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Standalone: Implemented our own 2 channel panning MixEffect for Stere…
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…o Mode. The built in one does not work when channels are >2. See libsdl-org/SDL_mixer#665
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@superhac
superhac committed Feb 13, 2025
1 parent 45f5db2 commit b1a3878
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Showing 2 changed files with 91 additions and 239 deletions.
324 changes: 90 additions & 234 deletions src/audio/pinsound.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -281,43 +281,25 @@ void PinSound::Play_SNDCFG_SND3D2CH(float nVolume, const float randompitch, cons
float leftVolume;
float rightVolume;

// if(pan != 0) // only if pan is set

// !!!!!! NEED to add global volume for table and bg sounds!!!!!!

PinSound::calcPan(leftVolume, rightVolume, nVolume * 100.0f, pan); // 100f because mix_volume takes ints from 0 - 128


// debug stuff
/* PLOGI << std::fixed << std::setprecision(7) << "Playing Sound: " << m_szName << " SoundOut (0=table, 1=bg): " <<
(int) m_outputTarget << " nVol: " << nVolume << " pan: " << pan <<
" Pitch: "<< pitch << " Random pitch: " << randompitch << " front_rear_fade: " << front_rear_fade << " loopcount: " << loopcount << " usesame: " <<
usesame << " Restart? " << restart; */

if (Mix_Playing(m_assignedChannel)) {
// if(pan != 0)
Mix_SetPanning(m_assignedChannel, leftVolume, rightVolume);
//else
// Mix_Volume(m_assignedChannel, nVolume);

if (restart || !usesame){ // stop and reload
//Mix_FadeOutChannel(m_assignedChannel, 300); // fade out in 300ms. Also halts channel when done
Mix_HaltChannel(m_assignedChannel);
// if(pan != 0)
Mix_SetPanning(m_assignedChannel, leftVolume, rightVolume);
// else
// Mix_Volume(m_assignedChannel, nVolume);
// register the pitch effect. must do this each time before PlayChannel
//Mix_RegisterEffect(m_assignedChannel, PinSound::PitchEffect, nullptr, &m_mixEffectsData);
// register the effects. must do this each time before PlayChannel and once the sound is done its unregistered automaticly
Mix_RegisterEffect(m_assignedChannel, PinSound::Pan2ChannelEffect, nullptr, &m_mixEffectsData);
Mix_PlayChannel(m_assignedChannel, m_pMixChunk, 0);
}
}
else { // not playing
// register the pitch effect. must do this each time before PlayChannel
//Mix_RegisterEffect(m_assignedChannel, PinSound::PitchEffect, nullptr, &m_mixEffectsData);
if(pan != 0)
Mix_SetPanning(m_assignedChannel, leftVolume, rightVolume);
else
Mix_Volume(m_assignedChannel, nVolume);
// register the effects. must do this each time before PlayChannel and once the sound is done its unregistered automaticly
Mix_RegisterEffect(m_assignedChannel, PinSound::Pan2ChannelEffect, nullptr, &m_mixEffectsData);
Mix_PlayChannel(m_assignedChannel, m_pMixChunk, 0);
}
}
Expand Down Expand Up @@ -536,21 +518,24 @@ PinSound *PinSound::LoadFile(const string& strFileName)
//static
void PinSound::calcPan(float& leftPanRatio, float& rightPanRatio, float adjustedVolRatio, float pan)
{
// Normalize pan from range [-3, 3] to [-1, 1]
pan = pan / 3.0f;

// calc pan ratio values for left and right
if (pan < 0.0f) {
// Left is more, right is less
leftPanRatio = adjustedVolRatio * (1.0f + pan); // Adjust so left volume can grow
rightPanRatio = adjustedVolRatio * (1.0f - fabs(pan)); // Decrease right volume as pan goes left
} else {
// Right is more, left is less
leftPanRatio = adjustedVolRatio * (1.0f - pan); // Decrease left volume as pan goes right
rightPanRatio = adjustedVolRatio * (1.0f + pan); // Increase right volume as pan goes right
}
// Normalize pan from range [-3, 3] to [-1, 1]
pan = pan / 3.0f;

