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/* $Id$ */
/*
* Copyright (C) 2003-2007 Benny Prijono <benny@prijono.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifndef __PJMEDIA_ECHO_H__
#define __PJMEDIA_ECHO_H__
/**
* @file echo.h
* @brief Echo Cancellation API.
*/
#include <pjmedia/types.h>
/**
* @defgroup PJMEDIA_Echo_Cancel Accoustic Echo Cancellation API
* @ingroup PJMEDIA_PORT
* @brief Echo Cancellation API.
* @{
*
* This section describes API to perform echo cancellation to audio signal.
* There may be multiple echo canceller implementation in PJMEDIA, ranging
* from simple echo suppressor to a full Accoustic Echo Canceller/AEC. By
* using this API, application should be able to use which EC backend to
* use base on the requirement and capability of the platform.
*/
PJ_BEGIN_DECL
/**
* Opaque type for PJMEDIA Echo Canceller state.
*/
typedef struct pjmedia_echo_state pjmedia_echo_state;
/**
* Echo cancellation options.
*/
typedef enum pjmedia_echo_flag
{
/**
* If PJMEDIA_ECHO_SIMPLE flag is specified during echo canceller
* creation, then a simple echo suppressor will be used instead of
* an accoustic echo cancellation.
*/
PJMEDIA_ECHO_SIMPLE = 1,
/**
* If PJMEDIA_ECHO_NO_LOCK flag is specified, no mutex will be created
* for the echo canceller, but application will guarantee that echo
* canceller will not be called by different threads at the same time.
*/
PJMEDIA_ECHO_NO_LOCK = 2
} pjmedia_echo_flag;
/**
* Create the echo canceller.
*
* @param pool Pool to allocate memory.
* @param clock_rate Media clock rate/sampling rate.
* @param samples_per_frame Number of samples per frame.
* @param tail_ms Tail length, miliseconds.
* @param latency_ms Total lacency introduced by playback and
* recording device. Set to zero if the latency
* is not known.
* @param options Options. If PJMEDIA_ECHO_SIMPLE is specified,
* then a simple echo suppressor implementation
* will be used instead of an accoustic echo
* cancellation.
* See #pjmedia_echo_flag for other options.
* @param p_echo Pointer to receive the Echo Canceller state.
*
* @return PJ_SUCCESS on success, or the appropriate status.
*/
PJ_DECL(pj_status_t) pjmedia_echo_create(pj_pool_t *pool,
unsigned clock_rate,
unsigned samples_per_frame,
unsigned tail_ms,
unsigned latency_ms,
unsigned options,
pjmedia_echo_state **p_echo );
/**
* Destroy the Echo Canceller.
*
* @param echo The Echo Canceller.
*
* @return PJ_SUCCESS on success.
*/
PJ_DECL(pj_status_t) pjmedia_echo_destroy(pjmedia_echo_state *echo );
/**
* Let the Echo Canceller knows that a frame has been played to the speaker.
* The Echo Canceller will keep the frame in its internal buffer, to be used
* when cancelling the echo with #pjmedia_echo_capture().
*
* @param echo The Echo Canceller.
* @param play_frm Sample buffer containing frame to be played
* (or has been played) to the playback device.
* The frame must contain exactly samples_per_frame
* number of samples.
*
* @return PJ_SUCCESS on success.
*/
PJ_DECL(pj_status_t) pjmedia_echo_playback(pjmedia_echo_state *echo,
pj_int16_t *play_frm );
/**
* Let the Echo Canceller knows that a frame has been captured from
* the microphone.
* The Echo Canceller will cancel the echo from the captured signal,
* using the internal buffer (supplied by #pjmedia_echo_playback())
* as the FES (Far End Speech) reference.
*
* @param echo The Echo Canceller.
* @param rec_frm On input, it contains the input signal (captured
* from microphone) which echo is to be removed.
* Upon returning this function, this buffer contain
* the processed signal with the echo removed.
* The frame must contain exactly samples_per_frame
* number of samples.
* @param options Echo cancellation options, reserved for future use.
* Put zero for now.
*
* @return PJ_SUCCESS on success.
*/
PJ_DECL(pj_status_t) pjmedia_echo_capture(pjmedia_echo_state *echo,
pj_int16_t *rec_frm,
unsigned options );
/**
* Perform echo cancellation.
*
* @param echo The Echo Canceller.
* @param rec_frm On input, it contains the input signal (captured
* from microphone) which echo is to be removed.
* Upon returning this function, this buffer contain
* the processed signal with the echo removed.
* @param play_frm Sample buffer containing frame to be played
* (or has been played) to the playback device.
* The frame must contain exactly samples_per_frame
* number of samples.
* @param options Echo cancellation options, reserved for future use.
* Put zero for now.
* @param reserved Reserved for future use, put NULL for now.
*
* @return PJ_SUCCESS on success.
*/
PJ_DECL(pj_status_t) pjmedia_echo_cancel( pjmedia_echo_state *echo,
pj_int16_t *rec_frm,
const pj_int16_t *play_frm,
unsigned options,
void *reserved );
PJ_END_DECL
/**
* @}
*/
#endif /* __PJMEDIA_ECHO_H__ */
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