &gme, 44100))
				{
					gme_equalizer_t eq = {GME_TREBLE, GME_BASS, 0,0,0,0,0,0,0,0};
					gme_start_track(gme, 0);
					current_track = 0;
					gme_set_equalizer(gme, &eq);
					Mix_HookMusic(mix_gme, gme);
					Z_Free(inflatedData); // GME supposedly makes a copy for itself, so we don't need this lying around
					return true;
				}
			}
			else
			{
				const char *errorType;
				switch (zErr)
				{
					case Z_ERRNO:
						errorType = "Z_ERRNO"; break;
					case Z_STREAM_ERROR:
						errorType = "Z_STREAM_ERROR"; break;
					case Z_DATA_ERROR:
						errorType = "Z_DATA_ERROR"; break;
					case Z_MEM_ERROR:
						errorType = "Z_MEM_ERROR"; break;
					case Z_BUF_ERROR:
						errorType = "Z_BUF_ERROR"; break;
					case Z_VERSION_ERROR:
						errorType = "Z_VERSION_ERROR"; break;
					default:
						errorType = "unknown error";
				}
				CONS_Alert(CONS_ERROR,"Encountered %s when running inflate: %s\n", errorType, stream.msg);
			}
			(void)inflateEnd(&stream);
		}
		else // Hold up, zlib's got a problem
		{
			const char *errorType;
			switch (zErr)
			{
				case Z_ERRNO:
					errorType = "Z_ERRNO"; break;
				case Z_STREAM_ERROR:
					errorType = "Z_STREAM_ERROR"; break;
				case Z_DATA_ERROR:
					errorType = "Z_DATA_ERROR"; break;
				case Z_MEM_ERROR:
					errorType = "Z_MEM_ERROR"; break;
				case Z_BUF_ERROR:
					errorType = "Z_BUF_ERROR"; break;
				case Z_VERSION_ERROR:
					errorType = "Z_VERSION_ERROR"; break;
				default:
					errorType = "unknown error";
			}
			CONS_Alert(CONS_ERROR,"Encountered %s when running inflateInit: %s\n", errorType, stream.msg);
		}
		Z_Free(inflatedData); // GME didn't open jack, but don't let that stop us from freeing this up
#else
		CONS_Alert(CONS_ERROR,"Cannot decompress VGZ; no zlib support\n");
		return true;
#endif
	}
	else if (!gme_open_data(data, len, &gme, 44100))
	{
		gme_equalizer_t eq = {GME_TREBLE, GME_BASS, 0,0,0,0,0,0,0,0};
		gme_set_equalizer(gme, &eq);
		return true;
	}
#endif

#ifdef HAVE_MIXERX
	if (Mix_GetMidiPlayer() != cv_midiplayer.value)
		Mix_SetMidiPlayer(cv_midiplayer.value);
	if (stricmp(Mix_GetSoundFonts(), cv_midisoundfontpath.string))
		Mix_SetSoundFonts(cv_midisoundfontpath.string);
	Mix_Timidity_addToPathList(cv_miditimiditypath.string); // this overwrites previous custom path
#endif

#ifdef HAVE_OPENMPT
	/*
		If the size of the data to be checked is bigger than the recommended size (> 2048 bytes)
		Let's just set the probe size to the recommended size
		Otherwise let's give it the full data size
	*/

	if (len > openmpt_probe_file_header_get_recommended_size())
		probesize = openmpt_probe_file_header_get_recommended_size();
	else
		probesize = len;

	result = openmpt_probe_file_header(OPENMPT_PROBE_FILE_HEADER_FLAGS_DEFAULT, data, probesize, len, NULL, NULL, NULL, NULL, NULL, NULL);

	if (result == OPENMPT_PROBE_FILE_HEADER_RESULT_SUCCESS) // We only cared if it succeeded, continue on if not.
	{
		openmpt_mhandle = openmpt_module_create_from_memory2(data, len, NULL, NULL, NULL, NULL, NULL, NULL, NULL);
		if (!openmpt_mhandle) // Failed to create module handle? Show error and return!
		{
			mod_err = openmpt_module_error_get_last(openmpt_mhandle);
			mod_err_str = openmpt_error_string(mod_err);
			CONS_Alert(CONS_ERROR, "openmpt_module_create_from_memory2: %s\n", mod_err_str);
			return false;
		}
		else
			return true; // All good and we're ready for music playback!
	}
#endif

	// Let's see if Mixer is able to load this.
	rw = SDL_RWFromMem(data, len);
	{
		music = Mix_LoadMUS_RW(rw, 1);
	}
	if (!music)
	{
		CONS_Alert(CONS_ERROR, "Mix_LoadMUS_RW: %s\n", Mix_GetError());
		return false;
	}