//PLOGI << "Pan: " << pan << " AdjustedVolRatio: " << adjustedVolRatio << " left: " << leftPanRatio << " Right Pan: " << rightPanRatio;
// Ensure pan is within -1 to 1 (in case of floating-point errors)
pan = std::clamp(pan, -1.0f, 1.0f);

// Use a more standard panning formula that keeps values within range
float leftFactor = 0.5f * (1.0f - pan); // Left decreases as pan increases
float rightFactor = 0.5f * (1.0f + pan); // Right increases as pan increases

leftPanRatio = adjustedVolRatio * leftFactor;
rightPanRatio = adjustedVolRatio * rightFactor;

// Ensure the values are properly clamped
leftPanRatio = std::clamp(leftPanRatio, 0.0f, 1.0f);
rightPanRatio = std::clamp(rightPanRatio, 0.0f, 1.0f);

//PLOGI << "Pan: " << pan << " AdjustedVolRatio: " << adjustedVolRatio << " Left: " << leftPanRatio << " Right: " << rightPanRatio;
}

//static
Expand Down Expand Up @@ -734,20 +719,77 @@ float PinSound::FadeSSF(float front_rear_fade)
return fabsf(z); // I changed this to get a postive range from 0 to 2.5. not sure why before they returned negative
}

// static
// pans the FL and FR channels. The built in Mix_SetPanning does not work on 2+ channels: https://github.com/libsdl-org/SDL_mixer/issues/665
void PinSound::Pan2ChannelEffect(int chan, void *stream, int len, void *udata) {

MixEffectsData *med = static_cast<MixEffectsData *> (udata);
// pan vols ratios for left and right
float leftPanRatio;
float rightPanRatio;

switch (med->outputFormat)
{
case (SDL_AUDIO_S16LE):
{
int16_t* samples = static_cast<int16_t*>(stream);
int total_samples = len / sizeof(int16_t);
int channels = med->outputChannels;
int frames = total_samples / channels; // Each frame divided by samples

calcPan(leftPanRatio, rightPanRatio, med->nVolume, PinSound::PanSSF(med->pan));

// 8 channels (7.1): FL, FR, FC, LFE, BL, BR, SL, SR
for (int frame = 0; frame < frames; ++frame) {
int index = frame * channels;

// Apply volume gains to Front Left and Right channels
samples[index] = (samples[index] * leftPanRatio); // FL
samples[index + 1] = (samples[index+1] * rightPanRatio); // FR
}
break;
}
case (SDL_AUDIO_F32LE):
{
float* samples = static_cast<float*>(stream);
int total_samples = len / sizeof(float);
int channels = med->outputChannels;
int frames = total_samples / channels; // Each frame has divided by channels

calcPan(leftPanRatio, rightPanRatio, med->nVolume, PinSound::PanSSF(med->pan));

// 8 channels (7.1): FL, FR, FC, LFE, BL, BR, SL, SR
for (int frame = 0; frame < frames; ++frame) {
int index = frame * channels;

// Apply volume gains to Front Left and Right channels
samples[index] = (samples[index] * leftPanRatio); // FL
samples[index + 1] = (samples[index+1] * rightPanRatio); // FR
}
break;
}
default:
{
PLOGE << "unknown audio format..";
return;
}
}
}

// static
void PinSound::SSFEffect(int chan, void *stream, int len, void *udata) {
// 8 channels (7.1): FL, FR, FC, LFE, BL, BR, SL, SR
MixEffectsData *med = static_cast<MixEffectsData *> (udata);

// pan vols ratios for left and right
float leftPanRatio;
float rightPanRatio;
// calc the fade
float sideLeft; // rear of table -1
float sideRight;
float rearLeft; // front of table + 1
float rearRight;
// pan vols ratios for left and right
float leftPanRatio;
float rightPanRatio;

// calc the fade
float sideLeft; // rear of table -1
float sideRight;
float rearLeft; // front of table + 1
float rearRight;

switch (med->outputFormat)
{
Expand Down Expand Up @@ -834,147 +876,8 @@ void PinSound::SSFEffect(int chan, void *stream, int len, void *udata) {
return;
}

void PinSound::WipeAllExceptFront(int chan, void *stream, int len, void *udata) {
MixEffectsData *med = static_cast<MixEffectsData *> (udata);
int16_t* samples = static_cast<int16_t*>(stream);
int total_samples = len / sizeof(int16_t);
int channels = med->outputChannels;
int frames = total_samples / channels; // Each frame has 8 samples (one per channel)


for (int frame = 0; frame < frames; ++frame) {
int index = frame * channels;

