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 1.25 2009/02/10 13:06:47 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 typedef struct g722_encode_state_s g722_encode_state_t; 00060 00061 typedef struct g722_decode_state_s g722_decode_state_t; 00062 00063 #if defined(__cplusplus) 00064 extern "C" 00065 { 00066 #endif 00067 00068 /*! Initialise an G.722 encode context. 00069 \param s The G.722 encode context. 00070 \param rate The required bit rate for the G.722 data. 00071 The valid rates are 64000, 56000 and 48000. 00072 \param options 00073 \return A pointer to the G.722 encode context, or NULL for error. */ 00074 SPAN_DECLARE(g722_encode_state_t *) g722_encode_init(g722_encode_state_t *s, int rate, int options); 00075 00076 SPAN_DECLARE(int) g722_encode_release(g722_encode_state_t *s); 00077 00078 SPAN_DECLARE(int) g722_encode_free(g722_encode_state_t *s); 00079 00080 /*! Encode a buffer of linear PCM data to G.722 00081 \param s The G.722 context. 00082 \param g722_data The G.722 data produced. 00083 \param amp The audio sample buffer. 00084 \param len The number of samples in the buffer. 00085 \return The number of bytes of G.722 data produced. */ 00086 SPAN_DECLARE(int) g722_encode(g722_encode_state_t *s, uint8_t g722_data[], const int16_t amp[], int len); 00087 00088 /*! Initialise an G.722 decode context. 00089 \param s The G.722 decode context. 00090 \param rate The bit rate of the G.722 data. 00091 The valid rates are 64000, 56000 and 48000. 00092 \param options 00093 \return A pointer to the G.722 decode context, or NULL for error. */ 00094 SPAN_DECLARE(g722_decode_state_t *) g722_decode_init(g722_decode_state_t *s, int rate, int options); 00095 00096 SPAN_DECLARE(int) g722_decode_release(g722_decode_state_t *s); 00097 00098 SPAN_DECLARE(int) g722_decode_free(g722_decode_state_t *s); 00099 00100 /*! Decode a buffer of G.722 data to linear PCM. 00101 \param s The G.722 context. 00102 \param amp The audio sample buffer. 00103 \param g722_data 00104 \param len 00105 \return The number of samples returned. */ 00106 SPAN_DECLARE(int) g722_decode(g722_decode_state_t *s, int16_t amp[], const uint8_t g722_data[], int len); 00107 00108 #if defined(__cplusplus) 00109 } 00110 #endif 00111 00112 #endif