00001 /* 00002 * SpanDSP - a series of DSP components for telephony 00003 * 00004 * g722.h - The ITU G.722 codec. 00005 * 00006 * Written by Steve Underwood <steveu@coppice.org> 00007 * 00008 * Copyright (C) 2005 Steve Underwood 00009 * 00010 * All rights reserved. 00011 * 00012 * This program is free software; you can redistribute it and/or modify 00013 * it under the terms of the GNU Lesser General Public License version 2.1, 00014 * as published by the Free Software Foundation. 00015 * 00016 * This program is distributed in the hope that it will be useful, 00017 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00018 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00019 * GNU Lesser General Public License for more details. 00020 * 00021 * You should have received a copy of the GNU Lesser General Public 00022 * License along with this program; if not, write to the Free Software 00023 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 00024 * 00025 * Based on a single channel G.722 codec which is: 00026 * 00027 ***** Copyright (c) CMU 1993 ***** 00028 * Computer Science, Speech Group 00029 * Chengxiang Lu and Alex Hauptmann 00030 * 00031 * $Id: g722.h,v 1.26 2009/04/12 09:12:10 steveu Exp $ 00032 */ 00033 00034 00035 /*! \file */ 00036 00037 #if !defined(_SPANDSP_G722_H_) 00038 #define _SPANDSP_G722_H_ 00039 00040 /*! \page g722_page G.722 encoding and decoding 00041 \section g722_page_sec_1 What does it do? 00042 The G.722 module is a bit exact implementation of the ITU G.722 specification for all three 00043 specified bit rates - 64000bps, 56000bps and 48000bps. It passes the ITU tests. 00044 00045 To allow fast and flexible interworking with narrow band telephony, the encoder and decoder 00046 support an option for the linear audio to be an 8k samples/second stream. In this mode the 00047 codec is considerably faster, and still fully compatible with wideband terminals using G.722. 00048 00049 \section g722_page_sec_2 How does it work? 00050 ???. 00051 */ 00052 00053 enum 00054 { 00055 G722_SAMPLE_RATE_8000 = 0x0001, 00056 G722_PACKED = 0x0002 00057 }; 00058 00059 /*! 00060 G.722 encode state 00061 */ 00062 typedef struct g722_encode_state_s g722_encode_state_t; 00063 00064 /*! 00065 G.722 decode state 00066 */ 00067 typedef struct g722_decode_state_s g722_decode_state_t; 00068 00069 #if defined(__cplusplus) 00070 extern "C" 00071 { 00072 #endif 00073 00074 /*! Initialise an G.722 encode context. 00075 \param s The G.722 encode context. 00076 \param rate The required bit rate for the G.722 data. 00077 The valid rates are 64000, 56000 and 48000. 00078 \param options 00079 \return A pointer to the G.722 encode context, or NULL for error. */ 00080 SPAN_DECLARE(g722_encode_state_t *) g722_encode_init(g722_encode_state_t *s, int rate, int options); 00081 00082 /*! Release a G.722 encode context. 00083 \param s The G.722 encode context. 00084 \return 0 for OK. */ 00085 SPAN_DECLARE(int) g722_encode_release(g722_encode_state_t *s); 00086 00087 /*! Free a G.722 encode context. 00088 \param s The G.722 encode context. 00089 \return 0 for OK. */ 00090 SPAN_DECLARE(int) g722_encode_free(g722_encode_state_t *s); 00091 00092 /*! Encode a buffer of linear PCM data to G.722 00093 \param s The G.722 context. 00094 \param g722_data The G.722 data produced. 00095 \param amp The audio sample buffer. 00096 \param len The number of samples in the buffer. 00097 \return The number of bytes of G.722 data produced. */ 00098 SPAN_DECLARE(int) g722_encode(g722_encode_state_t *s, uint8_t g722_data[], const int16_t amp[], int len); 00099 00100 /*! Initialise an G.722 decode context. 00101 \param s The G.722 decode context. 00102 \param rate The bit rate of the G.722 data. 00103 The valid rates are 64000, 56000 and 48000. 00104 \param options 00105 \return A pointer to the G.722 decode context, or NULL for error. */ 00106 SPAN_DECLARE(g722_decode_state_t *) g722_decode_init(g722_decode_state_t *s, int rate, int options); 00107 00108 /*! Release a G.722 decode context. 00109 \param s The G.722 decode context. 00110 \return 0 for OK. */ 00111 SPAN_DECLARE(int) g722_decode_release(g722_decode_state_t *s); 00112 00113 /*! Free a G.722 decode context. 00114 \param s The G.722 decode context. 00115 \return 0 for OK. */ 00116 SPAN_DECLARE(int) g722_decode_free(g722_decode_state_t *s); 00117 00118 /*! Decode a buffer of G.722 data to linear PCM. 00119 \param s The G.722 context. 00120 \param amp The audio sample buffer. 00121 \param g722_data 00122 \param len 00123 \return The number of samples returned. */ 00124 SPAN_DECLARE(int) g722_decode(g722_decode_state_t *s, int16_t amp[], const uint8_t g722_data[], int len); 00125 00126 #if defined(__cplusplus) 00127 } 00128 #endif 00129 00130 #endif