	// Find the OGG loop point.
	loop_point = 0.0f;
	song_length = 0.0f;

	while ((UINT32)(p - data) < len)
	{
		if (fpclassify(loop_point) == FP_ZERO && !strncmp(p, key1, key1len))
		{
			p += key1len; // skip LOOP
			if (!strncmp(p, key2, key2len)) // is it LOOPPOINT=?
			{
				p += key2len; // skip POINT=
				loop_point = (float)((44.1L+atoi(p)) / 44100.0L); // LOOPPOINT works by sample count.
				// because SDL_Mixer is USELESS and can't even tell us
				// something simple like the frequency of the streaming music,
				// we are unfortunately forced to assume that ALL MUSIC is 44100hz.
				// This means a lot of tracks that are only 22050hz for a reasonable downloadable file size will loop VERY badly.
			}
			else if (!strncmp(p, key3, key3len)) // is it LOOPMS=?
			{
				p += key3len; // skip MS=
				loop_point = (float)(atoi(p) / 1000.0L); // LOOPMS works by real time, as miliseconds.
				// Everything that uses LOOPMS will work perfectly with SDL_Mixer.
			}
		}

		if (fpclassify(loop_point) != FP_ZERO) // Got what we needed
			break;
		else // continue searching
			p++;
	}
	return true;
}

void I_UnloadSong(void)
{
	I_StopSong();

#ifdef HAVE_LIBGME
	if (gme)
	{
		gme_delete(gme);
		gme = NULL;
	}
#endif
#ifdef HAVE_OPENMPT
	if (openmpt_mhandle)
	{
		openmpt_module_destroy(openmpt_mhandle);
		openmpt_mhandle = NULL;
	}
#endif
	if (music)
	{
		Mix_FreeMusic(music);
		music = NULL;
	}
}

boolean I_PlaySong(boolean looping)
{
#ifdef HAVE_LIBGME
	if (gme)
	{
		gme_start_track(gme, 0);
		current_track = 0;
		Mix_HookMusic(mix_gme, gme);
		return true;
	}
	else
#endif
#ifdef HAVE_OPENMPT
	if (openmpt_mhandle)
	{
		openmpt_module_select_subsong(openmpt_mhandle, 0);
		openmpt_module_set_render_param(openmpt_mhandle, OPENMPT_MODULE_RENDER_INTERPOLATIONFILTER_LENGTH, cv_modfilter.value);
		if (looping)
			openmpt_module_set_repeat_count(openmpt_mhandle, -1); // Always repeat
		current_subsong = 0;
		Mix_HookMusic(mix_openmpt, openmpt_mhandle);
		return true;
	}
	else
#endif
	if (!music)
		return false;

	if (fpclassify(song_length) == FP_ZERO && (I_SongType() == MU_OGG || I_SongType() == MU_MP3 || I_SongType() == MU_FLAC))
		CONS_Debug(DBG_DETAILED, "This song is missing a LENGTHMS= tag! Required to make seeking work properly.\n");

	if (I_SongType() != MU_MOD && I_SongType() != MU_MID && Mix_PlayMusic(music, 0) == -1)
	{
		CONS_Alert(CONS_ERROR, "Mix_PlayMusic: %s\n", Mix_GetError());
		return false;
	}
	else if ((I_SongType() == MU_MOD || I_SongType() == MU_MID || I_SongType() == MU_MID_EX) && Mix_PlayMusic(music, looping ? -1 : 0) == -1) // if MOD, loop forever
	{
		CONS_Alert(CONS_ERROR, "Mix_PlayMusic: %s\n", Mix_GetError());
		return false;
	}

	is_looping = looping;

	I_SetMusicVolume(music_volume);

	if (I_SongType() != MU_MOD && I_SongType() != MU_MID && I_SongType() != MU_MID_EX)
		Mix_HookMusicFinished(music_loop); // don't bother counting if MOD

	if(I_SongType() != MU_MOD && I_SongType() != MU_MID && I_SongType() != MU_MID_EX && !Mix_RegisterEffect(MIX_CHANNEL_POST, count_music_bytes, NULL, NULL))
		CONS_Alert(CONS_WARNING, "Error registering SDL music position counter: %s\n", Mix_GetError());

	return true;
}

void I_StopSong(void)
{
	// HACK: See music_loop on why we want fade timing to proceed
	// after end of song
	if (!fading_nocleanup)
		I_StopFadingSong();

#ifdef HAVE_LIBGME
	if (gme)
	{
		Mix_HookMusic(NULL, NULL);
		current_track = -1;
	}
#endif
#ifdef HAVE_OPENMPT
	if (openmpt_mhandle)
	{
		Mix_HookMusic(NULL, NULL);
		current_subsong = -1;
	}
#endif
	if (music)
	{
		Mix_UnregisterEffect(MIX_CHANNEL_POST, count_music_bytes);
		Mix_HookMusicFinished(NULL);
		Mix_HaltMusic();
	}

	var_cleanup();
}

void I_PauseSong(void)
{
	if(I_SongType() == MU_MID) // really, SDL Mixer? why can't you pause MIDI???
		return;

	if(I_SongType() != MU_GME && I_SongType() != MU_MOD && I_SongType() != MU_MID)
		Mix_UnregisterEffect(MIX_CHANNEL_POST, count_music_bytes);

