Live audio recording and playback implementation. More...

#include "liveio.h"

Include dependency graph for liveio.c:

Data Structures
struct	LA_simpleData
	Simple audio buffer with read/write positions. More...

Functions
double	LA_get_cur_record_time (void)
	Get the current time (in seconds) of the recording stream.

double	LA_get_cur_play_time (void)
	Get the current time (in seconds) of the playback stream.

void	LA_stop_recording (void)
	Stop the current recording.

void	LA_stop_playing (void)
	Stop the current playback.

int	LA_is_recording (void)
	Check if the recording stream is currently active.

int	LA_is_playing (void)
	Check if the playback stream is currently active.

static int	_ContinuousRecordCallback (const void inputBuffer, void outputBuffer, unsigned long framesPerBuffer, const PaStreamCallbackTimeInfo timeInfo, PaStreamCallbackFlags statusFlags, void userData)
	Callback for continuous (circular buffer) recording.

static int	_RecordCallback (const void inputBuffer, void outputBuffer, unsigned long framesPerBuffer, const PaStreamCallbackTimeInfo timeInfo, PaStreamCallbackFlags statusFlags, void userData)
	Callback for one-shot recording (fill the buffer once, then stop).

static int	_PlayCallback (const void inputBuffer, void outputBuffer, unsigned long framesPerBuffer, const PaStreamCallbackTimeInfo timeInfo, PaStreamCallbackFlags statusFlags, void userData)
	Callback for playback: reads mono samples and duplicates them to both stereo output channels (left and right get the same data).

static void	_RecordStreamFinished (void *userData)
	Called by PortAudio when a one-shot recording stream finishes.

static void	_PlayStreamFinished (void *userData)
	Called by PortAudio when a playback stream finishes.

static LaError_t	_ensure_init (void)
	Auto-initialise PortAudio if not already done.

static LaError_t	_setup_input_params (PaStreamParameters *p)
	Configure mono 16-bit input parameters for the default device.

static LaError_t	_setup_output_params (PaStreamParameters *p)
	Configure stereo 16-bit output parameters for the default device.

LaError_t	LA_record_callback (unsigned samprate, PaStreamCallback cb, void cb_data)
	Record using a user-supplied PortAudio callback function.

LaError_t	LA_record (void *buffer, unsigned long bufsize, unsigned samprate, int rectype)
	Record audio from the default input device into a buffer.

LaError_t	LA_play_callback (unsigned samprate, PaStreamCallback cb, void cb_data)
	Play using a user-supplied PortAudio callback function.

LaError_t	LA_play (const void *buffer, unsigned long bufsize, unsigned samprate)
	Play audio from a buffer to the default output device.

void	LA_print_last_error (FILE *stream)
	Print the last PortAudio error message to the given stream.

LaError_t	LA_init (void)
	Initialise the PortAudio system.

LaError_t	LA_terminate (void)
	Terminate the PortAudio system and release resources.

Variables
static int	LA_InitDone = 0
	Has PA been initialised?

static PaError	LA_LastError = paNoError
	Most recent PA error code.

static PaStream *	LA_PlayStream = nullptr
	Active playback stream

static PaStream *	LA_RecordStream = nullptr
	Active recording stream

static LA_simpleData	LA_data
	Shared buffer descriptor

Detailed Description

Live audio recording and playback implementation.

Author: Chuck Wooters woote.nosp@m.rs@h.nosp@m.ey.co.nosp@m.m

This is a wrapper around PortAudio (http://portaudio.com), a cross-platform library for real-time audio I/O.

PortAudio works on a callback model: you give it a function, and it calls that function whenever it needs more audio data (for playback) or has new data available (for recording). The callbacks run on a separate high-priority thread managed by the OS audio subsystem.

Definition in file liveio.c.

