1 /* 2 * OSLEC - A line echo canceller. This code is being developed 3 * against and partially complies with G168. Using code from SpanDSP 4 * 5 * Written by Steve Underwood <steveu@coppice.org> 6 * and David Rowe <david_at_rowetel_dot_com> 7 * 8 * Copyright (C) 2001 Steve Underwood and 2007-2008 David Rowe 9 * 10 * All rights reserved. 11 * 12 * This program is free software; you can redistribute it and/or modify 13 * it under the terms of the GNU General Public License version 2, as 14 * published by the Free Software Foundation. 15 * 16 * This program is distributed in the hope that it will be useful, 17 * but WITHOUT ANY WARRANTY; without even the implied warranty of 18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 19 * GNU General Public License for more details. 20 * 21 * You should have received a copy of the GNU General Public License 22 * along with this program; if not, write to the Free Software 23 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 24 * 25 */ 26 27 #ifndef __OSLEC_H 28 #define __OSLEC_H 29 30 /* Mask bits for the adaption mode */ 31 #define ECHO_CAN_USE_ADAPTION 0x01 32 #define ECHO_CAN_USE_NLP 0x02 33 #define ECHO_CAN_USE_CNG 0x04 34 #define ECHO_CAN_USE_CLIP 0x08 35 #define ECHO_CAN_USE_TX_HPF 0x10 36 #define ECHO_CAN_USE_RX_HPF 0x20 37 #define ECHO_CAN_DISABLE 0x40 38 39 /** 40 * oslec_state: G.168 echo canceller descriptor. 41 * 42 * This defines the working state for a line echo canceller. 43 */ 44 struct oslec_state; 45 46 /** 47 * oslec_create - Create a voice echo canceller context. 48 * @len: The length of the canceller, in samples. 49 * @return: The new canceller context, or NULL if the canceller could not be 50 * created. 51 */ 52 struct oslec_state *oslec_create(int len, int adaption_mode); 53 54 /** 55 * oslec_free - Free a voice echo canceller context. 56 * @ec: The echo canceller context. 57 */ 58 void oslec_free(struct oslec_state *ec); 59 60 /** 61 * oslec_flush - Flush (reinitialise) a voice echo canceller context. 62 * @ec: The echo canceller context. 63 */ 64 void oslec_flush(struct oslec_state *ec); 65 66 /** 67 * oslec_adaption_mode - set the adaption mode of a voice echo canceller context. 68 * @ec The echo canceller context. 69 * @adaption_mode: The mode. 70 */ 71 void oslec_adaption_mode(struct oslec_state *ec, int adaption_mode); 72 73 void oslec_snapshot(struct oslec_state *ec); 74 75 /** 76 * oslec_update: Process a sample through a voice echo canceller. 77 * @ec: The echo canceller context. 78 * @tx: The transmitted audio sample. 79 * @rx: The received audio sample. 80 * 81 * The return value is the clean (echo cancelled) received sample. 82 */ 83 int16_t oslec_update(struct oslec_state *ec, int16_t tx, int16_t rx); 84 85 /** 86 * oslec_hpf_tx: Process to high pass filter the tx signal. 87 * @ec: The echo canceller context. 88 * @tx: The transmitted auio sample. 89 * 90 * The return value is the HP filtered transmit sample, send this to your D/A. 91 */ 92 int16_t oslec_hpf_tx(struct oslec_state *ec, int16_t tx); 93 94 #endif /* __OSLEC_H */ 95