Added downmixing of surround for stereo output devices

Audio/Chain/ConverterNode.h

@@ -16,9 +16,14 @@
 
 @interface ConverterNode : Node {
 	AudioConverterRef converter;
+    AudioConverterRef converterDownmix;
 	void *callbackBuffer;
+    
+    void *downmixBuffer;
+    int downmixSize, downmixOffset;
 	
 	AudioStreamBasicDescription inputFormat;
+    AudioStreamBasicDescription downmixFormat;
 	AudioStreamBasicDescription outputFormat;
 }
 

Audio/Chain/ConverterNode.m

@@ -28,6 +28,53 @@ void PrintStreamDesc (AudioStreamBasicDescription *inDesc)
 
 @implementation ConverterNode
 
+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},{0.3943F,0.2277F},
+        {0.2277F,0.3943F},{0.2788F,0.2788F}
+    },
+    /*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(float * buffer, int channels, int count)
+{
+    if (channels >= 3 && channels < 8)
+    for (int i = 0; i < count; ++i)
+    {
+        float left = 0, right = 0;
+        for (int j = 0; j < channels; ++j)
+        {
+            left += buffer[i * channels + j] * STEREO_DOWNMIX[channels - 3][j][0];
+            right += buffer[i * channels + j] * STEREO_DOWNMIX[channels - 3][j][1];
+        }
+        buffer[i * channels + 0] = left;
+        buffer[i * channels + 1] = right;
+    }
+}
+
 //called from the complexfill when the audio is converted...good clean fun
 static OSStatus ACInputProc(AudioConverterRef inAudioConverter, UInt32* ioNumberDataPackets, AudioBufferList* ioData, AudioStreamPacketDescription** outDataPacketDescription, void* inUserData)
 {
@@ -58,7 +105,7 @@ static OSStatus ACInputProc(AudioConverterRef inAudioConverter, UInt32* ioNumber
 		
 		return 100; //Keep asking for data
 	}
-
+    
 	ioData->mBuffers[0].mData = converter->callbackBuffer;
 	ioData->mBuffers[0].mDataByteSize = amountRead;
 	ioData->mBuffers[0].mNumberChannels = (converter->inputFormat.mChannelsPerFrame);
@@ -67,6 +114,35 @@ static OSStatus ACInputProc(AudioConverterRef inAudioConverter, UInt32* ioNumber
 	return err;
 }
 
+static OSStatus ACDownmixProc(AudioConverterRef inAudioConverter, UInt32* ioNumberDataPackets, AudioBufferList* ioData, AudioStreamPacketDescription** outDataPacketDescription, void* inUserData)
+{
+	ConverterNode *converter = (ConverterNode *)inUserData;
+	OSStatus err = noErr;
+	int amountToWrite;
+	
+	if ([converter shouldContinue] == NO || [converter endOfStream] == YES)
+	{
+		ioData->mBuffers[0].mDataByteSize = 0;
+		*ioNumberDataPackets = 0;
+        
+		return noErr;
+	}
+	
+	amountToWrite = (*ioNumberDataPackets)*(converter->downmixFormat.mBytesPerPacket);
+
+    if ( amountToWrite + converter->downmixOffset > converter->downmixSize )
+        amountToWrite = converter->downmixSize - converter->downmixOffset;
+    
+	ioData->mBuffers[0].mData = converter->downmixBuffer + converter->downmixOffset;
+	ioData->mBuffers[0].mDataByteSize = amountToWrite;
+	ioData->mBuffers[0].mNumberChannels = (converter->downmixFormat.mChannelsPerFrame);
+	ioData->mNumberBuffers = 1;
+	
+    converter->downmixOffset += amountToWrite;
+    
+	return err;
+}
+
 -(void)process
 {
 	char writeBuf[CHUNK_SIZE];	
@@ -83,23 +159,88 @@ static OSStatus ACInputProc(AudioConverterRef inAudioConverter, UInt32* ioNumber
 	AudioBufferList ioData;
 	UInt32 ioNumberFrames;
 	OSStatus err;
+    int amountRead = 0;
 	
