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Cog/Audio/Chain/Downmix.m
Christopher Snowhill 637ea4efe1 Core Audio output: Rewrote major portions 
After all this rewriting, down or upmixing the audio is now handled with
the lowest latency possible, meaning that toggling the HRIR option now
takes effect immediately.

Signed-off-by: Christopher Snowhill <kode54@gmail.com>
2022-02-05 03:45:02 -08:00

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//
// Downmix.m
// Cog
//
// Created by Christopher Snowhill on 2/05/22.
// Copyright 2022 __LoSnoCo__. All rights reserved.
//
#import "Downmix.h"
#import "Logging.h"
static const float STEREO_DOWNMIX[8-2][8][2]={
/*3.0*/
{
{0.5858F,0.0F},{0.0F,0.5858F},{0.4142F,0.4142F}
},
/*quadrophonic*/
{
{0.4226F,0.0F},{0.0F,0.4226F},{0.366F,0.2114F},{0.2114F,0.336F}
},
/*5.0*/
{
{0.651F,0.0F},{0.0F,0.651F},{0.46F,0.46F},{0.5636F,0.3254F},
{0.3254F,0.5636F}
},
/*5.1*/
{
{0.529F,0.0F},{0.0F,0.529F},{0.3741F,0.3741F},{0.3741F,0.3741F},{0.4582F,0.2645F},
{0.2645F,0.4582F}
},
/*6.1*/
{
{0.4553F,0.0F},{0.0F,0.4553F},{0.322F,0.322F},{0.322F,0.322F},{0.2788F,0.2788F},
{0.3943F,0.2277F},{0.2277F,0.3943F}
},
/*7.1*/
{
{0.3886F,0.0F},{0.0F,0.3886F},{0.2748F,0.2748F},{0.2748F,0.2748F},{0.3366F,0.1943F},
{0.1943F,0.3366F},{0.3366F,0.1943F},{0.1943F,0.3366F}
}
};
static void downmix_to_stereo(const float * inBuffer, int channels, float * outBuffer, size_t count)
{
if (channels >= 3 && channels <= 8)
for (size_t i = 0; i < count; ++i)
{
float left = 0, right = 0;
for (int j = 0; j < channels; ++j)
{
left += inBuffer[i * channels + j] * STEREO_DOWNMIX[channels - 3][j][0];
right += inBuffer[i * channels + j] * STEREO_DOWNMIX[channels - 3][j][1];
}
outBuffer[i * 2 + 0] = left;
outBuffer[i * 2 + 1] = right;
}
}
static void downmix_to_mono(const float * inBuffer, int channels, float * outBuffer, size_t count)
{
float tempBuffer[count * 2];
if (channels >= 3 && channels <= 8)
{
downmix_to_stereo(inBuffer, channels, tempBuffer, count);
inBuffer = tempBuffer;
channels = 2;
}
float invchannels = 1.0 / (float)channels;
for (size_t i = 0; i < count; ++i)
{
float sample = 0;
for (int j = 0; j < channels; ++j)
{
sample += inBuffer[i * channels + j];
}
outBuffer[i] = sample * invchannels;
}
}
static void upmix(const float * inBuffer, int inchannels, float * outBuffer, int outchannels, size_t count)
{
for (ssize_t i = 0; i < count; ++i)
{
if (inchannels == 1 && outchannels == 2)
{
// upmix mono to stereo
float sample = inBuffer[i];
outBuffer[i * 2 + 0] = sample;
outBuffer[i * 2 + 1] = sample;
}
else if (inchannels == 1 && outchannels == 4)
{
// upmix mono to quad
float sample = inBuffer[i];
outBuffer[i * 4 + 0] = sample;
outBuffer[i * 4 + 1] = sample;
outBuffer[i * 4 + 2] = 0;
outBuffer[i * 4 + 3] = 0;
}
else if (inchannels == 1 && (outchannels == 3 || outchannels >= 5))
{
// upmix mono to center channel
float sample = inBuffer[i];
outBuffer[i * outchannels + 2] = sample;
