1/* Copyright (C) Jean-Marc Valin */
2/**
3   @file speex_echo.h
4   @brief Echo cancellation
5*/
6/*
7   Redistribution and use in source and binary forms, with or without
8   modification, are permitted provided that the following conditions are
9   met:
10
11   1. Redistributions of source code must retain the above copyright notice,
12   this list of conditions and the following disclaimer.
13
14   2. Redistributions in binary form must reproduce the above copyright
15   notice, this list of conditions and the following disclaimer in the
16   documentation and/or other materials provided with the distribution.
17
18   3. The name of the author may not be used to endorse or promote products
19   derived from this software without specific prior written permission.
20
21   THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
22   IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
23   OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
24   DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
25   INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
26   (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
27   SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28   HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
29   STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
30   ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
31   POSSIBILITY OF SUCH DAMAGE.
32*/
33
34#ifndef SPEEX_ECHO_H
35#define SPEEX_ECHO_H
36/** @defgroup SpeexEchoState SpeexEchoState: Acoustic echo canceller
37 *  This is the acoustic echo canceller module.
38 *  @{
39 */
40#include "speex/speex_types.h"
41
42#ifdef __cplusplus
43extern "C" {
44#endif
45
46/** Obtain frame size used by the AEC */
47#define SPEEX_ECHO_GET_FRAME_SIZE 3
48
49/** Set sampling rate */
50#define SPEEX_ECHO_SET_SAMPLING_RATE 24
51/** Get sampling rate */
52#define SPEEX_ECHO_GET_SAMPLING_RATE 25
53
54/* Can't set window sizes */
55/** Get size of impulse response (int32) */
56#define SPEEX_ECHO_GET_IMPULSE_RESPONSE_SIZE 27
57
58/* Can't set window content */
59/** Get impulse response (int32[]) */
60#define SPEEX_ECHO_GET_IMPULSE_RESPONSE 29
61
62/** Internal echo canceller state. Should never be accessed directly. */
63struct SpeexEchoState_;
64
65/** @class SpeexEchoState
66 * This holds the state of the echo canceller. You need one per channel.
67*/
68
69/** Internal echo canceller state. Should never be accessed directly. */
70typedef struct SpeexEchoState_ SpeexEchoState;
71
72/** Creates a new echo canceller state
73 * @param frame_size Number of samples to process at one time (should correspond to 10-20 ms)
74 * @param filter_length Number of samples of echo to cancel (should generally correspond to 100-500 ms)
75 * @return Newly-created echo canceller state
76 */
77SpeexEchoState *speex_echo_state_init(int frame_size, int filter_length);
78
79/** Creates a new multi-channel echo canceller state
80 * @param frame_size Number of samples to process at one time (should correspond to 10-20 ms)
81 * @param filter_length Number of samples of echo to cancel (should generally correspond to 100-500 ms)
82 * @param nb_mic Number of microphone channels
83 * @param nb_speakers Number of speaker channels
84 * @return Newly-created echo canceller state
85 */
86SpeexEchoState *speex_echo_state_init_mc(int frame_size, int filter_length, int nb_mic, int nb_speakers);
87
88/** Destroys an echo canceller state
89 * @param st Echo canceller state
90*/
91void speex_echo_state_destroy(SpeexEchoState *st);
92
93/** Performs echo cancellation a frame, based on the audio sent to the speaker (no delay is added
94 * to playback in this form)
95 *
96 * @param st Echo canceller state
97 * @param rec Signal from the microphone (near end + far end echo)
98 * @param play Signal played to the speaker (received from far end)
99 * @param out Returns near-end signal with echo removed
100 */
101void speex_echo_cancellation(SpeexEchoState *st, const spx_int16_t *rec, const spx_int16_t *play, spx_int16_t *out);
102
103/** Performs echo cancellation a frame (deprecated) */
104void speex_echo_cancel(SpeexEchoState *st, const spx_int16_t *rec, const spx_int16_t *play, spx_int16_t *out, spx_int32_t *Yout);
105
106/** Perform echo cancellation using internal playback buffer, which is delayed by two frames
107 * to account for the delay introduced by most soundcards (but it could be off!)
108 * @param st Echo canceller state
109 * @param rec Signal from the microphone (near end + far end echo)
110 * @param out Returns near-end signal with echo removed
111*/
112void speex_echo_capture(SpeexEchoState *st, const spx_int16_t *rec, spx_int16_t *out);
113
114/** Let the echo canceller know that a frame was just queued to the soundcard
115 * @param st Echo canceller state
116 * @param play Signal played to the speaker (received from far end)
117*/
118void speex_echo_playback(SpeexEchoState *st, const spx_int16_t *play);
119
120/** Reset the echo canceller to its original state
121 * @param st Echo canceller state
122 */
123void speex_echo_state_reset(SpeexEchoState *st);
124
125/** Used like the ioctl function to control the echo canceller parameters
126 *
127 * @param st Echo canceller state
128 * @param request ioctl-type request (one of the SPEEX_ECHO_* macros)
129 * @param ptr Data exchanged to-from function
130 * @return 0 if no error, -1 if request in unknown
131 */
132int speex_echo_ctl(SpeexEchoState *st, int request, void *ptr);
133
134
135
136struct SpeexDecorrState_;
137
138typedef struct SpeexDecorrState_ SpeexDecorrState;
139
140
141/** Create a state for the channel decorrelation algorithm
142    This is useful for multi-channel echo cancellation only
143 * @param rate Sampling rate
144 * @param channels Number of channels (it's a bit pointless if you don't have at least 2)
145 * @param frame_size Size of the frame to process at ones (counting samples *per* channel)
146*/
147SpeexDecorrState *speex_decorrelate_new(int rate, int channels, int frame_size);
148
149/** Remove correlation between the channels by modifying the phase and possibly
150    adding noise in a way that is not (or little) perceptible.
151 * @param st Decorrelator state
152 * @param in Input audio in interleaved format
153 * @param out Result of the decorrelation (out *may* alias in)
154 * @param strength How much alteration of the audio to apply from 0 to 100.
155*/
156void speex_decorrelate(SpeexDecorrState *st, const spx_int16_t *in, spx_int16_t *out, int strength);
157
158/** Destroy a Decorrelation state
159 * @param st State to destroy
160*/
161void speex_decorrelate_destroy(SpeexDecorrState *st);
162
163
164#ifdef __cplusplus
165}
166#endif
167
168
169/** @}*/
170#endif
171