VariableSpeedRingBuffer180< T > Class Template Reference

Variable speed ring buffer with 180-degree phase shifting. More...

#include <PitchShift.h>

Inheritance diagram for VariableSpeedRingBuffer180< T >:

Public Member Functions
	VariableSpeedRingBuffer180 (int size=0, float increment=1.0)
	Constructor.
virtual T *	address ()
	returns the address of the start of the physical read buffer
virtual int	available ()
	provides the number of entries that are available to read
virtual int	availableForWrite ()
	provides the number of entries that are available to write
void	clear ()
	same as reset
virtual int	clearArray (int len)
	Removes the next len entries.
bool	isEmpty ()
virtual bool	isFull ()
	checks if the buffer is full
virtual float	levelPercent ()
	Returns the level of the buffer in %.
bool	peek (T &result)
	Peek operation not supported in this buffer implementation.
bool	read (T &result)
	Read the next pitch-shifted sample.
virtual int	readArray (T data[], int len)
	reads multiple values
void	reset ()
	Reset pointer positions and clear buffer.
bool	resize (int size)
	Resize the internal buffer and recalculate overlap region.
void	setIncrement (float increment)
	Set the pitch shift factor.
size_t	size ()
bool	write (T sample)
	Write a sample to the buffer.
virtual int	writeArray (const T data[], int len)
	Fills the buffer data.
virtual int	writeArrayOverwrite (const T data[], int len)
	Fills the buffer data and overwrites the oldest data if the buffer is full.

Protected Member Functions
virtual T	pitchRead ()
	Core pitch shifting algorithm with 180° phase offset blending.

Protected Attributes
Vector< T >	buffer {0}
int	buffer_size = 0
float	cross_fade = 1.0
int	overlap = 0
float	pitch_shift = 0
float	read_pos_float = 0.0
int	write_pointer = 0
int	write_pos = 0

Detailed Description

template<typename T>
class audio_tools::VariableSpeedRingBuffer180< T >

Variable speed ring buffer with 180-degree phase shifting.

Advanced buffer implementation that reads with 0° and 180° phase offsets and blends the results to prevent overrun artifacts. This technique reduces audio artifacts when read and write pointers collide by cross-fading between two read positions that are 180° apart (half buffer apart).

Based on the algorithm described at: https://github.com/YetAnotherElectronicsChannel/STM32_DSP_PitchShift

Template Parameters

T	The sample data type (typically int16_t or float)

Constructor & Destructor Documentation

VariableSpeedRingBuffer180()

template<typename T >

VariableSpeedRingBuffer180 ( int  size = 0, float  increment = 1.0  )

inline

Constructor.

Parameters

size	Initial buffer size (0 means no allocation yet)
increment	Pitch shift factor (1.0 = no change, >1.0 = higher pitch)

Member Function Documentation

address()

template<typename T >

virtual T * address ( )

inlinevirtual

returns the address of the start of the physical read buffer

Implements BaseBuffer< T >.

available()

template<typename T >

virtual int available ( )

inlinevirtual

provides the number of entries that are available to read

Implements BaseBuffer< T >.

availableForWrite()

template<typename T >

virtual int availableForWrite ( )

inlinevirtual

provides the number of entries that are available to write

Implements BaseBuffer< T >.

clearArray()

template<typename T >

virtual int clearArray ( int  len )

inlinevirtualinherited

Removes the next len entries.

Reimplemented in SingleBuffer< T >, SingleBuffer< float >, SingleBuffer< int16_t >, SingleBuffer< int32_t >, SingleBuffer< stsz_sample_size_t >, SingleBuffer< uint32_t >, and SingleBuffer< uint8_t >.

isFull()

template<typename T >

virtual bool isFull ( )

inlinevirtual

checks if the buffer is full

Reimplemented from BaseBuffer< T >.

peek()

template<typename T >

bool peek ( T &  result )

inlinevirtual

Peek operation not supported in this buffer implementation.

Parameters

result

Unused parameter

Returns

Always returns false (not supported)

Implements BaseBuffer< T >.

pitchRead()

template<typename T >

virtual T pitchRead ( )

inlineprotectedvirtual

Core pitch shifting algorithm with 180° phase offset blending.

This method implements the heart of the pitch shifting algorithm:

1. Creates two read pointers: one at current position, one 180° (half-buffer) away
2. Reads samples from both positions
3. Detects when read pointers approach the write pointer
4. Cross-fades between the two samples to prevent artifacts
5. Advances the read position by the pitch_shift factor

The 180° offset ensures that when one read pointer collides with the write pointer, the other is safely away, allowing smooth transition.

Returns

Pitch-shifted sample with cross-fading applied

read()

template<typename T >

bool read ( T &  result )

inlinevirtual

Read the next pitch-shifted sample.

Parameters

result

Reference to store the processed sample

Returns

true if successful

Implements BaseBuffer< T >.

readArray()

template<typename T >

virtual int readArray ( T  data[], int  len  )

inlinevirtualinherited

reads multiple values

Reimplemented in RingBufferFile< File, T >, BufferRTOS< T >, SynchronizedBuffer< T >, RedisBuffer< T >, BufferRP2040T< T >, NBufferFile< File, T >, and DynamicMultiBuffer< T, BufferType >.

reset()

template<typename T >

void reset ( )

inlinevirtual

Reset pointer positions and clear buffer.

Implements BaseBuffer< T >.

resize()

template<typename T >

bool resize ( int  size )

inlinevirtual

Resize the internal buffer and recalculate overlap region.

Parameters

size	New buffer size in samples

Returns

true if successful

Reimplemented from BaseBuffer< T >.

setIncrement()

template<typename T >

void setIncrement ( float  increment )

inline

Set the pitch shift factor.

Parameters

increment

Pitch shift multiplier (1.0 = no change, >1.0 = higher pitch, <1.0 = lower pitch)

size()

template<typename T >

size_t size ( )

inlinevirtual

Implements BaseBuffer< T >.

write()

template<typename T >

bool write ( T  sample )

inlinevirtual

Write a sample to the buffer.

Parameters

sample

The sample value to write

Returns

true if successful, false if buffer not allocated

Implements BaseBuffer< T >.

writeArray()

template<typename T >

virtual int writeArray ( const T  data[], int  len  )

inlinevirtualinherited

Fills the buffer data.

Reimplemented in BufferRTOS< T >, SynchronizedBuffer< T >, RedisBuffer< T >, BufferRP2040T< T >, SingleBuffer< T >, RingBufferFile< File, T >, NBufferFile< File, T >, and DynamicMultiBuffer< T, BufferType >.

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The documentation for this class was generated from the following file:

• src/AudioTools/CoreAudio/AudioEffects/PitchShift.h