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comparison spandsp-0.0.6pre17/src/spandsp/private/g726.h @ 4:26cd8f1ef0b1
import spandsp-0.0.6pre17
| author | Peter Meerwald <pmeerw@cosy.sbg.ac.at> |
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| date | Fri, 25 Jun 2010 15:50:58 +0200 |
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| 3:c6c5a16ce2f2 | 4:26cd8f1ef0b1 |
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| 1 /* | |
| 2 * SpanDSP - a series of DSP components for telephony | |
| 3 * | |
| 4 * private/g726.h - ITU G.726 codec. | |
| 5 * | |
| 6 * Written by Steve Underwood <steveu@coppice.org> | |
| 7 * | |
| 8 * Copyright (C) 2006 Steve Underwood | |
| 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 Lesser General Public License version 2.1, | |
| 14 * as 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 Lesser General Public License for more details. | |
| 20 * | |
| 21 * You should have received a copy of the GNU Lesser General Public | |
| 22 * License along with this program; if not, write to the Free Software | |
| 23 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | |
| 24 * | |
| 25 * $Id: g726.h,v 1.4 2009/04/12 09:12:11 steveu Exp $ | |
| 26 */ | |
| 27 | |
| 28 #if !defined(_SPANDSP_PRIVATE_G726_H_) | |
| 29 #define _SPANDSP_PRIVATE_G726_H_ | |
| 30 | |
| 31 /*! | |
| 32 * The following is the definition of the state structure | |
| 33 * used by the G.726 encoder and decoder to preserve their internal | |
| 34 * state between successive calls. The meanings of the majority | |
| 35 * of the state structure fields are explained in detail in the | |
| 36 * ITU Recommendation G.726. The field names are essentially indentical | |
| 37 * to variable names in the bit level description of the coding algorithm | |
| 38 * included in this recommendation. | |
| 39 */ | |
| 40 struct g726_state_s | |
| 41 { | |
| 42 /*! The bit rate */ | |
| 43 int rate; | |
| 44 /*! The external coding, for tandem operation */ | |
| 45 int ext_coding; | |
| 46 /*! The number of bits per sample */ | |
| 47 int bits_per_sample; | |
| 48 /*! One of the G.726_PACKING_xxx options */ | |
| 49 int packing; | |
| 50 | |
| 51 /*! Locked or steady state step size multiplier. */ | |
| 52 int32_t yl; | |
| 53 /*! Unlocked or non-steady state step size multiplier. */ | |
| 54 int16_t yu; | |
| 55 /*! int16_t term energy estimate. */ | |
| 56 int16_t dms; | |
| 57 /*! Long term energy estimate. */ | |
| 58 int16_t dml; | |
| 59 /*! Linear weighting coefficient of 'yl' and 'yu'. */ | |
| 60 int16_t ap; | |
| 61 | |
| 62 /*! Coefficients of pole portion of prediction filter. */ | |
| 63 int16_t a[2]; | |
| 64 /*! Coefficients of zero portion of prediction filter. */ | |
| 65 int16_t b[6]; | |
| 66 /*! Signs of previous two samples of a partially reconstructed signal. */ | |
| 67 int16_t pk[2]; | |
| 68 /*! Previous 6 samples of the quantized difference signal represented in | |
| 69 an internal floating point format. */ | |
| 70 int16_t dq[6]; | |
| 71 /*! Previous 2 samples of the quantized difference signal represented in an | |
| 72 internal floating point format. */ | |
| 73 int16_t sr[2]; | |
| 74 /*! Delayed tone detect */ | |
| 75 int td; | |
| 76 | |
| 77 /*! \brief The bit stream processing context. */ | |
| 78 bitstream_state_t bs; | |
| 79 | |
| 80 /*! \brief The current encoder function. */ | |
| 81 g726_encoder_func_t enc_func; | |
| 82 /*! \brief The current decoder function. */ | |
| 83 g726_decoder_func_t dec_func; | |
| 84 }; | |
| 85 | |
| 86 #endif | |
| 87 /*- End of file ------------------------------------------------------------*/ |