AudioFifo Class Reference

Lock-free audio FIFO buffer for single producer/consumer scenarios. More...

#include <gin_audiofifo.h>

Public Member Functions
	AudioFifo (int channels=2, int numSamples=128)
	Creates an AudioFifo with the specified number of channels and sample capacity.
void	setSize (int numChannels, int numSamples)
	Resizes the FIFO to a new capacity.
int	getNumChannels () const noexcept
	Returns the number of audio channels.
int	getFreeSpace () const noexcept
	Returns the number of samples that can be written before the FIFO is full.
int	getNumReady () const noexcept
	Returns the number of samples available to read.
void	reset () noexcept
	Resets the FIFO to an empty state.
void	ensureFreeSpace (int numSamples)
	Ensures at least the specified amount of free space by discarding oldest data if needed.
bool	write (const juce::AudioSampleBuffer &src, int numSamples=-1)
	Writes audio data from an AudioSampleBuffer to the FIFO.
bool	write (const float *const *data, int numSamples, int numChannels=-1)
	Writes audio data from a multi-channel array to the FIFO.
bool	writeSilence (int numSamples)
	Writes silence (zeros) to the FIFO.
bool	writeMono (const float *data, int numSamples)
	Writes mono audio data to a single-channel FIFO.
bool	peek (juce::AudioSampleBuffer &dest)
	Peeks at (reads without consuming) audio data from the FIFO.
bool	peek (juce::AudioSampleBuffer &dest, int startSampleInDestBuffer, int numSamples)
	Peeks at (reads without consuming) audio data from the FIFO.
float	peekSample (int channel, int sample)
	Peeks at a single sample without consuming it.
bool	read (juce::AudioSampleBuffer &dest)
	Reads and removes audio data from the FIFO.
bool	read (juce::AudioSampleBuffer &dest, int startSampleInDestBuffer, int numSamples)
	Reads and removes audio data from the FIFO.
bool	readMono (float *data, int numSamples)
	Reads and removes mono audio data from a single-channel FIFO.
bool	readAdding (juce::AudioSampleBuffer &dest)
	Reads and removes audio data from the FIFO, adding it to the destination buffer.
bool	readAdding (juce::AudioSampleBuffer &dest, int startSampleInDestBuffer, int numSamples)
	Reads and removes audio data from the FIFO, adding it to the destination buffer.
bool	pop (int numSamples)
	Removes (discards) samples from the FIFO without reading them.

Detailed Description

Lock-free audio FIFO buffer for single producer/consumer scenarios.

AudioFifo provides a thread-safe circular buffer for passing audio between threads, typically from an audio callback to a background processing thread or vice versa. It uses JUCE's AbstractFifo for lock-free operation with a single producer and single consumer thread.

Key Features:

• Lock-free for single producer/consumer (real-time safe)
• Multi-channel audio support
• Read/write operations with optional adding
• Peek operations (read without consuming)
• Silence writing
• Automatic space management

Common Use Cases:

• Passing audio from real-time thread to UI analyzer
• Buffering between processing stages
• Circular recording buffer
• Audio preview/monitoring

Thread Safety:

• Safe for ONE producer thread and ONE consumer thread
• NOT safe for multiple producers or multiple consumers
• Write operations must be on one thread only
• Read operations must be on one thread only

Usage:

AudioFifo fifo(2, 4096); // 2 channels, 4096 samples
 
// In audio thread (producer)
if (fifo.getFreeSpace() >= buffer.getNumSamples())
    fifo.write(buffer);
 
// In background thread (consumer)
if (fifo.getNumReady() >= desiredSamples)
{
    AudioBuffer<float> output(2, desiredSamples);
    fifo.read(output);
    // ... process output
}

See also

MidiFifo, AudioMidiFifo, ResamplingFifo

Constructor & Destructor Documentation

AudioFifo()

AudioFifo::AudioFifo	(	int	channels = 2,
		int	numSamples = 128 )

Creates an AudioFifo with the specified number of channels and sample capacity.

Parameters

channels	Number of audio channels (default: 2)
numSamples	Maximum number of samples the FIFO can hold (default: 128)

Member Function Documentation

setSize()

void AudioFifo::setSize	(	int	numChannels,
		int	numSamples )

Resizes the FIFO to a new capacity.

Note: This is not thread-safe and should only be called when no other threads are accessing the FIFO.

Parameters

numChannels	New number of audio channels
numSamples	New maximum number of samples

getNumChannels()

int AudioFifo::getNumChannels ( ) const

noexcept

Returns the number of audio channels.

getFreeSpace()

int AudioFifo::getFreeSpace ( ) const

noexcept

Returns the number of samples that can be written before the FIFO is full.

Referenced by ensureFreeSpace(), write(), writeMono(), and writeSilence().

getNumReady()

int AudioFifo::getNumReady ( ) const

noexcept

Returns the number of samples available to read.

Referenced by ensureFreeSpace(), peek(), peekSample(), pop(), read(), readAdding(), and readMono().

reset()

void AudioFifo::reset ( )

noexcept

Resets the FIFO to an empty state.

Note: This is not thread-safe and should only be called when no other threads are accessing the FIFO.

ensureFreeSpace()

void AudioFifo::ensureFreeSpace

(

int

numSamples

)

Ensures at least the specified amount of free space by discarding oldest data if needed.

If the requested free space is greater than currently available, this will discard the oldest samples to make room.

