spandsp 0.0.6
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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 00032 00033 /*! \file */ 00034 00035 #if !defined(_SPANDSP_G722_H_) 00036 #define _SPANDSP_G722_H_ 00037 00038 /*! \page g722_page G.722 encoding and decoding 00039 \section g722_page_sec_1 What does it do? 00040 The G.722 module is a bit exact implementation of the ITU G.722 specification for all three 00041 specified bit rates - 64000bps, 56000bps and 48000bps. It passes the ITU tests. 00042 00043 To allow fast and flexible interworking with narrow band telephony, the encoder and decoder 00044 support an option for the linear audio to be an 8k samples/second stream. In this mode the 00045 codec is considerably faster, and still fully compatible with wideband terminals using G.722. 00046 00047 \section g722_page_sec_2 How does it work? 00048 ???. 00049 */ 00050 00051 enum 00052 { 00053 G722_SAMPLE_RATE_8000 = 0x0001, 00054 G722_PACKED = 0x0002 00055 }; 00056 00057 /*! 00058 G.722 encode state 00059 */ 00060 typedef struct g722_encode_state_s g722_encode_state_t; 00061 00062 /*! 00063 G.722 decode state 00064 */ 00065 typedef struct g722_decode_state_s g722_decode_state_t; 00066 00067 #if defined(__cplusplus) 00068 extern "C" 00069 { 00070 #endif 00071 00072 /*! Initialise an G.722 encode context. 00073 \param s The G.722 encode context. 00074 \param rate The required bit rate for the G.722 data. 00075 The valid rates are 64000, 56000 and 48000. 00076 \param options 00077 \return A pointer to the G.722 encode context, or NULL for error. */ 00078 SPAN_DECLARE(g722_encode_state_t *) g722_encode_init(g722_encode_state_t *s, int rate, int options); 00079 00080 /*! Release a G.722 encode context. 00081 \param s The G.722 encode context. 00082 \return 0 for OK. */ 00083 SPAN_DECLARE(int) g722_encode_release(g722_encode_state_t *s); 00084 00085 /*! Free a G.722 encode context. 00086 \param s The G.722 encode context. 00087 \return 0 for OK. */ 00088 SPAN_DECLARE(int) g722_encode_free(g722_encode_state_t *s); 00089 00090 /*! Encode a buffer of linear PCM data to G.722 00091 \param s The G.722 context. 00092 \param g722_data The G.722 data produced. 00093 \param amp The audio sample buffer. 00094 \param len The number of samples in the buffer. 00095 \return The number of bytes of G.722 data produced. */ 00096 SPAN_DECLARE(int) g722_encode(g722_encode_state_t *s, uint8_t g722_data[], const int16_t amp[], int len); 00097 00098 /*! Initialise an G.722 decode context. 00099 \param s The G.722 decode context. 00100 \param rate The bit rate of the G.722 data. 00101 The valid rates are 64000, 56000 and 48000. 00102 \param options 00103 \return A pointer to the G.722 decode context, or NULL for error. */ 00104 SPAN_DECLARE(g722_decode_state_t *) g722_decode_init(g722_decode_state_t *s, int rate, int options); 00105 00106 /*! Release a G.722 decode context. 00107 \param s The G.722 decode context. 00108 \return 0 for OK. */ 00109 SPAN_DECLARE(int) g722_decode_release(g722_decode_state_t *s); 00110 00111 /*! Free a G.722 decode context. 00112 \param s The G.722 decode context. 00113 \return 0 for OK. */ 00114 SPAN_DECLARE(int) g722_decode_free(g722_decode_state_t *s); 00115 00116 /*! Decode a buffer of G.722 data to linear PCM. 00117 \param s The G.722 context. 00118 \param amp The audio sample buffer. 00119 \param g722_data 00120 \param len 00121 \return The number of samples returned. */ 00122 SPAN_DECLARE(int) g722_decode(g722_decode_state_t *s, int16_t amp[], const uint8_t g722_data[], int len); 00123 00124 #if defined(__cplusplus) 00125 } 00126 #endif 00127 00128 #endif