mixer.cpp File Reference

Mixing of sound samples. More...

#include "stdafx.h"
#include <mutex>
#include <atomic>
#include "core/math_func.hpp"
#include "framerate_type.h"
#include "mixer.h"
#include "settings_type.h"
#include "safeguards.h"

Go to the source code of this file.

Data Structures
struct	MixerChannel

Typedefs
using	MixerChannelMask = uint8_t
	Type representing a bitmask of mixer channels.

Functions
template<typename T >
static int	RateConversion (T *b, int frac_pos)
	Perform the rate conversion between the input and output.
template<typename T >
static void	mix_int16 (MixerChannel *sc, int16_t *buffer, uint samples, uint8_t effect_vol)
static void	MxCloseChannel (uint8_t channel_index)
void	MxCloseAllChannels ()
	Close all mixer channels.
void	MxMixSamples (void *buffer, uint samples)
MixerChannel *	MxAllocateChannel ()
void	MxSetChannelRawSrc (MixerChannel *mc, const std::shared_ptr< std::vector< uint8_t > > &mem, uint rate, bool is16bit)
void	MxSetChannelVolume (MixerChannel *mc, uint volume, float pan)
	Set volume and pan parameters for a sound.
void	MxActivateChannel (MixerChannel *mc)
uint32_t	MxSetMusicSource (MxStreamCallback music_callback)
	Set source of PCM music.
bool	MxInitialize (uint rate)
void	SetEffectVolume (uint8_t volume)

Variables
static std::atomic< MixerChannelMask >	_active_channels
static std::atomic< MixerChannelMask >	_stop_channels
static MixerChannel	_channels [8]
static uint32_t	_play_rate = 11025
static uint32_t	_max_size = UINT_MAX
static MxStreamCallback	_music_stream = nullptr
static std::mutex	_music_stream_mutex
static std::atomic< uint8_t >	_effect_vol
static const int	MAX_VOLUME = 32767
	The theoretical maximum volume for a single sound sample.

Detailed Description

Mixing of sound samples.

Definition in file mixer.cpp.

Typedef Documentation

MixerChannelMask

using MixerChannelMask = uint8_t

Type representing a bitmask of mixer channels.

Definition at line 37 of file mixer.cpp.

Function Documentation

mix_int16()

template<typename T >

static void mix_int16 ( MixerChannel *  sc, int16_t *  buffer, uint  samples, uint8_t  effect_vol  )

static

Definition at line 70 of file mixer.cpp.

MxActivateChannel()

void MxActivateChannel

(

MixerChannel *

mc

)

Definition at line 222 of file mixer.cpp.

MxAllocateChannel()

MixerChannel * MxAllocateChannel

(

)

Definition at line 170 of file mixer.cpp.

MxCloseAllChannels()

void MxCloseAllChannels

(

)

Close all mixer channels.

This signals to the mixer that each channel should be closed even if it has not played all remaining samples. This is safe (and designed) to be called from the main thread.

Definition at line 119 of file mixer.cpp.

Referenced by ChangeSoundSet().

MxCloseChannel()

static void MxCloseChannel ( uint8_t  channel_index )

static

Definition at line 109 of file mixer.cpp.

MxInitialize()

bool MxInitialize

(

uint

rate

)

Definition at line 242 of file mixer.cpp.

MxMixSamples()

void MxMixSamples	(	void *	buffer,
		uint	samples
	)

Definition at line 124 of file mixer.cpp.

MxSetChannelRawSrc()

void MxSetChannelRawSrc	(	MixerChannel *	mc,
		const std::shared_ptr< std::vector< uint8_t > > &	mem,
		uint	rate,
		bool	is16bit
	)

Definition at line 183 of file mixer.cpp.

MxSetChannelVolume()

void MxSetChannelVolume	(	MixerChannel *	mc,
		uint	volume,
		float	pan
	)

Set volume and pan parameters for a sound.

Parameters

mc	MixerChannel to set
volume	Volume level for sound, range is 0..16384
pan	Pan position for sound, range is 0..1

Definition at line 213 of file mixer.cpp.

MxSetMusicSource()

uint32_t MxSetMusicSource

(

MxStreamCallback

music_callback

)

Set source of PCM music.

Parameters

music_callback

Function that will be called to fill sample buffers with music data.

Returns

Sample rate of mixer, which the buffers supplied to the callback must be rendered at.

Definition at line 234 of file mixer.cpp.

References lock.

Referenced by MusicDriver_FluidSynth::Start(), and MusicDriver_FluidSynth::Stop().

RateConversion()

template<typename T >

static int RateConversion ( T *  b, int  frac_pos  )

static

Perform the rate conversion between the input and output.

Parameters

b	the buffer to read the data from
frac_pos	the position from the begin of the buffer till the next element

Template Parameters

T	the size of the buffer (8 or 16 bits)

Returns

the converted value.

Definition at line 64 of file mixer.cpp.

SetEffectVolume()

void SetEffectVolume

(

uint8_t

volume

)

Definition at line 251 of file mixer.cpp.

Variable Documentation

_active_channels

std::atomic<MixerChannelMask> _active_channels

static

Definition at line 39 of file mixer.cpp.

_channels

MixerChannel _channels[8]

static

Definition at line 41 of file mixer.cpp.

_effect_vol

std::atomic<uint8_t> _effect_vol

static

Definition at line 46 of file mixer.cpp.

_max_size

uint32_t _max_size = UINT_MAX

static

Definition at line 43 of file mixer.cpp.

_music_stream

MxStreamCallback _music_stream = nullptr

static

Definition at line 44 of file mixer.cpp.

_music_stream_mutex

std::mutex _music_stream_mutex

static

Definition at line 45 of file mixer.cpp.

_play_rate

uint32_t _play_rate = 11025

static

Definition at line 42 of file mixer.cpp.

_stop_channels

std::atomic<MixerChannelMask> _stop_channels

static

Definition at line 40 of file mixer.cpp.

MAX_VOLUME

const int MAX_VOLUME = 32767

static

The theoretical maximum volume for a single sound sample.

Multiple sound samples should not exceed this limit as it will sound too loud. It also stops overflowing when too many sounds are played at the same time, which causes an even worse sound quality.

Definition at line 54 of file mixer.cpp.