#import <Foundation/Foundation.h>
#import <AudioToolbox/AudioToolbox.h>
#import "AEAudioBufferListUtilities.h"

Macros
#define	AEDSPSilence AEAudioBufferListSilence
	Silence an audio buffer list (zero out frames)

Functions
void	AEDSPApplyGain (const AudioBufferList *bufferList, float gain, UInt32 frames)
	Scale values in a buffer list by some gain value.

void	AEDSPApplyRamp (const AudioBufferList bufferList, float start, float step, UInt32 frames)
	Apply a ramp to values in a buffer list.

void	AEDSPApplyEqualPowerRamp (const AudioBufferList bufferList, float start, float step, UInt32 frames, float *scratch)
	Apply an equal-power ramp to values in a buffer list.

void	AEDSPApplyGainSmoothed (const AudioBufferList bufferList, float targetGain, float currentGain, UInt32 frames)
	Scale values in a buffer list by some gain value, with smoothing to avoid discontinuities.

void	AEDSPApplyGainWithRamp (const AudioBufferList bufferList, float targetGain, float currentGain, UInt32 frames, UInt32 rampDuration)
	Scale values in a buffer list by some gain value, with smoothing to avoid discontinuities.

void	AEDSPApplyGainSmoothedMono (float buffer, float targetGain, float currentGain, UInt32 frames)
	Scale values in a single buffer by some gain value, with smoothing to avoid discontinuities.

void	AEDSPApplyVolumeAndBalance (const AudioBufferList bufferList, float targetVolume, float currentVolume, float targetBalance, float *currentBalance, UInt32 frames)
	Apply volume and balance controls to the buffer.

void	AEDSPMix (const AudioBufferList bufferList1, const AudioBufferList bufferList2, float gain1, float gain2, BOOL monoToStereo, UInt32 frames, const AudioBufferList *output)
	Mix two buffer lists.

void	AEDSPMixMono (const float buffer1, const float buffer2, float gain1, float gain2, UInt32 frames, float *output)
	Mix two single mono buffers.

Macro Definition Documentation

#define AEDSPSilence AEAudioBufferListSilence

Silence an audio buffer list (zero out frames)

Parameters

bufferList	Pointer to an AudioBufferList containing audio
offset	Offset into buffer
length	Number of frames to silence (0 for whole buffer)

Function Documentation

void AEDSPApplyGain	(	const AudioBufferList *	bufferList,
		float	gain,
		UInt32	frames
	)

Scale values in a buffer list by some gain value.

Parameters

bufferList	Audio buffer list, in non-interleaved float format
gain	Gain amount (power ratio)
frames	Length of buffer in frames

void AEDSPApplyRamp	(	const AudioBufferList *	bufferList,
		float *	start,
		float	step,
		UInt32	frames
	)

Apply a ramp to values in a buffer list.

Parameters

bufferList	Audio buffer list, in non-interleaved float format
start	Starting gain (power ratio) on input; final gain value on output
step	Amount per frame to advance gain
frames	Length of buffer in frames

void AEDSPApplyEqualPowerRamp	(	const AudioBufferList *	bufferList,
		float *	start,
		float	step,
		UInt32	frames,
		float *	scratch
	)

Apply an equal-power ramp to values in a buffer list.

This uses a quarter-cycle cosine ramp envelope to preserve the power level, useful when crossfading two signals without causing a bump in gain in the middle of the fade.

Parameters

bufferList	Audio buffer list, in non-interleaved float format
start	Starting gain (power ratio) on input; final gain value on output
step	Amount per frame to advance gain
frames	Length of buffer in frames
scratch	A scratch buffer to use, or NULL to use an internal buffer. Not thread-safe if the latter is used.

void AEDSPApplyGainSmoothed	(	const AudioBufferList *	bufferList,
		float	targetGain,
		float *	currentGain,
		UInt32	frames
	)

Scale values in a buffer list by some gain value, with smoothing to avoid discontinuities.

Parameters

bufferList	Audio buffer list, in non-interleaved float format
targetGain	Target gain amount (power ratio)
currentGain	On input, current gain; on output, the new gain. Store this and pass it back to this function on successive calls for a smooth ramp
frames	Length of buffer in frames

void AEDSPApplyGainWithRamp	(	const AudioBufferList *	bufferList,
		float	targetGain,
		float *	currentGain,
		UInt32	frames,
		UInt32	rampDuration
	)

Scale values in a buffer list by some gain value, with smoothing to avoid discontinuities.

Parameters

bufferList	Audio buffer list, in non-interleaved float format
targetGain	Target gain amount (power ratio)
currentGain	On input, current gain; on output, the new gain. Store this and pass it back to this function on successive calls for a smooth ramp
frames	Length of buffer in frames
rampDuration	Duration of full 0.0-1.0/1.0-0.0 transition, in frames

void AEDSPApplyGainSmoothedMono	(	float *	buffer,
		float	targetGain,
		float *	currentGain,
		UInt32	frames
	)

Scale values in a single buffer by some gain value, with smoothing to avoid discontinuities.

Parameters

buffer	Float array
targetGain	Target gain amount (power ratio)
currentGain	On input, current gain; on output, the new gain
frames	Length of buffer in frames

void AEDSPApplyVolumeAndBalance	(	const AudioBufferList *	bufferList,
		float	targetVolume,
		float *	currentVolume,
		float	targetBalance,
		float *	currentBalance,
		UInt32	frames
	)

Apply volume and balance controls to the buffer.

This function applies gains to the given buffer to affect volume and balance, with a smoothing ramp applied to avoid discontinuities.

Parameters

bufferList	Audio buffer list, in non-interleaved float format
targetVolume	The target volume (power ratio)
currentVolume	On input, the current volume; on output, the new volume. Store this and pass it back to this function on successive calls for a smooth ramp. If NULL, no smoothing will be applied.
targetBalance	The target balance
currentBalance	On input, the current balance; on output, the new balance. Store this and pass it back to this function on successive calls for a smooth ramp. If NULL, no smoothing will be applied.
frames	Length of buffer in frames

void AEDSPMix	(	const AudioBufferList *	bufferList1,
		const AudioBufferList *	bufferList2,
		float	gain1,
		float	gain2,
		BOOL	monoToStereo,
		UInt32	frames,
		const AudioBufferList *	output
	)

Mix two buffer lists.

Combines values in each buffer list, after scaling by given factors. If monoToStereo is YES, then if a buffer is mono, and the output is stereo, the buffer will have its channels doubled If the output is mono, any buffers with more channels will have these mixed down into the mono output.

This method assumes the number of frames in each buffer is the same.

Note that input buffer contents may be modified during this operation.

Parameters

bufferList1	First buffer list, in non-interleaved float format
bufferList2	Second buffer list, in non-interleaved float format
gain1	Gain factor for first buffer list (power ratio)
gain2	Gain factor for second buffer list
monoToStereo	Whether to double mono tracks to stereo, if output is stereo
frames	Length of buffer in frames, or 0 for entire buffer (based on mDataByteSize fields)
output	Output buffer list (may be same as bufferList1 or bufferList2)

void AEDSPMixMono	(	const float *	buffer1,
		const float *	buffer2,
		float	gain1,
		float	gain2,
		UInt32	frames,
		float *	output
	)

Mix two single mono buffers.

Parameters

buffer1	First buffer
buffer2	Second buffer
gain1	Gain factor for first buffer (power ratio)
gain2	Gain factor for second buffer
frames	Number of frames
output	Output buffer

Macros

Functions

Macro Definition Documentation

Function Documentation