diff --git a/src/add-ons/media/media-add-ons/mixer/AudioMixer.cpp b/src/add-ons/media/media-add-ons/mixer/AudioMixer.cpp
index 736a4d8ddf..cb8b8b7031 100644
--- a/src/add-ons/media/media-add-ons/mixer/AudioMixer.cpp
+++ b/src/add-ons/media/media-add-ons/mixer/AudioMixer.cpp
@@ -465,19 +465,19 @@ AudioMixer::FormatChangeRequested(const media_source &source, const media_destin
 	//printf("AudioMixer: SendLatencyChange %Ld\n", EventLatency());
 	//SendLatencyChange(source, destination, EventLatency());
 
-	delete fBufferGroup;
-	fBufferGroup = CreateBufferGroup();
-	fCore->SetOutputBufferGroup(fBufferGroup);
-	
 	// apply latency change
 	fCore->SetTimingInfo(TimeSource(), fDownstreamLatency);
 
 	// apply format change
 	fCore->OutputFormatChanged(io_format->u.raw_audio);
 
+	delete fBufferGroup;
+	fBufferGroup = CreateBufferGroup();
+	fCore->SetOutputBufferGroup(fBufferGroup);
+
 	fCore->Unlock();
 	return B_OK;
-
+	
 err:
 	fCore->Unlock();
 	return B_ERROR;
diff --git a/src/add-ons/media/media-add-ons/mixer/MixerCore.cpp b/src/add-ons/media/media-add-ons/mixer/MixerCore.cpp
index e8732176eb..7fa011a495 100644
--- a/src/add-ons/media/media-add-ons/mixer/MixerCore.cpp
+++ b/src/add-ons/media/media-add-ons/mixer/MixerCore.cpp
@@ -204,7 +204,7 @@ MixerCore::ApplyOutputFormat()
 		
 	delete fMixBufferChannelTypes;
 
-	fMixBufferFrameRate = (int32)format.frame_rate;
+	fMixBufferFrameRate = (int32)(0.5 + format.frame_rate);
 	fMixBufferFrameCount = frames_per_buffer(format);
 	if (fDoubleRateMixing) {
 		fMixBufferFrameRate *= 2;
diff --git a/src/add-ons/media/media-add-ons/mixer/MixerInput.cpp b/src/add-ons/media/media-add-ons/mixer/MixerInput.cpp
index 6b82500c7e..619112b338 100644
--- a/src/add-ons/media/media-add-ons/mixer/MixerInput.cpp
+++ b/src/add-ons/media/media-add-ons/mixer/MixerInput.cpp
@@ -189,6 +189,12 @@ MixerInput::ID()
 	return fInput.destination.id;
 }
 
+uint32
+MixerInput::GetInputChannelCount()
+{
+	return fInputChannelCount;
+}
+
 void
 MixerInput::AddInputChannelDesignation(int channel, uint32 des)
 {
@@ -385,19 +391,6 @@ MixerInput::GetMixerChannelCount()
 	return fMixerChannelCount;
 }
 
-void
-MixerInput::GetMixerChannelInfo(int channel, int64 framepos, const float **buffer, uint32 *sample_offset, int *type, float *gain)
-{
-	ASSERT(fMixBuffer); // this function should not be called if we don't have a mix buffer!
-	ASSERT(channel >= 0 && channel < fMixerChannelCount);
-	int32 offset = framepos % fMixBufferFrameCount;
-	if (channel == 0) PRINT(3, "GetMixerChannelInfo: frames %ld to %ld\n", offset, offset + debugMixBufferFrames - 1);
-	*buffer = reinterpret_cast<float *>(reinterpret_cast<char *>(fMixerChannelInfo[channel].buffer_base) + (offset * sizeof(float) * fInputChannelCount));
-	*sample_offset = sizeof(float) * fInputChannelCount;
-	*type = fMixerChannelInfo[channel].type;
-	*gain = fMixerChannelInfo[channel].gain;
-}
-
 void
 MixerInput::SetMixerChannelGain(int channel, float gain)
 {
diff --git a/src/add-ons/media/media-add-ons/mixer/MixerInput.h b/src/add-ons/media/media-add-ons/mixer/MixerInput.h
index 1c10ff0261..31ee9bd7ee 100644
--- a/src/add-ons/media/media-add-ons/mixer/MixerInput.h
+++ b/src/add-ons/media/media-add-ons/mixer/MixerInput.h
@@ -1,6 +1,8 @@
 #ifndef _MIXER_INPUT_H
 #define _MIXER_INPUT_H
 
