liveio.h File Reference

Live audio recording and playback via PortAudio. More...

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <portaudio.h>

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Typedefs
typedef int	LaError_t
	Return type for live audio functions.

Enumerations
enum	LA_ERRORCODE { LA_OK = 0 , LA_ERROR = 1 }
	Error codes returned by live audio functions. More...
enum	LA_RECORDTYPE { LA_REC_ONCE = 0 , LA_REC_CONT }
	Recording modes for LA_record(). More...

Functions
LaError_t	LA_init (void)
	Initialise the PortAudio system.
LaError_t	LA_terminate (void)
	Shut down the PortAudio system.
void	LA_print_last_error (FILE *stream)
	Print the last PortAudio error message to the given stream.
int	LA_is_recording (void)
	Check if the recording stream is active.
double	LA_get_cur_record_time (void)
	Get the current time (in seconds) of the recording stream.
void	LA_stop_recording (void)
	Stop the current recording.
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_record_callback (unsigned samprate, PaStreamCallback *cb, void *cb_data)
	Record using a user-supplied PortAudio callback function.
int	LA_is_playing (void)
	Check if the playback stream is active.
double	LA_get_cur_play_time (void)
	Get the current time (in seconds) of the playback stream.
void	LA_stop_playing (void)
	Stop the current playback.
LaError_t	LA_play (const void *buffer, unsigned long bufsize, unsigned samprate)
	Play audio from a buffer to the default output device.
LaError_t	LA_play_callback (unsigned samprate, PaStreamCallback *cb, void *cb_data)
	Play using a user-supplied PortAudio callback function.

Detailed Description

Live audio recording and playback via PortAudio.

This module wraps the PortAudio library to provide simple functions for recording from a microphone and playing back to speakers. All functions are non-blocking – they return immediately while audio I/O happens in the background via callbacks.

Typical usage:

1. Call LA_init() to initialise the audio system.
2. Call LA_record() to start recording into a buffer.
3. Poll LA_is_recording() until recording finishes.
4. Call LA_play() to play back the recorded audio.
5. Call LA_terminate() when done.

Definition in file liveio.h.

Typedef Documentation

LaError_t

typedef int LaError_t

Return type for live audio functions.

Definition at line 27 of file liveio.h.

Enumeration Type Documentation

LA_ERRORCODE

enum LA_ERRORCODE

Error codes returned by live audio functions.

Enumerator
LA_OK	Operation succeeded.
LA_ERROR	Something went wrong.

Definition at line 30 of file liveio.h.

LA_RECORDTYPE

enum LA_RECORDTYPE

Recording modes for LA_record().

Enumerator
LA_REC_ONCE	Record until the buffer is full, then stop.
LA_REC_CONT	Record continuously in a circular buffer.

Definition at line 36 of file liveio.h.

Function Documentation

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.

Must be called before any other LA_ function.

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 active.

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

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 active.

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

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

)

Shut down the PortAudio system.

Call when you are finished with audio.

Shut down the PortAudio system.

Returns

LA_OK on success, LA_ERROR on failure.

Definition at line 441 of file liveio.c.