g722.h

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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 General Public License version 2, or
00014  * the Lesser GNU General Public License version 2.1, as published by
00015  * the Free Software Foundation.
00016  *
00017  * This program is distributed in the hope that it will be useful,
00018  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00019  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00020  * GNU General Public License for more details.
00021  *
00022  * You should have received a copy of the GNU General Public License
00023  * along with this program; if not, write to the Free Software
00024  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
00025  *
00026  * Based on a single channel G.722 codec which is:
00027  *
00028  *****    Copyright (c) CMU    1993      *****
00029  * Computer Science, Speech Group
00030  * Chengxiang Lu and Alex Hauptmann
00031  *
00032  * $Id: g722.h,v 1.17 2008/02/09 15:32:26 steveu Exp $
00033  */
00034 
00035 
00036 /*! \file */
00037 
00038 #if !defined(_SPANDSP_G722_H_)
00039 #define _SPANDSP_G722_H_
00040 
00041 /*! \page g722_page G.722 encoding and decoding
00042 \section g722_page_sec_1 What does it do?
00043 The G.722 module is a bit exact implementation of the ITU G.722 specification for all three
00044 specified bit rates - 64000bps, 56000bps and 48000bps. It passes the ITU tests.
00045 
00046 To allow fast and flexible interworking with narrow band telephony, the encoder and decoder
00047 support an option for the linear audio to be an 8k samples/second stream. In this mode the
00048 codec is considerably faster, and still fully compatible with wideband terminals using G.722.
00049 
00050 \section g722_page_sec_2 How does it work?
00051 ???.
00052 */
00053 
00054 enum
00055 {
00056     G722_SAMPLE_RATE_8000 = 0x0001,
00057     G722_PACKED = 0x0002
00058 };
00059 
00060 typedef struct
00061 {
00062     /*! TRUE if the operating in the special ITU test mode, with the band split filters
00063              disabled. */
00064     int itu_test_mode;
00065     /*! TRUE if the G.722 data is packed */
00066     int packed;
00067     /*! TRUE if encode from 8k samples/second */
00068     int eight_k;
00069     /*! 6 for 48000kbps, 7 for 56000kbps, or 8 for 64000kbps. */
00070     int bits_per_sample;
00071 
00072     /*! Signal history for the QMF */
00073     int x[24];
00074 
00075     struct
00076     {
00077         int s;
00078         int sp;
00079         int sz;
00080         int r[3];
00081         int a[3];
00082         int ap[3];
00083         int p[3];
00084         int d[7];
00085         int b[7];
00086         int bp[7];
00087         int sg[7];
00088         int nb;
00089         int det;
00090     } band[2];
00091 
00092     unsigned int in_buffer;
00093     int in_bits;
00094     unsigned int out_buffer;
00095     int out_bits;
00096 } g722_encode_state_t;
00097 
00098 typedef struct
00099 {
00100     /*! TRUE if the operating in the special ITU test mode, with the band split filters
00101              disabled. */
00102     int itu_test_mode;
00103     /*! TRUE if the G.722 data is packed */
00104     int packed;
00105     /*! TRUE if decode to 8k samples/second */
00106     int eight_k;
00107     /*! 6 for 48000kbps, 7 for 56000kbps, or 8 for 64000kbps. */
00108     int bits_per_sample;
00109 
00110     /*! Signal history for the QMF */
00111     int x[24];
00112 
00113     struct
00114     {
00115         int s;
00116         int sp;
00117         int sz;
00118         int r[3];
00119         int a[3];
00120         int ap[3];
00121         int p[3];
00122         int d[7];
00123         int b[7];
00124         int bp[7];
00125         int sg[7];
00126         int nb;
00127         int det;
00128     } band[2];
00129     
00130     unsigned int in_buffer;
00131     int in_bits;
00132     unsigned int out_buffer;
00133     int out_bits;
00134 } g722_decode_state_t;
00135 
00136 #if defined(__cplusplus)
00137 extern "C"
00138 {
00139 #endif
00140 
00141 /*! Initialise an G.722 encode context.
00142     \param s The G.722 encode context.
00143     \param rate The required bit rate for the G.722 data.
00144            The valid rates are 64000, 56000 and 48000.
00145     \param options
00146     \return A pointer to the G.722 encode context, or NULL for error. */
00147 g722_encode_state_t *g722_encode_init(g722_encode_state_t *s, int rate, int options);
00148 
00149 int g722_encode_release(g722_encode_state_t *s);
00150 
00151 /*! Encode a buffer of linear PCM data to G.722
00152     \param s The G.722 context.
00153     \param g722_data The G.722 data produced.
00154     \param amp The audio sample buffer.
00155     \param len The number of samples in the buffer.
00156     \return The number of bytes of G.722 data produced. */
00157 int g722_encode(g722_encode_state_t *s, uint8_t g722_data[], const int16_t amp[], int len);
00158 
00159 /*! Initialise an G.722 decode context.
00160     \param s The G.722 decode context.
00161     \param rate The bit rate of the G.722 data.
00162            The valid rates are 64000, 56000 and 48000.
00163     \param options
00164     \return A pointer to the G.722 decode context, or NULL for error. */
00165 g722_decode_state_t *g722_decode_init(g722_decode_state_t *s, int rate, int options);
00166 
00167 int g722_decode_release(g722_decode_state_t *s);
00168 
00169 /*! Decode a buffer of G.722 data to linear PCM.
00170     \param s The G.722 context.
00171     \param amp The audio sample buffer.
00172     \param g722_data
00173     \param len
00174     \return The number of samples returned. */
00175 int g722_decode(g722_decode_state_t *s, int16_t amp[], const uint8_t g722_data[], int len);
00176 
00177 #if defined(__cplusplus)
00178 }
00179 #endif
00180 
00181 #endif

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