+#include "debug.h"
+
 class MixerCore;
 class ByteSwap;
 class Resampler;
@@ -18,10 +20,10 @@ public:
 	media_input & MediaInput();
 	
 	uint32 GetMixerChannelCount();
-	void GetMixerChannelInfo(int channel, int64 framepos, const float **buffer, uint32 *sample_offset, int *type, float *gain);
 	void SetMixerChannelGain(int channel, float gain);
 	float GetMixerChannelGain(int channel);
 	
+	uint32 GetInputChannelCount();
 	void AddInputChannelDesignation(int channel, uint32 des);
 	void RemoveInputChannelDesignation(int channel, uint32 des);
 	uint32 GetInputChannelDesignations(int channel);
@@ -29,6 +31,10 @@ public:
 	void SetInputChannelGain(int channel, float gain);
 	float GetInputChannelGain(int channel);
 
+	// only for use by MixerCore
+	void GetMixerChannelInfo(int channel, int64 framepos, const float **buffer, uint32 *sample_offset, int *type, float *gain);
+	int GetMixerChannelType(int channel);
+
 protected:
 	friend class MixerCore;
 	void SetMixBufferFormat(int32 framerate, int32 frames);
@@ -74,4 +80,25 @@ private:
 	int32			debugMixBufferFrames;
 };
 
+inline void
+MixerInput::GetMixerChannelInfo(int channel, int64 framepos, const float **buffer, uint32 *sample_offset, int *type, float *gain)
+{
+	ASSERT(fMixBuffer); // this function should not be called if we don't have a mix buffer!
+	ASSERT(channel >= 0 && channel < fMixerChannelCount);
+	int32 offset = framepos % fMixBufferFrameCount;
+	if (channel == 0) PRINT(3, "GetMixerChannelInfo: frames %ld to %ld\n", offset, offset + debugMixBufferFrames - 1);
+	*buffer = reinterpret_cast<float *>(reinterpret_cast<char *>(fMixerChannelInfo[channel].buffer_base) + (offset * sizeof(float) * fInputChannelCount));
+	*sample_offset = sizeof(float) * fInputChannelCount;
+	*type = fMixerChannelInfo[channel].type;
+	*gain = fMixerChannelInfo[channel].gain;
+}
+
+inline int
+MixerInput::GetMixerChannelType(int channel)
+{
+	ASSERT(fMixBuffer); // this function should not be called if we don't have a mix buffer!
+	ASSERT(channel >= 0 && channel < fMixerChannelCount);
+	return fMixerChannelInfo[channel].type;
+}
+
 #endif
diff --git a/src/add-ons/media/media-add-ons/mixer/MixerOutput.cpp b/src/add-ons/media/media-add-ons/mixer/MixerOutput.cpp
index b8b2e353ff..e3f39eed78 100644
--- a/src/add-ons/media/media-add-ons/mixer/MixerOutput.cpp
+++ b/src/add-ons/media/media-add-ons/mixer/MixerOutput.cpp
@@ -6,15 +6,20 @@
 
 MixerOutput::MixerOutput(MixerCore *core, const media_output &output)
  :	fCore(core),
-	fOutput(output)
+	fOutput(output),
+	fOutputChannelCount(0),
+	fOutputChannelInfo(0)
 {
 	fix_multiaudio_format(&fOutput.format.u.raw_audio);
 	PRINT_OUTPUT("MixerOutput::MixerOutput", fOutput);
 	PRINT_CHANNEL_MASK(fOutput.format);
+
+	UpdateOutputChannels();
 }
 
 MixerOutput::~MixerOutput()
 {
+	delete fOutputChannelInfo;
 }
 
 media_output &
@@ -31,4 +36,148 @@ MixerOutput::ChangeFormat(const media_multi_audio_format &format)
 	