for (int j = 0; j < 2; ++j)
{
outBuffer[i * outchannels + j] = 0;
}
for (int j = 3; j < outchannels; ++j)
{
outBuffer[i * outchannels + j] = 0;
}
}
else if (inchannels == 4 && outchannels >= 5)
{
float fl = inBuffer[i * 4 + 0];
float fr = inBuffer[i * 4 + 1];
float bl = inBuffer[i * 4 + 2];
float br = inBuffer[i * 4 + 3];
const int skipclfe = (outchannels == 5) ? 1 : 2;
outBuffer[i * outchannels + 0] = fl;
outBuffer[i * outchannels + 1] = fr;
outBuffer[i * outchannels + skipclfe + 2] = bl;
outBuffer[i * outchannels + skipclfe + 3] = br;
for (int j = 0; j < skipclfe; ++j)
{
outBuffer[i * outchannels + 2 + j] = 0;
}
for (int j = 4 + skipclfe; j < outchannels; ++j)
{
outBuffer[i * outchannels + j] = 0;
}
}
else if (inchannels == 5 && outchannels >= 6)
{
float fl = inBuffer[i * 5 + 0];
float fr = inBuffer[i * 5 + 1];
float c = inBuffer[i * 5 + 2];
float bl = inBuffer[i * 5 + 3];
float br = inBuffer[i * 5 + 4];
outBuffer[i * outchannels + 0] = fl;
outBuffer[i * outchannels + 1] = fr;
outBuffer[i * outchannels + 2] = c;
outBuffer[i * outchannels + 3] = 0;
outBuffer[i * outchannels + 4] = bl;
outBuffer[i * outchannels + 5] = br;
for (int j = 6; j < outchannels; ++j)
{
outBuffer[i * outchannels + j] = 0;
}
}
else if (inchannels == 7 && outchannels == 8)
{
float fl = inBuffer[i * 7 + 0];
float fr = inBuffer[i * 7 + 1];
float c = inBuffer[i * 7 + 2];
float lfe = inBuffer[i * 7 + 3];
float sl = inBuffer[i * 7 + 4];
float sr = inBuffer[i * 7 + 5];
float bc = inBuffer[i * 7 + 6];
outBuffer[i * 8 + 0] = fl;
outBuffer[i * 8 + 1] = fr;
outBuffer[i * 8 + 2] = c;
outBuffer[i * 8 + 3] = lfe;
outBuffer[i * 8 + 4] = bc;
outBuffer[i * 8 + 5] = bc;
outBuffer[i * 8 + 6] = sl;
outBuffer[i * 8 + 7] = sr;
}
else
{
// upmix N channels to N channels plus silence the empty channels
float samples[inchannels];
for (int j = 0; j < inchannels; ++j)
{
samples[j] = inBuffer[i * inchannels + j];
}
for (int j = 0; j < inchannels; ++j)
{
outBuffer[i * outchannels + j] = samples[j];
}
for (int j = inchannels; j < outchannels; ++j)
{
outBuffer[i * outchannels + j] = 0;
}
}
}
}
@implementation DownmixProcessor
- (id) initWithInputFormat:(AudioStreamBasicDescription)inf andOutputFormat:(AudioStreamBasicDescription)outf {
self = [super init];
if (self) {
if (inf.mFormatID != kAudioFormatLinearPCM ||
(inf.mFormatFlags & kAudioFormatFlagsNativeFloatPacked) != kAudioFormatFlagsNativeFloatPacked ||
inf.mBitsPerChannel != 32 ||
inf.mBytesPerFrame != (4 * inf.mChannelsPerFrame) ||
inf.mBytesPerPacket != inf.mFramesPerPacket * inf.mBytesPerFrame)
return nil;
if (outf.mFormatID != kAudioFormatLinearPCM ||
(outf.mFormatFlags & kAudioFormatFlagsNativeFloatPacked) != kAudioFormatFlagsNativeFloatPacked ||
outf.mBitsPerChannel != 32 ||
outf.mBytesPerFrame != (4 * outf.mChannelsPerFrame) ||
outf.mBytesPerPacket != outf.mFramesPerPacket * outf.mBytesPerFrame)
return nil;
inputFormat = inf;
outputFormat = outf;
[self setupVirt];