	Mix_PauseMusic();
	songpaused = true;
}

void I_ResumeSong(void)
{
	if (I_SongType() == MU_MID)
		return;

	if (I_SongType() != MU_GME && I_SongType() != MU_MOD && I_SongType() != MU_MID)
	{
		while(Mix_UnregisterEffect(MIX_CHANNEL_POST, count_music_bytes) != 0) { }
			// HACK: fixes issue of multiple effect callbacks being registered

		if(music && I_SongType() != MU_MOD && I_SongType() != MU_MID && !Mix_RegisterEffect(MIX_CHANNEL_POST, count_music_bytes, NULL, NULL))
			CONS_Alert(CONS_WARNING, "Error registering SDL music position counter: %s\n", Mix_GetError());
	}

	Mix_ResumeMusic();
	songpaused = false;
}

void I_SetMusicVolume(UINT8 volume)
{
	if (!I_SongPlaying())
		return;

#ifdef _WIN32
	if (I_SongType() == MU_MID)
		// HACK: Until we stop using native MIDI,
		// disable volume changes
		music_volume = 31;
	else
#endif
		music_volume = volume;

	Mix_VolumeMusic(get_real_volume(music_volume));
}

boolean I_SetSongTrack(int track)
{
#ifdef HAVE_LIBGME
	// If the specified track is within the number of tracks playing, then change it
	if (gme)
	{
		if (current_track == track)
			return false;
		SDL_LockAudio();
		if (track >= 0 && track < gme_track_count(gme)-1)
		{
			gme_err_t gme_e = gme_start_track(gme, track);
			if (gme_e != NULL)
			{
				CONS_Alert(CONS_ERROR, "GME error: %s\n", gme_e);
				return false;
			}
			current_track = track;
			SDL_UnlockAudio();
			return true;
		}
		SDL_UnlockAudio();
		return false;
	}
	else
#endif
#ifdef HAVE_OPENMPT
	if (openmpt_mhandle)
	{
		if (current_subsong == track)
			return false;
		SDL_LockAudio();
		if (track >= 0 && track < openmpt_module_get_num_subsongs(openmpt_mhandle))
		{
			openmpt_module_select_subsong(openmpt_mhandle, track);
			current_subsong = track;
			SDL_UnlockAudio();
			return true;
		}
		SDL_UnlockAudio();

		return false;
	}
#endif
	if (I_SongType() == MU_MOD)
		return !Mix_SetMusicPosition(track);
	(void)track;
	return false;
}

/// ------------------------
/// MUSIC FADING
/// ------------------------

void I_SetInternalMusicVolume(UINT8 volume)
{
	internal_volume = volume;
	if (!I_SongPlaying())
		return;
	Mix_VolumeMusic(get_real_volume(music_volume));
}

void I_StopFadingSong(void)
{
	if (fading_id)
		SDL_RemoveTimer(fading_id);
	is_fading = false;
	fading_source = fading_target = fading_timer = fading_duration = fading_id = 0;
	// don't unset fading_nocleanup here just yet; fading_callback is cleaned up
	// in var_cleanup()
}

boolean I_FadeSongFromVolume(UINT8 target_volume, UINT8 source_volume, UINT32 ms, void (*callback)(void))
{
	INT16 volume_delta;

	source_volume = min(source_volume, 100);
	volume_delta = (INT16)(target_volume - source_volume);

	I_StopFadingSong();

	if (!ms && volume_delta)
	{
		I_SetInternalMusicVolume(target_volume);
		if (callback)
			(*callback)();
		return true;

	}
	else if (!volume_delta)
	{
		if (callback)
			(*callback)();
		return true;
	}

	// Round MS to nearest 10
	// If n - lower > higher - n, then round up
	ms = (ms - ((ms / 10) * 10) > (((ms / 10) * 10) + 10) - ms) ?
		(((ms / 10) * 10) + 10) // higher
		: ((ms / 10) * 10); // lower

	if (!ms)
		I_SetInternalMusicVolume(target_volume);
	else if (source_volume != target_volume)
	{
		fading_id = SDL_AddTimer(10, music_fade, NULL);
		if (fading_id)
		{
			is_fading = true;
			fading_timer = fading_duration = ms;
			fading_source = source_volume;
			fading_target = target_volume;
			fading_callback = callback;

			if (internal_volume != source_volume)
				I_SetInternalMusicVolume(source_volume);
		}
	}

	return is_fading;
}

boolean I_FadeSong(UINT8 target_volume, UINT32 ms, void (*callback)(void))
{
	return I_FadeSongFromVolume(target_volume, internal_volume, ms, callback);
}

boolean I_FadeOutStopSong(UINT32 ms)
{
	return I_FadeSongFromVolume(0, internal_volume, ms, &I_StopSong);
}

boolean I_FadeInPlaySong(UINT32 ms, boolean looping)
{
	if (I_PlaySong(looping))
		return I_FadeSongFromVolume(100, 0, ms, NULL);
	else
		return false;
}
#endif