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

Functions
template<typename T >
static int	RateConversion (T *b, int frac_pos)
	Perform the rate conversion between the input and output. More...
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. More...
void	MxMixSamples (void *buffer, uint samples)
MixerChannel *	MxAllocateChannel ()
void	MxSetChannelRawSrc (MixerChannel *mc, int8_t *mem, size_t size, uint rate, bool is16bit)
void	MxSetChannelVolume (MixerChannel *mc, uint volume, float pan)
	Set volume and pan parameters for a sound. More...
void	MxActivateChannel (MixerChannel *mc)
uint32_t	MxSetMusicSource (MxStreamCallback music_callback)
	Set source of PCM music. More...
bool	MxInitialize (uint rate)
void	SetEffectVolume (uint8_t volume)

Variables
static std::atomic< uint8_t >	_active_channels
static std::atomic< uint8_t >	_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. More...

Detailed Description

Mixing of sound samples.

Definition in file mixer.cpp.

Function Documentation

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 117 of file mixer.cpp.

Referenced by ChangeSoundSet().

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 208 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 229 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 62 of file mixer.cpp.

Variable Documentation

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 52 of file mixer.cpp.