 	PRINT_OUTPUT("MixerOutput::ChangeFormat", fOutput);
 	PRINT_CHANNEL_MASK(fOutput.format);
+
+	UpdateOutputChannels();
+}
+
+void
+MixerOutput::UpdateOutputChannels()
+{
+	output_chan_info *oldInfo = fOutputChannelInfo;
+	uint32 oldCount = fOutputChannelCount;
+
+	fOutputChannelCount = fOutput.format.u.raw_audio.channel_count;
+	fOutputChannelInfo = new output_chan_info[fOutputChannelCount];
+	for (int i = 0; i < fOutputChannelCount; i++) {
+		fOutputChannelInfo[i].designation = GetChannelMask(i, fOutput.format.u.raw_audio.channel_mask);
+		fOutputChannelInfo[i].gain = 1.0;
+		fOutputChannelInfo[i].source_count = 1;
+		fOutputChannelInfo[i].source_gain[0] = 1.0;
+		fOutputChannelInfo[i].source_type[0] = ChannelMaskToChannelType(fOutputChannelInfo[i].designation);
+	}
+	AssignDefaultSources();
+	
+	// apply old gains and sources, overriding the 1.0 gain defaults for the old channels
+	if (oldInfo != 0 && oldCount != 0) {
+		for (int i = 0; i < fOutputChannelCount; i++) {
+			for (int j = 0; j < oldCount; j++) {
+				if (fOutputChannelInfo[i].designation == oldInfo[j].designation) {
+					fOutputChannelInfo[i].gain == oldInfo[j].gain;
+					fOutputChannelInfo[i].source_count == oldInfo[j].source_count;
+					for (int k = 0; k < fOutputChannelInfo[i].source_count; k++) {
+						fOutputChannelInfo[i].source_gain[k] == oldInfo[j].source_gain[k];
+						fOutputChannelInfo[i].source_type[k] == oldInfo[j].source_type[k];
+					}
+					break;
+				}
+			}
+		}
+		// also delete the old info array
+		delete [] oldInfo;
+	}
+	for (int i = 0; i < fOutputChannelCount; i++)
+		printf("UpdateOutputChannels: output channel %d, des 0x%08X (type %2d), gain %.3f\n", i, fOutputChannelInfo[i].designation, ChannelMaskToChannelType(fOutputChannelInfo[i].designation), fOutputChannelInfo[i].gain);
+}
+
+void
+MixerOutput::AssignDefaultSources()
+{
+	// XXX assign default sources
+	for (int i = 0; i < fOutputChannelCount; i++) {
+		for (int j = 0; j < fOutputChannelInfo[i].source_count; j++) {
+			printf("AssignDefaultSources: output channel %d, source %d: des 0x%08X (type %2d), gain %.3f\n", i, j, ChannelTypeToChannelMask(fOutputChannelInfo[i].source_type[j]), fOutputChannelInfo[i].source_type[j], fOutputChannelInfo[i].source_gain[j]);
+		}
+	}
+}
+
+uint32
+MixerOutput::GetOutputChannelDesignation(int channel)
+{
+	if (channel < 0 || channel >= fOutputChannelCount)
+		return 0;
+	return fOutputChannelInfo[channel].designation;
+}
+
+void
+MixerOutput::SetOutputChannelGain(int channel, float gain)
+{
+	if (channel < 0 || channel >= fOutputChannelCount)
+		return;
+	fOutputChannelInfo[channel].gain = gain;
+}
+
+void
+MixerOutput::AddOutputChannelSource(int channel, uint32 source_designation, float source_gain)
+{
+	if (channel < 0 || channel >= fOutputChannelCount)
+		return;
+	if (fOutputChannelInfo[channel].source_count == MAX_SOURCES)
+		return;
+	int source_type = ChannelMaskToChannelType(source_designation);
+	for (int i = 0; i < fOutputChannelInfo[channel].source_count; i++) {
+		if (fOutputChannelInfo[channel].source_type[i] == source_type)
+			return;
+	}
+	fOutputChannelInfo[channel].source_type[fOutputChannelInfo[channel].source_count] = source_type;
+	fOutputChannelInfo[channel].source_gain[fOutputChannelInfo[channel].source_count] = source_gain;
+	fOutputChannelInfo[channel].source_count++;
+}
+
+void
+MixerOutput::RemoveOutputChannelSource(int channel, uint32 source_designation)
+{
+	if (channel < 0 || channel >= fOutputChannelCount)
+		return;
+	int source_type = ChannelMaskToChannelType(source_designation);
+	for (int i = 0; i < fOutputChannelInfo[channel].source_count; i++) {
+		if (fOutputChannelInfo[channel].source_type[i] == source_type) {
+			fOutputChannelInfo[channel].source_type[i] = fOutputChannelInfo[channel].source_type[fOutputChannelInfo[channel].source_count - 1];
+			fOutputChannelInfo[channel].source_gain[i] = fOutputChannelInfo[channel].source_gain[fOutputChannelInfo[channel].source_count - 1];
+			fOutputChannelInfo[channel].source_count--;
+			return;
+		}
+	}
+}
+
+void
+MixerOutput::SetOutputChannelSourceGain(int channel, uint32 source_designation, float source_gain)
+{
+	if (channel < 0 || channel >= fOutputChannelCount)
+		return;
+	int source_type = ChannelMaskToChannelType(source_designation);
+	for (int i = 0; i < fOutputChannelInfo[channel].source_count; i++) {
+		if (fOutputChannelInfo[channel].source_type[i] == source_type) {
+			fOutputChannelInfo[channel].source_gain[i] = source_gain;
+			return;
+		}
+	}
+}
+
+float
+MixerOutput::GetOutputChannelSourceGain(int channel, uint32 source_designation)
+{
+	if (channel < 0 || channel >= fOutputChannelCount)
+		return 1.0;
+	int source_type = ChannelMaskToChannelType(source_designation);
+	for (int i = 0; i < fOutputChannelInfo[channel].source_count; i++) {
+		if (fOutputChannelInfo[channel].source_type[i] == source_type) {
+			return fOutputChannelInfo[channel].source_gain[i];
+		}
+	}
+	return 1.0;
+}
+
+void
+MixerOutput::GetOutputChannelSourceAt(int channel, int index, uint32 *source_designation, float *source_gain)
+{
+	if (channel < 0 || channel >= fOutputChannelCount)
+		return;
+	if (index >= fOutputChannelInfo[channel].source_count) {
+		// ERROR
+		*source_gain = 1.0;
+		*source_designation = 0;
+		return;
+	}
+	*source_gain = fOutputChannelInfo[channel].source_gain[index];
+	*source_designation = ChannelTypeToChannelMask(fOutputChannelInfo[channel].source_type[index]);
 }
diff --git a/src/add-ons/media/media-add-ons/mixer/MixerOutput.h b/src/add-ons/media/media-add-ons/mixer/MixerOutput.h
index 19f15b6b05..3db8625f83 100644
--- a/src/add-ons/media/media-add-ons/mixer/MixerOutput.h
+++ b/src/add-ons/media/media-add-ons/mixer/MixerOutput.h
@@ -1,6 +1,10 @@
 #ifndef _MIXER_OUTPUT_H
 #define _MIXER_OUTPUT_H
 