// wipe front channels
samples[index+2] = static_cast<int16_t>(0);
samples[index+3] = static_cast<int16_t>(0);
samples[index+4] = static_cast<int16_t>(0);
samples[index+5] = static_cast<int16_t>(0);
samples[index+6] = static_cast<int16_t>(0);
samples[index+7] = static_cast<int16_t>(0);

//PLOGI << "FL: " << samples[index] << " FR: " << samples[index+1] << " FC: " << samples[index+2] << " LFE: " << samples[index+3] << " BL: " << samples[index+4]
// << " BR: " << samples[index+5] << " SR: " << samples[index+6] << " SR: " << samples[index+7] ;
}
}

// Static - adjust pitch function... Called when registered with Mix_RegisterEffect
// from vpinball pitch can be positive or negative and directly adds onto the standard sample frequency
// from vpinball randompitch ranges from 0.0 (no randomization) to 1.0 (vary between half speed to double speed)
void PinSound::PitchEffect(int chan, void *stream, int len, void *udata) {
MixEffectsData* med = static_cast<MixEffectsData*>(udata);
if(med->pitch == 0 && med->randompitch == 0) // no need to resample
return;

float pitchRatio;

if(med->randompitch > 0)
{
const float rndh = rand_mt_01();
const float rndl = rand_mt_01();
int freq = med->outputFrequency + (med->outputFrequency * med->randompitch * rndh * rndh) - (med->outputFrequency *
med->randompitch * rndl * rndl * 0.5f);
pitchRatio = (freq + med->pitch) / med->outputFrequency;

//PLOGI << " random freq = " << freq << " pitchRatio: " << pitchRatio;
}
else // just the pitch value
{
pitchRatio = (med->outputFrequency + med->pitch) / med->outputFrequency;
}

switch(med->outputFormat)
{
case (SDL_AUDIO_S16LE):
{
// Input and output buffer pointers
int16_t *input_samples = static_cast<int16_t *>(stream);
int num_input_samples = len / sizeof(int16_t);

// Output buffer
std::vector<int16_t> output_samples;
output_samples.reserve(static_cast<size_t>(num_input_samples / pitchRatio));

float fractional_pos = 0.0f;

auto cubic_interpolation = [](int16_t y0, int16_t y1, int16_t y2, int16_t y3, float t) -> int16_t {
float a = -0.5f * y0 + 1.5f * y1 - 1.5f * y2 + 0.5f * y3;
float b = y0 - 2.5f * y1 + 2.0f * y2 - 0.5f * y3;
float c = -0.5f * y0 + 0.5f * y2;
float d = y1;
float value = a * t * t * t + b * t * t + c * t + d;

// Clamp to the valid range of int16_t
return static_cast<int16_t>(std::max<float>(-32768.0f, std::min<float>(32767.0f, value)));
};

for (int i = 1; i < num_input_samples - 2; ++i) { // Start at 1 and end at num_input_samples - 2 to ensure we have enough points
fractional_pos += pitchRatio;
while (fractional_pos >= 1.0f) {
fractional_pos -= 1.0f;

// Perform cubic interpolation
int16_t interpolated_sample = cubic_interpolation(
input_samples[i - 1], input_samples[i], input_samples[i + 1], input_samples[i + 2], fractional_pos
);

output_samples.push_back(interpolated_sample);
}
}

// Copy processed output samples back to the stream
std::memset(stream, 0, len); // Clear the buffer first
std::memcpy(stream, output_samples.data(), std::min(len, static_cast<int>(output_samples.size() * sizeof(int16_t))));
break;
}

case(SDL_AUDIO_F32LE):
{
// Input and output buffer pointers
float *input_samples = static_cast<float *>(stream);
int num_input_samples = len / sizeof(float);