Function Documentation

◆ _ContinuousRecordCallback()

static int _ContinuousRecordCallback	(	const void *	inputBuffer,
		void *	outputBuffer,
		unsigned long	framesPerBuffer,
		const PaStreamCallbackTimeInfo *	timeInfo,
		PaStreamCallbackFlags	statusFlags,
		void *	userData
	)

static

Callback for continuous (circular buffer) recording.

When the write position reaches the end of the buffer, it wraps around to the beginning. This means old data is overwritten – the buffer always contains the most recent audio.

Definition at line 115 of file liveio.c.

◆ _ensure_init()

static LaError_t _ensure_init ( void )

static

Auto-initialise PortAudio if not already done.

Definition at line 252 of file liveio.c.

◆ _PlayCallback()

static int _PlayCallback	(	const void *	inputBuffer,
		void *	outputBuffer,
		unsigned long	framesPerBuffer,
		const PaStreamCallbackTimeInfo *	timeInfo,
		PaStreamCallbackFlags	statusFlags,
		void *	userData
	)

static

Callback for playback: reads mono samples and duplicates them to both stereo output channels (left and right get the same data).

Definition at line 188 of file liveio.c.

◆ _PlayStreamFinished()

static void _PlayStreamFinished ( void * userData )

static

Called by PortAudio when a playback stream finishes.

Closes the stream so resources are released.

Definition at line 238 of file liveio.c.

◆ _RecordCallback()

static int _RecordCallback	(	const void *	inputBuffer,
		void *	outputBuffer,
		unsigned long	framesPerBuffer,
		const PaStreamCallbackTimeInfo *	timeInfo,
		PaStreamCallbackFlags	statusFlags,
		void *	userData
	)

static

Callback for one-shot recording (fill the buffer once, then stop).

Returns paComplete when the buffer is full, which tells PortAudio to stop the stream after this callback returns.

Definition at line 147 of file liveio.c.

◆ _RecordStreamFinished()

static void _RecordStreamFinished ( void * userData )

static

Called by PortAudio when a one-shot recording stream finishes.

Closes the stream so resources are released.

Definition at line 225 of file liveio.c.

◆ _setup_input_params()

static LaError_t _setup_input_params ( PaStreamParameters * p )

static

Configure mono 16-bit input parameters for the default device.

Definition at line 261 of file liveio.c.

◆ _setup_output_params()

static LaError_t _setup_output_params ( PaStreamParameters * p )

static

Configure stereo 16-bit output parameters for the default device.

Definition at line 276 of file liveio.c.

◆ LA_get_cur_play_time()

double LA_get_cur_play_time ( void )

Get the current time (in seconds) of the playback stream.

Returns -1.0 if inactive.

Definition at line 57 of file liveio.c.

◆ LA_get_cur_record_time()

double LA_get_cur_record_time ( void )

Get the current time (in seconds) of the recording stream.

Returns -1.0 if inactive.

Definition at line 49 of file liveio.c.

◆ LA_init()

LaError_t LA_init ( void )

Initialise the PortAudio system.

If already initialised, terminates first and re-initialises.

Returns: LA_OK on success, LA_ERROR on failure.

Definition at line 420 of file liveio.c.

◆ LA_is_playing()

int LA_is_playing ( void )

Check if the playback stream is currently active.

Check if the playback stream is active.

Returns: 1 if playing, 0 if not, -1 on error.

Definition at line 94 of file liveio.c.

◆ LA_is_recording()

int LA_is_recording ( void )

Check if the recording stream is currently active.

Check if the recording stream is active.

Returns: 1 if recording, 0 if not, -1 on error.

Definition at line 83 of file liveio.c.

◆ LA_play()

LaError_t LA_play	(	const void *	buffer,
		unsigned long	bufsize,
		unsigned	samprate
	)

Play audio from a buffer to the default output device.

Parameters

buffer	Buffer of 16-bit signed integers.
bufsize	Number of samples in the buffer.
samprate	Sampling rate in Hz.

Returns: LA_OK on success, LA_ERROR on failure.