+#include "debug.h"
+
+#define MAX_SOURCES 20
+
 class MixerCore;
 
 class MixerOutput
@@ -13,9 +17,66 @@ public:
 	
 	void ChangeFormat(const media_multi_audio_format &format);
 	
+	uint32 GetOutputChannelCount();
+	uint32 GetOutputChannelDesignation(int channel);
+	void SetOutputChannelGain(int channel, float gain);
+	float GetOutputChannelGain(int channel);
+	
+	uint32 GetOutputChannelSourceCount(int channel);
+	void AddOutputChannelSource(int channel, uint32 source_designation, float source_gain);
+	void RemoveOutputChannelSource(int channel, uint32 source_designation);
+	void SetOutputChannelSourceGain(int channel, uint32 source_designation, float source_gain);
+	float GetOutputChannelSourceGain(int channel, uint32 source_designation);
+	void GetOutputChannelSourceAt(int channel, int index, uint32 *source_designation, float *source_gain);
+
+	// only for use by MixerCore
+	void GetMixerChannelInfo(int channel, int index, int *type, float *gain);
+
 private:
-	MixerCore *fCore;
-	media_output fOutput;
+	void UpdateOutputChannels();
+	void AssignDefaultSources();
+	
+private:
+	struct output_chan_info {
+		uint32 designation;	// only one bit set
+		float gain;
+		int source_count;
+		float source_gain[MAX_SOURCES];
+		int source_type[MAX_SOURCES];
+	};	
+
+	MixerCore 			*fCore;
+	media_output 		fOutput;
+	
+	uint32				fOutputChannelCount;
+	output_chan_info 	*fOutputChannelInfo; //array
 };
 
+inline uint32 MixerOutput::GetOutputChannelCount()
+{
+	return fOutputChannelCount;
+}
+
+inline float MixerOutput::GetOutputChannelGain(int channel)
+{
+	if (channel < 0 || channel >= fOutputChannelCount)
+		return 1.0;
+	return fOutputChannelInfo[channel].gain;
+}
+
+inline uint32 MixerOutput::GetOutputChannelSourceCount(int channel)
+{
+	if (channel < 0 || channel >= fOutputChannelCount)
+		return 0;
+	return fOutputChannelInfo[channel].source_count;
+}
+
+inline void MixerOutput::GetMixerChannelInfo(int channel, int index, int *type, float *gain)
+{
+	ASSERT (channel >= 0 && channel < fOutputChannelCount);
+	ASSERT(index >= 0 && index < fOutputChannelInfo[channel].source_count);
+	*type = fOutputChannelInfo[channel].source_type[index];
+	*gain = fOutputChannelInfo[channel].source_gain[index];
+}
+
 #endif