// Output buffer
std::vector<float> output_samples;
output_samples.reserve(static_cast<size_t>(num_input_samples / pitchRatio));

float fractional_pos = 0.0f;

auto cubic_interpolation = [](float y0, float y1, float y2, float y3, float t) -> float {
float a = -0.5f * y0 + 1.5f * y1 - 1.5f * y2 + 0.5f * y3;
float b = y0 - 2.5f * y1 + 2.0f * y2 - 0.5f * y3;
float c = -0.5f * y0 + 0.5f * y2;
float d = y1;
return a * t * t * t + b * t * t + c * t + d;
};

for (int i = 1; i < num_input_samples - 2; ++i) { // Start at 1 and end at num_input_samples - 2 to ensure we have enough points
fractional_pos += pitchRatio;
while (fractional_pos >= 1.0f) {
fractional_pos -= 1.0f;

// Perform cubic interpolation
float interpolated_sample = cubic_interpolation(
input_samples[i - 1], input_samples[i], input_samples[i + 1], input_samples[i + 2], fractional_pos
);

output_samples.push_back(interpolated_sample);
}
}

// Copy processed output samples back to the stream
std::memset(stream, 0, len); // Clear the buffer first
std::memcpy(stream, output_samples.data(), std::min(len, static_cast<int>(output_samples.size() * sizeof(float))));
break;
}
default:
{
PLOGE << "Could not identify audio format encoding size. Type: " << med->outputFormat;
return;
}
}
}

// static
// get a sound file's extension
std::string PinSound::getFileExt()
{
const size_t pos = m_szPath.find_last_of('.');
Expand Down Expand Up @@ -1019,53 +922,6 @@ int PinSound::getChannel()
return m_nextAvailableChannel++;
}

// Static
// Calculate the pan volume for each speaker based on the pintable value sent
// from vpiball pan ranges from -1.0 (left) over 0.0 (both) to 1.0 (right)
void PinSound::CalculatePanVolumes(int& leftVolume, int& rightVolume, const float &pan, float baseVolume)
{

float nPan = clamp(pan, 0.0, 1.0);

if (pan > 0) //favor to right
{
if (pan > .000773734f) // all right vol
{
rightVolume = baseVolume;
leftVolume = 0;
}
else if(pan > .0000001f) // 25 percent mark .0000185

{
leftVolume = baseVolume * .25;
rightVolume = baseVolume * .75;
}
else{ // center 50/50
leftVolume = baseVolume / 2;
rightVolume = baseVolume / 2;
}
}
else{ // favor the left
if (pan < - .000773734f) // all left
{
leftVolume = baseVolume;
rightVolume = 0;
}
else if(pan < - .0000185) // 25 percent mark
{
rightVolume = baseVolume * .25;
leftVolume = baseVolume * .75;
}
else{ // center
leftVolume = baseVolume / 2;
rightVolume = baseVolume / 2;
}
}

PLOGI << "volume: " << baseVolume << " pan: " << pan << " nPan: " << nPan
<< " left: " << leftVolume << " right: " << rightVolume;
}

//Static - Returns a vector of audio devices found
void PinSound::EnumerateAudioDevices(vector<AudioDevice>& audioDevices)
{
Expand Down
6 changes: 1 addition & 5 deletions src/audio/pinsound.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -195,16 +195,12 @@ class PinSound
//
static void initSDLAudio();
static int getChannel(); // get a channel assigned for the wav

// calculates the individual volume settings between left and right speakers based on pan ratio
void static CalculatePanVolumes(int& leftVolume, int& rightVolume, const float &pan, float baseVolume);

// Mixer effects (Mix_RegisterEffect) callbacks, and support funcs
void static PitchEffect(int chan, void *stream, int len, void *udata);
void static SSFEffect(int chan, void *stream, int len, void *udata);
void static Pan2ChannelEffect(int chan, void *stream, int len, void *udata);
void static calcPan(float& leftPanRatio, float& rightPanRatio, float adjustedVolRatio, float pan);
void static calcFade(float leftPanRatio, float rightPanRatio, float fadeRatio, float& frontLeft, float& frontRight, float& rearLeft, float& rearRight);
void static WipeAllExceptFront(int chan, void *stream, int len, void *udata);
float static PanSSF(float pan);
float static FadeSSF(float front_rear_fade);

Expand Down

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