-	ioNumberFrames = amount/outputFormat.mBytesPerFrame;
+    if ( converterDownmix )
-	ioData.mBuffers[0].mData = dest;
+    {
-	ioData.mBuffers[0].mDataByteSize = amount;
+        if (downmixOffset == downmixSize) {
-	ioData.mBuffers[0].mNumberChannels = outputFormat.mChannelsPerFrame;
+            ioNumberFrames = amount / outputFormat.mBytesPerFrame;
-	ioData.mNumberBuffers = 1;
+            
+            downmixBuffer = realloc( downmixBuffer, ioNumberFrames * downmixFormat.mBytesPerFrame );
+            ioData.mBuffers[0].mData = downmixBuffer;
+            ioData.mBuffers[0].mDataByteSize = ioNumberFrames * downmixFormat.mBytesPerFrame;
+            ioData.mBuffers[0].mNumberChannels = downmixFormat.mChannelsPerFrame;
+            ioData.mNumberBuffers = 1;
+            
+        tryagain:
+            err = AudioConverterFillComplexBuffer(converter, ACInputProc, self, &ioNumberFrames, &ioData, NULL);
+            amountRead += ioData.mBuffers[0].mDataByteSize;
+            if (err == 100)
+            {
+                NSLog(@"INSIZE: %i", amountRead);
+                ioData.mBuffers[0].mData = downmixBuffer + amountRead;
+                ioNumberFrames = ( amount / outputFormat.mBytesPerFrame ) - ( amountRead / downmixFormat.mBytesPerFrame );
+                ioData.mBuffers[0].mDataByteSize = ioNumberFrames * downmixFormat.mBytesPerFrame;
+                goto tryagain;
+            }
+            else if (err != noErr)
+            {
+                NSLog(@"Error: %i", err);
+            }
+            
+            downmix_to_stereo( (float*) downmixBuffer, downmixFormat.mChannelsPerFrame, amountRead / downmixFormat.mBytesPerFrame );
+        
+            downmixSize = amountRead;
+            downmixOffset = 0;
+        }
+        
+        ioNumberFrames = amount / outputFormat.mBytesPerFrame;
+        ioData.mBuffers[0].mData = dest;
+        ioData.mBuffers[0].mDataByteSize = amount;
+        ioData.mBuffers[0].mNumberChannels = outputFormat.mChannelsPerFrame;
+        ioData.mNumberBuffers = 1;
+
+        amountRead = 0;
+        
+    tryagain2:
+        err = AudioConverterFillComplexBuffer(converterDownmix,  ACDownmixProc, self, &ioNumberFrames, &ioData, NULL);
+        amountRead += ioData.mBuffers[0].mDataByteSize;
+        if (err == 100)
+        {
+            NSLog(@"INSIZE: %i", amountRead);
+            ioData.mBuffers[0].mData = dest + amountRead;
+            ioNumberFrames = ( amount - amountRead ) / outputFormat.mBytesPerFrame;
+            ioData.mBuffers[0].mDataByteSize = ioNumberFrames * outputFormat.mBytesPerFrame;
+            goto tryagain2;
+        }
+        else if (err != noErr && err != kAudioConverterErr_InvalidInputSize)
+        {
+            NSLog(@"Error: %i", err);
+        }
+    }
+    else
+    {
+        ioNumberFrames = amount/outputFormat.mBytesPerFrame;
+        ioData.mBuffers[0].mData = dest;
+        ioData.mBuffers[0].mDataByteSize = amount;
+        ioData.mBuffers[0].mNumberChannels = outputFormat.mChannelsPerFrame;
+        ioData.mNumberBuffers = 1;
 	