[[NSUserDefaultsController sharedUserDefaultsController] addObserver:self forKeyPath:@"values.headphoneVirtualization" options:0 context:nil];
[[NSUserDefaultsController sharedUserDefaultsController] addObserver:self forKeyPath:@"values.hrirPath" options:0 context:nil];
}
return self;
}
- (void) dealloc {
[[NSUserDefaultsController sharedUserDefaultsController] removeObserver:self forKeyPath:@"values.headphoneVirtualization"];
[[NSUserDefaultsController sharedUserDefaultsController] removeObserver:self forKeyPath:@"values.hrirPath"];
}
- (void) setupVirt {
@synchronized(hFilter) {
hFilter = nil;
}
BOOL hVirt = [[[NSUserDefaultsController sharedUserDefaultsController] defaults] boolForKey:@"headphoneVirtualization"];
if (hVirt &&
outputFormat.mChannelsPerFrame == 2 &&
inputFormat.mChannelsPerFrame >= 1 &&
inputFormat.mChannelsPerFrame <= 8) {
NSString * userPreset = [[[NSUserDefaultsController sharedUserDefaultsController] defaults] stringForKey:@"hrirPath"];
NSURL * presetUrl = nil;
if (userPreset && ![userPreset isEqualToString:@""]) {
presetUrl = [NSURL fileURLWithPath:userPreset];
if (![HeadphoneFilter validateImpulseFile:presetUrl])
presetUrl = nil;
}
if (!presetUrl) {
presetUrl = [[NSBundle mainBundle] URLForResource:@"gsx" withExtension:@"wv"];
if (![HeadphoneFilter validateImpulseFile:presetUrl])
presetUrl = nil;
}
if (presetUrl) {
@synchronized(hFilter) {
hFilter = [[HeadphoneFilter alloc] initWithImpulseFile:presetUrl forSampleRate:outputFormat.mSampleRate withInputChannels:inputFormat.mChannelsPerFrame];
}
}
}
}
- (void)observeValueForKeyPath:(NSString *)keyPath
ofObject:(id)object
change:(NSDictionary *)change
context:(void *)context
{
DLog(@"SOMETHING CHANGED!");
if ([keyPath isEqualToString:@"values.headphoneVirtualization"] ||
[keyPath isEqualToString:@"values.hrirPath"]) {
// Reset the converter, without rebuffering
[self setupVirt];
}
}
- (void) process:(const void *)inBuffer frameCount:(size_t)frames output:(void *)outBuffer {
@synchronized (hFilter) {
if ( hFilter ) {
[hFilter process:(const float *) inBuffer sampleCount:frames toBuffer:(float *) outBuffer];
return;
}
}
if ( inputFormat.mChannelsPerFrame > 2 && outputFormat.mChannelsPerFrame == 2 )
{
downmix_to_stereo( (const float*) inBuffer, inputFormat.mChannelsPerFrame, (float*) outBuffer, frames );
}
else if ( inputFormat.mChannelsPerFrame > 1 && outputFormat.mChannelsPerFrame == 1 )
{
downmix_to_mono( (const float*) inBuffer, inputFormat.mChannelsPerFrame, (float*) outBuffer, frames );
}
else if ( inputFormat.mChannelsPerFrame < outputFormat.mChannelsPerFrame )
{
upmix( (const float*) inBuffer, inputFormat.mChannelsPerFrame, (float*) outBuffer, outputFormat.mChannelsPerFrame, frames );
}
else if ( inputFormat.mChannelsPerFrame == outputFormat.mChannelsPerFrame )
{
memcpy(outBuffer, inBuffer, frames * outputFormat.mBytesPerPacket);
}
}
@end
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