Use the libspeexdsp resampler
AFAICT it runs a little slower? but it's fixed point, and has much better understood audio characteristics.
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jacqueline
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/* Copyright (C) Jean-Marc Valin */
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/**
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@file speex_echo.h
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@brief Echo cancellation
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*/
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/*
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are
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met:
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1. Redistributions of source code must retain the above copyright notice,
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this list of conditions and the following disclaimer.
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2. Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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3. The name of the author may not be used to endorse or promote products
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derived from this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
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INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef SPEEX_ECHO_H
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#define SPEEX_ECHO_H
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/** @defgroup SpeexEchoState SpeexEchoState: Acoustic echo canceller
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* This is the acoustic echo canceller module.
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* @{
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*/
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#include "speexdsp_types.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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/** Obtain frame size used by the AEC */
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#define SPEEX_ECHO_GET_FRAME_SIZE 3
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/** Set sampling rate */
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#define SPEEX_ECHO_SET_SAMPLING_RATE 24
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/** Get sampling rate */
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#define SPEEX_ECHO_GET_SAMPLING_RATE 25
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/* Can't set window sizes */
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/** Get size of impulse response (int32) */
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#define SPEEX_ECHO_GET_IMPULSE_RESPONSE_SIZE 27
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/* Can't set window content */
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/** Get impulse response (int32[]) */
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#define SPEEX_ECHO_GET_IMPULSE_RESPONSE 29
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/** Internal echo canceller state. Should never be accessed directly. */
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struct SpeexEchoState_;
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/** @class SpeexEchoState
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* This holds the state of the echo canceller. You need one per channel.
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*/
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/** Internal echo canceller state. Should never be accessed directly. */
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typedef struct SpeexEchoState_ SpeexEchoState;
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/** Creates a new echo canceller state
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* @param frame_size Number of samples to process at one time (should correspond to 10-20 ms)
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* @param filter_length Number of samples of echo to cancel (should generally correspond to 100-500 ms)
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* @return Newly-created echo canceller state
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*/
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SpeexEchoState *speex_echo_state_init(int frame_size, int filter_length);
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/** Creates a new multi-channel echo canceller state
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* @param frame_size Number of samples to process at one time (should correspond to 10-20 ms)
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* @param filter_length Number of samples of echo to cancel (should generally correspond to 100-500 ms)
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* @param nb_mic Number of microphone channels
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* @param nb_speakers Number of speaker channels
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* @return Newly-created echo canceller state
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*/
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SpeexEchoState *speex_echo_state_init_mc(int frame_size, int filter_length, int nb_mic, int nb_speakers);
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/** Destroys an echo canceller state
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* @param st Echo canceller state
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*/
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void speex_echo_state_destroy(SpeexEchoState *st);
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/** Performs echo cancellation a frame, based on the audio sent to the speaker (no delay is added
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* to playback in this form)
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*
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* @param st Echo canceller state
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* @param rec Signal from the microphone (near end + far end echo)
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* @param play Signal played to the speaker (received from far end)
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* @param out Returns near-end signal with echo removed
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*/
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void speex_echo_cancellation(SpeexEchoState *st, const spx_int16_t *rec, const spx_int16_t *play, spx_int16_t *out);
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/** Performs echo cancellation a frame (deprecated) */
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void speex_echo_cancel(SpeexEchoState *st, const spx_int16_t *rec, const spx_int16_t *play, spx_int16_t *out, spx_int32_t *Yout);
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/** Perform echo cancellation using internal playback buffer, which is delayed by two frames
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* to account for the delay introduced by most soundcards (but it could be off!)
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* @param st Echo canceller state
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* @param rec Signal from the microphone (near end + far end echo)
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* @param out Returns near-end signal with echo removed
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*/
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void speex_echo_capture(SpeexEchoState *st, const spx_int16_t *rec, spx_int16_t *out);
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/** Let the echo canceller know that a frame was just queued to the soundcard
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* @param st Echo canceller state
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* @param play Signal played to the speaker (received from far end)
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*/
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void speex_echo_playback(SpeexEchoState *st, const spx_int16_t *play);
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/** Reset the echo canceller to its original state
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* @param st Echo canceller state
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*/
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void speex_echo_state_reset(SpeexEchoState *st);
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/** Used like the ioctl function to control the echo canceller parameters
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*
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* @param st Echo canceller state
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* @param request ioctl-type request (one of the SPEEX_ECHO_* macros)
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* @param ptr Data exchanged to-from function
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* @return 0 if no error, -1 if request in unknown
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*/
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int speex_echo_ctl(SpeexEchoState *st, int request, void *ptr);
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struct SpeexDecorrState_;
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typedef struct SpeexDecorrState_ SpeexDecorrState;
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/** Create a state for the channel decorrelation algorithm
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This is useful for multi-channel echo cancellation only
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* @param rate Sampling rate
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* @param channels Number of channels (it's a bit pointless if you don't have at least 2)
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* @param frame_size Size of the frame to process at ones (counting samples *per* channel)
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*/
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SpeexDecorrState *speex_decorrelate_new(int rate, int channels, int frame_size);
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/** Remove correlation between the channels by modifying the phase and possibly
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adding noise in a way that is not (or little) perceptible.
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* @param st Decorrelator state
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* @param in Input audio in interleaved format
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* @param out Result of the decorrelation (out *may* alias in)
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* @param strength How much alteration of the audio to apply from 0 to 100.
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*/
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void speex_decorrelate(SpeexDecorrState *st, const spx_int16_t *in, spx_int16_t *out, int strength);
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/** Destroy a Decorrelation state
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* @param st State to destroy
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*/
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void speex_decorrelate_destroy(SpeexDecorrState *st);
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#ifdef __cplusplus
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}
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#endif
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/** @}*/
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#endif
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