-	err = AudioConverterFillComplexBuffer(converter, ACInputProc, self, &ioNumberFrames, &ioData, NULL);
+    tryagain3:
-	int amountRead = ioData.mBuffers[0].mDataByteSize;
+        err = AudioConverterFillComplexBuffer(converter, ACInputProc, self, &ioNumberFrames, &ioData, NULL);
-	if (err == kAudioConverterErr_InvalidInputSize) //It returns insz at EOS at times...so run it again to make sure all data is converted
+        amountRead += ioData.mBuffers[0].mDataByteSize;
-	{
+        if (err == 100) //It returns insz at EOS at times...so run it again to make sure all data is converted
-		NSLog(@"INSIZE: %i", amountRead);
+        {
-		amountRead += [self convert:dest + amountRead amount:amount - amountRead];
+            NSLog(@"INSIZE: %i", amountRead);
-	}
+            ioData.mBuffers[0].mData = dest + amountRead;
-	else if (err != noErr && err != 100) {
+            ioNumberFrames = ( amount - amountRead ) / outputFormat.mBytesPerFrame;
-		NSLog(@"Error: %i", err);
+            ioData.mBuffers[0].mDataByteSize = ioNumberFrames * outputFormat.mBytesPerFrame;
-	}
+            goto tryagain3;
+        }
+        else if (err != noErr) {
+            NSLog(@"Error: %i", err);
+        }
+    }
 	
 	return amountRead;
 }
@@ -112,11 +253,41 @@ static OSStatus ACInputProc(AudioConverterRef inAudioConverter, UInt32* ioNumber
 	inputFormat = inf;
 	outputFormat = outf;
 
-	stat = AudioConverterNew ( &inputFormat, &outputFormat, &converter);
+    if (inputFormat.mChannelsPerFrame > 2 && outputFormat.mChannelsPerFrame == 2)
-	if (stat != noErr)
+    {
-	{
+        downmixFormat = inputFormat;
-		NSLog(@"Error creating converter %i", stat);
+        downmixFormat.mFormatFlags = kAudioFormatFlagsNativeFloatPacked;
-	}	
+        downmixFormat.mBitsPerChannel = 32;
+        downmixFormat.mBytesPerFrame = (32/8)*downmixFormat.mChannelsPerFrame;
+        downmixFormat.mBytesPerPacket = downmixFormat.mBytesPerFrame * downmixFormat.mFramesPerPacket;
+        stat = AudioConverterNew( &inputFormat, &downmixFormat, &converter );
+        if (stat != noErr)
+        {
+            NSLog(@"Error creating converter %i", stat);
+        }
+        stat = AudioConverterNew ( &downmixFormat, &outputFormat, &converterDownmix );
+        if (stat != noErr)
+        {
+            NSLog(@"Error creating converter %i", stat);
+        }
+            
+        SInt32 channelMap[2] = { 0, 1 };
+        
+		stat = AudioConverterSetProperty(converterDownmix,kAudioConverterChannelMap,sizeof(channelMap),channelMap);
+		if (stat != noErr)
+		{
+			NSLog(@"Error mapping channels %i", stat);
+		}
+    }
+    else
+    {
+
+        stat = AudioConverterNew ( &inputFormat, &outputFormat, &converter);
+        if (stat != noErr)
+        {
+            NSLog(@"Error creating converter %i", stat);
+        }
+    }
 	
 	if (inputFormat.mChannelsPerFrame == 1)
 	{
@@ -158,11 +329,21 @@ static OSStatus ACInputProc(AudioConverterRef inAudioConverter, UInt32* ioNumber
 
 - (void)cleanUp
 {
+    if (converterDownmix)
+    {
+        AudioConverterDispose(converterDownmix);
+        converterDownmix = NULL;
+    }
 	if (converter)
 	{
 		AudioConverterDispose(converter);
 		converter = NULL;
 	}
+    if (downmixBuffer)
+    {
+        free(downmixBuffer);
+        downmixBuffer = NULL;
+    }
 	if (callbackBuffer) {
 		free(callbackBuffer);
 		callbackBuffer = NULL;