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 "speexdsp_types.h" 41 42 #ifdef __cplusplus 43 extern "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. */ 63 struct 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. */ 70 typedef 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 */ 77 SpeexEchoState *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 */ 86 SpeexEchoState *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 */ 91 void 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 */ 101 void 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) */ 104 void 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 */ 112 void 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 */ 118 void 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 */ 123 void 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 */ 132 int speex_echo_ctl(SpeexEchoState *st, int request, void *ptr); 133 134 135 136 struct SpeexDecorrState_; 137 138 typedef 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 */ 147 SpeexDecorrState *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 */ 156 void 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 */ 161 void speex_decorrelate_destroy(SpeexDecorrState *st); 162 163 164 #ifdef __cplusplus 165 } 166 #endif 167 168 169 /** @}*/ 170 #endif 171