Parameters

numSamples

The minimum number of free samples required

References getFreeSpace(), and getNumReady().

write() [1/2]

bool AudioFifo::write	(	const juce::AudioSampleBuffer &	src,
		int	numSamples = -1 )

Writes audio data from an AudioSampleBuffer to the FIFO.

Should only be called from the producer thread.

Parameters

src	The source buffer to write from
numSamples	Number of samples to write (default: -1 writes all samples from src)

Returns

true if successful, false if there wasn't enough space

References write().

Referenced by write().

write() [2/2]

bool AudioFifo::write	(	const float *const *	data,
		int	numSamples,
		int	numChannels = -1 )

Writes audio data from a multi-channel array to the FIFO.

Should only be called from the producer thread.

Parameters

data	Array of channel pointers containing the audio data
numSamples	Number of samples to write
numChannels	Number of valid channel pointers in data, or -1 if it matches the FIFO's channel count. If fewer than the FIFO's channel count, the extra FIFO channels are filled with silence.

Returns

true if successful, false if there wasn't enough space

References getFreeSpace().

writeSilence()

bool AudioFifo::writeSilence

(

int

numSamples

)

Writes silence (zeros) to the FIFO.

Should only be called from the producer thread.

Parameters

numSamples

Number of silent samples to write

Returns

true if successful, false if there wasn't enough space

References getFreeSpace().

writeMono()

bool AudioFifo::writeMono	(	const float *	data,
		int	numSamples )

Writes mono audio data to a single-channel FIFO.

Should only be called from the producer thread. The FIFO must be configured for single-channel (mono) operation.

Parameters

data	Pointer to the mono audio data
numSamples	Number of samples to write

Returns

true if successful, false if there wasn't enough space

References getFreeSpace().

peek() [1/2]

bool AudioFifo::peek

(

juce::AudioSampleBuffer &

dest

)

Peeks at (reads without consuming) audio data from the FIFO.

The data remains in the FIFO and can be read again. Should only be called from the consumer thread.

Parameters

dest	Destination buffer to copy the audio data into

Returns

true if successful, false if there weren't enough samples available

References peek().

Referenced by peek().

peek() [2/2]

bool AudioFifo::peek	(	juce::AudioSampleBuffer &	dest,
		int	startSampleInDestBuffer,
		int	numSamples )

Peeks at (reads without consuming) audio data from the FIFO.

The data remains in the FIFO and can be read again. Should only be called from the consumer thread.

Parameters

dest	Destination buffer to copy the audio data into
startSampleInDestBuffer	Starting position in the destination buffer
numSamples	Number of samples to peek

Returns

true if successful, false if there weren't enough samples available

References getNumReady().

peekSample()

float AudioFifo::peekSample	(	int	channel,
		int	sample )

Peeks at a single sample without consuming it.

Should only be called from the consumer thread.

Parameters

channel	The channel to peek from
sample	The sample index to peek (0 = first available sample)

Returns

The sample value at the specified position

References getNumReady().

read() [1/2]

bool AudioFifo::read

(

juce::AudioSampleBuffer &

dest

)

Reads and removes audio data from the FIFO.

Should only be called from the consumer thread.

Parameters

dest	Destination buffer to copy the audio data into

Returns

true if successful, false if there weren't enough samples available

References read().

Referenced by read().

read() [2/2]

bool AudioFifo::read	(	juce::AudioSampleBuffer &	dest,
		int	startSampleInDestBuffer,
		int	numSamples )

Reads and removes audio data from the FIFO.

Should only be called from the consumer thread.

Parameters

dest	Destination buffer to copy the audio data into
startSampleInDestBuffer	Starting position in the destination buffer
numSamples	Number of samples to read

Returns

true if successful, false if there weren't enough samples available

References getNumReady().

readMono()

bool AudioFifo::readMono	(	float *	data,
		int	numSamples )

Reads and removes mono audio data from a single-channel FIFO.

Should only be called from the consumer thread. The FIFO must be configured for single-channel (mono) operation.

Parameters

data	Pointer to the destination array for the audio data
numSamples	Number of samples to read

Returns

true if successful, false if there weren't enough samples available

References getNumReady().

readAdding() [1/2]

bool AudioFifo::readAdding

(

juce::AudioSampleBuffer &

dest

)

Reads and removes audio data from the FIFO, adding it to the destination buffer.

Unlike read(), this adds the FIFO data to the destination rather than replacing it. Should only be called from the consumer thread.

Parameters

dest	Destination buffer to add the audio data to

Returns

true if successful, false if there weren't enough samples available

References readAdding().

Referenced by readAdding().

readAdding() [2/2]

bool AudioFifo::readAdding	(	juce::AudioSampleBuffer &	dest,
		int	startSampleInDestBuffer,
		int	numSamples )

Reads and removes audio data from the FIFO, adding it to the destination buffer.

Unlike read(), this adds the FIFO data to the destination rather than replacing it. Should only be called from the consumer thread.

Parameters

dest	Destination buffer to add the audio data to
startSampleInDestBuffer	Starting position in the destination buffer
numSamples	Number of samples to read

Returns

true if successful, false if there weren't enough samples available

References getNumReady().

pop()

bool AudioFifo::pop

(

int

numSamples

)

Removes (discards) samples from the FIFO without reading them.

This is useful after peek() operations when you want to consume the peeked data. Should only be called from the consumer thread.

Parameters

numSamples

Number of samples to discard

Returns

true if successful, false if there weren't enough samples available

References getNumReady().

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

• gin_audiofifo.h