Note: Non-blocking: returns immediately while playback continues in the background. Mono input is duplicated to both stereo channels.

Definition at line 378 of file liveio.c.

◆ LA_play_callback()

LaError_t LA_play_callback	(	unsigned	samprate,
		PaStreamCallback *	cb,
		void *	cb_data
	)

Play using a user-supplied PortAudio callback function.

Parameters

samprate	Sampling rate in Hz.
cb	Your PortAudio callback function.
cb_data	Data pointer passed to your callback.

Returns: LA_OK on success, LA_ERROR on failure.

Definition at line 358 of file liveio.c.

◆ LA_print_last_error()

void LA_print_last_error ( FILE * stream )

Print the last PortAudio error message to the given stream.

Definition at line 409 of file liveio.c.

◆ LA_record()

LaError_t LA_record	(	void *	buffer,
		unsigned long	bufsize,
		unsigned	samprate,
		int	rectype
	)

Record audio from the default input device into a buffer.

Parameters

buffer	Pre-allocated buffer of 16-bit signed integers.
bufsize	Number of samples the buffer can hold.
samprate	Desired sampling rate in Hz (e.g. 16000, 44100).
rectype	LA_REC_ONCE (fill buffer then stop) or LA_REC_CONT (circular).

Returns: LA_OK on success, LA_ERROR on failure.

Note: Non-blocking: returns immediately while recording continues in the background.

Definition at line 314 of file liveio.c.

◆ LA_record_callback()

LaError_t LA_record_callback	(	unsigned	samprate,
		PaStreamCallback *	cb,
		void *	cb_data
	)

Record using a user-supplied PortAudio callback function.

Parameters

samprate	Sampling rate in Hz.
cb	Your PortAudio callback function.
cb_data	Data pointer passed to your callback.

Returns: LA_OK on success, LA_ERROR on failure.

Definition at line 294 of file liveio.c.

◆ LA_stop_playing()

void LA_stop_playing ( void )

Stop the current playback.

Definition at line 72 of file liveio.c.

◆ LA_stop_recording()

void LA_stop_recording ( void )

Stop the current recording.

Definition at line 65 of file liveio.c.

◆ LA_terminate()

LaError_t LA_terminate ( void )

Terminate the PortAudio system and release resources.

Shut down the PortAudio system.

Returns: LA_OK on success, LA_ERROR on failure.

Definition at line 441 of file liveio.c.

Variable Documentation

◆ LA_data

LA_simpleData LA_data

static

Shared buffer descriptor

Definition at line 43 of file liveio.c.

◆ LA_InitDone

int LA_InitDone = 0

static

Has PA been initialised?

Definition at line 39 of file liveio.c.

◆ LA_LastError

PaError LA_LastError = paNoError

static

Most recent PA error code.

Definition at line 40 of file liveio.c.

◆ LA_PlayStream

PaStream* LA_PlayStream = nullptr

static

Active playback stream

Definition at line 41 of file liveio.c.

◆ LA_RecordStream

PaStream* LA_RecordStream = nullptr

static

Active recording stream

Definition at line 42 of file liveio.c.

Data Structures

Functions

Variables

Detailed Description

Function Documentation

◆ _ContinuousRecordCallback()

◆ _ensure_init()

◆ _PlayCallback()

◆ _PlayStreamFinished()

◆ _RecordCallback()

◆ _RecordStreamFinished()

◆ _setup_input_params()

◆ _setup_output_params()

◆ LA_get_cur_play_time()

◆ LA_get_cur_record_time()

◆ LA_init()

◆ LA_is_playing()

◆ LA_is_recording()

◆ LA_play()

◆ LA_play_callback()

◆ LA_print_last_error()

◆ LA_record()

◆ LA_record_callback()

◆ LA_stop_playing()

◆ LA_stop_recording()

◆ LA_terminate()

Variable Documentation

◆ LA_data

◆ LA_InitDone

◆ LA_LastError

◆ LA_PlayStream

◆ LA_RecordStream